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MCAT - Biology > Chapter 9 - The Digestive System > Flashcards

Chapter 9 - The Digestive System Flashcards

1
Q

What is the function of Mechanical Digestion?

A

Mechanical digestion, such as chewing, physically breaks down food into smaller pieces.

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2
Q

What does Intracellular Digestion involve?

A

The oxidation of glucose and fatty acids to make energy.

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3
Q

Where does Extracellular Digestion occur?

A

In the lumen of the alimentary canal.

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4
Q

What is the function of Chemical Digestion?

A

Chemical digestion involves hydrolysis of bonds and breakdown of food into smaller biomolecules.

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5
Q

What is the 7 stem pathway of Digestion?

A
  1. Oral cavity
  2. Pharynx
  3. Esophagus
  4. Stomach
  5. Small intestine
  6. Large intestine
  7. Rectum
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6
Q

What are the 4 accessory organs of digestion?

A
  1. Salivary glands
  2. Pancreas
  3. Liver
  4. Gallbladder
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7
Q

What role does the Enertic Nervous System play in digestion?

A

The Enertic NS is in the wall of the alimentary canal and controls peristalsis. Its activity is unregulated by the parasympathetic nervous system.

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8
Q

What is the role of the Parasympathetic Nervous System in digestion?

A

Innervates/increases secretions of all glands in the body (except sweat glands).

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9
Q

What is the role of the Sympathetic Nervous System in digestion?

A

Slows peristalsis.

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10
Q

What hormones promote thirst?

A

Antidiuretic hormone (ADH or Vasopressin) and Aldosterone.

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11
Q

What hormones promote hunger?

A

Glucagon and Ghrelin

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12
Q

What hormones promote satiety?

A

Leptin and Cholecystokinin

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13
Q

In the oral cavity, what starts the mechanical digestion of food?

A

Mastication

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14
Q

In the small intestine and mouth, what starts the chemical digestion of food?

A

Salivary Amylase and Lipase

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15
Q

What is food formed into before it is swallowed?

A

Bolus

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16
Q

What structures are connected via the Pharynx?

A

The pharynx connects the mouth and posterior nasal cavity to the esophagus.

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17
Q

How does the esophagus propel food into the stomach?

A

Via peristalsis; food enters the stomach through the lower esophageal (cardiac) sphincter

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18
Q

How do Salivary Amylase and Pancreatic Amylase differ?

A

Salivary amylase (active in the mouth) has a higher specificity for rapidly-soluble starches, while Pancreatic amylase (active in small intestine) has a higher specificity for less soluble, more non polar starches.

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19
Q

What are the four parts of the stomach?

A
  1. Fundus
  2. Body
  3. Antrum
  4. Pylorus

*the stomach has a lesser and greater curvature and is thrown into folds called rugae.

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20
Q

What four secretory cells line the stomach?

A
  1. Mucous cells
  2. Chief cells
  3. Parietal cells
  4. G-cells
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21
Q

What are the major secretions and functions of Mucous Cells?

A

Secretes mucus and protects lining of the stomach while increasing pH (bicarbonate)

22
Q

What are the major secretions and functions of Chief Cells?

A

Secretes Pepsinogen and digests proteins. Activated by H+.

23
Q

What are the major secretions and functions of Parietal Cells?

A

Secretes HCl and intrinsic factor; HCl decreases pH, kills microbes, carries out some chemical digestion; intrinsic factor absorbs vitamin B12

24
Q

What are the major secretions and functions of G-Cells?

A

Secretes Gastrin; increases HCl production and increases gastric mobility.

25
Q

What are food particles called after chemical and mechanical digestion in the stomach?

A

Chyme

26
Q

How does food pass through the Duodenum?

A

Through the Pyloric Sphincter

27
Q

What is the Duodenum?

A

The first part of the small intestine; is primarily involved in chemical digestion.

28
Q

What are Disaccharides?

A

Brush-border enzymes that break down maltose, isomaltose, lactose, and sucrose into monosaccharides.

29
Q

What are the two Brush-border peptides?

