Coordination And Response Flashcards
What is a stimulus
A change in an internal or external environment that brings about a response
What are is the CNS
Central nervous system, brain and spinal cord
What are synapses
The connection between two neurons, neurotransmitters diffuse across the gap between them.
What are reflexes
Automatic response to certain stimuli to avoid injury
Describe the reflex arc
Stimulus is detected by receptors which send impulses along a sensory neurone to the CNS. In the CNS, the sensory neurone passes along the message to a relay neurone, the relay neurone relays the impulse to a motor neurone, across a synapse, the impulse then travels to the effector (gland or muscle), which contracts or releases a hormone in response.
What is the conjunctiva
Lubricates and protects the surface of the eye
What is the sclera
Tough outer layer that protects the eye
What does the cornea do
Refracts light into the eye, it has no blood vessels so oxygen diffuses into it from the outer surface
What does the iris do
Controls the diameter of the pupil, and therefore how much light can enter the eye
What does the lens do
Focuses light onto the retina
What are rods and cones
Light receptors
Rods are more sensitive in dim light but can sense colour
Cones are found all over the retina and in the fovea, they detect colour but are not very receptive in dim light
How does the eye respond to bright light
Circular muscles contract, radial muscles relax , reducing pupil size and therefore reducing the light intensity
How does the light focus on distant objects
Ciliary muscles relax which pulls the suspensory ligaments tight, thinning the lens and decreasing refraction
What are hormones
Long lasting chemicals released into the blood and carried by blood plasma
what is the site, role, and effect of adrenaline
adrenal gland, readies body for fight or flight response, and causes and increased heart rate and blood flow to muscles
what is the site, role , and effect of insulin
pancreas, controls blood sugar level, and stimulates liver to turn glucose into glycogen
what is the role, site, and effect of testosterone
testes, male sex hormone, promotes male secondary sexual characteristics
what is the site, role and effect of progesterone
ovary, supports pregnancy, maintains uterus lining
what is the role of oestrogen
female sex hormone, controls menstrual cycle and promotes secondary sexual characteristics
what is the role of ADH
produced in pituitary gland, it increases permeability of kidney tubules to water
what is the role of FSH
causes egg to mature in ovary and stimulates ovary production
what is the role of LH
stimulates release of egg from ovary
what are the differences between hormones and nerves
nerves are faster, short effect and act on a specific area
what is homeostasis
the maintenance of a constant stable internal environment
how is water lost through the body
through the skin as sweat
through the lungs in breath
through the kidney as urine
what colour will your urine be on a hot day
darker, as it is more concentrated
explain what happens to skin when your hot
sweat evaporates from your skin to transfer energy and cause cooling
blood vessels close to surface widen, vasodilate to allow increased blood flow near surface so more energy is transferred to surroundings
hair lies flat ( erector muscles relax)
explain what happens to skin when your cold
very little sweat
vessels near surface vasoconstrict to reduce blood flow near surface
shivering to increase rate of respiration which produces more energy to warm body up
hair stands on end to trap air to act as an insulating layer
why do organisms with larger surface area to volume ratio warm up more quickly
more area for the heat to transfer across
what is auxin
plant growth hormone which controls growth at the tips of shoots and roots, they move through the plant in solution
why do shoots grow towards light
because they are positively phototrophic and auxin accumulates on the shaded side, causing more growth to occur there, bending the plant to the light
why do shoots grow away from gravity
because they are negatively geotropic, auxin accumulates on lower side of tip, causing plant to grow upwards due to bend
why do roots grow towards gravity
positively geotropic, elongation occurs on top causing the root to bend downwards due to extra auxin inhibiting growth
why do roots grow away from light
auxin on shaded side inhibits elongation, so root bends downwards into the ground
