7. Human Nutrition Flashcards
Oesophagus
The tube-like structure that transports food in the form of bolus to the stomach.
Stomach
A muscular compartment where food is mixed and digested into small pieces. The food is mixed with the enzyme, pepsin and hydrochloric acid to form a liquid called chyme.
Small Intestine
The longest section of the digestive system where food is digested into nutrients and absorbed.
Liver
Organ that produces bile, which emulsifies fats and neutralises the acidic chyme from the stomach.
Gallbladder
Sac-like structure which stores bile before release into the duodenum.
Pancreas
A gland located behind the stomach that secretes digestive enzymes, and the hormones insulin and glucagon.
Secretes pancreatic juice which has trypsin, amylase and lipase in it.
Large intestine
Section of the digestive system where absorption of water and salts from undigested food takes place
Rectum
Holds the undigested food, called stool. for excretion.
Anus
Egestion of food occurs at this opening in the digestive system, which is controlled by muscular valves.
Ingestion
The procedure by which something is taken into the body
Egestion
Process by which remainder of food leaves the body
Peristalsis
-Muscle movement forcing the food along
Small intestine
-Part of the digestive system where nutrients are absorbed
Large Intestine
Part of the digestive system where the food loses water
Digestion
Breakdown of large insoluble molecules into small soluble molecules
Alimentary canal
Continuous tube that runs through the torso and contains most parts of the digestive system
Metabolism
All the chemical reactions that happen inside living cells, including respiration.
Nutrients needed for a balanced diet
Carbohydrates
Fats
Proteins
Vitamins
Mineral Ions
Fibre (Roughage)
Water
Carbohydrates
Compounds found in living things composed of carbon, hydrogen and oxygen.
Fats
A compound that consists of glycerol and fatty acids.
Proteins
Proteins are made of the biological building block called an amino acid. Proteins are used to synthesise muscle, skin, bone, skin and enzymes.
Vitamins
A group of micronutrients essential for healthy metabolic processes, found in fruits and vegatables.
Mineral Ions
Calcium and iron are important examples of mineral ions. Each mineral has a unique function in the body.
Fibre
The fibrous indigestible component of foods.
Water
Water makes up two-thirds of the weight of the human body and is an important component in maintaining a balance of substances (homeostasis).
Carbohydrates - Main sources, Dietary importance
fruit, vegetables, pasta, bread, potatoes
provide energy
Fats - Main sources, Dietary importance
avocado, nuts, olive oil, oily fish
provide energy
Proteins - Main sources, Dietary importance
meat, fish, eggs, beans, pulses, nuts
growth and repair
Vitamin C - Main sources, Dietary importance
oranges, red peppers, kale, broccoli
maintains healthy blood vessels, skin, cartilage and bones, helps with wound healing
Calcium - Main sources, Dietary importance
milk, sardines, broccoli, kale, okra, spinach
strengthens bones and teeth, and helps with muscle contraction and clotting of wounds
Iron - Main sources, Dietary importance
red meat, beans, nuts
production of haemoglobin for red blood cells
Fibre - Main sources, Dietary importance
cereals, vegetables, fruit, brown rice, nuts, potatoes
helps digestion, and helps to move food and faeces along the gut
Reduces risks of coronary heart disease, type 2 diabetes and bowel cancer
Water - Main sources, Dietary importance
water and other drinks
about 60% of body mass is water, and it is needed in almost every process
Deficiency Disease
Illness caused by the insufficient intake of a nutrient in the diet, or by the inability to absorb it efficiently.
Rickets - Deficiency + Symptoms
Deficiency
vitamin D
Symptoms
bone pain
weakness in the muscles
Increases risk of fractures and skeletal deformities.
Scurvy - Deficiency + Symptoms
Deficiency
vitamin C
Symptoms
severe leg pain or joint pain
tiredness
weakness
blue or red spots on the skin, which bruise easily
swollen and bleeding gums
Ingestion - Complex description
Food and drink ingested into the mouth by igestion. Once there, they form a bolus –> then swallowed. Waves of muscle contraction in wlals of oesophagus push bolus into the stomach.
Physical Digestion
The breakdown of food into smaller pieces without chemical change to the food molecules.
By braeking food into smaller pieces the surface area to volume ratio increases –> Easier for enzymes to break down food.
This happens in…
The mouth –> teeth grind food into smaller pieces
The stomach –> movements of the stomach walls break food into small pieces.
Chemical digestion
The breakdown of large, insoluble molecules into small, soluble molecules.
This happens in…
The mouth –> Saliva includes amylase - Breaks down starch to simple reducing sugars
The stomach –> Pepsin (a protease) in the stomach breaks down proteins into amino acids.
The small intestine - Trypsin (a protease) in the small intestine breaks down proteins into amino acids
What are the parts of the digestive system that aren’t a part of the alimentary canal?
Salivary Glands
Liver
Gall Bladder
Pancreas
Salivary Gland
Produces saliva –> which is secreted into the mouth.
Saliva mixes wth ingested food –> makes it soft + easier to swallow.
