coordination

Question 1

what does coordination involve?

Answer 1

coordination involves the nervous system and the endocrine system

Question 2

how do organisms increase their chance of survival?

Answer 2

organisms increase their chance of survival by responding to changes in their environment

Question 3

how are changes in the environment detected and what does this lead to?

Answer 3

changes in the environment (i.e. stimuli) are detected by receptors and the initiation of nerve impulse leads to a response by effectors by means of a coordinator (usually the brain). the effectors may be muscles or endocrine glands (which secrete hormones).

Question 4

what is the endocrine system?

Answer 4

the endocrine system involves the release of hormones (“chemical messengers”) secreted by endocrine glands. mammalian hormones travel in the bloodstream to target cells affecting their physiological activities. the responses are slow, long-lasting and widespread.

Question 5

in what two distinct mechanisms do hormones act on cells?

Answer 5

peptide hormones e.g. insulin cannot pass through the cell membrane. they have a specific tertiary structure which is complementary to the specific tertiary structure of the protein receptors in the cell membrane to which they bind. this often activates enzyme activity in the cell.

steroid hormones e.g. oestrogen, rapidly pass through the cell membranes as they are lipid soluble.

Question 6

how can the nervous system be divided?

Answer 6

the nervous system can be divided up into the central nervous system (CNS) and the peripheral nervous system (PNS)

Question 7

how can the peripheral nervous system be further divided?

Answer 7

the peripheral nervous system can be further divided into the autonomic and voluntary nervous systems

Question 8

how can the autonomic nervous system be further divided?

Answer 8

the autonomic nervous system can be further divided into the parasympathetic motor system and the sympathetic nervous system

Question 9

what are the three main types of nerve cells (neurons)?

Answer 9

sensory neurones possess receptors which are stimulated by a specific stimulus. an impulse is then transmitted along a sensory neurone to the central nervous system.

motor neurones transmit impulses to the appropriate effector either a muscle or a gland.

relay neurones act as a link between sensory and motor neurones and are situated in the central nervous system. they are also called intermediate or coordinator neurones.

Question 10

what is the structure of a myelinated motor neuron?

Answer 10

see diagram