test 5 Flashcards
Mesentery
– dorsal and ventral • Double layer of peritoneum • Hold everything in place - Organs - Nerves - Blood vessels
Retroperitoneal Organs
Not covered by peritoneum but behind the peritoneal cavity: • Pancreas • Duodenum • Ascending and descending colon • Rectum *lose their mesenteries
Ventral Mesentery
Falciform ligament
• Anterior of liver to the anterior abdominal wall and
diaphragm
• Lesser omentum
• Liver to the superior part of the stomach
Dorsal Mesentery
Greater omentum:
• Connects the stomach to the posterior abdominal wall
Transverse mesocolon:
• Connects the transverse colon to the posterior wall
Sigmoid mesocolon:
• Connects the sigmoid colon to the posterior pelvic wall
Anatomy of alimentary canal
• Mucosa:
-innermost layer, functions in absorption and secretion. composed of epithelium cells and a thin connective tissue. contains specialized goblet cells that secrete sticky mucus throughout the GI tract.
• Submucosa:
-supports the mucosa, as well as joins the mucosa to the bulk of underlying smooth muscle. contains major blood and lymphatic vessels and nerve fibres and glands
• Muscularis Externa:
-segmental contractions and peristaltic movement in the GI tract. These muscles cause food to move and churn together with digestive enzymes down the GI tract. The muscularis externa consists of an inner circular layer and a longitudinal outer muscular layer.
• Serosa:
-visceral peritoneum, outermost layer of most intraperitoneal organs
smooth muscle fibres
- no striations
- elongated shape
- dense bodies connected by network of intermediate filaments
- gap junctions connect adjacent fibres and help to spread transmission
innervation: ANS fibres covered in varicosities, the synaptic cleft is wider so longer diffusion time, muscles don’t fatigue
Enteric Nervous System
• “Brain” within the alimentary canal • Can function independently Myenteric nerve plexus • in Muscularis externa, involved in peristalsis Submuscosal nerve plexus • in Submuscosa, innervates glands
teeth
deciduous teeth start to appear approx. 6 months-2yrs-
-start to lose them by approx. 7 yrs and are replaced by permanent teeth
salivary glands
3 glands:
- sublingual
- submandibular
- Parotid
saliva functions
- secretion of enzymes for fat and carbohydrate breakdown
- immune function
- lubrication of the mouth
- creation of food bolus
Esophagus
Adventita: the outermost layer, like mesentery but not a serosa because not in the peritoneal cavity
- stratified squamous epithelium because friction caused from swallowing can rub cells off over time
- in a relaxed state it is folded, but expands after swallowing
what are the Stomach muscles and what do rugae do?
3 muscle layers: longitudinal, circular and oblique
-rugae allow the stomach to fold up when empty and expand when full
Cell types in the stomach
Mucous cells: only cell type in gastric pit
• Secrete bicarbonate mucous on epithelial surface (prevents digestion of stomach wall)
Mucous neck cells:
• Occur in the neck of the gastric gland
• Secrete mucous of unknown function
Parietal cells:
• Produce HCl
Chief cells:
• Secrete pepsinogen – inactive enzyme (activated to pepsin by HCl)
Enteroendocrine cells:
• produce and secrete hormones into the blood vessels of lamina propria
Small Intestine- function and subdivisions
• Longest segment of the alimentary canal • Most of the digestion • Most of the absorption • Uses peristalsis to move chyme along the canal 3 subdivisions: • Duodenum • Jejunum • ileum
Duodenum
Receives digestive enzymes and chemicals from the
accessory digestive organs
• Pancreas
• Gallbladder
• Liver
• All enter through the hepatopancreatic ampulla which
opens into the duodenum through the major duodenal
papilla
Pancreas
• Store and secrete digestive enzymes in acinar cells
• Duct cells secrete sodium bicarbonate that enters the digestive tract
Acinar cells:
-A lot of RER for enzyme production (packaging into vesicles)
-Stored as zymogen granules
-stimulate release through exocytosis
Gallbladder
• Stores and concentrates bile from the liver
• Cystic duct of the gallbladder joins the common
hepatic duct of the liver to form the bile duct
• Bile is important for digestion of fats
Absorption in Small Intestine
Very large surface area
• Long length
• Circular folds: force chyme to spiral
• Villi: contain blood and lymphatic vessels, absorptive
cells
• Microvilli: on the surface of epithelial cells, contains
enzymes to complete final digestion
Lacteals
• Absorb digested fats
• Go into general circulation before reaching the liver
unlike other digested material (too large to enter blood capillaries)
• Bypasses “first pass metabolism”
Small Intestine Cells
Absorptive Enterocytes • Absorb digested material Goblet cells • Secrete lubricating mucus Enteroendocrine cells • Secrete hormones for bile and enzyme release
Large Intestine Cells
-dimples/haustrums = bunching of the muscle layer, formed by teniae coli
-epiploic appendages= full of fat, unknown function
Colonocytes
• Absorptive cells – absorb water and electrolytes
Goblet cells
• Abundant – secrete mucus
Liver
- bare area- no mesentery, partially fused to diaphragm
- hepatic arteries supply nutrients to the liver
- portal vein brings the blood to the liver, hepatic vein brings blood from the liver to general circulation
Liver Lobules
- central vein brings material for filtration
- surrounded by connective tissue septum
Urinary System functions
• Maintain purity and chemical consistency of the body: • Gets rid of waste • Ensures proper osmolarity and pH • Ensures proper blood volume • Filters toxins
