Digestive System Flashcards
Function of liver and gall bladder
Liver - produces bile
Gall bladder - stores vile and releases it into the S.I
Structure of Digestive system (18 Things)
oral cavity, salivary glands, pharynx, liver, oesophagus, liver, gall bladder, stomach, pyloric sphincter, duodendum, pancreas, transverse colon, ascending colon. descending colon, caecum, appendix, small intestine, rectum, anus
Function of Mouth, salivary glands, pharynx, oesophagus,
Mouth: chemical digestion of starch by saliva. Mechanical digestion of food by teeth (Mastication)
Salivary glands: produce saliva
Pharynx: moves up and back, ready for swallowing
Esophagus: carries food from the mouth to the stomach
Function of Colons
absorbs, water, minerals, vitamins
function of stomach, pyloric sphincter, duodendum and pancreas
Stomach: M.D - churning action. C.D pepsin.
Pyloric sphincter - regulates flow of material from stomach to duodendum
Duodendum: first part of small intestine
Pancreas: produces pancreatic juices containing enzymes fro digesting proteins, lipids and nucleic acids
Function of small intestine
secretes intestinal juice. Lined with villi for absorption of digested food
function of caecum, appendix, rectum and anus
Caecum - first part of large intestine
Appendix - stores useful bacteria, plays a role in immunity
Rectum - final part of large intestine in which faeces are formed
Anus - opening surrounded by the anal sphincter muscle that can be voluntarily controlled
mechanical digestion
the mechanical breakdown of food into small particles.
Examples: Chewing of food with teeth(mastication). Churning of food in the stomach. peristalsis - oesophagus, S.I and L.I
chemical digestion
the breakdown of food to small molecules by chemicals
Examples: Breakdown of starch in mouth by salivary amylase. Breakdown of food in stomach by pepsin.
Teeth
4 incisors
2 canines
4 premolars
6 molars
mucosa
internal lining of the stomach
specialised for secretion of gastric juices
Chyme
made up of HCL, mucus and pepsin.
Pepsin - enzyme that works in very acidic solutions
HCl - allows protease to work and kills bacteria that enters stomach
Mucus - protects stomach from acidic chyme & bacteria
Prevents nutrient transfer at this stage of the alimentary canal
absorption
nutrients are absorbed through the internal wall of the small intestine into the blood
Occurs in S.I
absorbs: monosaccharides, amino acids, fatty acids, glycerol, vitamins, minerals and water
Absorption occurs via:
- Simple diffusion
- active transport
A.A, simple sugars, fatty acids & glycerol, water and water-soluble vitamins
Small intestine - order
Duodendum - mixing bowl; acid neutralization. secretes alkaline mucus which neutralises HCl, lubricates s.i, creates a suitable pH level for chemical digestion and protects the wall of the duodenum
Jejunum - bulk of chemical digestion and nutrient absorption occurs here
Ileum - vitamin b12 absorption
Intestinal juice
Clear to pale yellow, watery secretion released from the glands and mucous-membrane lining of the small and large intestines
enzyme table
salivary amylase - mouth - starch - maltose
Pepsin - stomach - protein - polypeptides
Bile salts - liver, s.i - fat - fat droplets
Amylase, protease, lipase - s.i - starch, protein and fat - a.a, glycerol, maltose
Emulsification
Bile produced by the liver but stored in the gall bladder.
- bile salts emulsify fat breaking it into small droplets
- contains no digestive enzymes
Villi
made up of epithelium - one cell thick outer layer
blood capillary - surrounding the lacteal - absorbs a.a and glucose
lacteal - absorbs fatty acids and glycerol
whether absorption is simple or active transpo
A.A - active - blood capillaries
Simple sugars - active - blood capillaries
Fatty acids and glycerol - simple diffusion - lacteal
Water - simple diffusion - blood capillaries
Water soluble vitamins - simple - blood capillaries
Nutrients
Carbs - polysaccharide - disaccharide - monosaccharide/simple sugars
protein - polysaccharide - disaccharide - a.a
Lipids - small fat droplets - fatty acids & glycerol
Digestive enzymes
Protease - breakdown proteins into a.a
Lipase - breakdown fats into fatty acids & glycerol
Amylase - breakdown carbs into simple sugars
amylase
salivary - breakdown starch
Pancreatic - continues to breakdown polysaccharides
Intestinal amylase - breaks down maltose
Protease
gastric - breaks down proteins
Pancreatic - breaks down polypeptides
intestinal - break down dipeptides
Lipid
Pancreatic - tiny lipid droplets
Intestinal - tiny lipid droplets
structure of l.i
caecum - site where s.i and l.i meet
ascending colon - RHS of colon moving up
Transverse colon - moving horizontally
Descending colon - LHS of colon moving down
Oesophagus*
the tube that carries food from the throat to the stomach
Pyloric sphincter*
a ring smooth muscle between the stomach and duodenum
Elimination
removal of undigested food
Stomach*
Pepsin degrades proteins to polypeptides
Protein
s.i: trypsin degrades polypeptides to peptides
Peptides: degrade peptide to amino acids
