Chapter 26 Digestive System

Vocabulary flashcards for the digestive system lecture.

Metabolism

The sum total of all chemical reactions that occur within the body.

Catabolism

The breakdown of large molecules into smaller ones.

Anabolism

The building up of larger molecules from their component parts.

Ingestion

Putting food in your mouth; an active, conscious process.

Mechanical Processing

Physically breaking food into smaller pieces, such as by chewing or churning.

Digestion (Chemical Digestion)

The chemical breakdown of food (catabolism).

Secretion

Release of water, acids, enzymes, buffers, etc., by the digestive tract epithelium and glands.

Absorption

Movement of nutrients across the digestive epithelium into the interstitial spaces.

Excretion

Removal of waste products from body fluids.

Defecation

The act of having a bowel movement.

Feces

The actual waste material.

Peritoneum

The membrane that lines the peritoneal cavity and covers the organs within it.

Visceral Peritoneum

The membrane covering the surface of the abdominal organs.

Parietal Peritoneum

The membrane lining the inner surface of the abdominal body wall.

Peritoneal Fluid

A lubricating fluid that allows the peritoneal membranes to glide past one another without friction.

Retroperitoneal Space

The space separated from the abdominal cavity by the posterior parietal peritoneum; organs in this space are not in the abdominal cavity.

Mesenteries

Double sheets of peritoneal membranes that hold abdominal organs in place.

Lesser Omentum

Connects the stomach and liver and stabilizes the position of both.

Falciform Ligament

Located between the liver and the anterior abdominal wall; stabilizes the liver.

Greater Omentum

Hangs like an apron from the inferior border of the stomach over all of the abdominal organs; accumulates fat and acts as protection (padding) as well as serving to insulate the abdominal cavity.

Peristalsis

Waves of muscular contraction that move small amounts of digestive material (a bolus) along the length of the GI tract.

Segmentation

Contraction of circular muscles in the wall of the GI tract; these contractions break up and churn a bolus rather than pushing it forward.

Oral Cavity (Buccal Cavity)

The mouth; functions include sensory analysis, mechanical processing, lubrication, and limited digestion of carbs and fats.

Vestibule

Area between the cheeks and teeth.

Gingivae

Gums.

Hard Palate

Maxilla and palatine bones.

Soft Palate

Raises up with swallowing to close off the nasopharynx.

Uvula

Dangles at the end of the soft palate – prevents food from entering the pharynx prematurely.

Lingual Frenulum

The thin fold of tissue that connects the body of the tongue to the floor of the oral cavity.

Parotid Salivary Glands

Located at the angle of the jaw; secrete large amounts of salivary amylase.

Salivary Amylase

An enzyme that digests carbohydrates.

Sublingual Salivary Glands

Located under the tongue; secrete mucous for lubrication.

Submandibular Salivary Glands

On the floor of the mouth on the inner surface of the mandible; secrete mucous and salivary amylase.

Incisors

Blade-shaped teeth for clipping or cutting.

Cuspids

Canines; pointed teeth for tearing or slashing.

Bicuspids and Molars

Flattened teeth for grinding or crushing.

Deciduous Teeth

"Baby teeth"; usually 20 teeth.

Secondary Dentition

Permanent teeth; usually 32.

Pharynx

Common passageway for food and air being directed to the esophagus and trachea, respectively.

Esophagus

Hollow muscular tube that conveys solid foods and liquids to the stomach.

Deglutition

Swallowing.

Buccal Phase

The phase of swallowing that begins when the bolus of food is pressed against the hard palate and the tongue aids in moving the bolus into the oropharynx.

Pharyngeal Phase

The phase of swallowing when the bolus enters the oropharynx and the swallowing reflex is initiated.

Esophageal Phase

The phase of swallowing that begins when the bolus is forced through the entrance to the esophagus.

Lower Esophageal Sphincter

Sphincter muscle at the base of the esophagus that relaxes to allow food to enter the stomach but prevents food from being regurgitated into the esophagus (reflux).

Chyme

A thick liquid material is the result of the stomach's churning action that physically breaks down and mixes foods.

Intrinsic Factor

A substance produced by the stomach required for absorption of Vitamin B12.

Pyloric Sphincter

Circular muscle at the end of the stomach separating it from the first part of the small intestine; controls the movement of materials from the stomach into the small intestine.

Parietal Cells

Secrete HCl (hydrochloric acid) which breaks down peptide bonds in proteins

Chief Cells

Secrete pepsinogen, which is an inactive form of the digestive enzyme pepsin; the HCl converts inactive pepsinogen into active pepsin, which is a proteolytic enzyme (breaks down proteins).

Duodenum

10” long; segment of the small intestine closest to the stomach; acts as a “mixing bowl” – receives chyme and digestive secretions from the pancreas and gall bladder

Jejunum

Middle portion of the small intestine; the majority of chemical digestion and nutrient absorption occurs here.

Ileum

Distal segment of the small intestine; attaches to the large intestine

Ileocecal Valve

Another sphincter; between the ileum and the first part of the large intestine called the cecum; controls the flow of digested material into the large intestine

Villi

Finger-like projections of the intestinal mucosa that are covered with columnar epithelial cells with projections called microvilli; this allows for a greatly increased surface area.

Gastroenteric Reflex

Food in the stomach stimulates motility and secretion along the entire small intestine

Gastrocolic Reflex

Food in the stomach triggers the need to defecate

Pancreas

Accessory organ of digestion; produces and secretes digestive enzymes (proteases, carbohydrases or amylases, and lipases) and sodium bicarbonate, which is necessary to neutralize the chyme

Liver

Accessory organ of digestion; metabolic, hematologic regulation and bile production

Bile

Synthesized and secreted; acts as an emulsifier – it breaks large fat droplets into smaller fat droplets thereby increasing the surface area for lipases to act on – bile is not an enzyme

Hepatocytes

Liver cells.

Hepatic Portal System

The nutrient rich venous blood leaving the digestive tract is carried to the liver for processing prior to being dumped into the general venous circulation.

Portal Hypertension

If the blood vessels of the hepatic portal system become blocked the pressure in the portal system will rise causing portal hypertension.

Ascites

Fluids are forced out of the blood vessels and into the surrounding tissues and spaces (essentially into the peritoneal cavity causing a condition known as ascites).

Gallbladder

Accessory organ of digestion; storage of bile synthesized and secreted by the liver.

Cholecystokinin

Hormone released due to fat content of the chyme, causes gallbladder to contract.

Cecum

The first part of the large intestine attached to the small intestine; this is a pouch like structure from which the appendix extends.

Appendix

Serves a digestive function in lower primates, but in humans its function is lymphatic (immune system).

Hepatic Flexure

The turn made as the ascending colon becomes the transverse colon; this happens in the right upper quadrant where the liver is located, hence the name.

Splenic Flexure

The turn where the transverse colon becomes the descending colon; this happens in the left upper quadrant where the spleen is located.

Rectum

temporary storage of feces.

Anus

The opening of the rectum to the outside; this is guarded by two sphincter muscles.