CV Physio

Question 1

what is the average pressure in the R ventricl?

Answer 1

20

Question 2

why do valves open and close?

Answer 2

bc of pressure gradient

• if pressure in L ventricle slightly greater than aorta, valve opens
• if aortic pressure greater- it closes

Question 3

Where are the electrodes on the heart?

Answer 3

on the inside

-less electricity bc they are close to the conduction system

Question 4

what is Wiggers diagram?

Answer 4

-represents the events that make up the cardiac cycle
mechanical (pressure, volume, flow)
electrical (ECG)
audio (heart sounds)

Question 5

what is the avg rate of the SA node?

Answer 5

60-100

Question 6

what is the avg rate of the AV node?

Answer 6

40-60

Question 7

what is the avg rate of the ventricular/purkinje system

Answer 7

20-40

Question 8

how does the NS effect the heart?

Answer 8

SNS: impacts HR directly and how ventricles contract
PNS: does NOT innervate vasculature

Question 9

what is chronotrophy

Answer 9

HR

Question 10

what is dromotropy

Answer 10

conduction velocity

Question 11

what is inotropy

Answer 11

contraction of myocardium

Question 12

what is lusitropy

Answer 12

relaxation of myocardium

Question 13

where are alpha 1 receptors located?

Answer 13

vascular smooth muscle

arteries, veins, iris

Question 14

what is the effect of alpha 1 receptors?

Answer 14

vasoconstriction

Question 15

where is the location of the alpha 2 receptor?

Answer 15

adrenergic nerve

Question 16

where are the beta 1 receptors located?

Answer 16

heart

Question 17

what do the beta 1 receptors do?

Answer 17

increase HR
increase contractility
increase conduction velocty

Question 18

where are beta 2 receptors located?

Answer 18

lungs

coronary arteries

Question 19

what do the beta 2 receptors do?

Answer 19

bronchodilation

vasodilation

Question 20

Explain the first step of ECC and CICR

Answer 20

AP induced by pacemaker cells is conducted to contractile cardiomyocytes via conduction system and specifically by gap junctions

Question 21

Explain the 2nd step of ECC and CICR

Answer 21

as AP travels between sarcomeres, calcium channels in T-tubules are activated, which results in an influx of calcium ions into the cell through the l-type Ca channel

• initial cytosolic Ca is not sufficient to initiate contraction alone BUT triggers greater Ca release from SR
• also activates ryanodine receptors on SR which triggers ca release= CICR

Question 22

Explain the 3rd step of ECC and CICR

Answer 22

-Ca in cytoplasm binds to cardiac tronponin-C, which moves troponin-tropomyosin regulatory complex away from actin binding site.
actin is free to bind with myosin for muscle contraction ==ECC

Question 23

Explain the 4th step of ECC and CICR

Answer 23

intracellular Ca removed and stored by SR which decreases intracellular calcium concentration

Question 24

Explain the baroreceptor reflex

Answer 24

• important for BP monitering and maintenance
• pressure sensors
• act like a break: usually slowing you down
• LBP causes activation
• as receptors fire, fight or flight, SV increase, vasoconstriciton, BP increase
• imporatnt to prevent hypotension
• older=less sensitive

Question 25

Describe the Frank-Starling mechanism

Answer 25

a lenght-tension relationship | -ability of heart to change its force of contraction and therefore SV in reponse to venous return

Question 26

Describe the Treppe reflex

Answer 26

increases in HR result in increases in contractile force | -release more Ca

Question 27

Define preload

Answer 27

EDV

Question 28

define afterload

Answer 28

stress in wall of LV during ejection

Question 29

what are the functions of the pericardium?

Answer 29

- reduce friction - -stabilize/anchor heart in thorax - protect - enables greater SV/CO

Question 30

what is a buildup of fluid around the heart called?

Answer 30

pericardial effusion

Question 31

what happens to vasculature as we get older?

Answer 31

compliance changes | they become less compliant which means they are very stiff

Question 32

what is the #1 resistance to BF?

Answer 32

radius

Question 33

what would happen if the aorta becomes less compliant?

Answer 33

it becomes stiff and non-elastic so the LV has to develop more pressure. -it would increase the LV work and the heart would hypertrophy -as heart gets bigger, ventricular chamber gets smaller and can lead to heart failure cause not enough space to fill

Question 34

what are the functions of small arteries and arterioles?

Answer 34

- regulate BP by altering peripheral resistance | - regulate blood distribution to cap beds

Question 35

what is capillary flow porportional to?

Answer 35

velocity and surface area | -slow velocity enables exhcange to occur effecitvely

Question 36

what is the function of cappilaries?

Answer 36

- area of exhcange for gas, nutrients,waste | - pericytes

Question 37

what happens when caps become damaged?

Answer 37

become hihgly permable

Question 38

explain continous caps

Answer 38

most common some perm tight junctions

Question 39

explain fenestrated caps

Answer 39

more permeable

Question 40

explain discontinous/sinusoidal caps

Answer 40

most permeable | liver, spleen

Question 41

what is the function of veins

Answer 41

serves as reservoir for blood and some involved in exchange | -return blood to heart

Question 42

compare veins to arteries

Answer 42

veins have: - larger lumens - more collagen - thinner walls - less elastin - less smooth muscle fibers

Question 43

what is autoregulation

Answer 43

- ability of an organ to maintain a constant BF despite changes in perfusion pressure (ability to maintain constant flow when pressure is variable) - important with brain and kidney too

Question 44

what is MAP

Answer 44

"organ perfusion pressure" - avg BP during single cardiac cycle - should be greater than 60 mmHg to sustain organ perfusion normal=70-110 mmHg if MAP falls below 60, tissues wont get enough blood flow and organ ischemia may happen