ch 9 - The Digestive System Flashcards Preview

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Flashcards in ch 9 - The Digestive System Deck (66)
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1

Intracellular digestion

part of metabolism, involves oxidation of glucose and fatty acids for energy

2

extracellular digestion

process by which nutrients are obtained from food, occurs in lumen of alimentary canal (which runs from mouth to anus and is sectioned off by sphincters - circular smooth muscles)

3

Digestion vs. absorption

digestion is breakdown of food into organic molecules; absorption is transport of products of digestion from digestive tract to circulatory system for distribution to body's tissues and cells

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mechanical digestion

physical breakdown

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chemical digestion

enzymatic cleavage of chemical bonds

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digestive tract

oral cavity - pharynx - esophagus - stomach - small intestine - large intestine - rectum

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organs that assist digestion by secreting enzymes and lubricants

salivary glands, pancreas, liver, gallbladder

8

enteric nervous system

collection of one hundred million neurons that govern function of the GI system; they trigger peristalsis; can function independently of brain and spinal cord but is heavily regulated by autonomic NS

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hormones involved with feeding behavior

antidiuretic hormone (ADH or vasopressin), aldosterone, glucagon, ghrelin, leptin, and cholecystokinin

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hormones that promote thirst

ADH and aldosterone

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hormones that promote hunger

Glucagon secreted by pancreas, and ghrelin secreted by stomach and pancreas

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hormones that promote satiety

leptin and cholecystokinin

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mastication

chewing

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salivary amylase

enzyme present in saliva that hydrolyzes starch into smaller sugars (maltose and dextrins)

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lipase

enzyme present in saliva that catalyzes hydrolysis of lipids

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three parts of the pharynx

nasopharynx (behind nasal cavity), oropharynx (behind mouth), and laryngopharynx (above vocal cords)

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control of esophagus

top third is skeletal muscle which means it is somatic (voluntary), the middle third is a mix of this and smooth muscle, the bottom is all smooth muscle which is under autonomic control

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sphincter that initiates swallowing

upper esophageal sphincter

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sphincter right above stomach

lower esophageal sphincter (or cardiac sphincter)

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capacity of stomach

2 L

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four main anatomical divisions of the stomach

fundus and body, which contain mostly gastric glands; and antrum and pylorus, which contain mostly pyloric glands

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rugae

folds of the lining of the stomach

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gastric gland cell types

mucous cells (produce bicarbonate rich mucus that protects the muscular walls from strong acid pH 2 and proteolytic environment), chief cells (secrete pepsinogen), and parietal cells (secrete hydrogen ions)

24

gastric juice

comprised of secretions from 2 or three gastric gland cells - pepsinogen secreted by chief cells - a proteolytic enzyme (the zymogen or inactive form of pepsin), and hydrogen ions secreted by parietal cells as hydrochloric acid which cleave pepsinogen to pepsin

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pepsin

digests protein by cleaving peptide bonds near aromatic amino acids, resulting in short peptide fragments, activated by acidic environment

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intrinsic factor

glycoprotein secreted by parietal cells involved in proper absorption of vit B12

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pyloric glands

contain G-cells which secrete gastrin (a peptide hormone).

28

Gastrin

induces parietal cells in the stomach to secrete more HCl and signals the stomach to contract, mixing contents

29

chyme

digestion of solid food in stomach results in acidic, semifluid mixture

30

small intestine segments

duodenum, jejunum and ileum