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Anatomy & Physiology 210 > Chapter 12 Nervous System > Flashcards

Chapter 12 Nervous System Flashcards

1
Q

What are the two divisions of the nervous system?

A

Central nervous system – brain and spinal cord

Peripheral nervous system – all other

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2
Q

What are the two functional divisions of the peripheral nervous system.

A

Sensory afferent division:
Somatic afferent fibers-(superficial info) convey impulses from skin skeletal muscles and joints.
Visceral afferent fibers-(deep info) convey impulses from visceral organs

Motor efferent division:
Transmits impulses from the CNS to effector organs

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3
Q

What are the two motor divisions of the PNS?

A

Somatic nervous system (voluntary)

Autonomic involuntary

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4
Q

What are the two divisions of the autonomic nervous system?

A

Sympathetic – rapid response short-term

Parasympathetic – maintain normal resting position.

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5
Q

What are the two principal cell types? And the names of them?

A 
Neuron
Neuroglia:
Astrocyte (CNS)
microglia (CNS)
Ependymal cells (CNS)
oligodendrocytes (CNS)
satellite cells(PNS)
Schwann cells(PNS)
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6
Q

What are microglia cells?

A

Small, ovoid cells with thorny processes.

Migrate toward injured neurons. Phagocytize microorganisms and neuronal debris.

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7
Q

Explain astrocytes.

A

Most abundant, versatile, and highly branched Glial cells.
Support and brace neurons.
Guide migration of young neurons. Help determine capillary permeability. Aid the blood brain barrier.

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8
Q

What are ependymal cells?

A

Cells that line the cerebrospinal fluid filled cavities

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9
Q

Explain oligodendrocytes.

A

Have processes that form myelin sheaths around CNS nerve fibers.

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10
Q

Explain satellite cells and Schwann cells.

A

Satellite – surround neuron cell bodies in the PNS.

Schwann – surround peripheral nerve fibers and form myelin sheaths.
Vital to regeneration of damage peripheral nerve fibers.

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11
Q

What cells are absent from the vomit center of the brain and why?

A

Astrocytes.
Because the blood brain barrier breaks down so the brain can tell the body to remove it by vomiting. Because it doesn’t want more toxins entering the brain.

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12
Q

What are the special characteristics of neurons?

A

Long lived, amitotic, high metabolic, plasma membrane functions in: electric signaling and cell to cell interactions during development.

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13
Q

Clusters of cell bodies (Gray matter) are called _______ in the CNS, and ________ in the PNS.

A

Nuclei

ganglia

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14
Q

What are the three functions of the nervous system?

A

Sensory input (smell touch sight)

Integration (appropriate response)

Motor output (sends message)

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15
Q

What are bundles of processes (white matter) called in the CNS and PNS?

A

Tracts-CNS

Nerves-PNS

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16
Q

What is the myelin sheath function?

A

Protect and electrically insulate the axon, increased speed of nerve impulse transmission.

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17
Q

Explain the myelin sheaths of the CNS

A

Formed by oligodendrocytes not the whole cell.
Nodes of ranvier present.
No neurilemma.
Thinnest fibers unmyelinated.

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18
Q

What is white matter and gray matter?

A

White – (output) dense collections of myelinated fibers: nerves and tracts (axon).

Gray- (input) cell bodies in dendrites and synapses

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19
Q

What are the three structural classifications of neurons?

A

Multipolar – (efferent) one axon several dendrites. Most abundant
Motor neurons and interneurons

Bipolar- one axon one dendrite on opp sides of soma. Rare (retinal and olfactory)

Unipolar-single short process with two branches. Mostly sensory neurons (afferent)

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20
Q

What are the three functional classifications of neurons?

A

1-sensory (afferent): transmit impulses from sensory receptors towards the CNS.
2-Motor (efferent): Carry impulses from the CNS to effectors.
3-Interneurons (processing): shuttle signals through CNS pathways. Connect sensory neurons to motor neurons. Most are entirely within the CNS.

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21
Q

Name three neuron functions.

A

1: neurons are highly irritable.
2: respond to adequate stimulus by generating an action potential (nerve impulse).
3: impulse is always the same regardless of stimulus.

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22
Q

What are the principles of electricity?

A

Opposite charges attract each other.

Energy is required to separate opposite charges across a membrane.

Energy is liberated when the charges move towards one another.

If opposite charges are separated, the system has potential energy.

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23
Q 
Define the following vocabulary terms:
Voltage (V)
potential difference 
current (I)
resistance (R)
insulator 
conductor
A

Vol: Measure of potential energy generated by separated charge

PD: voltage measured between two points

Cur: The flow of electrical charge (ions) between two points

Res: hindrance to charge flow (plasma membrane)

Insul: substance with high electrical resistance

Con: substance with Low electrical resistence (higher current)

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24
Q

What is the equation to solve for current (I) ?

A

I=v/r

Or

V=i*r

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25
Q

Proteins serve as membrane ion channels. Name the two main types of ion channels and their function.

A

1: leakage (non-gated) channels – always open
2: gated channels (three types):
a. Chemically gated (ligand-gated) channels-Open with binding of a specific neurotransmitter.
b. Voltage gated channels: Open and close in response to changes in membrane potential.(electrical current)
c. Mechanically gated channels: Open and close in response to physical deformations of receptors. (Shape)

26
Q

When gated channels are open ions diffuse quickly across the membrane along their electrochemical gradient which is what for chemical and electrical?

A

Chemical concentration gradients from high concentration to low.

Electrical gradient toward opposite electrical charge.

27
Q

What are two types of membrane potential signals?

