Term
| What are the endocrine glands? What other organs/tissues contain endocrine cells? |
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Definition
Pituitary, Thyroid, Parathyroid, Adrenal, and Pineal
Hypothalamus, Thymus, Pancreas, Ovaries/testes, Kidneys, Liver, Stomach, Heart, Skin, and adipose tissue |
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Term
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Definition
| secretes product into interstitial fluid and diffuse into the blood |
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Term
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Definition
| Secretes products into ducts or lumens or to the outer surface of the body |
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Term
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Definition
Mediator molecules released in one part of the body that regulate activity in other parts of the body. There are two types: local hormones and circulating hormones.
They are used to help regulate: extracellular fluid, metabolism, biological clock, contraction of cardiac & smooth muscle, glandular secretion, some immune functions, growth & development, and reproduction. |
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Term
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Definition
Act locally on neighboring cells (paracrine) or on the same cell that secreted them (autocrine) without first entering the blood stream.
Examples of these: IL-2 released from helper T cells stimulates proliferation of helper T cells and activation of cytotoxic T cells. (autocrine)
Histamine released by mast cells stimulates HCl secretion from parietal cells in stomach (paracrine) |
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Term
| Circulating Hormones (2 types) |
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Definition
Enter interstitial fluid and then the bloodstream
Lipid soluble: bound to transport proteins
Water soluble are free to come and go |
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Term
| Steroid hormones (lipid-soluble hormone) |
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Definition
| ________ are derived from cholesterol. Have chemical groups attached to core of structure making each structure unique. Examples: cortisol, testosterone, estrogens, progesterone, and aldosterone |
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Term
| Thyroid hormones (lipid-soluble hormone) |
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Definition
| Have tyrosine rings with attached iodines. Very lipid soluble |
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Term
| Nitric Oxide (lipid-soluble hormone) |
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Definition
| A hormone which also acts as a neurotransmitter |
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Term
| Peptide and protein hormones (water-soluble hormone) |
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Definition
| These are chains of amino acids. They are hypothalamic releasing and inhibiting hormones. Some examples: ADH, oxytocin, hGH, TSH, ACTH,insulin, glucagon, EPO |
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Term
| Biogenic Amines (water-soluble hormone) |
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Definition
| These are modified amino acids. Some examples include: catecholamines: NE, epinephrine, dopamine, serotonin, melatonin, and histamine |
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Term
| Eicosanoids (water-soluble hormone) |
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Definition
| These are derived from arachidonic acid (20 carbon fatty acid) These are local hormones. Some examples: prostaglandins and leukotrienes. |
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Term
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Definition
| Hormones only affect target cells with specific membrane or intracellular (protein) receptors. Water-soluble hormones can be stored in vesicles. Lipid-soluble cannot. |
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Term
| General mechanism of action for hormones (how does it work)? |
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Definition
1) bind to cell surface or receptor inside target cell
2) cell responds via: synthesis of new molecules, change in membrane permeability, and altered rates of reaction.
Note: that different target cells may respond to the same hormone differently.
Example: Hepatocytes - insulin stimulates glycogen synthesis
Adipocytes-insulin stimulates triglyceride synthesis |
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Term
| More specific steroid hormone action/mechanism |
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Definition
1) lipid-soluble hormone diffuses into cell
2) Activated receptor-hormone complex alters gene expression
3)Newly formed mRNA directs snythesis of specific proteins on ribosomes
Note: receptors typocally intracellular, and these hormones work by changing the level of specific gene expression. |
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Term
| More specific peptide hormone action/mechanism |
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Definition
1) binding of hormone (first messenger) to its receptor activates G protein, which activates adenylate cyclase
2) activated adenylate cyclase converts ATP to cAMP
3)cAMP serves as a second messenger to activate protein kinases
4)Activated protein kinases phosphorylate cellular proteins
5)Millions of phosphorylated proteins causes reactions that produce physiological responses
6)Phosphodiesterase inactivates cAMP
note: Peptide hormones bind to cell surface receptors. These peptide hormones evoke changes in the activity of existing proteins through a second messenger, and these second messengers alter the phosphorylation state of existing proteins. |
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Term
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Definition
| Water soluble (peptide) hormones, bind to cell surface receptors which causes the production of intracellular second messengers. Hormones (which are also known as first messengers) may increase or decrease the level of second messengers. Same hormone may use different second messengers in different target cells (such as norepinephrine). Second messengers also initiate a cascade of biochemical reactions, often involving phosphorylation or dephyosphorylation, within the target cell. Some examples of second messenger: caMP, calcium ions, cGMP. |
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Term
| What does the hypothalamus receive input from? |
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Definition
| The hypothalamus receives input from the cortex, thalamus, limbic system and internal organs. |
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Term
| What does the hypothalamus do? |
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Definition
| The ________ provides a link between the external and internal environment and the endocrine system. It also controls the anterior pituitary gland with different releasing and inhibiting hormones. The ________ releases other hormones directly through the posterior pituitary |
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Term
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Definition
| Two sets of capillaries connected by veins. |
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Term
| releasing mechanism of hormones from hypothalamus to anterior pituitary. |
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Definition
1)Hypothalamic neurosecretory cells secrete hormones into vesicles.
