unit 14 Flashcards
what do electrical impulses travel through?
electrical impulses travel along
neurones (axon - dendrite)
describe the mammalian nervous system
(a) the central nervous system (CNS) consisting
of the brain and the spinal cord
(b) the peripheral nervous system (PNS)
consisting of the nerves outside of the brain
and spinal cord
what is the role of the nervous system as
coordination and regulation of body functions
Your nervous system’s main function is to send messages from various parts of your body to your brain, and from your brain back out to your body to tell your body what to do - googled
Describe a simple reflex arc
receptor,
sensory neurone, relay neurone, motor neurone
and effector
what is a reflex action?
a means of
automatically and rapidly integrating and
coordinating stimuli with the responses of
effectors (muscles and glands)
what is a synapse
a junction between two
neurones
what is the strcuture of a synapse?
vesicles containing neurotransmitter
molecules, the synaptic gap and receptor
proteins
what happens at a synapse?
a) an impulse stimulates the release of
neurotransmitter molecules from vesicles
into the synaptic gap
(b) the neurotransmitter molecules diffuse
across the gap
(c) neurotransmitter molecules bind with
receptor proteins on the next neurone
(d) an impulse is then stimulated in the next
neurone
what do synapses ensure?
synapses ensure that impulses travel in
one direction only (this si ecause axon terminals contain vesicles, not dendrite)
what are sense organs?
groups of receptor cells responding to specific stimuli
what are the specific stimuli sense organs react to?
light, sound, touch, temperature and chemicals
what is the function of the cornea?
to refract light
what is the function of the iris?
to control how much light enters the pupil
what is the function of the lens?
focuses light on the retina
what is the function of the retina?
contains light receptors, some sensitive to light of different colours
what is the function of the optic nerve?
carries impulses to the brain
what happens in low lighting? (pupil reflex)
Radial muscles contract, so the pupil will appear bigger
what happens in bright lighting? (pupil reflex)
Cordial muscles contract, so the pupil will appear smaller
what does the eye do to view near objects?
ciliary muscle contract. suspensory ligaments slacken. lens becomes fatter.
what does the eye do to view far away objects?
ciliary muscle relaxes. suspensory ligaments contract / stretch thin. lens become thinner.
Describe the distribution of rods and cones in the retina of a human
ummmm?
what is the function of rods?
greater sensitivity for night vision
what is the function of cones?
three different kinds of cones, absorbing light of different colours, for colour vision
what is a hormone?
a chemical substance, producedby a gland and carried by the blood, which alters the activity of one or more specific target organs
what hormones do adrenal glands secrete?
adrenaline
what hormones does the pancreas secrete?
insulin and glucagon
what hormones do the testes secrete?
testosterone
what hormones do the ovaries secrete?
oestrogen
what is adrenaline?
the hormone secreted in ‘fight or flight’ situations
what are the effects of adrenaline?
increased breathing rate, heart rate, pupil diameter, blood glucose concentration
what is the difference between nerve signals and hormones’ signals?
nerve signals are fast through neurons but the effect is short-term. (e.g: dodging a ball. immediate, not needing to be repeated) hormones send signals slowly through bloodstream. (e.g: hips widening) -> meant to stay for years and slowly happen.
