Digestive anat 2

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GI tract (Alimentary Canal)

Muscular tube extending from the mouth to the anus that is open to the external environment.

Accessory digestive organs

Organs that aid in the breakdown of food.

Mucosa

The innermost layer of the digestive tract, consisting of Epithelium, Lamina propria, and Muscularis mucosae.

Epithelium layer of GI Mucosa

Simple columnar epithelium in the stomach and intestines; non-keratinized stratified squamous epithelium from the oral cavity to the esophagus and in the lower anal canal.

Lamina propria layer of GI Mucosa

Loose connective tissue containing mucosa-associated lymphoid tissue (MALT) with lymphocytes and lymphatic nodules, including Peyer's patches in the distal ileum.

Muscularis mucosae layer of GI Mucosa

Thin layer of smooth muscle that tenses the mucosa to enhance surface area.

Submucosa

Thicker layer of loose connective tissue containing blood vessels, lymphatics, nerve plexus, and potentially glands and MALT.

Muscularis externa

GI tract wall layer typically composed of inner circular and outer longitudinal muscle layers responsible for motility and propulsion.

Submucosal (Meissner) plexus

Enteric nerve plexus situated in the submucosa that controls glandular secretions and muscularis mucosae movement.

Myenteric (Auerbach) plexus

Enteric nerve plexus located between the smooth muscle layers that regulates peristalsis and contractions of the muscularis externa.

Serosa

Outermost membrane layer in the abdominal cavity composed of thin areolar tissue and mesothelium (visceral peritoneum).

Adventitia

Fibrous connective tissue layer replacing serosa in the pharynx, most of the esophagus, and the rectum.

Parietal peritoneum

Serous membrane layer that lines the wall of the abdominal cavity.

Visceral peritoneum

Serous membrane layer that directly envelops abdominal organs.

Peritoneal cavity

Fluid-filled space between the parietal and visceral layers of the peritoneum.

Intraperitoneal

Classification for organs completely enclosed by visceral peritoneum/serosa.

Retroperitoneal

Classification for organs covered by peritoneum only on their anterior surface.

Greater omentum

Apron-like peritoneal fold superficial to the small intestine and transverse colon; serves as a major site of fat deposition.

Mesentery

Vertical band of tissue anterior to the lumbar vertebrae that anchors all of the small intestine except the initial portion (duodenum).

Mesocolon

Peritoneal fold that attaches the transverse and sigmoid colon to the posterior abdominal wall.

Ingestion

The process of taking food into the digestive tract through the mouth.

Mastication

The physical process of chewing food.

Propulsion

Movement of food through the digestive tract via voluntary deglutition (swallowing) and involuntary peristalsis.

Mechanical digestion

Physical breakdown of food that yields smaller pieces and increased surface area.

Chemical digestion

Enzymatic breakdown of complex food molecules into simple chemical building blocks.

Absorption

Process by which nutrients and water pass from the GI tract lumen into the bloodstream.

Defecation

Elimination of undigested materials from the body as feces.

Hard palate

Bony structure that separates the oral and nasal cavities.

Soft palate

Muscular structure at the roof of the mouth that is manipulated during swallowing.

Uvula

Projection hanging from the soft palate that helps prevent food and fluid from entering the nasal cavity during swallowing.

Papillae containing taste buds

Fungiform and circumvallate papillae.

Gingivae

Gums surrounding the necks of the teeth.

Pulp cavity

Central region of a tooth containing loose connective tissue, blood vessels, and nerves.

Dentin

Bone-like material surrounding the pulp cavity of a tooth.

Enamel

Hardest substance in the body, forming the outer layer of the tooth crown.

Salivary amylase

Digestive enzyme in saliva that initiates carbohydrate digestion.

Autonomic regulation of salivation

Parasympathetic stimulation increases salivation, while sympathetic stimulation decreases salivation.

Nasopharynx

Pharyngeal region involved only in breathing and speech.

Oropharynx and Laryngopharynx

Pharyngeal regions involved in both breathing and digestion.

Esophagus histology

Lined with non-keratinized stratified squamous epithelium with mucus-secreting glands, featuring adventitia as its outermost layer.

Esophagus muscular composition

Upper third is skeletal muscle, middle third is mixed skeletal and smooth muscle, and lower third is smooth muscle.

Oral phase of deglutition

Voluntary step of swallowing where the tongue pushes the food bolus into the oropharynx.

Pharyngeal phase of deglutition

Involuntary step of swallowing where the soft palate closes off the nasopharynx, epiglottis covers the larynx, and the upper esophageal sphincter opens.

Esophageal phase of deglutition

Involuntary step of swallowing where peristalsis propels food and the lower esophageal sphincter opens to enter the stomach.

Peristalsis

Sequential, alternating waves of contraction and relaxation of alimentary wall smooth muscles that propel food along the GI tract.

Regions of the stomach

Cardia (entrance), fundus (superior dome), body (main central portion), and pylorus (funnel region connecting to the duodenum).