A

1: graded potential – incoming short distance signals (dendrites/soma. Variable size signal)
2: action potentials – long-distance signals (axons. Same size of signal)

28
Q

After repolarization, hyperpolarization can occur. How?

A

Some potassium channels remain open, allowing excessive potassium reflux.

29
Q

What restores the resting electrical conditions of a neuron? What restores the resting ionic conditions?

A

Repolarization

Sodium potassium pump

30
Q

What are the three threshold stimuluses?

A

Sub threshold stimulus – weak local depolarization that does not reach threshold.

Threshold stimulus – strong enough to push the membrane potential toward and beyond the threshold.

Action potential – all or none phenomenon.

31
Q

All action potentials are alike and are independent of stimulus intensity?

A

True

32
Q

How does the CNS tell the difference between a weak and strong stimulus?

A

Strong stimuli can generate action potentials more often than weaker. They’re all the same size just increased volume for a strong signal.

33
Q

What ensures that action potential is all or none event in refractory period?

A

Time from the opening of the sodium channels until the resetting of channels is an absolute refractory period. Enforces one way transmission of nerve impulses

34
Q

What follows an absolute refractory period?

A

Relative refractory period.

Most sodium channels @ resting state.

Some potassium channels open.

Repolarization is occurring.

35
Q

What are two ways conduction velocity varies.

A

1: effect of axon diameter: less resistance to local current flow and faster impulse conduction.
2: effect of myelination: continuous conduction in myelinated axon is slower than saltatory conduction in myelinated axons.(myelin sheath insulate and prevent leakage of charge, salted Tory conduction is 30 times faster.)

36
Q

Explain multiple sclerosis.

A

An autoimmune disease that mainly affects young adults.
Symptoms are: visual disturbances, weakness, loss of muscular control, speech disturbances and urinary incontinence.
Myelin sheaths in the CNS become nonfunctional scleroses.
Shunting and short-circuiting of nerve impulses occurs.
Impulse conduction slows and eventually ceases.

37
Q

What are three ways a neurotransmitter is terminated?

A

Degradation by enzymes.

Reuptake by astrocytes or axon terminal.

Diffusion away from the synaptic cleft.

38
Q

What is the rate limiting step of neurotransmission?

A

Synaptic delay

39
Q

What are the two postsynaptic potentials?

A

1: EPSP – excitatory postsynaptic potential
2: IPSP – inhibitory postsynaptic potentials

40
Q

What does EPSP help trigger?

A

AP at the axon Hillock if of threshold strength and opens voltage gated channels. Depolarization

41
Q

What does IPSP do?

A

hyperpolarization.

42
Q

What are two types of summations?

A

Temporal summation: one or more presynaptic neuron transmit impulses in rapid fire order.

Spatial summation: postsynaptic neuron is stimulated by a large number of terminals at the same time.

43
Q

In neurotransmitter chemical classes, Biogenic amines include?

A

Catecholamines: dopamine, norepinephrine, epinephrine

Indolamines: serotonin and histamine

44
Q

Neurotransmitter chemical class amino acids include?

A

GABA

Glycine

aspartate

glutamate

45
Q

Neurotransmitter chemical class peptides include?

A

Substance P: mediator of pain signals

Endorphins: natural opiates, reduce pain perception

46
Q

Neurotransmitter chemical class gases include?

A

Nitric oxide

Carbon monoxide

47
Q

Neurotransmitter chemical class lipid includes?

A

Endocannabinoids:

Lipid soluble, synthesized on demand from membrane lipid.
Binds with G protein – coupled receptors in the brain.
Involved in learning and memory.

48
Q

A neurotransmitter direct action receptor example?

A

Ach

(neurotransmitter binds to channel linked receptor and opens ion channels)

Rapid response

49
Q

What is indirect neurotransmitter action?

A

Neurotransmitter binds to a G protein linked receptor and acts through an intracellular second messenger.

Long lasting effects

50
Q

What are two types of neurotransmitter receptors?

A

Channel linked receptors

G protein linked receptors

51
Q

What is a simple neuronal pool? And the two zones?

A

Single presynaptic fiber branches in synapses with several neurons in the pool.

Discharge down – neurons most closely associated with incoming fiber.

Facilitated zone – neurons farther away from incoming fiber.

52
Q

What are the three types of circuits in neuronal pools?

A

Diverging circuit

converging circuit

Reverberating circuit

53
Q

Explain diverging circuit.

A

One incoming fiber stimulates an ever increasing number of fibers, often amplifying circuits.

54
Q

Explain converging circuit.

A

Many input to common output.

55
Q

Explain reverberating circuit.

A

Chain of neurons containing collateral synapses with previous neurons in the chain.

56
Q

What is the (five) pattern of neural processing

A 
1-receptor
2 sensory neuron
3-integration center
4-Motor neuron
5-effector
57
Q

What is parallel processing?

A

Diverging circuit. Input travels along several pathways, one stimulus promotes numerous responses.

58
Q

The nervous system originates from the neural tube and neural crest formed from ________.

A

Ectoderm

59
Q

The neural tube becomes the _______.

A

CNS ( brain to spine)

60
Q

What are the three phase processes of differentiation of neurons?

A

Proliferation: appropriate number of cells created.

Migration: cells become amitotic and migrate.

Differentiation: neuroblast become proper motor, sensory, or Interneurons.

61
Q

About two thirds of neurons die before birth. Name three reasons why.

A

Death results in cells that failed to make functional synaptic contacts.

Many cells also died due to a pop ptosis during development.

Those that remain constitute the majority of the neurons for life.

Anatomy & Physiology 210 (21 decks)

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