PNB 2774 Exam 2

Standard Membrane Potential

-70mV

active neuron behavior

things happening in neuron, channels opening and closing

passive neuron behavior

membrane acting as a wire, no further activity

High

relative resting concentration of potassium inside cell

low

relative resting concentration of potassium outside of the cell

Low

relative resting concentration of sodium inside the cell

high

relative resting concentration of sodium outside the cell

low

relative resting concentration of chloride inside cell

high

relative resting concentration of chloride outside cell

potassium ions

the membrane is always permeable to these, mostly through leaky channels at rest

Nernst Potential of Na+

+61mV

Nernst Potential of K+

-93mV

Nernst Potential of Cl-

-75mV

fast, slow, depolarization, positive

Na+ Voltage Channels activate and deactivate _______, and inactivate and unblock ______, they are opened during __________, and act as a ________ feedback loop

slow, depolarization

K+ Voltage Channels activate and deactivate ________, they do not inactivate/unblock, they are opened during _______

upstroke

part of action potential in which sodium influx dominates

downstroke

part of action potential in which potassium efflux dominates

steady state

unchanging state only maintained through constant input and output

little

calcium can flow, but contributes ______ to membrane potential

subthreshold, passive, electrotonic, degrade, action potential, variable, depolarizing, hyperpolarizing

one type of potential is a graded potential, which is categorized by a ______ event, they are ________ and _________, they _______ with distance and time, they help to dictate whether or not an ______________ ___________ will occur, and they have a _________ amplitude and duration, they can be _________ or ___________

active, self-regenerating, constant, suprathreshold (all or nothing), depolarizing, action, Calcium

one type of potential is an action potential, they are _____ and _______-______, they are _______ through a distance/time, they are _______ events, they are largely ________, and they are said to more accurately be a potential for ________ via _________ 

threshold

occurs when Na+ permeability briefly but massively eclipses K+ permeability

graded potentials, action potentials

both _________ and __________ are membrane voltage gated, propagate down neuronal processes, and are transient events

after hyperpolarization (AHP) phase

a neuron needs this phase to unblock Na+ channels, close K+ channels, reset the ionic gradient, and lead to a relative refractory period

myelination

process needed to insulate/isolate longer axons

propagation

occurs via opening of sodium channels via depolarization across the axon/surrounding area, goes in one direction due to refractory periods for unmyelinated axons

unmyelinated neurons

in these neurons each step of action potential must happen every few microns, slow a

axon hillock/initial segment/trigger zone

where an action potential begins

internode

area where myelin is present

node of ranvier

axon areas not covered by myelin

saultinary conduction

conduction that occurs in myelinated axons, signal jumps between nodes of ranvier 

oligodendrocytes

myelinate axons in central nervous sytem

schwann cells

myelinate axons in peripheral nervous sytem

electrical synapse

connected by gap junctions, electrical signal, causes a “coupling potential” in which pre and post synaptic cell mirror each other’s behavior, bidirectional signal

chemical synapse

anterograde movement, characterized by vesicles that release neurotransmitters, post synaptic cell does not need to mirror pre synaptic cell

vesicle exocytosis

characterized by filling, translocation, docking, priming, and fusion with membrane

vesicle endocytosis

characterized by translocation, clathrin coating, fission with presynaptic membrane via dynamin coating, clathrin uncoating, and recycling via a variety of pathways

SNARES

proteins responsible for some docking, priming, and fusion events

V-SNARES

SNARES responsible for vesicular processes, located in vesicles

T-SNARES

SNARES located on target membrane (terminal membrane)

botox

toxin that cleaves SNARES, locks muscles in an uncontracted position

synaptotagamin

calcium receptor in neuron

acetocholine

muscle neurotransmitter

neurocrine

signal between pre and post synaptic NEURONS only

chemically gated ion channels

a.k.a ligand gated ion channels, ionotropic receptors, low amplification, only open ion channels, fast, short lasting, receptor and channel are the same, usually excitatory signals (depolarizing)

g-protein coupled receptors 

a.k.a. metabotropic receptors, engage in slow acting, multipstep, metabolic effects, long term, receptor and protein are different, can open and close other ion channels

