MINERALS WHICH IS NEEDED TO MAKE HAEMOGLOBIN IN RED BLOOD CELLS
VITAMINS TO PREVENT SCURVY
FIBRE WHICH PREVENTS CONSTIPATION
WATER WHICH PREVENTS DEHYDRATION
BMI
BMI- mass (kg) divided by height (m)2 squared
BLOOD PRESSURE
blood pressure is a measure of the force of blood per unit area as it flows through the arteries
IT IS MEASURED IN mmHg which means millimetres of mecury
Blood pressure is at its highest when the heart muscle contracts forcing blood into the arteries to all parts of the body.
THIS IS CALLED SYSTOLIC BLOOD PRESSURE
When the heart relaxes the pressure in the arteries drops. THIS IS CALLED DIASTOLIC BLOOD PRESSURE
THE NERVOUS SYSTEM
A SENSORY NEURONE
Carries nerve impulses from the receptors to the CNS
A RELAY NEURONE
makes connections between neurones inside the brain and spinal cord
A MOTOR NEURONE
Carries nerve impulses from the CNS to the muscles and glands
the central nervous system is made up of the spinal cord and the brain
light receptors in the retina of the eye detect light
sound and change of position receptors in the ears (for balance)
taste receptors on the tongue detect chemicals in food
smell receptors in the nose detect chemicals in the air
touch, pressure, pain and temperature receptors in the skin.
EFFECTORS are the muscles or glands that make the change in response to the signal from the receptor
REFLEX ACTION
GIVE FAST AUTOMATIC RESPONSES TO STIMULUS HELPING TO PROTECT THE BODY FROM HARM.
EXAMPLES
knee jerk reaction
withdrawing your hand from a hot plate to prevent burning yourself
LONG SIGHT
LONG SIGHT IS CAUSED BY AN EYE BALL THAT IS TOO SHORT OR BY A LENS THAT DOESNT SHAPE PROPERLY, IT CAN BE CORRECTED BY A CONVEX LENS WITH CONVERGES THE LIGHT RAYS FROM CLOSE OBJECTS SO THAT THEY FOCUS ON THE RETINA
IS WHEN YOU CAN SE DISTANT OBJECTS CLEARLY BUT NOT CLOSE OBJECTS
SHORT SIGHT
SHORT SIGHT IS CAUSED BY AN EYEBALL THAT IS TOO LONG OR WEAK, IT CAN BE CORRECTED BY A CONCAVE LENS WITH DIVERGES THE LIGHT RAYS SO THAT THEY FOCUS ON THE RETINA
SHORT SIGHTEDNESS IS WHEN YOU CAN SEE NEAR OBJECTS CLEARLY BUT NOT DISTANT ONES