Chapter 65 - Guyton Flashcards

1
Q

The chemistry of digestion is simple because, in the case of all three major types of food, the same basic process of ________ is involved.

A

hydrolysis

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2
Q

Major carbohydrates in the diet.

A

sucrose, lactose, starches

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3
Q

ptyalin

A

alpha-amylase (secreted mainly by the parotid gland)

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4
Q

Represents more than 80% of the final products of carbohydrate digestion.

A

glucose

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5
Q

What is the importance of pepsin in protein digestion?

A

it can break down collagen, the primary binding constituent of intracellular connective tissue of meats

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6
Q

Within 15-30 minutes after the chyme empties from the stomach into the duodenum and mixes with pancreatic juice, virtually all the ___________ will have become digested.

A

carbohydrates (pancreatic juice has high amylase which will complete CHO digestion)

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7
Q

Lactose

A

glucose + galactose

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8
Q

Sucrose

A

glucose + fructose

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9
Q

Maltose

A

glucose + glucose

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10
Q

Where are lactase, sucrase, and maltase located?

A

in the enterocytes covering the intestinal microvilli brush border

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11
Q

Most protein digestion occurs under the influence of proteolytic enzymes from pancreatic secretion..where does this occur?

A

in the upper small intestine, in the duodenum and jejunum

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12
Q

This enzyme is important in the final stage of protein digestion occurring in the cytosol of the enterocyte (cleaving the tripeptides and dipeptides into amino acids).

A

peptidase

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13
Q

Most abundant fats of the diet.

A

triglycerides

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14
Q

Perform the detergent function for the digestion of fats.

A

bile salts and lecithin

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15
Q

The most important enzyme for the digestion of triglycerides.

A

pancreatic lipase

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16
Q

The bile salt _______ act as a transport medium to carry the monoglycerides and free fatty acids to the brush borders of the intestinal epithelial cells.

A

micelles

17
Q

valvulae conniventes (or folds of Kerckring)

A

increase the surface area of the absorptive mucosa of the small intestine

18
Q

Which three structures increase the absorptive surface area of the mucosa.

A

folds of Kerckring, villi, microvilli

19
Q

Water is transported through the intestinal membrane entirely by?

A

diffusion

20
Q

When a person becomes dehydrated, this hormone is secreted and greatly increases sodium (and water) reabsorption throughout the intestinal tract.

A

aldosterone

21
Q

Bicarbonate secreted by the intestinal membrane is often exchanged for absorption of which ion?

A

chloride

22
Q

This hormone activates vitamin D and then vitamin D causes increased calcium absorption.

A

parathyroid hormone

23
Q

Glucose is actively transported inside the cell by what mechanism?

A

sodium co-transport

24
Q

Fructose and a few amino acids do not require sodium co-transport but instead are absorbed through which mechanism?

A

facilitated diffusion

25
Q

How are short and medium-chain fatty acids absorbed?

A

direct diffusion of these short-chain fatty acids from the intestinal epithelial cells directly into the capillary blood of the intestinal villi (do not require lymphatics)

26
Q

How are triglycerides ultimately absorbed?

A

micelles to get into cells then released in the form of chylomicrons through the base of the epithelial cell, to flow upward through the thoracic lymph duct and empty into the circulating blood

27
Q

The primary function of the proximal colon versus distal?

A

absorption; storage

28
Q

Absorption of sodium and chloride ions creates an osmotic gradient across the large intestinal mucosa, which in turn causes absorption of?

A

water