Science form 2
-
Upload
ain-azmi -
Category
Health & Medicine
-
view
12.232 -
download
1
Transcript of Science form 2
SCIENCE FORM 2
THE WORLD THROUGH OUR SENSES
THE SENSORY ORGANS
Main sensory organsSKINNOSETONGUEEAREYE
FUNCTION OF MAIN SENSORY ORGANS
SKINDetect touch,pressure, pain, heat,
cold.Organ for touch.
NOSEDetect chemicals.Organ for smell.
TONGUEDetect chemicals. Organ for taste.
EARDetect sound.Organ for hearing.
EYEDetect light.Organ for sight.
THE HUMAN NERVOUS SYSTEM
♥Responsible for detecting stimuli and changes in the environment and sending the information to the brain for interpretation.
♥The brain then send out instructions to the relevant parts of the body for actions to be taken.
♥The information and instructions are send out in the form of nervous impulses along nerves.
♥The nervous system consists of the brain, the spinal cord and the nerves.
♥The brain and the spinal cord form the central nervous system.
♥The nerves which send nerves impulses from the sensory organs or receptors to the brain are called the sensory nerves.
♥The nerves which carry nervous impulses from the central nervous system to the muscles or glands for carrying out the responses are called the motor nerves.
THE PATHWAY FROM STIMULUS TO RESPONSE
StimulusSensoryorgans
Sensory nerves
BrainMotor nerves
Responses
THE SENSES OF TOUCH
THE SKIN AS A SENSORY ORGAN
THE SKIN
♥The skin is made up of two layers: -the epidermis -the dermis♥The skin is a sense organ helping
the body to know what is happening in its surroundings.♥The nerve endings or receptors in
the skin detects stimuli
THE FUNCTION OF RECEPTORS
TOUCH RECEPTORDetects any contact made with the
skin.
PRESSURE RECEPTORDetects pressure exerted on the
skin.
PAIN RECEPTORDetects pain when the skin is
injured.
HEAT RECEPTOR Detects heat or any that rise in temperature.
COLD RECEPTOR Detects a cold substance or any fall in temperature.