Gastrointestinal System: Structure & Function

A network of organs and specialised cells that enables you to transform the food you eat into the energy and nutrients required for life.

Mouth Oeophagus Stomach Small intestine Large intestine Anus

Salivary glands Liver Gallbladder Pancreas

Membranous tissue Surrounds organs of the GI tract Holds intestines in place Provides blood vessels and lymphatics

Teeth Tongue Mucous membranes Main function is to chew food Pharynx andepiglottis Prevent food travelling to the lungs

Tube like structure Involuntary movement of food bolus Transports food bolus to stomach

Mixing Protein digestion HCl, Pepsin Fat emulsification different section esophagus cardia fundus body pylorus pyloric sphincter duodenum

Longest part of the GItract Main site of absorption Divided into 3 sections

Paneth cells - defensins - antimicrobial - lysozymes - phagocytic Stem cells – regeneration Gobletcells - mucous

water and ion conservation bulk movement of faeces storage defaecation

Lubrication - mucus Protection – thiocyanate, lysozymes Digestion Amylase Lipase

Bile productionandexcretion

Concentrating reservoir for bile Delivers bile to the duodenum in response to meals.

Makes enzymes to digest proteins, fats,and carbohydrates Produces the hormones insulin and glucagon

ingestion secretion movement digestion absorption excretion

Ingestion - the process of taking in food, or drink, through the mouth.

Secretion – the release of substances that contribute to digestion.

Segmentation- contract and relax Peristalsis- contract and puch froward

Digestion - breakdown of food into smaller components that can be absorbed into the bloodstream. - Mechanical digestion - Chemical digestion

Physically breaking down food substances into smaller particles mastication peristaltic contractions gastric acids

Use of enzymes to breakdown food: Fats → fatty acids and monoglycerides Nucleic acids → nucleotides Polysaccharides or carbohydrate sugars → monosaccharides Proteins → amino acids Secreted by accessory organs

Absorption – the process through which nutrients, water and electrolytes enter the blood.

Excretion- the process by which metabolic waste is eliminated from the body

The GI system is important as it transforms the food you eat into theenergy and nutrientsrequired for life The main organs of the GI system include the mouth, oesophagus, stomach, small intestine and large intestine There are 6 main functions of the GI system: ingestion, secretion,movement, digestion, absorption, excretion and immune function Ingestion occurs in the mouth Movement occurs in the mouth, oesophagus, stomach, small intestine and large intestine Digestion occurs in the mouth, stomach, small and largeintestine Absorption occursin the small and large intestine Excretiontakes place in the large intestine The large intestine is involved in immune function