HHD - AJ

Question 1

CO=

Answer 1

HR x SV

Question 2

Muscle contraction

Answer 2

Ca2+ binds to troponin C, causing unmasking of binding sites on actin filaments, allowing myosin heads to bind.

Question 3

Primary pacemaker

Answer 3

Sino-atrial node

Question 4

Sympathetic input

Answer 4

Noradrenaline effects contractility

Question 5

Resting membrane potential of cardiac cell

Answer 5

-80mV

Question 6

ECG

Answer 6

Electrocardiogram - electrical signal that can be measured at the body’s surface.

Question 7

P wave

Answer 7

Atrial depolarisation

Question 8

QRS

Answer 8

Ventricular depolarisation

Question 9

QT

Answer 9

Ventricular depolarisation to repolarisation

Question 10

Voltage difference across mitochondrial membrane

Answer 10

150mV

Question 11

Technique determining what occurs in cardiac muscle

Answer 11

Sucrose-gap voltage clamp - using K-tyrode to represent cytosol.
Tracking to pulse to tracking.
Creates a feedback loop - shows calcium ion influx as a slow inward current.

Question 12

Whole-cell patch clamp recording

Answer 12

Single electrode, electrolyte filled glass micropipette.
Interaction between phospholipid bilayer and the tip creates a seal.
Get current-voltage relations of calcium influx.
Low voltages - no current as channels aren’t open.
Open with stronger depolarisation = voltage gated.

Question 13

Evidence for CICR

Answer 13

Skinned myocytes - permeabilising the membrane. Alterations in calcium concentration bathing the cytosol - look at aequorin which reflects the release of Ca2+ from the SR.

Question 14

Calcium transient

Answer 14

The increase in cytosolic concentration of calcium in the cell that reaches a peak, then recovers to the baseline level.