heart shit

Question 1

Basics of ions and contractility

Answer 1

Na enters to depolarize and spread current
during plateau, Ca enters while K exits
Ca entry triggers myocardial contraction
K exits to repolarize cell
RMP maintained by K conductance and pumps

Question 2

RMP: what is the voltage?

Answer 2

negative 80-90mV

Question 3

Phases of depolarization (the numbered ones)

Answer 3

phase 0- depolarization (rapid), fast Na channels
phase 1- brief, small repolarization
phase 2-plateau
phase 3-big repolarization (open K channels)
phase 4- resting (RMP)

Question 4

conductance is changed or regulated by:

Answer 4

trans-membrane voltage
time after opening
extracell ion concentrations
ligands binding the receptors

Question 5

RMP: conductance to ions at rest?

Answer 5

K- high
Na- low
proteins- low

Question 6

What are effects of digitalis?

Answer 6

Blocks Na/K ATPase, which helps the cell repolarize
so- it controls irregular heart rates by slowing signals that start in the SA node and therefore reducing AV impulses
also - increases amount of calcium in cells thereby increasing contractility

Question 7

:clinical points of Na channels-

Answer 7

hyperkalemia inactivates Na channels

Question 8

Vaughan Willilams classes and examples

Answer 8

class 1 Block Na channels: lidocaine, procainamide, qunidine
class 2 Beta blockers- atenolol and LOLs
blocking B decreases Ca influx and Ca effects in heart
class 3 block K channels: amiodarone and sotalol (also B blocker), prolong repolarization and ERP
class 4 block calcium channels: dilitiazem and amlodipine

Question 9

treating rhythm disturbances?

Answer 9

Vaughan-will class 1, usually lidocaine

Question 10

phase zero in pacemaker cells uses….

Answer 10

calcium ions for phase 0 depolarization
transient open first, very fast
long lasting open at less negative MP and we can manipulate these with drugs

Question 11

Parasympathetic system and K channels…..

Answer 11

Ach from vagus nerve OPENS K channel, which slows DEpolarization but speeds up REpolarization, moreso in atria than ventricles

Question 12

the only two parts that dont use Na for phase 0 depolarization

Answer 12

SA node and AV node

purkinjes are Na dependent!

Question 13

effects of Autonomic system on SA and AV nodes

Answer 13

sympathetic- speeds the spontaneous depolarization and increases HR and AV conduction
parasymp- decreases both of those (vagus)

Question 14

hyperkalemia effects on ECG

Answer 14

no P wave, big tented T wave, abnormal ST-T

slow HR

Question 15

left sided failure causes…..

Answer 15

pulmonary edema

Question 16

right sided failure causes….

Answer 16

elevated systemic venous pressure, jugular distention, subq edema, and ascites

Question 17

pleural effusion could be caused by

Answer 17

right, left, or especially biventricular failure