Anatomy and Physiology II- Exam 4

Gastroenterology

study of the stomach and intestines

Gastrointestinal tract (GI tract)

a long tube, about 25 feet in length; open at both ends for the transit of food during processing; includes the:

1. mouth

2. pharynx

3. esophagus

4. stomach

5. small intestine

6. large intestine

7. rectum

8. anal canal

Accessory structures

structures that contribute to the food processing; include:

1. teeth and tongue

2. salivary glands

3. liver

4. gallbladder

5. pancreas

Mechanical digestion

physical breakdown of large pieces of food into smaller pieces; mixing waves

Chemical digestion

breaking down food with enzymes; catabolic process; primarily accomplished with pepsin

Steps of digestion

1. ingestion

2. secretion

3. mixing and propulsion

4. digestion

5. absorption

6. defecation

Ingestion

taking food into the mouth (eating)

Secretion

the release of water, acid, buffers, and enzymes into the lumen of the GI tract; accomplished by both the GI tract cells and accessory organs

Mixing and propulsion

alternating contraction and relaxation of the smooth muscles within the walls of the GI tract

Digestion

consists of mechanical and chemical digestion

Absorption

the passage of these digested molecules from the lumen of the GI tract, across the wall of the tract, and into the underlying blood or lymph for distribution to cells throughout the body

Defecation

the emptying of the rectum to eliminate indigestible substances from the GI tract; elimination of feces from the digestive tract through the anus

Mucosa, submucosa, muscularis, serosa

four tissue layers that make up the GI tract

Mucosa

inner layer of GI tract tissue; consists of the epithelium, lamina propria, and muscularis mucosa

Epithelium, lamina propria, muscularis mucosa

three layers of the mucosa

Epithelium

inner layer of the mucosa; that lines from the mouth to the esophagus; non-keratinized stratified squamous cells; simple columnar epithelium lines the stomach and intestines are needed for secretion and absorption; also includes goblet cells and enteroendocrine cells

Mouth, esophagus

from the _______ through the _______ is lined with non-keratinized stratified squamous epithelial cells

Stomach, intestines

the ______ and _______ are lined with simple columnar epithelium that aid in secretion and absorption

Goblet cells

mucus secreting cells

Enteroendocrine cells

hormone secreting cells that help regulate digestion; located in the mucosa;

1. CCK cells

2. S cells

3. K cells

Lamina propria

second layer of the mucosa; contain blood and lymph vessels, nerves, connective tissue, and MALT cells; aid in immunity

Mucosa-associated lymph tissue

MALT cells; aids in immunity

Muscularis mucosa

outer layer of the mucosa; allows for local, independent movement; contraction aids in secretion; includes rugae and plicae

Rugae

temporary folds in the stomach lining

Plicae

permanent folds that remain regardless of distension; in the small intestines

Submucosa

second layer of the GI tract; loose connective tissue with lots of blood and lymph vessels; contains the submucosal plexus which controls GI secretions

Submucosal plexus

"brains of the gut" part of the enteric nervous system; controls secretion of the GI tract

Muscularis

the third layer of the GI tract; involved in voluntary swallowing and involuntary peristalsis and segmentation

Skeletal muscles

muscles that lines the mouth, pharynx, and superior part of the esophagus which control voluntary swallowing and also forms the external anal sphincter

Smooth muscles

muscles that lines the GI tract from the middle of the esophagus to the anus; includes circular and longitudinal fibers; creates peristalsis and segmentation

Peristalsis

coordinated muscular contractions that move food boluses through the GI tract; occur behind the bolus to push it forward; governed by hormones and neurons

Segmentation

alternating contractions and relaxations of the circular layer of the muscularis; mixes food with digestive enzymes that have been secreted and increases contact between bolus and mucosa

Myenteric plexus

located between the inner circular and outer longitudinal muscle layers; controls that strength frequency of the muscular contractions

Serosa

outermost layer of the GI tract; also the visceral peritoneum; secretes slippery, watery (serous) fluid

Peritoneum

the serous membrane in the abdominal cavity; largest serous membrane in the body

Parietal peritoneum

portion of the peritoneum that lines the wall of the abdominal cavity

Visceral peritoneum

portion of the peritoneum that covers the organs and constitutes their serosa

Peritoneal cavity

the space between the parietal and visceral peritoneum; contains a small amount of serous fluid

Greater omentum

tissue that extends from the greater curvature of the stomach and drapes down over the anterior small intestines and then doubles back to attach to the transverse colon

Lesser omentum

tissue that extends from the liver to the lesser curvature of the stomach

Falciform ligament

tissue that attaches the liver to the anterior body wall and separates the left and right lobes of the liver

Mesentery

attaches the small intestine to the posterior wall of the abdomen

Mesocolon

attaches the colon to the posterior wall

Retroperitoneal

the region posterior to the abdominal peritoneum; include the SAD PUCKER organs

Peritonitis

acute inflammation of the peritoneum

SAD PUCKER

suprarenal glands, aorta, duodenum, pancreas, ureters, colon, kidneys, esophagus, rectum; located at the retroperitoneal

Stratified squamous epithelium

the mouth is lined with ____________ which provides protection against abrasion and high temperatures

