GI Part 1 & 2 Flashcards

(60 cards)

1
Q

What are the 4 basic layers of the alimentary canal?
From Inner–> outer

A
  1. Mucosa
  2. Submucosa
  3. Muscularis externa
  4. Serosa or Adventitia
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2
Q

What are the 3 sections in mucosa?

A
  1. Epithelium
    - stratified squamous or simple columnar
  2. Lamina propra
    - loose connective tissue
    - helps with absorption
    - Contains MALT
  3. Muscularis mucosae
    - smooth muscle
    - moves mucosa
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3
Q

What are some functions of mucosa?

A
  • SECRETES mucus, enzymes, hormones
  • ABSORBS end products of digestion
  • PROTECTS against infectious disease
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4
Q

Explain the submucosa layer.

Function?

A
  • Loose connective tissue
  • Has blood & lymphatic vessels

Function:
- support mucosa
- Binds layers together (loose connective)

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5
Q

What are the layers in the muscularis externa?
Function?

A
  1. Circular layer
  2. Longitudinal layer
  3. Myenteric nerve plexus

Function
- segmentation & peristalsis
- sometimes forms sphincters to control passage/prevent backflow

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6
Q

Explain process of Peristalsis

A
  • Circular muscle contract BEHIND bolus
  • Longitudinal muscles contract AHEAD of bolus
  • moves bolus forward
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7
Q

Explain the process of segmentation

A

Contracting & relaxing adjacent segment to move food forward and backward for mixing

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8
Q

Explain serosa layer. Function?

Which organs have the adventitia layer? Explain it.

A

Serosa
- loose connective tissue
- simple squamous
Function: permit mobility

Adventitia
- retroperitoneal organs
- dense irregular CT to bind organs together
- Lack mobility (anchored)

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9
Q

What is the peritoneum?
What is the peritoneal cavity?

A

Serous membrane of abdominal cavity

Peritoneal cavity
- between visceral & parietal peritoneum, fluid lubricates mobile organs

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10
Q

What are the intraperitoneal organs?
What do they have?

A

Mesentery
- double layer of peritoneum
- route for blood vessels, lymphatics & nerves
- Holds organs in place & stores fat

organs
- liver
-stomach
- ileum & jejunum
- transverse colon
- sigmoid colon

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11
Q

Differentiate between dorsal and ventral mesentery?

A

Dorsal
- allows access to all the blood vessels, lymphatics & nerves

Ventral
- for anchoring
- have low blood supply

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12
Q

Explain retroperitoneal organs.
Which organs are they

A

Lack mesentery
- resorbed & lost

Organs
- Duodenum
- Ascending colon
- Descending colon
- Rectum
- Pancreas

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13
Q

What type of fibres in the enteric nervous system link to CNS?

A

Afferent visceral fibers (to brain)

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14
Q

What 2 types of plexus’ are in the Enteric Nervous system?
Explain their function

A
  1. Myenteric nerve plexus
    - controls GI tract motility
  2. Submucosal nerve plexus
    - Regulates glands & smooth muscle (including BV) in mucosa
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15
Q

What are the 3 mechanisms that regulate & control digestive activities?

A
  1. Local factors
    - primary stimulus for digestive activities
    - Include: lumen pH, physical distortion , presence of chemicals
  2. Neural control
    - short reflex (myenteric plexus)
    - long reflex ( control large peristaltic waves)
  3. Hormonal control
    - produces enteroendocrine cells (digestive hormones)
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16
Q

What are some functions of saliva

A
  • cleanses mouth
  • moistens & dissolve food chemicals
    – Aids in bolus formation
    – Contains enzymes to begin digestion – Buffers pH (bicarbonate)
    – Lubrication
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17
Q

What types of cells are in the following

Submandibular
Parotid
Sublingual
Intrinsic glands

A

Submandibular: serous & mucous cells
(MOST OF total saliva volume)

Parotid: serous cells
Sublingual: mucous cells
Intrinsic glands: serous & mucous cells

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18
Q

What proteins and enzymes does saliva have?

A

Proteins:
- mucin, lysozyme, IgA, albumin

Metabolic wastes: urea & uric acid

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19
Q

What is the role of intrinsic glands vs extrinsic glands?

A

Intrinsic: keep mouth moist

Extrinsic:
- smell, taste, sight
- parasympathetics, CN IX, CN VIII

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20
Q

What is the hardest substance in the body?

A

enamel

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21
Q

What is dentin maintained by?

A

odontoblasts of pulp cavity

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22
Q

What is pulp?

A

connective tissue, blood vessels & nerves inside teeth

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23
Q

What is cementum anchored by?

A

periodontal ligament

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24
Q

What is the difference between the layers in the esophagus and alimentary canal?

