Organisation and the digestive system
Organisation and the digestive system
Why do we need to digest food?
Tissues and organs
Different organ systems
Motor neurone - Nervous tissue - Spinal cord - Nervous system
Alveoli cell - Alveolus - Lungs - Respiratory system
Bone cell - Compact bone - Bone - Skeletal system
Sperm cell - Testis tissue - Testis - Reproductive system
Palisade cell - Palisade layer - Leaf - Leaf system
Endothelial cell - Blood vessel lining - Blood vessels - Circulatory system
Smooth muscle cell - Smooth muscle - Small intestine - Digestive system
An example of an organ is the stomach
Tissues that the stomach contains are muscular tissue, epithelial tissue and glandular tissue
cell -> tissues ->organs ->organ systems ->organisms
What are they
A tissue is a group of cells with a similar structure
Organs are groups of tissues performing similar functions. They're organised in organ systems which work together to make organisms.
Human digestive system and digestive enzymes
What is it
The digeative system is between 6 to 9 metres long. It is a long muscular tube which sqeezes food along by a wave of muscular motion called peristalsis. Glands such as the pancreas and salivary glands produce proteins called enzymes to break down food into smaller, soluble molecules which can be absorbed and used by cells.
Parts of the digestive system
8:Liver-This is a large meaty organ which sits on the right side of the stomach. It secretes bile which digests protein and emulsifies fat to make them easier to break down and absorb.
7:Pancreas-This is a large gland behind the stomach next to the small intestine and it releases trypsin and peptidase to aid the breakdown of proteins.
10:Bile duct-This tube carries bile from the gall bladder through the pancreas, while adding pancreatic juices, and into the small intestine.
6:Duodenum-The beginning of the small intestine. It receives partially digested food and prepares it to be absorbed in the small intestine.
11:Small intestine-This is where most of the food is absorbed into the blood stream. It splits into 3 parts: the duodenum, the jejunum and the ileum.
5:Stomach-A muscular organ which secretes gastric juices and hydrochloric acid to digest food from the oesophagus. It is located in the upper left abdomen
12:Large intestine-This tube is on the outside of the small intestine and is shorter and wider. It absorbs any remaining water and salt.
4:Diaphragm-A sheet of muscle which separates the thorax from the abdomen.
13:Appendix-The function of he appendix is unknown. One theory is that the appendix is a storehouse. for good bacteria to help the digestive system after having diarrhoea.
3:Oesophagus-This is a long muscular tube connecting the mouth to the stomach,which is around 25 cm long in an adult, also known as the food pipe or gastro-intestinal tract.
14:Rectum-The rectum is a large hollow tube at the end of the large intestine. It stores faeces or waste.
2:Salivary glands-these produce saliva woth amylase., an enzyme that breaks down carbohydrates.
15:Anus-The end of the digestive system where wast matter leaves.
1:Mouth-The beginning of the digestive system used to break down food into smaller molecules .
9:Gall bladder-This is a pear-shaped, hollow structure under the liver. It stores and concentrates bile before releasing it through the bile duct.
Proteins, lipids and carbohydrates.
What are they
Proteins are used for building up cells and tissues in your body as well as the basis for all enzymes.Between 15-16% body mass is protein. Protein-rich foods include meat, fish, pulses and cheese and they include carbon, hydrogen, oxygen and nitrogen.
Proteins are made of long chains of amino acids. There are 20 different types and they are joined by special bonds. Different arrangements of various amino acids give different proteins.
Proteins carry out different functions in your body. They act as: structural components of tissue such as muscles and tendons, hormones such as insulin, antibodies, a key part of the immune system which destroys pathogens and enzymes, which act as catalysts.
Lipids are fats and oils. They are the most efficient energy store our bodies and the most important energy source in our diet. Combined with other molecules, lipids are important in cell membranes, hormones and the nervous system. They contain carbon, hydrogen and oxygen and they are insoluble in water.
Lipids are made up of 3 molecules of fatty acid joined to a molecule of glycerol. Lipid-rich foods include all the oils as well as butter, margarine, cheese and cream. The combination of fatty acids determine whether the lipid is a liquid oil or a solid fat.
Some contain only one unit and are known as glucose while others have two and are known as sucrose. They are known as simple sugars. Complex carbohydrate units such as starch or cellulose are made of chains of sugar units.
Carbohydrate rich foods include bread, potatoes, rice and pasta. Most of the carbohydrates eaten will be broken down to glucose used in cellular respiration.
Carbohydrates provide us with fuel for all chemical reactions needed. They contain carbon, oxygen and hydrogen and are made up of units of sugar.
Biuret test - blue Biuret reagent turns purple if protein is present.
Ethanol test - ethanol added to a solution gives a cloudy white layer if a lipid is present. Ethanol is highly flammable and harmful.
Iodine test for starch - yellow-red iodine solution turns blue-black if starch is present.
Benedict's test for sugars - blue Benedict's solution turns brick red on heating if a sugar such as glucose is present.