1) Nutrients and Oxygen to cells

2) Waste, carbon dioxide to excretion organs

3) Transport signaling molecules

4) Transport immune cells

5) Regulate body temperature

Diffusion is very slow over long distances

Metazoans

Diffusion is slow - solution is bulk flow 

Primarily evolved to transport gasses in relation to respiration

Oxygen for ATP and waste CO2 secretion

Time necessary for molecule to diffuse between two points is proportional to the square of the distance between them

Exponentially increases ad distance gets greater

Circulatory system - functionally connects organs of exchange with cells

Convective transport

Tubes, pumps, one-way valves

Fluids move down pressure gradients (ΔP)  and are opposed by resistance (R)

Q(flow) = ΔP/ R

Ohm's Law: Movement result of a force. Movement impeded by resistance.

Contractile chambers - heart chambers or vessels

External pumps - peripheral skeletal muscle 

Peristaltic contractions - heart or vessels

[image]

Open - Elongated dorsal tube with multiple chanmbers that have calves that move hymolymph (no blood / extracellular fluid difference) that moves out of heart and into open area in body called sinus. Sinus flow is unidirectional.

Closed - high pressure connected tube unidirectional, circular system. The blood is always distinct from the interstitial fluid

Heart 

Arteries 

Arterioles

Cappilaries (start flow back to heart)

Venules 

Veins

No, Arteries do not always have oxygenated blood and viens do not always have deoxygenated blood

Arteries defined - away from heart

Viens - toward heart

By their direction of flow

Arteries away from heart

Veins into heart

Single circuit - Fishes - Only two chamers (1 atrium and ventricle) that make a single loop to first the gill then the systemic capillaries, back to heart.

Double circuit - Mammals and Bird - 4 chambered heart, pulmonary (lung) and systemic systems

Amphibians - 3 chambered heart- not complete separation of lung (pulmocutenous) and systemic circuit.

Reptiles - connection of the two circuits  

Higher gradient created for gas exchange because of oxygenated and deoxygenated blood is separated

Oxygenated blood to systemic circuit high necessary for movement and energy

Resistance is inversly proportional to the function of the radius to the fourth power

Tube gets smaller, resistance gets larger

NS modulates by contricting or dilating blood vessels

Resistors in series increases total resistance in series

- decrease flow

Resistors in parallel decrease the total resistance in series

- increase flow because increased total radius.

- Individual capillaries will have slower flow but the total circuit will have greater flow b/c of multiple in parallel.

Voume ⁄ unit time

Low in capillaries; High in heart

Distance traveled/ unit time

Determined by pressure and cross-sectional area of blood vessel

Velocity is inversly related to radial size

- Capillaries have low velocity of flow

- The capillary bed however has velocity similar to larger vessels b/c total cross-sectional area is large

Right Atrium

Right Ventricle

Pulmonary Artery

Lungs

Pulmonary Vein

Left Atrium 

Left Ventricle

Aorta

Organ System

Systemic Veins

Anterior Vena Cava

Right Atrium

* Atrioventricular valves are between Atrium and Vetricles

** Semilunar valves are between Ventricles and Arteries (Pulmonary or Aorta)

Atrioventricular valve between Atrium and Ventricles

Also called tricuspid (right) and bicuspid (left) 

Open during ventricular relaxation(diastole) and artial dilation (systole)

Between the Right venticle and the pulmonary artery & the left ventricle and aorta

Open during ventricular contraction (systole) / atrial relaxation (diastole)

The pulmonary semilunar valve prevents back flow to what area

During what stage in cardiac cycle? 

Prevents backflow into right ventricle

During ventricular diastole, artial systole

The valve is open during ventricular systole (contraction)

Uninucleated

Intercalcated disks - desmosomes and gap junctions allow for conduction of electricle signals. High tensile ability.

