The Digestive System
The Mouth
The Stomach
Small Intestines
Here the food is ingested
Saliva: A mixture of mucous and serous fluid
Functions:
Dissolving food for Taste and Digestion
Mucos: Mostions food, lubricates oral surfaces
CI- Ions activate the Amalyse
Saliva contains salivary amylase, which is important when it comes to breaking down Carbohydrates (like starches)
Mechanical Digestion: Teeth mash the food together into a ball. Making the food easier to swallow.
Chemical Digestion: Amylase begins to break down starches and carbohydrates
Produced by the Salivary Glands. There are three pairs.
Composition of Saliva differ per each pair.
- Partoid Glands: Watery Saliva, Amalyse
- Sub-mandibular Glands: Thicker Mucose, Amalyse
- Sublingual Glands: Mostly Muscos, little Amalyse
Aids in Mastication (Chewing)
FUNCTION
Food breaks down into smaller fragments - Chyme
Peristalsis Occurs
Pylorus lets out Chyme into the small intestines
Esophagus
Runs from the Pharynx to the stomach
The Pharynx and the esophagus are passageways for the food.
4 Layers within the wall
Peristalsis Occurs: involuntary constriction and relaxation of the muscles of the intestine. Pushing the contents of the canal forward. (MOVEMENT)
There is a sharp transition from non Keritonizied stratified squamous to simple columnar epithelium when it meets the stomach
ANATOMY
The stomach is seperated into 3 parts:
The Fundus: Top portion of the stomach. Where the stomach meets the esophagus
The Body: Middle portion of the stomach
The Antrum of the stomach: Bottom portion of the stomach, where the stomach connects/meets the duodenum
Mucosa
Goblet cells produce alkaline mucus
Mucus surface layers trap a bicarbonate fluid beneath it
Gastric Pits
Mucus Neck Cells: Secrete mucus
Parietal Cells: Secrete HCL and intrinsic factor
Chief Cells: Produce pepsinogen and is activated by HCL in the stomach
Rugae: Folds of the mucosa
Storage Tank: Volume of 50ml to 4L
Liver
Pancreas
Controls blood glucose levels of the body: Insulin and glucagon
Produces digestive enzymes to break down food secreted into the duodenum
Produces and Excretes Bile- Emulsifies fat to aid enzymatic breakdown
LARGEST Internal organ and gland in the body
Pancreatic Juice: Contains water, salts, sodium bicarbonate, and enzymes that can digest foods of all types.
Secretion stimulates the secretion of bicarbonate. Without this we would burn holes through out intestines.
Metabolizes fats, protiens and carbohydrates
Detoxification and purification of the blood
Storage of glycogen, vitamins, and minerals
Segmentation: Mixing of chyme and juices
Peristalsis- Movement
Absorbs mineral essential nutrients
ANATOMY
1st section: Duodenum- bile duct empties secretions into the small intestine
2nd Section: Jejunum
3rd Section: Ileum
Process
Ingestion: Voluntary movement of the food into the mouth
Absorption: End products of digestion are adsorbed into blood of lymph
Defecation: Elimination of undigestible substances as feces
Digestion
Mechanical
Chemical
Churning of food in the stomach
Segmentation/Mixing inside of the small intestine
Mastication/Chewing: Grinding and mixing of food in the mouth by teeth and tongue
Carbohydrates: Broken down into simple sugars by Amylase
Proteins: Broken down to simple sugars
Enyzmes break down food molecules into small units
Fats: Broken down into fatty acids and glyceol