anatomy exam 4

What organs make up the gastrointestinal (GI) tract?

Oral cavity, Pharynx, Esophagus, Small intestine, Large intestine

What are the accessory digestive organs involved in the digestive process?

Teeth, Tongue, Salivary glands, Liver, Gallbladder, Pancreas

What are the six general functions of the digestive system?

Ingestion, Motility, Secretion, Digestion (mechanical and chemical), Absorption, Elimination

What are the four tunics (layers) that make up the gastrointestinal wall?

Mucosa, Submucosa, Muscularis, Serosa/Adventitia

What is absorption in the digestive system?

The process of moving nutrients from the digestive tract into the blood or lymph.

Where does absorption mainly occur?

In the small intestine (duodenum, jejunum, ileum).

What are the transport methods for nutrient absorption?

Simple diffusion, Facilitated diffusion, Active transport, Endocytosis.

How do water-soluble nutrients enter the body?

They pass into blood capillaries, then to the hepatic portal vein and liver.

How do fat-soluble nutrients enter the body?

They enter lacteals (lymphatic capillaries) and eventually the bloodstream.

What is the function of the muscularis mucosae?

Produces peristalsis and segmentation to move food along the GI tract.

What is the function of the muscularis tunic?

Moves the mucosa locally to enhance contact with lumen contents, aiding absorption and secretion.

What is the role of the enteric nervous system (ENS) in digestion?

Coordinates reflexes for mixing and propulsion from esophagus to anus.

What does the autonomic nervous system (ANS) do for the GI tract?

Parasympathetic innervation promotes activity, while sympathetic innervation opposes it.

What is the function of gastrin?

Increases secretions from parietal and chief cells in the stomach.

What does somatostatin do?

Inhibits pancreatic juice release and gastric juice secretion.

What is the function of cholecystokinin (CCK)?

Stimulates gallbladder contraction and increases pancreatic juice output.

What does secretin do?

Inhibits stomach motility and increases bicarbonate output from liver and pancreas.

What are the components of the upper gastrointestinal tract?

Includes the peritoneum, which is the largest serous membrane of the body.

What is the difference between retroperitoneal and intraperitoneal organs?

Retroperitoneal organs are located behind the peritoneum, while intraperitoneal organs are within the peritoneal cavity.

What is the function of the mesentery?

Supports and suspends abdominal organs, houses blood vessels, nerves, and lymphatics.

What is the function of the mesentery proper?

Supports small intestines; carries blood vessels, nerves, lymphatics.

What does the transverse mesocolon connect?

Connects transverse colon to posterior abdominal wall.

What is the function of the sigmoid mesocolon?

Supports sigmoid colon; carries vessels and nerves.

What does the mesocolon of ascending and descending colon connect?

Connects ascending and descending colon to posterior abdominal wall.

What is the function of the falciform ligament?

Anchors liver; contains ligamentum teres (remnant of umbilical vein).

What is the role of the tongue in the oral cavity?

Accessory digestive organ that maneuvers food for chewing and swallowing.

What do salivary glands secrete?

Saliva, which keeps the mouth and pharynx moist and clean.

What triggers salivation?

Receptors detect stimuli (especially acids) in oral cavity and stomach.

What are the two enzymes secreted by salivary glands?

Salivary amylase (carbs) and lingual lipase (lipids).

What is the primary mass of a tooth?

Dentin.

What is the hardest substance in the body?

Enamel.

What fills the pulp cavity of a tooth?

Gelatinous pulp.

What are deciduous teeth?

Baby teeth that appear around 6 months old.

What are the two types of cells in salivary glands?

Serous cells (secrete watery fluid) and mucous cells (secrete mucin).

What is the histology of the pharynx?

Nonkeratinized stratified squamous epithelium.

What regulates the movement of food from the pharynx into the esophagus?

Superior (upper) esophageal sphincter.

What is the function of the inferior (lower) esophageal sphincter?

Regulates movement of food from esophagus into stomach.

What are the phases of deglutition?

Voluntary phase, pharyngeal phase (involuntary), esophageal phase (involuntary).

What is the function of gastric mixing?

Mechanical digestion that mixes bolus with gastric secretions to form chyme.

What is the role of the pyloric sphincter?

Regulates gastric emptying by opening to allow chyme into the duodenum.

What stimulates digestive processes in the stomach?

Parasympathetic nervous system and gastrin.

What is the histology of the esophagus?

Stratified squamous epithelium.

What is the function of saliva?

Moistens food, initiates chemical breakdown of starch and lipids, cleanses oral cavity.

What are the components of saliva?

99.5% water and 0.5% solutes (ions, gases, urea, mucus, IgA, lysosome, amylase, lipase).

What is the function of gastric glands in the stomach?

Helps expel gastric secretions.

What is the primary function of the stomach?

Gastric mixing and gastric emptying.

