Human Biology (Digestive and Excretory) Flashcards
(53 cards)
List the types of digestion.
Mechanical digestion, chemical digestion
Describe the purpose of digestion.
To extract the nutrients from the food we eat and absorb them for use by the cells.
List two similarities and two differences between mechanical and chemical digestion.
Similarities: Both take something larger and make it smaller. Mechanical and chemical
digestion occurs in the mouth, stomach and small intestine.
Differences: Mechanical digestion is a physical process, so no new substances are formed.
Chemical digestion produces new products from larger, more complex molecules. Chemical
digestion requires enzymes, mechanical digestion does not.
People who have had their gall bladder removed are unable to control the release of bile
into the small intestine. Predict a consequence of this.
They will have difficulty digesting fats, which may lead to diarrhoea
List the structures of the alimentary canal in order, starting from the mouth.
Mouth→ pharynx → oesophagus → stomach → small intestine → large intestine →
rectum → anus
List the enzymes that are present in pancreatic juice.
Pancreatic amylase; Pancreatic protease / trypsin; Pancreatic lipase; Deoxyribonuclease
and ribonuclease
Describe the function of the large intestine.
To absorb water and mineral nutrients and to form faeces.
What type of digestion (mechanical or chemical) occurs in the stomach?
Both types occur in the stomach. Mechanical digestion occurs with the stomach, churning
the food and producing chyme. Chemical digestion of proteins occurs with the release of pepsin.
Explain how the lining of the small intestine maximises the absorption of nutrients
The lining of the small intestine (mucosa) is folded to increase the surface area. The
mucosa has small projections called villi; the villi have microvilli projecting from the external
surfaces. This increases the surface area to allow for maximum absorption of nutrients.
Herbivores, such as horses, have reduced canines and large premolars and molars.
Explain the relevance of this.
Canines are used for tearing, which is needed more by carnivorous animals than
herbivores. Large premolars and molars allow for grinding and crushing food to access the nutrients
found in plant material, which is why herbivores have larger molars and pre-molars.
What is the common name for colorectal cancer?
Bowel cancer
List two conditions that are more likely with a diet low in fibre
Bowel cancer, diarrhoea, constipation
Define ‘diarrhoea’.
Frequent defecation of watery faeces caused by irritation of the small or large intestine.
Explain the difference between diarrhoea and constipation.
Diarrhoea is frequent passing or watery faeces, whereas constipation is a condition where
defecation is difficult because the faeces have become hard and dry.
Identify the treatment for coeliac disease and justify its effectiveness.
The treatment is to follow a gluten-free diet. This is because the presence of gluten (a protein found in wheat, barley and rye) causes the immune system to damage and destroy the villi
in the small intestine, which leads to a lack of nutrients being absorbed and malnourishment.
Explain the relationship between peristalsis and diarrhoea.
Peristalsis is the rhythmic contraction of the smooth muscle of the alimentary canal used to
propel food along the tubes. Diarrhoea occurs because of rapid peristalsis, moving the contents of
the intestine more quickly, limiting the absorption of water.
Explain why it is important for people to eat fruit and vegetables.
Fruit and vegetables contain cellulose/insoluble fibre. Although we are unable to digest
cellulose, it is required to help move the contents of the large intestine along. Without it, the movements
of the large intestine become slower, more water is absorbed, and constipation can result.
List the organs involved in excretion.
Lungs, liver, sweat glands, kidneys, alimentary canal
Describe how the alimentary canal is involved in excretion.
The alimentary canal passes out bile pigments. Bile pigments are the products from the
breakdown of haemoglobin from red blood cells.
Summarise how amino acids are broken down and removed from the body.
Amino acids go through a process of deamination, a byproduct of which is urea, which is
filtered out by the kidneys and is present in urine.
Some people are living donors. This means that they are alive when they donate an
organ such as a kidney to someone else. Explain how they are able to do this and still
remain healthy.
The living donor still retains one kidney, and that kidney will increase in size to
compensate for the loss of the second kidney. Blood is filtered through the kidney and the waste
products are removed to form urine.
People who consume excess alcohol have a higher risk of liver problems. Suggest why this is so.
The liver detoxifies alcohol, in doing so, undergoes oxidative stress.
This is where the product from the detoxifying damages the liver cells causing inflammation and scarring.
Define ‘deamination’.
The removal of an amino group from an amino acid molecule.
Name the functions of the skin in excretion.
The skin contains sweat glands that secrete sweat containing mostly water, but also salts
urea and lactic acid, which are all byproducts of metabolism.
