coordination and response

stimulus

change in the environment

response

how we react to it

receptor

what detects the change

effector

what carries out the response

what needs to be controlled in our bodies

temp, water levels, blood glucose levels

what is homeostasis

maintaining constant internal environment

2 organ systems in coordination

nervous = nerves, endocrine = hormones

what is geotropism

how plant grows in response to gravity

positive - roots grow down

negative - shoots grow up

what is phototropism

how plant grows in response to light

positive- shoot grows towards light(towards stimulus)

what is an auxin

plant growth hormone, produced near tip and diffuse down plant, more auxin = more growth, helps plant bend towards light

function of nervous system

enables organisms to react to their surroundings and coordinate behaviour, brain + spinal cord, a nerve is a bundle of neurones

function of endocrine system

regulates biological processes in the body through the release of hormones, pit glands

how is information sent in nervous system

sent along nerves as electrical impulses

how is information sent in endocrine systems

as chemical substances called hormones through blood

involuntary vs voluntary response

if impulse foes to spinal cord = involuntary

what is the reflex arc

pathway of a reflex repsponse

order of a reflex arc

stimulus, receptor, sensory, relay(brain), motor, effector

comparison of three types of neaurone

motor + sensory→ no nucleus, myleine sheath

relay → no myleine sheath, nucleus

all have: cell body, axon terminals m

what is a synapse

a small gap because neurones dont directly come to contact

what chemical used to get across synapse

neurotransmitters, electrical impulses are carried by axons → triggers production of neurotransmitters→ vesicles move towards synapse → attach to receptors on second neurone → triggers electric impulse

what controls pupils size in dim and bright light

circular and radial muscles

bright light: circular contract, radial relax → pupil gets smaller, reduce light entering

dim light: circular relax, radial contract → pupil gets bigger, more light in

what controls pupils size for seeing close and far away

ciliary muscles, suspensory ligs

distant: cil relax, sus contract → lens gets thinner for clear distant vision

near: cil contracts, sus relax → lens gets curved for clear near vision

how does eye detect light

uses rods and cones, cones detect colour and need high light levels to function, rods are more sensitive and work well in dim light. the light receptors detect stimulus of light and send message to brain via optic nerve

what is vasodilation

blood vessels relax their muscles to allow more blood through, more blood at surface so it can lose heat

what is sweating

as water evaporates it uses energy, cools down person as heat energy is lost

what is vasoconstriction

when blood vessels contract their muscles to allow less blood through, less blood at surface and looses less heat, reduces heat loss