digestive system practical

alimentary canal/gi tract - 6

mouth

pharynx

esophagus

stomach

small intestines

large intestines

accessory structures - 1 def, 5. structures

def. secrete their products into the canal

teeth

salivary glands

gallbladder

liver

pancreas

mucosa - 3 subdivisions

Epithelium [innermost] -> strat. squamous in mucosas/anus/mouth epithelium, simple columnar in the rest of the canal

Lamina Propria -> areolar CT w/ blood vessels, lymphoid follicles, MALT

Muscularis Mucosae [outermost] -> smooth muscle

mucosa function [sap]

secrete mucus, digestive enzymes, hormones

absorb end products

protect against disease

submucosa tissue/function - 3

tissue: CT, blood/lymph vessels, and nerve fibers

function:

• blood vessels absorb and transport nutrients,

• elastic fibers maintain the shape of each organ

muscularis externa sub/tissue - 2

circular -> inner layer of smooth muscle

longitudinal -> outer layer of smooth muscle

muscularis function

peristalsis of digested food

serosa 2 layers

CT -> areolar CT

epithelium -> simple squamous epithelium

gastroesophageal junction - 3

controls food passage into the stomach

esophagus: stratified squamous (to withstand abrasion)

stomach: simple columnar (for secretional products)

stomach - 2

located in upper left quadrant

has a 3rd muscle layer that allows it to churn adn pummel food

mesentery - 3

double layer of peritoneum (a sheet of 2 serous membranes fused together) that extend from the organs to the body wall

2 types:

greater omentum

lesser omentum

greater omentum

extends from the greater curvature of the stomach adn covers most of the abdominal organs

lesser omentum

extends from the liver to the lesser curvature of the stomach

cardiac stomach - 3

surrounds cardiac orifice where food enters the stomach

stratified squamous: esophagus

simple columnar: stomach

fundic stomach- anatomy & 2 cells

dome shaped area

parietal cells- HCL, intrinsic factors, red stained

chief cells- pepsinogen, blue stained

pyloric stomach - 3

stomach exits into duodenum

most digestive activity occurs here

has deep gastric pits and glands

mucosal glands

secrete a viscous mucus that prevents the stomach itself from being digested

chief cells - 2

produce pepsinogen

blue

parietal cells - 2

secrete HCL and intrinsic factors

red

3 Structures that inc Absorptive Surface of Small Intestine Mucosa:

microvilli

villi

circular folds

circular folds

force chyme to spiral through intestine, slowing its progress

duodenum features - 4

long villi

brunner’s gland

duodenal glands : produe mucus

intestinal crypts : produce intestinal juice

ileum cells - 4

Peters Patches- lymphoid follicles that inc along length of canal

Mucosa-Associated Lymphoid Tissues (MALT)

villi are shorter

large intestine 5 subdivisions: (cacra)

cecum, appendix, colon, rectum, and anal canal.

anal canal 2 sphincters - 2

- a voluntary external anal sphincter composed of skeletal muscle

- an involuntary internal anal sphincter composed of smooth muscle

only opened during defecation

large intestine 3 functions

1. Consolidate and propel unusable fecal mater towards anus.

2. Absorb water

3. Absorption of vitamins such as B and K which are produced by gut bacteria.

bile - 3

emulsifies fats, breaking up gat globules into small droplets

without it, very little fat digestion or absorption

Bile flows in the opposite direction toward the bile ducts.

liver lobule 3 components

Hepatic artery branch (oxygenated blood)

Hepatic portal vein branch (nutrient-rich blood)

Bile duct

digestion

food being broken into smaller diffusible molecules

absorption

digested products passing through epithelial cells into blood for distribution