cardiovascular physiology

Question 1

why can unicellular or very small organisms manage without a circulatory system?

Answer 1

they can just diffuse molecules, since their membranes are so thin.

Question 2

what are the three components of a circulatory system?

Answer 2

a pump (heart)
system of tubes (vessels)
fluid to circulate (blood)

Question 3

what do vessels do?

Answer 3

they keep fluids separate from tissues

Question 4

what do sinuses do?

Answer 4

they allow the fluid to make direct contact with the tissues

Question 5

what is a closed circulatory system?

Answer 5

fluid will always remain in the vessels and is separate from interstitial fluid. supports higher flow rates and control of where fluid goes.

Question 6

what is an open circulatory system?

Answer 6

fluid/hemolymph enters a sinus at least once, then bathes the tissues. circulating fluid mixes with interstitial fluid

Question 7

what does the heart do for the circulatory organization and flow

Answer 7

the heart creates the pressure that drives blood flow. it also has sensory endocrine functions

Question 8

what does the arterial system do?

Answer 8

distributes blood, and helps regulate blood pressure

Question 9

what do the capillaries do?

Answer 9

the site of gas/nutrient exchange

Question 10

what does the venous system do?

Answer 10

returns blood to the heart, and acts as a blood volume reservoir

Question 11

what is a hematocrit?

Answer 11

the proportion of blood made of red blood cells

Question 12

what are the components of blood?

Answer 12

plasma
white blood cells
red blood cells

Question 13

what is plasma made of?

Answer 13

water, electrolytes, proteins, nutrients, hormones, waste products

Question 14

how can you divide the components of blood up?

Answer 14

centrifugation

Question 15

what is the shape of a red blood cell, and what is another word for it?

Answer 15

erythrocytes
disc shaped, biconcave

Question 16

what is a stack of RBCs called

Answer 16

rouleaux

Question 17

what happens to RBCs during differentiation?

Answer 17

they lose all organelles. they have no mitochondria or ribosomes or nucleus

Question 18

what is erythropoiesis and EPO

Answer 18

stimulated directly by peptide hormone erythropoietin (EPO), indirectly by thyroxine, androgens and growth hormone.

EPO is a glycoprotein from the kidneys/liver. released in peripheral tissues if there is low oxygen.

EPO stimulates increased cell division rate in erythroblasts and in the myeloid stem cells, and speeds up RBC maturation.

Question 19

name all heart valves

Answer 19

aortic valve
pulmonary valve
AV valve (tricuspid)

Question 20

describe all vertebrate blood vessels (artery and vein categories)

Answer 20

large veins and regular veins are the same. then there are venules, no tunica media/intima. thin walled and most distension

elastic arteries have a thicker tunica media (muscle) layer than the veins. muscular arteries have an even thicker layer. then arterioles are just super thin tunica media. very little pressure drop when compared to blood leaving heart.

capillaries are very tiny, just endothelium. no smooth muscle or connective tissue.

Question 21

fundamental law of circulation

Answer 21

blood flow = ΔP/R

difference in pressure between 2 points. generated by heart contractions / resistance that impedes flow

resistance is calculated, determined by internal blood viscosity and external interaction with vessel wall.

Question 22

which cardiovascular circuit has the most pressure and why?

Answer 22

systemic has more pressure than the pulmonary, because the systemic blood needs to get to the whole body. the lungs and heart are close together so less pressure is needed to get blood there.

Question 23

what happens to pressure and velocity as blood moves through the system?

Answer 23

pressure decreases as blood moves through the system
velocity is highest in arteries, lowest in capillaries, due to less resistance in increased cross sectional area. velocity is mid in the veins. (fast ,drops, picks up. think of it like a train delivering sm. speeds to destination, slows for delivery… then speeds up a little as it goes home)

Question 24

describe the pulmonary circuit’s heart morphology

Answer 24

gets blood from the right ventricle, which is much thinner walled (less muscle)

prevents fluid filtration in lungs, prevents damage of delicate alveoli, minimizes right ventricle workload

Question 25

describe systemic circuit heart morphology

Answer 25

gets blood from left ventricle. very thick strong muscle layer.
ensure good fluid filtration in systemic capillaries
maintain high flow rates to many tissues, left ventricle has high workload

Question 26

describe the mammalian cardiac cycle

Answer 26

the cardiac cycle describes what happens between one beat, and the beginning of the next.

atria contract (systole) forces blood into relaxed ventricles. then atrial diastole starts and ventricle systole begins. this contraction pushes AV valves closed, but isn’t enough pressure to open semilunar valves…. as pressure builds with more ventricular systole (pressure exceeds arteries), the semilunar valves open and blood is ejected. then ventricles diastole, blood flows back against semilunar cusps which closes them. blood fills atria as ventricles passively fill.

Question 27

what is systole and diastole?

Answer 27

systole is contraction
diastole is relaxation