Chapter 11 Nervous System Flashcards by Moeka Nakagawa

KNOW THE ORGANIZATION AND FUNCTIONS OF EACH DIVISION OF THE NERVOUS SYSTEM:
CENTRAL NERVOUS SYSTEM (CNS)

PERIPHERAL NERVOUS SYSTEM (PNS)

**not in lecture WHAT DO SOMATIC AND AUTONOMIC DIVISIONS OF THE PNS INNERVATE?

not in lectureWHAT ARE THE TWO DIVISIONS OF THE AUTONOMIC NERVOUS SYSTEM?

CNS = brain and spinal chord
-integration and command center

PNS =. paired spinal (31) and cranial nerves (12)
-carry messages to and from the brain

somatic division innervate skeletal muscles
autonomic divisions innervate smooth muscles, cardiac muscles, glands
Parasympathetic: conserves energy
Sympathetic: mobilizes

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KNOW FUNCTIONS OF NEUROGLIAL “SUPPORTING CELLS”.

WHICH ARE IN THE CNS?
WHICH ARE IN THE PNS?

CNS = astrocytes, microglia, ependymal cells, oligodendrocytes
PNS = satellite cells, Schwann cells

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astrocytes

CNS - support & brace neurons and their capillarie

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microglia

CNS - phagocytize microorganisms and neuronal debris

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ependymal cells function & location

CNS - has cillia that moves and circulate the cerebral spinal fluid
-lines cavitites of the brain and spinal column

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oligodendrocytes

wrap CNS axons forming insulating myelin sheaths

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Satellite cells. What is its function? What is it similar to in the CNS?

PNS

surround cell bodies in the PNS
similar to astrocytes in the CNS

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Schwann cells What do they form? They are vital to _____. What is it similar to in the CNS?

form myelin sheaths
vital to regeneration of damaged peripheral nerves
similar to oligodendrocytes in the CNS

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WHAT IS THE FUNCTION OF THE MYELIN SHEATH? (2)

WHAT CELLS PRODUCE IT IN THE CNS?

IN THE PNS?

protects and insulates neuron
increase speed of nerve impulse transmission
CNS = oligodendrocyte
PNS = schwann cells

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What is the node of Ranvier?

Why does the action potential (AP) travel faster in myelinated fibers?

What is this process called

myelin sheath gaps between schwann cells

- voltage Na channels in nodes of ranvier allows Na to rush in (called saltatory conduction)

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What part receives incoming stimuli and generates a graded potential (GP)?

What part generates an action potential (AP)?

dendrites

- axon

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What are Nissl bodies in the cell body?

RER in neurons

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What is a neuron? Know the anatomy (3) and general characteristics (3) of a neuron. (We used a motor neuron as our example.)

-excitable cells that transmit electrical impulses

structural unit of the nervous system
large, highly specialized cells that conduct impulses
have cell body and processes
extreme longevity
amiototic/do not regenerate (damage = paralysis)
high metabolic rate (requires continsous glucose & O2)

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Which neurons are structurally unipolar?

Which are bipolar?

What neurons are multipolar?

unipolar = sensory neurons (like temperature from touch)
biopolar = retina of the eye & organs of sensory organs
multipolar = motor neurons & interneuron

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What is the function of a: motor neuron; sensory neuron ; interneuron

motor neurons = carry impulses from CNS to the effectors
sensory = transmits impulses from sensory receptors to CNS
interneurons = shuttle signals between motor and sensory neurons (most neurons are this type)

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What creates the resting membrane potential? (3, 4) What voltage is it?

differences in ionic makeup of ICF and ECF &
ICF has high Cl- and Na+
ECF has high K+ and - proteins
differential permeability of the plasma membrane
impermeable to negative proteins
slightly permeable to Na+ & K+ (leakage proteins)
freely permeable to Cl-

-70mV

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What is depolarization? (2)

The entry of what ion causes depolarization?

decrease in membrane potential
inside of cells becoming less negative
voltage gated Na+ opens

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What is repolarization? (2)

The exit of what ion causes repolarization?

increase in membrane potential
becomes more negative
K+ voltage gated channels open

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What is hyperpolarization?

