CVD Phys II

Question 1

what is avn conduction and what is the speed of it

Answer 1

excitation wave that spread rapidly thru atria converging on AVN thru interatrial pathways

-slowest conduction velocity

Question 2

Ventricular myocardium conduction- speed

Answer 2

Conduction thru left wall is slower than right wall due to thickness of the wall

Question 3

Atrial and ventricular activation (+ delays)

Answer 3

atrial activation occurs in .09 s
then .16 sec delay
ventricular activation occurs in .23 sec

Question 4

What 3 drugs reduce conduction rate

Answer 4

Beta blockers
Calcium channel blockers
Digitalis

Question 5

What is positive dromotrophic and negative dromotrophic effect

Answer 5

pos- increases conduction velocity in av node via b receptors

neg- decreases conduction velocity in av node

Question 6

What is sinus tachycardia caused by

Answer 6

• increased sympathetic stim in stress/ex
• increased body temp
• low blood pressure
• hyperthyroidism

Question 7

What is sunus bradycardia caused by

Answer 7

• increased vagal tone

- hypothyroidism

Question 8

What is extrasystole and what is it due to

Answer 8

A beat that occurs before expected next normal beat

-heavy stress/ caffeine use

Question 9

What is atrial flutter

Answer 9

atrial rates bw 250-350 bpm

Question 10

What is the cause of atrial fibrillation

Answer 10

atrial activity bw 350-500bpm

Question 11

What is the most dangerous fibrillation

Answer 11

ventricular fibrillation

-cant effectively pump blood/ no contraction

Question 12

What occurs in a bundle branch block

Answer 12

Blockage of one side will result in one ventricle contracting a fraction of a second later than the other

Question 13

What occurs in wolff parkinson white syndrome

Answer 13

Extra electrical pathway in the heart which allows early activation of a portion of one ventricla (can lead to periods of tachycardia)

Question 14

What is the P wave and PR segment

Answer 14

P- depolarization of R+L atria

PR- AV nodal delay (conduction of atria to ventricles)

Question 15

What is the QRS segment

Answer 15

Ventricualr depolarization

Question 16

What is the St segment

Answer 16

Plateu phase of heart

Question 17

What is the t wave

Answer 17

Ventricular repolarization

Question 18

What occurs during ventricular filling and what is the amount of blood in the ventricles called at this point

Answer 18

Atrial systole

• Semilunar valves closed
• End diastolic volume

Question 19

What is the 2 stages of the ventricular systole stage and what is the amount of blood left called

Answer 19

isovolumetric stage-ventricles begin to contract while semilunar valves still closed

Ejection phase- pressure rises and semilunar valves open

_ called end systolic volume

Question 20

What occurs in early diastole

Answer 20

atria and ventricles in diastole

• semilunar valves close
• antri ventricular valves open allowing some blood to leave the atria (passive ventricular fillinG)

Question 21

How long does the heart spend in diastole and systole

Answer 21

2/3 time in diastole

1/3 in systole

Question 22

What is stroke volume

Answer 22

EDV-ESV=SV

Question 23

What is the frank starling law

Answer 23

esentially prelode

- when there is more blood in ventricles the cardiac mm is streched leading to increased tension development

Question 24

What is preload and what does it result in

Answer 24

The degree of strecth of cardiac mm cells before they contract (increased preload ejects more blood so ESV is lower)

Question 25

What is afterload

Answer 25

related to teh pressure that ventricle must generate in order to eject blood into the aorta

Question 26

what is the frequency force relationship

Answer 26

cardiac muscle responds to high rates of stim by progressively greater forces of contraction (increases SV up to 180bpm)

Question 27

How does sympathetic stim influece calcium in heart

Answer 27

1. increasees ca entry from ECF thru activation of l typeca channels and frequency force relation
2. Increase ca release from SR (due to first effect)