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Flashcards in Normal Structure And function Deck (305)
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1

Cardiac muscle is unstriated - TRUE OR FALSE

False - it is striated

2

Cardiac myocytes are electrically coupled by...

Gap junctions

3

Desmosomes have what function within cardiac muscle?

Provide mechanical adhesion between adjacent cardiac cells

4

Contractile unit of muscle

Myofibril

5

Actin filaments form the light/dark appearance of myofibrils?

Light

6

Within each myofibril, actin and myosin are arranged into....

Sarcomeres

7

Muscle tension is produced by ___ of actin filaments over myosin filaments

Sliding

8

Force generation depends upon ________ interaction between myosin and actin filaments

ATP-dependent

9

Requirements for muscle contraction (2)

ATP
Calcium

10

Role of calcium in muscle contraction

Binds to troponin, moving the tropomyosin away from the actin myosin binding site

11

Calcium is released from the _______ _______ in cardiac muscle

Sarcoplasmic reticulum

12

TRUE OR FALSE - the release of calcium from the sarcoplasmic reticulum is dependent on the presence of extra cellular calcium

True

13

Calcium induced calcium release is

The release of calcium in response to the release of calcium

14

Where does the CIcR start in cardiac muscle?

The calcium influx during ventricular muscle action potential through L-type calcium channels - travels down T-tubules increasing the release from SR

15

Channel that removes calcium from the cell back to the SR

Ca-ATPase

16

Excitation of the heart normally originations in the ________ cells of the ___ ____ ____

pacemaker cells of the SAN

17

The heart is normally under the control of the ___

SAN

18

TRUE or FALSE - the cells in the SAN have a resting membrane potential

False
The SAN constantly drifts towards depolarisation

19

The pacemaker potential is due to what 3 ion currents?

Na influx and K influx (funny current)
Transient Ca influx
Decreased K efflux

20

Ion channel responsible for the rising phase of the action potential in the SAN?

LTCC

21

Ion channel responsible for the falling phase of the action potential in the SAN?

K channel --> K efflux
LTCC inactivation

22

Why is conduction is delayed within the AVN?

to allow for atrial systole

23

Phase 0 of ventricular AP

Na influx

24

Phase 1 of ventricular AP

closure of Na, transient K efflux

25

Phase 2 of ventricular AP

LTCC balanced with transient K efflux

26

Phase 3 of ventricular AP

Ca channels close but delayed rectifier K channels remain open

27

Phase 4 of ventricular AP

resting membrane potential

28

Nerve which exerts continuous control over the heart?

Vagus nerve

29

Autonomic predominant control over the heart?

Parasympathetic

30

Ach from parasympathetic system acts on which receptor in the heart?

M2 muscarinic