Bio Topic 7 Flashcards
Which general group of people require the most calories in their diet?
Adolescent males with active lifestyles
Why do pregnant/breastfeeding women need a larger caloric intake?
“They need more energy to support the development of the child. The diet needs to be balanced as well to provide the correct nutrients
“
What is constipation caused by?
A lack of dietary fibre
What is starvation?
Suffering or death that is caused by not eating enough food
What is constipation?
Infrequent bowel movements causing difficulty passing faeces
What is scurvy caused by?
A lack of vitamin C
Give 3 sources of carbohydrates in the diet?
Pasta, bread, potato
Give 3 sources of fat in the diet
Oily fish, nuts, butter
Give 3 sources of protein in the diet
Meat, fish, nuts
Give 2 sources of Vitamin C in the diet
Fruit and vegetables
2 sources of Vitamin D
Oily fish and eggs
Give 2 sources of iron in the diet
Red meat & beans
Give 2 sources of calcium in the diet
Milk and cheese
What are the 2 main groups of dietary fibre?
Soluble fibre and insoluble fibre
Give 2 sources of soluble fibre
Oats and fruit
Give 2 sources of insoluble fibre
Wholemeal bread and nuts
What are the causes of vitamin D deficiency?
“Not enough sunlight
Not enough oily fish, egg yolks or fortified milk”
What are the effects of vitamin D deficiency?
Vitamin D deficiency can cause rickets in children which leads to weak bones which can cause deformities
What are the causes of iron deficiency?
A diet lacking iron, Blood loss, Pregnancy
What are the effects of iron deficiency?
Fatigue, Dizziness, Headache, Chest pain
What is ingestion?
The intake of substances into the body through the mouth
What is mechanical digestion?
The process of breaking down food without altering it chemically
What is chemical digestion?
Breaking insoluble large molecules into smaller soluble ones
What is absorption?
The process where ions and broken down food molecules move into the blood through the wall of the intestine
What is assimilation?
The movement of digested food molecules into the cells of the body where they are used
What is egestion?
The removal of undigested food as waste from the anus
What is cholera?
diarrheal illness caused by infection of the intestine
How does the cholera bacterium cause dehydration and diarrhoea?
1) bacteria, produces a toxin that causes the secretion(too many) chloride ions into small intestine
-This decreases water, potential of small intestine
2) this decreased, what a potential causes water to move from the blood into the small intestine by osmosis
3) leading to diarrhoea and dehydratio
What is the difference between the alimentary canal and the digestive system?
The alimentary canal involves the tubes that the food passes through whereas the digestive system also includes digestive glands
Describe the passage of food through the alimentary canal
“Mouth → oesophagus → stomach → small intestine → large intestine → rectum
“
What is the function of the mouth?
“To chew and break down food
To secrete (produce) digestive enzymes”
What is the oesophagus?
The tube that carries food from the mouth to the stomach
What does the stomach do?
-churns food with its muscular walls
-Produces protease enzymes
-Produces gastric juice to kill bacteria and provide optimum acidic pH for protease
What role does the pancreas play in digestion?
The pancreas secretes digestive enzymes into the small intestine
Where are the salivary glands located?
In the mouth
Name the 2 parts of the small intestine
Duodenum and ileum
What is the function of the duodenum?
The duodenum receives food directly from the stomach and uses enzymes and chemical digestion to break the food down
What is the function of the ileum?
Most nutrients are absorbed from the food in the ileum into the blood
How is the ileum adapted to absorption?
The ileum is lined with villi and microvilli which provide a large surface area for absorption
How are villi adapted for absorption?
Microvilli = larger surface area for faster absorption
Wall of villus one-cell-thick: shorter distance for diffusion + active transport
Network of blood capillaries: transport glucose + amino acids away from s.i. & into blood
Lacteal: runs through centre of villus to transport fatty acids & glycerol away from s.i. & into lymph
What is the function of the large intestine (colon)?
Water is reabsorbed into the blood in the large intestine
What is the function of the rectum?
“The rectum stores faeces before egestion
“
“What is the function of incisors in mechanical digestion?
“
Biting and cutting
“What is the function of canines in mechanical digestion?
“
Gripping and tearing
What is the function of premolars and molars in mechanical digestion?
“Chewing and grinding food
Molars- crushing + grinding
Premolars- tearing and crushing
What is the purpose of chemical digestion?
Breaking larger insoluble molecules into smaller soluble molecules that can be absorbed
What does amylase do?
Amylase is a digestive enzyme that breaks starch down into simple sugars
“Describe the digestion of starch in the alimentary canal
“
“Amylase is secreted and breaks starch down into maltose in the alimentary canal
Maltase breaks maltose down on the membranes of the small intestine”
What does protease do?
Protease is a digestive enzyme that breaks proteins down into amino acids
What does lipase do?
Lipase is a digestive enzyme that breaks lipids down into fatty acids and glycerol
Give 2 places in the alimentary canal that amylase is secreted
The pancreas, The salivary glands in the mouth
Give 3 places in the alimentary canal that protease is secreted
The pancreas, The stomach, small i testine
Where is lipase secreted?
The pancreas
Give 2 examples of protease enzymes
Pepsin and trypsin
Where is trypsin secreted from?
The small intestine
Where is pepsin secreted from?
The stomach
“Explain the functions of hydrochloric acid in gastric juice
“
“Low (acidic) pH kills bacteria by denaturing the enzymes inside them
Low pH is the optimum pH for pepsin”
What does bile do?
“Bile neutralises the stomach acid and provides alkaline conditions for the digestive enzymes in the small intestine
Bile also emulsifies fats which increases their surface area for chemical digestion”
In which part of the alimentary canal is digested food absorbed?
The small intestine
What is the purpose of villi in the small intestine?
Villi increase the surface area for absorption
Describe the structure of a villus
“Central lacteal used for transporting fatty acids and glycerol in the lymph fluid
Lots of capillaries to absorb nutrients into the blood
Thin wall to minimise the diffusion distance”
Where is water absorbed
“The small intestine (most water absorbed here)
The colon”
