module 5 - 13.2 neurones

Question 1

what is a neurone/nerve cell?

Answer 1

a cell that transmits electrical impulses and communicates with other cells c=via specialised connections called synapses

Question 2

what is the main component of nervous tissue in all animals (except sponges)

Answer 2

a neurone
- plants and fungi do not have neurones

Question 3

what are the 3 types of neurones?

Answer 3

sensory neurone
relay neurone
motor neurone

Question 4

what is the function of neurones?

Answer 4

to rapidly transmit electrical impulses to allow coordination

Question 5

what is the cell body of a neurone?

Answer 5

nucleus, mitochondria and RER to allow protein synthesis, production of neurotransmitters

Question 6

what are the dendrons of a neurone?

Answer 6

transmits electrical impulses TOWARDS cell body, form a branching pattern with smaller dendrites

Question 7

what is the axon of a neurone?

Answer 7

transmits electrical impulses AWAY from the cell body, often very long, narrow cytoplasm covered by plasma membrane with microtubule support

Question 8

what is nerve tissue?

Answer 8

a large bundle of neurones

Question 9

what is a sensory neurone?

Answer 9

• transmits electrical impulses from receptor cell to brain or motor neurone
• dont detect stimulus
• have one dendron that may branch into several dendrites
• dendron carried impulse to cell body
• axon carried impulse away from cell body

Question 10

what is a relay neurone?

Answer 10

• transmits electrical impulses between neurones
• has central cell body
• has many short dendrons branching into several dendrites
• dendrons/dendrites carry nerve impulses towards cell body
• many axons that branch our
• axons carry impulses away from cell body

Question 11

what are motor neurones?

Answer 11

• transmit electrical impulses from relay neurone or sensory neurone to an effector
• has many dendrites that carry the impulse towards cell body
• long axon, may have branches at its terminal
• axon carries impulse away from cell body

Question 12

what are effectors?

Answer 12

muscles or glands

Question 13

what are myelinated neurones?

Answer 13

neurones that have an insulating layer around the axon made from myelin

Question 14

what is myelin made by when in the PNS?

Answer 14

schwann cells when a neurone is in the peripheral nervous system (PNS)

Question 15

what is myelin made by when in the CNS?

Answer 15

oligodendrocytes when the neurone is in the central nervous system (CNS)

Question 16

what are schwann cells?

Answer 16

• produce many layers of plasma membrane by growing around and around the axon of neurones in the PNS (lipid based myelin sheath)
• outer layer of schwann cells is called neurilemma

Question 17

what is the role of a schwann cell?

Answer 17

allows dead neurones to reform inside the tunnel created by the schwann cell (band of bunger)

Question 18

what are oligodendrocytes?

Answer 18

• perform same function as schwann cells bu =t are found on neurones of the CNS
• do not have neurilemma as they wrap around multiple axons (up to 50)

Question 19

what is the myslin sheath made from?

Answer 19

schwann cells

Question 20

what are the nodes of Ranvier?

Answer 20

small gaps between the myelin sheath and where the axolemma is exposed to extracellular space

Question 21

ow?what do the nodes of ranvier allw

Answer 21

allows electrical impulse to jump from one node to the next, increasing speed of transmission of impulse
- THIS IS CALLED SALTATORY CONDUCTION

Question 22

what is the charcot-marie-tooth disease?

Answer 22

• group of inherited disorder of nerves
• characterised by loss of muscle tissue and touch sensation
• incurable
• one of the most common inherited neurological disorders

Question 23

what is multiple sclerosis?

Answer 23

• demyelinating disease where myselin sheath of nerve cell axons in the brain and spinal cord are damaged
• damage disrupts ability of parts of nervous system to transmit signals
• results in physical, mental and psychiatric problems
• underlying mechanism is either destruction of immune system or failure of myelin producing cells
• incurable