Nervous System Flashcards

1
Q

The Nervous System

A

One of the two major control systems of the body mediating systemic homeostatic processes

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2
Q

skipped

what homeostatic processes does the NS mediate? (4)

A

muscle contraction
integration of blood oxygen, carbon dioxide, and pH levels via respiratory activity
regulation of volumes and pressures in the circulation via cardiovascular and urinary function
digestive system motility and secretion

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3
Q

the NS works along with — to Maintain Systemic

Homeostasis

A

Endocrine System (ES)

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4
Q

NS is — fix to homeostatic disturbance and ES is —

A

quick

slower long term maintenance

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5
Q

NS Functional unit =

A

Neurons

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6
Q

Neuroglia =

A

support cells for neurons

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7
Q

NS uses a combination of (2) to

communicate information around body

A

chemical and electrical signals

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8
Q

dendrites are simulated by (2)

A

environmental changes or the activities of other cells

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9
Q

cell body

A

contains the nucleus and mitochondria, ribosomes, and other organelles and inclusions

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10
Q

axon

A

conducts nerve impulse (AP) toward synaptic terminals

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11
Q

synaptic terminals affect

A

another neuron or effector organ (muscle or gland)

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12
Q

nissl bodies

A

clusters of ribosomes found in the cell body

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13
Q

Many neurons have axons

that are —

A

myelinated

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14
Q

— formed by neuroglia cells

A

Internodes

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15
Q

– form myelin for axons in CNS

A

Oligodendrocytes

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16
Q

– form myelin for axons in PNS

A

Schwann cells

17
Q

Internodes separated by small
segments of axon not covered
in myelin –

A

Nodes of Ranvier

18
Q

function of Nodes of Ranvier

A

Speed up the rate of nerve impulse conduction (Saltatory conduction)

19
Q

types of neurons (structural classification) (4)

A

anaxonic
bipolar
pseudo unipolar
multipolar

20
Q

Types of Neurons (Functional Classification) (3)

A

sensory
motor
interneurons

21
Q

Sensory Neurons (pseudounipolar neurons, bipolar) (4)

A

Afferent division of PNS
Carry sensory information from reflex receptor to CNS
Dendrites/Cell body in PNS
Axons typically myelinated and extend into CNS

22
Q

Motor Neurons (Multipolar neurons) (4)

A

Efferent division of PNS
Carry motor commands from CNS to EFFECTORS
Dendrites/Cell body in CNS
Axons typically myelinated, extend into PNS and synapse
with effectors

23
Q

Interneurons (Multipolar, Anaxonic) (3)

A

Found only in the CNS
Carry information from one neuron to another
Integration

24
Q

Information flows in

A

one direction

25
Action Potentials (AP): (5)
–Always the same (depolarization followed by repolarization) with no change in strength or size as they travel along the membrane –All-or-none –Triggered at Axon Hillock when Threshold Potential reached (Vm at which AP triggered; typically around -50mV)) –Always propagates along cell membrane of axon from axon hillock toward axon terminals –Relatively fast changes in Vm
26
Graded Potentials (GP): (3)
–Small changes in membrane potential of variable strength/amplitude –Only travel a short distance along membrane and lose strength as they travel –Often last longer than APs
27
examples of GP (2)
EPSP | IPSP
28
EPSP
Excitatory postsynaptic potentials (depolarizations); moves Vm towards threshold potential; increases likelihood of AP
29
IPSP
Inhibitory postsynaptic potentials (hyperpolarizations); moves Vm away from threshold; decreases likelihood of AP
30
Depolarization
Vm becomes more positive (less | negative). EPSPs
31
Repolarization
Vm returns to resting value
32
Hyperpolarization
Vm becomes more negative than resting. IPSPs
33
Which ion channels, if | opened, cause an EPSP? (2)
Na | Ca
34
Which ion channels cause an IPSP? (2)
K closed | Cl open
35
skipped | Example of a Graded Potential becoming an Action Potential in a Neuron (graph, A-F)
A. Resting Membrane Potential B. EPSP depolarizes membrane C. EPSP reaches threshold and causes voltage-gated Na+ channel to open—transition from graded potential to action potential (axon hillock) D. Depolarization; Na+ moves into the cell through open Voltage-gated (VG)-Na+ channels. Activated via positive feedback (see slide 16). E. VG Na+ channels close & slow voltage-gated K+ channels open F. Repolarization; K+ moves outside of the cell through open VG K+ channels G. Hyperpolarization; VG K+ channels still open H. Voltage-gated K+ channels close A. Resting membrane potential
36
Activation gate
Closed at resting Vm, quickly opens at threshold depolarization
37
Inactivation gate
Open at resting Vm, slowly closes at threshold depolarization
38
Voltage-gated K+ channel:
Single voltage gate begins to open at threshold, but is slow--delayed by the same time as the VG Na+ channel’s inactivation gate.