Chapter 24 - Digestive System Flashcards

1
Q

Functions of Digestive System

A
  1. ingestion - intake of food
  2. digestion - mechanical and chemical breakdown
  3. absorption - uptake of nutrients
  4. compaction - absorption of water, consolidation of indigestible residue
  5. defecation - elimination of feces
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2
Q

Alimentary Canal

A

mouth through anus

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3
Q

Gastrointestinal (GI) Tract

A

stomach and intestines

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4
Q

Enteric Nervous System

A
  • nervous network exclusive to the esophagus, stomach, and intestines
  • submucosal plexus (submucosa) - controls movements of the muscularis mucosae and glandular secretions
  • myenteric plexus (between layers of the muscularis externa) - controls peristalsis and other contractions of the muscularis externa
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5
Q

Accessory Organs of the Digestive System

A
  • teeth
  • tongue
  • salivary glands
  • liver
  • gall bladder
  • pancreas
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6
Q

General Histology

A
  • Mucosa
    • Epithelium
    • Lamina propria (loose connective tissue)
    • Muscularis mucosae (smooth muscle)
  • Submucosa (loose connective tissue with vessels and nerves)
  • Muscularis Externa (smooth muscle for propulsion and mixing, inner circular layer & outer longitudinal layer)
  • Serosa or Adventitia (areolar tissue topped with simple squamous mesothelium)
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7
Q

Mesenteries

A

connective tissue sheets holding abdominal viscera in place

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8
Q

Posterior and Anterior Messenteries

A

two-layered membrane that may hang freely or connect organs together or to abdominal wall

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9
Q

Lesser Omentum

A

messentery, extend from lesser curvature of stomach to liver

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10
Q

Greater Omentum

A

messentery, hangs down like an apron from stomach’s greater curvature

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11
Q

Mesocolon

A

messentery of the colon

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12
Q

Mouth

A
  • oral (buccal) cavity
  • oral fissure to fauces
  • cheeks and lips
    • labial frenulum - median fold attaching lip to gum
    • vestibule - space just inside lips and cheeks
  • palate
    • hard (bony)
    • soft - include uvula
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13
Q

Tongue

A
  • lingual papillae (vallate, foliate, fungiform)
  • body - anterior 2/3
  • root - posterior 1/3
  • lingual frenulum - attachment to floor of mouth
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14
Q

Teeth

A
  • “Dentition”
  • incisors - chisels
  • canines - puncture and shred
  • premolars and molars - crush and grind
  • 20 deciduous vs. 32 permanent
  • embedded in mandible and maxilla
    • alveolus - socket
    • periodontal ligament
    • cementum of root
  • gingiva surrounds neck
  • internal structures
    • dentin
    • pulp cavity, root canal (spaces for nerves and vessels)
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15
Q

Salivary Glands

A
  1. parotid - near ear
  2. sumandibular - under jaw
  3. sublingual - under tongue
    - tubuloacinar structure
    - mucous and serous cells
    - saliva contains:
    • amylase and lipase
    • mucus
    • lysozyme
    • immunoglobulin A
    • electrolytes
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16
Q

Pharynx and Esophagus

A
  • oropharynx and laryngopharynx pass food
    • walls contain skeletal muscle
    • nonkeratinized stratified squamous epithelium
  • esophagus is posterior to trachea
    • starts behind larynx
    • passes through esophageal hiatus of diaphragm
    • ends at lower esophageal sphincter located at the cardiac orifice to stomach
  • digultation = swallowing, coordinated by swallowing center of medulla
17
Q

Microscopic Anatomy of the Stomach

A
  • gastric pits of mucous with glands
    • mucous cells - mucus
    • regenerative cells - new cells
    • parietal cells - HCl, intrinsic factor, Ghrelin
    • chief cells - pepsinogen, gastric lipase
    • enteroendocrine cells - hormones, gastrin
18
Q

Duodenum

A
  • first 10in. of small intestine
  • receives and mixes stomach contents, pancreatic juice, and bile
  • major duodenal papilla for bile and pancreatic ducts
  • minor duodenal papilla for accessory pancreatic duct
  • Brunner’s (duodenal/submucosal) glands with bicarbonate rich mucous
19
Q

Jejunum

A
  • 8ft. middle portion of small intestines
  • mostly within umbilical region
  • most digestion and absorption occur here
  • circular folds (plicae circulares)
20
Q

Ilieum

A
  • 13ft distal portion of small intestitnes
  • sparse folds, pink color
  • Peyer patches - lymphatic nodules
  • ileocecal junction, ileocecal valve
21
Q

Microscopic Anatomy of Small Intestine

A
  • villi
    • enterocytes (absorptive cells) have tiny microvilli projections
    • goblet cells
    • lacteals - lymphatics for lipid absorption
  • intestinal crypts - goblet cells and absorptive cells
    • Paneth cells - enteroendocrine; secrete lysozyme
22
Q

Microscopic Anatomy of Large Intestine

A
  • mostly simple columnar, except anus (nonkeratinized stratified squamous epithelium)
  • has intestinal crypts but no villi or circular folds
  • abundant lymphatic tissue
  • mucosa specialized for fluid and electrolyte absorption
23
Q

Liver

A
  • body’s largest gland
  • over 200 functions
    • hematological, metabolic, storage, immunity
    • digestive function is bile production
      • bilirubin - decomposition of hemoglobin
      • urobilogen - metabolized bilirubin (feces brown)
      • bile acids/lecithin - emulsify fats
24
Q

Microscopic Anatomy of the Liver

A
  • hepatic lobules - small cylinders w/ central vein, radiating plates of hepatocytes
    • hepatic sinusoids - leaky capillaries
    • hepatic macrophages - (Kupffer cells) clean blood
    • bile canaliculi -> bile ductules -> right/left hepatic ducts
25
Q

Liver Circulation

A
  • hepatic portal vein - brings nutrient rich blood from veins of GI tract to liver
  • hepatic artery
    • brings arterial blood to liver
    • aorta -> celiac truck -> common hepatic a. -> hepatic artery proper -> hepatic a.
  • hepatic veins - exit from top of liver and empty into inferior vena cava
26
Q

Gallbladder

A
  • sac on underside of liver
  • stores and concentrates bile
  • fundus (head), cervix (neck)
  • cystic duct
27
Q

Bile Passages

A
  • two hepatic ducts merge -> common hepatic duct
  • common hepatic duct + cystic duct (from gallbladder) -> bile duct
  • bile duct + pancreatic duct -> hepatopancreatic ampulla at major duodenal papilla
28
Q

Pancreas

A
  • retroperitoneal - posterior to stomach
  • head (near duodenum), tail (near spleen)
  • endocrine islets secrete insulin and glucagon
  • mostly exocrine tissue secreting pancreatic juice
    • enzymes, zymogens (inactive precursors of enzymes), sodium bicarbonate, water, and electrolytes
  • branching ducts
    • pancreatic duct
    • accessory pancreatic duct - opens at minor duodenal papilla
  • acinar cells (exocrine)