What 4 things do we need food for?
- 1) Energy for cells
- 2) Storage of energy
- 3) Production of heat
- 4) Growth and repair
What are 3 essential nutrient?
- fats (lipids)
What are the three components of the digestive system?
- 1) Digestive process
- 2) Alimentary canal or GI tract
- 3) Accessory organs of digestion
What are the 5 digestive processes?
- 1) Ingestion
- 2) Propulsion
- 3) Digestion
- 4) Absorption
- 5) Elimination
What does ingestion do?
Takes food into alimentary canal (from mouth to anus)
What does propulsion do?
Mixing/ moving food along canal
What are the 2 types of digestion?
mechanical and chemical digestion
What does absorption do?
Digested substances from food enter blood/lymph vessels
What does elimination do?
Excretion of waste
The nerves are supplied to the GI tract by what system?
autonomic nervous system (involuntary)
What 4 things does the parasympathetic nervous system do to the digestive system?
- 1) Rest and digest
- 2) Increase peristalsis
- 3) Increases gland secretion (gastric juice + enzymes)
- 4) Increases saliva
What does the sympathetic nervous system do?
- 1) fight or flight
- 2) reduces peristalsis and secretion
What is the alimentary tract or GI tract?
Actively transports the flow of food through the whole of the digestive process.
Name 3 parts of the oral cavity that aid in digestion?
- Tongue- propels food bolus into oesophagus
- Teeth- Chewing breaks down food (mechanical digestion)
- Salivary glands- saliva contains enzymes which begin chemical digestion
Name the 3 parts of the Pharynx
What is the epiglottis?
- leaf shaped plate of yellow fibro elastic cartilage.
- located at entrance to larynx
- prevents food going down the larynx during swallowing
what is the oesophagus? (4 things)
- collapsible muscular tube
- descends from pharynx to cardiac sphincter in stomach
- 25cm long, 2 cm in diameter
- movement of food bolus along it by peristalsis
what is the oesophagus made up of?
- Smooth muscle
- elastic tissue
- mucous membrane
what is peristalsis?
- helps food move through the system
- by rhythmic, muscular contraction of the walls
- pushes food in one direction
What is the anatomy of the stomach?
- Muscular bag like organ
- walls lined with mucous membrane
- contains cardiac sphincter- connection with oesophagus which prevents regurgitation
What 2 types of digestion happen in the stomach?
- Mechanical digestion- stomach contracts to help churn up food.
- chemical digestion- mixes gastric juices, hydrochloric acid and enzymes to liquefy
What is liquefied food called?
What sphincter prevents regurgitation back into the stomach from the duodenum?
What is the duodenum?
- first part of small intestine
- bile and pancreatic duct empty into duodenum
- chemical digestion of carbs, protein and fats occur across the small intestine
- 25 cm long
Where does the chemical digestion of carbs, protein and fats take place?
Where do the bile and pancreatic ducts empty?
What is the small intestine?
Muscular tubes lined with connective tissue and mucous membrane
what is the small intestine comprised of?
Where does most water absorption happen?
where does the small intestine join the large intestine?
What is the outer covering if the small intestine called?
Why does the small intestine have a large surface area?
What passes through the inner lining of the small intestine and where is it absorbed?
- blood vessels in the wall of the intestine
what does the large intestine do?
- absorbs electrolytes and vitamins
- storage & expulsion of faeces
How long is the L intestine ?
What are the 5 main parts to the L intestine?
- Ascending colon
- transverse colon
- descending colon
- sigmoid colon
What is the peritoneum?
- serous membrane- lines abdominal cavity
- 2 layers which cover abdominal cavity
- prevents friction with serous fluid
- attaches organs to posterior abdominal wall
- carries blood vessels that help fight infection
What 3 organs also produce the chemicals necessary for digestion?
- salivary glands
What are 7 functions of the liver?
- carbs, fats and protein metabolism
- processing of drugs and hormones
- excretion of bilirubin
- produces bile
- storage of vitamins and minerals
- phagocytosis- RBC's, WBC's and some bacteria
- highest heat producing organ in the body
what does the gall bladder & bile do?
- helps digest fat to aid absorption
- stores and concentrates bile
- releases bile into the small intestine
Which part of the small intestine is bile released into?
How long is the pancreas? and where is it?
- 12-15 cm
- mainly lies behind stomach
What does exocrine mean in relation to pancreas?
secretes enzymes (pancreatic) directly into duodenum- digest carbs, fats and proteins
What does endocrine mean in relation to pancreas?
Secretes hormones (insulin and glucagon) directly into the blood to control blood glucose levels.