23 19-24 Flashcards
Pancreatic juice pH?
7.5-8.8
Large intestine gross anatomy structure? 9
Ileocecal valve, cecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal
Cecum
Lies below the ileocecal valve, first part of large intestine
Appendix
Attached to posteromedial surface of cecum.
Contains masses of lymph tissue/MALT.
Storehouse for bacteria - recolonizes gut.
Twisted shape can provide a place for unwanted bacteria breeding.
Anus has both?
An internal/involuntary and external/voluntary sphincter.
Large intestine function?
Move poop.
Absorb remaining water, bile salts, bacterial generated vitamin K, biotin (glucose metabolism), and vitamin B5 (used to manufacture steroids and some neurotransmitters)
Specialized structures of the large intestine?
Teniae coli, Epiploic appendages, haustra
Teniae coli
3 bands of smooth muscle (reduced muscularis compared to other sections)
Epiploic appendages
Fat filled pouches of visceral peritoneum hanging from the surface of the large intestine.
Haustra
Puckers in the large intestine caused by the teniae coli
Micro anatomy of the large intestine?
Simple columnar epithelium.
No folds/villi/digestive juice secreting cells.
Mucosa is thicker, crypts are deeper and contain lots of goblet cells to keep things moving.
Micro anatomy of the anal canal?
Anal canal is stratified squamous.
Anal sinuses exude mucus.
Superficial venous plexuses can = hemorrhoids.
Complete muscularis layers.
No tenaie coli/haustra
How long are substances in the large intestine?
12-24 hours
Motility of large intestine?
Haustral contractions: Occur mostly in the ascending/transverse. Sluggish/short-lived, last about one minute every 30 minutes.
Mass movements: (mass peristalsis) Long/slow-moving, 3-4 times daily. Food in stomach causes gastrocolic reflex.
Peristalsis
Enzymes for digestion of proteins?
Stomach: Pepsin
From pancreas: Trypsin, chymotrypsin, carboxypepsidase
Brush border: Aminopesidase, carboxypepsidase, dipepsidase
Enzymes for digestion of carbs?
Mouth: salivary amylase
Pancreas: Pancreatic amylase
Brush border: Dextrinase, glucoamylase, lactase, maltase, sucrase
Enzymes for digestion of lipids?
Mouth: lingual lipase
Stomach: gastric lipase
Liver: bile
Pancreas: pancreatic lipases
Process of absorption of amino acids?
- The amino acids are absorbed by active transport into their absorptive cell and move to the opposite side.
- Amino acids leave the villus epithelial cell by facilitated diffusion on a carrier and enter the capillary via intercellular clefts.
Process of absorption of carbs?
Glucose and galactose are shuttled by secondary active transport with Na+ into the epithelial cells.
They then move out by facilitated diffusion and pass into the capillaries via intercellular clefts.
Fructose moves entirely by facilitated diffusion.
Process of absorption of lipids?
- Free fatty acids and monoglycerides associate with bile salts to form micelles which ferry them to the intestinal mucosa.
- Fatty acids/monoglycerides leave micelles and diffuse into epithelial cells. They are recombined and packaged with other fatty substances and proteins to form chylomicrons.
- Chylomicrons are extruded from the epithelial cells by exocytosis. Chylomicrons enter lacteals and are carried away in lymph.
(short chain fatty acids can simply diffuse into the portal blood for distribution)
Structural and functional properties of smooth muscle?
- Long, slow contractions
- Basal tone (always a low level of contraction)
- Sphincters (act as valves, ctrl movement)
- Basic electrical rhythm (gap junctions to coordinate movement)
Enchilada - MOUTH
MOTILITY
chewing/mechanical
SECRETORY
saliva/1500ml
DIGESTION
Amylase, lingual lipase
Enchilada - STOMACH
MOTILITY
Peristalsis/churning/mixing/emptying
SECRETORY
Gastric juice/2000ml (mucus-HCl-enzymes-paracrines)
DIGESTION Pepsin (1st start on protein), salivary amylase still active for maybe an hour, lingual/gastric lipase
ABSORPTION
Alcohol/aspirin
Enchilada - SM INTESTINE
MOTILITY
Peristalsis/segmentation/migrating motility complex
SECRETORY
Intestinal juice 1500/pancreatic juice 1500/bile 500
DIGESTION
protein–>aa, lipids–>ffa, carb–>glucose
ABSORPTION
nutrients