Vertebrate hearts are myogenic - cnotraction initiated by cardiomyocyte

Intercalcated disks 

desmosomes and gap junctions allow for electrical conduction

In the sinoatrial (SA) node (pacemaker)

Cells with fastest rhythm

Sodium permeability is higher → spontaneous depolarization

Resting potential higher ~-65 mV

Na+ funny channels open, at depolarization close and T-Ca2+ channels open, AP, T channels close K+ open

Autonomic - parasympathetic and sympathetics

or

Hormones

Thyroid hormones control beta-adrenergic receptors sensitive to norepinephrine

Epinephrine from adrenal medulla

SA node / Pacemaker

Sets rate and timing of cardiomyocyte (muscle) contraction

Electrical impulses originate here

Alone depolarize at 100 bmp

Parasympathetics turn down to 70 bpm

AV node

Delays the electrical impulse from the SA node through the internodal pathways by 0.1 sec allowing the atria to empty completely

Sends impulse through bundle of His to Purkinje fibers

Alone 40-60 bmp (w/out SA node)

Specialized cardiac muscle fibers that carry electrical impulses from the AV node to the purkinje fibers

Apex of heart 

Speciallized cardiomyocytes w/ rudamentary contractile elements that also receive electrical impulses from bundle of His

Causes contraction of Ventricles up through artia 

Higher resting potential -65mV v -85 of other cells

Funny non-seletive cation channels - influx Na+

Higher Na+ permeability

Amount of blood (mL) pumped by the R and L ventricle in each contraction

Avg. in human is 0.07 liter 

CO = SV x HR

Stroke volume (blood pumped by ventricles per contractions) x HR (bpm)

avg. for human is 5 liter/ min (all blood in your body)

depolarization of atria

Signal is at pacemaker and AV node

initial bump on graph

measures the depolarization of the large ventricle muscles

Spike in middle of graph

measure of repolarization of ventricle

last bump on the graph

Pressure is very high and very low in verticle

Remains only high in arteries (does not drop)

Pressure drops as it goes through arterioles, capillaries, venules, and lowest at veins.

[image]

Respiratory pumps - as we inhale  blood flows into blood vessels, but as we exhale compresses vessels pushing blood to heart

Skeletal muscle contractions

Backflow of blood is prevented by one-way valves

A measure of how eaily a structure can be stretched

Veins are highly compliant reservoirs for blood

Complaince = ΔVolume / ΔPressure

Can be adjusted by adjusting venomotor tone - increasing increases venous return to heart

Through baroreceptors 

Increased mean arterial pressure (MAP) increases barorecptor firing

goes to Medulla

decreases sympathetic output 

less NE release 

Baroreceptors in kidneys regulate blood volume thus pressure

Chemoreceptors

Negative feedback and opposite can occur

[image]

Located in Carotid and Aortic arteries

↓ Partal pressure of P_O2 and ↑ P_CO2 or ↓ pH cause decrease in parasympathetic activity leading to an incease in HR [image]

CO is adjusted in concern with TPR

TPR is regulated by the dilation and constriction of arterioles

Result: Blood flow = physiological demand

PRINT SLIDE 20 LECTURE 2

Depends on the metabolic need of the tissues under hormonal or NS control

1) Contraction of smooth muscle (tunica media) of the arterioles supplying capillaries

2) Pre-capillary sphincters

- rings of smooth muscle control flow between arterioles and venules (throughfare channels bypass the capillary bed) - contraction decreases flow to capillaries and increases to throughfare channels.

Continuous, Fenestrated, and Sinusoidal

[image]

Slow rate of blood flow through capillaries allows for movement

1) Simple diffusion

2) Endocytosis/Exocytosis - transcytosis

3) Paracellular pathway - hydrostatic pressure

Lymphatic capillaries = network of closed end tubules in intercellular space

Lymph capillaries→ lymph ducts → lymph nodes 

Lymph nodes filter before returning to veins

Functions

1) Transports interstitial fluid back to blood

2) Transports absorbed fat from small intestine to blood

3) Provides immunologic defences 

The larger the gradient the faster the diffusion

1) Solubility

2) Partial pressure gradient

3) Temperature 

4) Distance 

5) Surface area - large banching into alveoli in lungs

Laws you need to know: Fick's, Ideal gas, Henry's, Grahams, and combination law of F's H, and G's.

dQ/dT = D x A x (dc/dx)

Rate of Diffusion (mol/sec) = Diffusion coefficient (D) x Surface area x Concentration (pressure) gradient (dc/dx)

D=Diffusion coefficient (cm²/sec) - index of ease of diffusion of particular substance in given medium (depends on temp and solubility) 

A = Surface area membrane (cm²) 

Diffusion is greatest if x is smaller (distance)

Combines importance of temperature, solubility, surface area, distance concentration of gasses (all factors of diffusion) 

Measure of the thermodynamic activity of molecule

Dalton's Law of Partial Pressures: 

Each gas exerts its own partial pressure that adds to the total pressure of system

Sum of the partial pressures (total pressure) is proportional to the total # gas molecules

Relates presure to the # gas molecules and volume of chamber

PV = nRT

Pressure x Volume = # moles x Gas constant x Temp (Kelvin) 

Total pressure is proportional to # gas molecules at a constant temperature

Gases dissolve, diffuse, and react according to their partial pressures, and not necessarily according to their concentrations in a gas mixture.

