Coordination and response Flashcards
Define homeostasis
maintenance of a stable internal environment in the body
define hormones
A chemical messenger which is made by an endocrine gland. Released in blood and affects target organs
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 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 ADH
hormone produced by the pituitary gland that increases the re absorption of water in the collecting duct of the kidney
define auxin
plant hormone that control cell elongation and plant growth
define CNS
the brain and spinal cord which coordinates the response of effectors
define effectors
muscles or glands which bring about responses
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 geotropism
a plants directional growth in response to gravity controlled by auxin
define insulin
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
define LH
hormone secreted by the pituitary gland that stimulate ovulation and the realease of progesterone
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
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 phototropism
a plants directional growth in response to light
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 receptors
cells that detect a stimulus
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 a stimulus
a change in an organism internal or external environment that can be detected by receptors
what does sweat do
evaporation of water in sweat removes heat energy from the skin, cooling the body down by removing that heat
what is the junction between two nerve cells
synapse, neurotransmitters released to diffuse across
define testosterone
the main male reproductive hormone, produced by the testes, stimulating sperm production and secondary sexual characteristics
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
where are receptor cells located
everywhere
compare a reflex action to a voluntary action
reflex is faster and doesn’t use the brain. Automatic
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 the axon do
electrical impulse travels down it
what does the myelin sheath do
insulates the axon
what is the myelin sheath made out of
fatty substance
what neurones have a myelin sheath
sensory and motor
what neurones have cell body at end
relay and motor
define thyroxine
growth hormone produced in thyroid gland
define insulin
reduces blood glucose after a meal. produced in pancreas
define glucagon
increases blood glucose after a meal. produced in pancreas.
