4. Fuel for life Flashcards
Digestion
= the mechanical and chemical breakdown of food to absorb nutrients and functioning
- essential for energy, growth and maintenance of our bodies
- glucose is an essential source of energy release from varied food sources by enzymes and hormone insulin
- in healthy body water, monosaccharides, aa, fatty acids and glycerol, vitamins and minerals absorbed within an appropriate range
Digestive system anatomy in order
- Oral cavity
- salivary glands
- saliva
- oesophagus/ esophagus
- stomach
- small intestine
- Accessory organ secretion - liver and pancreas
- large intestine
Oral cavity
= lips cheeks, teeth and tounge
mechanical - biting and chewing mechanics chops food into small pieces to swallow
Salivary glands
= 3 pairs - parotid, submandibular and sublingutar glands
- produce saliva through ducts into mouth
- Salivary amylase enzymes converts polysaccharides to disaccharides
Saliva
= mixture of serous and mucus fluids
serous (watery) component
- moistens food for swallowing
- dissolves food for tasting
- contains enzymes amylase - carbohydrates for state of
chemical digestion
mucous component
- lubricates food
- enzyme lysosym is antibacterial
Oesophagus
= muscular contractions in oesophagus occur in peristaltic waves to push food down tract
Stomach
= huge muscular sac that is a J shaped enlargement of GI tract (4 functions) - food churned (mechanical breakdown)
- Mixes saliva, food, gastric juice to form chyme (chemical breakdown)
- Serves as a resviour for food before release into small intestine
- Secretes gastric juice, which contains
- HCL - kills bacteria dn denatures proteins
- pepsin - begins the digestion of proteins
- intrinsic factor - aids absorption of vitamin B12
- gastric lipase - aids digestion of triglycerides - secretes gastrin into blood
Small intestine
= digestion and absorption
- three parts - Duodenum, jejunum and ileum
Modification increase surface area
- circular folds: mucosa and submucosa
- Cilli: finger like projection from mucosa
- microvilli
- food entering the small intestine is only particularly digested
- secrets digestive enzymes
Accessory organ secretion
Liver = produces bile to aid digestion
- stored in galbladder
- bile allows secretion
Pancreas
- bicarbonate to neutralise acidic chyme
- enzymes
Large intestine
4 main functions
- reabsorption of water and mineral ions
- formation and temporary storage of faeces
- maintain residence pop of over 500 species of bacteria
- assist vitamin production
- defecation (empty rectum)
Colon = mucosal lining with tubular glands which contains mucous producing goblet cells
Rectum = straight muscular tube
Anal canal = waste on the way out
Anatomy of the GI tract
4 layers of tissue called tunics:
- Tunica Serosa - protection/ covering
- Tunic muscularis - longitudinal and circular which work together to propel food/ chyme through digestive tract
- Tunic submucosa - loose tissue containing blood and lymphatic vessels, provide nervous control to mucosa
- Tunica mucosa - inner layer - secretion, absorption and hormone
What does the stomach absorb
=water , alcohol, aspirin
Pancreas
- gland that lies in the posterior of the stomach
- produces enzymes that digest carbohydrates, proteins, fats, nucleic acids
- produces bicarbonate
- empties contents into duodenum
Endocrine and exocrine function in pancreas?
Endocrine = organs release hormones
- insulin and glucagon
Exocrine = relate to releasing a substance through a duct
- release enzymes that aid digestion
- pancreatic lipase
- amylase
Pancreatic juice
= helps to protect and prevent erosion of the intestinal mucosa
- digestive enzymes which breakdown