The exit of what ion causes hyperpolarization?

influx of excessive K+

- becomes more negative than resting membrane potential

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What are 3 types of gated channels in neuron membranes?

ligand-gated: open when neurotransmitters attach to the receptors
voltage-gated: receptors open with change in voltage
leakage channels: always open, allows Na+ and K+ (more K+ leakage channels than K+) to wiggle through

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What are the absolute and relative refractory periods of a neuron? Are neurons able to respond to stimuli?

What does an absolute refractory period ensure? (2)

Repolarization/hyperpolarization/depolarization is occurring during a relative refractory period?

absolute refractory period

time from opening of Na channels until reset
neuron unable to respond to stimuli
ensures reaching of AP
ensures one way transmission of impulses

relative refractory period

Na return to resting state & some K channels still open
repolarization occurring
only exceptionally strong stimulus could generate an AP

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What is a synapse?

-junction that mediates information transfer from one neuron to another neuron of an effector cell

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Know what happens at a chemical synapse.

The entry of what ion through voltage-gated channels in the axonal terminal stimulates the vesicles containing neurotransmitter (NT) to fuse with the axonal membrane of a presynaptic membrane?

By what process is the NT released into the synaptic cleft?

NT binds to receptors on the _______________ neuron.

The NT causes the generation of what kind of potential on the postsynaptic neuron?

Ca
exocytosis
post-synaptic neuron
graded potential

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Presynaptic and postsynaptic neurons transmits impulses to/away from synapse?

presynaptic - conducts impulses toward the synapse

- postsynaptioc - transmits impulses away from synapse

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***not in lecture*** What are 3 ways the neurotransmitter is removed from the synaptic cleft?

1. diffusion away from synaptic cleft 2. degradation - by enzymes 3. reuptake - by astrocytes or axon terminal

What is a graded potential? What do depolarization and hyperpolarization mean in terms of the neuron being likely to “fire”?

- short-lived, localized changes in membrane potential - depolarization means neuron fired - during hyperpolarization, neurons do not fire

What is an action potential? Where does it occur?

- brief reversal of membrane potential | - occurs in sarcolemma of muscles & AXONS of neurons

How are graded potentials and action potentials different and where on the neuron is each usually generated?

- graded potential = dendrites, local change | - action potential = axons of neuron, spreads through neuron

An AP is generated when voltage gated _______________ channels open. Where does the voltage come from?

Na+ | influx of Na+ ions into the cell

Speed of AP transmission depends on what 2 factors? They are faster when _____.

diameter (bigger is faster) & degree of myelination (more insulation is faster) of nerve fibers

What are A (just know this), B, and C nerve fibers?

thickest, quickest nerve fiber

Where are electrical synapses found in the body? In electrical synapses, ions can rapidly enter cells to depolarize them because they move through membrane junctions called ____________________________ .

- embryonic nervous tissues & some brain regions | - gap junctions

What is an IPSP and an EPSP? ***Are they a graded or an action potential? Is each generated by depolarization or hyperpolarization?

IPSP = inhibitory post synaptic potential -hyperpolarization when K leaves the cell or Cl- enters cell EPSP = excited post synaptic potential - inside becomes positive as ligand gated channels open and Na enters and K leaves (net +) - graded potential (depolarization) that helps trigger AP if threshold is reached -both graded potential

Dopamine is a neurotransmitter (NT) that is deficient in ___________________ disease.

parkinson's disease

The antidepressant Elavil acts as selective ____________________ (2) uptake inhibitor, allowing the NT to remain in the synaptic cleft longer.

norepinephrine/adrenaline/epinephrine, serotonin

What NT is excitatory at the neuromuscular junction?

acetylcholine

What neurotransmitter is thought to play a role in sleep and appetite disorders, migraines, and its re-uptake is blocked by the antidepressant Prozac?

seratonin

What is the main inhibitory NT in the brain?

GABA

Why is glutamate called “the stroke NT”?

excessive release from damaged neuron is toxic to brain

What NT is a mediator of pain signals? How?

endorphins, inhibiting substane P

What are the effects of the endorphin? What are they naturally? What 2 drugs mimick this?

- natural opiates that reduce pain by inhibiting substance B | - mimicked by heroin & morphine

What do Na/K pumps do? How many Na pumped? K? In which direction?

create resting potentials | 3 Na out, 2 K in

What causes multiple sclerosis? What does it form? What are its symptoms? (5)

- demyelinations of CNS neurons - forms thick scars (nonfunctional sclerosis) - visual disturbances, weakness, loss of muscular control, speech disturbances, urinary incontinence

What are the 2 different types of synapses?

