Mouth/ Oesophagus
Can you name the 4 main events in human nutrition
Ingestion
Digestion
Absorption
Egestion
What makes up gastric juice?
HCl, Mucous, Pepsinogen
What are the 3 glands we have looked at?
Liver, Pancreas, Gall bladder
Name the 2 parts of the small intestine
Ileum
Duodenum
What are the functions of the caecum and appendix?
No function! They are vestigial organs
Can you name the dental formula?
2 (I 2/2, C 1/1, P 2/2, M 3/3)
What is the role of mucous in the stomach?
Prevents self digestion
Name a location in the digestive system for lipase digests lipids
The pancreas
What is the function of the duodenum and the ileum
Duodenum: digestion
Ileum: Absorbs nutrients
What is the function of the colon?
Reabsorb water
What are the functions of each of the teeth?
Incisors: cut and slice
Canines: grip and tear
Premolars: crush and grind
Molars: Crush and grins
What is the function of pepsinogen? What is it's active form?
Active form: pepsin
Converts proteins to smaller peptides
Name 2 functions of the liver
Produces bile
Detoxifies the body
Aids in formation of urea
Stores minerals and fat-soluble vitamins
Makes cholesterol
What is the function of the villus and lacteals?
Villus: aids absorption
Lacteal: Helps to absorb fats (transports them to lymph)
What does symbiosis mean?
When at least one species benefits
Explain both types of digestion that occur in the mouth
Mechanical: chewing and grinding action of teeth on food
Chemical: occurs in the mouth by the action of the enzyme amylase. Amylase breaks down starch into maltose
What are the 3 functions of HCl?
Kills micro-organisms
Loosens food fibres
Activates pepsinogen
What is the function of the pancreas?
Produces insulin
1. Large numbers
2. Walls are only 1 cell thick
3. They have a rich blood supply
What are symbiotic bacteria?
bacteria that live in (or on) another organism involving benefit
Explain the process of peristalsis and what stimulates peristalsis
Peristalsis: wave of muscular action in the walls of the alimentary canal that moves contents along.
Fibre stimulates peristalsis
How is the stomach involved in physical and chemical digestion?
-Contraction helps churn and digest the food physically, turning it to a thick soupy mixture called chyme
- Chemical: Through HCl, mucous and pepsin
What is the relationship between the ileum and the liver?
•Capillaries from the small intestine carry nutrients to the hepatic portal vein which carries them to the liver
•The liver acts as a warehouse- storing some nutrients and releasing others
•Amino acids cannot be stored by the body- they become toxic
•The liver breaks them down and forms urea (deamination)
•Urea and other wastes leave the liver in the hepatic vein and goes to the kidney where it forms part of urine and is excreted
Name 3 adaptations of the S.I. for absorption
1. Very long
2. Numerous villi and microvilli
3. Walls are thin
4. rich blood supply
5. Each villus has a lymph supply to carry away the fats
Give 2 functions of symbiotic bacteria in the alimentary canal
Bacteria in the colon feed on waste and produce vitamins B and K, which we can then absorb from the colon
Bacteria also break down food in the digestive system, especially cellulose. Some of the digested nutrients are absorbed into the body from the intestine
The presence of such beneficial bacteria prevents the growth of disease-causing bacteria and fungi