2) A signal tells hormones to be released
3) vesicles travel through neuron (primary plexus of hypophyseal portal system)
4)At the secondary capillary bed hormones have and effect on the anterior pituitary. |
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Term
| Five main cell types of anterior pituitary. |
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Definition
| somatotrophs,thyrotrophs, lactotrophs, gonadotrophs, and corticotrophs |
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Term
| Somatotrophs (anterior pituitary cell) |
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Definition
| secrete human growth hormone |
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Term
| Thyrotrophs(anterior pituitary cell) |
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Definition
| secrete thyroid stimulating hormone |
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Term
| Lactotrophs(anterior pituitary cell) |
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Definition
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Term
| Gonadotrophs(anterior pituitary cell) |
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Definition
| secrete follicle stimulating hormone and lutenizing hormone |
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Term
| Corticotrophs(anterior pituitary cell) |
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Definition
| secrete adrenocorticotropic hormone and melanocyte stimulating hormone |
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Term
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Definition
| Produced by somatotrophs in the anterior pituitary. The target cells are liver, skeletal muscle, cartilage, and bone. Within target cells, human growth hormone stimulates the increase synthesis of insulin-like growth factors that act locally or enter bloodstream. |
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Term
| Insulin-like growth factors (Human growth hormone) |
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Definition
| _______increase cell growth and cell division by increasing the uptake of amino acids and synthesis of proteins. They stimulate lipolysis in adipose tissue so fatty acids are used for ATP. And they decrease use of glucose for ATP production by most body cells so blood glucose levels remain high enough to supply brain. |
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Term
| Regulation of hGH release (human growth hormone) |
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Definition
hGH released in bursts every few hours. The release of hGH is regulated by GHRH and GHIH.
What stimulates GHRH?
-hypoglycemia, deep sleep, decreased fatty acids and increased amino acids in the blood, increased sympathetic stimulation.
Stimulation for GHIH?
-Hyperglycemia, REM sleep, increased fatty acids and decreased amino acids in the blood, obesity, low levels of thyroid hormones, high levels of hGH |
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Term
| Follicle Stimulating Hormone (FSH) |
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Definition
Gonadotropin releasing hormone (GnRH) is released from hypothalamus stimulating gonadotrophs in anterior pituitary to produce FSH.
In females FSH stimulates secretion of estrogen and initiates the formation of follicles within the ovary.
In males FSH stimulates sperm production in testes |
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Term
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Definition
GnRH is secreted by the hypothalamus and stimulates gonadotrophs in anterior pituitary to produce LH.
In females LH stimulates secretion of estrogen and progesterone. It is also involved in ovulation and formation of corpus luteum.
In males, LH stimulates the secretion of testosterone |
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Term
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Definition
| The hypothalamus regulates lactotroph cells by secreting PRH and PIH (dopamine). Lactotrophs in anterior pituitary produce prolactin. Under the right conditions, prolactin causes milk production. Suckling reduces levels of hypothalamic inhibition and prolactin levels rise along with milk production. |
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Term
| Melanocyte-Stimulating Hormone (MSH) |
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Definition
| MSH is secreted by corticotrophs in the anterior pituitary. Excessive levels of CRH from the hypothalamus increases MSH release from the anterior pituitary. PIH (dopamine) inhibits MSH release. The function of MSH is unclear in humans but high levels increase skin pigmentation. Maybe role in regulation |
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Term
| Adrenocorticotropic Hormone (ACTH) |
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Definition
Corticotropin releasing hormone (CRH) is released from the hypothalamus and stimulates corticotrophs in the anterior pituitary to release ACTH.
ACTH stimulates release of glucocorticoids (mainly cortisol) from the adrenal cortex. ACTH release is also stimulated by hypoglycemia, physical trauma, and IL-1. |
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Term
| Thyroid Stimulating Hormone (TSH) |
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Definition
| Hypothalamus regulates thyrotrophs in anterior pituitary to produce TSH (thyrotropin. TSH stimulates the synthesis and secretion of T3 and T4 (which are thyroid hormones). The purpose of these hormones is upregulate metabolism. |
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Term
| Posterior Pituitary Gland (Neurohypophysis) |
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Definition
The posterior pituitary gland does not synthesize hormones. It consists of axon terminals from two groups of hypothalamic neurons. These neurons release two peptide hormones that enter capillaries (Antidiuretic hormone (ADH) also known as vasopressin and oxytocin (OT)
The posterior pituitary resembles neural tissue with glial cells, nerve fibers, nerve endings and neurosecretory vesicles. ADH and oxytocin are made in the hypothalamus and are transported into the neurosecretory vesicles where they are stored until a signal comes to stimulate release. |
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Term
| Antidiuretic Hormone (ADH) |
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Definition
ADH produced by cells in supraoptic nucleus in the hypothalamus in response to signals from osmoreceptors (which sense the change of osmolarity in blood).
