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Physio Exam 4 (Ana) > Lecture 55 > Flashcards

Lecture 55 Flashcards

1
Q

What is the role of saliva in initial digestion

A

Starts the process for starches & lipids for some species

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2
Q

What two enzymes in salvia help start the process of digesting starches & lipids

A

amylase & lipase

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3
Q

What are the functions of saliva

A
  • Initial digestion
  • Dilution & buffering
  • lubrication
  • oral hygiene
  • evaporative cooling in dogs
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4
Q

How does saliva help with lubrication

A

Works with mucus to help form a bolus for digestion

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5
Q

How does saliva help with oral hygiene

A

Flushes the oral cavity of food debris & has lysozymes in saliva that lyse bacteria

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6
Q

What is the pH of dog saliva

A

~ 8.5

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7
Q

Why is the pH of dog’s saliva higher than other animals & what does a high pH make them susceptible to

A
  • Because of the compounds secreted in their saliva
  • makes them susceptible to gengivitis b/c of more calculus
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8
Q

What are the major salivary glands

A

Parotid glands
submandibular glands
sublingual glands
zygomatic glands (also called dorsal buccal glands)

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9
Q

Which gland is defined by having “serous cells & aqueous fluid that has water, ions, and various enzymes”

A

Parotid glands

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10
Q

Which gland is defined as “mixed glands with serous & mucous cells (that have mucinglyco proteins that make the mucus thicker)”

A

Sublingual & submandibular glands

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11
Q

What is the “grape” of the slaivary gland

A

An ancinus lined with acinar cells

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12
Q

Why are acinar cells important

A

The produce initial saliva that consist of water, ions, enzymes, & mucus

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13
Q

Initial saliva passes through the _________ duct then goes to the ______ duct

A

intercalated; striated

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14
Q

What cells line the striated duct & are used to modify saliva by altering ion concentration

A

Ductal cells

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15
Q

What does neural stimulation do to the myoepithelial cells

A

It causes them to contract & eject saliva

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16
Q

What type of ANS neural stimulation usually dominates the salivary glands [PNS or SNS]

A

PNS

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17
Q

T/F: acinar & ductal cells BOTH have PNS & SNS innervation

A

T

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18
Q

T/F: Salivary glands have LOW blood flow

A

F

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19
Q

What happens to blood flow then saliva production is stimulated [decrease or increase]

A

Increases

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20
Q

Why is saliva hypotonic compared to plasma

A

B/c ductal cells are impermeable to water (they don’t reabsorb water)

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21
Q

What organic components can acinar cells secrete

A
  • alpha amylase
  • Lingual lipase
  • mucin glycoporoteins
  • IgA
  • Kallikrein
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22
Q

What species is alpha amylase found in

A

Pigs and humans

23
Q

What does Kallikrein do

A

Increases BF especially during increased saliva production

24
Q

Definition: “an enzyme that helps to regulate vasodilation association with secretions”

A

Kallikrein

25
Q

Saliva has a slight increase in _______ but a decrease in _________ compared to plasma

A

K+ & Bicarb; Na+ & Cl-

26
Q

What are the two steps for forming saliva

A
  1. Formation of Isotonic solution by acinar cels
  2. Modification of the solution by ductal cells that cause saliva to be hypotonic
27
Q

Where are the transporters used in modification of saliva found

A

On the luminal membrane & basolateral membrane

28
Q

Name the luminal membrane transporters

A
  • Na+/H+ exchange
  • Cl-/HCO3- exchange
  • H+/K+ exchange
29
Q

Name the basolateral membrane transporters

A
  • Na+/K+ ATPase
  • Cl- channels
30
Q

Na+ & Cl- are absorbed into the [blood/saliva] while K+ & HCO3 are secreted into [blood/saliva]

A

Blood; saliva

31
Q

At high flow rates (4mL/min), final saliva resembles ______

A

plasma

32
Q

At low flow rates (< 1 mL/min) final saliva is [hypertonic/hypotonic]

A

Hypotonic

33
Q

What does the final compistion of saliva depend on

A

The amount of time the saliva is in contact with the ductal cells (high flow rates out of the ductual cells means that there is less contact time with the ductal cells)

34
Q

What happens to HCO3 concentrations @ low flow rates & high flow rates

A

Low flow rates - Concentration is lowest of all solutes
High flow rates - Highest concentration of all solutes (secretion is selectively stimulated by PNS)

35
Q

what are the main features of saliva regulation

A
  • It is exclusively under neural control (no hormonal control)
  • Secretion is stimulated by both PNS & SNS that act on muscarinic receptors on acinary & deuctal cells (this is to increase volume and the amount of enzymes in saliva)
36
Q

