Lesson 82 - Small Intestine Part 2

What is different about the horses small intestine?

ascending duodenum is very short and ileum opens into the cecum

Where is the small intestine in horses?

more left dorsal in the abdominal cavity

What gives the horses small intestine its large degree of mobility?

long mesentery

What structures are seen in the ileum, cecum, colon of horses?

ileal papilla, ileocecal fold, caecocolic orifice

What is unique about the large intestine in ruminants?

spiral colon

What does the ileum open into in ruminants?

cecum

Where is the jejunum in ruminants?

ventral

Where is the jejunum in pigs?

on the right side when stomach is fully distended

What does the ileum open into in pigs?

cecum

What are the parts of the pancreas?

body and two lobes

What is the right lobe of the pancreas associated with?

duodenum

What is the left lobe of the pancreas associated with?

stomach greater curvature

What is the primary function of the exocrine pancreas?

digestion

What does the pancreas secrete?

amylase, lipase, proteases

What are some proteases that the pancreas secretes?

trypsinogen, chymotripsinogen, carboxypeptidase

What hormones regulate the pancreas secreting enzymes?

cholecystokinin and secretin

What is the right lobe of the pancreas enclosed in?

mesoduodenum

What is the left lobe of the pancreas enclosed in?

deep leaf of the greater omentum

What is the right lobe of the liver ventral to?

right kidney

What arteries supply the pancreas?

cranial and caudal pancreaticoduodenal artery

Where does the cranial pancreaticoduodenal artery come from?

gastroduodenal artery

Where does the caudal pancreaticoduodenal artery come from?

cranial mesenteric artery

Where is the pancreas in ruminants?

more to the right

What is unique about the pancreas in horses?

hepatic portal vein perforates the pancreas

What are the pancreatic ducts of the cat like?

large pancreatic duct with small accessory pancreatic in only 20% of cats

What are the pancreatic ducts of the dog like?

small pancreatic duct and large accessory pancreatic duct

What are the pancreatic ducts of the cow like?

rarely have pancreatic ducts but have accessory pancreatic duct

What are the pancreatic ducts of the horse like?

large pancreatic duct with small accessory pancreatic duct

What are the pancreatic ducts of the pig like?

no pancreatic duct and only accessory pancreatic duct

What are the anatomic adaptations of the small intestine mucosa for absorption?

plicae circulares, villi, microvilli

What is the function of the mucosa in small intestine?

absorption

What are the villi lined by?

columnar epithelial cells called enterocytes

What do enterocytes have on their apical membrane?

goblet cells

What is the function of enterocytes?

digestion and absorption

What cells are interspersed with the enterocytes?

goblet cells

What is the function of goblet cells?

produce mucus

Which part of the small intestine have more goblet cells?

distal segment

What forms the villi?

lamina propria and mucosa

What does the core of the villi contain?

loose connective tissue, vessels, lymphocytes, plasma cells

What are the villi like in carnivores?

long and thin

What are the villi like in ruminants?

short and thick

What are the base of the villi called?

crypts of leibekuhn

What are present in the crypts of leibekuhn?

epithelial stem cells

What do the epithelial stem cells in the crypts differentiate into?

enterocytes, accessory cells, or goblet cells

What are some accessory cells?

paneth cells and enteroendocrine cells

What are paneth cells?

cells with eosinophilic granules of antimicrobial molecules for gut innate immunity

What species have paneth cells?

horses

What are enteroendocrine cells?

cells the produce hormones like somatostatin, cholecystokinin, secretin

What glands are in the duodenal submucosa?

tubuloacinar glands called Brunner's glands

What are Brunner's glands?

tall columnar cells that produce alkaline mucin

What tissue is highly present in the ileum?

lymphoid tissue called Peyer's patches

What type of lymphoid organ is peyer's patches?

primary and secondary

What layers does the tunica muscularis of the small intestine have?

inner circular and outer longitudinal

What species has the thickest tunica muscularis?

horses

What covers the pancreas?

capsule

What divides the pancreas into lobules?

stroma

What are the secretory units for the pancreas?

tubuloacinar

What animal has a more prominent tubular portion in small intestine?

ruminants

What do the cytoplasm of tubuloacinar cells contain?

lots of RER, mitochondria, golgi complex

What do acinar cells have receptors for?

cholecystokinin

How does cholecystokinin influence acinar cells?

stimulates the release of pancreatic enzymes as well as contraction of the gall bladder

What duct leaves the tubuloacinar secretory unit?

intercalated duct

What does the intercalated duct start with?

centroacinar cells

What do centroacinar cells and intercalated duct cells secrete?

bicarbonate and water

What stimulates centroacinar and intercalated duct cells to secrete?

secretin

What ducts do the intercalated ducts join?

intralobular ducts

What ducts do the intralobular ducts join?

interlobular ducts

What lines the intralobular ducts?

simple cuboidal

What lines the interlobular ducts?

simple columnar

What do the interlobular ducts form?

pancreatic ducts

What ducts can have goblet cells?

larger ducts