Components of Digestive system

digestion def

process of breaking down carbohydrate, protein and fat molecules into products small enough to be absorbed into blood and cells

mechanical

physical breakdown of food into smaller pieces to increase SA

chemical

use of enzymes to break down large complex molecules into smaller simpler molecules so it can be absorbed into bloodstream

alimentary canal

continuous tube that runs from mouth to anus

alimentary canal lining

surface where nutrients are absorbed

associated organs func

aid in digestion but does not actually transfer food

functions of digestive system

- INGESTION of food and water

- MECHANICAL digestion of food

- CHEMCIAL digestion of food

- MOVEMENT of food along alimentary canal

- ABSORBPTION of digested food and water into blood and lymph

- ELIMINATION of material not absorbed

mouth, teeth, salivary glands, tongue

site of ingestion

mouth, teeth, salivary glands, tongue M

mastication by jaw and teeth

- break down food into smaller pieces

- increase SA:V ratio

mouth, teeth, salivary glands, tongue C

mixed with saliva which contains mucus and enzymes that break down starch

tongue

aids swallowing

- moves upwards and backwards

- pushes bolus to back of mouth, pharynx, oesophagus

oesophagus length

23-25 cm

oesophagus what

tube that connects pharynx to stomach

oesophagus wall

double layer of muscle wall

oesophagus double muscle wall comp

- circular muscle

- longitudinal muscle

oesophagus transport

peristalsis

Peristalsis

contraction of circular muscle pushes down to stomach

stage 1 peristalsis

- circular muscle behind bolus contracts

- circular muscle around and in front relax

stage 2

wave of contraction of circular muscles move along oesophagus pushing food infront

movement of bolus help!

lubricated by mucus from lining

stomach what

enlarged section of alimentary canal where food undergo M and C digestion

stomach internal surface

covered by thick layer of mucus (no absorption)

stomach M

contraction of stomach in several ways due to extra layer of muscle

stomach extra layer of muscle

third layer called oplique

rugue

folds in stomach which increase SA

stomach C

glands produce gastric juice

gastric juice comp

- pepsin

- gastric lipase

- HCl

pyloric sphinctor

thick band of muscle that acts like valve

small intestine length

longest part of alimentary canal, 6-7 m

small intestine func

receives material pushed through pyloric sphincter from stomach

duodenum

chemical digestion aided by pancreatic enzymes

jejunum

allow absorption of carb and protein

ileum

remainder of digestion products absorbed

regions in order small intestine

- duodenum

- jejunum

- ileum

large intestine length

1.5 m

large intestine made up of

caecum with appendix, colon, rectum and anus

large intestine lining

large amounts of mucus secreted by lining

large intestine absorb

most of remaining water

large intestine presence

bacteria

bacteria fun

- aid chemical digestion

- some produce vitamins

faeces

semi-solid material left after water absorption and bacterial action