Co ordination of response Flashcards
(115 cards)
what do receptor cells do
send signals via either the nervous system or the hormonal system to the brain or spinal cord
what is CNS
the brain and spinal cord
what is PNS
all of the nerves in the body
how is information sent through nervous system
in the form of electrical impulses known as neurones
what are hormone/chemical messengers produced by and carried by
chemical substances produced by endocrine glands and carried by the blood
what do hormones do
transmit information from one part of an organism to another and bring about change by altering the activity of one or more specific target organs
why are hormones used to control functions that don’t need instant responses
Hormones are slower in action than nerve impulses
what do endocrine glands do
secrete hormones directly into the blood
how can endocrine glands be stimulated
by the action of another hormone or by the arrival of a nerve impulse
what is found in all types of neurones
axon
axon terminal containing nerve endings
cell body
what is the structure of an axon
long fibre
what does cell body contain
nucleus and other cellular structures
what does nerve ending at the axon terminal allow
neurones to connect to and receive impulses from other neurones, forming a network for easy communication
what does myelinated mean
axon is insulated by a fatty layer known as the myelin sheath
what is a myelin sheath made up of
specialised cells known as Schwann cells which wrap themselves around the axon
what are nodes of ranvier
uninsulated gaps between the Schwann cells
how do electrical impulses moved in myelinated cells
jump from one node to the next, speeding up impulse transmission
in non myelinated neurones is the axon insulated by Schwann cells
no, the impulse travels more slowly as it moves through the entire length of the axon
what does sensory neurone do
carry impulses from receptors to the brain and spinal cord in the CNS
where are relay neurones found
found entirely within the CNS and connect sensory and motor neurones
what do motor neurones do
carry impulses from the CNS to effector muscles or glands
describe structure of motor neurone
A large cell body at one end that lies within the spinal cord or brain
highly-branched dendrites extending from the cell body, providing many connections with the axon terminals of other neurones
structure of relay neurone
Short neurones with axons and highly branched dendrites
structure of sensory neurones
A cell body that branches off in the middle of the axon
The dendrites are attached to a receptor cell
The section of neurone that links the axon terminal with the cell body is known as a dendron
The section of neurone that connects the cell body with the CNS is the axon