Fundamentals of Anatomy & Physiology: A&P II Chapter 24: The Digestive System Flashcards

nutrients are used as raw materials for synthesizing essential compounds

decomposes substances to provide energy cells need to function

-requires two essential ingredients

1. Oxygen
2. Organic molecules ( such as carbohydrates, fats, and proteins) broken down by intracellular enzymes

• aka the gastrointestinal (GI) tract or alimentary canal
• is a muscular tube
• includes the mouth, pharynx, esophagus, stomach, and small and large intestines
• extends from the oral cavity to the anus

• teeth
• tongue
• salivary glands
• liver
• gallbladder
• pancreas

1. Ingestion
2. Mechanical Processing
3. Digestion
4. Secretion
5. Absorption
6. Excretion

• takes place when materials enters the oral cavity

• crushing and shearing, making materials easier to move along the digestive tract

• the chemical breakdown of food into small organic fragments for absorption by digestive epithelium

• the release of water, acids, enzymes, buffers, and salts by the epithelium of the digestive tract & glandular organs

• the movement of organic substrates, electrolytes, vitamins, and water across digestive epithelium and into interstitial fluid of the digestive trace

the removal of wastes from the body

*defecation

ejection of wastes from the digestive tract eliminating them as feces

covers organs within peritoneal cavity

lines inner surfaces of body wall

• produced by the serous membrane lining
• provides essential lubrication
• separates parietal and visceral surfaces, allowing sliding without friction or irritation

• excess peritoneal fluid causing abdominal swelling

• double sheets of peritoneal membrane
• suspend portions of the digestive tract within the peritoneal cavity by sheets of serous membrane that connect parietal and visceral peritoneum
• stabilize positions of attached organs
• prevent intestines from being entangled

-provides an access route to and from the digestive tract for passage of blood vessels, nerves, and lymphatic vessels

• fat skin
• stabilizes the position of the stomach
• provides an access route for blood vessels and other structures entering or leaving the liver
• attaches stomach to liver

• helps stabilize the position of the liver, relative to the diaphragm and abdominal wall

• enlarges to form an enormous pouch, called the greater omentum

• extends inferiorly between the body wall and the anterior surface of the small intestine
• hangs like an apron, from the inferior and lateral borders of the stomach

• conforms to shapes of surrounding organs
• provides padding & protection
• insulates to reduce heat loss
• stores lipid energy reserves

• suspends all but the first 25 cm of small intestine
• thick mesenterial sheet
• provides stability, but permits SOME independent movement
• associated with the duodenum and pancreas
• fuses with posterior abdominal wall, locking structures in position

1. mucosa
2. submucosa
3. muscularis externa
4. serosa

• the inner lining of digestive tract
• mucous membrane
• consists of epithelium, moistened by glandular secretions
• lamina propria of areolar tissue

• mucosal epithelium is either simple or stratified depending on the location, function, and stresses

• oral cavity
• pharynx
• esophagus

• for absorption
• stomach
• small intestine
• most of the large intestine
• contains mucous cells

• scattered amongst columnar cells of the digestive tract
• secrete hormones that coordinate the activities of the digestive tract

• appears as longitudinal folds, which disappears as the tract fills
• folding increases the surface area available for absorption

• layer of areolar tissue
• contains:
  1. blood vessels
  2. sensory nerve ending
  3. lymphatic vessels
  4. smooth muscle cells
  5. scattered areas of lymphoid tissue

• narrow sheet of smooth muscle and elastic fibers in lamina propria
• cells are arranged in two concentric layers

• layer of dense irregular connective tissue
• binds the mucosa to the muscularis externa
• has numerous blood and lymphatic vessels
• some regions contains exocrine glands that secrete buffers and enzymes into the lumen of the digestive tract

• aka Meissner plexus
• network of intrinsic nerve fibers and scattered neurons
• contains sensory neurons, parasympathetic ganglionic neurons, and sympathetic postganglionic fibers

• smooth muscles dominates this region
• cells are arranged in circular layer and outer longitudinal layer