A

-Mucosa is stratified squamous

  • submucosa is areolar connective tissue
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25
What are the phases of deglutition? (5)
1. - upper esophageal sphincter is contracted - tongue presses against hard palate - bolus forced into oropharynx 2. - uvula & larynx rise - epiglottis closes larynx - tongue blocks off anterior mouth - upper esophageal sphincter relaxes 3. - Constrictor muscles of pharynx contract (food forced into esophagus) - Upper esophageal sphincter contracts 4. Food moves through esophagus by peristalsis 5. Gastroesophageal sphincter opens (food enters stomach)
26
Why can infants breath & swallow at the same time?
- small oral cavity - tongue and palate is flatter - epiglottis is almost attached to the soft palate - the airway and foodway are separated except when swallowing Adult - larynx is lower - foodway and airway cross in the pharynx
27
What occurs during vomiting
-reverse peristalsis - glottis closes (prevents aspiration)
28
What is the digestive process in stomach (6)
1. Mechanical breakdown 2. Denaturation of proteins 3. Enzymatic digestion of proteins by pepsin 4. Secretes intrinsic factor 5. Absorption of lipid-soluble substances 6. Delivers chyme to small intestine
29
What does the stomach's relative unchanging pressure result from? What is stomach's response to filling?
Receptive relaxation - as food travels in esophagus, stomach muscles relax Gastric accommodation - intrinsic ability of smooth muscle to exhibit stress-relaxation
30
What does the mucosal protection contain in the stomach?
1. Layer of bicarbonate ( so stomach doesn't eat itself) 2. Tight junctions between epithelial cells 3. Damaged epithelial cells are quickly replaced by division of stem cells
31
Explain the parietal cell cell secretions (2)
1. Intrinsic factor - glycoprotein required for absorption of VitB12 in SI 2. HCl - stomach pH 1.5-3.5 - denatures protein in food - activates pepsin - Kills bacteria
32
How do parietal cells produce HCl
1. CO2 comes in parietal cell and makes HCO3 2. HCO3 leaves cell into blood, Cl- goes into cell. 3. Cl- leaves cell into stomach lumen and interacts with proton pump secreting H+ to make HCl
33
What are the 3 chemicals that regulate HCl secretion
ACh, histamine, gastrin
34
What do chief cells secrete? Why does the enzyme start off inactive?
Secrete pepsin activated by HCl & pepsin - inactive enzyme is pepsinogen - If active close to parietal cell, it will break down body protein
35
What do gastric enteroendocrine cells secrete?
chemical messengers into lamina propria
36
What do G cells secrete? Function?
Gastrin - Increase HCl secretion & intestine muscle contraction - Stimulates: - gastric emptying - parietal cell maturation - chief cells - Relaxes ileocecal valve & stimulates mass movements
37
What does enterochromaffin cells secrete (2) What function do they have?
Histamine: increase parietal cells HCl release Serotonin: increase contraction of stomach
38
What do Delta (D) cells secrete? Function?
Somatostatin - inhibits: - secretion from stomach & pancrease - SI absorption - gallblader & liver release of bile (shuts stomach stuff down)
39
What are the stimulatory & inhibitory events of regulation of gastric secretion (3)
1. Cephalic (reflex) phase: - few minutes prior to food entry 2. Gastric phase - food entering stomach to 3-4 hours layer - stimulates ALL types of cells 3. Intestinal phase - brief stimulatory effect as partially digested food enters duodenum, followed by inhibitory effects
40
Why are small intestines called that even though they are longer than large intestine
Have small diameter of lumen
41
What structural modifications do small intestines have to increase surface area
circular folds
42
What are paneth cells in intestinal mucosa
release antimicrobial agents to clean up at the end
43
What is the role of the duodenum?
Submucosa layer has a lot of duodenum cells which secretes HCO3 to neutralize pH of stomach. - Chyme is very acidic
44
What is the role of the jejunum
villi in here is the biggest to give absorption
45
What is the role of the ileum
- large # of lymphocytes - if there is any infections that make it this far
46
What are the requirements for digestion & absorption in the small intestine
1. Slow delivery of acidic, hypertonic chyme 2. Delivery of bile, enzymes, & bicarbonate ions from liver & pancreas 3. Mixing
47
when does ileocecal sphincter close and relax?
Closes - when chyme exerts backward pressure Relax - admit chyme into large intestine when: - gastroileal reflex enhances force of segmentation in ileum - Gastrin increases motility of ileum
48
What is the role of the falciform ligament in the liver
- Suspends liver from diaphragm & anterior abdominal wall (a mesentery)
49
Where does blood enter and exit in the liver?
Enter 1. Hepatic arteries 2. Hepatic portal veins Exit - hepatic veins
50
What are the liver lobules composed of?
Hepatocytes radiating from longitudinal central vein
51
What is the role of the Kupffer cells in the liver?
- macrophages to remove debris (bacteria, worn-out RBCs) - Act as a gate-keeper for immune responses
52
How many central veins does each portal lobule send blood to?
3
53
Which zone cells would be most impacted with systemic hypoxia (no O2 in tissues)?
Zone 3 cells since they are the closest to the central vein (CV)
54
What are the 6 hepatocyte functions?
1. Process blood borne nutrients 2. Synthesize & secrete hormones 3. Storage 4. Perform detoxification 5. Immune surveillance 6. Produce bile
55
Explain process blood borne nutrients function of hepatocyte
Use AA to make plasma proteins ( that our CV system needs) - albumins - A/B globulins for transport - make immune proteins & apoproteins
56
What do hepatocytes synthesize and secrete?
- insulin like growth factor - angiotensinogen - thrombopoietin - hepcidin
57
What do hepatocytes store?
- fat soluble vitamins (A, D, K, E) & vit B12 - iron & copper - store glucose as glycogen - fat
58
What detoxification do hepatocytes do?
Ammonia (NH3, toxi to CNS) --> Urea
59
What immune surveillance do hepatocytes do?
Kupffer cells destroy bacteria & clean up worn out erthrocytes - macrophages
60
Differentiate between primary acids and secondary bile acids
Primary acids - synthesized by liver from cholesterol Secondary bile acids - synthesized from primary bile acids by colonic bacterial enzymes