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What 4 things do we need food for?
- 1) Energy for cells
- 2) Storage of energy
- 3) Production of heat
- 4) Growth and repair
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What are 3 essential nutrient?
- Protein
- carbs
- fats (lipids)
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What are the three components of the digestive system?
- 1) Digestive process
- 2) Alimentary canal or GI tract
- 3) Accessory organs of digestion
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What are the 5 digestive processes?
- 1) Ingestion
- 2) Propulsion
- 3) Digestion
- 4) Absorption
- 5) Elimination
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What does ingestion do?
Takes food into alimentary canal (from mouth to anus)
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What does propulsion do?
Mixing/ moving food along canal
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What are the 2 types of digestion?
mechanical and chemical digestion
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What does absorption do?
Digested substances from food enter blood/lymph vessels
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What does elimination do?
Excretion of waste
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The nerves are supplied to the GI tract by what system?
autonomic nervous system (involuntary)
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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
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What does the sympathetic nervous system do?
- 1) fight or flight
- 2) reduces peristalsis and secretion
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What is the alimentary tract or GI tract?
Actively transports the flow of food through the whole of the digestive process.
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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
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Name the 3 parts of the Pharynx
- Nasopharynx
- oropharynx
- laryngopharynx
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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
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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
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what is the oesophagus made up of?
- Smooth muscle
- elastic tissue
- mucous membrane
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what is peristalsis?
- helps food move through the system
- by rhythmic, muscular contraction of the walls
- pushes food in one direction
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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
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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
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What is liquefied food called?
Chyme
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What sphincter prevents regurgitation back into the stomach from the duodenum?
Pyloric sphincter
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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
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Where does the chemical digestion of carbs, protein and fats take place?
Duodenum
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Where do the bile and pancreatic ducts empty?
Duodenum
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What is the small intestine?
Muscular tubes lined with connective tissue and mucous membrane
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what is the small intestine comprised of?
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Where does most water absorption happen?
Small intestine
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where does the small intestine join the large intestine?
Ileum
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What is the outer covering if the small intestine called?
Peritoneum
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Why does the small intestine have a large surface area?
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What passes through the inner lining of the small intestine and where is it absorbed?
- nutrients
- blood vessels in the wall of the intestine
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what does the large intestine do?
- absorbs electrolytes and vitamins
- storage & expulsion of faeces
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How long is the L intestine ?
1.5 m
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What are the 5 main parts to the L intestine?
- Ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
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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
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What 3 organs also produce the chemicals necessary for digestion?
- salivary glands
- liver
- pancreas
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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
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what does the gall bladder & bile do?
- helps digest fat to aid absorption
- stores and concentrates bile
- releases bile into the small intestine
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Which part of the small intestine is bile released into?
duodenum
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How long is the pancreas? and where is it?
- 12-15 cm
- mainly lies behind stomach
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What does exocrine mean in relation to pancreas?
secretes enzymes (pancreatic) directly into duodenum- digest carbs, fats and proteins
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What does endocrine mean in relation to pancreas?
Secretes hormones (insulin and glucagon) directly into the blood to control blood glucose levels.
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