CVD Phys I

Question 1

What do the atrioventricular and semilunar valves prevent backflow from

Answer 1

AV- prevent from ventricles to atria

Semilunar- prevent backflow into ventricals from pulmonary trunk and aorta

Question 2

What kinds of infection can cause inflamation in each layer of the heart and negative effects

Answer 2

endocarditis- bacterial/fungal (can destroy valves)

myocarditis- virus (lose ability to pump blood)

Pericarditis- bac/fungal/virus (sharp pain everytime heart expands)

Question 3

What is cardiac tamponade and what is it caused by

Answer 3

pericardial effusion (accumulation of fluid in pericardial cavity)
- pressure adversely affects heart function

Question 4

What is the function of the fibrous skeleton of the heart (2)

Answer 4

1. Acts as cardiac skeleton

2. Acts as electrical insulator between atria and ventricles

Question 5

What are the 3 specialized tissues that the heart contains

Answer 5

1. typical striated fibres
2. Autorythmic cells (sets hr)
3. Conductive tissue

Question 6

What are the 2 types of intercalated discs in the heart

Answer 6

1. Anchoring junctions (holds cardiac mm cells together)

2. Gap junctions- allows aps to travel

Question 7

What are the 4 properies of cardiac mm

Answer 7

1. Ecitability (ability to respond to stim)
2. Auto rhythmicity (ability to makes its own beat)
3. Conductivity (ability to transmit AP from one cell to another)
4. Contractility

Question 8

What are the 2 APs of the heart and where are they located

Answer 8

1. Membrane pot of autorythmic cells (in sa node etc)

2. Membrane pot of contractile cell

Question 9

What are the maor steps of AP in contractile myocytes

Answer 9

1. rapid opening of na channels
2. NA closes and K opens (k leaves)
3. Plateu- slow inward Ca current thru L type receptos keeps plateu
4. Ca close and K exits to return to -90

Question 10

What alows for the plateu in cardiac myocytes

Answer 10

almost effluc of k out of cell and slow inward ca influx thru voltage gated ca l type channels

Question 11

What is calcium induced calcium release and where does it happen

Answer 11

Ca enters t tubules dihydrpyrdine receptos and allows more ca release from sarcoplasmic reticulum

Question 12

Sequence of exitation thru heart

Answer 12

Sa- autorythmic
Internodal path to AV node
AV bundle to ventricles
left and righ bundles to purkije fibres

Question 13

Phases of pacemaker AP

Answer 13

1. Spontaneous flow of na thru slow na channels slowly depolarizes membrane
2. At -55mv transient ca channels open
3. -40 is depolarization (l type ca channels open)
4. repolarization (k channels open ) bringing it back to -60

Question 14

What is prepontential and why can it happen

Answer 14

autorythmic cells have unstable RMP caused by increased Na/ca permeability
-following each impulse RMP declines to firing level and demonstrated spontaneous depol

Question 15

What is overdrive suppression and what has it the most

Answer 15

SA node is dominant pacemaker becuase it has the highest rate of spontaneous automaticity (increase in both Na and ca permeability happens quickest)

Thus it has overdrive supression on other nodes

Question 16

what is the spontaneous firing rate of SAnode and what is it limited to and by what

Answer 16

normally 100bpm

limited to 60-90 by parasympathetic div ( r vagus n)

Question 17

What is the secondary pace maker and what inn it

Answer 17

AVN 45-60bpm (left vagus)

Question 18

what is the firing rate of the Purkinje and speed of conduction

Answer 18

25-40bpm

has the highest rate of conduction

Question 19

what is positive chronotropic and what is it due to

Answer 19

Leads to tachycardia (>100bpm)

-Sympathetic stimulation

Question 20

what is negative chronotropic and what is it due to

Answer 20

leads to braycardia (<60 bpm)

-parasympathetic stims

Question 21

What does hypercalemia and hypocalcemia lead to

Answer 21

hyper- iduces bradycardia (prevents full reactivation of pacemaker channels)

hypo- increases rate of depolarization and causes tachycardia

Question 22

What do calcium channel blockers cause

Answer 22

cause bradycardia by indibiting the slow inward currents

Question 23

What does digitalis cause

Answer 23

causes bradycardia by increasing parasympathetic activity on the Sa node

Question 24

What does sympathetic inn release and what does it bind to

Answer 24

release norepinephrine which B1 adrengenergic receptors

Question 25

What does sympathetic stim do specifically to the heart (2)

Answer 25

1. Increase inward Na current (increase depolarization)

2. open more ca channels (faster upslope)

Question 26

What does parasympathetic inn release and what does it bind to

Answer 26

releases aCh which binds to M2 muscarinic cholinergic receptors

Question 27

what does parasympathetic stim do specificaaly to the heart (3)

Answer 27

1. Decreasing inward Na current (slow depol)
2. Slow opening of ca channels (decrease upstroke speed)
3. Opening more k channels (causes hyperpolarization)