Physiology Quiz #2

what is a local grated membrane potential?

stimulus/signal causes a change in membrane potential in a dendrite (gated channels signaled to open)

Threshold potential

threshold or trigger zone or membrane potential that a cell must reach to send the action potential

Excitatory signal

a signal that brings you closer to the threshold

inhibitory signal

signal that brings you further from the threshold

Ionotropic receptors are…

ligan gated ion channels, and membrane potential changes

Metabotropic receptors are…

not ligan gated ion channels, can change gene expression, enzyme activity, and ion movement

____ action potential frequency _____ neurotransmitters in the synapse, thus ______ signal strength

higher, increases, increasing

what determines the absolute refractory period?

the duration that the inactivation gate stays closed

what limits action potential frequency?

inactivation gate on the voltage gated ion channel

What is the absolute refractory period?

the time after the start of an action potential that another action potential cannot be initiated, (inactivation gate stays closed until the end of this period)

What is the relative refractory period?

time from the end of the absolute refractory period to the resting membrane potential

what is (EPSP)?

Excitatory post-synaptic potential: causes post-synaptic cell to have an increase in membrane potential

what is (IPSP)?

Inhibitory post-synaptic potential: causes the post-synaptic membrane potential to decrease

myelin sheath is made up of…

glial cells

Glial cell types (group 1)

Oligodendrocytes (CNS) and Schwann cells (PNS)

oligodendrocytes can myelinate_____ axons

multiple

schwann cells can myelinate ____ axon

one

purpose of myelin on axons

to increase the speed of an action potential

glial cell type (group 2)

Astrocyte (CNS) and Satellite (PNS)

what do astrocytes and satellites do?

support cells neurons by helping to get nutrients to the neuron

glial cell type (M)

Microglia (CNS)- clear out extra protien in extracellular fluid

glial cell types (ep)

Ependymal cells (CNS)- circulate cerebrospinal fluid

2 parts of the nervous system

Afferent (receiving signals) and Efferent (sending signals)

2 parts of efferent nervous system

Somatic (motor) and Autonomic

2 parts of autonomic nervous system

sympathetic and parasympathetic

sympathetics characteristics and actions

higher heart rate, higher blood pressure, higher ventilation, dilated pupils, “fight or flight”, blood towards heart liver and muscles

parasympathetics characteristics and actions

lower heart rate, lower blood pressure, lower ventilation, higher gut motility, constricted pupils, “rest and digest”

what is conduction speed?

speed of an action potential being pushed down the axon

fast conduction speed=

low ratio of (intracellular resistance)/(membrane resistance) * ease of going down axon, less leaks out

slow conduction speed

high ratio of (intracellular resistance)/ (membrane resistance) *harder for the positive charge to go down the axon, more leaks out

2 mechanisms that have increased conduction speed

1. big axons (increase of diameter has lower intracellular resistance)

2. Myelinated axons (insulation increases conduction speed)

nodes of ranvier

gaps in between myelin for the ion channels on the axon

What is a ganglion?

cluster of nerve cells in the PNS, act as a relay station

what kind of receptor binds with Acetylcholine in the post-ganglionic cell of the parasympathetic pathway?

Nicotinic Acetylcholine receptor (ionotropic)

what kind or receptor binds with acetylcholine on the target cell in the parasympathetic pathway?

Muscarinic Acetyl choline receptor (metabotropic)

what is released by the pre-ganglionic cell in the sympathetic pathway?

acetylcholine

which receptor binds with acetylcholine in the post-ganglionic cell in the sympathetic pathway?

Nicotinic acetylcholine receptor (ionotropic)

what is released by the post-ganglionic cell in the sympathetic pathway?

norepinephrine

what receptors bind with norepinephrine in the sympathetic pathway?

alpha or beta adrenergic receptors (metabotropic)

where does the pre-ganglionic cell synaps in the adrenal medulla sympathetic pathway?

within the adrenal medulla

what is released by the pre-ganglionic axon in the renal medulla?

Acetyl choline

What types of cells make up the adrenal medulla?

Chromaffin cells (modifed post-ganglionic neurons)

why can’t chromaffin cells synapse with a target cell?

because they dont have an axon

what is released by the chromaffin cells in the renal medulla sympathetic pathway?

the hormone epinephrine

What is the structural difference between epinephrine and norepinephrine?

epinephrine has an extra acytl group

3 muscle types

smoothe, cardiac, skeletal

Cytoskeleton cells are made of…

microfilaments (actin filaments), microtubules, and intermediate filaments

muscles use ___ and ___ to generate force

actin and myosin

which type of myosin is most common in muscles?

Myosin II

Actin and Myosin Generate force through the ______

sliding filament model

Step 1. of the actin filament model

ATP binds to myosin causing myosin to release actin

Step 2. of the actin filament model

Myosin hydrolyzes ATP to ADP and Pi causing the myosin head to extend and rebind actin

Step 3. of the actin filament model

myosin releases Pi causing a power stroke

Step 4. of the actin filament model

ADP is released making room for the subsequent ATP

Temporal summation

integration of several signals in quick succesion

spacial summation

integration of multiple signals received simultaneously at different dendrites

Action potential

an electrical signal propogated down the axon