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Physiology > GI 1 > Flashcards

GI 1 Flashcards

1
Q

components of the GI system (2)

A
  1. Alimentary Canal (GI Tract)

2. Accessory organs

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2
Q
  1. Alimentary Canal (GI Tract) (3)
A

Mouth to anus
Lumen Contents considered outside body
30 feet in length

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3
Q
  1. Accessory organs (2)
A

Not part of GI tract

Produce substances secreted into tract

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4
Q

Produce substances secreted into tract (3)

A

Salivary glands
Exocrine pancreas
Liver and Gall Bladder

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5
Q
  1. Digestion
A

Breakdown ingested molecules into building blocks

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6
Q

Two Types of digestion

A

A. Mechanical

B. Chemical

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7
Q
  1. Secretion (3)
A

Digestive enzymes
Acid/Base
Bile

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8
Q
  1. Absorption (2)
A

Passive and Active transport processes

Moves substances from lumen of gut to blood

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9
Q
  1. Motility (3)
A

Mixing
Mechanical Digestion
Move material through tract

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10
Q
  1. Excretion (2)
A

Removal of Metabolic waste

Very little true waste in Feces (Bile pigments)

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11
Q
  1. Defense (1)
A

Gut Associated Lymphoid Tissue

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12
Q

Nutrients ingested substances (7)

A 
Carbohydrates
Fats
Proteins
DNA, RNA
Water
Electrolytes
Vitamins
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13
Q

Other ingested substances (5)

A 
Pathogens
Alcohol
Drugs (Licit, Illicit)
Toxins
Coins, Toys, Bugs
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14
Q

Four Layers

A
  1. Mucosa
  2. Submucosa
  3. Muscularis Externa
  4. Serosa
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15
Q
  1. Mucosa (3)
A

Simple Columnar Epithelium
Lamina Propria
Muscularis Mucosa
-Movement of Villi

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16
Q
  1. Submucosa (3)
A 
CT Layer
Blood and lymph vessels
Submucosal Plexus 
Network of neurons
-Projections to luminal surface cells, muscularis mucosa, and to -Myenteric plexus
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17
Q
  1. Muscularis Externa (3)
A 
Circular Muscle
-Contraction narrows lumen
Longitudinal muscle
-Contraction shortens tube
Myenteric Plexus
-Network of neurons
-Input from Autonomic NS
-Projections to Submucosal Plexus, Circular, and Longitudinal muscle
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18
Q
  1. Serosa (2)
A

CT covering

Support GI tract in abdominal cavity

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19
Q

Epithelial layer (4)

A

Simple Columnar (microvilli)
Goblet Cells
Enteroendocrine cells (base of villi)
Stem cells

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20
Q

Tremendous surface area available for absorption of materials from lumen (3)

A

Circular Folds
Villi
Microvilli (Brush Border)
-Increases SA 600x over flat surface

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21
Q

Inside Villus (2)

A

Lacteals (lymph vessels)

Capillary network

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22
Q

Control Systems regulate conditions in

A

lumen of tract (not ECF conditions)

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23
Q

Control mechanisms are governed by

A

volume and composition of luminal contents

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24
Q

Afferent (Sensory)

(3)

A
  • Responds to stretch, inflammation, nutrients, endocrine factors.
  • Synapses in enteric nervous system, prevertebral ganglia, spinal cord, brainstem.
  • Vagal nerves mainly afferent to brainstem.
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25
Q

Efferent (Secretomotor) (3)

A

somatic
sympathetic
parasympthetic

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26
Q

Somatic –

A

CN XII (tongue), V (chewing), IX, X (swallowing); Pudendal n. – ext. anal sphincter

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27
Q

Sympathetic –

A

post-ganglionic fibers (NEpi) to enteric nervous system, vasculature, ducts, parenchyma; usually inhibitory.

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28
Q

Parasympathetic (vagus, pelvic) –

A

ENS functions as post-ganglionic fibers, actions are stimulatory or inhibitory, depending on final neurotransmitter receptor.