What is the role of the gastric pits?

Depressions in lining that lead to gastric glands.

What is the function of the root canal in a tooth?

Continuous with pulp cavity, opens to tissue around root.

What is the function of gingivae (gums)?

Covers alveolar processes and surrounds neck of teeth.

What is the role of the soft palate during swallowing?

Closes off the nasopharynx.

What is the function of the epiglottis during swallowing?

Closes over laryngeal inlet to prevent food from entering the airway.

What is the small intestine?

A long tube inferior to the stomach located medially in the abdominal cavity.

What are the three regions of the small intestine?

Duodenum, jejunum, ileum.

What increases the surface area of the small intestine?

Circular folds, villi, and microvilli.

What are circular folds in the small intestine?

Mucosal and submucosal tunics that slow down the movement of chyme.

What are villi?

Fingerlike projections of the mucosa that contain a capillary network and lacteals.

What are microvilli?

Extensions of the plasma membrane that form a brush border with enzymes.

What do intestinal glands secrete?

Intestinal juice.

What do goblet cells secrete?

Mucin.

What do enteroendocrine cells release?

CCK and secretin.

What do Paneth cells secrete?

Lysosomes and other antimicrobial agents.

What is the function of the duodenal submucosal gland?

Produces alkaline mucus for protection.

What is segmentation in the small intestine?

A back and forth motion that mixes chyme with secretions.

What is peristalsis?

A forward motion that propels material within the GI tract.

What is the exocrine function of the pancreas?

Secretion of pancreatic juice containing enzymes and bicarbonate.

What ducts deliver pancreatic secretions to the duodenum?

Pancreatic duct and accessory pancreatic duct.

What is the primary function of the liver?

To produce bile.

What does the gallbladder do?

Stores and releases bile.

What is the common bile duct?

Carries bile and pancreatic juice to the duodenum.

What hormone allows bile and pancreatic juice to flow into the duodenum?

CCK.

What is the hepatic portal system?

Transports blood from digestive organs to the liver.

What are the functions of the liver?

Produce bile, plasma proteins, detoxify blood, store vitamins and minerals, and regulate metabolism.

What is the endocrine function of the pancreas?

Produces hormones.

What are acinar cells?

Modified simple cuboidal epithelial cells that produce digestive enzymes.

What regulates the pancreas?

Secretin and CCK, along with vagus nerve stimulation.

What are the three major regions of the large intestine?

Cecum, colon, rectum.

What are the four segments of the colon?

Ascending colon, transverse colon, descending colon, sigmoid colon.

What histologic features distinguish the large intestine?

Lined with simple columnar epithelium and numerous goblet cells.

What is the gut microbiome?

Bacterial flora in the large intestine responsible for breaking down complex carbohydrates and producing vitamins.

What are the three classes of carbohydrates?

Polysaccharides, disaccharides, and monosaccharides.

What initiates carbohydrate digestion in the oral cavity?

Salivary amylase.

How is carbohydrate digestion completed?

In the small intestine.

What is the role of salivary amylase?

It begins the digestion of carbohydrates in the oral cavity.

Why are proteolytic enzymes synthesized as zymogens?

To prevent them from digesting proteins in the cells where they are produced.

What is pepsin and how is it activated?

Pepsin is an enzyme that digests proteins, activated from pepsinogen by hydrochloric acid in the stomach.

What role does pepsin play in protein digestion?

It breaks peptide bonds, producing smaller polypeptides for further digestion.

What enzymes are involved in protein digestion in the small intestine?

Trypsin, chymotrypsin, and carboxypeptidase.

What is the function of bile salts in lipid digestion?

They emulsify lipids to aid in their mechanical digestion.

How are lipids absorbed in the small intestine?

Lipids form micelles for transport and are wrapped into chylomicrons for absorption.

What are micelles?

Micelles are structures that transport lipids in the lumen of the small intestine.

What is the process of vitamin B12 absorption?

B12 is released in the stomach, binds to intrinsic factor, and is absorbed in the ileum.

What are macronutrients?

Nutrients required in large amounts, including carbohydrates, lipids, and proteins.

What are micronutrients?

Nutrients required in smaller amounts, including vitamins and minerals.

What is the difference between essential and nonessential nutrients?

Essential nutrients must be obtained from the diet, while nonessential nutrients can be synthesized by the body.

What are complete proteins?

Proteins that contain all nine essential amino acids.

What are incomplete proteins?

Proteins that do not contain all essential amino acids.

What is nitrogen balance?

The difference between nitrogen intake and loss in the body.

What is positive nitrogen balance?

When nitrogen intake is greater than nitrogen loss, indicating protein synthesis.

What is negative nitrogen balance?

When nitrogen loss exceeds nitrogen intake, indicating protein breakdown.

What is zero nitrogen balance?

When nitrogen intake equals nitrogen loss, indicating equilibrium.