Anatomy Flashcards
Peritoneum
serous membrane
simple squamous epithelium with underlying connective tissue
secretes luid to make surface moist and slippery.
Peritoneum structures
visceral peritoneum - lines organs
Parietal peritoneum - lines wall of abdomen
Mesentery - double layer peritoneal membrane from body wall to organ, passage to blood vessels, nerves and lymphatics
Omentum - double layer peritoneal, organ to organ
retroperitoneal - behind peritoneum
Functions of Peritoneum
Form covering of abdominal organs Create smooth surface mesentery and omentum serve as fat stores hold organs in position fats prevent infections
Arterial Supply of abdominal viscera
Blood supply is a result of embryological structure
Celiac trunk supplies foregut (common hepatic, left gastric, splenic)
Superior mesenteric artery supplies midgut (Intestinal arteries, Ileocolic artery, colic arteries)
Inferior mesenteric artery supplies hindgut (Left coin artery, Sigmoid artery, Superior rectal artery)
Layers of GI tract
Mucosa
Epithelium (no BV, nerves, lymphatics), (secretion)
Lamina Propria (LFCT, BV, nerves, lymphatics)
Muscular muscosa (smooth muscle)
Submucosa (connective tissue, BV, lymph, submucosal plexus)
Muscular externa ( Smooth muscle, inner circular, outer longitudinal, myenteric plexus)
Adventitia (Outermost, FCT)
Epithelium of GI tract
Simple Squamous = Peritoneum
Stratified Squamous = oesophagus, anal canal
Simple Cuboidal = lining ducts
Simple columnar = SI
Glandular epithelium
Certain regions of GI tract have exocrine glands
Unicellular glands e.g. goblet cells
Multicellular glands e.g.columnar cells
Simple glands: simple duct
Compound glands: multiple ducts
Mouth
food ingested, masticated then delegation (swallowed)
food forced through fauces to oropharynx into oesophagus.
stratified squamous for protection
Functions of Saliva
Moistens ingested material
Moistens, cleans and lubricates oral cavity
chemically digests carbs with amylase
contains lysozyme (Antibacterial)
3 paired salivary glands
Parotid - (secretes serous fluid, contributes 25%-30% total saliva, largest)
Submandibular - (secrets mucous+serous fluid, 60-70% of total saliva, ducts open in floors of mouth)
Sublingual Glands - (secretes mainly mucus, 3-5% of total saliva, ducts open into inferior surface)
Oesophagus
transports food from oral cavity to stomach
mucosa - (epithelium=stratified squamous, Lamina Propria=mucus secreting glands)
Muscularis - (transitions between skeletal muscle superior to smooth muscle inferior)
Stomach
Functions - (storage of food, mechanical and chemical digestion)
Regions - cardia, fundus, body, pylorus
oesophagus opens into cardia via lower oesophageal sphincter
Pylorus opens into duodenum via pyloric sphincter
Columnar epithelium containing mucus cells
Submucosa - (rugae - non uniformal folds which allow distension)
Muscularis - (3rd layer of smooth muscle, helps with specific motility patterns of stomach)
Gastric Pits and Glands
- Invaginations in the stomach
- different epithelium
- mucous neck cells
- Chief cells (secrete enzymes for chemical digestion, therefore lots of rough ER)
- Parietal cells (secrete acid)
- Endocrine cells (secrete hormones)
- Stem cells (differentiate into different types of epithelial cells)
Small Intestine
- Pyloric sphincter controls release of acidic chyme into the duodenum (first section of small Intestine)
- Jejunum (second section)
- Ileum (Final Section, Terminates at ileoceceal junction where chyme passes to cecum)
Histology of Small Intestine
Structural Adaptations maximise absorptive surface area
- PIlicae Circularis (Core of submucosa and Overlying mucosa)
- Villus (Core of FCT, contains lymph, Capillary Network - rich blood supply to absorb products of digestion, covered with epithelial columnar cells)
- Microvilli - cover apical surface of the columnar cells on each microvillus (covered by glycocalyx - fine branched filaments that hold brush border enzymes for contact digestion)
