W19 Alimentary system Flashcards
what’s the difference between the phrases “tract” and “system” ?
Tract = tubular system (incl. Stomach and intestines) mouth - anus System = tracts, but also all glands and organs
Which layers does the tract anatomy consist of?
Innermost -> out
- Mucosa: villiated epithelium, CT, smooth muscle
- Submucosa: dense irregular CT
- Muscularis Externa (2 layers of smooth muscle)
- Serosa: Thin CT layer
Which three sections is the GI system divided into? Which are the constituent parts?
Foregut: Oesophagus, Stomach, Liver, Gallbladder, Dudodenum (proximal)
Midgut: Duodenum (distal), Jejunum, Ileum, Cecum, Appendix, Ascending colon, Transverse colon
Hindgut: Descending colon, sigmoid colon, Rectum
Oral cavity:
How does it digest food? Mechanically and chemically
Name the 3 glands found in the oral cavity.
Where they are situated?
Mechanically: mastication/physically breaking up food
Chemically: Salivary amylase turns STARCH into MALTOSE
Parotid gland: behind the jaw
Sublingual gland: under the tongue
Submandibular gland: behind the mandibles in the throat
Stomach:
How does it digest food?
What are some structural adaptations of the stomach?
Mechanically: churning/mixing food
Chemically: Pepsinogen (protein-smaller peptides)
HCl (kills bacteria)
Rennin (coagulates milk)
Rugae (wrinkles) accomodate stretch Gastric pits (hosts a variety of cells with a variety of functions)
Liver:
What does it secrete?
What is the function of this secretion?
What is the association with the gallbladder?
Liver produces and secretes bile
Bile helps break down lipids by breaking them down to small droplets
Bile is stored and concentrated in the gallbladder
Pancreas:
What is the function of the pancreas in terms of digestion?
Name the 3 enzymes present and their function
It produces most of the digestive enzymes in the small intestine
Proteolytic: protein breakdown
Nucleic acid enzyme
Pancreatic amylase: polysaccharide breakdown
Large intestine:
What is two structural feacture of the colon?
What is the main function of the colon?
Taena coli = smooth muscle tha bunches of the colon when it contracts
No villi, but crypts
Absorption of water and salts
Small intestine:
What are som structural adaptations?
What is the main function of the small intestine?
V. large SA due to:
The mucosa is highly folded
Mucosa is lined with villi
Cells lining villi have microvilli
Absorption of proteins, carbs, fat
What is the main function of the rectum?
Supports and stores faecal mass before defecation
How is the gut regulated?
The eneteric nervous system (part of ANS) and/or hormones
The previously mentioned regulatory system, the ___ ____ ___, recieves input from __ pathways. What are they?
Receptors
Hormones
Autonomic NS
What are the 3 phases of digestion? What happens during them?
Cephalic phase:
Salivaiton, para-NS responsible, INcreased bloodflow to glands
Gastric phase:
Stomach + duodenum relax to allow for chyme
Intestinal phase: Chyme moves through tract
Absorption occurs
Hormones:
Which one can be found in the stomach? Function?
Duodenum?
Gastrin: INcreases acid + pepsinogensecretion
Secretin: stimulates bile secretion (hinders acid secretion)
Cholecystokinin: stimulates bile + pancreatic secretion
Motilin: INcreases motility (clears tract between meals)
Hunger & Satiety:
What part of the body controls hunger & fullness?
Name of the The Hunger Hormone and the Satiety hormone?
How are they stimulated?
Two other hormones related to hunger/satiety?
Hypothalamus
Ghrelin: stimulated by empty stomach
Released by pancreas and stomach which tells the brain that you’re hungry
Leptin: Opposes Chrelin
Produced by adipocytes
Glucagon & Insulin:
G - secreted when blood glucose falls
I - secreted when blood sugar is high
From Islets of Langerhans
