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Human Physiology > Unit 4 Ch. 21 > Flashcards

Unit 4 Ch. 21 Flashcards

1
Q

What are accessory digestive organs?

A

salivary glands, exocrine pancreas, liver and gallbladder

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2
Q

What is the GI tract composed of?

A
  • oral cavity (mouth/pharynx)
  • esophagus
  • stomach
  • small intestine (duodenum, jejunum, ileum)
  • large intestine (cecum, appendix, colon, rectum)
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3
Q

We are donuts

A

-Yes we are

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4
Q

What are the 4 layers of the digestive tract (innermost to outermost)

A

Inner to outer:

  • Mucosa
  • Submucosa
  • muscularis externa
  • serosa
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5
Q

What is the Mucosa composed of?

A
  • 3 layers, highly folded to increase SA for absorption
  • mucous membrane- protective surface, exocrine:digestive juice secretion, endocrine: secretion of Blood borne hormones
  • lamina propria- thin connective lymphoid
  • muscularis mucosa- thin smooth muscle, modifies folding pattern.
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6
Q

What is are the submucosa, muscularis externs, and serosa?

A
  • Submucosa: elasticic connective tissue. Contains blood and lymph
  • Muscularis externa: 2 layers and nerve network called myentric plexus
  • Serosa: CT covering secrets friction prevention fluid. Mesentery for proper position
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7
Q

What are the four basic digestive processes?

A
  • Motility: mixing
  • Secretion: addition of organic digestives
  • Digestion: biochemical breakdown
  • Absorption: transfer from GI to blood (or lymph)
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8
Q

How does the digestive system establish motility?

A

2 types of movement:

  • propulsive: pushes content forward
  • mixing: exposing surface area for breakdown. No net movement.
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9
Q

What’s true of secretions?

A
  • energy requirement due to active transport and synthesis of secretory products.
  • Material taken from blood to form secretions, then returned later.
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10
Q

How is digestion accomplished?

A
  • Accomplished by hydrolysis (add H2O at binding sites)
  • Proteins -> amino acids
  • Fats (triglycerides)-> monoglycerides
  • carbs-> monosaccharides
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11
Q

Where does absorption occur?

A
  • small intestine

- uptake of small absorbable units

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12
Q

What is saliva?

A
  • Mostly water (95%) then protein and electrolytes
  • amylase (maltose), mucus (lube), lysozyme (antibacterial)
  • AIDS SPEECH
  • cleans mouth
  • neutralizes acids. (mouth slightly acidic)
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13
Q

Salivary reflex?

A
  • simple: chemoreceptors and -pressurereceptors with food

- conditioned: no food necessary

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14
Q

What are the two stages of swallowing?

A
  • oropharyngeal stage: mouth to pharynx to esophagus
  • esophageal stage: esophagus to stomach (cant stop)
  • all or none, medulla center stimulated
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15
Q

What is the oropharyngeal stage of swallowing?

A
  • tongue prevents re-entering of bolus
  • uvula is elevated to seal nasal passage
  • glottis closes and epiglottis folds over glottis
  • Swallowing center inhibits breathing
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16
Q

What is the esophageal stage of swallowing?

A
  • peristaltic wave pushes bolus forward

- lodged bolus triggers secondary peristaltic wave

17
Q

What is the basic anatomy of the stomach?

A
  • Gastroesophageal sphincter: prevents stomach contants to esophagus
  • Fundus: thin smooth muscle, top part
  • Body: main part, thin smooth muscle
  • Antrum: lowest portion, thick smooth muscle
  • pyloric sphincter: barrier between stomach and duodenum
18
Q

What is the functional role of the stomach?

A
  • Food storage
  • HCl secretion and enzymes to begin protein digestion
  • Pulverize and mix to produce chyme
19
Q

What are the 4 aspects of gastric motility?

A
  • Filling: 20x expansive.
  • Storage
  • Mixing: Peristaltic contractions produce chyme. Strongers ones push food through pyloric sphincter.
  • Emptying
20
Q

What factors affect gastric emptying?

