Muscle excitation Flashcards
what are the characteristics of a skeletal muscle?
-long cylindrical cells
-many nuclei per cell
-stirated
-voluntary
-rapid contractions
what are the characteristics of cardiac muscle?
-branching cells
-one or two nuclei per cell
-stirated
-involuntary
-medium speed contractions
what are the characteristics of Smooth muscle?
-fusiform cells
-one nucleus per cell
-nonstirated
-involuntary
-slow wave like contractions
how is the body in electrical disequilibrium but technically electrically neutral?
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
what is an insulator?
prevents the movement of separate charges, the cell membrane works as an insulator
is the cell membrane an insulator or conductor?
insulator
what is the resting membrane potential?
electrical gradient across the cell membrane.the membrane potential has reached a steady state and is not changing
what is the potential?
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.
what is the difference?
the difference in the electrical charge inside and outside the cell
how can we measure the resting membrane potential?
the voltmeter
what does the voltmeter do?
measures the difference in electrical charge between two points (the potential difference) measured in millivolts
what is the equilibrium potential? E
the membrane potential at which the electrical gradient opposes the chemical gradient
how do K ions contribute to resting membrane potential?
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
what is the equilibrium potential for Na+?
+60 mV
what is muscle tonus?
the tightness of a muscle, some fibres are always contracted
what is tetany?
the sustained contraction of a muscle, result of a rapid succession of nerve impulses
what is a refractory period?
brief period of time in which muscle cells will not respond to a stimulus. cardiac muscles have a greater refraction period
what is the resting membrane potential in nerves and muscle?
-40 to -90
which is more negative, the inside or outside of the cell?
inside
what does depolarised mean?
when membrane potential becomes more positive than it is at he resting potential
what does hyper polarised mean?
if membrane potential becomes more negative than it is at resting potential
what does polarised mean?
potential different across a cell membrane
what types of ions are found in neurons?
Na+, Cl- (higher conc outside cell)
K+ (higher conc inside cell)
what is the equilibrium potential for K+?
-90 mV
what is the resting membrane potential of glial cells?
-90 mV, same equal to equilibrium potential of K+
what happens when calcium binds with troponin?
moves tropomyosin and expose the binding sites
what happens when ACh binds to receptors in muscle membrane?
channel opens, permeable to sodium ions, causes sodium to move into muscle cell
what is the motor unit ratio like in back muscles?
1:100
what is the motor unit ratio like in finger muscles?
1:10
what is the motor unit ratio. like in eye muscles?
1:1
why do eye muscles have 1:1 ratio?
precise control needed in vision
what is muscle tonus?
refers to tightness of muscles. in a muscle some fibres are always contracted to add tension or tone eg posture
what is tetany?
sustained contraction of a muscle
result of rapid succession of nerve impulses
