AMouthB

B

Salivary gland

Salivary glandsPharynxC

DEpiglottis

EOesophagus

StomachFLiverGGall bladder H

IPancreasJDuodenum

KSmall intestineLColon

MCaecum

NAppendix

Large intestineORectum

P

QAnus

Mouth

• Mechanical breakdown of food

• Saliva – lubrication

• Salivary amylase – breakdown of starch and carbohydrates

• Tongue – gathers food in to a bolus

Oesophagus

• Entry regulated by epiglottis

• Soft muscular tube

• Moves food through rhythmic muscular movement called peristalsis

• DEMONSTRATION

Stomach

• Can expand from an empty volume of 50ml to a full volume of 1.5 L

• Gastric juices are a mixture of mucouse, enzymes, hydrochloric acid and water

• Pepsin – breaks down proteins• Muscular contractions – further

mechanical breakdown• Hormones secreted to pre-warn pancreas

and gall bladder of incoming chyme

Pancreas

• Creates enzymes and other products and secretes them in to the common bile duct:

• Bicarbonate – neutralise stomach acid

• Amylase – continue breakdown of carbs

• Protease – continue breakdown proteins

• Lipase – breaks down lipids

• Nucleases – breaks down DNA, RNA and cellular organelles

Liver & Gall Bladder

• The liver secretes bile (greenish fluid containing bile salts, cholesterol & pigment) in to common bile duct.

• Bile stored in gall bladder if no digestion is taking place.

• Bile salts emulsify fat (break it in to smaller droplets (eg milk & detergent)

Pancreatic disorders – Cystic Fibrosis

• A CF patient’s blocked pancreatic duct

• The amount of enzyme replacement capsules required to be taken every day

Small Intestine

• Composed of the duodenum, jejunum and ileum• Food spends 3 to 6 hours here• Around 90% of absorption of nutrients takes

place here• Surface area is greatly increased by entire inner

lining covered in villi, and each of these villi covered in microvilli.

• Also approx. 8.5L of water is absorbed from food daily.

Villi

• Each villus has a huge network of capillaries running through it.

• Absorption of nutrients is by means of diffusion and active transport.

Large Intestine

• Composed primarily of the colon, caecum and the rectum

• Any undigested food gets further processed by bacterial breakdown

• Another 0.5L of water is reabsorbed daily

• Waste called faeces (undigested food, water, dead cells & bacteria) passes out of the rectum through the anus.

Flatus

• A gas called flatus also passes through the anus, it is the result of swallowed air or gas produced during bacterial breakdown