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nuero > pancrease > Flashcards

pancrease Flashcards

1
Q

descirbe the sorounding structures of the pancrease

A

look up on google

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2
Q

where is teh pancrease

A

a long, flat gland that lies horizontally behind your stomach. It has a role in digestion and in regulating the level of sugar in your blood.

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3
Q

draw a ct scan of the pancrease

A

draw

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4
Q

define endocrine

A

: Secretion into the blood stream to have effect on distant target organ (Autocrine/Paracrine) - Ductless Glands

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5
Q

defien autocrine

A

: Secretion into a duct to have direct local effect

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6
Q

Q. What are the main endocrine secretions of the pancreas & their actions?

A

Insulin: anabolic hormone
promotes glucose transport into cells & storage as glycogen
↓ blood glucose
promotes protein synthesis & lipogenesis
Glucagon: ↑s gluconeogenesis & glycogenolysis (↑s blood glucose)
Somatostatin: “Endocrine cyanide”

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7
Q

what makes up the endocrine of the pancrease

A

Islets of Langerhans

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8
Q

what is secreated by the islets of langerham

A

Secrete hormones into blood - Insulin & Glucagon (also Somatostatin and Pancreatic Polypeptide)

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9
Q

what are the function of each of the hormones

A

Regulation of blood glucose, metabolism & growth effects - (Endocrine course)

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10
Q

what is the exocrine function of the gland

A

Secretes pancreatic juice

Digestive function

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11
Q

where is pancreatic juice secreated

A

into duodenum via MPD/sphincter of Oddi/ampulla

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12
Q

what are acinini in the pancrease

A

Ducts

Acini are grape-like clusters of secretory units

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13
Q

what is teh function of the acinar cells

A

Acinar cells secrete pro-enzymes into ducts

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14
Q

what are islets in the pancrease

A

Formation of acini & islets from ducts in various stages of development

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15
Q

what do islets differntiate into

A

α- and β-cells secreting into blood

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16
Q

where are the islets higher in head or tail

A

tail

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17
Q

what is the compisition of teh islets

A

α-cells
β-cells
δ-cells
Acini

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18
Q

what is the function of the a cells

A

form about 15-20% of islet tissue and secrete glucagon

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19
Q

b cells

A

form about 60-70% of islet tissue and secrete insulin

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20
Q

delta

A

form about 5-10% of islet tissue and secrete somatostatin

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21
Q

what is another function of the islets

A

The islets are highly vascular, ensuring that all endocrine cells have close access to a site for secretion

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22
Q

how are acinar cells illustrated on a microscope sample

A

exocrine pancreatic cells

Large with apical secretion granules
big circle in them containg other smaller circles

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23
Q

how do ducts look like

A

Small & pale

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24
Q

how many components are the to the pancreatic juice

A

2

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25
Q

what are they

A

↓ (low) vol, viscous, enzyme-rich

↑ (high) vol, watery, HCO3- rich -

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26
Q

what secraetes the high vol, watery, HCO3- rich -

A

Duct & Centroacinar cells

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27
Q

what secreates the low vol, viscous, enzyme-rich

A

Acinar cells

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28
Q

so what produces teh bicarbonate secreation

A

duct & centroacinar cells

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29
Q

what does the p juice contain

A

↑ bicarbonate
~ 120 mM (mmol/L) - (plasma ~25 mM)
pH 7.5-8.0

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30
Q

what are the function of the pancreatic juice (x4)

A

Neutralises acid chyme from stomach
prevents damage to duodenal mucosa
Raises pH to optimum range for pancreatic enzymes to work

Washes low volume enzyme secretion out of pancreas into duodenum

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31
Q

what occurs when the deodenal ph goes from 5 to 3

A

linear ↑more in pancreatic HCO3- secretion

then platueas at ph of 3

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32
Q

what occurs when the deodenal ph is less than 3

A

→ not much more high in HCO3- secretion

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33
Q

Q. Why does HCO3- secretion stop when pH is still acid?

A

Bile also contains HCO3- and helps neutralise acid chyme (liver functions lecture).
Brunners glands secrete alkaline fluid (Small intestine lecture

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34
Q

what is the production of hco3- cataylsed by

when c02 enters the pancraetic duct cell combining with water to form h+ and hc03-

