anatomy of heart and cycle

Question 1

heart wall

Answer 1

endocardium - inner layer lined with endothelial cells
myocardium - muscular layer
epicardium - visceral coats organ, pericardium lines body cavity

Question 2

what does the heart sit in

Answer 2

pericardium
air filled sack
protects and anchors heart to mediastinum

Question 3

issues with pericaridum

Answer 3

cardiac tamponade
can become filled with blood/fluid
compress chambers of heart, prevents complete filling

Question 4

major vessels

Answer 4

right 
superior/inferior vena cava
pulmonary arteries (from trunk)
left
aorta
pulonary vein

Question 5

cardiac cycle

Answer 5

blood enters atria, AV open 
atria contract so all blood out
ratio relax, AV valves shut
ventricles contract, SL open
ventricules relax, back flow of blood closes the SL valves

Question 6

AV valves

Answer 6

bicuspid left
2 envelopes
tricuspid
three envelopes, blood flows more easily as it opens up greater

Question 7

how are the values attached

Answer 7

cordae tendineae anchor valves to papillary muscles

prevent inversion of valves

Question 8

semi lunar valves

Answer 8

cusp shaped

blood fills the cusps and closes them

Question 9

heart sounds

Answer 9

lub dub
av
SL valve
heart murmur if leakage

Question 10

cardiac muscle

Answer 10

short
fat branched
intercalated disks
lots of mitochondria and good blood supply

Question 11

action potentials in conductive cells

Answer 11

no stable resting potential, fires to give heart rhythm
spontaneous depolarisation due to Na cells
influx of ca ions to reach threshold then rapid influx
K then leaves SA node to repolarise

Question 12

action potentials in contractile cells

Answer 12

stable resting potential
influx of Na stimulated by neighbouring cell
Ca channels open, depolarisation
K then opens and repolarised
plateau is refractory period - keeps HR regular

Question 13

ions to kill

Answer 13

potassium chloride
increases extracellular conc of K outside cell
reduced myocardial excitability

Question 14

flow of electrical activity through the heart

Answer 14

SA node signal to AV via condition pathways
slight delay
then bundle of His and purkyne fibres

Question 15

cardiac muscle contraction

Answer 15

AP stimulate Ca influx
induces further release of Ca from stores in sarcoplasm retriculum (smooth ER not in muscles) - calcium induced calcium release
Ca binds to troponin

Question 16

what is realeased once heart attack occurs

Answer 16

cardiac troponins

due to lack of O2 to heart cells so the die and are released into blood