Coelom effectively subdivided into greater & lesser sacs by the stomach & 2 special mesenteries: greater & lesser omenta
Greater omentum-extensive folded membrane, extending from the greater curvature of the stomach to the back wall & dowm to the pelvic cavity; considerable fat ("pot belly" with excess) hangs down like a fatty apron over abdominal organs to protect & insulate.
Filled with plasma cells & other WBC. Can wraps around site of inflammation to wall off infectious organisms as with ruptured appendix, peptic ulcer, diverticulitis, etc
Superior esophageal sphincter-closed by passive elastic tension in the wall of the esophagus when esophageal muscles relaxed
Lower esophageal sphincter=cardiac sphincter Last 4 cm of esophagus. Relaxes only long enough to allow food & liquids to pass into stomach-remains contracted otherwise to prevent food & HCl from being forced back into esophagus with pressure in abdomen (breathing cycle, stomach contractions, late pregnancy)
If lower esophageal sphincter doesn't close heartburn
Covered by network of CT=Glisson's capsule. Located under diaphragm, mostly on R side. Held in place by peritoneal attachments & by intra-abdominal pressure created by tonus of abdominal wall musculature
Divided into 2 main lobes by falciform ligament, R lobe 6X larger, further subdivided into quadrate & caudate lobes
Bile ducts=bile canaliculi formed by bile capillaries that unite after collecting bile from liver cells drain into R & L hepatic ducts converge with cystic duct from the gallbladder to form the common bile duct
Common bile duct joins with main pancreatic duct enlarges into hepatopancreatic ampulla joins duodenal papilla which opens into the 2 nd part of the duodenum
Segmenting contractions-divide intestine into segments by sharp contractions of areas of circular smooth muscle in the intestinal wall. Duodenal segmentation caused by distension, ileal segmentation caused by gastrin
Peristaltic contractions-propulsive weak, repetitive waves which propel chyme through the sm intestine into colon. Regulated by motilin. Slow: ea wave takes 100-150 min from beginning to end of sm intestine
Monosaccharides like glucose & galactose taken up into intestinal epit cells by Na + cotransport (secondary active transport), fructose by passive transport.
Most amino acids taken up by active transport mech similar to that for glucose (different carriers for basic, acidic, & neutral amino acids-basic come in by passive transport). Di- & tripeptides split into constituent amino acids once inside the intestinal epit cells
9 l H 2 O enters gi tract/d. 92% absorbed in sm int, 6-7% absorbed in lg int. Water can move either way in sm int: when chyme is dilute H 2 O absorbed across intestinal wall into the blood; when chyme is conc H 2 O moves into the lumen of the sm int.
Osmotic P in sm int as nutrients absorbed & H 2 O moves from the intestine into the circulation