Digestive System - Detail

Basic

Function

• cells need nutrients from our food

• processes include digestion and absorption

• gets rid of solid waste

• mainly one tube from mouth to anus called gastrointestinal tract (GI-Tract)

Organs

• mouth

• stomach

• smal/large intestine

• liver

• gall bladder

• pancreas

• rectum and anus

Definition of Digestion

The process of breaking down food into nutrients and moving it into blood

Mechanical Digestion

Large chunks of Food are broken down into small pieces. Starts with the mouth and physical processes, such as chewing.

Chemical Digestion

Large food molecules are broken down into small nutrient molecules using enzymes. Strats with the mouth and goes basically to the end. Examples include saliva digesting carbohydrates for the brain.

Definition of Absorption

• process that allows substances to enter the blood system

• blood absorbs nutrients for growth or even re-making cells

• some substances are not able to be processed so they leave the body as solid waste (called elimination)

Organs

Muscle Movement

• muscles contract or tighten to push the food through the system, wave like

• movement called peristalsis - involuntary process which is the reason why food can go through our system

• liver, gall bladder, and pancreas are the organs which no food passes through as they store or secrete enzymes which help break down the food chemically

Mouth

• seeing or smelling can cause the release of saliva in the mouth

• once you start eating saliva were and therefore helps break and swallow food

• digestive enzymes (including amylase) start breaking down starches into sugars

• tongue mixes food with saliva and enzymes

  teeth break down food mechanically by chewing it into smaller bits before your tongue helps swallow the food

Oesophagus

• uses peristalsis to move down food its self as it is just a long tube with muscles from mouth to stomach

• at the bottom there is a muscle that fully closes the path after the food has entered the stomach

Stomach

• is an organ which is sack like and uses its muscles to move the food its storing so that enzymes such as pepsin can reach every bit of food

• pepsin helps digest proteins

• water, salts and simple sugars can also be absorbed

• food stays and gets stored in the stomach until the small intestines are ready to receive it (average 3h)

• fluids mainly are hydrochloric acid

• muscles surrounds the insides of the stomach to protect other tissue from burning - can also re grow

Small Intestines

• juices from the liver/gall bladder and pancreas make the food “non acidic” in the first part called the duodenum

• from the stomach to the large intestine

• around 7 meters long in a average adult

• enzymes cut down last piece of nutrients

• later section is full of villi which are like the inner wall

• villi are like the doors for the nutrients to enter the bloodstream

• millions of trillions of villi in the small intestine creating a way larger surface area so that nutrients have a way higher chance of entering the circulatory system

• villi make the surface area around 1000 times larger

Large Intestine

• wide tube that connects the small untestine with the anus

• around 1.5 meters long in a normal adult

• the waste eneetrs still in a liquid dtate before the fluids get absorbed and drained leaving a solid which then gets passes and released through the anus and rectum, which then gets called a bowl movement

Digestive Enzymes

• enzymes are proteins that help speed up chemical reactions

• break larger food molecules in simpler ones

• released/secreted by organs in the digestive system

• types include protease that digest proteins and nucleases that digest nucleic acidic

Examples

amylase

• produced in the mouth

• breaks down large starch mollecould into simple sugars

Pepsin

• produced in the stomach

• breaks down proteins into amino acids

Pancreatic lipase

• produced in the pancreas

• digests lips and fats

Deoxyribonuclease and Ribonuclease

• produced in the pancreas

• break down bonds in nucleic acids like DNA and RNA

trypsin

• produced in the pancrease

• breaks down protein in the small intestines

Bile

• Bile salts are acids that break down fats and lipids

• bile acids are made in the liver and get stoard in the call bladdr

• when eating, bile gets released/secreated into the small intestine

Hormones and Digestion