Human Digestive System Quiz

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Questions and Answers

What is the primary function of saliva in digestion?

Facilitating the absorption of proteins

Breaking down fats into fatty acids

Enhancing bone mineralization

Regulating bacteria population (correct)

Which of the following substances is NOT found in gastric secretions?

Pepsinogen

Hydrochloric acid

Intrinsic factor

Amylase (correct)

What role does intrinsic factor play in digestion?

Stimulates salivary amylase

Neutralizes gastric acids

Facilitates the absorption of vitamin B12 (correct)

Activates pepsinogen to pepsin

Which type of cell in the gastric glands secretes hydrochloric acid?

Parietal cells Signup and view all the answers

What is the composition of saliva primarily aimed at?

Moistening food for swallowing Signup and view all the answers

Which gland secretes the hormone gastrin?

Pyloric gland Signup and view all the answers

What is the primary component of saliva that has minimal digestive enzyme activity?

Salivary amylase Signup and view all the answers

Which of these is NOT a primary function of saliva?

Increasing food temperature Signup and view all the answers

What is the primary function of the gastrointestinal system?

To provide nutrients and electrolytes Signup and view all the answers

Which of the following structures is part of the gastrointestinal tract?

Esophagus Signup and view all the answers

What initiates carbohydrate digestion in the digestive system?

Salivary amylase Signup and view all the answers

What is the primary role of the muscular wall in the stomach?

Producing digestive movements Signup and view all the answers

Where does the majority of nutrient absorption occur in the gastrointestinal system?

Small intestine Signup and view all the answers

Which component is secreted by gastric pits in the stomach?

Pepsinogen Signup and view all the answers

What is the primary passage for food after chewing?

Pharynx Signup and view all the answers

Which organ is NOT classified as an accessory glandular organ?

Stomach Signup and view all the answers

Which layer of smooth muscle decreases the diameter of the lumen in the gastrointestinal tract?

Thick inner circumferential layer Signup and view all the answers

What is the primary function of myenteric plexus in the gastrointestinal system?

Regulate GI tract functions Signup and view all the answers

Which of the following movements is characterized by pushing contents forward through the digestive tract?

Peristaltic contraction Signup and view all the answers

What is the role of serosa in the gastrointestinal tract?

Lubricate and prevent friction with surrounding organs Signup and view all the answers

Which type of contraction facilitates both digestion and absorption in the gastrointestinal tract?

Phasic contractions Signup and view all the answers

What kind of muscle is primarily found in the gastrointestinal tract?

Smooth muscle Signup and view all the answers

Ingestion in the digestive system is defined as which of the following processes?

Process of eating Signup and view all the answers

Which layer of the gastrointestinal tract is responsible for the secretion of digestive juices?

Mucosa Signup and view all the answers

What characterizes phasic contractions in the gastrointestinal tract?

They decrease transit time with increased peristalsis. Signup and view all the answers

How do interstitial cells of Cajal (ICC) function in the gastrointestinal motility?

They serve as the pacemakers and initiate depolarization waves. Signup and view all the answers

What is the primary function of tonic contractions in the gastrointestinal tract?

Increase transit time through retention. Signup and view all the answers

Which of the following statements about slow waves in the gastrointestinal tract is true?

They develop from specialized smooth muscle cells. Signup and view all the answers

What happens during the mixing in the antrum of the stomach?

Thick muscle contractions occur along with powerful mixing. Signup and view all the answers

What is the primary function of bile salts in digestion?

To convert large fat globules into smaller pieces Signup and view all the answers

What is the main requirement for the secretion of digestive juices in the gastrointestinal tract?

Neural or hormonal stimulation. Signup and view all the answers

What characterizes peristaltic waves in the GI tract?

They are responsible for the propulsion of contents through the GI tract. Signup and view all the answers

How do monoglycerides and fatty acids enter absorptive cells?

By simple diffusion or forming micelles Signup and view all the answers

What effect does the enteric nervous system (ENS) have on slow waves in the GI tract?

It modulates the amplitude and frequency of slow waves. Signup and view all the answers

What triggers the secretion of bile into the duodenum?

Presence of fats in the duodenal lumen Signup and view all the answers

What is the role of the sphincter of Oddi in digestion?

It controls the flow of bile into the small intestine Signup and view all the answers

Which of the following describes mechanical digestion?

Physical processes like chewing and churning Signup and view all the answers

What substances are secreted by the small intestine to aid in digestion?

Water, salt, and mucus Signup and view all the answers

What is the primary function of the enzymes present in the small intestine?

To aid in the digestion of food Signup and view all the answers

What happens to bile when little or no food is present in the intestinal lumen?

It is diverted into the gallbladder Signup and view all the answers

Which structure in the gastrointestinal system is responsible for nutrient absorption and digestion?

Villi Signup and view all the answers

What is the definition of digestion?

The breakdown of food to its chemical components Signup and view all the answers

What are the protective roles of the mucosa in the gastrointestinal tract?

Providing a barrier against pathogens and absorption Signup and view all the answers

What is one potential consequence of dysbiosis in the large intestine?

