The Human Digestive System Flashcards
Herbivores e.g.
Animals that feed only on plants e.g. rabbit
Carnivores e.g.
Animals that feed on other animals e.g. fox
Omnivores e.g.
Animals that feed on plants and animals e.g. badger
Why is there a need for digestion?
To break down large food particles until they are small enough to pass into body cells.
Why is there a need for a digestive system?
Food can be digested in a single location. Individual cells do not have to contain a full range of digestive enzymes.
Ingestion
Food is taken into the alimentary canal
Digestion
The physical and chemical breakdown of food into soluble particles small enough to pass into body cells.
Absorption
The movement of digested material from the alimentary canal into the blood system.
Egestion
Removal of unabsorbed material as faeces.
Nutrition
The way an organism obtains and uses it’s food.
Autotrophic
A type of nutrition where organism make its own food.
Heterotrophic
A type of nutrition where organism cannot make its own food.
What is the human dental formula?
The number of each type of tooth in the upper jaw one side of the mouth.
Where do symbiotic bacteria function?
The large intestine
What types of mechanical digestion are used to breakdown food?
- Teeth 2. Contractions in the stomach wall 3. Peristalsis
Peristalsis
Rhythmic muscular contraction and relaxation in the wall of the alimentary canal causing the food to move along the canal
Name the different types of teeth
Incisors, Canines, Pre molars, Molars
Incisors
Cutting
Canines
Tearing
Pre molars
Crushing and grinding
Molars
Crushing and grinding
Give the human dental formula
i 2/2 c 1/1 pm 2/2 m 3/3
Name the parts of the human digestive system
Mouth, Salivary Gland, Pharynx, Oesophagus, Liver, Stomach, Gall bladder, Pancreas, Bile duct, Small intestine (Duodenum, Ileum), Large intestine (Colon, Caecum, Appendix, Rectum, Anus)
What is the oesophagus?
A muscular tube 25cm long that connects the pharynx to the stomach that food moves down by peristalsis.
What connects the pharynx to the stomach?
The oesophagus
How does food move down the oesophagus?
Peristalsis
What is the stomach?
A J-shaped muscular bag which stores and digests food for about four hours and churns and mixes food with gastric juice forming Chyme.
What is the shape of the stomach?
J-shaped
What is the function of the stomach?
It stores and digests food for about four hours and churns and mixes food with gastric juice forming Chyme.
What does the stomach mix with food and what does this create?
gastric juice, Chyme
What are the two types of digestion in the stomach?
Mechanical and Chemical digestion
How does mechanical digestion occur in the stomach?
Peristalsis physically breaks up food particles
How does chemical digestion occur in the stomach?
Chemical digestion occurs using gastric juice containing mucus, HCl and pepsinogen.
What does gastric juice contain?
Mucus, HCl and pepsinogen
What are the functions of gastric juice?
Mucus lines and protects the stomach wall, HCl kills bacteria and activates pepsinogen and pepsinogen is converted to the active enzyme Pepsin by HCl. Pepsin digests protein to peptides.
What is Pepsin and what does it do?
Pepsin in an active enzyme that digests protein to peptides.
What and where is the cardiac sphincter muscle?
A circular muscle which contracts to close entry from the oesophagus to the stomach.
What and where is the pyloric sphincter muscle?
A circular muscle which contracts to close the entry from the duodenum to the stomach. (open when relaxed)
What is the small intestine?
A muscular tube 5-6m long that carries out digestion and absorption. It has three parts, the duodenum, the jejunum and the ileum.
What is the small intestine?
A muscular tube 5-6m long that carries out digestion and absorption. It has three parts, the duodenum and the jejuneum/ileum.
What are the functions of the small intestine?
digestion and absorption
What are the two parts of the small intestine?
The duodenum and the jejuneum/ileum
What is the duodenum?
A 25cm muscular tube where most digestion takes place.
What is the Jejuneum/Ileum?
A long tube that absorbs nutrients and contains villi.
What is the Ileum also known as?
The Jejuneum
What is the function of the Jejuneum/Ileum?
To absorb nutrients
How has the Jejuneum/Ileum adapted to allow for absorption?
- It is a long tube which allows time for absorption to take place.
- It contains villi which are infoldings which increase the surface area available for the absorption of food.
What are villi and what are their function?
Infoldings in the lining of the small intestine which increase surface area for absorption of digested food.
What is the singular of villi?
Villus
Where is a lacteal and what is it’s function?
In a villus. To absorb fatty acids and glycerol.
What is absorbed into the blood in the villus?
All digested food except fatty acids and glycerol.
What are the functions of the large intestine (colon)?
To reabsorb water, produce B group vitamins and digest cellulose.
What produces B group vitamins and digests cellulose in the large intestine?
Symbiotic bacteria
What is the function of the caecum?
It is vestigial - has lost it’s former use and therefore it’s function is unknown to humans
What is the function of the appendix?
It is vestigial - has lost it’s former use and therefore it’s function is unknown to humans
What is the function of the rectum?
To store faeces
What is the role of the liver in digestion?
The liver produces bile
What is bile?
A yellow-green liquid
Where is bile stored?
The gall bladder
Where does bile enter the duodenum through?
The bile duct
What does bile consist of?
Water, bile salts and bile pigments
What is the function of bile?
It emulsifies fat which increases the surface area of the fat droplets. It also neutralises the acidic chyme from the stomach.
What are the benefits of dietry fibre
Fibre stimulates peristalsis in the colon and helps to prevent constipation
How does constipation occur?
When undigested material passes through the colon too slowly. This leads to too much water being reabsorbed.
What are the benefits of dietry fibre?
Fibre stimulates peristalsis in the colon and helps to prevent constipation
What are enzymes?
Biological catalysts
What are the three enzymes involved in digestion?
Amylase, Pepsin and Lipase
What is the role of salivary amylase?
To digest starch
Where is the production site of salivary amylase?
The salivary glands
Where does salivary amylase work?
In the mouth
What is the pH in the mouth, where salivary amylase works?
Alkaline, pH = 8
What is the digestion product of salivary amylase?
Maltose
What is the role of pepsin?
To digest protein
Where is the production site of pepsin?
Gastric glands in the stomach wall
Where does pepsin act?
The stomach
What is the pH in the stomach, where pepsin act?
Acid, pH = 2
What is the digestion product of pepsin?
Peptides
What is the role of lipase?
To digest fat
Where is the production site of lipase?
The pancreas
Where does lipase act?
The dudenum
What is the digestion product of lipase?
Fatty acids and Glycerol
What parts make up the large intestine?
Caecum, Colon, Appendix, Rectum, Anus
What is the definition of a balanced diet?
Taking the correct amounts of all the essential nutrients in the diet e.g. carbohydrates, proteins, fats, fibre, vitamins, minerals, water
How is a balanced diet achieved?
Eating a variety of foods and eating each food type in moderation
What does the amount of food required by someone depend on?
Age - young adults need more than older individuals
Gender - Males need more than females
Activity - More active individuals need more than less active individuals
How many food groups are there and what are they?
5 - Breads and cereals, Fruit and vegetables, Meat fish and poultry, Milk and milk products, Fats oils and alcohol
Draw a food pyramid
.
How many daily food portions of oils fats and alcohol should and adult eat?
Very few
How many daily food portions of milk products should an adult eat?
2-3
How many daily food portions of meat, fish and poultry should an adult eat?
2-3
How many daily food portions of fruit should an adult eat?
3-5
How many daily food portions of vegetables should an adult eat?
3-5
How many daily food portions of cereals, breads and potatoes should an adult eat?
6-11