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29
Q 
Enteric Nervous System (ENS)“The Brain in the Gut” 
Myenteric plexus (2)
A

Linear chain of neurons that extend the entire length of GI Tract
Control muscle of muscularis externa

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30
Q

When ENS is stimulated (5)

A

Increase tone of gut wall
Increase intensity of rhythmic contractions
Slight increase in rate of rhythmic contractions
Increase conduction velocity of electrical waves along gut wall
Inhibition of sphincter contraction

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31
Q

submucosal plexus controls function of each minute segment of tract
Local control of (3)

A

Intestinal secretions
Absorption
Contraction of mucosal muscle

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32
Q

Endocrine Regulation of Digestive Function (4)

A

Endocrine cells scattered in gut mucosa.
Specialized cells: one cell – one hormone (mostly).
Specific cell types localized to regions of gut.
Cells “taste” luminal contents.

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33
Q

Paracrine Factors (3)

A

Cells similar to endocrine.

Released into interstitial fluid, diffuses to target (may “overflow” into the circulation).

Two established gut paracrine factors: histamine (ECL cell), somatostatin (D cell).

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34
Q

Histamine is mainly released by

A

gastrin

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35
Q

Somatostatin is mainly released by

A

luminal H+

36
Q

skipped

Patterns of Motility (8)

A 
Chewing
Swallowing
Esophageal transport
Gastric storage, trituration, emptying
Vomiting
Gallbladder storage, emptying
Small intestinal mixing & transport
Colonic storage, defecation
37
Q

Skeletal (voluntary, striated) –

A

mouth, oropharynx, upper esophageal sphincter, upper 1/3 of esophagus, external anal sphincter.

38
Q

Smooth (involuntary) –

A

lower 2/3 of esophagus, stomach, small intestine, large intestine, gallbladder, biliary and pancreatic ducts.

39
Q

Importance of Portal Vein (2)

A

Collects all venous outflow from most GI organs.

All portal outflow goes to liver before entering vena cava.

40
Q

All portal outflow goes to liver before entering vena cava.

A

Nutrients, hormones, drugs, toxins “scanned” by liver.

41
Q

Types of Saliva (2)

A

serous

mucus

42
Q
  1. Serous (3)
A

Watery secretion containing ptyalin (α amylase)
Moisten and dissolve food
Small amount of chemical digestion

43
Q
  1. Mucus (2)
A

Thick secretions containing mucin

Lubrication and protection of surfaces

44
Q

Types of Salivary Glands (4)

A

Parotid - Serous Gland
Submandibular - Mixed
Sublingual - Mixed
Many tiny buccal glands - Mucus

45
Q

Constituent: water
Function:

A

Facilitates taste and dissolution of nutients, aids in swallowing

46
Q

Constituent: bicarbonate
Function:

A

Neutralizes refluxed gastric acid

47
Q

Constituent: mucins
Function:

A

Lubrication

48
Q

Constituent: amylase
Function:

A

Starch Digestion

49
Q

Constituent: lysozyme, lactoferrin, igA
Function:

A

Innate and acquired immunity

50
Q

Constituent: epidermal and nerve growth factors
Function:

A

? Mucosal growth and protection

51
Q

Saliva

Produce up to – L/day..

A

1.5

52
Q

Secretion strictly under — reflex control.

A

neural

53
Q

Parasympathetic NS (Ach/Muscarinic Receptors) (4)

A

Predominate regulator of saliva production
Critical for initiation of saliva secretion
Critical for sustaining high levels of saliva secretion
Vasodilation of blood vessels supplying salivary glands

54
Q 
Parasympathetic NS (Ach/Muscarinic Receptors)
Causes:
A

Up to 20x increase in saliva production by acinar cells

55
Q

Reflex Activation of Parasympathetic Stimulated Saliva Production (4)

A

Taste (especially sour) and tactile stimuli (presence of smooth objects) on tongue surface
Smell of food (especially if it is a food that is not liked)
Ingestion of irritating foods
Nausea

56
Q

Sympathetic NS (NE/Adrenergic receptors) (2)

A

Minor role

Potentiates Parasympathetic effects

57
Q

As flow rate increases, the saliva: (2)

A

more closely resembles the plasma (less hypotonic)

Becomes more basic

58
Q

Unstimulated Salivation (3)

A

69% submandibular glands
26% parotid glands
5% sublingual glands

59
Q

Saliva Inhibited by: (4)

A

Fear
Sleep
Fatigue
Dehydration

60
Q

Stimulated Salivation (3)

A

69% Parotid
26% submandibular
5% sublingual

61
Q

Stimulated by: (5)

A 
Autonomic (primarily parasympathetic)
Thinking/seeing/smelling food
Conditioned salivation
Chewing
Nausea
62
Q

Rates of saliva production are not dependent on —, flow rates remain constant in spite of

A

age

acinar degeneration

63
Q

SALIVARY GLAND DYSFUNCTION- XEROSTOMIA

A

Subjective feeling of a dry mouth.

