Bio 169 Exam 3 (Answered) Questions and
Correct Answers, With Complete Verified
Solutions, 2024/2025.
Gallbladder
To store and concentrate bile. 40-70 ml of bile is stored. Cholecystokinin stimulates contractions to
release bile.
Pancreas
Composed of endocrine and exocrine tissues. The endocrine consists of islets of langerhans and the
exocrine consists of acinar cells within acini.
Salivary glands
Lingual glands, palatine glands, buccal glands, and labia glands
Large intestine
Slight segmental mixing occurs. Mass movements propel feces toward the anus. Mucus and bicarbonate
ions protect against acids produced by bacteria. The proximal half of the colon absorbs salts, water, and
vitamins produced by bacteria. The distal half of the colon holds feces.
small intestine
Secretes: bicarbonate ions from the pancreas and bile from the liver neautralize stomach acid to form a
pH environment. Bile contains bilirubin and excess cholesterol that will be eliminated by feces. Enzymes
from the pancreas and the lining of the small intestine complete the breakdown of food molecules. Bile
salts from the liver emulsify lipids for lipid digestion. Absorption: the circular folds, villi, and microvilli
increase surface area. Nutrients are actively or passively absorbed.
Stomach
Mixing waves churn materials into chyme. Rugae allow the stomach to expand and store food. Peristaltic
waves move the chyme into the small intestine. Secretes hydrochloric acid, the acid kills microorganisms
and activates the precursor of the proteolytic enzyme pepsin. Gastric lipase and intrinsic factor are
secreted. Protein digestion begins as a result of hydrochloric acid and pepsin. Absorption takes place
with water, aspirin, and alcohol.
Pharynx
Propulsion and mixing: the involuntary phase of swallowing moves the bolus from the oral cavity to the
esophagus. Materials are prevented from entering the nasal cavity by the soft palate and kept out of the
lower respiratory tract by the epiglottis and vestibular folds. Secretion: mucus provides lubrication.
Oral cavity
, Ingestion, mastication, propulsion and mixing, secretion, digestion, and absorption
Epiglottis
Esophagus voluntary control
Esophagus involuntary control
Anus
Propulsion
The movement of food from one end of the digestive tract to the other. Takes 24-36 hours. It begins with
swallowing, following peristalsis, and mass movements.
Segmentation (segmental contractions)
Mix food particles with digestive secretions in the small intestine.
Peristalsis
Propels material through the digestive tract. Muscular contractions/waves is a wave of relaxation of the
circular muscles behind the bolus. Each wave travels the esophagus in about 10 secs.
Mass movements
Contractions that move material in the distal parts of the large intestine to the anus.
Layers of stomach in order
Enteric plexus
Controlling secretion and movement
myenteric plexus
Between the two smooth muscle layers, controls the motility of the intestinal tract.
Layers of intestinal wall in order
Oblique, circular, longitudinal (top to bottom)
Vagus nerve
parietal peritoneum
the outer layer of the peritoneum that lines the interior of the abdominal wall
Greater omentum
The mesentery extending as a fold (apron) from the greater curvature and then to the transverse colon.
Lesser omentum
(Membrane that encloses the bowels) peritoneal fold passing from the liver to the lesser curvature of
the stomach and to the upper border of the duodenum for a distance of 2 cm. beyond the pylorus.
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