The Digestive Systems Flashcards
What is the Cells to Systems order?
Cells, Tissues, Organ, System, Organism
What do animals (heterotrophs) need for digestion?
- Ingestion of food
- Mechanical breakdown of food
- increase the SA:V
- Secretion of digestive enzymes onto the food
- Absorption of digested food
- transport/diffusion of food particles into extracellular fluid
What is the digestive system assembly line?
- Mechanical digestion
- Chemical Digestion
- Absorption
- Elimination
Brief overview of Mechanical vs Chemical Digestion
Mechanical digestion: Food is broken down into smaller pieces, No change in the chemical nature of the food
Chemical digestion: Chemical nature of the food changed by enzymes, Produces smaller molecules that can be absorbed by the blood
What role does saliva have in food digestion?
Saliva has amylase, which being starch digestion
Saliva also dissolves some food, which stimulates tongue tastebuds and allows for food flavour recognition and detection
What is the oesophagus?
The tube that transports food from the mouth to the stomach by peristalsis.
(Peristalsis is the contraction of muscle walls to move food from mouth to stomach)
What happens in the stomach?
Food enters stomach, stomach secretes gastric juice which is a mix of mucus and enzymes (pepsin)
Pepsin acts on peptide bonds between amino acids and digestion of protein begins
Stomach part 2 (During digestion)
Hormones are produced in the cells of the stomach wall, the hormones signal to the pancreas and gall bladder that food is in stomach and will enter small intestine
Bile causes the emulsification of lipids and fat, increases SA:V (Mechanical digestion)
Stomach part 3 (What is it?)
Temporary storage tank, where food is mixed through churning
Digestive juices are released by membrane to make an acidic environment
Peristalsis of the stomach pushes food along to the small intestine
What is the Liver? And what does it do?
It is the larges gland in the body
Produces bile, secretes it into the small intestine
Bile salts emulsify fats, facilitate fat digestion
What does the gall bladder do?
Stores excess bile
What does the pancreas do?
Secretes pancreatic juice into the small intestines
Contains many enzymes that act on starches, proteins and fats
What does the small intestine do?
Digestion of proteins, carbs and fats take place (mostly in the duodenum)
Bicarb in secreted by the pancreas to neutralise chyme by increasing it’s pH
What else does the small intestine do?
Has trypsin
Absorption happens, majority of it the jejunum and ileum
Much of this absorption is by diffusion, against a concentration gradient into an area that already has a high concentration of that material
What are the 3 sections of the large intestine? With brief descriptions
Cecum: Beginning of the colon, is fed chyme by the small intestine via ileocecal valve
Colon: Water and electrolytes are absorbed. Bacteria digest carbs and make vitamin B and K.
Rectum: Waste is collected, folds faeces awaiting elimination by defecation through the anal canal
