Myocyte Contraction Coupling

Question 1

Syncytium meaning

Answer 1

each muscle cell is joined to the next by intercalated disk

Question 2

What are intercalated disks made of

Answer 2

desmosomes and gap junctions

Question 3

What is the function of gap junctions

Answer 3

propagate electrical activity

Question 4

Where do gap junctions exist between

Answer 4

myocytes

Question 5

What are desmosomes

Answer 5

mechanical links

Question 6

What are the structural units of muscle

Answer 6

sarcomeres

Question 7

What filaments form cross bridges in muscle

Answer 7

actin and myosin

Question 8

What does the degree of overlap of contractile proteins determine

Answer 8

strength of contraction

Question 9

Describe the relationship between overlap and strength of contraction

Answer 9

as overlap increases strength of contraction increases

Question 10

Process of what muscles is a calcium dependant process

Answer 10

skeletal and cardiac muscle

Question 11

Describe one unit of sarcomere

Answer 11

region lying between two Z lines

Question 12

What is the importance of the sarcomere unit

Answer 12

determines strength of contraction in myocytes in terms of heart beat

Question 13

What are ryanodine receptors

Answer 13

calcium channels

Question 14

What is the function of ryanodine receptors

Answer 14

calcium induced calcium release

Question 15

What does calcium influx cause in muscle

Answer 15

contraction

Question 16

Where does calcium come from in cardiac cells

Answer 16

extracellular fluid

Question 17

How does calcium enter the cardiac cells from the extracellular fluid

Answer 17

L type calcium channels

Question 18

What is the most important L type calcium channel

Answer 18

Cav1.2

Question 19

Where are ryanodine receptors present

Answer 19

sarcoplasmic reticulum

Question 20

What have a physical mechanical link in cardiac cells

Answer 20

Cav1.2 and ryanodine receptors

Question 21

What do you need for cardiac contraction in terms of channels

Answer 21

both ryanodine receptors and L type channel function

Question 22

Where is SERCA2a found

Answer 22

sarcoplasmic reticulum

Question 23

What type of transporter is SERCA2a

Answer 23

ATPase

Question 24

What is the function of SERCA2a

Answer 24

pump calcium against its conc grad into sarcoplasmic reticulum

Question 25

What is NCX1

Answer 25

sodium calcium exchanger

Question 26

What does NCX1 exchange

Answer 26

sodium in for calcium out

Question 27

What type of transporter is PMCA

Answer 27

ATPase

Question 28

What is the function of PMCA

Answer 28

moves calcium out and hydrogen ions in

Question 29

Where is MiCa located

Answer 29

mitochondrial membrane

Question 30

Describe the driving force for mitochondria and calcium

Answer 30

strong driving force for mitochondria to take up calcium

Question 31

What is an important calcium store in muscle cells

Answer 31

mitochondria

Question 32

What is the potential inside mitochondria

Answer 32

-160mV

Question 33

What does decreased calcium levels cause

Answer 33

cardiac relaxation

Question 34

What does the strength and velocity of contraction depend on

Answer 34

myocyte and muscle

Question 35

What are myocytes

Answer 35

sensitive contractile proteins to Ca2+

Question 36

What is the pre load

Answer 36

end diastolic volume

Question 37

What changes at myocyte level

Answer 37

pre load EDV, and afterload arterial pressure

Question 38

What is the main concept of muscle

Answer 38

passive and active tension

Question 39

Describe passive muscle tension

Answer 39

tension generated at a set sarcomere length without sitmulation

Question 40

Describe active muscle tension

Answer 40

tension generated by stimulation of the muscle at set sarcomere length

Question 41

Definition of isometric

Answer 41

held at a specific length, tension changes

Question 42

Describe the sarcomere when it is bunched up

Answer 42

no cross bridges

Question 43

What is the effect on contraction at shorter sarcomere lengths

Answer 43

strength of contraction not as effective

Question 44

What sarcomere length is specific to cardiac muscle

Answer 44

2.2um

Question 45

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

Answer 45

as length increases the tension increases

Question 46

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

Answer 46

passive

Question 47

Describe the proteins in stretch cardiac muscle

Answer 47

closer

Question 48

What does increased tension in stretch cardiac muscle activate

Answer 48

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

Question 49

What is Starling's law

Answer 49

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

Question 50

What is EDV

Answer 50

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

Question 51

What EDV play a role in

Answer 51

determining strength of contraction

Question 52

What is diastole

Answer 52

passive

Question 53

What is systole

Answer 53

active

Question 54

How can you calculate velocity of shortening

Answer 54

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

Question 55

What happens during the iso-volumetric contraction phase of shortening

Answer 55

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

Question 56

Describe the isotonic phase of contraction

Answer 56

disengage the screw, muscle shortens, lifts weight from table

Question 57

What is a measure of the velocity of shortening

Answer 57

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

Question 58

Describe isotonic contraction

Answer 58

tension remains constant but length of muscle can change

Question 59

What is the relationship between load weight and afterload

Answer 59

when muscle lifts a heavy load the afterload is slower

Question 60

What is the relationship between velocity of shortening and weight

Answer 60

as weight increases, velocity of shortening also increases

Question 61

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

Answer 61

strong and fast contraction

Question 62

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

Answer 62

weaker and fast contraction

Question 63

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

Answer 63

weak and slow contraction

Question 64

What is the relationship between HR and contracted

Answer 64

as HR increases contraction also increase

Question 65

Why does increasing HR increase contraction

Answer 65

increased calcium release from sarcoplasmic reticulum