Pyloric sphincter

Ring of smooth muscle that controls the emptying of stomach contents into the duodenum.

Rugae

Mucosal folds within the stomach that allow it to expand when filled with food.

Stomach muscularis externa adaptation

Possesses a third inner oblique smooth muscle layer that assists in mechanical churning of food.

Gastrin

Hormone secreted by enteroendocrine G cells in response to food that stimulates parietal and chief cell secretions and increases intestinal motility.

Parietal cell secretions

Hydrochloric acid (HCl), which lowers pH to activate pepsin and kill microbes, and intrinsic factor, essential for vitamin B12 absorption.

Chief cell secretions

Pepsinogen (inactive enzyme precursor converted to pepsin for protein digestion) and gastric lipase (for fat digestion).

Mucous neck cells

Gastric gland cells that secrete protective mucus to shield the stomach wall from pepsin and hydrochloric acid.

Regions of the small intestine

Duodenum, jejunum, and ileum.

Small intestine surface area adaptations

Circular folds (plica circulare), villi (containing capillaries and lacteals), and microvilli (brush border containing digestive enzymes).

Duodenal (Brunner's) glands

Glands restricted to the duodenum that produce bicarbonate-rich mucus to buffer acidic chyme.

Secretin

Hormone released by small intestine enteroendocrine cells in response to acidic chyme that stimulates pancreatic bicarbonate release and hepatic bile secretion.

Cholecystokinin (CCK)

Hormone released by small intestine enteroendocrine cells in response to fatty chyme that triggers gallbladder contraction and pancreatic juice secretion.

Segmentation

Localized smooth muscle contractions in the intestine that mix and churn chyme to provide time for digestion and absorption.

Migrating motility complexes

Form of peristalsis in the small intestine that propels residual material along the tract between meals.

Regions of the large intestine

Cecum (with attached appendix), colon (ascending, transverse, descending, sigmoid), rectum, and anus.

Order of movement through the large intestine

Cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum.

Teniae coli and Haustra

Teniae coli are three longitudinal smooth muscle bands in the large intestine that gather the wall into pouches called haustra.

Epiploic appendages

Fat-filled sacs of visceral peritoneum attached to the large intestine.

Anal sphincters composition

Internal anal sphincter is composed of involuntary smooth muscle, while external anal sphincter is composed of voluntary skeletal muscle.

Functions of the liver

Storage of glycogen, vitamins (A, D, E, K), and minerals (iron and copper), detoxification of chemicals like ammonia, and bile production.

Porta hepatis vascular supply

Hepatic artery (oxygenated blood), hepatic portal vein (nutrient-rich deoxygenated blood from intestines), and hepatic vein (drains blood to IVC).

Hepatocytes

Primary liver cells making up 80% of liver volume that produce bile and process nutrients, toxins, and wastes.

Kupffer cells

Hepatic phagocytes located in sinusoids that eliminate old blood cells, bacteria, and foreign debris.

Portal triad

Structure located at the corners of hepatic lobules containing a bile duct branch, a hepatic artery branch, and a hepatic portal vein branch.

Biliary duct system

Hepatic ducts drain bile from the liver, the cystic duct empties bile from the gallbladder, and both join to form the common bile duct which empties into the duodenum.

Emulsification

Physical breakdown of large lipid droplets into smaller globules by bile salts, increasing surface area for enzymatic digestion.

Pancreatic juice components

Water, sodium bicarbonate (acid buffer), trypsinogen and chymotrypsinogen (proteases), pancreatic amylase, pancreatic lipase, and nucleases.

Pancreatic ducts

The larger pancreatic duct merges with the common bile duct and empties into the duodenum at the hepatopancreatic ampulla, while the smaller accessory duct empties directly into the duodenum.

peritoneum.

The greater omentum is part of the

uvula

The projection hanging from the soft palate that helps prevent food and fluid from entering the nasal cavity during swallowing is the

carbohydrates.

Salivary amylase is an enzyme secreted into the oral cavity to start the digestion of

dentin.

Teeth are primarily composed of a bone-like substance called

stomach.

The digestion of proteins into peptides starts in the

cholecystokinin.

The hormone secreted by intestinal glands that inhibits gastric emptying is

duodenum.

Chyme is released from the stomach into the

duodenum.

The pancreatic duct transports pancreatic juice from the pancreas into the.

hepatocytes.

Bile is produced by

small intestine.

The major events of chemical digestion and absorption of foods occur in the

ileum.

The final portion of the small intestine, which is mostly found in the lower right quadrant, is called the

cecum.

The first portion of the large intestine is called the

sigmoid colon.

The portion of the large intestine just before the rectum is the

ascending colon.

Most of the nutrients have been absorbed from the chyme by the time it reaches the

cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum

Which of the following lists the correct order of movement of digestive material through the large intestine?

liver

Storage of glycogen, vitamins (A, D, E, K), and minerals (iron and copper), along with detoxification of chemicals like ammonia, are functions of the