Tongue

a skeletal muscle covered in mucous membrane; forms the floor of the oral cavity

Lingual frenulum

fold of mucous membrane that attaches to the midline of the undersurface of the tongue; offers support to aid in movement

Superior labial frenulum

mucosal fold connected to upper lip

Inferior labial frenulum

mucosal fold connected to lower lip

Uvula

the part of the soft palate that hangs down in the back of the throat; prevents food from entering the nasal cavity

Gingivae

gums

Salivary glands

three extrinsic: parotid, submandibular, sublingual; produce saliva which aids in lubrication, dissolving food, protection, and taste

Parotid gland

largest salivary gland; located in the cheek

Submandibular gland

salivary gland located under the jaw

Sublingual gland

salivary gland under the tongue

99, 1

saliva is ______% water, ______% solutes and enzymes

Lysozyme

enzyme in saliva that kills bacteria

Salivary amylase

enzyme in saliva that breaks down starch

P-ANS

division of the nervous system that has primary control over salivation; produces thinner saliva with more enzymes

S-ANS

division of the nervous system that stimulates thicker saliva that contains more mucus and less digestive enzymes

Mumps

an inflammation and enlargement of the parotid salivary glands, caused by the mumps virus; symptoms include fever, malaise, pain, swelling of the glands, and possible sterility in adult males

Mastication

the process of chewing; mixing the food and creating a bolus of food

Bolus

food that has been chewed, mixed with saliva and made into a clump which can travel down the GI tract to the stomach

Chemical

the only ________ digestion in the mouth is caused by the enzymes in the saliva

Deglutition

the process of swallowing

Emesis

vomiting

Voluntary

from the mouth to the pharynx, it is ________ swallowing

Skeletal, mucous

the pharynx is composed of _______ muscle and _______ membrane

Nasopharynx

upper part of the pharynx; aids in respiration only

Oropharynx

central part of the pharynx; aids in digestion and respiration

Laryngopharynx

lower part of the pharynx; aids in digestion and respiration

Esophagus

a collapsible, muscular tube that is posterior to the trachea and connects the pharynx to the stomach; lined with stratified squamous epithelium for protection; secretes mucus with no enzymes

Skeletal, skeletal and smooth, smooth

the upper 1/3 of the esophagus is ________ muscle

the middle 1/3 of the esophagus is ________ and _______ muscle

the lower 1/3 of the esophagus is _______ muscle

Upper esophageal sphincter (UES)

the muscular ring located at the top of the esophagus that prevents food from entering the mouth

Lesser esophageal sphincter (LES)

muscular ring located at the bottom of the esophagus that prevents food from leaving the stomach and entering the esophagus; when it dysfunctions, it causes GERD

Gastroesophageal reflux disease

GERD; upward flow of acidic substances from the stomach into the esophagus; causes a burning feeling in the chest

Swallowing stages

1. voluntary stage

2. pharyngeal stage

3. esophageal stage

Voluntary stage

first stage of swallowing; the tongue helps force food bolus into the esophagus

Pharyngeal stage

second stage of swallowing; breathing is temporarily interrupted as food passes through the oropharynx into the esophagus; the soft palate and uvula close of the nasopharynx and epiglottis and vocal cords prevent pulmonary aspiration

Pulmonary aspiration

"food going down the wrong pipe" into the trachea/lungs; prevented by the epiglottis closing off the larynx and the vocal cords closing to block off the trachea

Esophageal stage

third stage of swallowing; the food bolus passes through the esophagus into the stomach via peristalsis

Circular, longitudinal

during peristalsis, _______ muscle fibers above the bolus squeeze the bolus forwards and _______ muscle fibers around the bottom of the bolus contract, shortening and widening the lumen of the esophagus at the region the bolus is entering

Stomach

J-shaped, muscular pouch that expands to hold chyme

pyloric sphincter

a ring of muscle at the end of the stomach that controls food leaving the stomach

Chyme

food that is in the stomach and has already been mixed with digestive enzymes

Cardia

the upper opening of the stomach where the esophagus enters the stomach

Fundus

the upper portion of the stomach

Body

the main part of the stomach

Pylorus

distal region of the stomach, opening to the duodenum

Gastric rugae

temporary, visible folds on the inner stomach which allow the walls to stretch

Pylorospasm

condition of the pyloric sphincter in newborns where the pyloric sphincter involuntarily contractions

Pyloric stenosis

condition of the pyloric sphincter in newborns where the pyloric sphincter is too big and limits amount of food that enters the duodenum; causes projectile vomiting

Gastric pits

invaginations of the surface epithelium into the lamina propria; lined with surface mucous cells; lead to gastric glands

Surface mucous cells and mucus neck cells

mucous secreting cells on the surface of the mucosa which produce a cloudy, viscous, alkaline mucus that forms a thick gel-like coat that adheres to the surface epithelium to protect from abrasions and acidic gastric juices

Exocrine

glands that secrete their products through ducts into an open lumen/epithelium

Endocrine

glands that secrete hormones or other products directly into the blood

Paracrine

cells that secrete substances that act on adjacent cells

Autocrine

cells that secrete substances that act of that same cell