Partial pressure depends on the temperature of the gas.

Disolve in liquid

based on partial pressure in air and solubility in liquid

Partial pressure in air and solubility in liquid

Henry's Law:

[G] = P_gas x S_gas

concentration gas in liquid = partial pressure in air x solubility in liquid

Solubility is affectd by temperature

[G] = P_gas x S_gas

Concentration gas dissolves = Partial pressure of that gad x Solubility of that gas in medium

O₂ has low solubility in water

For oxygen to get to cells it must first dissolve in liquid 

Oxygen has low solubility in water

Henry's Law states: [G]  =P_gas x S_gas

The partial pressure of O₂ is low in fishes exteral environment and the Solubility of O₂ is low

In order to get the same amount of O₂ as an air breathing animal it must pass 30x the amount of medium over gils. 

Also since as Temp increase solubility decreases, but fishes are ectotherms they look for thermoclimes

Fish are ectotherms so their metabolic demands increase with temperature 

However solubility of gasses (O₂) decrease with temperature 

Temperature

Salinity

Partial pressure / concentration in air

Solubility in medium

Graham's Law :

Diffusion of gas into liquid is proportional to its solubility, but inversly proportional to the square of its molecular weight

Smaller the gas the faster the diffusion

Difusion rate = S_gas / √MW

takes into account molecular weight and solubility of molecule in medium

Salinity and Solubility

Diffusion of gas into liquid is proportional to its solubility, but inversly proportional to the square of its molecular weight

Smaller the gas the faster the diffusion

Difusion rate = S_gas / √MW

Diffusion rate = D × A × ΔP_gas × S_gas / X × √MW

D = diffusion coefficient

A = surface area

ΔP_gas = partial pressure gradient

S_gas = solubility in medium

X = diffusion difference

MW = molecular weight

Combines Fick's, Henry's, and Graham's

O2 requires a transport system within the body since diffusion is slow

 Circulatory system

 O2 transport molecules (e.g., hemoglobin)

and

O2 binding molecules in tissues with high metabolic demand (e.g., myoglobin in muscle). 

Dessication is problem for air breathing since respiratory surfaces must be moist and H2O is lost by evaporation

Water breathing must expend more energy moving medium over respiratory organ since low O₂ concentration in water.

Bulk flow or ventilation

then diffusion

Non-directional ventilation - wave gills through external environment

Tidal ventilation - system of tubes to lungs

Unidirectional ventilation - in through mouth to internal gills

Tidal ventilation (bidirectional)- P_O2 of blood increases as P_O2 of medium decreases

Not most efficient system, but avoids desiccation  

Lungs terminate in aveoli (sites of gas exchange)

Ventilation controlled by contraction and dilation of diaphragm 

Tidal Volume

Vital capacity

Risidual volume

Surfactant

The volume of air inhales/ exhaled with each breath

~500 mL for adult

The maximum tidal volume during forced breath

~ 3.4 -4.8 L for college age

Prevents aveoli in lungs from collapsing

Some air remains in the lungs during exhalation

Lungs hold more air than vital capacity

Reduces surface tension in liquid coating alveolar surface

Increases complaince of alveoli

Detergent (a mix of phospholipids and proteins) secreted by alveolar epithelium

Corticosteroids induce production 

Residual volume

Surfactant

Makes greater exchange efficiency possible

Blood always exposed to O₂ rich medium

Countercurrent flow best

[image]

Birds have stiff, hexagonal lungs and air sacs.

Birds maximize gas exchange at the respiratory surface by a crosscurrent mechanism.

