Cardiovascular Physiology

Front 1

lattice work of dividing and recombining cardiac myocytes
- some cytoplasm continuous
- atrial and ventricular are separated from each other

Back 1

syncytiums

Front 2

undulating double membranes which connect cardiac myocytes along longitudinal axis

- gap junctions for electrical synapses for AP conduction

Back 2

intercalated discs

Front 3

similarities and differences between skeletal and cardiac muscle?

Back 3

- cardiac have more mitochondria

- sarcomere organization is similar - both striated

- cardiac m needs both extracellular and SR Ca for contraction

Front 4

Steps in excitation-contraction coupling

Back 4

1. AP from contractile cell
2. plateau phase - Ca2+ rushes into cells (L-type)
3. Ca2+ induced Ca2+ release from SR
4. intracellular Ca2+ level rise - Ca2+ inds to troponinC
5. troponin pushes tropomyosin to expose myosin binding site on actin

Front 5

magnitude of tension produced by cross-bridge cycling is proportional to...

Back 5

intracellular Ca2+ level

Front 6

relaxation mechanism Ca 2+ is removed in what 2 ways?

Back 6

1. Ca2+ pumped into SR by Ca2+ ATPase

2. Ca2+ is moved back into ECF via Ca2+ ATPase AND Ca2+ exchanged for Na+ (secondary)

Front 7

SANS effect on inotropism (contractility)

Back 7

- increased peak tension
- increased rate of tension
- shortened contraction time
- increased Ca entry
- E and NE on B1

Front 8

PANS effect on inotropism (contractililty)

Back 8

- ATRIA ONLY
- Ach on M2
- decreased Ca2+ entry

Front 9

positive inotropism factors

Back 9

* increased HR - more Ca build up
* cardiac glycosides - inhibit Na/K ATPase, leaves more Ca in cell

Front 10

negative inotropism factors

Back 10

* Beta 1 blockers
* Ca2+ channel blockers
* heart failure
* acidosis
* hypoxia
* hypercapnia

Front 11

why does the F-S relationship work with optimal myocyte length for producing tension?

Back 11

cardiac muscle is relatively stiff

Front 12

what is preload?

Back 12

ventricular end-diastolic pressure
- amount of blood that has filled the L ventricle at the end of diastole right before contraction

Front 13

what is afterload?

Back 13

aortic pressure
-force against which left ventricle must eject blood
-left ventricle must exceed aortic pressure to open valve

Front 14

Stroke volume =

Back 14

SV = EDV - ESV

Front 15

ejection fraction =

Back 15

EF = SV/EDV

- fraction of EDV that is ejected by the ventricle
- 55-80%

Front 16

CO =

Back 16

CO = SV x HR

- volume of blood ejected from ventricle/min

Front 17

L ventricular contraction; mitral and aortic valves are closed

- volume constant
- increasing pressure (eventually opens aortic valve)

Back 17

isovolumetric contraction

Front 18

after building pressure in L ventricle exceeds aortic pressure
-aortic valve opens
-pressure rises until most blood leaves ventricle
-pressure falls, aortic valve closes

Back 18

ventricular ejection

Front 19

left ventricle relaxes
-mitral and aortic valves closed
- volume constant
- pressure drops

Back 19

isovolumetric relaxation

Front 20

pressure drops below atrial
- mitral valve opens
- volume increases
- pressure increases slightly
- when pressure exceeds atrial, mitral valve closes

Back 20

ventricular filling

Front 21

what does increased preload do?

Back 21

F-S
- increased EDV
- increased contractility
- increased stroke volume

Front 22

what does increased afterload do?

Back 22

- harder for left ventricle to eject blood
- decreases stroke volume
- increases ESV

Front 23

what does increased contractility do?

positive ionotropism

Back 23

increased SV
decreased ESV

Front 24

CO =

related to oxygen consumption
Fick's

Back 24

CO = total O2 consumption/ [O2]pv - [O2]pa

Pulmonary vein can be sampled by peripheral artery

Front 25

3 assumptions of using Fick principle

Back 25

1. CO of R heart = CO of L heart
2. rate of O2 consumption = amount of O2 leaving lungs - amount of O2 coming back
3. can also be used for measuring blood flow in individual organ systems

Front 26

when does atrial systole occur?

