4. Cardiovascular Physiology IV

Question 1

What are pacemaker cells in the heart? (2)

Answer 1

• SA node

- AV node

Question 2

pacemaker cells depolarize by

Answer 2

an influx of Ca ions through Ca channels

Question 3

pacemaker cells repolarize by (2)

Answer 3

by inactivation of the Ca channels and by increased conductance of K

Question 4

pacemaker cells have a ____ RPM

Answer 4

less negative

Question 5

what determines the conduction velocity of pacemaker cells ___
this then causes more …

Answer 5

a less negative RMP which causes more inactivated Na h gates

Question 6

SA node has _____ & ____ in regards to the beating of the heart

Answer 6

Has automaticity (the ability to initiate own beat) & rhythmicity (the regular activity to beat)

Question 7

SA node is represented by … in a heart rhythm

Answer 7

the p wave or contractions of the atrium

Question 8

describe the AP of an SA node. RPM, upstroke, plateau, repolarization, & depolarization

Answer 8

• Has a less negative RMP
• Upstroke of AP is less steep
• Plateau not sustained
• Repolarization more gradual
• Slow diastolic depolarization during phase 4

Question 9

AV node is represented by …

Answer 9

• Represents the QRS complex or ventricle contractions

Question 10

What nervous system can increase conduction of AV node?

What can decrease conduction of AV node?

Answer 10

• SNS stimulation

- ACh in PNS can decrease conduction

Question 11

the AV node causes a delay in what 2 regions of the heart

Answer 11

AN and N region of the heart (where we get QRS)

Question 12

a heart arrhythmia where there is a problem with the atrium and reentry of electrical beats

Answer 12

Supraventricular Tachycardia

Question 13

a heart arrhythmia where there is A loss of the pacemaker activity resulting in irregular rhythm

Answer 13

Atrial Fibrillation

Question 14

a heart arrhythmia where there is Rate greater than 100bpm

Answer 14

Sinus Tachycardia

Question 15

a heart arrhythmia due to increase catecholamine release

Answer 15

Sinus Tachycardia

Question 16

a heart arrhythmia due sympathetic nerve predominance

Answer 16

Sinus Tachycardia

Question 17

an electrical impulse that travels in a circle within the heart instead of outward and then stopping

Answer 17

reentry phenomena

Question 18

which nervous system develops a slower and longer response

Answer 18

SNS

Question 19

in regards to BP baroreceptors do what?

Answer 19

o Respond to acute change in blood pressure

Question 20

the Atrial Sensory Receptors known as Brainbridge reflex increases what

Answer 20

blood volume cause increase HR

Question 21

• Myocardial fiber length determines

Answer 21

cardiac contraction

Question 22

o The more blood the ventricle is filled with during diastole => greater

Answer 22

volume of blood ejected during the resulting systolic contraction (SV)

Question 23

increased stretching of the myocardium of the heart leads to an enhanced

Answer 23

affinity of troponin C for Ca => increased force of contraction

Question 24

• Cardiac reflex is effected by

Answer 24

preload and after load

Question 25

- Frank Starling law Maintains a precise balance over

Answer 25

over time between the output of the left & right ventricles in a non-diseased heart

Question 26

Identify hormonal effects on the heart in the SNS: (3)

Answer 26

- Slow release of NE - Long degradation of NE - NE then involves 2nd messenger CAMP

Question 27

- The effect of SNS on hormonal effects is due to

Answer 27

the facilitation of Ca influx into cardiac cell

Question 28

- ACh stimulation of cholinergic receptors in the PNS leads to ... and activates...

Answer 28

- inhibited release of NE from sympathetic nerves | - Activates ACh regulated K+ channels

Question 29

the PNS stimulation causes the release of epinephrine which serves to

Answer 29

o Increases rate and force of contraction

Question 30

the PNS stimulation causes the release of Thyroid hormone which serves to enhance (2)

Answer 30

o Enhances cardiac contractility | o Enhances cardiac protein synthesis -> hypertrophy

Question 31

the PNS stimulation causes the release of insulin which serves to enhance

Answer 31

o Enhances cardiac contractility

Question 32

the PNS stimulation causes the release of glucagon which serves to enhance

Answer 32

o Increase rate and contractility

Question 33

o HR ___to blood pressure

Answer 33

inversely proportional

Question 34

in AP pacemaker cells transition to _____ is less distinct

Answer 34

phase 3

Question 35

in AP pacemaker cells the _____ is more gradual in slow response cells than fast

Answer 35

upstroke

Question 36

in AP pacemaker cells phase ____ is absent

Answer 36

- Phase 2

Question 37

in AP pacemaker cells phase ____- is not as prolonged as fast

Answer 37

- Phase 2

Question 38

- Fast response cells responsible for _____

Answer 38

conduction

Question 39

- Slow response cells responsible for pacemaker

Answer 39

pacemaker

Question 40

- Fast response cells need fast _____

Answer 40

Na channels

Question 41

- The speed of fast response cells is dependent on the ____

Answer 41

amplitude

Question 42

-The higher the ______ in fast response cells the more positive the inside of the cells is

Answer 42

amplitude

Question 43

- You can match the movement of the electrical activity of the heart when you look at an ___to identify what phase the electrical activity is at

Answer 43

EKG

Question 44

___ is represented by the P wave on EKG

Answer 44

SA node

Question 45

___ is represented by the PR inverval that is at the beginning of the QRS

Answer 45

o AV node

Question 46

___ is represented by the electrical activity going into the ventricles

Answer 46

o The QRS

Question 47

___ is represented by the ventrical repolarization and relaxation

Answer 47

o The T wave