topic 2: lesson 3

Question 1

neurogila

Answer 1

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

Question 2

neurons

Answer 2

-basic structural and functional unit of the nervous system
-generate electrochemical nerve impulses and carry info from one part of the body to another

Question 3

cell body

Answer 3

contain nucleus, and around the nucleus is the cytoplasm containing other organelles
-mitochondria, ribosomes, etc

Question 4

dendrites

Answer 4

short extensions of the cytoplasm of the cell body

they carry impulses into the cell body

Question 5

axon

Answer 5

single long extension of the cytoplasm
usually carries impulses away from the cell body.

Question 6

myelin sheath

Answer 6

layer of fatty material that covers most axons

axons or nerve fibres are called myelinated or unmyelinated, on the basis of having this sheath or not.

Question 7

Schwann cells

Answer 7

special cells, , outside of the brain and spinal cord which form the myelin sheath. these cells wrap around the axon.

Question 8

nodes of ranvier

Answer 8

the intervals along the nerve fibre where there are gaps in the myelin sheath

Question 9

neurilemma

Answer 9

outer coil of the Schwann cell. it helps in the repair of injured fibres

Question 10

describe how myelin sheath is formed:
(3 points)

Answer 10

-Schwann cell forms the myelin sheath by wrapping around the axon
-they deposit layers of myelin between each coil, was they wrap around
-the outermost coil which is the bulk of the cytoplasm of the Schwann cell is called the neurilemma.

Question 11

3 important functions of the myelin sheath:

Answer 11

1. acts as insulator (prevents the electrical current from leaving the axon)
2. protects the axon from damage
3. it speeds up the movement of impulses along the axon

Question 12

define sensory neuron:

Answer 12

detect stimuli in

Question 13

define motor neurons:

Answer 13

carry messages away from the CNS to the muscles and glands (the effectors)

Question 14

define interneurons:

Answer 14

-located within the CNS, they are the link between the motor and sensory neurons.
-They are able to send and receive messages to or from adjacent neurons.

Most of the neurons in the brain, and many in the spinal cord are this type

Question 15

unipolar neuron structure

Answer 15

1 extension - which connects them to a continuous axon.

Question 16

multipolar neuron structure

Answer 16

Multiple extensions - 1 axon and many dendrites.

Question 17

bipolar neuron

Answer 17

2 extensions – 1 axon and one dendrite (both may branch further later)

Question 18

unipolar neurons more detail

Answer 18

• often called pseudo- unipolar
  -most sensory neurons are this type
  the axon and dendritic fibre are continuous and the cell body is off to one side

one end of the axon is connected to a sense organ (the peripheral side) and the other end is connected to the CNS-usually the spinal cord

dendrites at the peripheral end detect the signal. tend to be longe compared to others.

Question 19

bipolar neurons more detail

Answer 19

they have a distinct axon and a distinct dendritic fibre separated by the cell body.

this type occurs in the eye, ear and nose where they take impulses from receptor cells to other neurons (hence sensory neurons)

Question 20

multipolar neurons more detail

Answer 20

have one axon and many dendrites extending from the cell body

most common type of neuron:
most interneurons- tend to have short axon
all motor neurons - tend to have long axon