the digestive system.

Digestion, absorption, and elimination.

1. Mucosa: innermost
2. Submucosa: (connective tissue) contains nerves and blood vessels
3. Muscularis: muscle layer. Muscle type: smooth, (2) layers: circular and longitudinal (nerves B/T)
4. Serosa: outermost covering (visceral peritoneum)

Layers modified according to organ’s function.

Lips: (philtrum) shallow vertical groove (oral fissure) line contact between closed lips
Cheeks: (buccinator muscle) major cheek muscle (buccal gland) mucous glands
Tongue: 2 types of muscle: extrinsic- insertion into tongue, origin in other structures. Moves tongue as whole. Intrinsic- origin and insertion within tongue.
Hard palate- bone (2 maxillary and 2 palatine
Soft palate- muscle behind the hard palate (fauces and uvula)

Buccal glands: less than 5% of the total volume of saliva
Paired salivary glands: (3 pairs) secrete major portion 95% of saliva

1. Parotid: largest of all and contain enzymes but no mucous (stensen’s duct)
2. Submandibular: contains both enzymes and mucous (Wharton’s duct)
3. Sublingual: smallest and contain only mucous

crown:visible portion of tooth
neck: narrow portion surrounded by gingivae.
root: hidden portion held by periodontal membrane.

baby teeth and there are 20 in total
numbers per jaw:
incisors:4
central 2
lateral:2
canines:2
molars:4

adult teeth and there are 32 in total generally erupt between 7-24 years
numbers per jaw:
incisors: 4
central-2
lateral-2
canines: 2
premolars: 4 (1 & 2)
molars: 6 (1,2 & 3)

enamel: covers crown of tooth, most chemically stable (minerals)
dentin: greatest portion of the tooth shell
cementum: outermost dental tissue in the neck and root area

cavity located within dentin it contains connective tissue, blood vessels, and sensory nerves.

its a shared organ between the respiratory and digestive system.

it extends from pharynx and stomach
and it lies posterior to trachea and heart.
layer modification:
1. mucosa
2. muscularis: inner, circular and outer. longitudinal
2 types: skeletal and smooth

size various according to numerous factors:
1. gender
2. amount distention
shape: pouchlike
position: epigastric and left hypochondriac regions (5/6 to left)

fundus: enlarged upper portion
lies above where esophagus opens into stomach
body: central portion
pylorous: lower narrow portion

lesser curvature: upper surface of the stomach (smaller)
greater curvature: lower surface of stomach (larger)

cardiac sphincter- controls food entering the stomach.
pyloric sphincter- located between stomach and small intestine. it controls materials exiting the stomach.

mucosa- rugae, gastric pits and mucous cells, gastric glands.
muscularis- smooth- inner oblique, middle circular, outer longitudinal muscle layers.
serosa- visceral peritinium
greater omentum & lesser omentum

1. food reservoir
2. secretes gastric juices
3. churns and mixes
4. secretes instrinsic factor
5. limited amount of absorption
6. produces gastrin
7. defense (hcl acid destroys bacteria)

1" in diameter and 20' in length
lies between stomach and large intestine.
divisions:
duodenum-shaped like letter c
jejunum- middle portion
ileum- last &longest

1. mucosa: plica circularis, villi , contains (arteriole, venule, lacteal) & microvilli (brush border cells)
all increase surface area.
muscularis
serosa

cecum-lower right quadrant
colon- second portion has 4 divisions
rectum- last portion (anal canal, internal and external anal sphincter)

ascending colon-
transverse colon-
sigmoid colon-

ileocecal valve
ascends vertically on the right side of the abdomen.

hepatic flexure to splenic flexure. extends horizontally across the abdomen.

descends vertically on the left side of the abdomen. (extends to the top of the pelvic bone)

"s" shaped bends towards the left as it joins the rectum.

folds of the mucous lining of anal canal and each contain an artery and a vein; allows for expansion (defecation)

internal- smooth muscle
external- skeletal muscle
involved in defecation.

mucosa
muscularis
serosa