coordination and response Flashcards
stimuli
changes in the environment that can be detected by organisms
receptors
cells or groups of cells that detect stimuli
may be specialised cells or endings of sensory neurons
effectors
part of the body that respond to a stimulus; muscles and glands
coordination
ensuring that the actions of different parts of the body work together
the way in which the receptors detect stimuli and then pass the info on to the effectors
nerve
a group of neuron axons lying together
used to send information from receptors to effectors
why does there need to be a communication between the receptors and effectors
to make sure you don’t get hurt or for animals that they can quickly catch food.
what makes up the nervouse system
receptors to effectors
neurons
2 ways for sending information from receptors to effectors
nervous system
(slower) hormones, endocrine system
neuron
a cell that is specialised for conducting electrical impulses rapidly
structure of a neuron
same as any animal cell
structure is specially adapted to carrying electrical signals quickly.
>long thin fibres of cytoplasm stretching out of the cell, the longest one is called the axon
>axons can be a meter long,
>shorter fibres called dendrites, pick up electrical signals from other neurons close by. (nerve impulses)
>the signal passes to the cell body, then along the axon, which might pass it to another neurone.
motor neurone
a neurone that transmits electrical impulses from the central nervous system to an effector
axon
a long, thin, fibre of cytoplasm that extends from the cell body of a neurone
dendrites
short fibres of cytoplasm in a neuron
nerve impulses
an electrical signal that passes rapidly along an axon
myelin
axon is wrapped in a layer of fat and protein called myelin.
insulates the nerve fibre, so that they can carry them faster
central nervous system (CNS)
made up of the brain and spinal cord
made up of neurones
its role is to coordinate the electrical impulses traveling through the nervous system
peripheral nervous system (PNS)
made up of nerves spread out from the CNS
includes receptors in our sense organs
what happens when a receptor detects a stimuli
it send an electrical impulse along a neutron to the brain or spinal cord.
they recieve the impulse and send the impulse along the appropiate nerve fibres, to the appropiate effector.
sensory neurone
a neurone that transmits electrical impulses from a receptor to the central nervous system
relay neurone
a neurone that transmits electrical impulses within the CNS
reflex action
the reaction that happens after the impulse has sped around the reflex arc
reflex arc
pathway along in which the nerve impulses passes the sensory neurone, relay neurones and motor neurones. from the receptor to the effector
why are reflex actions useful
bc info moves very quickly without us even thinking abt it.
synapse gap
the gap between each neurone
synapse
the ends of the neuron on either side of the gap + the gap.
the junction between the gap.
vesicle
a very small vacuole
neurotransmitter
a chemical stored in vesicles at the end of neurones, which can be released to diffuse across the synaptic gap and set up an electrical impulse in the next neurone
receptor proteins
proteins on the membrane of the second neurone at a synapse, which have a complementary shape to the molecules of neurotransmitter
sense organ
a group of receptor cells in the retina. these receptor cells are sensitive to light
retina
part of the eye that contains the receptor cells
sensitive to light
tissue at the back of the eye
conjuntiva
thin transparent membrane covering the front of the eye
protects parts behind it
how is the surface of the eye kept moist
by a fluid in the tear glands. contains an enzyme that kills bacteria
when you blink the fluid is washed across your eye.
optic nerve
the nerve that carries electrical impulses from the retina to the brain.
when light falls on the receptor cell in the retina it send an electrical impulse to the optic nerve.
blind spot
part of the retina where he optic nerve leaves and there are no receptor cells
fovea
the part of the retina where the cone cells are very tightly packed; this is where light is focused when you look directly at an object
mostly contains cones
the 2 kinds of receptor cells
rods- sensitive to dim light, dont respond to colour. allow us to see in dim light (black and white), spread out along the retina = less detailed image
cones- can distinguish between colours of light but only function when the light is bright. give us color vision, tightly packed to produce a sharp image
iris
in front of the lens
circular piece of tissue
coloured piece of your eye
contains pigments which absorb lgiht (dont pass through)
in the middle of the iris is the pupil (a gap)
pupil
circular gap in iris
light passes through
size can be adjusted
wider= more light (in dim light)
narrow= less light (in bright light) to not damage retina
how does the pupil adjust size
circular muscles around the pupil
contract= pupil gets smaller
radial muscles run outward from pupil
contract= dilate
iris reflex
an automatic response to a change in lgiht intensity; the receptors are in the retina, and the effector is the muscles in the iris
antagonist muscles
the circular and radial muscles
refraction
bending light rays
so thy focus exactly on the retina
the cornea does this
cornea
a transparent layer near the front of the eye, which refracts light rays entering the eye
lens
a transparent structure in the eye, which changes shape to focus lgiht rays onto the retina
accomodation
changing the shape of the lens to focus on the objects at different distances from the eye
suspensory ligaments
strong inelastic fibres that hold the lens in position; when they are under tension, they pull the lens into a thinner shape
ciliary muscles
a circle of muscle surrounding the lens, and joined to it by the suspensory ligaments; when it contracts, it slackens the ligaments so that the lens becomes fatter
hormones
chemicals that are produced by a gland and carried in the blood, which alter the activites of their specific target organs
secreted in endocrine glands
pass from the gland into the blood plasma.
target organ
organs who’s activity is altered by a hormone
adreneline
hormone secrete by the adrenal glands above the kidneys
prepares your body for flight of fight
adrenalines effect
heart beats faster > more quickly oxygen to your brain and muscles
>muscles to carry out aerobic respiration more quickly, more energy for running
breathing rate increase> more oxygen to lungs
pupils to dilate> more light> see more
liver to release more glucose into the blood> for muscles > metabolic activity increases
how do plants react to stimuli
by changing their growth towards or away from stimuli
tropism
a growth response by a plant; on which the direction of growth is related to the direction of the stimulus
phototrpopsim
a response in which a part of a plant grows towards or away from the direction from which the light is coming
gravitropism
a response in which part of a plant grows towards or away from gravity
shoots grow have negative gravitropism, roots the oppisite
auxin
a plant hormone made in the tips of shoots, which causes cells to elongate