The actions of ADH include: prevent diuresis which is decrease urine production by stimulating the kidneys to return more water back to the blood . It prevents water loss in sweat glands and causes constriction of arterioles (vasopressin)
Regulation of ADH
1)Dehydration or high osmolarity of blood causes ADH to be released from posterior pituitary
2)Overhydration or low osmolarity of blood causes ADH release to be inhibited
3)ADH release is also inhibited by alcohol
4)A lack of ADH results in diabetes insipidus (inability of the kidney's to conserve H2O and excessive urination occurs, upto 20L a day). |
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Term
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Definition
Produced by cells in the paraventricular nucleus of the hypothalamus. It targets two tissues: uterus (during labor) and mammary glands after delivery.
Oxytocin Regulation during labor:
1) stimulation of uterus by baby's head causing stretch of cervix
2) Oxytocin release from posterior pituitary
3)Uterine smooth muscle contracts
4)As the baby's head is pushed into the cervix, oxytocin release increases
5)Muscle contraction, which pushes the baby further and elicits even more oxytocin release
6)when baby is born, the positive feedback loop ceases
Oxytocin Regulation after delivery:
1)Oxytocin has an effect on mammary glands by suckling and hearing baby's cry stimulates oxytocin release.
2)Oxytocin causes muscle contraction and milk ejection
3)Lactation is the process of milk production and ejection. Milk production is stimulated by prolactin and prolactin and oxytocin work together in lactation. |
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Term
| Formation of Thyroid Hormones |
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Definition
1)Iodide trapping by follicular cells
2)synthesis of thyroglobulin (TGB)
3)Release of TGB into colloid
4)Iodination of tyrosine in colloid
5)formation of T3 and T4 by combining T1 and T2 together
6)Uptake and digestion of TGB by follicle cells
7)Secretion of T3 and T4 into blood; binds to thyroid binding globulin
note: T3 and T4 are lipid soluble were as thyroglobulin is not lipid soluble. Also T4 is the precursor to T3 |
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Term
| What do thyroid hormones do? |
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Definition
| 1)Increase basal metabolic rate by stimulating the cellular use of oxygen to produce ATP which increases cellular catabolism of glucose (glycolysis), fatty acids (beta oxidation) and triglycerides (lipolysis). They also play a role in increasing synthesis of NA/K ATPase which results in more ATP is used to pump ions. ATP use produces heat which raises body temperature. This is called the calorigenic effect. They also enhance some actions of the sympathetic nervous system by up-regulating beta-receptors which increases heart rate, contractility and blood pressure. They also stimulate growth (in conjunction with hGH and insulin) particularly during development |
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Term
| Hyposecretion (thyroid disorder) |
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Definition
During development, infancy and/or early childhood resulting dwarfism and severe mental retardation (congenital hypothroidism or cretinism).
In the adult, hyposecretion results in edema, low heart rate, muscle weakness, sensitivity to cold, low body temperature, weight gain and mental dullness (myxedema). |
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Term
| Hypersecretion (thyroid disorder) |
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Definition
Hyperthroidism (Grave's Disease)
-this can result in weight loss, nervousness, tremor, increased heart rate and blood pressure, exophthalmos (edema behind eyes), high body temperature, and sweating
Goiter
-Enlarged thyroid (dietary lack of iodine) can be associated with hyperthyroidism, hypothyroidism or euthyroidism. Dietary lack of iodine leads to low thyroid hormone (T3/T4) production which stimulates TSH by negative feedback leading to stimulating thyroid gland growth. |
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Term
| What secretes calcitonin? |
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Definition
| secreted by parafollicular cells of the thyroid gland. Lowers blood Ca levels by inhibiting osteoclasts. |
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Term
| What secretes parathyroid hormone? |
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Definition
| Secreted by chief cells of the parathyroid gland. Raises blood Ca levels by stimulating osteoclasts. |
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Term
| Functions of Parathroid Hormone |
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Definition
| Raises blood calcium levels, increases activity of osteoclasts, increases reabsorption of Ca by kidney. Inhibits reabsorption of phosphate and promotes formation of calcitriol (active vitamin D3) by kidney which increases absorption of Ca and Mg by intestinal tract. |
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Term
| mineralocorticoids (zona glomerulosa) The main mineralocorticoid is aldosterone |
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Definition
| Functions of ______ include: increasing absorption (GI) and re- absorption (kidney) of Na with Cl, bicarbonate and water following it. It also promotes excretion of K and H (secretion in kidney). |
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Term
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Definition
| Hypersecretion from adrenal tumor produces _________. This is a condition where high blood pressure caused by retention of Na resulting in increased plasma volume |
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Term
| Glucocorticoids (zona fasciculata) major human glucorticoid is cortisol |
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Definition
| Key function is regulation of metabolism during stress. IT accomplishes this by increasing the rate of protein catabolism and lipolysis, promoting gluconeogenesis, and providing resistance to stress by making nutrients available. Also raises blood pressure by vasoconstriction, has anti-inflammatory and immunosuppressive action. It accomplishes this by reducing release of histamine from mast cells, decreases capillary permeability, depresses phagocytosis, and inhibits white blood cells. |