Lungs employ unidirectional and continuous flow - air sacs and lungs fill separately

A metalloprotein that bind O₂ increasing carrying capacity of blood

Oxygen binds to the heme (iron containing) on hemeglobin → oxyhemoglobin

Oxygenated state is "relaxed" (R), deoxygenated is "tense" (T)

tetramere protein - each molecule can hold 4 oxygen

pH effects the O₂ equillibrium of hemoglobin (the bohr effect) 

pH effects O₂ equillibrium of hemoglobin

[image]

Physiological acclimatization - climbing mountain

Developmental acclimatization - living in high elevation

Decrease the affinity of hemoglobin for O₂

1) Increase Temp

2) Increase CO₂

3) Decrease pH

4) Increase 2,3- diphosphoglycerate (2,3-DPG) - allosteric regulator of hemoglobin made by red blood cells

[image]

More CO₂ → lower pH

Decreased P_O2 → red blood cells produce more 2,3-diphosphoglycerate 

→ decreased hemoglobin affinity for O₂

more oxygen to cells

Only 1 heme group

High affinity for O₂ (greater O₂ saturation at pO₂ than hemoglobin)

Good molecule for O₂ storing in cells

Found in muscles, very high tissue content in diving mammals

Transported in 3 forms:

Dissolved, carbaminohemoglobin, or bicarbonate ion (reacted with water)

At tissues, conditions favor coversion to bicarbonate ion. (chloride shift)

In lungs, conditions favor release of CO2 from HCO3- (reverse chloride shift)

Haldane effect: deoxygenated blood can carry more CO2 than ozygenated

Bicarbonate - PCO2 in cells in higher than in blood.

Carbonic anhydrase in RBC catalyzes CO2 + H2O to HCO3- + H+.

 A Cl-/bricarbonate exchanger moves bicarbonate out of RBC.

"Chloride shift"

[image]

P_CO2 is ↑ in environment-bicorbonate converted to CO2 and leaves RBC

[image]

The brainstem (medulla oblongata and pons) 

Baroreceptors in carotids and aorta relay changes in [Co2] and [O2] 

Stretch receptors in lungs prevent over expansion through negative feedback

Aquatic animals primarily sense O2 while we sense CO2

Does NOT depend on increased blood [CO2]

Increased body temp

Adrenal gland secretes epinephrine

Reflexes from body movements (proprioceptors) to cerebral cortex

Cerebral cortex

Dilation / contriction of smooth muscle around bronchioles

Parasympathetics - constrict - less gas exchange - cranial nerve X

Sympathetics - dilate - more gas exchane - thoracic spinal cord

Vasoconstriction/dilation: Low O2 (hypoxia) signals vasoconstriction

Low O2 - vasoconstriction - less gas exchange 

High O2 - vasodilation - more gas exchange

PRINT SLIDE 29 lecture 4

Erethropoletin is hormone makes more RBC- more oxygen - hemocrit

[image]

Amino acid changes in hemoglobin allowing for more Oxygene - geese

Increase myoglobin concentration - seals

Water

ionic 

pH

Nitrogen balance

affect blood volume, BP, and thus heart function

Osmosis: Net movement of water down its concentration gradient

1 osmole = 1 mol solute 

1 osmolar = 1 mol solute / Liter

Most important solutes : Na+, K+, Cl- 

1) Asymmetric distribution of transporters/ channels

2) Junctions that regulate paracellular function

3) Diversity of epithelial cell types

4) High mitochondrial density to provide ATP for ATPases (ion pumps) 

Solutes move across epithelial layers by transcellular or paracellular transport

Osmoregulators 

Osmoconformers

Having osmolarity equal to that of environment

Do not control osmotic condition of body fluids

Do regulate ionic composition somewhat - so not exact same composition

Marine invertebrate

Actively control osmotic condition

Some are regulators, but almost isosmotic to environment - (Chondrichthyes; Elasmobranchii (e.g. sharks) and Holocephali)

Some have similar osmolarity as us - (Actinopterygii; Chondrostei and Neopterygii (Teleostei - bony fishes; e.g., tuna)

Different mechanisms for freshwater and saltwater fishes

Freshwater - do not drink, pee a lot, actively pump salt into body

Maintain osmotic pressure of body fluid above that of environment.

Saltwater - drink lots, pee little, continuously exrete salt.

Maintain osmotic pressure of body fluids below that of environment.

Osmotic regulation in fishes

Stenohaline - restricted to narrow range of salinities

Euryhaline - can adapt to wide range of salinities (tilapia). Preform smoltification.

