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Questions and Answers
What is the primary function of teeth in the mechanical digestion process?
What is the primary function of teeth in the mechanical digestion process?
- To churn and grind food (correct)
- To propel food through the digestive tract
- To absorb nutrients
- To chemically break down food
What role do gastric juices play in the stomach?
What role do gastric juices play in the stomach?
- They break down food chemically (correct)
- They propel food through the digestive tract
- They mechanically grind food
- They absorb nutrients
Which of the following best describes segmentation in the small intestine?
Which of the following best describes segmentation in the small intestine?
- Mixing of food with digestive juices (correct)
- A voluntary act of swallowing
- Relaxation of muscles ahead of the bolus
- Muscle contractions that push food down
What is the term for the involuntary muscle action that propels food through the digestive tract?
What is the term for the involuntary muscle action that propels food through the digestive tract?
Which statement describes the contraction and relaxation of muscles during peristalsis?
Which statement describes the contraction and relaxation of muscles during peristalsis?
Which site does NOT participate in mechanical digestion?
Which site does NOT participate in mechanical digestion?
How does saliva contribute to mechanical digestion?
How does saliva contribute to mechanical digestion?
What process occurs in the stomach to enhance mechanical digestion?
What process occurs in the stomach to enhance mechanical digestion?
What process involves the involuntary movement of food through the digestive tract?
What process involves the involuntary movement of food through the digestive tract?
Which term describes the mechanical breakdown of food into smaller fragments?
Which term describes the mechanical breakdown of food into smaller fragments?
What is the primary function of gastric juices in digestion?
What is the primary function of gastric juices in digestion?
Which process describes the absorption of digested nutrients into the blood or lymph?
Which process describes the absorption of digested nutrients into the blood or lymph?
What is the role of muscle contractions during digestion in the alimentary canal?
What is the role of muscle contractions during digestion in the alimentary canal?
Which of the following processes occurs after food is broken down into smaller particles?
Which of the following processes occurs after food is broken down into smaller particles?
Which action involves the voluntary movement of food through the throat?
Which action involves the voluntary movement of food through the throat?
The elimination of waste from the body is known as what?
The elimination of waste from the body is known as what?
What is the primary function of pepsin in the digestive system?
What is the primary function of pepsin in the digestive system?
Which structure in the small intestine significantly increases the surface area for nutrient absorption?
Which structure in the small intestine significantly increases the surface area for nutrient absorption?
How do circular folds in the small intestine aid in digestion?
How do circular folds in the small intestine aid in digestion?
What role do tight junctions in the intestinal epithelium serve?
What role do tight junctions in the intestinal epithelium serve?
What is the composition of the core found in the villi of the small intestine?
What is the composition of the core found in the villi of the small intestine?
Which of the following is a result of mechanical digestion in the small intestine?
Which of the following is a result of mechanical digestion in the small intestine?
What is the pH range of intestinal juice secreted by crypts in the small intestine?
What is the pH range of intestinal juice secreted by crypts in the small intestine?
What is the purpose of the brush border formed by microvilli in the small intestine?
What is the purpose of the brush border formed by microvilli in the small intestine?
What activates pepsinogen to become active pepsin in the stomach?
What activates pepsinogen to become active pepsin in the stomach?
Which of the following accurately describes the structure of the small intestine?
Which of the following accurately describes the structure of the small intestine?
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Study Notes
Propulsion of Food
- Food moves through the digestive tract via two processes: swallowing (voluntary) and peristalsis (involuntary).
- Peristalsis involves alternating contractions and relaxations of circular and longitudinal muscles.
- Circular muscles contract behind the bolus, while longitudinal muscles ahead of the bolus relax, pushing the bolus down the tract.
Mechanical Digestion
- Mechanical digestion occurs at three key sites:
- Mouth: Teeth grind, churn, and mix food with saliva.
- Stomach: Food is churned and mixed with gastric juices.
- Small Intestine: Segmentation occurs, further mixing food.
Chemical Digestion
- Breaks down complex molecules into smaller chemical units using enzymes.
- Pepsinogen is activated to pepsin in the stomach, aiding in protein digestion.
Nutrient Absorption
- Digested products pass from the digestive tract into the blood or lymph via passive or active transport.
- The small intestine's structure maximizes nutrient absorption efficiency.
Anatomy of the Small Intestine
- The small intestine is long and features circular folds, villi, and microvilli to increase surface area for absorption.
- Circular folds (plicae circulares): Deep folds in the mucosa and submucosa slow down chyme movement for better absorption time.
- Villi: Small projections made of absorptive epithelial cells connected by tight junctions, containing a capillary bed and lacteals for nutrient transport.
- Microvilli: Dense projections on epithelial cells, forming a 'brush border' that hosts enzymes for carbohydrate, protein, and nucleic acid digestion.
Intestinal Glands
- Located in the pits between villi, known as intestinal crypts, and secrete intestinal juice (pH 7.4).
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