nervous system

Question 1

Describe the structure of a neurone

Answer 1

Cell body containing organelles including large amount of rough endoplasmic reticulum to produce neurotransmitter.

Dendrons which subdivide into dendrites and carry impulses towards the cell body

Axon which is a single fibre carrying impulses away from the cell body

Schwann cells surrounding the axon providing protection and electrical insulation

Question 2

what is the role of the cell body

Answer 2

contains all of the organelles associated with the production of proteins and neurotransmitters

Question 3

what is the role of dendrites

Answer 3

carry nerve impulses towards the body

Question 4

what is the role of the myelin sheath

Answer 4

covers axon made up of membrane of schwann cells. rich in a lipid called myelin

Question 5

what type of biological molecule is myelin

Answer 5

lipid

Question 6

what are neurones that have a myelin sheath called

Answer 6

myelinated neuron

Question 7

what is the role of the axon

Answer 7

a single long fibre that carries nerve impulses away from the cell body

Question 8

what is the role of the nodes of ranvier

Answer 8

constrictions between adjacent Schwann cells when there is no myelin sheath. These constrictions are 2-3 um long and occur every 1-3 mm in humans

Question 9

what is the role of Schwann cells

Answer 9

surround axon, protect it and provide insulation. Carry out phagocytosis to remove cell debris and have a role in nerve regeneration. Schwann cells wrap themselves around axon many times so layers of their membrane build up around it

Question 10

what are the name of the cells that make up the myelin sheath

Answer 10

Schwann cells

Question 11

what are 2 principles of coordination

Answer 11

nervous system

hormonal (endocrine) system

Question 12

what is the role of the nervous system

Answer 12

uses nerve cells to pass electrical impulses

stimulate target cells by secreting neurotransmitters

Question 13

what is the role of the hormonal system

Answer 13

produces hormones that are transported in blood plasma to their target cells

slower, less specific communication

Question 14

compare the hormonal system to the nervous system
(8 points for each)

Answer 14

hormonal system
- hormones
- transmitted by bloodstream
- transmission is slow
- hormones travel to all areas of body, only target cells respond
- response is widespread
- response is slow
- response is long lasting
- effect may be permanent and irreversible

nervous system
- nerve impulses
- transmission by neurones
- transmission is very rapid
- nerve impulses travel to specific parts of body
- response is localised
- response is rapid
- response is short lived
- effect is temporary and reversible

Question 15

what is the role of a sensory neurone

Answer 15

transmit nerve impulses from a receptor to an intermediate or motor neurone

Question 16

what type of dendrons and axon does the sensory neuron have

Answer 16

sensory neurone has a long dendron (that carries impulse towards cell body) and one axon (that carries impulse away from cell body)

Question 17

what is the role of the motor neurone

Answer 17

transmit nerve impulses from an intermediate or relay neurone to an effector (e.g: muscle, gland)

Question 18

what type of dendrons and axon does the motor neuron have

Answer 18

long axon and many short dendrites

Question 19

what is the role of the intermediate/relay neurone

Answer 19

transmit impulses between neurones
(from sensory to motor neurone)

Question 20

why does the cell body of neurones contain large amount of RER

Answer 20

production of neurotransmitters (proteins)

Question 21

what type of dendrons and axon does a intermediate/relay neuron have

Answer 21

numerous short dendrites, one short axon

Question 22

Define resting potential

Answer 22

The potential difference across an axon membrane at rest (inside -65mV compared with outside)