Back 26

during the end of ventricular diastole - most of the blood has already flowed into ventricles since AV valve is open before atrial contraction

Front 27

EKG are electrical events and will _______ mechanical events

Back 27

EKG events precede mechanical events

Front 28

1st heart sound

Back 28

1. closure of AV valves
- normal
- possibly split, mitral closes first

Front 29

2nd heart sound

Back 29

2. closure of semilunar valves
- normal
- possibly split, aortic closes first

Front 30

3rd heart sound

Back 30

rapid flow of blood from atria to ventricles
- normal in children
- adults - indicates CHF

Front 31

4th heart sound

Back 31

atrial contraction
- occurs with high atrial pressure or ventricular hypertrophy
- sound of blood filling against a stiffened ventrical
- atrial kick

Front 32

what does the cardiac function curve represent?

Back 32

Right atrial pressure determines CO
- directly related
- F-S until stretched too much

Front 33

How does the cardiac function curve move?

what causes it?

Back 33

ROTATIONS

upward - SANS, LVH, positive ionotropism

downward - PANS, increased TPR (CO decreased) , negative ionotropism

Front 34

what does the vascular function curve represent?

Back 34

- inverse relationship between venous return and right atrial pressure

- decrease in pressure causes greater pressure gradient driving blood flow, greater VR

Front 35

what is the plateau in the vascular function curve?

Back 35

- VR increases to a point as RAP decreases
- levels off low pressure will cause collapse of veins in the chest

Front 36

venoconstriction does what to MSP?

Back 36

venoconstriction causes increased MSP

Front 37

How does the vascular function curve move?

What causes shift?

Back 37

SHIFTS RIGHT - increased blood volume & venoconstriction (decreased compliance)

Front 38

what causes the vascular function curve to rotate?

Back 38

ROTATES UPWARD - decreased TPR

ROTATES DOWNWARD - increased TPR

- MSP is unchanged in rotation!

Front 39

how do inotropic effect CV function curve?

Back 39

+ rotate cardiac function curve upward

- rotate cardiac function curve downward

Front 40

Arterial pressure is _____________________ in major arteries

Back 40

approximately equal

Front 41

equation for arterial pressure

Back 41

Pa = CO x TPR

- variables are dependent

Front 42

if Pa moves above or below ____ set point, changes are made in TPR, CO, or both

Back 42

100 mm Hg

Front 43

where are the baroreceptors located and which nerves do they follow?

Back 43

aortic arch - vagus

carotid sinus - glossopharyngeal

Front 44

where do the baroreceptors project to?

Back 44

NTS - medulla

Front 45

3 cardiovascular motor centers that the NTS directs messages to

Back 45

vasoconstrictor - increases SANS, vasoconstriction

cardiac accelerator - increases SANS, HR and contract

cardiac decelerator - increases PANS, HR (ATRIA ONLY)

Front 46

during a hemorrhage, decreased arterial pressure causes what?

Back 46

decreased arterial pressure, decreased baroreceptor stretch & firing rate, decreased PANS, increased SANS

Front 47

what stimulates renin release?

Back 47

decreased perfusion of renal arteries

Front 48

what does renin do?

Back 48

renin converts angiotensinogen to angiotensin 1

Front 49

what does angiotensin II do?

Back 49

- constrict arterioles
- thirst
- ADH release
- Na+ reabsorption
- aldosterone synthesis and release

Front 50

what does aldosterone do?

Back 50

Na+ reabsorption
- raise blood volume
- raise BP
- takes hours to days

Front 51

what are central chemoreceptors stimulated by?
where?
response?

Back 51

Medulla
- brain ischemia, increased CO2
- massive vasoconstriction in many vascular beds to increase BF to brain

Front 52

what are the peripheral chemoreceptors stimulated by?
where?
response?

Back 52

aortic and carotid bodies
- low PaO2 > 70 mm Hg
- vasoconstriction in many vascular beds

Front 53

what is ADH?

Back 53

from posterior pituitary
- stimulated by increased plasma osmolarity - low blood volume and pressure
- causes vasoconstriction and increases water reabsorption

Front 54

what is ANP?

Back 54

from atria
- stimulated bu increased atrial pressure
- causes vasodilation and increased water excretion