Test 3

Question 1

what are the 3 main functions of the Nervous system

Answer 1

1. Sensory input: uses sensory receptors to monitor changes(stimuli) inside and outside the body
2. Integration: interprets the sensory input and decides what to do
3. Motor output: Dictates a response to the changes by activating the effector organs

Question 2

Basic divisions of the NS

Answer 2

Central NS: brain and spinal cord

Peripheral NS: nerves and ganglia

• > Cranial nerves: carry info to and from brain
• > spinal nerves :carry info to and from spinal cord
• > Ganglia: areas where the cell bodies of neurons are clustered

Question 3

first two divisions of the Motor(efferent) division of the peripheral NS

Answer 3

1. Somatic NS: somatic motor (Voluntary)- Conducts nerve impulses from CNS to structures external to the ventral body cavity (skin, skeletal muscle, bones)
2. Automatic NS:
   Visceral motor (Involuntary)- conducts impulses from CNS to visceral body region(digestive tube, lungs, heart, bladder) >sympathetic&parasympathetic divisions

Question 4

4 main subdivisions of PNS

Answer 4

1. Somatic sensory
2. Visceral sensory
3. Somatic motor (to skeletal muscle)
4. Visceral motor (autonomic NS- cardiac/smooth muscle and glands)

Question 5

1. Somatic sensory

Answer 5

• General: touch, pain, pressure, vibration, proprioception from skin/body wall/limbs
• special: hearing, equilibrium and vision

Question 6

2. Visceral sensory

Answer 6

• General: stretch, pain, temp, chemical changes and irritation in the viscera; nausea and hunger
• special: taste and smell

Question 7

nervous tissue cell types

Answer 7

1. neurons: excitable nerve cells that transmit electrical signals
2. neuroglia: nonexcitable supporting cells that surround and wrap the neurons

Question 8

neuron functional characteristics

Answer 8

• conduct electrical signals in form of nerve impulses or APs
• extreme longevity
• no mitosis
• high metabolic rate

Question 9

Cell body

Answer 9

aka the soma

• normal organelles and chromatophillic substance (large clusters of rough ER and free ribosomes that stain darkly)
• neurofibrils: bundles of intermediate filaments that run in a network b/w the chromatopillic subsstance
• most cell bodies within the CNS, some within ganglion in the PNS

Question 10

Dendrites

Answer 10

• each has all the normal organelles and chromatophillic substance
• receptive sites for signals, carried to cell body

Question 11

Axon

Answer 11

only one per neuron

• arises from region of cell body called axon hillock (region of impulse generators and conductors)
• no organelles for protein synthesis , must get proteins from neurofilaments, actin microfilaments and microtubules which carry substances

Question 12

what three things stem from or come off the axon

Answer 12

axon collaterals: branches that extend from the axon at right angles
terminal aborization: branchess at the end of the axon
terminal boutons: the ends of terminal aborizations

Question 13

what are axodendritic synapses and axosomatic synapses

Answer 13

axodendritic: occur b/w one neuron and dendrite of another neuron
axosomatic: occur b/w axons and neuron cell bodies

Question 14

multipolar, bipolar and unipolar

Answer 14

multipolar: more than 2 processes coming off cell body (most abundant- many in CNS)
Bipolar: 2 processes that extend from either side of the cell body (rare)
-Unipolar: short, single process that emerges from the cell body and divides like an inverted T into teo long branches (mostly in PNS, ex. dorsal root ganglion cell)

Question 15

sensory vs. motor vs. interneurons

Answer 15

sensory: most are pseudounipolar or with cell bodies in ganglia outside the CNS or bipolar and located in sense organs(retina)
motor: multipolar with cell bodies in the CNS
Interneurons: B/w motor and sensory neurons and confined to CNS, most multipolar neurons are interneurons

Question 16

Neuroglia in the CNS

Answer 16

1. Astrocytes
2. Microglial cells:
3. Ependymal cells:
4. Oligodendrocytes:

Question 17

1. Astrocytes

Answer 17

1. Astrocytes: star shaped, most abundant, regulate NT levels, signalling increased blood flow through capillaries in active regions of the brain and controlling the ionic environment around the neurons

Question 18

2. Microglial cells:

Answer 18

smallest, least abundant, elongated cell bodies and cell processes with many pointed projections, phagocytic

Question 19

3. Ependymal cells:

Answer 19

single epithelium that lines the central cavity of the spinal cord and brain(BBB), move CSF

Question 20

4.Oligodendrocytes:

Answer 20

line up in small groups and wrap their cell processes around thicker axons in the CNS producing insulating covering called myelin sheath

Question 21

Neuroglia of PNS

Answer 21

1. satellite cells: surround neuron cell bodies within the ganglia
2. Schwann cells: surround all axons in the PNS forming myelin sheath

Question 22

Myelination process in PNS:

Answer 22

1. schwann cell envelopes the axon
2. the schwann cell rotates around the axon, wrapping its plasma membrane loosely around it in successive layers
3. the schwann cell cytoplasm is forced from b/w the membranes. the tight membrane wrappings surrounding the axon form the myelin sheath

Question 23

Grey vs white matter of the CNS

Answer 23

1. Grey matter:
   - surrounds the hollow central cavity of the CNS
   - site where neuron cell bodies are clustered (of inter and motor neurons)
   - synapses occur here
   - in the cerebrum and cerebellum there are additional superficial layers of grey matter forming a cortex
2. White matter:
   - no cell bodies, but many axons and neuroglia
   - white in color is from the myelinated axons
   - axons traveling to similar destinations are called tracts

Question 24

what does a nerve consist of

Answer 24

many fascicles which each fascicle containing many axons

• Epineurium: tough fibrous sheath that surrounds the entire nerve
• perineurium: wraps around a nerve fascicle
• endoneurium: layer of loose connective tissue covering schwann cells

Question 25

describe neuronal integration

Answer 25

- communication b/w CNS and PNS - sensory nerves send signals to spinal cord, moter nerves send signals out to the body - integrated in the grey matter

Question 26

what is a reflex arc

Answer 26

simple chains of neurons that cause our simplest, reflexive behaviours and reflect the basic structural plan of the NS

Question 27

5 essential components of the reflex arc

Answer 27

1. receptor 2. sensory neuron 3. integration centre 4. motor neuron 5. effector

Question 28

what are the three neuronal circuits?

Answer 28

1. diverging circuit 2. converging circuit 3. reverberating circuit

Question 29

1. diverging circuit

Answer 29

info is distributed through many neuronal pathways

Question 30

2. converging circuit

Answer 30

signals are integrated and influence whether or not it will initiate a nerve impulse

Question 31

3. reverberating circuit

Answer 31

involved in control of rhythmic activities | ex. breathing, swinging of leg during walking

Question 32

Serial neural processing

Answer 32

- neurons that synapse in a one-on-one sequence of a signal pathway - neurons joined in series - single pathway ex. reflex arc

Question 33

parallel neural processing

Answer 33

- info from a single neuron is sent along two or more parallel pathways - multiple signals are integrated