GIT: Composition, Characteristics, Functions, Regulations

Question 1

What is the gastrointestinal tract (GIT)?

Answer 1

The gastrointestinal tract (GIT) is a long hollow tube extending from the mouth to the anus, responsible for digestion and absorption of nutrients.

Question 2

What are the primary functions of the GIT?

Answer 2

The primary functions of the GIT include digestion of food, absorption of nutrients, and elimination of waste.

Question 3

Describe the layers of the GIT wall.

Answer 3

The layers of the GIT wall include the mucosa, submucosa, muscularis externa, and serosa (or adventitia).

Question 4

What is the mucosa layer of the GIT composed of?

Answer 4

The mucosa layer of the GIT is composed of epithelium, lamina propria, and muscularis mucosae.

Question 5

What are the functions of the mucosa layer?

Answer 5

The mucosa layer functions in secretion, absorption, and protection of the GIT.

Question 6

What is the submucosa layer of the GIT composed of?

Answer 6

The submucosa layer of the GIT is composed of connective tissue, blood vessels, and nerves.

Question 7

What structures are found in the submucosa layer?

Answer 7

Structures found in the submucosa layer include blood vessels, lymphatics, and submucosal glands.

Question 8

What is the function of the submucosa layer?

Answer 8

The submucosa layer provides support and supplies nutrients to the mucosa layer.

Question 9

Describe the muscularis externa layer of the GIT.

Answer 9

The muscularis externa layer of the GIT consists of smooth muscle responsible for peristalsis and segmentation.

Question 10

What types of muscle are present in the muscularis externa?

Answer 10

The muscularis externa contains inner circular and outer longitudinal layers of smooth muscle.

Question 11

What is the function of the muscularis externa?

Answer 11

The function of the muscularis externa is to propel food along the GIT through peristalsis and mix food through segmentation.

Question 12

What is the serosa (or adventitia) layer of the GIT?

Answer 12

The serosa (or adventitia) layer of the GIT is the outermost layer that provides protection and support to the GIT.

Question 13

Describe the structure and function of the mouth in digestion.

Answer 13

The mouth is the entry point for food digestion, where mechanical breakdown and initial chemical digestion occur.

Question 14

What are the functions of saliva in the mouth?

Answer 14

Saliva in the mouth contains enzymes that begin the digestion of carbohydrates and lubricate food for swallowing.

Question 15

Explain the process of mastication.

Answer 15

Mastication is the process of chewing food to break it down into smaller particles, facilitating swallowing and digestion.

Question 16

How does saliva aid in swallowing?

Answer 16

Saliva aids in swallowing by moistening and lubricating food, forming a bolus that can be easily swallowed.

Question 17

Describe the structure and function of the esophagus.

Answer 17

The esophagus is a muscular tube that transports food from the mouth to the stomach through peristalsis.

Question 18

What is peristalsis, and how does it occur in the esophagus?

Answer 18

Peristalsis in the esophagus is coordinated by smooth muscle contractions that propel food downward toward the stomach.

Question 19

What prevents reflux of stomach contents into the esophagus?

Answer 19

The lower esophageal sphincter prevents reflux of stomach contents into the esophagus by closing tightly after food passes through.

Question 20

Describe the structure and function of the stomach.

Answer 20

The stomach is a muscular organ that stores, mixes, and digests food, producing gastric juices for chemical digestion.

Question 21

What are the main secretions of the stomach?

Answer 21

The main secretions of the stomach include hydrochloric acid, pepsinogen, intrinsic factor, and mucus.

Question 22

Explain the process of gastric emptying.

Answer 22

Gastric emptying is the process by which food is emptied from the stomach into the duodenum for further digestion and absorption.

Question 23

What are the functions of gastric acid in the stomach?

Answer 23

Gastric acid in the stomach helps in protein digestion, creates an acidic environment for enzyme activity, and kills bacteria.

Question 24

Describe the structure and function of the small intestine.

Answer 24

The small intestine is the primary site for digestion and absorption of nutrients, consisting of the duodenum, jejunum, and ileum.

Question 25

What are the three segments of the small intestine?

Answer 25

The three segments of the small intestine are the duodenum, jejunum, and ileum.

Question 26

What is the function of the duodenum in digestion?

Answer 26

The duodenum receives chyme from the stomach and plays a key role in digestion through mixing and enzyme secretion.

Question 27

How does the jejunum contribute to nutrient absorption?

Answer 27

The jejunum is the primary site for nutrient absorption, especially carbohydrates, proteins, and lipids.

