Exsc Physiology Section 2

Front 1

how does increasing sympathetic stimulation increase SV?

Back 1

NE binds to B1 receptors which release more Ca^2+

Front 2

since we cannot recruit more cells to produce a stronger contraction, how do we do it? what are the 3 things?

Back 2

we need to have greater
1- increase contractility
2- increaes preload
3- decrease afterload

Front 3

what is preload?

Back 3

it is the stretch of myocardium. and this is caused by venous return.

Front 4

what is afterload?

Back 4

it is the pressure in the aorta that RESISTS the opening of the aortic valve.

Front 5

what is afterload represented by?

Back 5

DBP

Front 6

what would happen if we had an increase in afterload?

Back 6

the aortic valve would open later and close sooner, resulting in a decrease in SV and Q

Front 7

what is venous return?

Back 7

the amount of blood returning to the right atrium from the systemic circulation.

Front 8

what are the 4 things that cause an increase in venous return (or a decrease in venous pooling)?

Back 8

1- venoconstriction
2- muscle pump
3- cardiac output
4- thoracic pump

Front 9

what is the main concern for diastolic hypertension?

Back 9

reduced cardiac output.

Front 10

cardiac output=

Back 10

HR * SV

Front 11

EF (ejection fraction)=

Back 11

SV/ EDV *100

Front 12

what is a good EF number?

Back 12

50-60%. So when about 1/2 of the volume is being ejected, that is pretty good.

Front 13

what does a low EF mean?

Back 13

low contractility, thus low cardiac performance.

Front 14

______ is a good diagnostic and prognostic tool. What does prognostic mean?

Back 14

EF

predicted value of health (death or survival)

Front 15

what are some things we might want to consider before deciding how to give the heart transplant to?

Back 15

age
accept/reject heart?
measure EF (if < 20%, heart transplant needed)

Front 16

do smooth muscles have the property of conductivity?

Back 16

yes--not all cells are innervated. They have Gap junctions.

Front 17

what type of innervation does smooth muscle have?

Back 17

Symp. only.(so has TONIC control)

Front 18

myosin filaments in SM are _____ and have ______ myosin heads.

is there a central bear zone?

why is all this important?

Back 18

longer
more
NO

it gives a longer range of contraction (vasoconstriction and vasodilation)

Front 19

ARTERIES

are arteries high/low compliance?

Back 19

LOW

Front 20

why low compliance?

Back 20

we don't want arterial pooling

Front 21

what are the different levels of arteries?

Back 21

Aorta
artery
arterioles
capillary

Front 22

why does the aorta have an elastic membrane?

Back 22

because it needs to withstand CHANGES in BP.

Front 23

how many layers of tissue in the aorta?

Back 23

3

Front 24

why doesn't DBP just drop to 0? Why still pressure?

Back 24

because that elastic membrane rebounds and helps maintain pressure.

Front 25

what is pulse pressure =

Back 25

SBP-DBP

Front 26

what is blood flow like up in the aorta and arteries?

Back 26

pulsatile

Front 27

what is the blood flow like down in the capillaries?

Back 27

non-pulsatile (smooth continuous blood flow)

Front 28

arterioles are known as _______ vessels

Back 28

resistance.

Front 29

are arterioles innervated by symp?

Back 29

Highly. This helps to vasoconstrict and vasodilate which helps regulate blood flow which in turn determines BP.

Front 30

what is an example when we need to change BP?

Back 30

all the time. Even when changing posture.

Front 31

if we faint a lot when standing up or changing posture, what is this called?

Back 31

orthostatic hypotension.

Front 32

capillaries are also known as _______ vessels

Back 32

exchange.

Front 33

do capillaries have smooth muscle?

Back 33

NO. just have endothelial cells (this allows for better exchange)

Front 34

T/F Can capillaries vasoconstrict/vasodilate?

Back 34

NO

Front 35

the precapillary spincters are wrapped around the beginning of each capillary.

How do they constrict/open to the bed of capillaries?

Back 35

through LOCAL CONTROL.

Front 36

what are the 4 factors that define local control?