A

Aminopeptidase and Dipeptidases

30
Q

Is Sucrase an enzyme or a hormone? What are its functions?

A

A brush-border enzyme; breaks down sucrose into monosaccharides

31
Q

Is Secretin an enzyme or a hormone? What are its functions?

A

A hormone; it increases pancreatic secretions, especially bicarbonate; reduces HCl secretion; and decreases motility

32
Q

Is Dipeptidase an enzyme or a hormone? What are its functions?

A

A brush-border enzyme; breaks down dipeptides into free amino acids.

33
Q

Is Cholecystokinin an enzyme or a hormone? What are its functions?

A

A hormone; recruits secretions from gallbladder and pancreas; promotes satiety.

34
Q

Is Enteropeptidase an enzyme or a hormone? What are its functions?

A

An enzyme; activates trypsinogen, which initiates an activation cascade.

35
Q

What do Acinar cells in the pancreas do?

A

Produce pancreatic juices that contain bicarbonate, pancreatic amylase, pancreatic peptidases (trypsinogen, chymotrypsinogen, carboxypeptidases A and B) and pancreatic lipase.

36
Q

Where is Bile synthesized, stored and where does it carry out its function?

A

Bile is synthesized in the liver, stored in the gallbladder, and serves its function in the duodenum.

37
Q

What are the main components of Bile?

A

Bile is composed of bile salts (amphipathic molecules derived from cholesterol that emulsify fats), pigments (especially bilirubin from the breakdown of hemoglobin), and cholesterol.

38
Q

How do Bile and Pancreatic Lipase work together to digest fat?

A

Bile accomplishes mechanical digestion of fats, emulsifying them and increasing their surface area. Pancreatic Lipase accomplishes chemical digestion of fats, breaking their ester bonds.

39
Q

What are the 6 functions of the Liver?

A
  1. Processes nutrients (through glycogenesis and glycogenolysis, storage and mobilization of fats and gluconeogenesis)
  2. Produces urea
  3. Detoxifies chemicals
  4. Activates or inactivates medications
  5. Produces bile
  6. Synthesizes albumin and clotting factors
40
Q

The accessory organs of digestion originate from which primary germ layer?

A

As outgrowths of the gut tube, the accessory organs of digestion arise from embryonic endoderm.

41
Q

What are the three parts of the small intestine?

A
  1. Jejunum
  2. Illleum
  3. Duodenum
42
Q

Which parts of the small intestine are primarily involved in absorption?

A

Jejunum and Illeum

43
Q

What lines the small intestine?

A

Villi, which are covered with microvilli, increasing the surface area available for absorption.

44
Q

What are the two circulatory vessels in a villus? What biomolecules are absorbed into each?

A
  1. The Capillaries: absorb water-soluble nutrients like monosaccharides, amino acids, short-chain fatty acids, water-soluble vitamins, an water itself.
  2. The Lacteal: absorbs fat-soluble nutrients like fats, cholesterol, and fat-soluble vitamins.
45
Q

What are the 4 Fat-Soluble vitamins?

A

A, D, E and K

46
Q

What are the three components of the Large Intestine?

A

The cecum, colon and rectum.

47
Q

What is the main role of the Large Intestine?

A

Absorbs water and salts, forming semisolid feces.

48
Q

What does the Cecum do?

A

Te Cecum is an outpocketing that accepts fluid from the small intestine through the ileocecal valve and is the site of attachment of the appendix.

49
Q

What are the 4 portions of the Colon?

A

Ascending, transverse, descending and sigmoid portions.

50
Q

What is the role of the Rectum?

A

Stores feces, which are then excreted through the anus.

51
Q

What vitamins do gut bacteria produce?

A

Vitamin K and biotin (Vitamin B7)

52
Q

Cholera can produce up to 20L of watery diarrhea per day; given the symptoms does Cholera likely impact the small or large intestine?

A

While the large intestine’s main function is to absorb water, the small intestine actually absorbs a much larger volume of water. Thus, massive volumes of watery diarrhea are more likely to arise from infection in the small intestine.

MCAT - Biology (12 decks)

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