Topic 11.1 How do humans' bodies respond to changes inside
them and to their environment?
Explain what a stimulus is by highlighting examples and what organs they stimulate.
Describe how a nervous response is brought about by stimuli, including the roles of
receptors, sensory neurones, the coordinator and motor neurones.
Stimulus (Light bulb) -> Receptor (Eye) -> impulse travels along the
sensory neurone to -> Coordinator (Brain) -> impulse travels along
the motor neurone to -> Effector (Eye muscle) -> Response
Neurone = A single nerve
Describe a reflex action and the role of the relay neurone in this action.
Receptor (Finger) -> impulse travels along sensory neurone -> comes
to synapse -> goes onto the relay neurone -> to synapse -> along the
motor neurone -> Effector (Arm muscle)
Synapse = gaps between the
end of a neurone and the
start of another or an
Axon = the end of a neurone.
Explain that four internal
conditions controlled by the body
include; water content, ion
content, body temperature and
blood sugar. Describe, in very
broad outline, how they are
Ion content leaves body 1) in sweat 2) excess lost via kidneys in
The water content of body leaves body 1) in breath 2) as sweat 3)
excess is lost via kidneys in urine.
Temperature -> maintain temperature at which enzymes work best.
Blood sugar levels -> to provide the cells with a constant supply of
Describe hormones as chemicals which coordinate reactions in the body and that are
secreted by glands and reach their target organs via the blood stream.
Pituitary glands -> FSH and LH.
Ovaries -> oestrogen and progesterone.
Biology Revision (Year 9/10) 2008
Other pages in this set
FSH (Follicle stimulating hormone) egg mature + oestrogen to be
Oestrogen thickens uterus lining + inhibits FSH
LH (Luteinizing hormone) egg is released from ovary + stimulates
Describe how hormones control both the monthly release of an egg and the varying
thickness of the lining.
Recall the location of the pituitary gland and the ovaries and that they are the main
hormone glands for the release of the menstrual cycle hormones.
Discuss the problems associated with the lack of food in the developing world that
include; reduced resistance to infections and irregular periods in women.
Recall that cholesterol is a substance made by the liver and found in the blood.
Explain that cholesterol levels in the blood are dependent on both inherited factors
and diet. High levels of cholesterol increase the chance of arteriosclerosis and heart
Recall that lipoproteins carry cholesterol round the blood. One type,
low-density-lipoprotein LDL, can cause heart disease.
Cholesterol is a substance made in the liver. It is found in the blood stream. The amount
of cholesterol produced by the liver depends on a combination of diet and genes. High
levels of cholesterol in the blood increases the risk of disease of the heart and blood
Cholesterol is carried around the body by two types of lipoproteins.
Low-Density-Lipoprotein (LDL) are bad cholesterol and can cause heart disease.
High-Density-Lipoprotein (HDL) are good cholesterol. The balance of the two is very
important to health.
- Wet tar?
Sir Richard Doll was commissioned by the Medical Research Council to investigate a
possible link between smoking tobacco and lung cancer.
He visited 2000 people suspected of having lung cancer and found that those who had the
disease were heavy smokers.
Date What happened?
1954 The Government accepted that there was a strong link between tobacco and lung
1970s The link began to be taken more seriously and the media began to discuss it
Disinfectant (for non-living tissue)
He noticed that in a normal hospital, where doctors delivered babies, the
mortality rate was higher (10%) compared to in a maternity hospital where maternity
nurses delivered babies (1%).
Occurs during infection. It is active because your body fights an invading
pathogen with antibodies
o Used during potentially fatal diseases. Injection of readymade antibodies
provides an instant temporary response. Eg tetanus and rabies
o Injecting or taking dead pathogens by mouth.