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BMS 242 CVS & Respiration > Myocyte Contraction Coupling > Flashcards

Myocyte Contraction Coupling Flashcards

1
Q

Syncytium meaning

A

each muscle cell is joined to the next by intercalated disk

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2
Q

What are intercalated disks made of

A

desmosomes and gap junctions

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3
Q

What is the function of gap junctions

A

propagate electrical activity

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4
Q

Where do gap junctions exist between

A

myocytes

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5
Q

What are desmosomes

A

mechanical links

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6
Q

What are the structural units of muscle

A

sarcomeres

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7
Q

What filaments form cross bridges in muscle

A

actin and myosin

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8
Q

What does the degree of overlap of contractile proteins determine

A

strength of contraction

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9
Q

Describe the relationship between overlap and strength of contraction

A

as overlap increases strength of contraction increases

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10
Q

Process of what muscles is a calcium dependant process

A

skeletal and cardiac muscle

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11
Q

Describe one unit of sarcomere

A

region lying between two Z lines

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12
Q

What is the importance of the sarcomere unit

A

determines strength of contraction in myocytes in terms of heart beat

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13
Q

What are ryanodine receptors

A

calcium channels

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14
Q

What is the function of ryanodine receptors

A

calcium induced calcium release

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15
Q

What does calcium influx cause in muscle

A

contraction

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16
Q

Where does calcium come from in cardiac cells

A

extracellular fluid

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17
Q

How does calcium enter the cardiac cells from the extracellular fluid

A

L type calcium channels

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18
Q

What is the most important L type calcium channel

A

Cav1.2

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19
Q

Where are ryanodine receptors present

A

sarcoplasmic reticulum

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20
Q

What have a physical mechanical link in cardiac cells

A

Cav1.2 and ryanodine receptors

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21
Q

What do you need for cardiac contraction in terms of channels

A

both ryanodine receptors and L type channel function

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22
Q

Where is SERCA2a found

A

sarcoplasmic reticulum

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23
Q

What type of transporter is SERCA2a

A

ATPase

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24
Q

What is the function of SERCA2a

A

pump calcium against its conc grad into sarcoplasmic reticulum

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25
Q

What is NCX1

A

sodium calcium exchanger

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26
Q

What does NCX1 exchange

A

sodium in for calcium out

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27
Q

What type of transporter is PMCA

A

ATPase

28
Q

What is the function of PMCA

A

moves calcium out and hydrogen ions in

29
Q

Where is MiCa located

A

mitochondrial membrane

30
Q

Describe the driving force for mitochondria and calcium

A

strong driving force for mitochondria to take up calcium

31
Q

What is an important calcium store in muscle cells

A

mitochondria

32
Q

What is the potential inside mitochondria

A

-160mV

33
Q

What does decreased calcium levels cause

A

cardiac relaxation

34
Q

What does the strength and velocity of contraction depend on

A

myocyte and muscle

35
Q

What are myocytes

A

sensitive contractile proteins to Ca2+

36
Q

What is the pre load

A

end diastolic volume

37
Q

What changes at myocyte level

A

pre load EDV, and afterload arterial pressure

38
Q

What is the main concept of muscle

A

passive and active tension

39
Q

Describe passive muscle tension

A

tension generated at a set sarcomere length without sitmulation

40
Q

Describe active muscle tension

A

tension generated by stimulation of the muscle at set sarcomere length

41
Q

Definition of isometric

A

held at a specific length, tension changes

42
Q

Describe the sarcomere when it is bunched up

A

no cross bridges

43
Q

What is the effect on contraction at shorter sarcomere lengths

A

strength of contraction not as effective

44
Q

What sarcomere length is specific to cardiac muscle

A

2.2um

45
Q

Describe increasing sarcomere length on tension in cardiac muscle (passive)

A

as length increases the tension increases

46
Q

What type of tension in cardiac muscle increases with more sarcomere protein overlap

A

passive

47
Q

Describe the proteins in stretch cardiac muscle

A

closer

48
Q

What does increased tension in stretch cardiac muscle activate

A

stretch activated Ca2+ channels - more Ca2+ entry from ECF

49
Q

What is Starling’s law

A

mechanical energy set free on passage from resting to contracted state depends on length of fibres

50
Q

What is EDV

A

end volume in the ventricles at the end of a filling phase

51
Q

What EDV play a role in

A

determining strength of contraction

52
Q

What is diastole

A

passive

53
Q

What is systole

A

active

54
Q

How can you calculate velocity of shortening

A

tension transducer, measure iso-volumetric contraction phase and ejection phase

55
Q

What happens during the iso-volumetric contraction phase of shortening

A

muscle is set to fixed length, muscle is stimulated, tension increases

56
Q

Describe the isotonic phase of contraction

A

disengage the screw, muscle shortens, lifts weight from table

57
Q

What is a measure of the velocity of shortening

A

the speed at which the muscle lifts the weight from the table

58
Q

Describe isotonic contraction

A

tension remains constant but length of muscle can change

59
Q

What is the relationship between load weight and afterload

A

when muscle lifts a heavy load the afterload is slower

60
Q

What is the relationship between velocity of shortening and weight

A

as weight increases, velocity of shortening also increases

61
Q

If there is a large volume and low arterial pressure describe the contraction

A

strong and fast contraction

62
Q

If there is a low volume and low arterial pressure describe the contraction

A

weaker and fast contraction

63
Q

If there is low volume and high arterial pressure describe the contraction

A

weak and slow contraction

64
Q

What is the relationship between HR and contracted

A

as HR increases contraction also increase

65
Q

Why does increasing HR increase contraction

A

increased calcium release from sarcoplasmic reticulum

BMS 242 CVS & Respiration (10 decks)

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