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1

What are the 2 main divisions?

pulmonary (low pressure) and systemic (high pressure)

2

What are the 4 components of each division?
Describe each

Pump: generates energy (atria and ventricles)
Distribution: arteries and arterioles
Exchange: capillaries, via diffusion and ultrafiltration
Collection reservoir: venules and veins (80%)

3

Define: Blood Flow

volume of blood that moves past a particular point per unit time
F = (P1-P2)/R

4

What are the two components that determine flow?

blood pressure and resistance

5

What are the three factors that contribute to changes in pressure?

frictional forces, vessel diameter, vessel length

6

What is the point of having direct electrical coupling between myocardial cells?

to allow for rapid impulse conduction and depolarization across the myocardium

7

How is the cardiac action potential different from a skeletal action potential?

it is much broader

8

Describe the autonomic and hormonal control of the cardiac system.

Preganglionics: nicotinic, acetylcholine
Postganglionic: muscarinic (para), acetylcholine, alpha or beta adrenoreceptors, norepinephrine
Hormones: RAAS, vasopressin, epinephrine (adrenal medulla)

9

The resting membrane potential (RMP) of cardiac myocytes is primarily a function of __________. This ion is drawn into the cell by the presence of ________.

its high permeability to K+ and low permeability to other ions (Na+ and Ca2+)
large negatively charged proteins (A-)

10

What happens to the resting membrane potential (RMP) when you: increase extracellular K+

increases (depolarization)

11

What happens to the resting membrane potential (RMP) when you: increase extracellular Na+

no change (because channels are closed; will lead to a higher peak potential when channels do open)

12

What happens to the resting membrane potential (RMP) when you: increase extracellular Ca 2+

no change

13

Why is the myocardial action potential so much longer than skeletal muscle?

there is an influx of Ca 2+ during depolarization in addition to the Na+ and, Ca 2+ channels open and close slowly compared to Na+

14

What are two types of AP's and where are each of them found?

Fast type: atrial and ventricular myocytes and Purkinje fibers; rate of rise is fast due to fast type Na+ channels
Slow type: pacemaker cells of SA and AV nodes; conduction velocity slow due to "funny" type Na+ channels

15

Describe the 5 phases of fast type action potentials

Phase 0: Rapid depolarization- rapid influx of Na+ (fast type channels numerous on myocardial cells, open/close quickly)
Phase 1: Transient repolarization- Na+ channels rapidly close and K+ currently activated
Phase 2: Plateau phase- slow type Ca 2+ channels begin to open and large influx into cell, gradually close
Phase 3: Rapid repolarization- K+ flows out as channels open, hyperpolarization
Phase 4: Resting membrane potential- previous changes fixed by Na+/K+ ATPase, Ca 2+ changes fixed by both Na+/Ca 2+ exchanger and reuptake of Ca 2+ into sarcoplasmic reticulum

16

What is the point of an extended refractory period?

allows for adequate filling time and enough time for sufficient Ca 2+ reuptake

17

When is the absolute refractory period? The relative?

Abs: phases 1-2
Rel: phase 3

18

Phase 2 of the cardiac action potential is:
a) absent in the fast type action potentials
b) dependent upon an increase in Ca 2+ conductance
c) dependent upon an increase in K+ conductance
d) prolonged in slow type action potentials
e) dependent upon an increase in both Ca 2+ and K+ conductances

B) dependent upon an increase in Ca 2+ conductance

19

Fast response cardiac action potentials are normally found in:
a) SA nodes
b) Purkinje fibers
c) AV node
d) Ventricular myocardium
e) B & D

E) B & D

20

With your knowledge of the ventricular cardiac myocytes and Nernst equation (Ek= -61.5 log ([K+]i/[K]o)), an increase in extracellular Ca 2+ should result in:
a) a more positive equilibrium potential for Ca 2+
b) a more negative equilibrium for K+
c) hyperpolarization of the resting membrane potential
d) depolarization of the resting membrane potential
e) B & D

A) a more positive equilibrium potential for Ca 2+

21

What is the effective refractory period? When does it occur?

period cell is effectively refractory but a local action potential can be stimulated with no propagation
happens during beginning of phase 3

22

Cardiac action potentials are described as slow versus fast. This difference is primarily based on the rate of rise of the membrane potential in phase 0. Phase 0 in the slow type action potential is primarily dependent upon:
a) the opening of a "funny" Na+ channel
b) the closing of a fast Na+ channel
c) the opening of a slow voltage dependent Ca++ channel
d) the opening of Ca++ activated K+ channels
e) the presence of inward rectifying K+ channel

c) the opening of a slow voltage dependent Ca++ channel

23

Relative to Phase 4, Na+ conductance during Phase 0 in the slow type cardiac action potential is:
a) increased
b) decreased
c) unchanged
d) i don't know
e) only Dick Cheney knows for sure :)

b) decreased

24

Increased levels of circulating catecholamines will have the following effects on cardiac function:
a) a decreased heart rate & contracility
b) a decrease in "funny" Na+ current conductance
c) an increase in "funny" Na+ current conductance
d) more negative maximum diastolic potential
e) what's a catecholamine?

c) an increase in "funny" Na+ current conductance
examples of catecholamines include epinephrine and norepinephrine, which increase contractility

25

Calculate the heart rate if the P-P interval on the ECG is 225 ms.
a) 57 bpm
b) 85 bpm
c) 125 bpm
d) 227 bpm
e) 267 bpm

e) 267 bpm
1000 ms/225 ms =4.4444 beats per second
4.4444 beats per second x 60 seconds per minute

26

Acetylecholine directly influences cardiac output by:
a) binding to beta-1 receptors in the AV node
b) moving the maximum diastolic potential of the SA node to a less negative potential
c) binding to muscarinic receptors in the SA node
d) decrease K+ conductance
e) increasing "funny" Na+ conductance

c) binding to muscarinic receptors in the SA node

27

With your knowledge of the ventricular cardiac myocytes and the Nernst equation (ECa++ =-log([Ca++]i/[Ca++]o), an increase in extracellular Ca++ should result in:
a) a more positive equilibrium for Ca++
b) a more negative equilibrium potential for K+
c) hyperpolarization of the resting membrane potential
d) depolarization of the resting membrane potential

a) a more positive equilibrium for Ca++

28

The best treatment for second degree AV nodal blockade is:
a) cholinergic agonist
b) alpha-2 receptor antagonist
c) muscarinic agonist
d) muscarinic antagonist
e) increased carrot intake

d) muscarinic antagonist
Muscarinic antagonist ex.- atropine, increases sympathetic drive to the heart, increases HR

29

An ectopic pacemaker in the left ventricle could potentially result in:
a) increased duration of the P wave
b) increased number and increased duration of QRS waves
c) increased interval between R waves
d) decreased number of QRS waves in the ECG

b) increased number and increased duration of QRS waves

30

A normal sinus arrythmia may be characterized by:
a) an increase in heart rate during inspiration
b) an increase in parasympathetic drive during inspiration
c) an increase in heart rate during expiration
d) sinus arrythmias are not normal

a) an increase in heart rate during inspiration