Human Digestive System Quiz
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Questions and Answers

What is the primary function of the ileo-cecal valve?

  • To absorb water from chyme
  • To enhance the absorption of vitamins
  • To facilitate the passage of food to the rectum
  • To prevent back flow of chyme from the small intestine (correct)

Which section is the last part of the large intestine?

  • Cecum
  • Rectum
  • Transverse colon
  • Sigmoid colon (correct)

Which vitamins are absorbed in the large intestine?

  • A and C
  • D and E
  • Folate and B12
  • B and K (correct)

What term describes the process that involves strong peristaltic waves occurring in the large intestine?

<p>Mass peristalsis (B)</p> Signup and view all the answers

How long does chyme generally spend in the large intestine before being converted into feces?

<p>7-10 hours (B)</p> Signup and view all the answers

What reflex initiates mass peristalsis in the large intestine?

<p>Gastro-colic reflex (A)</p> Signup and view all the answers

What primarily contributes to the color of feces?

<p>Stercobilin generated from bilirubin breakdown (A)</p> Signup and view all the answers

Which structure controls involuntary defecation?

<p>Internal anal sphincter (C)</p> Signup and view all the answers

Which components are primarily absorbed in the small intestine?

<p>Water, minerals, and water-soluble vitamins (A)</p> Signup and view all the answers

Which type of cell in the small intestine is primarily responsible for nutrient absorption?

<p>Absorptive cells (D)</p> Signup and view all the answers

What role do brush border enzymes play in carbohydrate digestion?

<p>They convert disaccharides into monosaccharides (D)</p> Signup and view all the answers

During the defecation reflex, which bodily function is primarily activated?

<p>Contraction of rectal muscles (D)</p> Signup and view all the answers

What is the primary function of gastric juice in the stomach?

<p>To dissolve food and mix it into chyme (A)</p> Signup and view all the answers

Which cell type in the stomach secretes hydrochloric acid?

<p>Parietal cells (B)</p> Signup and view all the answers

What happens to salivary amylase in the acidic environment of the stomach?

<p>It gets inactivated (A)</p> Signup and view all the answers

Which part of the stomach is directly involved in the passage of chyme into the small intestine?

<p>Pylorus (A)</p> Signup and view all the answers

Which substance is secreted by G cells in the stomach?

<p>Gastrin (D)</p> Signup and view all the answers

What is the 'alkaline tide' associated with in the stomach?

<p>Increase of bicarbonate ions in the circulation (B)</p> Signup and view all the answers

What is the role of pepsin in the stomach?

<p>To digest proteins (C)</p> Signup and view all the answers

What primarily distinguishes the pyloric antrum from the pyloric canal?

<p>Size and function (C)</p> Signup and view all the answers

Which mechanism is responsible for the secretion of hydrogen ions in the stomach?

<p>Active transport via proton pump (A)</p> Signup and view all the answers

How does the stomach ensure that proteins are optimally digested?

<p>By maintaining a low pH with HCl (D)</p> Signup and view all the answers

What is the primary mechanism by which monosaccharides are absorbed in the small intestine?

<p>Facilitated diffusion for fructose and active transport for glucose and galactose (D)</p> Signup and view all the answers

How are dipeptides and tripeptides primarily absorbed in the small intestine?

<p>Mostly through active transport (C)</p> Signup and view all the answers

What role do micelles play in the absorption of lipids?

<p>They encapsulate fatty acids to facilitate diffusion across intestinal cells (B)</p> Signup and view all the answers

What is the intestines' movement speed of chyme as it travels towards the large intestine?

<p>10 cm/sec (A)</p> Signup and view all the answers

What percentage of lipid absorption occurs in the small intestine?

<p>95% (D)</p> Signup and view all the answers

Which type of vitamins can be absorbed alongside fatty acids in the small intestine?

<p>Lipid-soluble vitamins: A, D, E, and K (C)</p> Signup and view all the answers

What mechanism governs the absorption of water in the intestines?

<p>Simple diffusion and osmotic gradients (B)</p> Signup and view all the answers

Which phase of gastric secretion is initiated by the smell and sight of food?

<p>Cephalic phase (C)</p> Signup and view all the answers

What nutrients are broken down by pancreatic lipase during lipid digestion?

<p>Triglycerides into fatty acids and monoglycerides (D)</p> Signup and view all the answers

What role do stretch receptors in the stomach play during the gastric phase?

<p>Ensuring proper motility and acid secretion (C)</p> Signup and view all the answers

What stimulates the production of intestinal juices in the digestive process?

<p>Vasoactive intestinal polypeptide (VIP) (D)</p> Signup and view all the answers

What is the significance of stretching in the small intestine?

<p>It plays a role in the 'segmentation' process (C)</p> Signup and view all the answers

What physiological effect does gastrin have when released into the bloodstream?

