Cardio Lec 4

Question 1

Normal heart sounds

Answer 1

s1, s2

Question 2

s1 due to

Answer 2

av valve closing (ventricular systole)

Question 3

s2 due to

Answer 3

semilunar valve closing (ventricular diastole)

Question 4

Heart murmurs

Answer 4

abnormal heart sounds; most often when valve isn’t closing properly so blood is regurgitating due to back flow

Question 5

When would you hear the murmur

Answer 5

when valve should be closed

Question 6

During which phase would a murmur due to mitral valve regurgitation be heard most clearly?

Answer 6

during ventricular contraction

Question 7

Incompetent valves refers to

Answer 7

improper closure (heard as a murmur)

Question 8

Incompetent valves is due to

Answer 8

damage to papillary muscles or chordae tend.

Question 9

Does cardiac muscle beats w/o help on NS?

Answer 9

yes

Question 10

2 types of cells in myocardium

Answer 10

nodal cells & contractile cells

Question 11

Nodal cells aka

Answer 11

pacemaker cells

Question 12

T/F Nodal cells have unstable resting membrane potentials

Answer 12

T (have to fire spontaneously/don’t rely on a signal)

Question 13

What allows heart to beat on own & how

Answer 13

pacemaker cells; nodal cells spontaneously depolarize –> fire an action potential –> send wave to contractile cells –> cause them to depolarize to threshold –> get them to fire action potentials –> heart muscle shortens & contracts

Question 14

Myocardium connected via

Answer 14

gap junctions

Question 15

How does wave spread thru heart as a SINGLE UNIT

Answer 15

by all cells being coupled to one another

Question 16

Atria & ventricles separated via

Answer 16

fibrous skeleton that insulates electrical activity

Question 17

Impulse that starts cycle originates in the

Answer 17

atria near SVC thru SA node aka pacemaker

Question 18

Why is the SA node the pacemaker?

Answer 18

bc it fires more frequently than other areas

Question 19

Do nodal cells contract?

Answer 19

no; they send electrical impulses to contractile cells

Question 20

T/F: Nodal cells depolarize RAPIDLY on their own

Answer 20

F; SLOWLY

Question 21

Pacemaker potential refers to

Answer 21

rate of rise to threshold

Question 22

Funny current/Na channel opens when ___; other ion channels open when ___

Answer 22

membrane potential is most negative; most positive

Question 23

Describe the action potential prod. by nodal cells/ pacemaker

Answer 23

(before threshold) Na channel opens @ -60 (its most negative) -> some depolarization -> causes transient Ca channel to open -> allows Ca & Na to enter -> 2 channels stay open until threshold -> @ threshold, voltage gated Ca channels open -> other 2 channels shut off -> membrane potential RAPIDLY depolarized -> @ peak, all (+) channels close -> K channels open -> cell repolarizes back to -60 -> funny current opens (little depolarization) -> causes t-type Ca channel open -> the 2 depolarize cell to threshold -> cause voltage gated Ca channels to open -> depolarize to peak -> all shut -> K channels open -> start over & over

Question 24

What dictates the HR?

Answer 24

rate/ how FREQUENTLY action potentials occur

Question 25

What would happen if you have a drug that causes channels not to open as fully?

Answer 25

take longer to depolarize --> hr slow down

Question 26

When the cell is firing its action potential that wave of depolarization spreads to

Answer 26

the adjacent cells via gap junctions

Question 27

What causes the myocytes to depolarize to threshold?

Answer 27

the spread to the adjacent cells via gap junctions

Question 28

Pacemaker potential/rise to threshold aka

Answer 28

phase 4

Question 29

Anything that increases slope of phase 4 will

Answer 29

increase hr

Question 30

Anything that decreases slope of phase 4 will

Answer 30

decrease hr

Question 31

Substances that increase slope of phase 4

Answer 31

Epi, norepi (bind to beta1 rs & make it QUICKER to get to threshold)

Question 32

Substance that decrease slope of phase 4

Answer 32

ACH (makes it take LONGER to get to threshold)

Question 33

How do substances binding to beta1 rs increase hr?

Answer 33

increase prod. of cAMP which causes Ca channels & funny current to open -> depolarize faster by bringing more + ions in

Question 34

How does Ach decrease hr?

Answer 34

closes na & ca channels, opens k channels

Question 35

If Ach given in a high enough does it will

Answer 35

stop the heart as a result of closing of channels

Question 36

Which would be expected to result in a reduction in hr?

Answer 36

opening of k channels

Question 37

In pacemaker cells, what ion channels open most dramatically once threshold voltage is reached?

Answer 37

calcium channels

Question 38

Ectopic foci/pacemaker refers to

Answer 38

any area other than SA node that is pacing the heart

Question 39

T/F: The SA node is the only nodal area w/ ability to spontaneously depolarize on its own

Answer 39

F; all nodal areas have the ability BUT DO SO LESS FREQUENTLY

Question 40

T/F: If SA node isn't working properly, AV node can take over & pace the heart

Answer 40

T but hr would be slower (50-60bpm)

Question 41

If AV node blocked

Answer 41

Perkinje fibers can take over & pace ventricles but firing rate rlly infrequent; person would have hr: 30bpm -> person needs pacemaker

Question 42

If area other than SA node or any nodal area is pacing the heart, hr would be

Answer 42

higher

Question 43

What is required for muscle shortening/contraction?

Answer 43

calcium

Question 44

Myocardial action potentials initiated by

Answer 44

impulses from pacemaker cells

Question 45

Ventricular myocyte action potential

Answer 45

cell at RMP (-90 mv) -> depolarization coming from nodal/pacemaker cells -> myocytes to threshold causes na channel to open -> na rushes in & RAPID depolarization -> na channels shut at peak -> k (out) & ca channels open (ca in) -> plateau phase -> ca channels shut -> k channels stay open -> cell re-polarizes

Question 46

Cannot get contraction until __ because

Answer 46

plateau phase bc ca must be present

Question 47

When myocytes fire action potentials it causes

Answer 47

myocytes to contract based on ca coming in

Question 48

Arrythmias/Disrrythmias

Answer 48

abnormal rhythms

Question 49

What do Na, beta, K, & Ca channel blockers do

Answer 49

slow hr

Question 50

Cardiac conduction system

Answer 50

SA node signals atria to contract -> signal to AV node (slowly to allow ventricles to fill) -> thru bundle of his -> down bundle branches -> to perkinje fibers (quickly) -> cause ventricles to contract

Question 51

Cardiac conduction system seen thru

Answer 51

ekg

Question 52

Only way for signal to get from atria -> ventricle is thru

Answer 52

av node

Question 53

Excitation contraction coupling refers to

Answer 53

how the myocyte action potential is coupled to the actual contraction of the myocyte

Question 54

What causes the SR to release its calcium

Answer 54

calcium coming in when the action potential fires in the ventricular myocytes & voltage gated channels open (calcium induced calcium release)

Question 55

Initial calcium comes from

Answer 55

extracellular sources via VGCCs during plateau phase

Question 56

Extracellular calcium triggers

Answer 56

release of further intracellular calcium from SR -> causes contraction