blood flow and innervation

Question 1

Sympathetic nervous system

Answer 1

innervation widespread to all areas of heart

Question 2

Parasympathetic NS

Answer 2

innervation of SA and AV nodes by vagus nerve

Question 3

SNS effect

Answer 3

chronotropic: increase HR
dromotropic: increase speed of conduction
inotropic effect: increase force of contraction
iusitropic: relax more quickly
– release of NE, binds to B receptors
— -> increased cAMP

Question 4

PSNS effect

Answer 4

decrease HR
decrease speed of action potential conduction
- ACH binds to muscarinic receptors
– inhibits cAMP
– increases K permeability: increased efflux
increase vagal stimulation -> dec. HR
– vasovagal response: dizzy, fainting

Question 5

blood flow determined by

Answer 5

driving pressure

vascular resistance

Question 6

ohm’s law

Answer 6

increased driving pressure (P) -> increased blood flow (Q)
increased resistance (R) -> decreased blood flow (Q)
Q= P/R

Question 7

coronary blood flow: driving pressure

Answer 7

determined by aortic BP and right atrial pressure

• inc. aortic BP -> increased coronary blood flow
• increased right atrial pressure -> decreased coronary blood flow

Question 8

coronary blood flow: vascular resistance

Answer 8

2 determinants

• coronary artery diameter
• external compression r/t myocardial contraction/relaxation

Question 9

vessel autoregulation

Answer 9

intrinsic ability of arteries to adjust bloodflow r/t tissue needs

Question 10

SNS and vessel

Answer 10

NE binds to A1-> vasoconstriction

NE binds to B2 -> vasodilation

Question 11

CO =

Answer 11

HR x SV

Question 12

SV influenced by

Answer 12

preload
contractility
afterload

Question 13

preload

Answer 13

volume in heart

Question 14

afterload

Answer 14

resistance of vasculature

Question 15

SNS activated by

Answer 15

inadequate blood pressure, lack of O2, buildup of metabolic end products

Question 16

baroreceptors

Answer 16

in arotic arch and corotid arteries

• respond to change in BP -> transmit info to CNS via CN IX, and X
• dec. BP -> PSNS inhibition and cardiac SNS activation -> increased HR
• increased BP -> PSNS activation and SNS inhibition

Question 17

Bainbridge reflex

Answer 17

sensory fibers within heart chanbers

• respond to chang in intrachamber pressure (blood volume)
• over distention -> dec. PSNS and inc. HR

Question 18

end diastolic volume

Answer 18

blood in ventricles just before contraction

- ventricles usually eject 60-70% , while 30-40 remains in ventricle

Question 19

Frank starling law (length-tension relationship)

Answer 19

increased preload (blood volume) -> increased stretch -> increased force of contraction

• stretching of muscle fiber -> myosin and actin more closely aligned, more cross bridge formation -> stronger contraction
• only works to a certain point, then plateaus

Question 20

contractility 3 factors

Answer 20

amounts of contractile proteins in muscle cell
availability of ATP
availability of free Ca

Question 21

cardiac workload

Answer 21

hearts O2 requirements/ ATP requirements

Question 22

Poiseuille’s Law

Answer 22

resistance = viscosity x length x 8/ radius
greatest resistance to blood flow is vessel radius and length
- greatest resistance in the smallest vessels; arterioles

Question 23

velocity and cross sectional area

Answer 23

branching of arterial vessels increases total cross-sectional area and thus dec. velocity of blood flow

Question 24

laminar flow

Answer 24

streamlined, blood flows smoothly.
walls slow flow.
fastest in middle

Question 25

turbulent flow

Answer 25

results from pathologic conditions
- coarctation (narrowing)
- valvular abnormalities
- low blood viscosity (anemia)
Associated with murmurs or bruits
Produces increased pressure gradient

Question 26

S1/ lub

Answer 26

ventricular contraction/ systole

- blood hitting AV valves causes them to close

Question 27

S2/ dub

Answer 27

atrial contraction
ventricular filling
- blood against semilunar valves causing them to close.

Question 28

S3

Answer 28

increased blood volume
stiff chordae tendineae 
heart failure
"kentucky" gallop
- blood hitting other structures within ventricle

Question 29

S4

Answer 29

Atrial Kick
turbulent blood flow against stiffened ventricular walls
atrial contraction trying to overcome hypertrophic ventricle
“tennessee” gallop

Question 30

Increased contractility

Answer 30

NE
not r/t blood volume
r/t number of contractile proteins
allows for ejection of more blood

Question 31

increased afterload

Answer 31

ventricle has to overcome more pressure

• > decreased SV ejected
• aortic valve closes sooner d/t increased BP

Question 32

Cardiac myocytes

Answer 32

2 types

• working cells: mechanical pumping function
• electrical cells: transmit electrical impulses

Question 33

differentiated myocytes

Answer 33

unable to proliferate
- increase in size
- increase contractile proteins
stem cells -> myocyte to create moree

Question 34

intercalated disk

Answer 34

joins 2 sarcolemmas, contains gap junctions

Question 35

functional syncytium

Answer 35

separate cells working together

Question 36

Striation of cardiac cells

Answer 36

d/t structure of proteins (myofibril) of contractile apparatus

• myosin
• actin
• • titin: hold myosin filaments in place

Question 37

ANP

Answer 37

atrial natriuretic peptide

- released from myocytes in response to atrial stretch (inc. BP)

Question 38

BNP

Answer 38

B-type natriuretic peptide

- released from ventricular myocytes r/t chronically over distended ventricles

Question 39

ANP and BNP cause

Answer 39

Na and H2O excretion in kidneys

- renin-angiotensin-aldosterone system antagonist