<p>Stimulates the release of gastric juices (D)</p> Signup and view all the answers

What is the primary purpose of secretin in the intestinal phase of digestion?

<p>Stopping gastric secretion (C)</p> Signup and view all the answers

How does the body regulate the emptying of the stomach during the intestinal phase?

<p>Through negative feedback mediated by intestinal hormones (B)</p> Signup and view all the answers

Which neurotransmitter is released by the parasympathetic fibers to stimulate gastric secretion during the gastric phase?

<p>Acetylcholine (D)</p> Signup and view all the answers

What happens to the pH of the stomach as partially digested proteins enter, and why is it significant?

<p>It rises, inhibiting gastric secretion (C)</p> Signup and view all the answers

What is one of the main functions of cholecystokinin (CCK) in the digestive process?

<p>Inhibiting stomach emptying (C)</p> Signup and view all the answers

What is the effect of the vagus nerve during the cephalic phase of digestion?

<p>It stimulates secretion of digestive juices (D)</p> Signup and view all the answers

Flashcards

Large Intestine Length

The large intestine is approximately 1.5 meters long.

Ileo-cecal Valve Function

Prevents backflow of chyme from small to large intestine.

Mass Peristalsis

Strong peristaltic wave, starting at distal transverse colon, 3-4 times a day.

Large Intestine Absorption

Absorbs roughly 0.9 liters of water, sodium, chloride, and some water-soluble vitamins.

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Gastrocolic Reflex

Initiates mass peristalsis 3-4 times a day in the large intestine.

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Defecation Reflex

Rectal stretch triggers signals to the spinal cord, causing strong rectal muscle contractions and abdominal muscle tightening.

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Chyme to Feces Transformation

Chyme, in the large intestine, turns to semisolid feces due to water absorption.

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Bacterial Activity in Large Intestine

Bacteria in the large intestine break down remaining proteins, produce vitamins, and contribute to the odor of feces.

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Pepsinogen Activation

Pepsinogen, an inactive enzyme, is activated by contacting either HCl or an already activated pepsin molecule to prevent autodigestion.

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Gastric Lipase

An enzyme produced by the stomach that helps digest lipids.

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Cephalic Phase

The first phase of gastric secretion, stimulated by factors like smell or thinking about food.

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Gastric Phase

The phase of gastric secretion triggered by food entering the stomach; stretching activates production of gastric fluids, which also depend on the pH.

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Gastrin

A hormone released by the stomach that stimulates gastric juice production.

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Intestinal Phase

The phase of gastric secretion inhibition as chyme enters the small intestine; it controls how quickly chyme moves by affecting hormone production.

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Secretin

A hormone secreted by the small intestine that inhibits gastric secretion.

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Cholecystokinin (CCK)

A hormone that inhibits stomach emptying, also important for controlling the movement of chime.

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Chyme

Partially digested food mixture in the stomach.

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Peristalsis

The wave-like muscle contractions that move food through the digestive tract

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Dipeptidase Function

This enzyme breaks down dipeptides (two amino acids linked together) into individual amino acids, ready for absorption.

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Lipid Digestion in Small Intestine

Bile salts emulsify lipids into tiny particles, allowing pancreatic lipase to break down triglycerides into fatty acids and monoglycerides.

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What are Micelles?

Micelles are small, spherical structures formed by fatty acids and bile salts. They aid in lipid absorption.

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How are Monosaccharides Absorbed?

Glucose and galactose are actively transported, while fructose uses facilitated diffusion, all to enter the bloodstream.

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Amino Acid Absorption

Amino acids, dipeptides, and tripeptides are absorbed by active transport in the small intestine, primarily in the duodenum and jejunum.

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Lipid Absorption Mechanism

Fatty acids, glycerol, and monoglycerides are absorbed through simple diffusion, mostly in the small intestine.

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Water Absorption in the Intestine

Approximately 10 liters of liquid enter the intestine daily, with about 95% absorbed, primarily in the small intestine.

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Stomach Capacity

The stomach can hold approximately 1.5 to 2 liters of food.

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Stomach Layers

The stomach has three layers of muscle within its walls.

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What are Enteric Reflexes?

These are reflexes controlled by the nervous system within the intestinal wall. They play a crucial role in intestinal secretion and motility.

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VIP and Intestinal Juice

Vasoactive intestinal polypeptide (VIP) stimulates the production of intestinal juices, aiding digestion.

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Stomach Regions

The stomach has four main areas: cardia, fundus, body, and pylorus.

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Stomach Curvatures

Due to its shape, the stomach has a greater and lesser curvature.

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Chyme Movement: Speed and Time

Chyme travels through the digestive system at approximately 10 cm/second, taking about 4 hours to reach the large intestine.

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Stomach Mucosa

The stomach lining has folds called rugae.

