15.1- NEURONES AND NERVOUS COORDINATION

Question 1

What have cells lost as they have specialised in one fiunction?

Answer 1

ability to perform other functions

Question 2

As cells become specialised and lose their ability to perform other functions, what do they do?

Answer 2

depend upon others to carry out functions they no longer specialise in

Question 3

What are the two main forms of coordination in animals as a whole?

Answer 3

the nervous system and the hormonal system

Question 4

What does the nervous system use to pass electrical impulses along their length?

Answer 4

nerve cells

Question 5

How does the nervous system stimulate their target cells?

Answer 5

by secreting chemicals called neurotransmitters directly on them

Question 6

What does neurotransmitters being secreted directly on to target cells result in? (nervous system)

Answer 6

rapid communication between specific parts of organism

Question 7

What are the responses produced by the nervous system described as?

Answer 7

short-lived + restricted to localised region of body

Question 8

What does the hormonal system produce and where it transported through to?

Answer 8

produced chemicals (hormones) that are transported in blood plasma to target cells

Question 9

What do the target cells have and what stimulates them? (hormonal system)

Answer 9

specific receptors on their cell-surface membranes + change in conc. of hormones stimulate them

Question 10

What sort of communication does the hormonal system produce?

Answer 10

slower, less specific form of communication between parts of organism

Question 11

What are the responses produced by the hormonal system described as?

Answer 11

long-lasting + widespread

Question 12

What are neurones adapted to do?

Answer 12

rapidly carry electrochemical changes called nerve impulses from one part of body to another

Question 13

What is a mammalian motor neurone made up of? (6)

Answer 13

cell body
dendrons
axon
Schwann cells 
myelin sheath
nodes of Ranvier

Question 14

What does the cell body of a mammalian motor neurone contain?

Answer 14

all the usual cell organelles, including a nucleus + large amounts of rough ER

Question 15

What is the cell body of a mammalian motor neurone associated with?

Answer 15

production of proteins + neurotransmitters

Question 16

What are the dendrons of a mammalian motor neruone?

Answer 16

extensions of cell body which divide into smaller branched fibres, called dendrites, that carry nerve impulses towards cell body

Question 17

What is an axon of a mammalian motor neurone?

Answer 17

single long fibre that carries nerve impulses away from cell body

Question 18

What do the Schwann cells of a mammalian motor neurone surround?

Answer 18

axon

Question 19

What do the Schwann cells of a mammalian motor neurone do?

Answer 19

protect axon + provide electrical insulation

Question 20

What process do the Schwann cells of a mammalian motor neurone carry out and what is it apart of?

Answer 20

phagocytosis

play role in nerve regeneration

Question 21

How are the Schwann cells of a mammalian motor neurone organised?

Answer 21

Schwann cells wrap themselves around axon many times, so that layers of their membranes build up around it

Question 22

What does the myelin sheath of a mammalian motor neurone form?

Answer 22

covering to axon

Question 23

What is the myelin sheath of a mammalian motor neurone made up of?

Answer 23

membranes of Schwann cells

Question 24

What are the membranes of the Schwann cells rich in?

Answer 24

lipid known as myelin

Question 25

What are neurones with a myelin sheath called?

Answer 25

myelinated neurones

Question 26

What are nodes of Ranvier of a mammalian motor neurone?

Answer 26

constrictions between adjacent Schwann cells where there's no myelin sheath

Question 27

How long are the nodes of Ranvier (constrictions)?

Answer 27

2-3µm long

Question 28

How often do the nodes of Ranvier (constrictions) occur on humans?

Answer 28

every 1-3mm

Question 29

How can neurones be classified?

Answer 29

according to their function

Question 30

What are the different types of neurones? (3)

Answer 30

sensory neurones motor neurones intermediate or relay neurones

Question 31

What do sensory neurones do?

Answer 31

transmit nerve impulses from receptor to intermediate/ motor neurone

Question 32

How many dendrons does a sensory neurone have and how can it be described as?

Answer 32

one dendron that's often very long

Question 33

Where does the sensory neurone carry the impulse towards?

Answer 33

towards cell body + one axon that carries it away from cell body

Question 34

What do motor neurones do?

Answer 34

transmit nerve impulses from intermediate/ relay neurone to effector, such as gland or muscle

Question 35

What are the axons and dendrites of motor neurones described as?

Answer 35

long axon and many short dendrites

Question 36

What do intermediate or relay neurones do?

Answer 36

transmit impulses between neurones e.g. from sensory to motor neurones