Interactive Resources for Schools
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Biology
Human biology
Physical education
PSHE / Citizenship studies
Science (applied)
Biology
Human biology
Science
Biology
Human biology
Physical education
Science
Biology
Human biology
Physical education
Biology
Human biology
Physical education
Human biology
Biology
Physical education
PSHE / Citizenship studies
The digestive systemdigestive system
The organ system in the body which breaks down large insoluble food molecules into small soluble molecules which can be used by the body.
works throughout your life breaking down the food you eat. But sometimes things can go wrong. Problems in the digestive system can be very minor or they can be life-threatening.
Vomitingvomiting
The process of forcing food out of the mouth from the stomach when it is irritated or infected.
is when powerful contractions of the stomach muscles force partly digested food back out through the mouth. It may be the result of irritation or overstretching of the stomach after drinking or eating too much. It can also be caused by infection - some bacteriabacteria
Single-celled organism. Has a cell wall, cell membrane, cytoplasm. Its DNA is loosely-coiled in the cytoplasm and there is no distinct nucleus.
such as Campylobacter and Salmonella can withstand the acid environment of the stomach and infect it. Vomiting is usually mild and only lasts a few hours. However in the very young, the very old and in people who are already weakened by other diseases vomiting can cause death. Worldwide millions of people die each year as a result of vomiting and diarrhoeadiarrhoea
Liquid faeces produced as a result of little or no water being absorbed back into the blood along the colon.
.
Stomach ulcers are formed when the protective layer of mucus in the stomach is damaged or reduced. The acid stomach contents eat into the stomach wall and cause pain. The most common cause of ulcers is infection by bacteria called Helicobacter pylori. Ulcers formed by bacterial infection can be cured using antibioticantibiotic
Medicine that is used to treat bacterial infections and works by killing or stopping the growth and reproduction of bacteria. These can be specific to a particular bacteria or act on groups of related bacteria.
s. Very similar ulcers can also form in the duodenumduodenum
Within the human body this is the first 25-30cm long section of the small intestine.
.
Gall stonesgall stones
Solid masses formed in the gall bladder, often from cholesterol.
may form in the gall bladderbladder
The muscular organ in which urine is collected and stored.
. They are often made of cholesterolcholesterol
A lipid which can be measured in the blood. High levels are linked to an increased risk of cardiovascular disease.
. The gall stones can get very big. If a stone blocks the bile duct, bile builds up in the gall bladder. This can be very painful. The gall stones can be broken down into tiny pieces using ultrasoundultrasound
High frequency sound which cannot be heard by human beings.
. This unblocks the bile duct and allows the bile to flow out into the small intestine again. If the gall stones will not respond to ultrasound, the gall bladder will have to be removed by surgery.
Coeliac diseasecoeliac disease
An immune system reaction to gluten which results in inflammation and loss of the villi in the small intestine.
is caused by a reaction of the cells lining the small intestine to the presence of gluten, a protein found in wheat products. The lining of the gut becomes inflamed and the structure of the villi are lost, so the surface of the ileum becomes smooth. This means the surface area available for the diffusiondiffusion
The spreading out of the particles of a gas or any substance in solution down a concentration gradient.
of digested food molecules into the blood is greatly reduced. People with undiagnosed or unmanaged coeliac disease often become very thin. It cannot be cured but can be managed by removing all the gluten from the diet. This lets the cells of the ileum recover and the villi reform and work normally. Coeliac disease affects about one person in every hundred, so it is important that gluten free foods are readily available.
The difference between a normal ileum and one affected by coeliac disease
Appendicitisappendicitis
An infected or inflamed appendix.
is the result of a blockage or infection in the appendix, a tiny and useless organ at the beginning of the colon. It is very painful. If an infected appendix is not removed by surgery it may burst. This can cause whole body infection and death.
Diarrhoea is when the large intestine or colon is irritated or infected and the food passes through it very rapidly. This means that little or no water is reabsorbed and so the faeces are liquid. In developed countries diarrhoea is often a short-lived and mild illness. However for the very young and the very old, or people who are either malnourished or already ill, diarrhoea can be fatal very rapidly. People die of dehydrationdehydration
The state of the body when it does not have enough water.
and lack of salts in their body as liquid pours out of them. Diarrhoea isn't a disease itself - it is a symptom of many different diseases from E. coli infections to cholera and dysentery. Worldwide around 1.5 million children die every year of diarrhoea, often caught as a result of drinking dirty water contaminated with infected faeces from someone else.