excitable heart

Question 1

SA node

Answer 1

• unstable phase 4

- automaticity

Question 2

transmembrane conductance

Answer 2

• POTASSIUM

Question 3

UNGATED POTASSIUM CHANNEL

Answer 3

• constant
• concentration dependent
• it is happening all the time

Question 4

VOLTAGE GATED SODIUM CHANNELS

Answer 4

• not constant
• based on electrical charges
• affected by action potential

Question 5

VOLTAGE GATED CALCIUM CHANNELS

Answer 5

• not constant

Question 6

VOLTAGE GATED POTASSIUM CHANNELS

Answer 6

• not constant

Question 7

Na+ permeability

Answer 7

• fast channel

Question 8

Ca2+ permeability

Answer 8

• slow channel

Question 9

K+ permeability

Answer 9

• slow channel

Question 10

membrane potential (Inside the cell)

Answer 10

• 90mV due to potassium going out NORMALLY

- it becomes positive when sodium goes IN

Question 11

Calcium2+ L type channels

Answer 11

• stays plateau positive

- going IN

Question 12

Phase 0

Answer 12

• fast channels open gNa
• depolarization
• opens and close quickly

Question 13

Phase 1

Answer 13

• slight repolarization
• due to transient Potassium current
• closing of the sodium channels

Question 14

arrhythmia

Answer 14

treatment to lower mortality beta blockers not anti arrhythmic drugs because it is also a pro drug

Question 15

Phase 2

Answer 15

• L-type Ca2+ are open
• Calcium influx (maintains the interior +)
• K channels are closed and leaving efflux
• CALCIUM channel antagonist shorten the plateau (NIFEDIPINE, NICARDIPINE, AMLODIPINE ETC) stops the calcium going IN
• POTASSIUM channel antagonist lengthen the plateau (

Question 16

hyperpolarized

Answer 16

• becomes more negative from -70 to -90

Question 17

lethal injection

Answer 17

• sudden depolarization of the heart

- K

Question 18

Phase 3

Answer 18

• L type Ca2+ channel closes gCa
• large K efflux
• cells quickly repolarized

Question 19

Phase 4

Answer 19

• gK high
• voltage gated and unrated potassium channels open
• relative refractory period

Question 20

SA node

Answer 20

• top of the atrium

Question 21

AV node

Answer 21

• bet the atria and ventricle

Question 22

nodal channel

Answer 22

• no phase 1 and 2

Question 23

acetylcholine

Answer 23

• vagal stimulation

Question 24

beta blockers

Answer 24

• blocks the sympathetic stimulation

Question 25

lightheadedness, pulse 40 what is the initial therapy

too slow speed up by

Answer 25

• atropine (anitcholinergic)
• anti vagal stimulation
• anti parasympathetic
• stimulate sympathetic

Question 26

rapid atrial fibrillation initial therapy

too fast slow it down with

Answer 26

• beta blockers to slow down

- stimulate parasympathetic