Week 1 CNS Organization: Objectives 1-2

Question 1

Anatomical Organization of the Nervous System (3 pts)

Answer 1

CNS: brain and spinal cord
PNS: Cranial nerves and spinal nerves
ANS: Sympathetic and Parasympathetic

Question 2

What structure does the nervous system directly arise out of?

Answer 2

the neural tube

Question 3

the brain possess how many cranial nerves, and how many parasympathetic fibers?

Answer 3

12 cranial nerves, 4 of which are parasympathetic (III, VII, IX, X)

Question 4

General functional categories of the brain

Answer 4

Sensory, motor, cognitive

Question 5

Spinal Cord, 3 small details

Answer 5

1. spinal cord first structure encountered by most incoming sensroy information except in cranial nerves
2. spinal cord is the last relay station for most motor information except ANS motor fibers
3. Spinal cord is the site of coordination of most reflex arcs

Question 6

Afferent/Efferent pathways

Answer 6

PNS

Afferent (sensory) pathways
Efferent (motor) pathways

Question 7

ANS (overview)

Answer 7

Subdivision of PNS
entirely motor
innervates smooth muscle and glands (viscera)

Question 8

ANS (subdivisions)

Answer 8

Sympathetic: Fight or flight
Also called thoracolumbar

Parasympathetic: Feed and breed
also called carniosacral

Question 9

Parasympathetic system

Answer 9

feed or breed

Also called craniosacral

Question 10

Cell body is called (something weird) _____

Answer 10

trophic unit

perikaryon

Question 11

Dendrites

Answer 11

receptive unit

Question 12

Axon

Answer 12

conductive unit

Question 13

Dendrites…..definition and description

Answer 13

branches off cell body, carries information to the cell body

has several to many dendrites per neuron
relatively short, especially compared to the axon
often branched
have receptors for neurotransmitters
conduct local potentials

Question 14

Axons….D & D

Answer 14

part of neuron that carries signal
relatively long
single, one per neuron 
conducts action potential 
release neurotransmitters 

ENDS with telodendria
have “Collateral branches”

has mitochondria, neurofilaments and neurotubules

Question 15

telodendria

Answer 15

give off endings called terminal boutons

terminal boutons contain synaptic vesicles filled with neurotransmitters

Question 16

Axoplasm vs Axolemma

Answer 16

axolemma = axon membrane 
axoplasma = cystoplam of an axon

Question 17

Axon is covered by a

Answer 17

neurolemma

Question 18

neurolemma is made of

Answer 18

schwann cells

Question 19

the neurolemma is often

Answer 19

myelinated

Question 20

TRUE/FALSE all Schwann cells indicated axon is myelinated

Answer 20

false

Question 21

Nucleus/Ganglion/Nerve/Tract/Commissure/White matter/Gray matter

Answer 21

Nucleus = aggregation of dendrites and nerve cell bodies in CNS

Ganglion = aggregation of dendrites and nerve cell bodies in the PNS

Nerve: bundle of fibers (axons) in the PNS

Tract: bundle of fibers (axons) in the CNS

Commissure = tract in the CNS that crosses from one side to the other

White matter = areas of myelinated axons

Gray matter = unmyelinated axons, cell bodies, dendrites

Question 22

PNS system includes

Answer 22

12 cranial nerves
31 spinal nerves

Sensory receptors in the skin, wall of gut tube, tendons in skeletal muscles

motor end plates between motor neurons and skeletal muscle fibers

Question 23

Spinal nerve branches

Answer 23

spinal nerves divide into two major branches (rami)

Question 24

each spinal nerve in the thoracolumbar region, before branching into primary rami, gives off

Answer 24

two small branches:

white ramus communicans (carries myelinated preganglionic fibers)

gray ramus (carries unmyelinated postganglionic fibers back to spinal nerve)

Question 25

Paravertebral ganglia (3 things))

Answer 25

linked together in long chain on either side of the vertebral column site of cell bodies of postganglionic sympathetic nerves site of synapses between preganglionic myelinated sympathetic neurons and non myelinated sympathetic neurons

Question 26

Splanchnic nerve

Answer 26

nerve supplying viscera

Question 27

Preverterbral ganglion

Answer 27

typically anterior to abdominal aorta site of synapses between preganglionic myelinated sympathetic neurons and postganglionic non-myelinated neurons

Question 28

Reflex arc

Answer 28

path that leaves from and returns to the central nervous syste,. consists minimally of sensory pathway and a motor pathway somatic afferent pathways carry sensation from non-visceral structure such as the skin and skeletal muscle

