Alimentary system & Digestion Flashcards
(25 cards)
List the functions of the digestive system
Ingestion, mastication, secretion, digestion, absorption, elimination, mixing, propulsion
How is the digestive tract different from the digestive system?
The digestive tract is only the tube extending from the mouth to the anus.
The digestive system includes accessory organs as well.
What are other names for the digestive tract?
Alimentary tract, alimentary canal
What does the term ‘gastrointestinal tract’ technically refer to?
Only the stomach and the intestines, but is often a synonym for ‘digestive tract’
Name the organs in the digestive tract, with their accessory organs
Oral cavity (salivary glands) Phaynx (tonsils) Oesophagus Stomach Small intestine (liver, gallbladder, pancreas) Large intestine Anus
What are the two types of digestion?
Mechanical and chemical
Mechanical digestion
Physical disruption of food into smaller parts
Chemical digestion
Breakdown into small soluble constituents
Reliant on enzymatic action
Some enzymes are produced by the body, others are produced by commensal bacteria
Digestion carried out by commensal bacteria is referred to as fermentation
Mechanical digestion in the oral cavity
Chewing / mastication
Physical break up of food
Chemical digestion in the oral cavity
Saliva from salivary glands contains salivary amylase for carbohydrate digestion
Name the three largest salivary glands
Parotid, Sublingual, Submandibular
What’s the main function of salivary glands?
They make saliva, which is a combination of serous and mucous secretions from all the salivary glands
What does the oesophagus do?
It transports food from the pharynx to the stomach
The oesophagus is lined with stratified squamous epithelium – what function does it have?
It protects against mechanical abrasion
What are the four main layers in the oesophagus wall?
Stratified squamous epithelium
Submucosa layer (with mucous glands)
Muscular layer (outer longitudinal muscle, inner circular muscle)
Adventitia
Mechanical digestion in the stomach?
- Churning and mixing of food
* Increases contact between enzymes and digesta
What gets released in the stomach to aid with chemical digestion?
- Pepsinogen
- Hydrochloric acid
- Rennin/Chymosin
What does pepsinogen do?
It gets converted into pepsin, which digests protein
Why is hydrochloric acid released?
It promotes pepsin activity and kills microorganisms
Why is rennin important?
It breaks down casein in milk products.
What are the three muscle layers in the stomach?
Outer - longitudinal
Middle - circular
Inner - oblique
What are rugae?
Gastric folds in the inner layer of the stomach. Present in an empty stomach and disappear when distended
What are the functions of the rugae?
Rugae both allow the stomach to stretch in order to accommodate large meals and help to grip and move food during digestion.
What are mucosa?
Simple columnar epithelium with gastric pits
