BIOS 3755- Human Physiology Exam 3

how much blood does heart pump

60 mL per contraction

~54 gal per hr

components of blood

plasma, wbc, rbc, platelets

plasma: function and components

Transports carbon dioxide, digested food, urea, hormones and heat energy

pt, nutrients, inorg subst, metabolic waste, hormones

hematocrit

% of blood that is RBC; 45%

how much % is plasma in blood

55%

what is the "buffy coat" in blood

leukocytes and platelets

rbc made from

bone marrow`

rbc properties (4)

no nucleus

120 day life cycle

bilirubin made when broken down

most fe recycled back to bone marrow

low rbc means ______ which includes (4)

anemia:

fe deficiency

bone marrow failure

hemorrhage

blood cell production issue

sickle cell

abnormal hemoglobin; sickle shape causes blockage to blood flow

treatment for sickle cell (5 steps)

1. bone marrow makes diseased hemaglobin

2. stem cells extracted

3. stem cells modified (silence BCL11A gene)

4. new stem cells

5. production of healthy hemaglobin

wbc made in ___________; do they have a nucleus?

bone marrow;

have nuclei

circ sys: 3 components

fluid for nutrient/gas exchange

tubes for transport (vessels)

musc pump for movement

3 types of circulatory systems

none, simple (open), closed

how eukaryotic cells obtain O2 and expel CO2

1. ventilation

2. gas exchange

3. circulation

4. cellular respiration

open circ (3)

blood bathes organs directly (circ fluid IS interstit fluid)

may or may not exchange o2; has o2 carrying pigment but not in cells, free in hemolymph

low Pressure = less e cost

insect circ sys does NOT have

o2 exchange

closed circ sys (3)

blood is confined to vessels

transports co2 and o2

high pressure = more e cost

annelid (worm) circ sys is ... and has ....

closed circ sys; mult hearts and no lungs

single circulation

bony fishes, rays, and sharks

2 chambered heart.

blood passes 2 cap beds (gill and systemic) before returning to heart

drawbacks of simple circulatory system

after passing through gill caps, blood enters system caps slowly; fish cannot handle high bp

do some fishes have lungs?

yes (lungfish); direct return of blood to heart from lung

amphipians hearts have ...

3 chambered-hearts (2 atria, 1 ventricle)

in amphibians, the pulmonary and systemic circuits are

partially separated

in amphibians, the these fluids mix in the ventricle

oxygenated and deoxygenated blood

what does the pulmonary vein return to in amphibians?

left atrium

reptiles heart

still 3 chambers, but partially divided ventricles w septum

how does the septum in reptiles make their heart better than amphibians

improves separation of pulmonary and systemic circulation

birds/mammals heart

4 chambers. septum completely separates ventricle into 2 parts.

pulmonary and systemic circ completely separated!

advantage of bird/mammal heart

high rate of oxygen delivery to tissues/ more activity

which animals have double circulation

amphibians, reptiles, and mammals

where does oxygen-poor blood flow through to pick up O2 through the lungs?

the pulmonary circuit

amphibians have what kind of circuit?

pulmocutaneous circuit (skin)

What is the adaptive advantage of having a double circulation system and three-chambered heart of amphibians, over the single circuit and two-chambered heart of fish?

A. There can be capillary beds in both the respiratory organ and body systems.

B. The additional chamber increases the pressure of blood flow to the respiratory organ.

C. Oxygenated blood can return to the heart for additional pumping before going to systemic flow.

D. Oxygenated blood is kept completely separate from deoxygenated blood in the heart.

C. Oxygenated blood can return to the heart for additional pumping before going to systemic flow.

pulmonary circuit

flow from/to lungs

systemic circuit

flow to/from rest of the body

capillaries connect

arterioles and venules

Flow of blood in the cardiovascular system is (11 parts)

r ventricle> pulmonary artery> cap of r&l lung> pulmonary vein> l atrium> l ventricle> aorta> cap of head/forelimbs> cap of lower limbs> superior vena cava> inf. vena cava> r atrium

do veins have high or low pressure

low bp; carry blood from capillaries

why do cap. have such low bp?

to permit for gas/nutrient exchange b/t blood and interstitial fluid

Veins always carry deoxygenated blood.

True or False?

False! Veins carry blood to the heart w or w/o oxygen

mammalian hearts are 2 pumps operating in _

parallel

which side of the heart receives venous blood from systemic circulation? from lungs?

right side; ;left side

what kind of valves in human heart

1 way valves. prevent backflow

blood flow rate changes depending on circumstances. t or f

true

systole and diastole

Contraction and relaxation of the ventricles

what is the function of the "one-way" valves in the heart?

separates the atria and ventricle;

prevents backflow of blood into atria and continues in one direction

cardiac cycle steps

1. AV entrances are open/ SL valves are closed (atrial and ventricular diastole)

2. atrial systole; ventricular diastole

3. AV are closed/ SL valves are open. (atrial diastole, ventricular systole)

There are no valves at the point where venous blood flows into the atria.

