neurons

Question 1

define neurons

Answer 1

• highly specialized nerve cell > structural, functional unit

Question 2

describe glial tissue

Answer 2

• 40% of brain and spinal cord

- support, protect and provide neurons with nutrition insulate them from each other

Question 3

what determines the function of neurons and what are the 3 types of functional neurons?

Answer 3

• depends on their function
  1. sensory neurons
  2. motorneurons
  3. interneurons

Question 4

what determines the structure of neurons and what are the 3 structures?

Answer 4

• based on the number of extensions from the cell body
  1. bipolar
  2. multipolar
  3. pseudounipolar neurons

Question 5

define nerve fiber

Answer 5

• any long extension of the cytoplasm of a nerve cell body

Question 6

define nerve

Answer 6

• bundles of nerve fibers held together by connective tissue

Question 7

describe the functional types of neurons

Answer 7

sensory neuron

• afferent or receptor neurons
• carry messages from the receptors in the sense organs to the CNS

motor neuron

• efferent or effector neurons
• carry messages from the CNS to the effectors, muscles + glands

interneurons

• association neurons
• located in CNS
• the link between sensory and motor neurons

Question 8

describe the structural types of neurons

Answer 8

multipolar neurons

• one axon
• multiple dendrites
• most common
• includes most interneurons and motor neurons

bipolar neurons

• one axon
• one dendrite
• both may have braches at their ends
• eye ear and nose
• take impulses from the receptor cells to other neurons

psudounipolar neurons
- properties of both unipolar and bipolar neurons
- single axon which separates into two extensions
one connects to dendrites and the other ends in axon terminals
- cell body lies to one side of the main axon
- sensory neurons

Question 9

describe the cell body

Answer 9

• contains the nucleus and is responsible for controlling the functioning of the cell

Question 10

describe dendrites

Answer 10

• short extensions of the cytoplasm of the cell body

often highly branched and they carry messages into the cell body

Question 11

describe the axon

Answer 11

• single, long extensions of the cytoplasm

- carries nerve impulses away from the cell body

Question 12

what are the parts of a neuron (9)

Answer 12

cell body (soma)
dendrites
axon
axon terminals
nodes of Ranvier
schwann cells
myelin sheath
neurilemma
nucleus

Question 13

define Schwann cells

Answer 13

special cells which wrap around the axon and form myelin sheath

Question 14

What are Nodes of Ranvier?

Answer 14

gaps in the myelin sheath

Question 15

what is the neurilemma?

Answer 15

outermost coil of the schwann cell

helps in the repair of injured fibres

Question 16

what does afferent mean

Answer 16

moving towards CNS

sensory neurons

Question 17

what does efferent mean

Answer 17

moving away from CNS

motor neurons