Digestive System

Question 1

Parts required for digestion

Answer 1

A= Mouth - Ingestion/Mechanical digestion
B= Oesophagus - Food molecules are transported
C= Stomach - Chemical digestion
D= Small intestine - Absorption/Assimilation
E= Large intestine - Absorption
F= Anus - Egestion

Question 2

Ingestion description?

Answer 2

Ingestion:
Food entering the body
Mostly occurs in the mouth.
Salivary amylase helps break down food molecules
Peristalsis: Muscles behind the food contract while the muscles in front of the food relax. This moves food along the oesophagus.
Circular muscles and longitudinal muscles take turns to contract and relax to move food along.

Question 3

Digestion description?

Answer 3

Large insoluble molecules are broken up into small water soluble molecules so they can be absorbed by the bloodstream.
Occurs mechanically and chemically
Once it reaches the stomach, the stomach acids break down the food molecules further.
In the small intestine, the food molecules are mixed with digestive enzymes from the pancreas and bile from the liver.

Question 4

Mechanical digestion?

Answer 4

Breakdown of large pieces of food into smaller pieces without changing the food molecules.

Question 5

Chemical digestion?

Answer 5

Chemical digestion breaks large molecules into smaller molecules by action of enzymes,

Question 6

Absorption description?

Answer 6

Digested molecules go through the wall of the small intestine to the blood.
Food particles like glucose/amino acids pass through villi of the small intestine to diffuse into blood. Digested food then reaches the capillaries and lacteal (lymph capillaries) in the villi and the absorbed molecules are transported to the liver through the hepatic portal vein.

Question 7

Adaptations of the villi

Answer 7

Large Surface Area
More surface area for absorption
Thin Walls
Shorter diffusion path ( one cell thick)
Moist Lining
Assist transporting because gases dissolve in moisture.
Rich blood supply
To absorb and carry dissolved food molecules.
Many villi
There are many villi in the small intestine which means diffusion is happening a lot and everywhere which makes it more efficient.

Question 8

What are villi?

Answer 8

Villi are finger-like projections that are an adaptation for efficient absorption.

Question 9

Assimilation description?

Answer 9

Soluble food molecules are used to make new cells or parts of cells.

Question 10

Egestion description?

Answer 10

The passing of indigestible (faeces) food through the anus.