Structure & Function of Digestive System Flashcards
What is digestion?
The process in which carbohydrates, protein, and fat molecules are broken down to products small enough to be absorbed into the blood and into the cells.
Why must molecules broken down?
Simple sugars, amino acids and fatty acids are eaten as complex carbohydrates, proteins and fats. These large molecules are broken down before they can be absorbed by cells
What is the function of the digestive system?
The digestive system extracts nutrients from the food we eat and absorbs them into the body for use by the cells.
What functions do organs of the digestive system carry out?
- Ingestion of Food and Water
- Mechanical and Chemical Digestion of Food
- Movement of Food along the Alimentary
- Canal Absorption of Digested Food and Water into the Blood and Lymph
- Elimination of Material that is Not Absorbed.
What is the alimentary canal?
The continuous tube that runs from the mouth to the anus.
Makes up the digestive system together with associated organs such as the pancreas and gall bladder.
The lining is the surface through which nutrients are absorbed
What is the function of the mouth cavity?
- Ingestion (intake of food)
- Mastication
- MD by teeth
- CD of starch by saliva before food is swallowed
What is mastication?
When food is chewed and broken down into smaller pieces.
What is the function of the salivary glands?
They produce saliva which dissolves food so it can be tasted.
What is the purpose of saliva?
It contains mucus that lubricates the mouth and holds food in a lump for swallowing.
Also contains the salivary amylase, which begins the chemical digestion of starch
What is the function of the liver?
Produces bile, which is stored and concentrated in the gall bladder.
Bile emulsifies lipids in the small intestine.
What is the function of the gall bladder?
Stores bile and releases it into the small intestine, where the bile emulsifies lipids
What is the function of the duodenum?
The first part of the small intestine where most of the chemical digestion occurs before the chyme moves further along the small intestine.
What is the function of the colons?
It absorbs water, minerals and vitamins.
What is the caecum?
First part of the large intestine.
It is a pouch, about 6cm long, where the small intestine joins the large intestine.
What is the function of the appendix?
A small tube attached to the caecum that plays a role in immunity and stores useful bacteria.
What is the function of the rectum?
The final part of the large intestine in which faeces are formed.
Material left in the colon after water absorption is pushed into the rectum by peristalsis so it can be passed out
What is the anus?
The external opening at the end of the rectum surrounded by the anal sphincter, a circular muscle that can be voluntarily controlled.
What is the function of the small intestine?
About 6m long, it receives material pushed through the pyloric sphincter from the stomach.
The internal surface is lined with villi for absorption of digested food.
Its lining secrets intestinal juice, which contains many enzymes.
What are the three regions of the small intestine?
Duodenum, Jejunum and Ileum
What is the Jejunum?
The middle section of the SI
The lining of the jejunum allows effective absorption of carbohydrates and proteins
What is the Ileum?
The final part of the small intestine
Vitamin B12, bile salts, and any remaining products of digestion are absorbed.
What is segmentation?
Mechanical digestion occurs in the SI.
Contractions of the circular muscles narrow the intestine helping break up the bolus and mix it with the juices and bile.
What is the function of the pancreas?
It produces pancreatic juice containing enzymes that digest proteins, lipids, and nucleic acids and enters the duodenum through the pancreatic duct
Contains powerful enzymes that break down all types of nutrients.
How does the Pancreas maintain a basic ph?
Contains bicarbonate ions, which maintain a basic ph of around 8