- axodendritic - between axon & dendrite | - axosomatic - between axon & soma

LSD blocks the inhibitory activity of _____.

serotonin

Excessive dopamine causes _____.

scizophrenia

The reuptake of these 2 neurotransmitters are blocked by cocaine to produce a feel good effect.

norepinephrine and dopamine

Acetylcholine is _____ in skeletal muscle but _____ in cardiac muscle (_____ receptors)

excitatory, inhibitory, beta-1 receptor

action potential numbers - resting membrane potential - graded potential - action potential - hyperpolarization

-70 -55 +35

Small/big/polar/non-polar molecules are allowed through leakage/ligand gated/voltage gated channels. (2)

- leakage channels: small, non-polar | - gated channels (ligand and voltage channels): big, polar

What are the 4 main voltage-gated channels used for muscle contraction and sending neuro impulses?

Na+, K+, Cl-, Ca++

****What is diffusion? What are 3 different kinds of diffusion?

- movement of molecules from high to low concentration - simple diffusion of small/nonpolar molecules through leakage proteins - facilitated diffusion for larger molecules - receptor-mediated difussion: molecules (like aa and glucose) bind to receptor and open the pathway

What are the 2 kinds of excitatory cells? What does that mean?

muscles (myocyte), neurons | -can be excited to do something

5 steps of action potential (2 pre-step)

1. action potential opens voltage-gated Ca++ on the neuron. the Ca++ goes to the terminal button 2. acetylcholine released into the synaptic cleft 1. RMP - negative on the inside, positive on the outside 2. Graded potential - Acetyl choline attaches to the ligand gated Na+ channel, the receptor opens and lets Na+ inside, making the charge more positive. Creates graded potential, which is a local change 3. Depolarization - once the threshold is reached, the graded potential opens up the voltage-gated Na+ channels, to let even more Na+ inside, rapidly. This makes all of the cell membrane positive. In this stage, action potential has occurred. 4. Repolarization - voltage-gated Na+ channels close, and voltage-gated K+ channels open and let K+ go outside, making the inside negative again. 5. Hyperpolarization - cell becomes more negative than original as K+ channel remains open. Here, cells cannot do anything and become inhibited

Not in objectives What is the pathway of nervous system (3)

1. sensory input - information about changes gathered via afferent pathway 2. integration - interpretation of sensory input 3. motor output - activation of effector organs to produce a response

Not in objectives Where are interneurons located? What brain functions is it used to do? (3)

- CNS (brain) | - memory, thinking, decision making

What are the 2 types of nerve cells?

neurons & neuroglia (supporting celles)

Quiz Long axons are called _____.

nerve fibers

talked about in class neurons can form synapses with these 3 things

muscle, galnds, neurons

What is a neurilemma?

peripheral bulge of Schwann cell cytoplasm

_____ creates an electrical current and voltage changes across the cell membrane

ion flow

chemical/electrical synapses are more common

chemical

chemical synapses are highly _____

specialized

A synaptic cleft ensures _____ between neurons.

unidirectional communication

The cell membrane is 75 times more permeable to _____ than _____ through leakage channels

K+, Na+

changes in _____ are signals.

membrane potential

Talked about in class give 3 sentences of graded potentials

1. local change 2. short distance signals 3. decrease in magnitude with distance because ions diffuse through leakage channels

AP does/does not decrease in magnitude over long distance.

does not

AP is a brief reversal of membrane potential with a total amplitude of _____ mV.

100

True or false AP is an all or none phenomenon.

true

Meylination prevents _____ of charge.

leakage

The strength of graded potentials depend on _____. (2)

amount of neurotransmitter released, time the neurotransmitter is in the area

a signle EPSP can/cannot induce an action potential. EPSP must ____ to reach threshold by either increasing the ____ or _____. IPSP ____ EPSP summation

- cannot - EPSP must summate by increasing the frequency of stimuli or gathering multiple stimuli from different sources - IPSP and EPSP cancels each other out

_____ are the language of the nervous system.

neruotransmitters

True or false. Most neurons make 2 or more neurotransmitters

true

Which neurotransmitters produce the feel good effect? (4)

norepinephrine, dopamine

_____ cells are vital for damaged peripheral nerves

schwann cells