2 Co-ordination and response Flashcards
How are organisms able to respond to changes in their environment?
external environment: eg avoiding places too hot/cold
internal environment: make sure conditions are always right for their metabolism
Receptors detect stimuli and effectors produce a response
what is negative feedback
a corrective mechanism which responds to a change in conditions from ideal or set point and returns conditions back to set point
Define homeostasis
maintenance of a stable internal environment in the body
What are some examples of homeostasis?
body water content
body temperature
What does a coordinated response require?
stimulus, receptor, effector
What is a stimulus?
change in animal’s surroundings
e.e. ball thrown towards you
What is a receptor?
the organ which detects the change
e.g. eyes
What is an effector?
muscles, e.g. contract as you catch ball
Can plants respond to a stimulus?
yes, e.g. sunlight - will grow towards light
What is a tropism?
the growth of plant towards a directional stimulus
What is phototropism?
growth response to light
growth towards light is called positive phototropism
What controls growth in a phototropic response?
hormone auxin - found tip of stem
What is the role of auxin?
auxin diffuses down shoot from tip causing elongation of cells
when light intensity is higher on one side, auxin builds up on the shaded side
causes cells to elongate more on shaded side
as a result shoot bends towards light
What happens if the tips are cut off or covered?
cut off - no growth
covered - grows directly up
What is geotropism?
growth towards or away fro gravity
roots are positively geotropic
define hormones
A chemical messenger which is made by an endocrine gland. Released in blood and affects target organs
define adrenaline
a hormone produced by the adrenal glands in response to fear or stress. Increase heart rate and boosts the delivery of blood to the muscles, fight or flight response.
define CNS
the brain and spinal cord which coordinates the response of effectors
what does sensory neurone do
Impulses from receptors pass along sensory neurones until they reach the brain and spinal cord
what does relay neurone do
impulses pass to relay neurons in the CNS
what does the motor neurone do
Impulse passes to effectors along motor neurone which causes the effector to contract
define neurotransmitters
chemicals that are released at synapses
what is the reflex arc
a rapid and automatic response to a stimulus
What is the pathway of neurones
stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector, response
what is the junction between two nerve cells
synapse, neurotransmitters released to diffuse across
where are receptor cells located
everywhere
compare a reflex action to a voluntary action
reflex is faster and doesn’t use the brain. Automatic
Compare Endocrine and nervous system
Speed:
E = Slow (except adrenaline), N = Fast
Type of message:
E = Chemical, N = Electrical impulse
Method sent:
E = Via the blood – dissolved in the plasma, N = Along neurones
Response to the message:
E = Only target cells respond even though the message is sent all over the body, N = Message sent directly to a muscle or a gland
Role in body:
E = Controls long term processes such as reproduction and growth, N = Used when a fast response is needed
what does the axon do
electrical impulse travels down it
what does the myelin sheath do
insulates the axon
what neurones have a myelin sheath
sensory and motor
what neurones have cell body at end
relay and motor
what happens in eye in dark light
radial muscles in iris contracts. circular relax. iris causes pupil to dilate to let more light in
what happens in eye in bright light
radial muscles in iris relax. circular contract. iris causes pupil to get smaller to let less light in
what happens in eye when focussing on far away object
suspensory ligaments contract
ciliary muscle relax
lens become long and thin
light focused on retina
what happens in eye when focussing on near object
suspensory ligaments slack
ciliary muscle contract
lens become thick
what type of lens do long and short sighted people require
long: convex lens
short: concave lens
what are the two photoreceptors in retina and what do they do
rods: measure light intensity and send messages along sensory neurone
cones: measure colour and send messages along sensory neurone
what does sweat do
evaporation of water in sweat removes heat energy from the skin, cooling the body down by removing that heat
define vasoconstriction
constriction of blood vessels near the surface of the skin to reduce blood flow near the surface of the skin and therefore reducing the amount of heat that is radiated from the skin
define vasodilation
the dilation of blood vessels near the surface of the skin and increasing the amount of blood flowing near the surface of the skin and so increasing the amount of heat that is radiated from the skin
define thyroxine
growth hormone produced in thyroid gland
define insulin
reduces blood glucose after a meal
hormone secreted by the pancreas when blood glucose concentration is too high, reducing blood glucose concentration by increasing the uptake of glucose from the blood into liver
What is the eye made up of?
Suspensory ligament
cornea
iris
pupil
lens
ciliary muscle
sclera
retina
fovea
optic nerve (sensory neurone)
define adrenaline
a hormone produced by the adrenal glands in response to fear or stress. Increase heart rate and boosts the delivery of blood to the muscles, fight or flight response.
define testosterone
the main male reproductive hormone, produced by the testes, stimulating sperm production and secondary sexual characteristics
define progesterone
a hormone produced in the ovaries, specifically by the corpus luteum and the placenta that maintains the interim lining and inhibits the release of FSH and LH
define oestrogen
a female sex hormone release by the ovaries and stimulate the growth of the uterus lining whilst inhibiting the release of FSH
define ADH
hormone produced by the pituitary gland that increases the re absorption of water in the collecting duct of the kidney
define LH
hormone secreted by the pituitary gland that stimulate ovulation and the realease of progesterone
define FSH
a hormone produced by the pituitary gland that stimulates the growth of follicles in the ovary and stimulates the release of oestrogen
define glucagon
increases blood glucose after a meal. produced in pancreas.
what is the myelin sheath made out of
fatty substance