A
  • Stomach: amt./ fluidity of chyme

- Dudodenum: Fat (Slow process), Acid (inactivates pancreatic enzymes), Hypertonicity, Distension (too much chyme)

21
Q

The following are located in the oxyntic mucosa (body and fundus). What do they do/secrete?

  • Mucuous cells
  • Chief cells
  • Parietal cells
  • Stem Cells
  • Surface epithelial cells
A
  • Mucuous cells: mucus and HCO3-
  • Chief cells: pepsinogen, gastric lipase
  • Parietal cells: HCl(activates pepsin) and intrinsic factor (B12)
  • Stem cells: parent cells for all mucosa cells
  • epithelial cells: thick, viscous alkaline mucus
  • D Cells: somatostatin, inhibits acid secretion
  • G cells: gastrin, acid secretion
22
Q

What is located in the pyloric gland area (antrum)?

A
  • Glands that secrete mucus/pepsinogen

- NO HCl

23
Q

What is the role of HCl in the stomach?

A
  • secreted by parietal, carbonic anhydrase
  • doesn’t digest
  • activates pepsinogen
  • denatures proteins/kills microorgs
24
Q

What is the role of pepsin?

A
  • pepsin digests proteins
  • pepsinogen stored in chief cells
  • HCl cleaves to activate
  • pepsin is autocatalytic
25
Q

What is the role of mucus?

A
  • lubrication
  • protection from stomach eating itself
  • neutralizes HCl
  • alkaline
26
Q

What are the hormones of the stomach? Which hormone inhibits the other ones?

A
  • Gastrin: G cells, secreted into blood, promotes HCl and pepsinogen secretion, stimulated by ACh
  • Histamine: secreted by ECL cells in oxyntic mucosa, responds to ACh and gastrin, increases HCl secretion (paracrine)
  • Somatostatin: D cells, negatively acts on parietal, G, and ECL cells
27
Q

What is the role of the pancreas?

A

-Endocrine (islets): insulin/glucagon
-Exocrine (acinar):
proteolytic enzymes (trypsin is auto catalytic, released in inactive form)
pancreatic amylase (conversion to maltose, released in active form)
pancreatic lipase (fatdigestion, released in active form)
sodium bicarbonate (duct cells, neutralizes chyme)

28
Q

What are the roles of secretin and cholecystokin (CKK)?

A
  • Secretin: stimulates bicarbonate release in response to acidity
  • CKK: stimulates release of digestive enzymes in response to fat/protein
29
Q

What is the role of the liver?

A
  • produces bile
  • bile is STORED and CONCENTRATED in gall bladder
  • bile salts emulsify fats to aid in its digestion (cholesterol derivatives)
30
Q

How do bile salts emulsify fat?

A
  • Increase SA
  • prevent coalescing of fat droplets
  • form micelles
  • help with absorption of fat and lipid soluble vitamins
31
Q

What is the role of the small intestine?

A
  • modified to increase SA
  • location of most absorption
  • Circular folds increase SA 3x
  • Circular folds have villi increase SA 10x
  • Villi have microvilli that increase SA 20x
32
Q

How are carbs absorbed?

A

glucose polymers digested by amylase to disaccharides:
maltose (2gluc), sucrose(gluc/fruc), and lactose(gluc/galact)
-Glucose with Na+ SGLT sumporter

33
Q

How are proteins absorbed?

A
  • Endopeptidase internal peptide bond digestion

- Exopeptidase digests terminal peptide bonds to release amino acids

34
Q

How are fats absorbed?

A
  • Bile salts coat
  • Pancreatic lipase and colipase breaks fats into monoglycerids and fatty acids
  • Fats enter cells by diffusion
  • Fat/cholesterol/protein combine to form chlyomicrons
  • Released into lymphatic system
35
Q

What is the role of the large intestine?

A
  • Chyme consists of undigestible stuff at this poind
  • Dehydrates poop. Na+ absorbe and Cl- and H2O follow osmotically.
  • Stores poop
  • Alkaline mucus to protect intestines from bacterial fermentation acids

Human Physiology (9 decks)

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