64
Q

SALIVARY GLAND DYSFUNCTION- XEROSTOMIA

most common causes (5)

A 
Polypharmacy (>4 drugs/day)
Anxiety and depression (and medications used for treatment)
Insufficient hydration
Radiation to the head and neck
Sjogren syndrome
65
Q

Sjogren syndrome (3)

A

Autoimmune destruction of mucous membranes and moisture-secreting glands
Decreased production of tears and saliva
Dry eyes and mouth

66
Q

skipped

CONSEQUENCES AND MANAGEMENT OF XEROSTOMIA (7)

A

Increased caries due to reduced oral clearance of sugars, dietary acids, oral bacteria
Halitosis
Disrupted sleep due to dry mouth; wake up to sip water and moisten mouth
Difficulty lubricating and swallowing food
Dry mouth (feel thirsty, dry, cracked lips)
Impaired sense of tastes
Heartburn

67
Q

Dry mouth (feel thirsty, dry, cracked lips) (2)

A

Burning mouth sensation

Dry/sore oral mucosa

68
Q

Heartburn (3)

A

Low saliva; decreased buffering
Loss of protective growth factors in saliva
Lengthened healing time for ulcers

69
Q

Management (4)

A

Avoid acidic, spicy, crunchy and coarse foods.
Alcohol-free toothpastes and rinses.
Oral moisturizers, sips of water, sugarless chewing gum.
Sialogogues such as pilocarpine and cevimeline before meals (cholinergic agonists)

70
Q

MASTICATION

A

Rhythmic opening and closing of mandible that is coordinated with tongue movements

71
Q

MASTICATION

Functions (2)

A
  1. Prepare food bolus for swallowing

2. Initiate digestive and metabolic activities

72
Q

Mechanical digestion – Reduce particle size (3)

A

Break up cells
Break up indigestible cellulose
Increase surface area/decrease particle size for mixing with digestive enzymes

73
Q

Mix food with saliva (serous and mucous) (4)

A

Chemical digestion (mainly carbohydrates)
Sufficient plasticity
Surface lubrication
Cohesive structure

74
Q
  1. Initiate digestive and metabolic activities (2)
A

Digestion of carbohydrates in mouth

Initiate reflexes to prepare digestive tract for incoming food

75
Q

Deglutition (Swallowing)

three stages

A
  1. Voluntary Stage
  2. Pharyngeal Stage
  3. Esophageal Stage
76
Q
  1. Voluntary Stage (3)
A

Initiate swallowing process
Bolus of food moved into pharynx by tongue
Stimulates epithelial swallowing receptor area

77
Q
  1. Pharyngeal Stage (5)
A

Involuntary
Mediated by swallowing center in brainstem
Soft palate pulled upward and closes off nasopharynx
Epiglottis closes off trachea (Respiration inhibited for < 2 sec.)
Upper Esophageal Sphincter (UES; Pharyngoesophageal Sphincter) relaxes

78
Q
  1. Esophageal Stage (2)
A

Coordinated muscle contractions to move bolus through esophagus into stomach (aborally).
≈ 10 sec.

79
Q

Esophageal Function:Sphincters and Peristalsis (3)

A
  1. Transport of solids and liquids from Pharynx to stomach
  2. Prevents air intake - UES
  3. Prevents reflux (stomach to esophagus) -LES
80
Q

Peristalsis =

A

wave of contraction that moves bolus through esophagus

81
Q

Primary Peristalsis-

A

continuation of peristaltic wave initiated during pharyngeal phase of swallowing (8-10 sec)

82
Q

Secondary Peristalsis- activated by

A

esophageal distension from retained food in esophagus

83
Q

secondary peristalsis

Function (2)

A

Clearing a bolus that was not wholly expelled by primary wave
Removing any gastric contents that reflux back into the lower esophagus

84
Q

Upper and lower esophageal sphincters

A

remain closed between swallows.

Both have tonic contractile properties.

85
Q

Upper esophageal sphincter relaxes during —.

A

swallow

86
Q

Lower esophageal sphincter relaxes as

A

peristaltic wave approaches.

87
Q

Gastro-Esophageal Reflux Disease (3)

A

Reflux of gastric contents into esophagus
Common and potentially disabling
Treated by inhibiting gastric acid secretion

Physiology (53 decks)

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