Coord & response

Question 1

function & components of negative feedback loop?

Answer 1

regulate changes in conditions back to set value

input, control centre, effectors (response)
CONTEXT

Question 2

types of receptors

Answer 2

touch receptor in skin
thermoreceptor in skin
osmoreceptor in hypothalamus
photoreceptors in retina (cones)

Question 3

feedback loop in context

Answer 3

• 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

Question 4

central nervous system (neurones)

Answer 4

• 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)

Question 5

How does structure of glomerulus help in ultrafiltration? (kidney)

Answer 5

• 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.

Question 6

function of proximal convoluted tubule (+structure, location)

Answer 6

• 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

Question 7

function of loop of henle (+structure, location)

Answer 7

water reabsorption from filtrate

U-shape in middle of nephron

Question 8

formation of urine

Answer 8

glom. bowman+proximal+loop of henle+distal

collecting duct: remaining filtrate (urea, excess water, mineral salts) enter the ureter to form urine

Question 9

distal convoluted tubule (+structure, location)

Answer 9

selective reabsorption of ions and mineral salts from filtrate

Question 10

4 types of thermoregulation

Answer 10

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

Question 11

parts of eye

Answer 11

iris, pupil, ciliary body, suspensory ligament, lens, sclera, cornea, retina (fovea), optic nerve (blind spot)

aqueous/vitreous humour

Question 12

types and properties of photoreceptors

Answer 12

rod: black and white vision in low light conditions
concentrated outside retina

cones: coloured vision in bright light
concentrated in retina

Question 13

process of seeing an object

Answer 13

• photoreceptors detect light
• transmit nerve impulses via the optic nerve to the brain
• sharp image is formed when light strikes the retina

Question 14

Why does it take time for our eyes to adjust to darkness?

Answer 14

• visual purple responsible for light sensitivity of rods
• is bleached in bright light
• and takes time to reform to allow sight in low light.

Question 15

pupil size with muscle contraction/relaxation

Answer 15

pupil dilate: circular relax, radial contract

pupil constrict: circular contract, radial relax

Question 16

purpose of pupil reflex

Answer 16

-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

Question 17

focusing on near

Answer 17

• 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.

Question 18

focusing far

Answer 18

• 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.

Question 19

what is homeostasis??

Answer 19

ability to maintain a constant internal environment

Question 20

shape of sensory, relay and motor neurone

Answer 20

sensory: long with middle nucleus bulb
Relay: extremely short amoeba with nucleus
motor: nucleus bulb at the end

Question 21

reaction time

Answer 21

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)