T or F

true

atrioventricular and semilunar valves

separates atria from ventricle

separates ventricles from arteries

coronary skeleton function

supports one-way valves and helps w conduction of action potentials

what initiates depolarization in heart? also called pacemaker of heart

SA node

Electrical pathway of the heart

SA node, AV node, Bundle of His, Purkinje fibers

the sa node depolarization propogates from

bundle of His along Purkinje fibers in ventricles

skeletal vs cardia musc graph

cardiac: has plateau after AP!

repolarization is much slower due to fibers propagating. prevents tetany

how does the heart avoid tetany (musc. spasms)?

repolarization happens much more slowly

AP in heart diff from other cells (SA node pacemaker potential)

depolarization from Ca2+ influx rather than Na+, efflux K+. though Na+ does enter before Ca2+, it is Ca2+ causes dep

Na+ channels open at ~60mV

K+ diminishes as MP rises

SA node depolarize to threshold

during _ in heart, dep cannot occur

absolute refractory period

in heart, plateau phase is longest for fibers that contract _

ventricles

this is bc prolonged contractions in ventricles are more fatal than those in atria

Why is there a plateau of membrane potential despite Ca and K entering and exiting?

...

what can a change in ECG pattern mean? (3)

cardiac rhythmic disturbances

inadequate coronary artery blood flow

electrolyte disturbances

EKG 3 parts

P wave, QRS complex, T wave

what sets rate and timing for cardiac musc contraction

pacemaker cells in SA node. initiate dep

intercalated discs def and f(x)

specialized connections between myocardial cells containing gap junctions and desmosomes

branching network. allows pulse to spread quickly

does the AV node start contraction immediately after SA node?

no, slightly delayed so that the ventricles can fill up

electrical activation of heart pathway: (5 steps)

1. signal starts at SA,

2. spread to both atria, atria contract,

3. signal delay at AV

4.signal spread down fibers to apex then reach ventricles, ventricles contract

5. ventricles relax

atrial excitation (beginning and ending)

begins: SA node

end: AV node

ventricular excitation (beginning and ending)

begins: atrial relaxation

ends: ventricle contracting

vagus nerve vs accelerator nerve

para, symp

baroreceptors

arterioles constrict, veins constrict, cardiac output constrict

cardiac acceleration (4 steps)

sympathetic ns

epi/norepi -> B1 receptor -> Na and Ca influx increased, dep -> increased HR

cardiac deceleration (5 steps); what system is it apart of

parasymp ns

ACh -> muscarinic receptors -> K efflux increased and Ca influx decreased -> increased time to depolarize -> HR decreased

Frank-Starling Law

The greater the stretch, the stronger is the heart's contraction. This increased contractility results in an increased volume of blood ejected (Increased SV)

more stretch -> more force

fetal heart: 2 bypasses due to no lungs

foramen ovale: allows deoxy blood to flow directly from left to right atrium

ductus arteriosis: connects pulmonary artery to aorta

physical differnce bt arteries and veins

thicker elastic layer in arteries

Do veins or arteries have valves?

veins

thinner walls

low pressure/resistance

are veins or arteries thicker

arteries

also more elastic

high pressure

blood velocity in diff vessels

artery > vein > capillary

total area diff in vessels

cap > vein > artery

BP in diff vessels

artery > cap > vein

role of musc in regulating BP

SMOOTH musc

contract/relax

local vasocontraction

same volume of blood in smaller cross sectional area will increase speed and bp

local vasodilation

same volume of blood in larger cross sectional area will decrease speed and bp

what brings back blood in veins to heart?

skeletal musc and valves!

neg pressure applied by heart

circulating blood pushing in the back

what system controls blood flow to specific tissues? what are they called and where are they located? how do they work?

autonomic ns

smooth muscles calles precapillary sphincters. in arterioles

These muscles can constrict or relax, either completely cutting off circulation or flooding specific tissues with blood.

Can respond immediately to physiological demands placed on the body

what happens when BP drops?: kidneys

kidneys release renin -> renin circulation activates angiotension -> vessels constrict

what happens when BP drops?: hypothalamus

stretch sensors decrease firing -> hypothalamus release vasopressin -> vessels constrict ->

what causes BP to keep falling

decreased blood to tissues -> wastes accumulate -> vessels widen

Poiseuille's Law

-calculates rate of flow through a pipe of confined space (laminar flow)

Q= (πr^4 ∆P)/8ηL

η: viscosity of the fluid

Q: flow rate (volume flowing per time)

ΔP: pressure gradient

r: radius of tube

L: length of tube

Thus resistance is inversely proportional to the fourth power of the radius (i.e., reduction of vessel diameter by a factor of 2 causes a 16-fold increase in resistance!)

3 types of capillaries

Continuous

Fenestrated

Sinusoidal

continuous cap: permeability, location

lowest permeability

found in muscle, brain, lungs, connective tissues, exocrine glands

fenestrated cap: permeability, location

intermediate permeability, found in kidneys, intestines, endocrine glands

has pores

sinusoidal cap: permeability, location

very permeable, found in liver, bone marrow, spleen, lymph nodes, adrenal cortex

paracellular gap

what determines permeability of capillary beds?

junctions bt endothelial cells

what makes capillaries leaky

hydraulic pressure

forces fluid out arteriole end

Large molecules remain, increasing osmotic concentration of blood; coupled with dropping blood pressure in the capillary as it progresses towards the venule results in a net inward flow of fluid.But, volume out is slightly greater than volume in!

at arterial end of capillary, BP and osmotic P

BP > osmotic P

fluid flows out cap into interstit. fluid

at venule end of cap: BP and osmotic P

BP < osmotic P

fluid flow from interstit. fluid to cap

direction of osmotic pressure in capillaries

increases from arteriole to venule

what happens to excess lymph

The fluid (lymph) which accumulates in the interstitial spaces is collected into small ducts (lymphatic vessels). These drain into larger lymphatic ducts which merge into large thoracic duct that is connected to vena cava adjacent to heart (returning lymph to general circulation)

lymph carries _ to _

pathogens to nodes

where they are destroyed or stimulate production of antibodies to fight infection