Coordination and response

define the nervous system

a network of specialised cells which carry electrical impulses very quickly from one place to another

diff between CNS and PNS

CNS- brain and spinal column - coordinate response

PNS- sense the world ( sense organs )

motor neuron

nerves that carry electrical impulses from the CNS to muscles

sensory neuron

nerves that carry electrical impulses to the CNS

relay neuron

connects neruons together

direction of electrical impulse

sense organ → stimuli

sensory neuron (to brain)

brain (relay neurons)

motor neuron→effector (response)

reflex action

impulses that do not reach a conscious area of the brain before sent out through motor neurons to cause an action

effectors

muscles or glands that respond to a electrical impulse

receptors

specialised cells which are sensitive to stimuli - often found together in sense organs

what is a synapse

where the action potential is passed on between neurons

what is action potential

an electrical signal that pass from an axon terminal to the dendrites of the next neuron

describe synapse

action potentials cause secretory vesicles to produce neurotransmitters which are collected by receptors to a new neuron from dendrites

adrenal gland hormone location and response

location- on top of kidney

hormone- adrenaline

response- heart rate increase, strength

pituitary gland

location- brain

hormone- growth hormones (FSH, LH)

response- activates other glands and puberty

thyroid gland

hormone- thyroxine

location- below larynx

response- control metabolic rate

accomodation of the eye

the process of adjusting the focus to see objects at different distances

retina

back of the eye, converts light into electrical impuleses using photoreceptors

pupil

circular openong which lets light pass through into the eye

optic nerve

composed f sensory neurons which carry nerve impulses to the visual centre of the brain

vitreous humour

liquid that gives the eye its shape

cornea

transperent layer refraction (bending) of lightv rays that enter the eye

diff between rods and cones

rods- black and white and work best in low light conditions

cones- coloured, work only in bright light

which parts of the eye control light focusing on the re3tina

lens, ciliary muscle, suspensory ligament

iris

coloured part of the eye expands and contracts to control amount of light let into the eye

blind spot

the exit point of optic nerve

homeostasis

a set of processes that our body uses that maintain a stable internal environment

negative feedback mechanism

body returning to its original state

what does insulin and glucagon do

insulin- reduce blood sugar - glucose is converted into glycogen in the liver

glucagon-to increase blood sugar - glycogen is converted into glucose

how does sweating work and what produces it

the sweat glands producesweat and the water evaporates off the skin which removes hest and cools the body down

how do goosebumps work

the hairs are raised by small muslces to trap a layer of air, helps keep heat in

describe vaso dilation

(under hot conition)

blood vessels widen, reduced blood flow to allow heat to escape

vaso constriction

(under cold condition)

Blood vessels narrow, blood flow increases so heat is retained