Muscle excitation

Question 1

what are the characteristics of a skeletal muscle?

Answer 1

-long cylindrical cells
-many nuclei per cell
-stirated
-voluntary
-rapid contractions

Question 2

what are the characteristics of cardiac muscle?

Answer 2

-branching cells
-one or two nuclei per cell
-stirated
-involuntary
-medium speed contractions

Question 3

what are the characteristics of Smooth muscle?

Answer 3

-fusiform cells
-one nucleus per cell
-nonstirated
-involuntary
-slow wave like contractions

Question 4

how is the body in electrical disequilibrium but technically electrically neutral?

Answer 4

active transport of ions across cell membrane creates an electrical gradient but cells have negative ions on the inside and their matching positive ions are found on the outside

Question 5

what is an insulator?

Answer 5

prevents the movement of separate charges, the cell membrane works as an insulator

Question 6

is the cell membrane an insulator or conductor?

Answer 6

insulator

Question 7

what is the resting membrane potential?

Answer 7

electrical gradient across the cell membrane.the membrane potential has reached a steady state and is not changing

Question 8

what is the potential?

Answer 8

the electrical gradient created by the active transport of ions in a source of stored or potential energy. when oppositely charged molecules come back together again they release energy which can be used to do work.

Question 9

what is the difference?

Answer 9

the difference in the electrical charge inside and outside the cell

Question 10

how can we measure the resting membrane potential?

Answer 10

the voltmeter

Question 11

what does the voltmeter do?

Answer 11

measures the difference in electrical charge between two points (the potential difference) measured in millivolts

Question 12

what is the equilibrium potential? E

Answer 12

the membrane potential at which the electrical gradient opposes the chemical gradient

Question 12

how do K ions contribute to resting membrane potential?

Answer 12

membrane is more permeable to K ions and it leaks out the cell down conc gradient. excess -ve charge builds up inside cell , gradient is formed. the -ve charge attracts K back into the cell down electrical gradient. net movement of K stops

Question 13

what is the equilibrium potential for Na+?

Answer 13

+60 mV

Question 14

what is muscle tonus?

Answer 14

the tightness of a muscle, some fibres are always contracted

Question 15

what is tetany?

Answer 15

the sustained contraction of a muscle, result of a rapid succession of nerve impulses

Question 16

what is a refractory period?

Answer 16

brief period of time in which muscle cells will not respond to a stimulus. cardiac muscles have a greater refraction period

Question 17

what is the resting membrane potential in nerves and muscle?

Answer 17

-40 to -90

Question 18

which is more negative, the inside or outside of the cell?

Answer 18

inside

Question 19

what does depolarised mean?

Answer 19

when membrane potential becomes more positive than it is at he resting potential

Question 20

what does hyper polarised mean?

Answer 20

if membrane potential becomes more negative than it is at resting potential

Question 21

what does polarised mean?

Answer 21

potential different across a cell membrane

Question 22

what types of ions are found in neurons?

Answer 22

Na+, Cl- (higher conc outside cell)
K+ (higher conc inside cell)

Question 23

what is the equilibrium potential for K+?

Answer 23

-90 mV

Question 24

what is the resting membrane potential of glial cells?

Answer 24

-90 mV, same equal to equilibrium potential of K+

Question 25

what happens when calcium binds with troponin?

Answer 25

moves tropomyosin and expose the binding sites

Question 26

what happens when ACh binds to receptors in muscle membrane?

Answer 26

channel opens, permeable to sodium ions, causes sodium to move into muscle cell

Question 27

what is the motor unit ratio like in back muscles?

Answer 27

1:100

Question 28

what is the motor unit ratio like in finger muscles?

Answer 28

1:10

Question 29

what is the motor unit ratio. like in eye muscles?

Answer 29

1:1

Question 30

why do eye muscles have 1:1 ratio?

Answer 30

precise control needed in vision

Question 31

what is muscle tonus?

Answer 31

refers to tightness of muscles. in a muscle some fibres are always contracted to add tension or tone eg posture

Question 32

what is tetany?

Answer 32

sustained contraction of a muscle
result of rapid succession of nerve impulses