Cardiac Anatomy

Question 0

What’s the largest venous channel

Answer 0

Coronary sinus

Question 1

Parietal portion…

Answer 1

Adheres to fibrous pericardium

Question 2

What is left atrium responsible for

Answer 2

20-30% LVEDV via the atrial kick

Question 3

Characteristics of myocardium and types

Answer 3

Skeletal and smooth muscle

• epicardium - outer
• myocardium - middle
• endocardium- inner
• subendocardium - the greatest risk for MI

Question 4

When is each ventricle supplied?

Answer 4

LV - diastole

RV - both systole and diastole

Question 5

ventricular cells

Phase 0

Answer 5

Na influx,
Depolarization
Gates open at -70 to -65 mV

Question 6

Ventricular cells

Phase 1

Answer 6

Initial repolarization
K efflux
Na closed
Ca slowly in
Overshoot 20 to 30

Question 7

Ventricular cells

Phase 2

Answer 7

Plateau

Ca channels are open

Question 8

Ventricular cells

Phase 3

Answer 8

Rapid repolarization
K efflux
Ca inactivated

Question 9

Ventricular cells

Phase 4

Answer 9

Resting potential

Na/K pump restored

Question 10

Absolute refractory

Answer 10

No stimulation can cause another AP

First part of the refractory period

Question 11

How does relaxation occurs in phase 4

Answer 11

Ca is actively pumped back into the sarcoplasmic reticulum by Ca, Mg, ATPase

Question 12

Relative refractory period

Answer 12

Possible to cause another AP, but the intensity of the cantor action will be relative to the time in this period

Question 13

Refractory period

Answer 13

Minimal interval between two depolarizing impulses that are propagated

Question 14

Characteristics of Atrial and Ventricular APs

Answer 14

Fast
RMP -80 to -90 mV. Resting membrane potential
Bigger upstroke, faster conduction
Occurs: atria, ventricles, purkinje

Question 15

SA & AV node AP

Answer 15

Slow
RMP -55 to -60 mV due to slow leak of Ca++
Th ESA & AV nodes are pacemaker cells
No plateau, just phases 4, 0, 3 since NO rapid depolarization
Slow phase 4 depolarization

Question 16

What is compliance of ventricle

Answer 16

Relationship between LVEDV & LVEDP

Volume & pressure

Question 17

What will increase inotropy

Answer 17

PNS inhibition
SNS activation
Circulating catecholamines 
HR -- Bowditch effect
Afterload -- Anrep Effect

Question 18

Cardiac innervation

Answer 18

SNS: greater effect on contractility
T1-T4, cardiac plexus, SA node, muscle, Inc HR

PSN: predominates, Vagus X
Originate in the Medulla, dec HR/contractility
R Vagus innervates SA node
L Vagus innervates AV node

Question 19

Cardiac reflexes

Answer 19

1. Afferent n sense a change— sends info to brain
2. Brain processes & implamants appropriate response
3. Efferent n. activity is altered, homeostatic response

Question 20

Where are Baroreceptors

Answer 20

Afferent
Carotid sinuses: dominant: travel via n. Herring branch of CN IX
Aortic arch: secondary. T ravel by aortic n.

Question 21

Marey’s law

Baroreceptor reflex

Answer 21

Inc BP - inc stretching - HR reflex dec

Response to local stretch

Question 22

Bainbridge reflex

Answer 22

True reflex rather than a response to local stretch
Incr in preload directly stretches the SA-incr SA node automaticity/HR

Inc filling will incr HR, except if HR was high

Question 23

Respiratory reflex

Answer 23

Receptors are in the medulla
Inspiration: inc HR,
expiration: decrease HR

Question 24

Determinants of myocardial O2 supply

Answer 24

Coronary artery anatomy
Diastolic pressure
Diastolic time
Arterial O2 content Hgb 
O2 extraction

Question 25

Determinants of myocardial O2 demand

Answer 25

HR
Myocardial contractility
Myocardial wall tension: preload, afterload

Question 26

What is EF

Answer 26

EF: fraction of the EDVV that is ejected
Way to evaluate the inotropoic state of the heart

EF= (SV/EDV) x 100%

Question 27

CPP=

Answer 27

CPP = Diastolic BP - PAWP

Question 28

SVR

Answer 28

SVR = (MAP-RAP) x 80/CO

Question 29

MAP

Answer 29

MAP = SBP + (DBP x 2)/ 3