digestive system Flashcards
digestive system
Digestive system is the system that breaks down the food taken into the body ready for absorption into the cells.
what do body cells need
simple sugars, amino acids, fatty acids, vitamins, minerals and water to function properly
Vitamins, minerals and water in the form of small molecules are able to pass through the differentially permeable membrane of the cell
what is digestion
the process by which carbohydrates, proteins and fats are broken down into products small enough to be absorbed into the blood and to the cells. It is the mechanical and chemical breakdown of food to small molecules that can be absorbed into the body.
simple sugars, fatty acids and amino acids are eaten as complex carbohydrates, proteins and fats. These molecules are large and must be broken down into smaller units before being absorbed into the cells.
what are the activities of digestion
Ingestion of food and water
Mechanical digestion of food
Chemical digestion of food
Movement of food along the alimentary canal
Absorption digested food and water into the blood and lymph
Elimination of material that is not absorbed
mouth cavity
mechanical digestion by teeth
chemical digestion of starch by salivary glands
pharynx
back of mouth cavity by moving up wards
throat that joins the mouth cavity to the oesophagus and larynx.
mechanical digestion
mechanical breakdown of food into smaller particles
chemical digestion
chemical breakdown of food into small molecules
saliva
fluid that is secreted into the mouth cavity by 3 pairs of salivary glands to begin digestion. It contains a mucous and digestive enzyme, salivary amylase, which begins the chemical digestion of starch, breaks down large starch molecules into smaller molecules.
how does ingestion occur in mouth
The action of jaw and teeth begins mechanical digestion, where food is broken into smaller products
Ingestion is the intake of food, liquids or drugs into the mouth.
what are the teeth made of?
4 incisors - chisel shaped teeth that are used for biting or cutting, like taking a bite out of an apple
2 canines - one on each side of the incisors. Conical teeth used for tearing. Same length as the other teeth, carnivorous animals have longer canines for tearing
4 premolars - 2 on each side of the jaw
6 molars - 3 on each side of the jaw.
same number occurs at top
oesophagus
tube 23-25cm that carries food from the throat (pharynx) to the stomach.
what is the oesophagus made of?
double layer of muscles, longitudinal an circular muscle
what is longitudinal muscle?
smooth muscle with fibres arranged lengthwise across an organ
smooth muscle
smooth muscle with fibres arranged in a circle around the organ (alimetnary canal in this case)
what is the stomach
what are the muscles of the stomach?
roughly j shaped enlarged section of the alimentary canal
mechanical digestion by churning action, waves of muscular contractions. chemical digestion by pepsin which begins protein digestion in infants, rennin coagulation milk protein.
contract in a variety of different ways to churn the food and mix it with the gastric juices, until food is converted into thick, soupy liquid called chyme.
longitudinal, oblique, circular.
what is the pyloric sphincter
band of circular muscle that regulates follow of material from the stomach to duodenum.