*Physiology 2 Flashcards

1
Q

Where are the parotid glands located?

A

Anterior to the ear below the zygomatic arch

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2
Q

What duct carries saliva from the parotid gland to the mouth and where does it connect with the mouth?

A

Duct of stensen

Enters mouth opposite second maxillary molar teeth

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3
Q

Where are the submandibular glands located?

A

Medial to the body of the mandible

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4
Q

What duct carried saliva from the submandibular glad to the mouth and where does it enter the mouth?

A

Duct of Wharton

Enters the mouth under the tongue by lingula frenulum via sublingual caruncula

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5
Q

Where is the sublingual gland located?

A

Medial to the submandibular glands

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6
Q

What duct arises from the sublingual glands and where does it connect to?

A

Ducts of Rivinus/ common Bartholin

Connects with Wharton’s duct at the sublingual caruncula

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7
Q

Are salivary glands exocrine or endocrine?

A

Exocrine (secrete into ducts)

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8
Q

What are the main parts of a salivary gland? (3)

A

External capsule
Septae separating lobes and lobules
Lobules composed of salivons (the functional unit of the gland)

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9
Q

What are the parts of the salivon? (3)

A

A secretory acinus
Intercalated duct
Striated duct

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10
Q

What do intercalated ducts combine to form?

A

Striated ducts

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11
Q

What do striated ducts combine to form?

A

Excretory ducts

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12
Q

What type of cells is the acinus of the salivon made up of?

A

Pyramidal-shaped secretory acinar cells which are either:

  • serous cells producing a water secretion rich in alpha-amylase
  • mucous cells producing a think mucous-rich secretion
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13
Q

What cells surround the acinus?

A

contractile myoepithelial cells

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14
Q

What is the name of the serous cells at the distal end of a mucous, tubuloalveolar secretory unit of certain salivary glands that secretes lysozyme?

A

Serous demilunes

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15
Q

What kind of epithelium lines the intercalated ducts?

A

Cuboidal epithelium

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16
Q

What kind of epithelium lines the striated ducts?

A

Columnar epithelium

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17
Q

What are the main functions of saliva? (5)

A

Lubrication
Protection (against bacteria and their metabolic products)
Digestion
Copious secretion prior to vomiting (emesis)
Facilitates suckling by infants

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18
Q

What 3 components of saliva buffers metabolic acids?

A

Bicarbonate
phosphate
mucus

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19
Q

What component of saliva helps to prevent demineralisation of tooth enamel?

A

High calcium salt

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20
Q

What coats the teeth reducing bacterial adherence?

A

Protein

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21
Q

What component of the saliva limits the availability of iron for bacteria requiring iron for growth?

A

Lactoferrin (chelates iron)

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22
Q

What in the saliva contributes to immunity against bacteria and viruses?

A

IgA

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23
Q

What 2 enzymes are present in saliva?

A

Alpha-amylase (ptyalin)

Lingual lipase

24
Q

What are the main electrolyte constituents of saliva? (7)

A

Na+, K+, Ca2+, Cl-, I-, PO4(2-) and HCO3-: present at lower concentration than plasma, apart from K+ and HCO3- which are found at higher concentrations

25
Q

What type of secretions does the parotid glands secrete? (main type of cell)

A

Serous cells produce a watery alpha-amylase rich solution = 25% of daily secretion

26
Q

What type of secretion does the submandibular glands secrete? (main type of cell)

A

Mixed serous and mucous cells produce a more viscous solution that the parotids = 70% of daily secretion

27
Q

What type of secretion dies the sublingual gland produce? (main cell type)

A

Mainly mucous cells = thick solution rich in mucous = 5% of total daily secretion

28
Q

Does HCO3- concentration in saliva (and therefore pH), increase or decrease with increasing rate of secretion?

A

Increase

29
Q

Does K+ concentration increase or decrease with rate of secretion?

A

Decrease

30
Q

What are the 2 stages involved in the formation of saliva?

A

Primary secretion by the acinar cells

Secondary modification by the duct cells

31
Q

What drives the primary secretion of fluid and electrolytes by the acinar cells?
How does this transport ions?

