anatomy Flashcards
neurotransmitters
the chemical messages past between two neurons at a synapse
action potential
the electrical messages that tells the presynaptic cell to release chemical messages
resting membrane potential
the membrane potential of an unstimulated resting cell
graded membrane potential
a temporary localized change in RMP
Action potential
an electrical impulse that is spread along the surface of an axon occurs when GP is sufficiently large
the resting membrane potential of most neurons is
-70 mv
how does a cell use active forces to maintain resting membrane potential?
sodium-potassium exchange pump where 2K+ goes in the cell and 3Na+ goes out
what would happen if the cell body wasn’t able to maintain resting membrane potential?
no action potential would be generating. No intercellular communication involving nervous system
gated channels (chemically gated)
open when NT bond
gated channels (voltage gated)
open at pre-set
gated channels
stay closed until they get the signal to open (action potential)
during depolarization chemically gated ion channels are
open
what happens during depolarization
Na+ ions enter the cell causing membrane potential to become less negative
the chemical stimulus that was applied to the cell in the first half was an
excitatory neurotransmitter
the chemical stimulus that was applied to the cell in the second half of the graded potential graph was
an inhibitory neurotransmitter
if a graded potential is strong enough for the membrane potential to reach threshold(-55mv) what could occur?
an action potential
look at the graph these are the steps
1: at the resting state theres an sodium/potassium exchange pump: 3 Na+ out/ 2K+ in NO CHANNELS OPEN
2: at the repolarization sodium voltage channels open allowing Na+ to enter cell until K+ channels are closed
3: at the repolarization, potassium channels open allowing K+ to leave. Na+ channels close
4: undershoot refractory period K+ channels close. Na+ channels closed
resting potential
the K+ is in the cell and the Na+ is around it making a -70mV
refractory period
the Na+ is in the cell and the K+ is outside the cell making it -90mV
what determines the action potential speed?
- diameter of the axon
-myelination of axon
excitatory neurotransmitters
acetylcholine
norepinepherine
glutamate
dopamine
inhibitory neurotransmitters
serotonin
GABA
dopamine
steps of intercellular communication pt.1
- a sensory receptor is depolarized by an arriving enviornmental stimulus
- an action potential is generated by the sensory neuron
- the action potential of the sensory neuron arrives at the sensory neurons axon terminal
- the depolarization of the sensory neurons axon terminal opens calcium channels
- an excitatory neurotransmitter is released from the axon terminal of the sensory neuron
- the excitatory neurotransmitter binds to the post synaptic membrane of the interneuron
- chemically gated sodium channels open the interneurons dendrites
steps of intercellular communication pt.2
- a graded potential change occurs on the interneuron
- summation occurs at the axon hillock of the interneuron
- voltage-gated sodium channels open at the axon hillock of the interneuron
- an action potential is generated and spreads down the axon of the interneuron
- the membrane potential pf the interneurons axon reaches +30mV
- potassium channels open on the interneuron
- the sodium-potassium exchange pump restores resting membrane potential
what are the three muscle types
skeletal, cardiac, and smooth
which type of muscle can be voluntarily controlled
skeletal
thin filaments are composed of
actin
thick filaments are composed of
myosin
the H-zone contains only
thick filaments
the I band contains only
thin filaments
the A band contains
both thick and thin filaments
where is calcium stored
the sarcoplasmic reticulum of the muscle
when it reaches the muscle calcium will bind to
troponin
the binding of calcium and troponin allows
myosin heads to bind to actin
during a muscle contraction does the sarcomere shorten or lengthen
thin(actin) filaments slide over thick(myosin) filaments, the Z line get closer together and the I band gets shorter. The H band gets narrower
what happens during a muscle contraction?
A motor neuron releases the neurotransmitter acetylcholine onto the muscle, which is an excitatory neurotransmitter because it depolarizes the muscle membrane
what does the motor signal cause
the release of calcium ions from the sarcoplasmic reticulum
steps of a muscle contraction
- an action potential arrives from the motor neuron at the motor plate of a skeletal muscle
- Acetylcholine is released from the motor neuron and bound by the motor neuron and bound by the motor end plate of the muscle
- the binding of Acetylcholine excites the membrane of the post synaptic cell which causes the release of Ca+2 from the sarcoplasmic reticulum
- calcium interacts with troponin allowing myosin heads to bind to actin filament
- Thick and thin filaments of the sarcomere interact by sliding. the thin filaments slide towards M-Line, shortening sarcomere
- The H bands and I bands narrow, the A band stays the same width
- z lines move closer together
the tension produced by an individual muscle fiber varies depending on
resting sarcomere length
frequency of stimulation
the overall tension produced by an entire skeletal muscle is determined by
- amount of tension generated by each fiber in muscle
- # of fibers
muscle contraction order:
1: A sensory neuron is activated and sends a sensory signal to the CNS for processing
2: an interneuron tells a motor neuron to fire an action potential
3: Acetlycholine is released from the axon terminal of the motor neuron
4: opening of chemically gated sodium channels causes depolarization of the plasma membrane of a muscle fiber
5: calcium is released from the sarcoplasmic reticulum
- calcium binds to troponin
7: tropomyosin is displaced exposing myosin head binding sites on actin filaments
8: myosin heads bind to actin filaments
9: myosin heads pull actin filaments towards M line of sarcomere (power struggle)
10: the sarcomere shortens and the muscle contracts
know structure of sarcomere
look on paper
know structure and label muscle
look on paper
visceral sensory receptors(afferent)
monitor internal organs
somatic sensory receptors (afferent)
monitor skeletal muscles, joints, and skin surface
special sensory receptors (afferent)
monitor smell, taste, vision, balance, and hearing
efferent division
somatic, autonomic
autonomic has
parasympathetic and sympathetic
somatic has
skeletal muscle
afferent
sensroy stimuli come into the cNS
efferent
motor commands
interneurons
located between sensory and motor neurons.
their job is to distribute sensory information and coordinate motor activity.
cell body
contains nucleus and perikaryon
- Perikaryon contains organelles to make ATP and neurotransmitters
Dendrites
receive information from other neurons
axons
may be myelinated (covered with a protective coating) or unmyelinated (exposed to interstitial fluid)
telodendria
branch off of axon to form axon terminals
axon terminals meet with another cell to form a synapse
presynaptic cell (synapses)
sends messages
postsynaptic cell (synapses)
receive message
presynaptic cells release neurotransmitters into synaptic cleft by
exocytosis of vesicles
Postsynaptic cell contains receptors on membrane to bind neurotransmitters from
synaptic cleft
how to maintain homeostasis in cells
restricting what can go in and out of cell by selectively permeable cell
cells have an ion pump
move around ions as needed to maintain membrane potentials
