FINAL - Digestion Flashcards

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1
Q

Outline why food needs to be digested.

A
  • Macromolecules must be broken down into smaller molecules so they are small enough to be absorbed into your bloodstream
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2
Q

Explain how starch is digested.

A
  • Hydrolyzed into maltose in the small intestine by amylase produced by the pancreas
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3
Q

Explain how proteins are digested.

A
  • Hydrolyzed into peptides in the stomach by pepsin produced by the gastric glands
  • Hydrolyzed into amino acids in the small intestine by protease produced by the pancreas
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4
Q

Explain how fats are digested.

A
  • Hydrolyzed into glycerol and fatty acids in the small intestine by lipase produced by the pancreas
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5
Q

Explain the nervous and hormonal mechanisms that control the secretion, volume, and content of gastric sections.

A
  • Smell/sight of food causes brain to send nerve impulses via vagus nerve to medulla
  • glands in stomach secrete gastric juice
  • chemo- / stretch receptors in stomach wall detect food
  • releases gastrin hormone; stimulates secretion of acid
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6
Q

Outline the roles of the stomach.

A
  • Produces acid to break down molecules
  • Churns food in mechanical digestion
  • Produces protease/pepsin to digest proteins
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7
Q

Outline the roles of HCl in the stomach.

A
  • Kills bacteria
  • Activates pepsin into pepsinogen for protein digestion
  • Maintains low pH of stomach
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8
Q

Outline the causes, consequences, and treatment of stomach ulcers.

A

Cause: Helicobacter pylori infection
Cons: digestion of stomach lining by HCl (stomach ulcers), inflammation
Treatment: PPIs, antacids to decrease acidity

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9
Q

Outline the use of PPI’s to reduce stomach acid secretion.

A
  • Acidity achieved by proton pumps
  • PPIs bind irreversibly to proton pumps
  • Lowers amount of acid produced
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10
Q

Describe how the structure of a villus is adapted to its function.

A

Function: Efficient absorption of nutrients in the small intestine
Epithelial cells - surround each villus (decreases diffusion distance for nutrients into bloodstream)
Rich Capillary Network - large concentration gradient (between blood and the fluid in the small intestine)
allows for rapid absorption of nutrients
Lacteals - Absorb lipids (into lymphatic system – transports fats, drains tissues of excess fluids)
Intestinal crypts - release juices that act as ‘carrier fluids’ for nutrients

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11
Q

Describe the method of transport used to absorb the products of starch digestion in the small intestine.

A

Facilitated diffusion - movement through channel proteins

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12
Q

Describe the method of transport used to absorb the products of protein digestion in the small intestine.

A

Active transport - against concentration gradient using proton pumps

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13
Q

Describe the method of transport used to absorb the products of lipid digestion in the small intestine.

A

Endocytosis - by means of vesicles (lipoprotein particles)

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14
Q

Distinguish between exocrine and endocrine glands (with regard to their structure and function)

A

Exocrine glands - secretes substances through ducts / secretory cells to an epithelial surface (salivary glands, gastric glands)
Endocrine glands - secretes hormones into the bloodstream (liver)

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15
Q

Outline the benefits of a diet rich in fiber.

A
  • Prevents constipation
  • Decreases hunger so less obesity
  • Ensures correct movement of food through intestines
  • Decreased risk of colon cancer
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16
Q

State which substances are egested by the human body.

A

BELCH
Bile pigments
Epithelial cells
Lignin
Cellulose
Human microflora

17
Q

Outline the effects of the cholera toxin.

A
  • V. cholerae produces toxin
  • Toxin causes ions to be pumped into small intestine
  • Drawing water thru osmosis into intestine
  • Leading to dehydration, diarrhea, vomiting
18
Q

Explain how the pancreas maintains homeostatic levels of glucose in the blood.

A
  • Homeostasis is the maintenance of a constant internal environment
  • Negative feedback controls glucose levels
  • Pancreas produces hormones that regulate levels of glucose
  • If glucose lvls are high, beta-cells produce insulin
  • Insulin causes cells to take up glucose (lowers lvls)
  • Liver stores excess glucose as glycogen
  • If blood/glucose levels are low, alpha-cells produce glucagon
  • Glucagon causes liver two break down glycogen into glucagon (increases lvls)
19
Q

Explain the causes, consequences, and treatment of Type I diabetes.

A

Cause: Autoimmune reaction, beta cells of pancreas become destroyed
Cons: high blood sugar, glucose in urine
Treat: insulin injections

20
Q

Explain the causes, consequences, and treatment of Type II diabetes.

A

Cause: obesity, lack of exercise
Cons: desensitized to insulin
Treat: consume complex carbs for gradual release of glucose into blood, eat more high fiber foods to satisfy appetite but not get absorbed, reduce intake of fats to reduce weight.

21
Q

Outline the dual supply of blood to the liver.

A
  • It is blood from hepatic artery and hepatic portal vein
  • Blood in hepatic artery provides oxygen to liver
  • Hepatic vein carries blood rich in nutrients from intestines
  • Allows glucose to be stored and released in response to hormones
22
Q

Explain how the liver regulates nutrient levels in the blood (including nutrients that are stored by the liver).

A
  • Liver stores glucose as glycogen (iron is also stored)
  • Releases glucose under influence of insulin or glucagon depending on blood/glucose levels
  • Kupffer cells break down red blood cells by phagocytosis
  • Hemoglobin slept into heme/globin
  • Iron from heme carried to bone marrow
  • Excess cholesterol converted to bile salts
23
Q

Explain how the liver breaks down and recycles the components of erythrocytes (red blood cells).

A
  • Erythrocytes rupture after 120 days
  • Kupffer cells in sinusoids of the liver
  • Kupffer cells ingest erythrocytes
  • Hemoglobin split into heme and globin groups
  • Heme group broken down into iron and bilirubin
  • Irons stored in liver / Bilirubin becomes part of bile
24
Q

Outline the production of bile and the causes and consequences of jaundice.

A
  • Erythrocytes broken down in liver
  • Heme group converted to bilirubin
  • Bilirubin transferred to bile and eliminated in feces
  • Jaundice;
    Caused: by blockage of bile ducts
    Cons: liver does not excrete bilirubin, bilirubin accumulates in the blood