SACE Stage 1 - Digestive System

Journey

Mouth > Oesophagus > Stomach > Small Intestine > Large Intestine > Rectum > Anus

Mechanical Digestion

Breaks apart food which increases surface area for chemical digestion (e.g. chewing)

Chemical Digestion

Process by which enzymes break down food into small molecules that the body can use

Digestion in Mouth

Mechanical:
- chewing to break apart food
- tongue moves food around

Chemical:
- salivary glands produce saliva in mouth

Digestion in Oesophagus

No chemical or mechanical digestion occuring

Perisatalsis

Wave-like contractions of muscle that pushes the bolus down to the stomach

Bolus

Chewed up food

Digestion in Stomach

Mechanical:
- churning of stomach moves to break apart food for an increased surface area

Chemical:
- helps kill some bacteria that can't withstand 2-3 pH (of HCl)
- activates the enzyme protease, which breaks down protein

Chyme

Pulpy, acidic fluid which passes from stomach to small intestine

Goblet Cells

Secretes main components of mucus

Primary Organs

Organs where food travels through (e.g. mouth oesophagus, stomach, small intestine, large intestine, rectum and anus)

Secondary Organs

Organs where food does not travel through and is a vital part of digestion (e.g. liver, gallbladder and pancreas)

Liver and Gallbladder Digestion Process

Bile is produced in the liver and then stored in the gallbladder. Bile is transferred into the duodenum of the small intestine. Bile aids in the emulsification of lipids breaking them apart into goblets. Bile also neutralises the acid from the stomach

Pancreas

No mechanical digestion occurs here.

Chemical digestion:
- pancreas produces digestive enzymes and trasnports them into the duodenum of small intestine

Lipase

Breaks down lipids into fatty acids and glycerol

Protease

Breaks down protein into amino acids

Pancreate Amylase

Breaks down carbohydrates into glucose

What Occurs In Duodenum?

Chyme mixes with bile from liver and pancreatic juice from the pancreas to complete digestion

What Occurs In Jejunum?

Nutrient absorption

What Occurs In Ileum?

Completes nutrient absorption missed in the jejunum

Function of Lipase

Breaks down lipids into fatty acids and glycerol

Bile

From liver, helps digestion

Lacteal Function

Absorbs digested food (e.g. glucose, amino acids, fatty acids, glycerol)

Where Are Carbohydrates Digested?

Mouth and Duodenum

Which Enzymes Break Down Carbohydrates?

Amylase and Pancreatic Amylase

Product of Carbohydrate Digestion

Glucose

Where Is Carbohydrate Abosrbed In Vili?

Blood capillaries

Where is Protein Digested

Stomach and Duodenum

What Enzymes Break Down Protein

Protease

Product of Protein Digestion

Amino Acids

Absorption of Protein in Villi

Blood Capillaries

Where Are Lipids Digested?

Duodenum

What Breaks Down Lipids

Bile and lipase

Product of Lipid Digestion

Goblets, fatty acids and glycerol

Absorption of Lipid in Villi

Lacteals

Lacteals

Transports fatty acids and glyerol away from the small intestine

Large Intestine

Peristalsis moves the indegistible waste to the rectum and then the anus

Water reabsorption occurs here