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Term
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Definition
| Caused by high levels of cortisol which is done by hypersecretion of glucocorticoids. Causes redistribution of fat to face, spindly arms and legs due to muscle loss, poor wound healing, and bruises easily. |
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Term
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Definition
| Caused by low levels of Adosterone and Cortisol. Hyposecretion of glucocortiocids and aldosterone. Causes hypoglycemia, muscle weakness, low blood pressure, dehydration due to decreased Na in blood, mimics skin darkening effects of MSH, and could causes potential cardiac arrest. |
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Term
| Androgens (zona reticularis) |
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Definition
| Small amount of weak androgens (male hormones) produced like dehydroepiandrosterone (DHEA) which is primarily used by females. It has an insignificant affect on males and may contribute to the sex drive of females. It is converted to a form of estrogen in postmenopausal women. |
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Term
| Adrenal Medulla (what are Chromaffin cells?) |
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Definition
| ________receive direct innervation from sympathetic nervous system. They develop from same tissue as postganglionic sympathetic neurons and act as a modified sympathetic ganglion. They produce 80% epinephrine (adrenaline) and 20% norepinephrine (noradrenaline). These hormones are sympathomimetic which effects mimic those of sympathetic NS and causes fight-flight behavior. |
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Term
| Alpha cells secrete what? (pancreas) |
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Definition
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Term
| Beta cells secrete what? (pancreas) |
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Definition
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Term
| Delta cells secrete what? (pancreas) |
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Definition
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Term
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Definition
________ marked by hyperglycemia which causes polyuria (excessive urine production), polydipsia (excessive thirst), and polyphagia (excessive eating).
Type I: deficiency of insulin (typically juvenile onset)
Type II: insulin insensitivity which means there is no response from cells (typically adult onset), |
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Term
| Mouth (GI tract function) |
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Definition
| Mechanical and chemical breakdown, deglutition (swallowing) |
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Term
| Pharynx and esophagus (GI tract function) |
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Definition
| Swallowing and avoiding airway |
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Term
| Stomach(GI tract function) |
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Definition
| Mechanical and chemical breakdown with some absorption |
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Term
| Small Intestine(GI tract function) |
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Definition
| Chemical and mechanical breakdown with major absorption |
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Term
| Large Intestine (GI tract function) |
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Definition
| absorption of electrolytes and some vitamins |
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Term
| Rectum and anus (GI tract function) |
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Definition
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Term
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Definition
Epithelium -stratified squamous in mouth, esophagus and anus and then simple columnar in the rest of the GI tract. The simple columnar secretes enzymes and absorbs nutrients, has specialized cells (goblet) secrete mucous onto cell surfaces, and enteroendocrine cells secrete hormones controlling organ function.
Lamina Propria - This is a thin layer of loose connective tissue which contains blood vessels and lymphatic tissue
Muscularis Mucosae - a thin layer of smooth muscle which causes folds to form in mucosal layer. It also drives local movements to increase absorption by exposing ingested material to absorptive surfaces |
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Term
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Definition
Made up of loose connective tissue that contains blood vessels, glands and lymphatic tissues.
Submucosal plexus (Meissner's plexus) - part of the enteric nervous system. It receives input from sympathetic (thoracic and lumbar spinal cord) and parasympathetic neurons (vagus nerve and sacral spinal cord). It also regulates blood vessel diameter, secretion from glands and neurosecretory neurons, and local motility caused by muscularis mucosae. |
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Term
| Muscularis Externa (GI tract) |
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Definition
Made up of skeletal muscle in mouth, pharynx, upper esophagus and anus under voluntary control. Skeletal muscle has control over deglutition and defecation. There is also a layer of smooth muscle which is under involuntary control. The smooth muscle is made up of inner circular fibers and outer longitudinal fibers which allows motility for mixing and propulsion.
Myenteric Plexus (auerbach's plexus) - part of the enteric nervous system with some functions shared with submucosal plexus. It provides parasympathetic and sympathetic innervation of circular and longitudinal smooth muscle layers. |
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Term
| Serosa or Adventitia (GI tract) |
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Definition
Serosa - for stomach and intestine. It has a serous membrane also called the visceral peritoneum. It secretes serous fluid and consists of areolar connective tissue covered with simple squamous epithelium.