What nerves carry PNS innervation for salive & what do the PNS postganglionic neurons release

A

Facial (CN VII) & glossopharyngeal (CN IX)
Postganglionic neurons release Ach

37
Q

Where does SNS innervation originate, where does it synapse, & what does it postganlionic neurons release & act on

A
  • Origin - T1 & T3
  • Synapse on - superior cervical ganglion
  • Postganglionic neurons - release NE and act on beta adrenergic receptors to increase secretion volue & enzymes
38
Q

What are the components of gastric juice

A
  • HCl
  • Pepsinogen
  • Intrinsic factor
  • Mucus
39
Q

Why is pepsinogen important in gastric juices

A

For initiating Protein digestion

40
Q

Why is intrinsic factor important in gastric juices

A

For absorption of vitamin B12 in the ileum

41
Q

Why is mucus important in gastric juices

A

To protect the gastric mucosa from HCl
Involved in lubrication

42
Q

What do the parts of the oxyntic glands found in the body of the stomach do/secrete (pits, mucous neck cells, parietal cells, & chief cells)

A
  • Pits - openings that empty products into the stomach lumen via ducts & is lined with epithelial cells
  • Mucous neck cells - secrete mucus
  • Parietal cells - secretes HCl and intrinsic factor
  • Chief cells - makes pepsinogen (not activated yet)
43
Q

Definition: “A protease that chops proteins, and is not activated until it is needs”

A

Pepsinogen

44
Q

What do the parts of the pyloric glands of the antrum of the stomach do/secrete (pits, g cells, mucous neck cells)

A

Pits - do the same thing as oxyntic glands they are just deeper
G cells - secrete gastrin into blood circulation
Mucous neck cells - secrete mucous, bicarb, & pepsinogen

45
Q

Describe the what initiates HCl secretion, what transporters the luminal apical membrane & basolateral membrane have, & what these cells contain

A
  • Caused by the parietal cells to make the pH drop to a 1 or 2.The drop in pH activates pepsinogen (and turns pepsinogen into pepsin)
  • Luminal apical membrane has H/K ATPase Cl channels
  • The basolateral membrane has Na/K ATPase & Cl/HCO3 exchangers
  • These cells contain carbonic anhydrase
46
Q

List the steps of HCl secretion & state the net product of HCl and HCO3

A
  1. CO2 combines with H2O to form H2CO3 which dissociates into H+ and HCO2 (H+ goes to the lumen of the stomach via H/K ATPase while HCO3 is absorbed into the blood via HCO3/Cl exchanger)
  2. Cl- follows H+ into the lumen by diffusing through Cl- channels
  3. The absorbed HCO3 is responsible for an “alkaline tide” in the gastric venous blood after a meal (the bicarb in the tide is eventually secreted back to the GI tract via pancreatic secretion)
  4. Results = Net secretion of HCl & Net absorption of HCO3
47
Q

What substances stimulate H+ secretion

A

Histamine (paracrine)
Ach (neurocrine)
Gastrin (hormone)

48
Q

Histamine (where it is released, what it binds to, its second messengers, & an inhibitor)

A

Released from ECL cells in the gastric mucosa
Binds to H2 receptors on the parietal cells
uses cAMP as a second messenger
Cimetidine will block H2 receptors which will block histamines action on parietal cells

49
Q

Ach (where it is released, what it binds to, its second messengers, an inhibitor, & what can it stimulate)

A

Released from the vagus nerves innervating the gastric mucosa
Binds to muscarinic receptors in the parietal cells
IP3 DAG/Ca are its second messengers
Atropine will block the muscarinic receptors on the parietal cells
Can also stimulate ECL cells to release histamine

50
Q

Gastrin (where it is secreted, what it binds to, its second messengers, an inhibitor, & what can it stimulate)

A

Secreted by G cells in the stomach antrum
Binds to CCKB receptors on parietal cells
IP3 DAG/Ca is its second messengers
Can also stimulate Ecl cells to release histamine

51
Q

Definition: “the sum of 2 stimuli causes a greater response than the indiv responses alone”

A

potentiation

52
Q

What interactions are seen between histamine and Ach (or gastrin)

A

A potentiation interaction (gives the strongest response to stimulate H+) because they use different receptors
Ach & gastrin also independently stimulate histamine release

53
Q

Definition: “Inhibits transporters on parietal cells no matter the stimulus, mostly blocks secretion”

A

Omperazole

Physio Exam 4 (Ana) (14 decks)

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