A

The basolateral Na+K+ATPase

Secondary active transport

32
Q

Summarise the movement of ions during primary secretion?

A

Cl- is transported into the cell via the Na+/K+/2Cl- (triple) transporter which raising the intracellular concentration of Cl- creating an electrochemical gradient driving Cl- efflux by facilitated diffusion through the apical membrane Ca2+ activated Cl- channels
Na+ and K+ diffuse into the duct to maintain electrical neutraloty via apical Ca2+ activated K+ channels and the paracellular route, respectively
H20 follows by osmosis

33
Q

Summarise the movement of ions during secondary modification?

A

Na+ and Cl- are removed from the primary secretion
K+ and HCO3- are added to the primary secretion
(driven by basolateral Na+/K+ ATPase

34
Q

What are the 2 categories of ways that secretion of saliva can be stimulated?
What part of the brain does each send afferent signals to?

A

Simple (unconditioned) eg. chemo-, mechano- receptors (nucleus tractus solitarius in medulla oblongata)
Acquired (conditioned) e.g. think, smell, etc. (cerebral cortex) - this causes efferent impulses via the parasympathetic nerves = stimulation of salivary glands (efferent impulses via salivary glands can also cause stimulation of salivary glands)

35
Q

What nerve supplies thesubmandibular and sublingual glands?

A

CN VII

36
Q

What nerve supplies the parotid gland?

A

CN IX

37
Q

What 2 branches of the nervous system stimulate secretion of saliva?

A

Sympathetic (during stressful times)
Parasympathetic (either by unconditioned or conditioned stimuli)
*each branch produces different secretions

38
Q

What type of salvia secretions does parasympathetic stimulation cause?

A

Large volume, watery, enzyme-rich

39
Q

What is release of parasympathetic saliva mediated by?

A

M1/ M3 muscarinic acetylcholine receptors and VIP

40
Q

What is release of sympathetic salvia mediated by?

A

Alpha and beta 1 adrenoceptors

41
Q

What type of saliva secretions does sympathetic stimulation cause?

A

Small volume, thick mucus-rich

42
Q

What extra smooth muscle layer is present in the stomach?

A

Oblique (beneath circular layer)

43
Q

What nerve causes the stomach to relax receptively?

A

Vagus nerve

44
Q

What digestion is initiated in the stomach?

A

Protein digestion (HCl and pepsin)

45
Q

What is produced in the stomach?

A

Chyme (food + gastric secretions)

46
Q

What is the fundus normally filled with?

A

Gas

47
Q

What are the rugae of the stomach?

A

series of ridges produced by folding of the wall of an organ.

48
Q

What happens to the thickness of the stomach wall as you move from the fundus to the antrum?

A

It increases (therefore so does the mechanical activity of the stomach)

49
Q

What type of chyme can pass through the pyloric sphincter?

A

Semi-liquid chyme

50
Q

State of the pyloric sphincter during mixing?

A

Closed

51
Q

What are the 2 broad categories of factors that influence the strength of antral contraction and therefore movement of chyme through the stomach?

A

Gastric factors

Duodenal factors

52
Q

In terms of chyme, what is the rate of emptying proportional to?

A

Volume and consistency of chyme in the stomach

53
Q

What does a large volume in the stomach cause? (4) - gastric factors that cause emptying of stomach

A

Motility due to stretch of smooth muscle
Activity of intrinsic nerve plexuses
Vagus nerve activity
Gastrin release

54
Q

How can the duodenum delay emptying of the stomach?

A
Neuronal response (enterogastric reflex)
Hormonal response (release of enterogastrones)
55
Q

What effect does the enterogastric reflex have?

A

Decreases antral peristaltic activity through signals from intrinsic nerve plexuses and the ANS

56
Q

What do the enterogastrones do?

A

Inhibit stomach contraction

57
Q

What are some examples of stimuli in the duodenum that drive the neuronal and hormonal response = not ready to receive chyme?

A

Fat
Acid (time is required for neutralisation by bicarbonate secreted from the pancreas)
Hypertonicity
Distension