Saliva contains amylase (enzyme breaking down starch into simple reducing sugars)
Liver
Organ that produces bile, which emulsifies fats and neutralises the acidic chyme from the stomach.
Gall bladder
Sac-like structure which stores bile before its released through the bile duct into the duodenum.
duodenum
The first section of the small intestine where pancreatic juices mix with the chyme from the stomach to digest food into absorbable nutrients.
ileum
The last section of the small intestine where the nutrients are absorbed into the blood system.
Pancreas
Organ which creates and secretes pancreatic juice. (lipase, maltase, trypsin. Pancreatic juice is alkaline.
Assimilation
The movement of digested food molecules into the cells of the body where they are needed
Bile
Alkaline liquid that neutralises the acidic mixture entering the duodenum from the stomach, and emulsifies fats.
Fats can’t dissolve in water –> lipase can’t break them down –> so they are emulsified (broken down into small droplets) –> their surface area increases –> allows lipase to digest lipids into fatty acid + glycerol.
Alkaline bc it contains high concentration of hydrogencarbonate ions. –> can neutralise acidic mixture of gastric juice + food as it enters duodenum form the stomach –> important bc amylase + trypsin work best under alkaline conditions.
Incisors
Teeth with sharp, blade-like features, for cutting food (e.g. biting an apple)
(Four front teeth)
Canines
Strong, pointed teeth for tearing food (e.g. tearing off a piece of tough meat).
Two teeth surrounding incisors (four front teeth)
Premolars
Teeth with combined features of canines and molars for grinding and tearing food.
(two teeth before molars)
Molars
Flat, broad teeth used for crushing and grinding food (e.g. nuts).
(Three last teeth)
Enamel
Hard glossy substance that forms the thin outer layer of a tooth.
–> a calcium phosphate material. Made by calcium obtained in diet + assimilated into teeth and bones.
Dentine
Hard bone-like substance, but softer than enamel, that forms the middle section of teeth.
–> most of the tooth is made from dentine (surrounds + connects to the pulp)
Pulp
Centre portion of teeth containing blood vessels and nerves.
Nerves in tooth
In a tooth the nerve is sensitive to pressure, temperature and pain.
–> attatched to the teeth, through holes in the bottom of each tooth.
Cement
Substance that attaches teeth to the bone of the jaw.
Gums
Soft tissue that surrounds the teeth, forming a tight seal around them to keep them in place.
Amylase
Enzyme that breaks down starch to maltose.
Amylase break down starch to simple reducing sugars (eg. glucose and maltose) or simple sugars.
Another enzyme named maltase breaks down maltose to form glucose on the epithelium lining the small intestine.
Secreted in the salivary gland, pancreas
Acts in the mouth, small intestine
Needs appoximately pH 7
Maltase
Enzyme that breaks down maltose to glucose.
Optimum pH 6.5
Protease
Protease enzymes break down proteins into amino acids.
Two types of protease…
Pepsin, Trypsin
Secreted in the stomach, small intestine
Acts in the stomach, small intestine
Pepsin
Protease enzyme found in the stomach.
–> requires an acidic environment (low pH)
Secreted in the stomach
Acts in the stomach
Trypsin
Protease enzyme found in the small intestine.
–> requires an alkaline environment, (high pH)
Secreted in the pancreas
Acts in the small intestine
Passes from the pancreas into the duodenum.
Lipase
Type of enzyme that breaks down fats to fatty acids and glycerol.
Secreted in the pancreas.
Acts in the small intestine
Gastric juice
A mixture secreted in the stomach. Contains hydrochloric acid –> gives it a pH 1.5 to 3.5 (strongly acidic).
–> low pH provides optimum pH for the protease activity in the stomach.
+ causes the denaturation of enzymes in harmful microorganisms in food, reducing the chance of food poisoning.
Digestion of starch to glucose
Amylase breaks down starch to maltose.
Maltase breaks down maltose to glucose.
Amylase secreted by salivary glands + acts in teh mouth. Also secreted by pancreas + acts in the small intestine.
Maltase secreted in small intestine + acts on membranes of epithelium lining the small intestine
Digestion of protein
Pepsin + Trypsin both digest proteins into amino acids.
Pepsin - acts in stomach (acidic)
Trypsin - actis in small intestine (alkaline)
Absorption
The movement of ions and small food molecules through the wall of the intestine into the blood.
Digested food is absorbed in the small intestine
Water is absorbed in the small intestine AND in the colon. (main part of large intestine)
Villi
(Plural: villi) Tiny finger-like projection on the surface of the small intestine that increases its surface area for absorption. (villus singular)
Microvilli
Folds in the cell membrane of cells lining the outside of a villus, further increasing the surface area needed for rapid absorption.
Structure of a villus
Epithelium cells lining it.
Blood capillaries cloes to surface for efficient absorption.
Lacteal (around whihc the blood capillaries are wrapped) for absorption of fats into the lymphatic system
Lacteal
Structure in a villus where absorption of fat happens.
Lymphatic System
Organ system consisting of lymphatic vessels and lymph organs.