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Surface Mucous Cells

These cells in the stomach secrete mucus to protect the lining from acid.

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Parietal Cells

Secretes HCl acid and intrinsic factor for vitamin B12 absorption.

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Chief Cells

These cells secrete pepsinogen and gastric lipase, which break down proteins and fats.

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G Cells

Secrete gastrin, a hormone that stimulates gastric juice production.

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Mixing Waves

The stomach uses mixing waves to churn and mix food with gastric juice.

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Small Intestine Length

The small intestine is approximately 6 meters (19-20 feet) long, roughly four times the length of a person's height.

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Small Intestine Sections

The small intestine is divided into three sections: the duodenum (shortest), the jejunum (most vascular), and the ileum (longest).

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Small Intestine Absorption

The small intestine is the primary site of nutrient absorption, absorbing almost all nutrients from the chyme. Only water, minerals, and water-soluble vitamins are absorbed in the large intestine.

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Villi and Microvilli

The small intestine's inner lining has numerous tiny projections called villi, further covered with microscopic projections called microvilli, which greatly increase the surface area for absorption.

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Small Intestine Motility

The small intestine uses segmentation, a unique movement, to thoroughly mix intestinal juices with chyme, enhancing digestion and absorption.

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Study Notes

Stomach

  • The stomach is a portion of the digestive tract, capable of storing 1.5-2 liters of food.
  • It has three layers of muscle within its walls.
  • Four major parts of the stomach are: Cardia, Fundus, Body, and Pylorus (including Pyloric Antrum, Pyloric Canal, and Pyloric Sphincter).
  • The stomach's curved shape is characterized by the greater and lesser curvatures.
  • The stomach lining (mucosa) is folded into rugae.

Stomach Glands

  • Surface mucous cells secrete mucus.
  • Mucous neck cells secrete mucus.
  • Parietal cells secrete hydrochloric acid and intrinsic factor (for vitamin B12).
  • Chief cells secrete pepsinogen and gastric lipase.
  • G cells secrete gastrin.

Stomach Function

  • Mixing waves, rather than peristaltic waves, mix food with gastric juice, converting it to a liquid called chyme.
  • Stomach acid inactivates salivary amylase but activates lingual lipase, which begins the breakdown of triglycerides.
  • A proton pump, which is an H+/K+ pump, utilizes ATP to move hydrogen ions into the stomach lumen, activating pepsinogen into pepsin.
  • Hydrochloric acid (HCl) created helps eliminate microorganisms, denatures proteins, and stimulates hormone production which facilitates bile and pancreatic juice production

Regulation of Gastric Secretion and Motility

  • Cephalic, gastric, and intestinal phases are overlapping stages of digestion, influenced by various neural and hormonal factors.
  • Cephalic phase: Initiated by stimuli other than food ingestion, like smell, sight, or thoughts of food. This stimulates medulla oblongata, initiating the secretion of pepsinogen, mucus, and HCl. Gastrin hormone also is released to bloodstream.
  • Gastric phase: Initiated by stretching and increased pH inside the stomach. Stretch and pH receptors initiate continuous gastric secretion as long as food is present. Peristalsis pushes chyme into the duodenum.
  • Intestinal phase: When chyme enters the small intestine, intestinal reflexes inhibit gastric secretion and slow stomach emptying to prevent overwhelming the duodenum with chyme. Chyme causes secretion of secretin and cholecystokinin (CCK) which inhibits further gastric emptying.

Small Intestine

  • The small intestine is a long, highly absorptive section of the gastrointestinal tract (approximately 3-3.5 meters).
  • It has three sections: duodenum, jejunum, and ileum.
  • Inner lining (mucosa) features circular folds, villi, and microvilli to maximize absorption surface area.
  • It's connected to the posterior abdominal wall by the mesentery.
  • The small intestine creates intestinal juice, essential to process chyme and contains different cell types including: Absorbent, goblet, enteroendocrine, and paneth cells.

Chemical digestion in large intestine

  • Bacteria in the large intestine break down remaining proteins, resulting in amino acids.
  • Bilirubin breakdown yields stercobilin (feces color).
  • B and K vitamins are absorbed.
  • Approximately 0.9 liters of fluid are absorbed in the large intestine, along with sodium, chloride, and some water-soluble vitamins.

Defecation Reflex

  • The rectum (ampulla) is a temporary storage site for digestive waste products.
  • Stretch receptors in the rectum initiate a reflex that enforces large intestine emptying by stimulating parasympathetic fibers.
  • Voluntary sphincter control allows the passage of feces.

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Digestive System Handout - Part 2 PDF

Description

Test your knowledge on the functions and anatomy of the large intestine in the human digestive system. This quiz covers key aspects such as the ileo-cecal valve, nutrient absorption, and the processes involved in defecation. Challenge yourself and see how much you know about this vital organ.

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