nicotine acetocholine receptor

ligand gated ion receptor in which 2 acetylcholine needed to open, contains 5 subunits, allows many different cations to flow, leads to depolarization

muscarinic acetylcholine receptor

g protein coupled receptor, metabotropic, can link indirectly to K+ channels, leading to hyperpolarization

inhibitory signal, excitatory signal

below threshold = ___________, above threshold = ____________

sumation

adding up/integration of several signals to help reach threshold

spatial summation

summation via multiple axons at the same time on the same cell

temporal summation

summation by quick stimulus of same neuron from same axon

integrator

the axon initial segment is the ______ in the response loop

acetylcholine esterase

enzyme responsible for cleaving acetylcholine for action termination at neuromuscular junction

Glutamate (Glu)

neurotransmitter found everywhere in CNS, excites neuronal firing, main excitatory transmitter

GABA

neurotransmitter everywhere in CNS, known for inhibition, main inhibitor

Glycine

neurotransmitter scattered in CNS, big inhibitor

acetylcholine

neurotransmitter found in nerve-muscle connections, autonomic synapses, some CNS synapses, stimulates muscle contraction, slows heart rate, rest and digest

norepinephrine (NE)

neurotransmitter found in autonomic synapses, some CNS synpses, speeds heart rate, fight or flight, emotion, arousal

serotonin (5-HT)

neurotransmitter found in pons, medulla, etc., has broad effects

dopamine

neurotransmitter found in basal ganglia, frontal cortex, limbic “emotional” system, plays role in motivation and reward

neuromuscular junction

presynaptic neuron goes to postsynaptic skeletal muscle cell

excitability, contractility, elasticity, and extensibility

four special muscle characteristics

innervated

term for when motor neuron is connected with muscle fiber, that muscle fiber is ___________

Henneman’s size principle

as force increases in a muscle, more and larger motor units are recruited to generate larger force

s-type motor units

smallest motor units, high excitability, 1st to be recruited

fatigue resistant fast motor units

2nd to be recruited, bigger than s type, average excitability

fast, fatigable

very big motor units, low excitability, fatigue fast, strongest

muscle tone

continued, slow, steady, low level of contraction that stabilizes joint and maintains muscle health

motor end plate

region of sarcolemma (plasma membrane of sarcomere) across from motor neuron with lots of receptors in folded/indented formations to increase surface area

diffuse

all neurotransmitters eventually ________ away

sarcolemma

plasma membrane of muscle cell

sarcoplasm

cytoplasm in muscle cell

sarcoplasmic reticulum

smooth endoplasmic reticulum of muscle cell, mainly calcium storage, release, and reputake

T-tubules

deep invaginations of sarcolemma, extend into sarcoplasm in honeycomb structure to propagate action potential deep into muscle cell

terminal cisterna

calcium filled sacs at end of sarcoplasmic reticulum

DHP receptor

voltage sensitive protein in t-tubule that opens in response to action potential

RyR Receptor

mechanically gated protein that opens in terminal cisternae in response to DHP receptor opening 

troponin - C

recognizes calcium in muscle cells, causes tropomyosin to move off of actin sites, located on actin double helix

sarcomere

functional unit of skeletal and cardiac tissue

z lines

end of sarcomere

double helix

actin is arranged in a _________

G actin

monomer form of actin

F actin

filamentous form of actin

tropomyosin

wraps thin filaments, covers up myosin binding sites on actin

m line

middle line of sarcomere

A band

length of myosin

i band

actin not overlapping with myosin

h zone

myosin not overlapping with actin

cap-z

anchors actin to z lines

titin

anchors myosin to z lines, attached to myosin head, also provides elasticity for myosin filament to return to optimal resting length (ORL)

nebulin

orients actin thin filaments

catalytic core and lever arm

2 parts of the myosin head structure

rigor mortis

ailment in which ATP is not present to release myosin head from actin filament, causes stiffness after death

alpha actinin

Z lines also contain this protein, which is important for cross bridge formation

creatine kinase

protein that the m line helps to create, responsible for phosphorylating ADP to ATP, depleted in muscle fatigue

optimal resting length

sarcomere length that produces the greatest tension/force

twitch

single contraction/relaxation cycle

latent period

action potential present in muscle, no contraction

contraction phase

muscle contracts