block 2 lecture 10

Question 1

what is the appearance of cardiac muscle?

Answer 1

striated, branched with intercolated discs

Question 2

what ensures the muscle acts as one functional unit?

Answer 2

wave of depolarisation moves via gap junction

Question 3

what are myocytes made up of?

Answer 3

myofibrils

Question 4

myosin structure?

Answer 4

tail region of alpha chains in an alpha helix
hinge region
2 heads
regulatory light chians 
alkyle light chains

Question 5

what allows myosin heads to bind to the actin?

Answer 5

hydrolysis of ATP

Question 6

what type of protein is actin?

Answer 6

globular

Question 7

what is the structure of actin?

Answer 7

two helical stands

inbetween strands is tropomyosin

Question 8

what is the troponin complex?

Answer 8

troponin I
troponin C
troponin T

Question 9

what is troponin I?

Answer 9

the inhibitory part

Question 10

what does troponin C do?

Answer 10

binds to calcium ions

Question 11

what does troponin T do?

Answer 11

keeps the troponin bound to the actin

Question 12

what happens to troponin when calcium binds?

Answer 12

confirmational change and cross bridges can form

Question 13

what happens to the products of ATP hydrolysis when it binds to myosin?

Answer 13

stays bound

Question 14

what produces the power stroke?

Answer 14

inorganic phosphate is released

Question 15

what is excitatory contraction coupling?

Answer 15

an action potential triggers a myocyte to contract

Question 16

what happens when an action potential depolarises the membrane of a myocyte?

Answer 16

calcium ion channels open allowing influx of calcium ions

Question 17

what are dihydropyridine receptors?

Answer 17

voltage gated calcium ion channels in the T tubules

Question 18

what are ryonidine receptors?

Answer 18

receptor on the sarcosplasmic reticulum

Question 19

what is the calcium release process called in the muscle of the heart?

Answer 19

calcium induced calcium influx

Question 20

what controls the rate and force of contraction?

Answer 20

autonomic nervous system

Question 21

what is released in the sympathetic system and where is it released from?

Answer 21

noradrenaline from the accelerator nerve

adrenal glands secrete adrenaline

Question 22

what happens when the neurotransmitter of the sympathetic nervous system binds to the calcium receptors?

Answer 22

triggers calcium ion channels to trigger an influx of calcium ions which induces calcium release from the sarcoplastic reticulum

Question 23

what can the noradrenaline bind to?

Answer 23

beta 1

Question 24

what happens when noradrenaline binds to beta 1?

Answer 24

activates adenylate cyclase, forms cAMP, protein kinase phosphorylated, phospholamban phosphorylated so sarcoplasmic reticulum can pump calcium in

Question 25

what is lusitropy?

Answer 25

relaxation

Question 26

how does lusitropy work?

Answer 26

sarcoendoplasmic reticulum calcium ATPase returns calcium into the sarcoplasmic reticulum, sodium/calcium exchanges in the sarcolemma transports calcium out of the cell

Question 27

where are the cardiac inhibitory and cardiac accelerator centers?

Answer 27

medulla

Question 28

what does the sympathetic nerve innervate?

Answer 28

nodes and ventricular muscle

Question 29

what does the SAN release and where does it go?

Answer 29

acetylecholine onto the muscarinic receptors

Question 30

what affects does noradrenaline have?

Answer 30

positive chronotropy positive dromotropy positive inotropy

Question 31

what is positive chronotropy?

Answer 31

increase heart rate

Question 32

what is positive dromotropy?

Answer 32

increased conduction velocity

Question 33

what is positive inotropy?

Answer 33

increased contractility

Question 34

what does acetylecholine bind to?

Answer 34

M2 receptors

Question 35

what does acetylecholine binding to M2 receptors do?

Answer 35

negative chronotropy, dromotropy and inotropy

Question 36

what happens when noradrenaline is released from the SAN?

Answer 36

bind to beta 1 coupled to G stimulatory proteins, CAMP is formed and protein kinase A is activated, calcium ion channel is depolarised, this increases action potential generation resulting in increased chronotropy and inotropy

Question 37

what happens exactly when acetylecholine is released from SAN?

Answer 37

binds to muscarinic M2 inhibiting G proteins meaning you get phosphorylation of a potassium ion channel (GIRK) this causes potassium ions to leave the cell, this hyperpolarises the cell and decreases the heart rate

Question 38

phase 4? sino atrial node action potential

Answer 38

sodium influx, calcium ion channels recover from inactivation, pump restores the ion gradient

Question 39

phase 0? sino atrial node action potential

Answer 39

calcium ions influx this depolarised the SAN cells

Question 40

phase 3? sino atrial node action potential

Answer 40

calcium ion channels become inactivated and there is a delayed potassium ion efflux to restore resting potential.

Question 41

important feature of atrial emptying?

Answer 41

mostly passive

Question 42

route of electrical activity in the heart?

Answer 42

sino atrial node bundle of hiss purkinje fibers

Question 43

what is the anulus fibrosus?

Answer 43

acts as an electrical insulator between the atria and ventricles

Question 44

what is the pacemaker of the heart?

Answer 44

SAN

Question 45

what is EDV?

Answer 45

end diastolic volume | volume of blood left at the end of diastole

Question 46

what is isovolumetric contraction?

Answer 46

when volume of blood remains the same but the pressure is increasing due to contraction