GI system Flashcards
what is the GI system?
group of organs that work together to break down ingested food into smaller, absorbable nutrient molecules that can be absorbed into blood for distribution to all the cells in the body.
main function of the GI tract
digests or biochemically breaks down ingested food into small, simple nutrient molecules.
absorbs and transfers the nutrients, electrolytes and water from the ingested food into the systemic circulation
makes the preformed organic nutrient molecules in ingested food available to body cells as; source of fuel or energy, building blocks.
5 basic digestive processes of the Gi system
motility
secretion
digestion
absorption
storage and elimination of indigestible food.
motility
muscular contractions that mix and move forward the contents of the digestive tract.
two types of digestive motility:
propulsive movements: propel or push contents forward through the digestive tract
mixing movements: mix food with digestive juices and promote digestion. facilitate absorption of digested food.
secretion
several juices in Gi tract in response to specific neural or hormonal stimulation
consists of water, electrolytes, and specific organs constituents (enzymes, mucus etc)
includes both exocrine and endocrine secretions.
exocrine - H2O, HCL, HCO3, bile, lipase, pepsin.
endocrine - gastrin, secretin, CCK, VIP.
The gi system. digestion
the GI system asborption
Gi system diagram
2 main components o d the gi tract
alimentary canal
accessory organs and glands- pancreas, liver and salivary glands.
the upper part of the GI tract
mouth, esophagus and stomach
- serves as food intake source and receptacle
- site of intial digestive process
the middle part of the GI tract
small intestine - duodenum, jejunum and ileum
site of main digestive and absorptive processes.
the lower part of the GI tract
large intestine - caecum, colon and rectum
serves as the storage channel for efficient elimination of waste
wall structure of the alimentary canal
comprises 4 layers: mucosa, submucosa, muscularis externa, serosa.
mucosa
the innermost, moist, folded lining of epithelial cells, connective tissue, and smooth muscle cells.
main functions:
protective barrier against pathogens
secrets mucus, digestive enzymes, and hormones.
absorbs digested nutrients into the blood.
mucosa undergo rapid cell division and regeneration.
submucosa
dense connective tissue layer containing blood and lymphatic vessels, lymphoid follicles, and nerve fibres.
contains the submucosal nerve plexus of Meissner.
main functions:
- provides the digestive tract with distensibility and elasticity,
glands secrete digestive enzymes
nerve plexus helps regulate gut mobility.
muscular externa
serosa
complete extrinsic and intrinsic regulation of digestive function.
complex extrinsic and intrinsic regulation of digestive function diagram
digestive process diagram
digestive process from mouth to the stomach
stomach
acronym - efbapd