Back 36

1- pH
2- pCO2
3- p)2
4- Temp

Front 37

what will these 4 things do that will cause the spincters to open?

Back 37

low pH
high pCo2
low pO2
high temp

Front 38

so...Local control is controlled by ________ _______ of the organ tissue

Back 38

metabolic demand.

Front 39

so local control helps prioritize blood flow where?

Back 39

to more metabolically active tissues.

Front 40

what do we have to prioritize?

Back 40

because we don't have enough blood. (we only have 5L of blood in us)

Front 41

Veins are _____ compliant

Back 41

highly

Front 42

what does compliant mean?

Back 42

refers to extensibility (means that they can expand easier).

Front 43

what causes the veins to extend?

Back 43

Blood pressure.

Front 44

at rest, how much of our blood volume is in veins?

Back 44

2/3 (pooling)

Front 45

so we have that graph showing the blood pressure from the aorta to the capillaries. If we draw a line down the center of the graph, what does that line represent?

Back 45

MAP (Mean Arterial Pressure)

Front 46

where is SBP measured?

Back 46

it is the BP in the arterial side during ventricular systole.

Front 47

where is DBP measured?

Back 47

it is the BP in the arterial side during ventricular diastole.

Front 48

what does blood flow?

Back 48

due to pressure gradients.

Front 49

MAP=

Back 49

DBP+ 1/3(PP)

Front 50

so mean arterial pressure is the mean...

Back 50

driving force of blood through circulation.

Front 51

what is the normal MAP at rest?

Back 51

93

Front 52

where is MAP measured?

Back 52

between the aorta and the large arteries.

Front 53

when blood is coming BACK to the heart, what is MAP?

Back 53

pretty close to 0

Front 54

why does MAP go up during exercise?

Back 54

because cardiac output goes up.

Front 55

so how can we say that cardiac output goes up? What happens to SBP and DBP during exercise?

Back 55

SBP goes up
DBP goes down.

Front 56

why does DBP go down?

Back 56

because TPR (Total Peripheral Resistance) decreases.

Front 57

why does TPR decrease during exercise?

Back 57

because of vasodilation to sk. mm.

Front 58

so the normal Q at rest is 5L/min, and normal MAP is 93. What is TPR?

Back 58

18.6

Front 59

why else does TPR decrease during exercise?

Back 59

because within active sk. mm , capillary beds open due to LOCAL CONTROL.

So total cross sectional area of arteries increases. This causes a decrease in blood flow.

Front 60

TPR=

Back 60

MAP/Q

Front 61

now so during exercise, what is going to happen to TPR?

Back 61

it is going to decrease (for example, it will go from 18.6 (rest) to 4 (during exercise)

Front 62

and why again do we get this decrease in TPR?

Back 62

because of opening of capillary beds in active sk. mm and total increase in cross sectional area.

Front 63

be able to do these calculations!

Back 63

and be able to explain why it's happening too.

Front 64

Where does h2O come from when we sweat?

Back 64

from the blood plasma.

Front 65

what happens if we don't replenish this water?

Back 65

cardiac output goes down. (and the ability to perform goes down)

Front 66

how much water can we loose before performance goes down?

Back 66

2%.

Front 67

how long does it take to loose 2% of body water?

Back 67

can happen in less than an hour.

Front 68

what percentage of the blood is RBC? (hematocrit)

Back 68

45%

Front 69

what is the O2 carrying part of blood?

Back 69

hemoglobin.

Front 70

how many oxygens can a hemoglobin carry?

Back 70

4.

Front 71

on what part of the hemoglobin carries the oxygens?

Back 71

the irons. (not the globin part)

Front 72

how much Hb per dL of blood?

Back 72

15g

Front 73

when hemoglobin saturated with oxygen, how much O2 can be carried?

Back 73

1.34 mL O2/g Hb

Front 74

so what is the oxygen carrying capacity of blood?

Back 74

20.1 ml O2/dL

Front 75

normally, Hb is only 97% saturated, so what does this number come to?

Back 75

19.5 mL O2/dL