human nutrition Flashcards
a balanced diet contains:
- Carbohydrates
- Proteins
- Water
- Fiber
- Mineral ions (eg, calcium and iron)
- Vitamins
- Fats
carbohydrates - main sources and dietary importance
fruit, vegetables, pasta, bread, potatoes
provide energy
fats - main sources and dietary importance
avocado, nuts, olive oil, oily fish
provide energy
proteins- main sources and dietary importance
meat, fish, eggs, beans, pulses, nuts
growth and repair
vitamin C- main sources and dietary importance
oranges, red peppers, kale, broccoli
maintains healthy blood vessels, skin, cartilage and bones
helps with wound healing
vitamin D- main sources and dietary importance
salmon, cheese, eggs
helps to regulate the amount of calcium and phosphate in the body, necessary to keep teeth, bones and muscles healthy
calcium- main sources and dietary importance
milk, sardines, broccoli, kale, okra, spinach
strengthens bones and teeth, and helps with muscle contraction and clotting of wounds
iron- main sources and dietary importance
red meat, beans, nuts
production of haemoglobin for red blood cells
fibre- main sources and dietary importance
cereals, vegetables, fruit, brown rice, nuts, potatoes
helps digestion, and helps to move food and faeces along the gut
associated with lower risks of coronary heart disease, type 2 diabetes and bowel cancer
water- main sources and dietary importance
water and other drinks
about 60% of body mass is water, and it is needed in almost every process
scurvy is due to
lack of vitamin C
rickets is due to
lack of vitamin D
ingestion definition
taking substances (food and drink) into the body through the mouth
digestion definition
breaking food down into nutrients
absorption definition
the movement of small food molecules and ions through the wall of the intestine into the blood
assimilation definition
the movement of digested food molecules into the cells of the body where they are needed
egestion definition
passing out food that has not been digested or absorbed
physical digestion definition
breaking down of food into smaller pieces without any chemical change (in the mouth and stomach where muscles in the stomach contract)
chemical digestion definition
breaking down large insoluble molecules in food into small, soluble molecules, with the help of enzymes (in the mouth, stomach and small intestine)
journey that food takes
mouth → oesophagus → stomach → small intestine → large intestine → anus
small intestine consists of:
ileum, duodenum
large intestine consists of:
colon, rectum
human digestive system (top to bottom)
- Mouth
- Salivary glands
- Oesophagus
- Liver
- Stomach
- Gall blader
- Pancreas
- Small intestine - ileum duodenum
- Large intestine - colon rectum anus
salivary glands function
produces saliva. Saliva mixes with ingested food so that it is softer and easier to swallow. Saliva contains the enzyme amylase which helps in breaking down starch into simple reducing sugars
Liver and gall bladder function
produces bile which is important in the digestion of fat. Bile is stored in the gall bladder before it is released through the bile duct into the duodenum
oesophagus function
Transports food to the digestive system
Pancreas function
releases pancreatic juice that helps in the digestion of carbohydrates, proteins and fats. Pancreatic juice is alkaline, helps to neutralize acid in food leaving the stomach
liver function
Creates bile to break down fats and neutralize acid
large intestine function
Absorbs water and salts from undigested food
stomach function
Uses enzymes and acids to break down food
pancreas function
Secretes hormones and digestive enzymes
small intestine function
Absorbs nutrients from food
Rectum function
Stores undigested food for egestion
incisors
sharp, blade-like for cutting food
canines
pointed, strong for tearing food
premolars
combined features of canines and molars for tearing and grinding food
molars
broad, flat surface for crushing and grinding food
Structure of a tooth
(From out inwards)
Enamel
Dentine
Pulp
Blood vessels
Cement
Nerve
enamel feature
White, hardest part of the tooth, calcium phosphate mineral
dentine feature
Bone-like substance, softer than enamel
pulp feature
Contains blood vessels and nerves
cement feature
Attaches the teeth to the jawbone
gum feature
Helps to keep the teeth in place
Two different types of protease enzyme in the alimentary canal
TRYPSIN and PEPSIN
where is amylase secreted?
salivary glands and pancreas
where is protease secreted?
stomach and small intestine
where is lipase secreted?
pancreas
where is maltase secreted?
stomach
where is trypsin secreted?
pancreas
where does amylase act?
mouth and small intestine
where does protease act?
stomach and small intestine
where does lipase act?
small intestine
where does trypsin act?
small intestine
where does maltase act?
stomach
where does pepsin act?
stomach
where is pepsin secreted?
stomach
under which conditions does pepsin act?
acidic conditions
under which conditions does trypsin act?
alkaline conditions
where is water absorbed?
small intestine and colon
where is digested food absorbed?
small intestine
villi definition
tiny finger-like projection on the surface of the small intestine that increases its surface area for absorption
microvilli definition
even smaller villi in the surface of the villus. Folds in the cell membrane of cells lining the outside of a villus. Further increasing surface area for absorption
Increase surface area for absorption in the small intestine
the structure of a villus includes:
- Epithelium (surface of the villus)
- Lacteal (responsible for the absorption of fats into the lymphatic system)
- Blood capillaries
- Circulatory system
- Lymphatic system
