Coord & response Flashcards
function & components of negative feedback loop?
regulate changes in conditions back to set value
input, control centre, effectors (response)
CONTEXT
types of receptors
touch receptor in skin
thermoreceptor in skin
osmoreceptor in hypothalamus
photoreceptors in retina (cones)
feedback loop in context
- receptors in where detect a change in condition above set value
- signal impulses transmitted through nervous system to the hypothalamus, which
- coordinates response of the effectors
central nervous system (neurones)
- receptors detect a stimulus
- triggers nerve IMPULSES from the skin’s touch receptors to the sensory neurone
- then sensory neurones transmit nerve impulses to relay neurones in central nervous system in the spinal cord to motor neurones
- that trigger the response of the effectors (to the cause)
How does structure of glomerulus help in ultrafiltration? (kidney)
- afferent arteriole wider than efferent arteriole
- higher blood pressure in glomerulus
- causes water and small molecules (ions, mineral salts, urea, glucose, amino acids)
- to pass out of glom. TO bowman’s capsule via ULTRAFILTRATION
- while large molecules (red/white blood cells, platelets, proteins)
- are too large to pass thru fine sieve-like structure of glom. walls
- remain in glom.
function of proximal convoluted tubule (+structure, location)
- reabsorption: active transport & diffusion of all glucose and amino acids, most mineral salts into capillary network
- most water reabsorbed by osmosis
big convoluted bundle at start of nephron
function of loop of henle (+structure, location)
water reabsorption from filtrate
U-shape in middle of nephron
formation of urine
glom. bowman+proximal+loop of henle+distal
collecting duct: remaining filtrate (urea, excess water, mineral salts) enter the ureter to form urine
distal convoluted tubule (+structure, location)
selective reabsorption of ions and mineral salts from filtrate
4 types of thermoregulation
Hair erect
- trap still air (poor conductor), reducing heat loss from the skin’s surface via convection/radiation
Sweat
- heat loss from skin’s surface through latent heat of vaporisation via evaporation of sweat
Skin arterioles
- vasodilation/constriction skin surface arteriole, vasodilation/constriction by-pass arteriole
- reduce blood flow to skin’s surface, prevent heat loss
Shivering
- (uncoordinated) contraction and relaxation of skeletal muscle increase heat production
parts of eye
iris, pupil, ciliary body, suspensory ligament, lens, sclera, cornea, retina (fovea), optic nerve (blind spot)
aqueous/vitreous humour
types and properties of photoreceptors
rod: black and white vision in low light conditions
concentrated outside retina
cones: coloured vision in bright light
concentrated in retina
process of seeing an object
- photoreceptors detect light
- transmit nerve impulses via the optic nerve to the brain
- sharp image is formed when light strikes the retina
Why does it take time for our eyes to adjust to darkness?
- visual purple responsible for light sensitivity of rods
- is bleached in bright light
- and takes time to reform to allow sight in low light.
pupil size with muscle contraction/relaxation
pupil dilate: circular relax, radial contract
pupil constrict: circular contract, radial relax
purpose of pupil reflex
-control the amt of light entering the eye such that
- sufficient light enters the eye for clear vision in dim lighting conditions
- and prevent excessive light from entering the eye that may damage photoreceptors in bright light
focusing on near
- ciliary body contract, relax pull on suspensory ligament
- suspensory ligament slackens, relaxing pull on lens
- elastic lens become thicker and more convex
- focal length decreases and light ray from near obj is sharply focused on the retina.
focusing far
- ciliary body relaxes, tightening pull on suspensory ligament
- suspensory ligament becomes taut, tightening pull on lens
- lens becomes thinner and less convex
- focal length increases and light rays from far obj are sharply focused n the retina.
what is homeostasis??
ability to maintain a constant internal environment
shape of sensory, relay and motor neurone
sensory: long with middle nucleus bulb
Relay: extremely short amoeba with nucleus
motor: nucleus bulb at the end
reaction time
additional time is needed for the diffusion of neurotransmitter substances across synapses between sensory and relay, and btwn relay and motor
these take time. (reaction time)
