Histology and Function of the GI Tract

Mucosa layer components

Epithelium, lamina propria, smooth muscle

Stratified squamous epithelium locations

Mouth, esophagus, anal canal

Function of the submucosa

Nutrition and vascular supply

Muscularis externa function

Responsible for peristalsis and segmentation

Function of the serosa

Structure and protection

Nervous system controlling digestion

Autonomic nervous system

Intrinsic nervous system function

Regulates function through local nerve plexuses

Parasympathetic nervous system effect

Stimulates digestion (increases salivation, enzyme secretion, and smooth muscle contraction)

Sympathetic nervous system effect

Suppresses digestion

Enzyme in saliva for carbohydrate digestion

Salivary amylase

Number of salivary gland pairs in humans

Three

Percentage of saliva that is water

99.5%

Nervous system increasing saliva secretion

Parasympathetic nervous system

Esophagus epithelium type

Stratified squamous epithelium

Function of rugae in the stomach

Increase surface area

Stomach epithelium type

Simple columnar epithelium

Substance secreted by parietal cells

HCl and intrinsic factor

Inactive enzyme secreted by chief cells

Pepsinogen

Function of HCl in the stomach

Denatures proteins for digestion

Partially digested food leaving the stomach

Chyme

Function of sodium bicarbonate from the pancreas

Neutralizes acidic chyme

Exocrine pancreas secretion

Amylase, trypsin, lipase, and sodium bicarbonate

Non-function of the liver

Secretion of digestive enzymes

Function of bile

Emulsifies fats

Regenerative liver cells

Hepatocytes

Small ducts collecting bile in the liver

Bile canaliculi

Purpose of peristalsis

Move food along the digestive tract

Extra layer of smooth muscle in the stomach

Helps with mechanical digestion

Role of intrinsic factor in digestion

Helps absorb Vitamin B12

Pancreas protection of small intestine

Secreting sodium bicarbonate