B10 The human nervous system

Question 1

what is homeostasis

Answer 1

regulation of internal conditions of cells to maintain optimum conditions for functioning, in response to internal and external changes

Question 2

internal conditions that are controlled

Answer 2

body temp
water content of body
blood glucose concentration

Question 3

receptors

Answer 3

cells that detect changes in internal/ external environment (known as stimuli)

Question 4

coordination centres

Answer 4

areas that receive and process the information from the receptors
send out signals to coordinate the response of the body

Question 5

coordination centres examples

Answer 5

brain- for nervous system and parts of hormonal system
spinal cord
pancreas

Question 6

effectors

Answer 6

muscles or glands that bring about responses to the stimulus that has been received - they restore conditions in body to optimum

Question 7

how nervous system works

Answer 7

sensory receptor detects stimulus, electrical impulses pass along neurones until it reaches central nervous system, motor neurones carry info from CNS to rest of body and effectors respond

Question 8

reflexes

Answer 8

automatic responses to stimuli
important to avoid danger/ harm and take care of basic body functions (breathing, digestive system)
do NOT involve conscious part of brain

Question 9

how do reflexes work

Answer 9

involve sensory, motor and relay neurones
electrical impulse passes from receptor along s neurone to cns
then along relay neurone (usu. spinal cord) and then back along m neurone
impulse arrives at effector organ (muscle or gland)
pathway known as REFLEX ARC

Question 10

role of synapse

Answer 10

electrical impulse travelling along neurones have to cross these synapses
diffusion of chemical across synapse is slower than the electrical impulse in neurones

Question 11

what are synapses

Answer 11

junctions between neurones which form physical gaps between them

Question 12

cerebral cortex

Answer 12

concerned w consciousness, intelligence, memory and language

Question 13

cerebellum

Answer 13

concerned mainly w coordinating muscular activity and balance

Question 14

medulla

Answer 14

unconscious activities
eg heartbeat, movements of gut and breathing

Question 15

hypothalamus

Answer 15

controls body temp

Question 16

pituitary gland

Answer 16

produces many hormones which contribute to coordinating controlling body systems

Question 17

structure of eye

Answer 17

sclera- outer layer
muscular iris- controls size of pupil
pupil- whole through which light enters
lens- held in place by suspensory ligaments and ciliary muscles
retina- when light hits, light sensitive cells are stimulated

Question 18

focusing the light

Answer 18

light focused on light sensitive cells of retina
focused through refraction
light rays made to change direction
will always be refracted same amount

Question 19

focusing distant

Answer 19

distant- ciliary muscles relax so suspensory ligaments are pulled tight and lens is flat and thin

Question 20

focusing close

Answer 20

ciliary muscles contract so suspensory ligaments loosen, lens is then thicker and more curved

Question 21

myopia

Answer 21

short sightedness
may be result of lens that is too curves/ partially long eyeball
treatment- wear glasses with concave lens to spread out light from distant objects

Question 22

hyperopia

Answer 22

long sightedness
may be a result of too flat/ thin lens
lens cannot refract the rays of light strongly enough so light is focused behind retina
glasses w convex lens to bring rays together more closely