Adventitia for esophagus - consists of areolar connective tissue without the epithelium |
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Term
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Definition
the visceral peritoneum covers organs
the parietal peritoneum lines the walls of body cavity
peritoneal cavity - potential space containing serous fluid |
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Term
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Definition
Mechanical Digestion (mastication or chewing) - breaks food into pieces, and mixes with saliva so that it forms a moist bolus
Chemical Digestion:
-Salivary amylase begins starch digestion in the mouth (pH 6.5-7.0), but when the bolus hits the acidic gastric juices (pH 2.5) digestion stops.
-Lingual lipase is secreted by glands in tongue and begins breakdown of triglycerides (lipids) into fatty acids and glycerols. |
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Term
| list the salivary glands in the human mouth. |
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Definition
| Major glands: Parotid, submandibular, and sublingual glands. All have ducts taht empty into the oral cavity. Sight, smell, sounds, memory of food, and tongue stimulation increase salivation. Fear and anxiety decrease salivation which leads to dry mouth. |
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Term
| What is saliva made of and what are its functions? |
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Definition
| Saliva is made up of Water, HCO3-, and enzymes. It moistens food so that you can swallow, dissolves food so that you can taste it. HCO3- buffers acidic foods and protects mouth from infection with rinsing action. It also contains lysozyme which helps destroy bacteria |
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Term
| What are the phases of swallowing? |
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Definition
1)Voluntary phase which involves the oral cavity to oropharynx. Deglutition (swallowing) starts with a voluntary phase. The food bolus is pushed by the tongue into the oropharynx.
2)Involuntary phase - which involves the pharyngeal stage (pharynx to esophagus).Begins when sensory nerves in the pharynx signal the deglutition center in brainstem. Breathing stops, soft palate and uvula rise closing off nasopharynx, vocal cords adduct, larynx rises, and epiglottis covers the larynx.The esophageal stage (esophagus to stomach)happens when the upper esophageal sphincter relaxes. Peristalsis pushes food down. Circular fibers contract behind bolus and longitudinal fibers contract in front of bolus to shorten the distance of travel. The travel time for solid foods is 4 to 8 seconds. For liquids its 1 second. The lower esophageal sphincter relaxes as good approaches. |
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Term
| Gastro-esophageal reflux disease (GERD) |
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Definition
This happens when the lower esophageal sphincter fails to open. This causes distension of esophagus making it feel like you are having major chest pains or a heart attack.
If the lower esophageal sphincter fails to close, stomach acids enter esophagus and causes heartburn (GERD). This condition is worsened by a weak sphincter and is particularly bad when laying down after a large meal. Smoking and alcohol make the sphincter relax worsening the situation. |
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Term
| Where is smooth muscle found? |
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Definition
| Smooth muscle modulates luminal pressure and tension. It is present in sheets, bundles or sheaths around tissues. It is found in the cardiovascular system, respiratory system, digestive system, urinary system, and reproductive system. |
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Term
| Smooth muscle is primarily under control of what? |
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Definition
| The autonomic nervous system "involuntary". Diffuse branching of nerve fibers, transmitters include ACh and NE. |
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Term
| what is the membrane potential of smooth muscle? |
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Definition
| The membrane potential is -50 to -60mv |
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Term
| Smooth muscle cells are categories by what? |
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Definition
based on excitation:
a)single/unitary (visceral) which include hallow organs that may store something
b)Multi-unit which is found around large arteries |
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Term
| Unitary Smooth Muscle cells (unitary means works as a unit) |
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Definition
Found in the walls of the digestive tract, gall bladder, and urinary bladder.
May not have direct contact with any motor neuron.
Cell membranes adhere to one another making transmission happen through force. |
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Term
| Autorhythmic (Unitary smooth muscle cells) |
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Definition
| Adjacent cells connect via gap junctions which transmit action potentials from one fiber to another. |
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Term
| Structure of smooth muscle |
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Definition
| Sarcoplasmic reticulum is poorly developed relative to skeletal muscle. Thick filaments of SM have actin-gripping heads along the entire length. Thick and think filaments are arranged diagonally within the cell contraction results in twisting motion. |
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Term
| Some special features of smooth muscle |
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Definition
-Capable of sustained contraction without fatigue and at very little energy cost.
-Maintains a low level of tension or tone even in the absence of action potentials
-It also has what is called the stress-relaxation response which is stretch causes initial increase in tension and tension decreases within 1-2 minutes this allows SM to change length but maintain ability to contract. |
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Term
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Definition
Generally _______length-tension relationship in smooth muscle compared to skeletal muscle.