Gills - chloride cells (epithelia) move ions against concentration gradients

Intestine 

Kidney

Must actively take up salt

2 types of cells:

PNA- (take up sodium, acid secreting)

PNA+ (takes up Ca2+, base Cl- secreting

Both cells use carbonic anhydrous catalyst

[image]

Actively gets rid of salt

[image]

Must prevent dessication (water loss):

1) Body coverings

2) Nocturnal behavior

3) Production of disaccharide trehalose (protects cells by replacing water associated w/ proteins and membranes) 

4) Reduce evaporation

5) Reduce urine production / make concentrated urine

Stratum corneum - dead outer layer drived from corneocytes that are derived from keratinocytes - prevent water loss

[image]

Oxidation of fats, proteins, and sugar make water

Camel 

Exrete in dilute urine (ammonia - ammonioteles , uric acid - Birds/ uricoteles, urea - mammals/ ureoteles)

Or 

Convert to less toxic form Glutimine to transport

[image]

Urea is produced in the liver, released into blood, and is excreted in the kidney

Ornithine-urea cycle - The main exretory product mammals

Glutamine (less toxic ammonia), CPSI or CPSII → carbmoyl phosphate → Urea

Uses ATP 

In mito and cyoplasm

So we can make more concentrated urine

conserve water

In the kidney where the urine drains

eventually leads to the ureter

1) Ion balance

2) Osmotic balance

3) Blood Pressure

4) pH balance

5) Excretion

6) Hormone Production (metabolism/ catabolism)

Excreted by the kidney

increases the oxygen carrying capacity in blood

Excreted by kidney

precursor to angiotensin II 

regulates salt/water balance

Excreted by kidney

Created vitamin B

Functional unit of kidney

[image]

The glomerulus

[image]

Epithelium of Bowman's capsule that is fenestrated allowing for fluids and solutes to pass into capsule (not proteins) 

Has foot process / slits for filtration

hydrostatic pressue (due to gravity) and oncotic pressure (due to proteins remaining in capillaries pulling water)

[image]

constriction/ dilation of afferent arterioles

By neural pathways: sympathetic cause constriction

Local regulation: increased BP activates stretch-sensitive ion channels on the afferent arteriole smooth muscle - depolarization contraction

[image]

Proximal tubule - large microvilli (for solute reabsorption along w/ H2O)

Decending limb - no microvilli (only H2O reabsorption)

Ascending limb - Largest microvilli (NaCl reabsorption) 

Collecting duct - No microvilli (H2O and urea reabsorption )

Secondary active transport of Na+/ glucose symport on the apical (kidney) side 

Primary active transport of Na+/K+ on basolateral (cappilary) side

Cl- goes from apical to basolateral by diffusion

Primary urine (isosmotic to blood)

[image]

Reabsorption of water

thin

Loop of henle is a coutercurrent multiplier = makes concentrated urine

NO aquaporins (impermeable to H2O)

NaCl moves into blood by seriers of secondary active transport 

[image]

K+ secreted, Na+ and water are reclaimed

Potential hormone regulation

Duct in cortex permeable to H2O only

Duct in inner medulla permeable to urea (→ hyperosmotic peritublar fluid)

→ greater H2O reabsorption and hyperosmotic urine

[image]

Affects the collecting duct

Vasopressing (ADH): G-protein → ↑ aquaporin insertion in membrane

Aldosterone: nuclear receptor → ↑ Na+ channels in distal tubule and collecting duct and thus also ↑ water reabsoption

Renin/Angiotensin: Renin makes angiotensin that leads to vasoconstriction (slows filtration increasing blood volume), increased aldosterone, dipsogenic (makes thirsty)

Atrial Natriuretic peptide (ANP): vasodilation and ↓ Renin → Na+ excretion (into urine) followed by water, ↓Blood volume, ↓ BP, ↑urine

 G-protein → ↑ aquaporin insertion in membrane

Leads to increasing the blood vollume and BP 

nuclear receptor → ↑ Na+ channels in distal tubule and collecting duct and thus also ↑ water reabsoption

Leads to increased blood volume and BP

 Renin makes angiotensin that leads to vasoconstriction (slows filtration increasing blood volume), increased aldosterone, dipsogenic (makes thirsty)

Leads to increased blood volume and BP

Vasodilation and ↓ Renin → Na+ excretion (into urine) followed by water, ↓Blood volume, ↓ BP, ↑urine

Leads to decreased blood volume and BP