Question 29

Somatic afferent pathways carry sensation from

Answer 29

non-visceral structures such as the skin and skeletal muscle

Question 30

Splanchnic afferent pathways carry sensations from

Answer 30

viscera

Question 31

Efferent (motor) pathways: Somatic and Visceral

Answer 31

Somatic efferent pathways carry motor signals to skeletal muscles Visceral efferent pathways carry motor signal to smooth or cardiac muscles (also called visceral motor pathways)

Question 32

Somatic efferent pathways carry

Answer 32

motor signals to skeletal muscles

Question 33

Visceral motor pathways carry

Answer 33

motor signal to smooth or cardiac muscles

Question 34

Thoracolumbar

Answer 34

Fight or flight sympathetic

Question 35

Craniosacral

Answer 35

Feed and breed, parasympathetic

Question 36

Somatic Afferent Pathways Visceral Afferent Pathways Somatic Efferent Pathways Visceral Efferent Pathways

Answer 36

Somatic Afferent (sensory, to the brain) Pathways: carry sensory information from non-visceral regions like skin and skeletal muscle to the brain Visceral Afferent (sensory, to the brain) Pathways carry sensations from viscera to the brain Somatic Efferent (motor, to target region) Pathways: carry motor signals to skeletal muscles Visceral Efferent pathways (Visceral motor pathways): carry motor signals to smooth or cardiac muscles

Question 37

Association Neuron

Answer 37

interneuron Most reflex arc consist of a afferent and efferent neuron with an interneuron in the CNS to modulate their interactions, some don't.

Question 38

Components of a Synapse

Answer 38

Presynaptic membrane (associatied with synaptic vesicles filled with neurotransmitters) synaptic cleft postsynaptic membrane (associated with receptors for neurotransmitters)

Question 39

Monosynaptic pathway

Answer 39

Pathways consisting only of afferent neurons and efferent neurons. Each pathway has only one synapse

Question 40

Polysynaptic pathways

Answer 40

Pathways that include interneurons as well as afferent and efferent neurons. Each pathway has multiple synapses

Question 41

Secondary messenger system

Answer 41

Transmitter-- >receptor protein --> G protein --> G protein opens channel, activates one or more intracellular enzymes (with corresponding chemical reactions), activates gene transcription (proteins and structural changes), activates enzyme that converts ATP to cAMP or GTP to cGMP

Question 42

Physiological States of a Neuron: Resting, Excited, Inhibited

Answer 42

``` Resting = -65 mV Excited = -45 mV Inhibited = -70 mV (due to influx of chloride or efflux of potassium) ```

Question 43

Extracellular concentrations of N, K and Cl

Answer 43

``` Na = 142 mEg/L K = 4.5 MEg/L Cl = 107 mEq/L ```

Question 44

Intracellular concentrations of Na, K, Cl

Answer 44

``` Na = 12 mEq/L K = 120 mEq/L Cl = 8 mEq/L ```

Question 45

Excitatory Postsynaptic Potentials (2)

Answer 45

Simultaneous firing of a few synapses will not summate to produce an action potential on a postsynaptic neuron superimposed action potential can be caused by the simultaneous firing of many synapses on the postsynaptic neuron

Question 46

8-4 synapses firing at once will produce

Answer 46

not enough potential to cause an action potential

Question 47

Somatosensory Axis

Answer 47

refers to the sequence of events leading to the firing of a signal from the peripheral to the higher brain centers

Question 48

Somatosensory Axis Components

Answer 48

Peripheral receptors ---> Afferent neurons ---> spinal cord or brainstem ---> Reticular substance (medulla, pons, mesencephalon) ---> cerebellum ---> thalamus ---> somesthetic areas of cerebral cortex

Question 49

Somatosensory Axis: Afferent Neurons

Answer 49

Arranged in a series of three 1. Primary Afferent synapses in the posterior horn of the spinal cord or sensory nuclei 2. Secondary Afferent Synapses in the thalamus 3. Tertiary Afferent synapses in the somesthetic areas of cerebral cortex

Question 50

Skeletal Motor Nerve Axis

Answer 50

Skeletal motor nerve Axis refers to the sequence of structures involved in the transmission of an action potential from the higher functions of the brain to the skeletal muscle

Question 51

Skeletal motor nerve axis: origin of action potential

Answer 51

Motor cortex of cerebrum

Question 52

Efferent pathways of the Skeletal Motor Nerve Axis + "effectors"

Answer 52

upper motor neurons extending from cortical areas to the anterior horns of the spinal cord alpha motor neurons (lower motor neurons) extending to the skeletal muscles effector = skeletal muscles smooth muscle and glands are taken care of by ANS, and have a different pattern.

Question 53

Skeletal motor nerve axis: processing areas of the skeletal motor nerve axis

Answer 53

1. Basal ganglia a. putamen b. Globus pallidus c. Subthalamic nuclei Thalamus in the diencephalon Spinal cord reflexes