Smooth muscle operate over a wider range of resting lengths |
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Term
| What do surface mucous cells secrete? (stomach) |
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Definition
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Term
| Mucous neck cell secrete? (stomach) |
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Definition
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Term
| Parietal cell secrete? (stomach) |
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Definition
| Hydrochloric acid and intrinsic factor |
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Term
| Chief cells secrete? (stomach) |
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Definition
| pepsinogen and gastric lipase |
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Term
| G cells secrete? (stomach) |
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Definition
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Term
| Mechanical Digestion (stomach) |
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Definition
| Gentle mixing waves occur in the stomach to mix the bolus of food with gastric juice (enzymes, acid, water) and turn it into chyme (a thin liquid). More vigorous waves traveling from the body of stomach to the pyloric region move the chyme along. Intense waves near the pylorus lead to opening of the pyloric sphincter -squirting 1-2 teaspoons into the duodenum with each wave. |
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Term
| Chemical Digestion (stomach) |
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Definition
| Protein digestion begins in the stomach. HCl denatures protein molecules and also activates pepsinogen into pepsin which is an enzyme that breaks peptide bonds between certain amino acids. Fat digestion continues with gastric lipase which splits the triglycerides in milk fat, although this is more effective at pH 5-6. HCl also kills microbes in food, and mucous cells secrete mucus to protect the stomach walls from being digested |
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Term
| What is absorbed in the stomach? |
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Definition
| Water, electrolytes, some drugs (aspirin) & alcohol. Fat content in the stomach slows the passage of alcohol to the intestine, where absorption is more rapid |
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Term
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Definition
| Also known as anticipation. Prepare the mouth and stomach for food. Cerebral cortex-sight, smell, taste and thoughts of food stimulate the parasympathetic nervous system to stimulate: salivation and gastric glands to secrete gastric juice (Vagus). |
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Term
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Definition
Also known as the breakdown of material.
Neural influences over stomach activity
-stretch receptors and chemoreceptors (pH) signal bolus entry. Vigorous peristalsis and gastric gland secretion. Chyme periodically released into the duodenum.
endocrine influences over stomach activity:
-distention and presence of food in stomach causes G cells to secrete gastrin into the bloodstream; gastrin increases gastric gland secretions and motility, and causes pyloric sphincter relaxation. |
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Term
| Neural and hormonal regulation of gastric emptying |
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Definition
| Gastric emptying increased as bolus of food enters the stomach. Distention of the stomach and presence of undigested contents increase the secretion of gastrin hormone and vagal nerve impulses. This stimulates contraction of the lower esophageal sphincter and the stomach, as well as relaxation of the pyloric sphincter for emptying |
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Term
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Definition
also known as controlled release of chyme. Entry of chyme into duodenum slows gastric activity and increases intestinal activity.
Neural influences: distension of the duodenum and chemical contents of the chyme activate sympathetic nerves, which slow gastric activity (enterogastric reflex)
Endocrine influences: distension of duodenum and contents of chyme trigger hormonal release from enteroendocrine cells in the duodenum.
secretin hormone decreases stomach secretions
Cholecystokinin (CCK) decreases stomach emptying |
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Term
| Secretin does what? (stomach) |
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Definition
| hormone decreases stomach secretions |
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Term
| Cholecystokinin (CCK) does what? (stomach) |
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Definition
| decreases stomach emptying |
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Term
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Definition
| regulates the amount of chyme released into the duodenum. Initiated by distension of duodenum and contents of the chyme. Sensory impulses sent to the medulla inhibit parasympathetic stimulation of the stomach. They also cause cholecystokinin and secretin release from the duodenum and stimulate sympathetic impulses, both of which inhibit gastric emptying. |
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Term
| What are the 3 sections of the small intestine? |
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Definition
| duodenum, jejunum, ileum. It ends at the ileocecal valve |
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Term
| What do microvilli do? (small intestine) |
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Definition
| absorb nutrients. Increase the surface area for absorption. Brush border enzymes found on the surfaces of microvilli participate in chemical breakdown of carbohydrates and proteins. Cell division within the intestinal glands produces new cells that move up. |
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Term
| What do goblet cells do? (small intestine) |
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Definition
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Term
| What do enteroendocrine cells do? (small intestine) |
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Definition
| secretes the hormones secretin, cholcystokinin, or GIP) |
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Term
| What do paneth cells do? (small intestine) |
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Definition
| secretes lysozyme and is capable of phagocytosis |
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Term
| Digestion of Carbohydrates |
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Definition
Mouth-Salivary Amylase
Stomach-doesn't happen except for mechanical breakdown
duodenum-pancreatic amylase
Brush border enzymes (maltase, sucrase, and lactase) act on disaccharides (maltose, sucrose, and lactose). They produce monosaccharides (fructose, glucose, and galactose). Lactose intolerance happens when there is no lactase and fermenting sugar results in gas and diarrhea |
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Term
| How are monosaccharides absorbed in the small intestine? |
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Definition
Absorption into epithelial cells. Glucose and galactose is transported through a sodium symporter (secondary active transport). Fructose in transported through facilitated diffusion.
