This is a collective term that refers to all of the chemical reactions that occur throughout the body.

metabolism

What are the 2 phases of metabolism?

1. catabolism

2. anabolism

the breakdown of a polymer into its monomers or even smaller components

Examples:

• the breakdown of a protein into amino acids

• the breakdown of a glucose molecule into CO2 and H2O 

catabolism

1. Catabolism starts via the process of ________ in the lumen of the GI tract and is completed inside of the cells of the body.

2. Catabolic processes release ________ (_______); then this* is then used to power anabolic reactions.

1. digestion

2. energy (ATP and heat)

the synthesis of a polymer from several monomers

Examples:

• the synthesis of a triglyceride from 3 fatty acids and 1 glycerol molecule

• the synthesis of a protein from amino acids

anabolism

- Anabolic reactions occur within cells. 

1. _______ reactions require energy, which is released as ATP is hydrolyzed.

2. As mentioned earlier, this ATP is supplied by _______ reactions.

3. Cells require _______ reactions to grow, to repair themselves, and to produce secretory substances such as hormones, neurotransmitters, mucus, etc.

1. Anabolic

2. catabolic

3. anabolic

If sufficient O2 is present (aerobic conditions), most cells catabolize glucose for energy via a process known as ______________.

cellular respiration

What is the formula for the cellular respiration of glucose?

glucose + O2 → CO2 + H2O + 30-32 ATP

Cellular respiration of glucose involves 4 sets of reactions, what are they?

1. glycolysis

2. formation of Acetyl Coenzyme A

3. Krebs cycle

4. electron transport train

What are 2 main ways to produce ATP via cellular respiration of glucose?

1. substrate-level phosphorylation

2. oxidative phosphorylation

the process by which a phosphate group is transferred from a phosphorylation intermediate → to ADP → to form ATP

substrate-level phosphorylation

the process by which ATP is formed using NADH+H+, FADH2, an H+ ion gradient, and the electron transport chain

oxidative phosphorylation

If O2 is absent or in low concentration in the cell (anaerobic conditions), glucose can still be catabolized, but only a small amount of energy is produced. What is the formula of this reaction?

glucose → lactic acid + 2 ATP

Most cells also contain enzymes that catabolize fatty acids for energy via cellular respiration. Give the proper formula for this reaction.

fatty acid + O2 → CO2 + H2O + ATP (variable amount)

Fatty acids enter into cellular respiration by being converted into ______________.

acetyl coenzyme A

Hepatocytes (liver cells) contain enzymes that can catabolize amino acids for energy via cellular respiration. Give the proper formula for this reaction.

amino acid + O2 → CO2 + H2O + ATP (variable amount)

Breaking down amino acid.

1. The amino acid is ________, which means that the amino group (NH2) is removed.

2. The amino group is converted to ________.

3. The rest of the amino acid is then converted into a ________, which is an intermediate organic compound.

#3 is then converted into pyruvic acid, acetyl CoA, or an intermediate of the Krebs Cycle and then subsequently broken down into CO2, H2O, and ATP

1. deaminated

2. ammonia (NH3)

3. keto acid

Amino acids converted to ammonia.

1. Most of the ammonia molecules produced from the deamination of amino acids are subsequently converted into _____. However, some of the ammonia molecules may not undergo this conversion reaction, and therefore, remain as ammonia.

2. This* and any unconverted ammonia are then released from the _____ into the blood.

3. The ______ filters the blood of the *** and ammonia and excretes these substances from the body via urine.

1. urea

2. liver

3. kidney

True or False: The types of metabolic reactions that occur in your body depend on how long it has been since you have eaten a meal.

True.

Metabolic reactions are organized into 2 functional states. What are they?

1. absorptive state

2. postabsorptive state

the period when ingested nutrients are entering the blood from the GI tract to provide energy for the body

absorptive state

the period when the GI tract lacks nutrients and energy is supplied by the breakdown of the body’s own nutrient reserves

postabsorptive state

What are the 2 major events occur during the absorptive state?

