Digestive system Flashcards
Definition of the digestive system
The organ system including the mouth, teeth, tongue, oesophagus, stomach, intestines and various glands that function together to ingest, digest and absorb nutrients
Digestive Process Digestive Process 6
- Ingestion
- Secretion
- Mixing & Propulsion
- Digestion
- Absorption
- •Defecation
Saliva consists of
•Saliva consists of :- Water, Mineral salts, mucus, immunoglobulins, blood clotting factors and the salivary enzymes
Tongue
Is a muscular organ which is attached to the hyoid bone and the mandible.
Functions :- 4
- Organ of taste
- Assists in mastication
- Assists in swallowing
Assists in speech
The Oesophagus
•A soft muscular tube [flat] 25 to 30cm long
•
•Runs down the gap in the “C” shaped rings of the cartilage surrounding the trachea and passes through the diaphragm at the level of the 10th thoracic vertebra to become the stomach
•
•The oesophagus, moves the bolus of food towards the stomach by “Peristalsis”
The Stomach
•The stomach is the most dilated part of the digestive system, and it can hold up to 1500ml in the adult
•
•The upper opening of the stomach is called the cardiac sphincter
•
•The lower opening of the stomach is called the pyloric sphincter
The fundus of the stomach lies where
The fundus of the stomach lies in the left upper quadrant of the abdomen just inferior to the diaphragm
•Food is mixed with gastric juices which contain hydrochloric acid and an enzyme that begins the digestion of food (Chemical Digestion)
•
•A lining of mucus prevents the walls of the stomach being digested by the enzyme
•
•The function of the stomach is to churn up the food (Mechanical Digestion) into a milky substance called “chyme” by mixing it with gastric juices
Amylase = turns starch into sugars (mouth & small intestine)
Protease = proteins into amino acids (stomach & small intestine)
Lipase = Lipids into fatty acids + glycerol (small intestine)
All produced in Pancreas and where they are working
Gastric Juice
Secreted by special glands in the mucosa and consists of
- Water
- Mucus
- Hydrochloric acid
- Enzymes
Functions of Gastric Juices
- Gives acid reaction required by the enzymes
- Kills bacteria
- Stops the action of Amylase
•
•After 2-6 hours the chyme is passed through the pyloric sphincter into the duodenum
The small intestine
•Is continuous with the stomach at the pyloric sphincter and leads into the large intestine
•
•It is a little over six metres long and lies in the abdominal cavity surrounded by the large intestine
The small intestine
•In the small intestine the chemical digestion of food is completed and most of the absorption of nutrient materials takes place
•
•The small intestine is described in three parts, which are continuous with each other
Duodenum
•Approx. 25cm long, it curves around the head of the pancreas.
•
•At its midpoint there
is an opening –common
to the pancreatic duct
and the common bile duct
•
•The bile, pancreatic and intestinal juices complete the conversion of the chyme into fats, amino acids and carbohydrates
Jejunum and Ileum
•The jejunum is the middle part of the small intestine and is about two metres long. It’s continuous with the….
•
- Ileum or terminal part, which is about three metres long
- Ends at the ileocaecal valve which controls the flow of material from the ileum to the large intestine and prevents regurgitation
Function of Small Intestine
5
1.Onward movement of its contents which is produced by peristaltic movements
●2.Secretion of intestinal juice
●3.Completion of digestion of carbohydrates, fats and proteins in the epithelial cells of the villi
●4.Protection against infection by microbes that have survived the antimicrobial action of the hydrochloric acid in the stomach
●5.Absorption of nutrient materials
Functions of Large Intestine