Movement out of epthelial cell into bloodstream happens by facilitated diffusion. |
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Term
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Definition
| Digestion of proteins does not happen in the mouth. In the stomach HCl denatures or unfolds proteins and pepsin turns proteins into peptides (smaller AA chains). In the small intestine proteins are broken down by pancreatic enzymes which splits peptide bonds between different amino acids. Also brush border enzymes suhc as aminopeptidase (split amino acids at amino end of molecules) and dipeptidase break down dipeptides. |
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Term
| Absorption of Amino Acids and Dipeptides |
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Definition
| Absorption of amino acids and dipeptides through epithelial cells of duodenum and jejunum by active transport with Na and H ions (symporters). Movement out of epithelial cell into blood through the process of diffusion |
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Term
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Definition
| In the mouth lipids are digested by lingual lipase. In the stomach lipids are broken up by gastric lipase (important in infants). In the small intestine, emulsification by bile from liver to form micelles. Pancreatic lipase splits triglycerides into fatty acids and monoglyceride. There re no lipase enzymes in the brush border. |
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Term
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Definition
| Small fatty acids enter absorptive cells and then blood by simple diffusion. Larger lipids are sequestered within micelles after emulsification by bile; lipids enter cells by simple diffusion leaving bile salts behind in gut. Bile salts reabsorbed into blood and reformed into bile in the liver. Fat soluble vitamins (A,K,D,E) are able to enter cells with the lipid. Inside epithelial cells fats are rebuilt and coated with protein to form chylomicrons. Chylomicrons leave intestinal cells by exocytosis into a lacteal. Travel in lymphatic system to reach subclavian veins. Removed from the blood by the liver and fat tissue. |
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Term
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Definition
| Inside epithelial cells fats are rebuilt and coated with protein to form chylomicrons. Chylomicrons leave intestinal cells by exocytosis into a lacteal. Travel in lymphatic system to reach subclavian veins. Removed from the blood by the liver and fat tissue. |
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Term
| Absorption of Electrolytes |
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Definition
Sources of electrolytes include GI secretions, ingested foods and liquids.
Electrolytes are absorbed by entering epithelial cells by diffusion and secondary active transport. Sodium and Potassium move by active transport. Chloride, iodide, and nitrate follow passively. Iron, magnesium and phosphate ions use active transport. Intestinal Ca absorption requires vitamin D and parathyroid hormone |
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Term
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Definition
Absorption of fat-soluble vitamins happens by fat soluble vitamins traveling in micelles and are absorbed by simple diffusion with lipids.
Water soluble vitamins are absorbed by diffusion. Vitamin B12 must combine with intrinsic factor from the stomach parietal cells before it is transported into the cells of the ileum. Absorbed by receptor mediated endocytosis. |
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Term
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Definition
| There is about 9L of fluid that enters the GI trach per day. Small intestine absorbs about 8L. The Large intestine absorbs 90% of the last liter. Absorption is by osmosis through cell walls into vascular capillaries inside villi. |
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Term
| Pathway of Bile secretion |
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Definition
1) Bile Canaliculi
2) Hepatic ducts
3)common hepatic duct
4)cystic duct from gallbladder and common hepatic duct join to form common bile duct
5)common bile duct and pancreatic duct empty into duodenum |
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Term
| Regulation of Bile Secretion |
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Definition
1)parasympathetic impulses along vagus (x) nerve stimulate bile production by liver
2)fatty acids and amino acids in chyme entering the duodenum stimulate secretion of CCK into blood. Acidic chyme entering duodenum stimulates secretion of secretin into blood.
3)CCK causes contraction of gallbladder
4)Secretin enhances flow of bile rich in HCO3 from liver. |
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Term
| What functions does the liver have in carbohydrate metabolism |
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Definition
1)Turn amino acids into glucose - gluconeogenesis
2)Turn triglycerides into glucose -gluconeogenesis
3)Turn excess glucose into glycogen and store in the liver - glycogenesis
4)Turn glycogen back into glucose as needed - glycogenolysis |
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Term
| Liver functions in lipid metabolism |
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Definition
| The liver snythesize cholesterol and also synthesize lipoproteins, such as HDL and LDL, which are used to transport fatty acids and cholesterol in the bloodstream. It also stores some fat and breaks down some fatty acids. |
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Term
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Definition
| removes NH2 (amine group) from amino acids so can use what is left as energy source . The liver also converts resulting toxic ammonia into urea for excretion by the kidney |
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Term
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Definition
| converts one amino acid into another. The liver also synthesizes plasma proteins utilized in the clotting mechanism and immune system. |
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Term
| What are some other functions of the liver? |
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Definition
1)detoxifies the blood by removing or altering drugs and hormones (thyroid and estrogen)
2)Removes bilirubin - a waste product of red blood cell breakdown
3)releases bile salts to help digestion by emulsification of lipids
4)stores fat soluble vitamins, including A,D,E,K
5)stores iron, copper and vitamin B12
6)phagocytosis of worn out blood cells and bacteria
7)activates vitamin D - part of the vitamin activation pathway. |
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Term
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Definition
| Inflammation of the liver that can be caused by a variety of viruses, drugs, or alcohol. This can lead to cirrhosis (scarring of the liver) |
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Term
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Definition
| Scarred liver caused by chronic inflammation due to hepatitis, chemicals, parasites or alcohol |
