Nervous System

Question 1

The Nervous System

Answer 1

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

Question 2

skipped

what homeostatic processes does the NS mediate? (4)

Answer 2

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

Question 3

the NS works along with — to Maintain Systemic

Homeostasis

Answer 3

Endocrine System (ES)

Question 4

NS is — fix to homeostatic disturbance and ES is —

Answer 4

quick

slower long term maintenance

Question 5

NS Functional unit =

Answer 5

Neurons

Question 6

Neuroglia =

Answer 6

support cells for neurons

Question 7

NS uses a combination of (2) to

communicate information around body

Answer 7

chemical and electrical signals

Question 8

dendrites are simulated by (2)

Answer 8

environmental changes or the activities of other cells

Question 9

cell body

Answer 9

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

Question 10

axon

Answer 10

conducts nerve impulse (AP) toward synaptic terminals

Question 11

synaptic terminals affect

Answer 11

another neuron or effector organ (muscle or gland)

Question 12

nissl bodies

Answer 12

clusters of ribosomes found in the cell body

Question 13

Many neurons have axons

that are —

Answer 13

myelinated

Question 14

— formed by neuroglia cells

Answer 14

Internodes

Question 15

– form myelin for axons in CNS

Answer 15

Oligodendrocytes

Question 16

– form myelin for axons in PNS

Answer 16

Schwann cells

Question 17

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

Answer 17

Nodes of Ranvier

Question 18

function of Nodes of Ranvier

Answer 18

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

Question 19

types of neurons (structural classification) (4)

Answer 19

anaxonic
bipolar
pseudo unipolar
multipolar

Question 20

Types of Neurons (Functional Classification) (3)

Answer 20

sensory
motor
interneurons

Question 21

Sensory Neurons (pseudounipolar neurons, bipolar) (4)

Answer 21

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

Question 22

Motor Neurons (Multipolar neurons) (4)

Answer 22

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

Question 23

Interneurons (Multipolar, Anaxonic) (3)

Answer 23

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

Question 24

Information flows in

Answer 24

one direction

Question 25

Action Potentials (AP): (5)

Answer 25

–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

Question 26

Graded Potentials (GP): (3)

Answer 26

–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

Question 27

examples of GP (2)

Answer 27

EPSP

IPSP

Question 28

EPSP

Answer 28

Excitatory postsynaptic potentials (depolarizations); moves Vm
towards threshold potential; increases likelihood of AP

Question 29

IPSP

Answer 29

Inhibitory postsynaptic potentials (hyperpolarizations); moves Vm away
from threshold; decreases likelihood of AP

Question 30

Depolarization

Answer 30

Vm becomes more positive (less

negative). EPSPs

Question 31

Repolarization

Answer 31

Vm returns to resting value

Question 32

Hyperpolarization

Answer 32

Vm becomes more negative than resting. IPSPs

Question 33

Which ion channels, if

opened, cause an EPSP? (2)

Answer 33

Na

Ca

Question 34

Which ion channels cause an IPSP? (2)

Answer 34

K closed

Cl open

Question 35

skipped

Example of a Graded Potential becoming an Action Potential in a Neuron (graph, A-F)

Answer 35

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

Question 36

Activation gate

Answer 36

Closed
at resting Vm, quickly
opens at threshold
depolarization

Question 37

Inactivation gate

Answer 37

Open
at resting Vm, slowly
closes at threshold
depolarization

Question 38

Voltage-gated K+ channel:

Answer 38

Single voltage gate begins to open
at threshold, but is slow–delayed by
the same time as the VG Na+
channel’s inactivation gate.