Digestive System Flashcards
What is the mesentery?
The fold of the peritoneum that attaches the digestive system to the abdominal wall.
Going from the lumen of the gut moving onwards, name the layers.
Lumen Epithelium Lamina Propia Muscularis Mucosae Muscularis Externa Submucosa Serosa
Name some functions of the digestive system.
Store food Digest food Kill pathogens Remove waste material Move food along
What does saliva contain?
Lipase and amylase to start digestion, bacteriastatic (antibodies), alkaline, calcium to protect teeth
What does the saliva turn into?
A bolus
What does the stomach turn the bolus into?
Hypertonic Chyme
What is the name of the folds in the stomach?
Rugae
‘Fold’ or ‘wrinke’ in Latin
What do surface mucous cells in the stomach secrete?
HCO-3 ions which neutralise H+ ions and protect lining of stomach.
Where does the chyme go after the stomach?
The duodenum
What are the five layers on cells in a gastric gland and what do they do?
Gastric pit - mucus secreting cells
Isthmus - where stem cells divide
Parietal cells - secrete HC03-
Chief cells - secrete pepsinogens which hydrolyse proteins
Enteroendocrine cells - secrete gastric and causes wider gastric mucosa to secret acid.
What glands does the duodenum contain and what do they secrete?
Brunner’s glands - secrete bicarbonate rich mucus to neutralise chyme.
What other substances are realised into the duodenum and where from?
H20 from the extracellular fluid
Bile from the liver
Enzyme from the pancreas and liver
What do the enzymes from the pancreas and liver break down?
Peptides into amino acids
Polysaccharides into monosaccharides
Lipids
What are the folds in the jejunum called?
Plicae circularis
Name the layers of the jejunum.
In centre of folds: Muscularis Mucosal
Jejunal mucosa
Submucosa and muscularis externa underneath
Villi on the folds
What is a lacteal?
A lympathetic vessel of the small intestine, absorbs fats.
What do the a) Duodenum b)Jejunum and c) Illeum absorb?
A) ions
B) Sugars, amino acids, fatty acid
C) all nutrients absorbed, still contains water
Name the different parts of the colon.
Appendix, Caecum, Ascending colon, Transverse colon, Descending colon, Sigmoid colon, Rectum.
What are crypts of lieberkuhn?
Intestinal glands that line epithelium and mucosa.
What do we not excrete involuntarily?
Our higher control centre overrides any reflex, can reverse peristalsis (involuntary movement of GI tract).
What three processes in the bacteria in the colon used in?
Synthesis of vitamins K, B12, thiamine
Breakdown of bile acids
Conversion of bilirubin to non-pigmented metabolites
What two things can decreased fluid absorption result in?
Dehydration and electrolyte imbalance
Name two neuronal plexus in the gut where they are found.
Submucosal plexus (plexus of Meisser) - found between the layers of the gut Myenteric plexus - between submucosa and muscularis externa.
How does paracrine control control our fluid retention?
Histamine - controls acid in stomach
Vasoactive substance - control blood flow in the gut
What does the hormone secretin do?
Promotes HCO-3 secretion from pancreas
Promotes bile production
Inhibits acid secretion in stomach
Where the hormone gastric releases and what does it do?
Released by G cells in stomach, pancreas, duodenum
Promotes gastric acid in the stomach.
What does the hormone cholecystokinin (CCK) do?
Synthesised by enteroendocrine cells of duodenum
Promotes digestive enzymes in pancreas
Promotes bile in the gall bladder
is a hunger suppressant