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Term
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Definition
1.5 quarts/day at pH of 7.1 to 8.2
Contains water, enzymes and sodium bicarbonate. Also contains digestive enzymes, pancreatic amylase, pancreatic lipase, and proteases such as:
trypsinogen-activated by enterokinase(a brush border enzyme)
chymotrypsinogen - activated by trypsin
procarboxypeptidase- activated by trypsin
proelastase - activated by trypsin
trypsin inhibitor - combines with trypsin produced inside pancreas and deoxyribonuclease and ribonuclease are used to digest nucleic acids |
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Term
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Definition
| acidity in intestine causes increased sodium bicarbonate release |
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Term
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Definition
| fats and proteins cause increased digestive enzyme release |
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Term
| Functions of the Large Intestine |
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Definition
| smooth muscle can be found in the large intestine and is used for mechanical digestion. Peristaltic waves (3 to 12 contractions/minute). The large intestine also uses what is called Haustral churning which is when relaxed pouches are filled from below by muscular contractions; when they are full, they contract and move contents to next pouch. Bacteria also found in the large intestine ferment undigested carbohydrates into carbon dioxide and methane gas, and undigested proteins into simpler substances. |
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Term
| Gastroilial reflex (large intestine) |
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Definition
| when stomach is full, gastrin hormone relaxes ileocecal sphincter so small intestine will empty into large intestine. |
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Term
| Gastrocolic reflex (large intestine) |
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Definition
| when stomach fills, a strong peristaltic wave moves contents of transverse colon into rectum |
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Term
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Definition
| Gastrolcolic reflex moves feces into rectum. Stretch receptors signal sacral spinal cord. Parasympathetic nerves contract muscles of rectum and relax internal anal sphincter. External anal sphincter is voluntarily controlled |
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Term
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Definition
| happens when chyme passes too quickly through intestine. Not enough water is absorbed |
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Term
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Definition
| can be caused by decreased intestinal motility. Too much water is absorbed. Remedies are fiber, exercise and water. |
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Term
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Definition
Insoluble fiber: woody parts of plants (wheat bran, vegetable skins). Speeds up transit time and reduces colon cancer.
Soluble fiber: gel-like consistency such as beans, oats, citrus white parts, apples. In-soluble fibers lower blood cholesterol by preventing reabsorption of bile salts so liver has to use cholesterol to make more bile. |
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Term
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Definition
| Catabolic reactions break down complex organic compounds, providing energy |
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Term
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Definition
| Anabolic reactions synthesize complex molecules from small molecules, requiring energy. Exchange of energy requires use of ATP (adenosine triphosphate) molecules |
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Term
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Definition
| break down of glucose. Glucose to pyruvate/lactate |
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Term
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Definition
| Break down of glycogen. Glycogen to Glucose |
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Term
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Definition
| formation of glycogen. Glucose to glycogen |
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Term
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Definition
| formation of new glucose. Other substrates to glucose |
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Term
| Transport of Lipids by Lipoproteins (what are lipoproteins?) |
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Definition
Most lipids are nonpolar and must be combined with protein to be transported in blood
• Lipoproteins are spheres
containing hundreds of
molecules
• Lipoproteins are categorized by
function & density
• 4 major classes of lipoproteins
– chylomicrons, very low-density,
low-density & high-density
lipoproteins |
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Term
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Definition
| triglycerides are broken down into glycerol and fatty acids within liver or adipose cells in the presence of epinephrine, norepinephrine, cortisol |
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Term
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Definition
triglycerides are synthesized from amino
acids or glucose within liver or adipose cells in the
presence of insulin |
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Term
| Metabolism during absorptive state. |
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Definition
Represents the time after a meal when nutrients enter the blood and need to be stored. Hepatic portal system for glucose and amino acids - go to liver first. Lacteals for dietary fats
Storage of excess fuels occurs in hepatocytes,
adipocytes, skeletal muscle
• Most glucose entering liver cells is converted to
glycogen (10%) or triglycerides (40%)
• Dietary lipids are stored in adipose tissue
• Amino acids are deaminated to enter Krebs cycle
or are converted to glucose or fatty acids
• Amino acids not taken up by hepatocytes are used by other cells for synthesis of proteins |
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Term
| Metabolism during postabsorptive state |
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Definition
4 hours after a meal when absorption of all nutrients is complete (similar to starvation)
– Maintaining normal blood glucose level (70 to 110mg/dl of blood) is major challenge goal is to put
glucose back into the blood or use alternative fuel sources
Glucose enters blood from the liver
– glycogenolysis
– gluconeogenesis
• glycerol from adipose tissue
• amino acids and lactic acid from muscle
• Alternative fuel sources are
– fatty acids from adipose fed into Krebs as Acetyl CoA for most cells*
– oxidation of ketone bodies by heart & kidney
*Most body tissues switch to utilizing fatty acids, except brain still prefers glucose. |
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