the components of the nervous system

Question 1

what is meant by the term stimulus

Answer 1

a detectable change in the internal or external environment of an organism that produces a response

Question 2

what is meant by the term response

Answer 2

a reaction to a change in stimulus

Question 3

list the main components of the nervous system

Answer 3

1) CNS- comprised of the brain and spinal cord it processes information provided by a stimulus
2) peripheral nervous system- comprised of the somatic nervous system ie processes sensory information and carries info to the CNS , and the automatic nervous system which is responsible for unconscious functions

Question 4

what is the reflex arc

Answer 4

the neural pathway taken by the nervous impulses of a reflex reaction

Question 5

what is a reflex action

Answer 5

a rapid, automatic and unconscious protection response resulting from nervous impulses initiated by a stimulus

Question 6

what are the main components of the spinal cord

Answer 6

1) white matter-
2) grey matter
3) central canal
4) dorsal root
5) ventral root

Question 7

what gives white and grey matter their colour

Answer 7

white- contains nerve fibres surrounded by myelin which is fatty so looks white
grey- contains less myelin and largely made up of nerve fibres and cell bodies

Question 8

what is a nerve net

Answer 8

the simplest form of nervous system formed of a diffuse network of cells that group into ganglia

Question 9

give a good example of an organism with a nerve net and explain its structure

Answer 9

• hydra
• held in the ectoderm ( outer 2 layers of cells of its body wall)
• simple pattern
• ## regenerates easily

Question 10

compare a human nervous system with a nerve net

Answer 10

human- many cells types, regeneration is very slow if at all, myelin sheath present, fast conduction speed, move only in one direction

hydra- 2 cell types, rapid regeneration, no myelin sheath, slow conduction, move in any direction