Digestive System

Question 1

Purpose

Answer 1

To turn food into absorbable nutrients needed to survive

Question 2

Key points

Answer 2

Ingestion- for entering the body
Chemical digestion - the chemical breakdown of food molecules
Mechanical digestion - the physical breakdown of food pieces into smaller pieces
Peristalsis - movement of food along the alimentary canal, muscle contraction and movement
Absorption - the movement of food into the body, from the alimentary canal into capillaries in the wall of the small and large intestine
Elimination - the removal of non-absorbed ingested food from the body

Question 3

Alimentary canal

Answer 3

Tube that runs from the mouth to anus

Contains - mouth, oesophagus, stomach, small intestine and large intestine

Question 4

Mouth

Answer 4

Ingestion occurs mouth

Different types of teeth are used to break food down - mechanical

Saliva and salivary glands are there for chemical breakdown of food - chemical

Tongue allows food to be moved around the mouth and swallowed

Epithelial tissue on the surface of the mouth is thin, repairs quickly and replaces itself frequently

Question 5

Oesophagus

Answer 5

2 layers of muscle underneath the epithelial tissue

Circular - horizontal layer
Longitudinal - vertical layer

Peristalsis - muscle contracting in a wave-like motion, forcing food through the digestive tract

Epithelial cells secrete a mucus that assist in lubricating the oesophagus to allow food to move along it more easily

Question 6

Stomach

Answer 6

3 layers of muscle under epithelial cells
Has circular and longitudinal muscle like the oesophagus but also has the,

oblique muscle, allowing food to be churned in variety of direction

The lining of stomach is wrinkled this both increases surface area and allow for expansion of the stomach

Epithelial muscle protects stomach

Question 7

Small intestine

Answer 7

6 meters in length but smaller diameter then other intestine

Absorption of almost all nutrients occurs here

Combination of muscular and epithelial tissue allows for absorption, peristalsis and increase in surface area

Mucosa (lining) maximises SA as it is folded

Mucosa is covered by villi (finger like projections of epithelial tissue containing a capillary bed

Epithelial cells of the villi are covered in microvilli - designed to maximise SA for absorption

Question 8

Large intestine

Answer 8

Wider diameter but only 1.5m long

Epithelial lining secretes mucus to allow faeces to move along more easily - no villi and microvilli

Material spends up to 24 hours in the large intestine ; the primary purpose of the large intestine is water reabsorption

Question 9

Accessory organs

Answer 9

Organs that facilitate the digestive system that are not apart of the alimentary canal

Liver - produces bile to emulsify fats/ detoxifies alcohol/ filter blood

Gall bladder - stores the secretes into the stomach - mechanical digestion

Pancreas - secretes enzymes involved in chemical digestion into duodenum and small intestine