Nervous System

Question 1

Explain what happens in the body when you touch a very very hot object.

Answer 1

the receptor detects to the outside stimulus (heat)
the receptor transmites electrical signals to the sensory neurone
sensory then to the central nervous system (brain)
sensory to relay
the to the motor neurone
and then onto the effector ( muscles in your hand)
muscles in your hand contract causing the hand to move away

Question 2

go and label parts of an eye

Answer 2

search in google: unlabelled annotation of eye diagram igcse, after u finish get answers

Question 3

what is sclera

Answer 3

white protecctive outer layer of the eye

Question 4

cornea

Answer 4

transparent area of sclera at the front of the eyeball that lets light into the eye. Its curved surface changes the direction of light

Question 5

what is iris

Answer 5

it is the coloured, muscular part that contracts and relaxes to change the size of the pupil (to control the amount of light reaching the retina)

Question 6

what is pupil

Answer 6

hole in the middle of the iris which allows light to enter the eye

Question 7

what is the lens

Answer 7

clear disc where light passes through to the retina, it focuses the light onto the retina

Question 8

what is the choroid

Answer 8

dark layer underneath the sclera - contains many pigment cells as well as blood vessels - the pigment is there to stop the light being reflected around inside the eye

Question 9

what is retina

Answer 9

inner-most layer at the back of the eye. this contains photoreceptors (photo=light - so photoreceptors are receptors sensitive to light). these photoreceptors (cone and rod cells) send information to the brain along sensory neurons in the optic nerve)

Question 10

how does the eye focus light

Answer 10

cilliary muscles contract so that the suspensory ligaments are loosen, the lens is pulled thicker and more curved thus focusing light on to the retina more stronger by refracting the light

Question 11

what is accomodation

Answer 11

the ability of the eye to focus light depending on the distance of the object

Question 12

the dilation and constriction of the pupil in response to light is a ……… action

Answer 12

reflex action

Question 13

what is normal body temperature

Answer 13

37 degrees

Question 14

where is the thermoregulatory centre

Answer 14

the thermoregulatory centre is in the hypothalamus of your brain

Question 15

what are thermoreceptors

Answer 15

receptors which detect heat and send impulses to the TRC

Question 16

what is vasodilation

Answer 16

vasodilation - blood vessels that supply the surface skin capillaries dilate (open wide) –> lets more blood flow through the capillaries

Question 17

what is vasoconscriction

Answer 17

the blood vessels that supply skin capllaries constrict so the lumen is narrower causing heat to stay in the body by reducing energy loss, warming it up

Question 18

in bright light what happens to the eye

Answer 18

the circular muscles contract and the radial muscles relax in the iris and the pupil constricts

Question 19

what is a stimulus

Answer 19

stimulus = cells which detect change in the environment (internal/external)

Question 20

write what happens when skin touches hot plate

Answer 20

Skin touches a v hot plate

stimulus ( heat) reaches the recepter ( skin) which sends an electrical signal via the sensory neuron (dorsal root to the spine), which sends a signal to the unconscious part of the brain, which then sends to the motor neuron (ventral root from the spine), then to the relay neuron, and then to the effector ( musclles in hand) which move the hand away from the plat

Question 21

write the reflex arc

Answer 21

receptor –> sensory –> CNS –> relay –> motor –> effector (muscle or glan