Cardiovascular

Question 1

how does Ca increase in cardiovascular system

Answer 1

• SR less developed than in skeletal
• T-tubule network more developed - as AP spreads channels on cell membr open allowing influx of extracellular Ca - interacts w/ ryano receptors on SR - more Ca influx wia CICR

Question 2

repolarization of cardiac tissue

Answer 2

channels close - Ca pumped into extracellular matrix and SR

Question 3

resting potential of contractile myocardium

Answer 3

-85 to -95 mv

Question 4

depolarization of contractile myocardium caused by

Answer 4

1. fast Na+ channels
2. slow channels (L-channels, Ca)
   cause “plateau effect” of AP

Question 5

importance of Plateau effect in myocardium

Answer 5

prevents summation of twitches (duration of AP = duration of twitch)

Question 6

repolarization of contractile myocardium

Answer 6

caused by closing of slow channels and opening of K+ channels

Question 7

pacemaker cells

Answer 7

capable of spontaneous and rhythmic depolarization

Question 8

resting potential at SA node

Answer 8

-55 mV

Question 9

how does electrical excitation at SA node spread

Answer 9

gap junctions
electrical resistance lower than rest of membrane

Question 10

why are heart contractions staggered

Answer 10

ventricles need to fill before they can contract to make the most efficient pump

Question 11

what causes delay in atrial/ventricular contraction

Answer 11

delay in spread of electrical activity from atria to ventricle via the AV node to AV bundle to bundle of His to purkinje fibers

Question 12

AV node

Answer 12

conducting cells at base of right atrium that crosses fibrous tissue

Question 13

How does heart incr CO

Answer 13

1. intrinsic regulation (ex. change in SV)
2. regulation by autonomic NS and hormones (HR and SV)

Question 13

cardiac output (Q) or (CO)

Answer 13

amt of blood ejected by each ventricle per min
CO = HR x SR

Question 14

chronotropic vs ionotropic

Answer 14

chronotropic - factors affecting speed of HR
ionotropic - factors affecting force of HR (SV)

Question 15

chronotropic factors

Answer 15

parasymp input decr HR
symp input incr HR
neural input affect AP conduction thru AV junction

Question 16

inotropic factors

Answer 16

ACh, NE
E increases contractility
Starlings law

Question 17

Starling’s Law

Answer 17

as end diastolic volume increase so does SV
force incr bc of change in length of sarcomeres and elastic recoil

Question 18

blood flow determining factors

Answer 18

1. pressure diff between 2 ends of vessel
2. resistance to blood flow (diameter of vessel, length, viscosity)

Question 19

BF

Answer 19

diff in pressure / resistance

Question 20

basic principles of controlling BF

Answer 20

1. to tissue - controlled in relation to tissue needs
2. CO regulated by sum total of local tissue flow - as EDV incr so does CO
3. arterial pressure can be regulated independently of local BF or CO control

Question 21

as A pressure decrease

Answer 21

restore by contstricting arterioles and contracting large veins

Question 22

vascular system order

Answer 22

arteries - arterioles - capillaries - venules - veins
pressure progressively decr

Question 23

Arteries

Answer 23

transport blood under high pressure to tissues
- strong elastic walls
- large w low resistance
- incr pressure vessels (changes during cardiac cycle)

Question 24

pulse pressure

Answer 24

difference between systolic and diastolic pressure

Question 25

MAP

Answer 25

considered average pressure during cardiac cycle MAP = DP + 1/3PP

Question 26

Arterioles

Answer 26

small branches of arterial system - strong muscular walls - act as control valves - high pressure vessels - resistance to BF regulated by smooth muscle

Question 27

Arterial smooth muscle control

Answer 27

Local - decr O2, incr CO2, incr H+ cause vasodilation and decr resistance Extrinsic Neural - symp NS cause vasodilation/constriction Extrinsic Hormonal - E can cause either vasoconstriction/dilation

Question 28

Capillaries

Answer 28

allows exchange of gasses, nutrients, and metabolic byproducts between blood and tissue - thin walls, not elastic, no smooth muscle - small diameter - walls very permeable - flow rate lower = higher transit time - substance pass via simple diffusion

Question 29

Venules

Answer 29

diameters greater than those of caps and arts - walls thinner and weaker than arteriole - pressure much less so they can significantly contract

Question 30

Veins

Answer 30

return blood to heart - low resistnance due to incr diameter and compliance of walls - avg pressure around 10 mm Hg - walls have little smooth muscle

Question 31

how do veins regulate pressure and return to heart

Answer 31

smooth muscle innervated by symp NS, venous (muscle) pump

Question 32

rate of venus return and CO

Answer 32

as total BF demand inc so mus venus return

Question 33

blood make-up

Answer 33

plasma - liquid component 55% total vol erythrocytes - rbcs 45% total vol "buffy coat" - leukocytes, platelets

Question 34

Albumins

Answer 34

most abundant plasma protein formed in liver binding/carrier proteins

Question 35

globulins

Answer 35

clotting, enzymes, antibodies

Question 36

fibrinogen

Answer 36

blood clotting

Question 37

Leukocytes (WBCs)

Answer 37

immune response - monocytes, neutrophils, macrophages, lymphocytes

Question 38

Platelets

Answer 38

cell fragments involved in clotting

Question 39

Erythrocytes (RBCs)

Answer 39

transport O2 from lungs to tissue - H ct = 45% in males 42% in females - small and easily deformed - biconcave disk

Question 40

Hb

Answer 40

carries O2 4 subunits Fe-containing heme and polypeptide chain

Question 41

Growth and formation of RBC

Answer 41

1. stem cells in bone marrow 2. diff into proerythroblasts 3. continue to dif - produce Hb, shrink nucleus and extrude, lose other organelles 4. leave marrow and enter circulation

Question 42

regulation of RBC formation

Answer 42

tissue oxygenation - EPO levels in kidneys

Question 43

RBC lifespan

Answer 43

apprx 120 days - cell becomes fragile and ruptures during passage thru capillaries (spleen) - Fe carried by transferrin to bone marrow where stored as ferritin

Question 44

Anemia

Answer 44

inadequate O2 carrying capacity bc 1. low Hct 2. low Hb content of RBC 3. combination