Digestive System Flashcards
Digestion
The physical and chemical breaking down of food into its constituents molecules, which can be absorbed into the bloodstream
Ingestion
The process of taking in food (mouth)
Absorption
The passage of single biomolecules from the gut into the bloodstream
Assimilation
The movement of digested food molecules into the cells of the body where they are used
Ejestion
The getting rid of undigested material from the body.
Stages of Digestion
Ingestion Digestion Absorption Assimilation Ejestion
Physical/Mechanical Digestion
Teeth Muscle, e.g. muscle of the stomach chewing Churning Peristalsis
Buccal Cavity
Teeth or chewing (Mechanical Digestion)
Salivary Glands
Produces saliva to digest bolus of food (Chemical Digestion)
Oesophagus
Food to Stomach by peristalsis
a wave of muscular contractions
Stomach
Muscular bag lined with gastric glands
Secretes gastric juices
Churns and mixes food with gastric juices
Adaptions of stomach
Mucous - goblet cells - prevent self-digestion
Pepsinogen - zymogen cells - Inactive enzymes
Hydrochloric acid - oxyntic cells - Kills bacteria
Small Intestine
Duodenum, jejunum and ileum
Lined with villi
Each villus has 600 microvilli
Produces Vitamin B and K
Receives pancreatic juices from pancreas and bile from gall bladder
Absorption (glucose, amino acids, fatty acids)
Large Intestine
Holds food
Caecum and appendix - vestigial organs
Colon reabsorbs water
Faeces stored in rectum
Symbiotic Bacteria
Colon bacteria feed on wate in large intestine and produces Vitamin B and K
Pancreas
Exocrine gland produces pancreatic juices (duct)
Endocrine gland produces insulin (ductless)
Pancreatic amylase and pancreatic lipase
Sodium hydrogen carbonate neutralises chyme
Liver
- Makes bile (Emulsifies fats and excrete pigments)
- Detoxifies body
- Deamination (Removing amino part to excess nitrogen)
- Makes fibrinogen
Villus
One cell thick
Good network of blood capillaries
LSA due to large number of microvilli
Peristalsis
Rhythmic muscular contraction and relaxation in the wall of the alimentary canal causing the food to move along the canal
Canines
Tearing
Incisors
Cutting
Molars and Pre-molars
Crushing and Grinding
Humans Dental Formula
I 2/2, C 1/1, PM 2/2, M 3/3
Baby Teeth
20 teeth
Adult Teeth
32 teeth
Amylase
Made in salivary glands
Active in mouth
pH 7
Starch to maltose
Protease
Made in salivary glands (gastric juices)
Active in stomach
pH 2
Proteins to polypepetides
Pepsin
Made in gastric glands
Active in stomach
pH 1/2
Protein to peptides
Lipase
Made in pancreas
Active in duodenum
pH 8
Lipids to glycerol and fatty acids
Balanced Diet
A diet that consists of all 7 nutrients in the right amount to meet the needs of the body
Advantages of Dietary Fibre
Stimulates peristalsis in the colon
Helps prevent constipation
Cause of constipation
When undigested materials pass through too slowly
Too much water is being reabsorbed
Mouth
Physical digestion
Chemical Digestion
Starch using amylase to maltose
Adaptations of Small Intestine
Made of muscle Duodenum produces enzymes Long Has villi Thin walls
