Lecture 25 - Neurons

Question 1

Neurons

Answer 1

Structural units of nervous system

Specialized cells that conduct messages in form of electrical impulses throughout body

Question 2

Special characteristics of neurons

Answer 2

Extrem longevity

Amitotic

High metabolic rate

Question 3

Neuron cell body

Answer 3

Aka perikaryon or soma

Biosynthetic centre of neurons where proteins,membranes and chemicals are synthesized

Question 4

Nissl bodies

Answer 4

Granules of rough endoplasmic reticulum

Question 5

Nuclei

Answer 5

Clusters of neuron cell bodies in CNS

Question 6

Ganglia

Answer 6

Clusters of neuron body cells in PNS

Question 7

Tracts

Answer 7

Bundles of neuron processes in the CNS

CNS contains both neuron cell bodies and their processes

Question 8

Nerves

Answer 8

Bundles of nerve processes in PNS

PNS mostly made up of neuron processes

Question 9

Dendrites

Answer 9

receptive regions of the cell and provide surface area for receiving signals from other neurons

Convey incoming messages toward cell body as GRADED POTENTIALS (short distance signals)

Question 10

Axon

Answer 10

Each neurons has one axon

Some neurons, axons are short or absent
Others axons comprises almost entire .length of cell

Question 11

Axon hillock

Answer 11

Cone shaped area where axon starts

Question 12

Long axons

Answer 12

Nerve fibres

Question 13

Axon branches aka…

Answer 13

Axon collateral

Question 14

Ends of axon (branches)

Answer 14

Axon terminals

Question 15

Axon functions

Answer 15

Conducting region of neuron

Generates nerve impulses and transmits them along axolemma to the axon terminal

Question 16

Axolemma

Answer 16

Neuron cell membrane

Question 17

Axon terminals

Answer 17

Secretory region of cell

Release neurotransmitters that either excite or inhibit other neurons or effector cells

Question 18

Axon transport

Answer 18

Molecules and organelles are moved along axons by motor proteins and cytoskeletal elements

Question 19

Anterograde

Answer 19

Movement away from cell body

Question 20

Retrograde

Answer 20

Movement is towards the cell body

Question 21

Viruses that use retrograde atonal transport

Answer 21

Polio

Rabies

Herpes

Tetanus toxins

Question 22

Multipolar neurons

Answer 22

Most common type of neuron

Three or more processes

Question 23

Bipolar neurons

Answer 23

Have a single axon and dendrite

Located within retina of eye and olfactory mucosa

Question 24

Unipolar

Answer 24

Aka psuedounipolar

Have single T-shaped process

Peripheral process is associated with a sensory receptor and the proximal process enters the CNS

Question 25

Functional class of neurons - sensory

Answer 25

Afferent neuron, conducts impulses TOWARD the CNS from receptors. Almost all are unipolar and cell bodies are located in ganglia in the PNS

Question 26

Functional class of neurons- motor

Answer 26

Efferent neurons, conduct impulses from the CNS to effectors.
Multipolar

Question 27

Functional class of neurons- interneurons

Answer 27

Aka association neurons

Conduct impulses between sensory and motor neurons, or in CNS integration pathways

Most are entirely within CNS

99% of body’s neurons are interneurons