1. Some of the absorbed nutrients are utilized for the body’s energy needs.

2. Any absorbed nutrients in excess of the body’s energy needs are converted into nutrient reserves.

During the absorptive state, most cells of the body produce ATP by catabolizing ________ via cellular respiration.

glucose

During the absorptive state, what is the body’s main energy source?

glucose

Amino acids.

1. Some of the absorbed amino acids are used to _______ proteins like actin and myosin in skeletal muscle and albumins in the liver.

2. Other absorbed amino acids are catabolized for energy by _______.

1. synthesize

2. hepatocytes

Lipids.

1. During the ______________, most of the absorbed lipids (short chain fatty acids, long chain fatty acids, and monoglycerides) are not catabolized for energy.

2. Instead, they are sent to ____________ and stored as triglycerides (fat).

1. absorptive state

2. adipose tissue

- glucose polymer

- Excess glucose is stored as this* in the liver and skeletal muscle

glycogen

the synthesis of glycogen

Glycogenesis

- consists of adipocytes that store triglycerides

- As mentioned earlier, most of the absorbed lipids are sent directly to this* and then stored as triglycerides.

- In addition, excess amino acids and excess glucose can be converted to triglycerides in the liver and then shipped to adipose tissue for storage.

adipose tissues

True or False: If a particular type of food is fat-free, it means that you can eat it in excess because it won't be converted to fat.

False.

 - Just because a particular type of food is fat-free does not mean that you can eat it in excess because it can still be converted to fat.

the synthesis of triglycerides

Lipogenesis

1. During the ______________, the GI tract is empty of nutrients, but the cells of the body still need energy.

2. Thus, the body’s own nutrient reserves are ________ to obtain this energy.

1. postabsorptive state

2. catabolized

What is the major goal of the postabsorptive state?

To maintain a normal blood glucose concentration (70 to 110 mg/dL of blood)

1. Keeping the blood glucose concentration _______ is vital to the survival of the brain.

2. This is because of the fact that neurons can only ________ glucose (and not fatty acids, amino acids, etc.) for energy during a ______ postabsorptive state.

1. constant

2. catabolize; normal

- If the blood glucose concentration falls below normal, brain function is compromised and a coma occurs.

What are the 2 major events occur during the postabsorptive state?

1. The blood glucose concentration is maintained at a normal level due to the catabolism of the body’s nutrient reserves.

2. Most tissues undergo glucose sparing

- the catabolism of glycogen into glucose

- takes place in the liver and skeletal muscle

- Once this* occurs in the liver, the glucose is released into the blood.

- In skeletal muscle, the glucose that is formed from this* is often catabolized for energy.

glycogenolysis

Glycogenolysis.

1. If the skeletal muscle exists under anaerobic conditions, then the glucose is converted into _________, which is released into the blood.

2. The liver then takes up the ***, converts it back to _______, and then releases this* into the blood.

1. lactic acid

2. glucose

- the catabolism of triglycerides into glycerol and fatty acids

- takes place in adipose tissue

Lipolysis

Lipolysis.

1. After lipolysis occurs, the glycerol and fatty acids are released into the ______.

2. The _____ then takes up the glycerol, converts it to glucose, and then releases the glucose into the blood.

1. blood

2. liver

- the breakdown of protein into amino acids

- takes place in skeletal muscle

protein catabolism

Protein catabolism.

1. After protein catabolism occurs, the ________ are released into the blood.

2. The liver then takes up each ***, converts it to ______, and then releases this* into the blood.

1. amino acids

2. glucose

In a normal postabsorptive state, ________ is the main nutrient reserve catabolized, while only small amounts of lipid and an even smaller amount protein are broken down.

glycogen

- the formation of new glucose from a noncarbohydrate source

- Examples: the formation of glucose from lactic acid, glycerol, or an amino acid

Gluconeogenesis

Most tissues undergo glucose sparing.