Question 28

What is the function of the ileum in the small intestine?

Answer 28

The ileum completes nutrient absorption and plays a role in the absorption of bile salts and vitamin B12.

Question 29

Describe the structure and function of the large intestine.

Answer 29

The large intestine absorbs water and electrolytes, forms and stores feces, and houses gut microbiota.

Question 30

What are the main functions of the large intestine?

Answer 30

The main functions of the large intestine include water absorption, formation of feces, and elimination of waste.

Question 31

Explain the process of segmentation in the small intestine.

Answer 31

Segmentation in the small intestine involves alternating contractions and relaxations of circular smooth muscle, mixing chyme with digestive juices.

Question 32

What role does segmentation play in digestion and absorption?

Answer 32

Segmentation facilitates digestion and absorption by mixing chyme with digestive enzymes and bringing it into contact with the intestinal mucosa.

Question 33

Describe the process of peristalsis in the small intestine.

Answer 33

Peristalsis in the small intestine involves coordinated contractions of circular and longitudinal smooth muscle, propelling chyme along the GIT.

Question 34

How does peristalsis facilitate movement of food in the GIT?

Answer 34

Peristalsis facilitates movement of food along the GIT by propelling it forward through rhythmic contractions.

Question 35

What are the regulatory mechanisms of GIT motility?

Answer 35

GIT motility is regulated by the enteric nervous system, autonomic nervous system, and hormonal factors.

Question 36

Describe the role of the enteric nervous system in GIT regulation.

Answer 36

The enteric nervous system coordinates GIT motility locally within the GIT, controlling processes like peristalsis and secretion.

Question 37

What is the role of the autonomic nervous system in GIT regulation?

Answer 37

The autonomic nervous system, including the sympathetic and parasympathetic divisions, regulates GIT motility and secretion.

Question 38

Explain the hormonal regulation of GIT functions.

Answer 38

Hormonal regulation of GIT functions involves hormones such as gastrin, secretin, cholecystokinin (CCK), and gastric inhibitory peptide (GIP).

Question 39

What hormones are involved in GIT regulation, and what are their functions?

Answer 39

Gastrin stimulates gastric acid secretion and promotes gastric motility in response to food ingestion.

Question 40

Describe the cephalic phase of digestion.

Answer 40

Secretin stimulates pancreatic bicarbonate secretion in response to acidic chyme entering the duodenum.

Question 41

What triggers the cephalic phase of digestion?

Answer 41

Cholecystokinin (CCK) stimulates pancreatic enzyme secretion and gallbladder contraction in response to fatty acids and amino acids in the duodenum.

Question 42

Explain the gastric phase of digestion.

Answer 42

Gastric inhibitory peptide (GIP) inhibits gastric acid secretion and stimulates insulin release in response to nutrients in the duodenum.

Question 43

What stimulates the gastric phase of digestion?

Answer 43

The cephalic phase of digestion is initiated by the sight, smell, taste, or thought of food, leading to the secretion of gastric juices.

Question 44

Describe the intestinal phase of digestion.

Answer 44

The gastric phase of digestion occurs when food enters the stomach, stimulating gastric acid and enzyme secretion.

Question 45

What triggers the intestinal phase of digestion?

Answer 45

The intestinal phase of digestion involves the inhibition of gastric emptying and acid secretion and the stimulation of pancreatic secretion.

Question 46

How is the intestinal phase of digestion regulated?

Answer 46

The intestinal phase of digestion is regulated by hormones such as secretin, CCK, and GIP, as well as neural reflexes.

Question 47

Explain the role of secretin in GIT regulation.

Answer 47

Secretin is released from the duodenum in response to acidic chyme, stimulating pancreatic bicarbonate secretion to neutralize acidity.

Question 48

Describe the functions of cholecystokinin (CCK) in GIT regulation.

Answer 48

Cholecystokinin (CCK) is released from the duodenum in response to fatty acids and amino acids, stimulating pancreatic enzyme secretion and gallbladder contraction.

Question 49

What is the role of gastric inhibitory peptide (GIP) in GIT regulation?

Answer 49

Gastric inhibitory peptide (GIP) is released from the duodenum in response to nutrients, inhibiting gastric acid secretion and stimulating insulin release.

Question 50

How does motilin contribute to GIT motility?

Answer 50

Motilin is released from the duodenum during fasting, stimulating migrating motor complexes (MMCs) to clear residual food from the stomach and small intestine.