cardiac muscle

Question 1

Describe the structure of the heart

Answer 1

left atrium
left ventricle

right atrium
right ventrical

aorta

Question 2

what are the heart cells termed as

Answer 2

Ventricular muscle cells

Question 3

What structures are located at the intercalated disc

Answer 3

desmosomes

gap junctions

Question 4

describe the feature of desmosomes

Answer 4

prevents separation of cardiac muscle during contraction

Question 5

describe the function of gap junctions

Answer 5

allows action potenital to be carried from one cell to the next

Question 6

what to desmosomes and gap junctions allow the heart to do

Answer 6

allows coordination

Question 7

Describe action potential within the heart

Answer 7

long

has a plateau phase as there is a presence of Ca

membrane potential depolarized throughout most of the twitch phase

Question 8

Does summation/ tetanus occur within the ventricular myocute

Answer 8

No

unlikely

Question 9

what are the three major phases of the Action potential in cardiac muscle cells

Answer 9

0. Rapid depolarisation
1. Plateau
2. Repolarisation

Question 10

Rapid depolarization

Answer 10

Fast opening of voltage gated NA channels

Question 11

Plateau

Answer 11

Slow voltage voltage gated Ca channel

Question 12

Depolarisation

Answer 12

Closing of Ca channels opening of K channels (influx of K outward)

Question 13

What does the Ca influx cause

Answer 13

triggers the opening of Ca sensitive channels in the SR= burst of Ca

CALCIUM INDUCED CALCIUM RELEASE

Question 14

What does Calcium cause the Cardiac muscle to do

Answer 14

CONTRACTION

Question 15

What controls and regulates the Ca2+ back into the SR for a ventricular myocute

Answer 15

Na+/Ca+ exchanger

Ca2+ ATPase active pump

Question 16

State the equation for cardiac regulation

Answer 16

CO= SV x HR

Question 17

who is HR set by

Answer 17

set by the pacemaker in the sinoatrial node

Question 18

Who affects the HR

Answer 18

Autonomic nerves releasing neurotransmitters

Question 19

Describe the SA + AV node potential

Answer 19

unstable membrane potential

Depolarisation due to relatively slow Ca2+ current

Question 20

Vagus nerve

Answer 20

Parasympathetic
decreases HR releases Ach

slows down depolarisation & hyperpolarises the resting membrane potential

Question 21

Sympathetic cardiac nerve

Answer 21

increases heart rate
and force of contraction
releases noradrenaline

increases rate of depolarisation

Question 22

what is stroke volume

Answer 22

tension developed by the cardiac muscle fibres

Question 23

what increases stroke volume

Answer 23

increased HR

increases stretch of the ventricles

neurotransmitters (noradrenaline)

Question 24

Increasing Heart rate causes what to stroke volume

Answer 24

increases stroke volume as their is less time for Ca2+ to be released from the cell

Question 25

Describe the length tension relationship within ventricular myocyte

Answer 25

• increased stretch
  = increase volume
  = increase contraction

Question 26

What does increased noradrenaline cause

Answer 26

leads to increased cytosol calcium

therefore there in increased output

increased inotropy and heart rate