1. This means that most cells of the body switch to ________ catabolism as their main source of energy; this leaves more glucose in the blood for the brain.

2. The *** used by the body cells originate from _______ in adipose tissue.

3. Cells take up the ________ from the blood and then catabolize them for energy.

1. fatty acid

2. lipolysis

3. fatty acids

Most tissues undergo glucose sparing.

3. In addition, hepatocytes take up some of the fatty acids from the blood and convert them to highly acidic compounds called ______ and then releases them into the blood. (Examples of these include acetone, acetoacetate, and β-hydroxybutyrate.)

4. Cells then take up the *** and then ________ them for energy.

3. ketones (also called ketone bodies)

4. catabolize

1. Note that in a normal postabsorptive state, only a very small (trace) amount of ______ are present in the blood.

2. However, if the postabsorptive state becomes extended (such as during a prolonged fast or starvation, lipolysis increases, which causes *** production to ______.

1. ketones

2. increase

the postabsorptive state lasts for a few days

prolonged fasting

the postabsorptive state last for weeks

starvation

During prolonged fasting or starvation, several events occur:

1. Glycogen reserves have become ________.

2. Lipolysis and ketone production ________.

3. ________ catabolism increases.

4. Brain metabolism changes, allowing neurons to catabolize _______ in addition to glucose for energy.

1. depleted

2. increase

3. Protein

4. ketones

What are the 4 hormones that regulate metabolism?

1. insulin

2. glucagon

3. cortisol

4. thyroid hormones

Insulin is secreted from the ______ cells of the _______ in response to a high blood glucose concentration.

- beta (β)

- pancreas

What is the major hormone of the absorptive state?

insulin

What does insulin cause?

glucose uptake by cells

Insulin causes glucose uptake by cells:

1. This _______ the blood glucose concentration back down to normal, physiological levels.

2. Insulin achieves this goal by increasing the number of ____________ in the membranes of most cells.

3. Note that _____ cells and ______ do not require insulin to take up glucose.

1. reduces

2. glucose transporters (GLUTs)

3. liver; neurons

Insulin causes glucose uptake by cells:

1. Insulin causes __________ in the liver and muscle.

2. Insulin causes __________ uptake and ______ synthesis in skeletal muscle.

3. Insulin causes fatty acid & glycerol uptake and ________. 

1. glycogenesis

2. amino acid; protein

3. lipogenesis

The ______ cells of the pancreas secrete _______ in response to a low blood glucose concentration.

- alpha (α)

- glucagon

What is the major hormone of the postabsorptive state?

glucagon

1. The __________ released from adipose tissue are used by the body’s cells for energy.

2. The glycerol released is converted into glucose in the liver via the process of __________.

1. fatty acids

2. gluconeogenesis

________ is secreted by the __________ in response to a stressful situation (physical or emotional trauma, infection, surgery, starvation, extreme hot or cold temperatures, fear, severe exercise, etc.).

- Cortisol

- adrenal gland

Cortisol is another hormone that promotes the reactions of the ______________ when the body is experiencing a stressful situation.

postabsorptive state

Cortisol generates _______ that the body can use to handle a stressful situation.

energy (ATP)

Cortisol generates energy (ATP) that the body can use to handle a stressful situation.

- Cortisol achieves this goal in the following ways: 

1. Cortisol acts on ____________ to cause protein catabolism and then releases ___________ into the blood.

1. skeletal muscle; amino acids

Cortisol generates energy (ATP) that the body can use to handle a stressful situation.

- Cortisol achieves this goal in the following ways: 

2. Cortisol acts on ____________ to cause lipolysis and then release of __________ and _______ into the blood.

2. adipose tissue; fatty acids; glycerol

Cortisol generates energy (ATP) that the body can use to handle a stressful situation.

