nervous system

Question 1

How sensory neurone looks like

Answer 1

Sensory neurone:

–i–

Question 2

how relay neurone looks like

Answer 2

relay neurone:

–o—

Question 3

how motor neurone looks like

Answer 3

motor neurone:

0——

Question 4

function of sensory neurones

Answer 4

to transmit impulses from receptors to spinal cord or brain (central nervous system)

Question 5

function of relay neurones

Answer 5

to relay impulses from sensory neurones to motor neurones

Question 6

function of motor neurones

Answer 6

to transmit impulses from the central nervous system to effector organs such as muscles and glands

Question 7

the function of the brain and spinal cord in producing a coordinated response as a result of a specific stimulus in a reflex action.

Answer 7

1) the action begins when the receptors on a sense organ detect a stimulus, which is a form of energy such as sound, light or mechanical pressure.
2) This may become an impulse transmitted by a sensory neurone that serves that sense cell to the spinal cord

3) Once generated, the impulse is transmitted along dendrons and axons of a sequence of neurones of the reflex arc to an effector organ:
- –> in the spinal cord/brain, the nerve impulses are transmitted first across a synapse to relay neurone and then across another synapse to the motor neurone
- –>the motor neurone transmits the impulses from the spinal cord to the effector

4) when it arrives at the effector, the impulse causes a response e.g. it may cause a muscle to contract or a gland to secrete
stimulus → receptor → sensory neurone →1st synapse -→ relay neurone → 2nd synapse → motor neurone → effector

Question 8

difference btw endocrine and nervous system

Answer 8

Endocrine system: communication by chemical messengers (hormones) transmitted in the bloodstream
Nervous system: communication by electrochemical action potentials (nerve impulses) transmitted via neurones

Endocrine system: hormones ‘broadcast’ all over the body but influence target cells and tissues only (> one target organ)
Nervous system: action potentials are targeted on specific cells (usually localised)

Endocrine system: causes changes in metabolic activity
Nervous system: causes muscles to contract or glands to secrete

Endocrine system: have their effects over many minutes, several hours or longer
Nervous system: produces effects within milliseconds

Endocrine system: effects tend to be long lasting (e.g. growth hormone → puberty
Nervous system: effects tend to be short-lived and reversible