Intro to cardio

Question 1

What is cardio electrophysiology

Answer 1

The study of the electrical activity of the heart

Question 2

what is cardiovascular mechanics?

Answer 2

understanding how the contractile properties of the heart affect its function

Question 3

what is cardiovascular hemodynamcs

Answer 3

the study of blood flow and the factors that control it

Question 4

what type of tissue is blood

Answer 4

connective tissue with a fluid ECM

Question 5

how many pumps does the heart have and where do they pump blood to?

Answer 5

2 pump - the right and left side
- the right side pumps blood to the lungs to be oxygenated and left to the systemic circulation

Question 6

what are the chambers of the heart

Answer 6

4 chambers : right and left atrium and right and left ventricle

Question 7

what are the ventricles separated by and why

Answer 7

they are separated by the interventricular septum to prevent the mixing of blood

Question 8

what are the functions of the heart valves?

Answer 8

to prevent back flow

Question 9

what is the function of the aortic and pulmonary semi lunar valve

Answer 9

to prevent back flow into the ventricles

Question 10

what is the function of the mitral and tricuspid valves

Answer 10

to prevent back flow into the atrium

Question 11

what connects the valves to the heart

Answer 11

papillary muscles and chordae tendinae

Question 12

what percentage of blood is pumped from the right atrium to the left ventricle and aorta

Answer 12

100% of the blood from the right atrium returns to the left ventricle and out through the aorta

Question 13

which organ systems receive the most blood

Answer 13

renal
GI
skeletal muscle

Question 14

what is the normal cardiac output ? what does this mean for venous return

Answer 14

5L/min this means venous return is also 5L/min

Question 15

heart function can be charecterized into which 2 events

Answer 15

electrical and mechanical

Question 16

how is mechanical activity of the heart influenced by the electrical

Answer 16

the mechanical activity of the heart is triggered by the electrical stimulus that is triggered within the heart

Question 17

what is automaticity?
what types of cells make it up automaticity?

Answer 17

• the ability of the heart to spontaneously fire action potentials
• pacemaker cells

Question 18

are pacemaker cells neurons

Answer 18

NO they are modified cardiomyocytes

Question 19

what is excitability/responsivness

Answer 19

the ability of the cardaic cells to respond to electrical activity

Question 20

what does excitability of the heart depend on

Answer 20

depends on the refractory period which is the ability of the heart to relax before it contacts again

Question 21

what is conductivity

Answer 21

the ability of the heart to conduct the action potential from its site of origin to all cardiac cells

Question 22

what does conductivity of the hear depend on

Answer 22

depedns on the heart functioning as a functional syncytium in which it functions as a unit

Question 23

how does the concentration of Na,K,Ca,Cl compare outside the cell than inside the cell

Answer 23

• Na is greater outside than inside
• K is greater inside than outside
• Ca is MUCH greater outside than inside
• Cl is greater outside than inside

Question 24

what is the resting membrane potential of a cardiac cell and what is it determined by

Answer 24

• the restin mem potential is between -60 and -85 mv
• depends on the concentration differences of the ions across the cel membrane and the membrane conductance to reach ion

Question 25

what are the 2 types of cardiac muscle cells that generate different action potentials

Answer 25

contractile cells and pacemaker cells(SA and AV node)

Question 26

what is the restinf membrane potentail of contractile cells and pace maker cells

Answer 26

- contractile = -100mv - pacemaker = -60mv

Question 27

how many phases in a cardiac action potential? hoe is the pacemaker cell different

Answer 27

ther are 5 phases but pacemaker cell is different bc it has 4. ( NO plateu phase)

Question 28

what are the phases of a contractile cell action potential

Answer 28

- phase 4: resting membrane potential- opening of inward rectifying K channels - Phase 0: depol- opening of voltage gated Na channels - Phase 1: transient repol: opening of transient outward K channels - phase 2: plateu phase- balance between K and Ca channels (funny channels) - Phase 3: repol: opening of delayed rectifier K channels

Question 29

what are the phases of the pacemaker cell action potential

Answer 29

phase 4: pacemaker potential- opening of inward rectifying K channels and funny channels phase 0: depol- opening of voltage gated Ca channels phase 3: repol: opening of delayed rectifier K channels

Question 30

what are funny channels what do they allow for?

Answer 30

- chanels that have little selecttivity and allow NA and Ca in and K out - allow for automaticity

Question 31

What are the phases of the functional refecactory period of contractile cells and what is included in each

Answer 31

- Effective refractory period > absolute refractory period > relative refractory period - supranormal phase > also know as the vulnerable phase

Question 32

what is the absolute refectory period

Answer 32

- period in which a stronger than normal stimulus can trigger and AP

Question 33

whar is the relative refractory period

Answer 33

- period in which a stronger than normal stiumuls can trigger an AP but it will have an abnormal shape

Question 34

what is the supranormal phase? why is it also known as the vulnerable phase

Answer 34

a normal stimulus can trigger a normal AP bc the channels are almost all recovered - called vulnerable bc the RMP is slightly higher here than normal so can reach a threshold fast and trigger an AP

Question 35

what does a long refecatory period allow for

Answer 35

allows for the heart to recover relax before contracting again

Question 36

how do the phases of heart contraction have to occur for the heart to function properly

Answer 36

must occur in the same order each time

Question 37

what structure allows for the the cardiomyocytes to function as a functional syncytium

Answer 37

- intercalted disks that contain gap junctions that allow electrical stimuli to travel from depolarized cell to neighboring cell that has not been stiumlated yet

Question 38

what are the pacemmakers of the heart?

Answer 38

SA and AV node and purkinjee fibers

Question 39

how are purkinjee fiber part of the pacemaker>?

Answer 39

if the AV node fails to transmit the signal from the atria to the ventricles the purinjee fibers will take over and transmit the signal

Question 40

what is the normal pace maker of the heart and why

Answer 40

the SA node because it has the most AP's per minute

Question 41

what would happen if SA node function stops and AV node takes over as the pacmaker

Answer 41

the HR would decreases because the AV node has generates fewer APs per minute

Question 42

what is overdrive surpression

Answer 42

allows the fastest pacemaker (SA node) contril the heart rate

Question 43

what system modulates the rate of firing of cardiac action potentials

Answer 43

the autonimic NS

Question 44

how how the sympathetic and Para sympathetic NS affect HR and by what mechanisms

Answer 44

- sympatheitic increases because epinephrinse opens Ca channels - para sympathetic decreases because it induces hyperpolarization of the membrane potential

Question 45

what is the cellular response of sympathetic stimulation of the heart

Answer 45

- NE /E released - bind to B1/Gs receptors - Camp increases = increase opening of Ca channels - increases in Na and Ca influx - increase depol - increase HR

Question 46

what is the cellular response of the Parasympathetic NS on the heart

Answer 46

- Ach relaeased - bind to M2/Gi receptor - Camp decreases - increase in K efflux and decreasein Ca influx - decrease rate of depol - decrease HR