- Cortisol achieves this goal in the following ways: 

3. Cortisol acts on the _____ and _________ to cause glycogenolysis and then releases _______ into the blood.

3. liver; skeletal muscle; glucose

Cortisol generates energy (ATP) that the body can use to handle a stressful situation.

- Cortisol achieves this goal in the following ways: 

4. Cortisol acts on the _____ to cause gluconeogenesis and then releases _______ into the blood.

4. liver; glucose

1. Once the glucose, fatty acids, and amino acids are released into the blood, the cells of the body can then take up these nutrients and then break them down via ______________  to produce enough energy to handle the stressful situation.

2. Since cortisol increases the blood glucose levels, it is also called a __________.

1. cellular respiration

2. glucocorticoid

Cortisol reduces inflammation and other immune responses.

- occurs in response to any tissue damage caused by injury or any foreign microbes that invade the body

- characterized by redness, pain, heat, and swelling

- serves as a “call to arms” that attracts leukocytes (white blood cells) to the area to fight the invading pathogens.

- Whenever a tissue is damaged, nearby mast cells (cells found in connective tissue) and basophils (a type of white blood cells) cause inflammation by releasing a substance called _________.

histamine

1. Cortisol reduces inflammation by reducing the amount of _______ released from mast cells and basophils in the injured tissue.

2. In addition, cortisol reduces the ability of ______________ to mount an immune response to pathogens in the inflamed area.

3. These anti-inflammatory and anti-immune responses of cortisol are probably designed to allow the person to handle the ______________ without having to be sidetracked by pain and other symptoms that are associated with inflammation and immune reactions.

4. Since cortisol inhibits immunity, it is often administered as an ____________ drug to a person who receives an organ transplant.

1. histamine

2. white blood cells

3. stressful situation

4. immunosuppressive

- includes triiodothyronine (T3) and thyroxine (T4)

- secreted by the thyroid gland

thyroid hormone

Which is more potent, T3 or T4?

- T3 is more potent than T4

- Once these thyroid hormones are released into the blood, most of the T4 is converted into T3.

What regulates the secretion of T3 and T4 hormones?

hypothalamus

Whenever the blood concentration of T3 and T4 is low, the hypothalamus secretes __________________, which causes the anterior pituitary to secrete _____________; this* then acts on the thyroid gland to promote secretion of T3 and T4.

- thyrotropin releasing hormone (TRH)

- thyroid stimulating hormone (TSH)

Thyroid hormone functions.

1. Thyroid hormones are vital to the maturation of the __________ during fetal development and childhood.

2. Thyroid hormones achieve this goal by stimulating ________.

3. Thyroid hormones _______ the basal metabolic rate (BMR).

1. nervous system

2. osteoblasts

3. increase

1. The ____________ is the amount of energy produced (i.e. released) in an individual who is awake, resting, and recumbent (lying down) as that person’s cells catabolize food via cellular respiration over a given period of time.

2. Some of the energy produced is in the form of ATP, while the rest is in the form of _____.

1. basal metabolic rate (BMR)

2. heat

Recall the equation for cellular respiration:

monomer (glucose/fatty acid/amino acid) + O2 → CO2 + H2O + energy (ATP, heat)

- Hence, an increase in the BMR as caused by thyroid hormones also increases the body temperature.

1. Thyroid hormones increase the BMR by activating genes that cause the production of _________________ involved in cellular (aerobic) respiration.

2. The thyroid hormone secretion _______ when a person is in a cold climate; this helps the person to adapt and to stay _______ due to more body heat from the increased BMR.

1. various metabolic enzymes

2. increases; warmer

A ______ is a measure of how much energy is released when a particular type of food is catabolized via cellular respiration.

calorie

Most of the Calories in our food are derived from the catabolism of ___________, _______, and ____.