Development of obesity Signup and view all the answers

Which layer of the gastrointestinal tract contains the submucosal plexus?

Submucosa Signup and view all the answers

What role do microvilli play in the small intestine?

They increase the surface area for absorption Signup and view all the answers

What primarily gets absorbed in the large intestine?

Water and some electrolytes Signup and view all the answers

What dietary component can ease movement through the large intestine and decrease constipation risk?

Fiber-rich foods Signup and view all the answers

Study Notes

Physiology (0603302) Ch. 6 Gastrointestinal System

The gastrointestinal (GI) system is responsible for providing nutrients and electrolytes from the external environment to maintain homeostasis.
The digestive system comprises two main parts: the GI tract and accessory glands.
The GI tract includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.
Accessory glands include the salivary glands, liver, gallbladder, and pancreas.
The mouth contains muscles for mechanical digestion. Salivary glands produce saliva essential for lubrication, food degradation, and carbohydrate digestion, initiating with salivary amylase.
Food passes through the pharynx, a passageway for both food and air.
The esophagus carries food to the stomach by peristaltic contractions.
The stomach contains a special lining to secrete digestive juices (pepsinogen, HCl) for protein digestion. Gastric pits originate digestive juices/enzymes.
The stomach's muscular wall mechanically mixes food with digestive juices, and food passes through the pylorus sphincter to the small intestine.
The small intestine, with enzymes from the pancreas and small intestine, further digests food; it contains villi cells that increase surface area for absorption. The villi and microvilli are lined with enterocytes.
The large intestine absorbs water and electrolytes; beneficial bacteria produce vitamin K and some lipid molecules. Some diseases like diabetes and obesity may result from problems with gut bacteria.
The large intestine facilitates the formation of feces. A high-fiber diet facilitates movement through the large intestine, potentially decreasing constipation risk.
The GI system has four primary layers: Mucosa (innermost layer of epithelial cells, with protective, secretion, and absorption roles); Submucosa (beneath the mucosa, consisting of connective tissue, neurons, and blood vessels with GI tract distensibility and elasticity); Muscle (two layers of smooth muscle—inner circumferential and outer longitudinal layers); and Serosa (outermost layer of connective tissue).
Motility involves phasic contractions (peristalsis and segmentation for rapid transport of food and nutrients, and tonic contractions (sphincter) for regulated and prolonged retention).

Processing of Food by the DS

Ingestion is the process of eating.
Digestion: Chemical and mechanical breakdown of food into absorbable units.
Mechanical digestion prepares food for chemical digestion (chewing, mixing with saliva). Chemical digestion is achieved by enzymes in digestive juices.

GIT Secretion

Digestive secretions are essential for digestion and absorption.
The volume of digestive secretions is high compared to ingested fluids.
Digestive fluid synthesis & secretion are controlled by endocrine, paracrine, and neural regulation.
Saliva from the salivary glands (parotid, submandibular, and lingual glands) in the mouth is a mixed secretion, with proteins and water (parotid), and both mucus and enzyme amylase (submandibular and lingual). Saliva's functions include moistening for swallowing, neutralizing acids and bacteria, and initiating some digestion (minimal salivary amylase and lingual lipase).
The stomach secretes HCL, Pepsinogen, mucus, and intrinsic factor. HCl activates Pepsinogen → Pepsin; mucus forms a protective barrier. Intrinsic factor combines with Vitamin B12 for absorption.
Pancreatic secretions include proteases (cleave peptides), nucleases (hydrolyze DNA/RNA), elastases (digest collagen), phospholipases (split phospholipids), lipases (break triglycerides into glycerol +fatty acids), and amylase (starch to maltose + glucose). Pancreatic duct cells secrete bicarbonate, creating a neutral environment for pancreatic enzyme function.

Digestion: Overview (Table 14-5)

Carbohydrate digestion begins in the mouth with salivary amylase. Disaccharidases in the small intestine complete carbohydrate breakdown to monosaccharides (particularly glucose).
Protein digestion starts in the stomach with pepsin. Pancreatic proteases, aminopeptidases, and carboxypeptidases further break down proteins into peptides and then amino acids.
Fat digestion involves emulsification by bile salts—forming micelles that increase lipase enzyme access to triglycerides—breaking down to monoglycerides and fatty acids, which are then absorbed by simple diffusion or by forming micelles.

Absorption

The passage of digested food particles into blood and lymphatic systems.
Most absorption happens in the small intestine.

Defecation

Elimination of indigestible food substances.

Regulation of Gastrointestinal Tract Functions

Intrinsic (in the GI wall) and extrinsic (external to GI wall) control systems regulate GI tract functions.
Intrinsic control involves the enteric nervous system (ENS) and endocrine secretions (e.g., secretin, gastrin, CCK, GIP, and motilin), which respond to various stimuli within the digestive tract.
Extrinsic control includes nerves (vagus and splanchnic) and hormones (e.g., aldosterone) that regulate GI function.

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Description

Test your knowledge on the human digestive system with this quiz. It covers the roles of saliva, gastric secretions, and various components involved in digestion. Understand the functions and anatomy of the gastrointestinal tract effectively.