- carbohydrates

- proteins

- fats

1. The catabolism of 1g of carbohydrate yields about __ Cal of energy.

2. The catabolism of 1g of protein also yields about __ Cal of energy.

3. The catabolism of 1g of fat yields about __ Cal of energy.

1. 4

2. 4

3. 9

Calculate the number of Calories from carbohydrate in this slice of pizza:

27 g carbohydrate

14 g fat

12 g protein

27 g carbohydrate x 4 Cal (1 g carb) = 108 Cal

Calculate the number of Calories from fat in this slice of pizza:

27 g carbohydrate

14 g fat

12 g protein

14 g fat x 9 Cal (1 g fat) = 126 Cal

Calculate the number of Calories from protein in this slice of pizza:

27 g carbohydrate

14 g fat

12 g protein

12 g protein x 4 Cal (1 g protein) = 48 Cal

What is the total number of calories in this slice of pizza?

27 g carbohydrate

14 g fat

12 g protein

108 Cal + 126 Cal + 48 Cal = 282 Cal

1. How do you calculate the BMR for men?

2. Women?

1. Body weight in kg (lbs. / 2.2) x 1 Cal x 24 hours = Male BMR

2. Body weight in kg (lbs. / 2.2) x .9 Cal x 24 hours = Female BMR

The ________________ equals your BMR plus the amount of calories burned from activities that involve muscular work.

total metabolic rate (TMR)

1. If your daily caloric intake equals your total metabolic rate, then your weight __________.

2. If your daily caloric intake is greater than your total metabolic rate, then your weight __________.

3. If your daily caloric intake is less than your total metabolic rate, then your weight __________.

1. remains the same

2. increases

3. decreases

How many calories does 1 pound equal?

3500 calories

1. Lipids are ________ and do not dissolve well in blood.

2. Recall that blood is ________ due to the presence of water.

3. Thus, proteins typically must increase the solubility of lipids in blood by coating them, forming structures called ________.

1. hydrophobic

2. hydrophilic

3. lipoproteins

consists of a lipid core surrounded by a protein coat

lipoprotein

Lipoproteins are classified based on their densities; there are 4 major types of lipoproteins, what are they from lightest to heaviest?

1. chylomicrons

2. VLDLs (very low-density lipoproteins)

3. LDLs (low-density lipoproteins)

4. HDLs (high-density lipoproteins)

- formed within absorptive cells of the small intestine

- consist of an outer protein coat and an inner core of triglycerides (formed from long chain fatty acids and monoglycerides that have recombined) and cholesterol molecules

chylomicrons

Function of chylomicrons.

1. Chylomicrons carry ______________ from the small intestine to adipose tissue for storage.

2. After entering the _______ circulation, chylomicrons drop off their triglycerides in adipose tissue.

3. As the triglycerides leave the chylomicrons, the chylomicrons become smaller and smaller, turning into chylomicron remnants that consist of the remaining ________ and ________.

4. The chylomicron remnants are eventually taken up by the _____ and disassembled. During the disassembly process, the cholesterol molecules are released and become incorporated along with other lipids into __________ lipoproteins.

1. dietary (ingested) triglycerides

2. systemic

3. cholesterol; protein

4. liver; very low-density

- formed in the liver

- consist of an outer protein coat and an inner core of the following lipids: triglycerides that were synthesized in the liver, cholesterol molecules that were synthesized in the liver, and dietary cholesterol from chylomicron remnants that were disassembled in the liver.

very low-density lipoproteins (VLDLs)

Function of VLDLs.

1. VLDLs transport ________ made in the liver to adipose tissue for storage.

2. After depositing these* in adipose tissue, the VLDLs shrink and the proportions of cholesterol and protein increase. As a result, the VLDLs turn into ________ lipoproteins.

1. triglycerides 

2. low-density

- formed as VLDLs release their triglycerides into adipose tissue

- consist of an outer protein coat and an inner core of cholesterol molecules

low-density lipoproteins (LDLs)

Function of LDLs.

1. LDLs transport ________ to body cells.

2. The cells of the body use the cholesterol to help synthesize ______________.

⇒Recall that the plasma membrane of a cell is a lipid bilayer that consists of phospholipids, cholesterol, and proteins.

3. In addition, certain cells use cholesterol to synthesize ____________.

1. cholesterol

2. plasma membranes

3. steroid hormones

Function of LDLs.

1. Cells of the __________ use cholesterol to synthesize cortisol, aldosterone, and the adrenal androgens.

2. Cells of the ______ use cholesterol to synthesize estrogen and progesterone.

3. Cells of the ______ use cholesterol to synthesize testosterone.

- called “bad cholesterol” because as LDLs travel to body cells, if too much cholesterol is present inside of them, then the excess cholesterol will ooze out of the LDLs and form lipid plaques in the walls of blood vessels (arteriosclerosis)

1. adrenal gland

2. ovaries

3. testes

- formed in the liver

- initially resemble a deflated beach ball, consisting of a protein coat with an with an empty interior

- gradually add more and more cholesterol to their interiors by removing cholesterol that has been deposited on arterial walls or from body cells.

high-density lipoproteins (HDLs)

Function of HDLs.

1. HDLs absorb unused cholesterol from the circulation and bring it to the _____.

2. This* then excretes the cholesterol into _____, which eventually becomes part of the feces; hence, *** is the major mechanism by which cholesterol is excreted from the body.

- called “good cholesterol”

1. liver

2. bile

Diet.

1. There are several types of foods that are high in cholesterol and, therefore, should be eaten in moderation. What are they?

2. Cholesterol intake should be under ____ mg/day

1. eggs, dairy products, beef, pork, shellfish (shrimp, etc.).

2. 300 mg/day

The cholesterol produced by the liver is used to make what 3 things?

1. bile salts

2. steroid hormones

3. plasma membranes

1. The total blood cholesterol should be under ____ mg/dL of blood.

2. The ideal LDL concentration: < ____ mg/dL of blood

3. The ideal HDL concentration: > ____ mg/dL of blood

1. 200 mg/dL of blood (deciliter)

2. < 130 mg/dL of blood

3. > 40 mg/dL of blood

- most common endocrine disorder

- caused by an inability to produce or use insulin

- 4th leading cause of death in USA

diabetes mellitus

- when the concentration of ketone bodies in the blood rises above normal -- the ketone bodies, most of which are acids, must be buffered

- if too many accumulate, they decrease the concentration of buffers, such as bicarbonate ions, and blood pH falls

- abnormally low blood pH: ketoacidosis

ketosis

a genetic error of protein metabolism characterized by elevated blood levels of the amino acid phenylalanine

phenylketonuria

eating in response to emotional drives, such as feeling stressed, bored, or tired

emotional eating

- body weight is more than 20% above a desirable standard due to an excessive accumulation of adipose tissue

- more than 1/3 of the adult population in the US is this*

obesity

a disorder in which protein intake is deficient despite normal or nearly normal caloric intake, characterized by edema of the abdomen, enlarged liver, decreased blood pressure, low pulse rate, lower-than-normal body temperature, and sometimes mental retardation

kwashiorkor

an imbalance of total caloric intake or intake of specific nutrients, which can be either inadequate or excessive

malnutrition

- a type of protein-calorie undernutrition that results from inadequate intake of both protein and calories

- characteristics include retarded growth, low weight, muscle wasting, emaciation, dry skin, and thin, dry, dull hair

marasmus

- disorders that affect all major body systems and are among the most common endocrine disorders

- Ex: Congenital hypothyroidism, myxedema, Graves disease, goiter

thyroid gland disorders

- hypersecretion of cortisol by the adrenal cortex

- causes include a tumor of the adrenal gland that secretes cortisol, or a tumor elsewhere that secretes ACTH

Cushing’s syndrome

- adrenal glands don't produce enough hormones

- hyposecretion of glucocorticoids and aldosterone causes this*

- majority of cases are autoimmune disorders in which antibodies cause adrenal cortex destruction or block binding of ACTH to its receptors

Addison’s disease