A

carbonic anhydrase

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35
Q

where does sodium move to and from

A

blood to lumen

36
Q

how dies it move

A

down gradient via paracellular (“tight”) junctions

37
Q

how and where does water move

A

follows h20 from blood to lumen

through paracellular junctions

38
Q

how is the hco3- able to move out of the pancreatic duct cell to pancreatic duct cell

A

Cl-/HCO3- exchange at lumen (anion exchanger [AE])

39
Q

How can the H+ movw out of teh PDC to the blood

A

Na+/H+ exchange at basolateral membrane into bloodstream (sodium-hydrogen exchanger (antiporter) type 1 [NHE-1])

40
Q

what causes the exchanges to occur

A

High ElectroChemical gradient (blood) Na+ compared to IC (duct cell)
High Cl- in lumen compared to IC (duct cell)
(for that you must mantain the gradient)

41
Q

what are the 2 exchanges

A

Cl-/HCO3- exchange at lumen (anion exchanger [AE])

Na+/H+ exchange at basolateral membrane into bloodstream (sodium-hydrogen exchanger (antiporter) type 1 [NHE-1])

42
Q

How is the sodium gradient mantained

A

Na+ gradient into cell from blood maintained by Na+/K+ exchange pump

43
Q

is it an active or a passive process

A

Uses ATP - Primary active transport

44
Q

where do the k+ and cl- move back to

A

k+ ->returns to blood

Cl- ->returns to lumen

45
Q

how is ch- returned to blood

A

via Cl-channel (cystic fibrosis transmembrane conductance regulator [CFTR]) doesn’t work properly with people with cf

46
Q

and how is k+ returnes to blood

A

via K+-channel

47
Q

what is the reaction to produxe pancreatic juice

A

H2O + CO2 H2CO3 H+ + HCO3-

Same reaction in gastric parietal cells (acid) and pancreatic duct cells (alkaline)

48
Q

what is the relative ph of the gastric venous blood

A

H+ secreated into gastric juice

HCO3- secreated into blood

Thus

Gastric venous blood is alkaline

49
Q

Ph of Pancreatic blood is

A

HCO3- secreted into pancreatic juice

H+ secreated into blood

Pancreatic venous blood is acidic

50
Q

what do acinar cell enzyme secreations do and what enzymes

A

fat (lipases)
protein (proteases)
carbohydrates (amylase)

51
Q

how are the enzymes

A

Zymogens = pro-enzymes

52
Q

where are they stored and sythesised

A

→ synthesised & stored in zymogen granules

53
Q

Q. What might be the problem for an organ making a cocktail of digestive enzymes?

A

You could start digesting yourself so you need saftey mechanisms

Proteases are released as inactive pro-enzymes
protects acini & ducts from auto-digestion

Pancreas also contains a trypsin inhibitor to prevent trypsin activation

Enzymes only activated in duodenum

Blockage of MPD may overload protection -> auto-digestion (= acute pancreatitis)

54
Q

what is the Duodenal mucosa secretes an enzyme and where is it produced

A

Enterokinase (enteropeptidase)

brush border

55
Q

what does it do

A

converts trypsinogen -> trypsin.

56
Q

what is the function of trypsin

A

Trypsin then converts all other proteolytic & some lipolytic enzymes into active form

57
Q

are the pancreatic secraetions modifiable

A

Pancreatic secretions adapt to diet:

e.g. ↑ protein, ↓ carbs → ↑s proportion of proteases & ↓ proportion of amylases

58
Q

what can a lack of pancreatic enzyme cause

A 
Pancreatic enzymes (+ bile) essential for normal digestion of a meal: 
 Lack of these can → malnutrition even if dietary input is OK.
(unlike salivary, gastric enzymes)
59
Q

Q. Anti-obesity drug Orlistat inhibits pancreatic lipases – what side effects might you expect?

A

more increased faecal fat
occurs when pancreatic lipase secretion ↓ed
e.g. cystic fibrosis, chronic pancreatitis, Orlistat (↓s intestinal fat absorption)

60
Q

what are the 3 stages to the pancreatic juice secreation

A

Cephalic phase
Gastric phase
Intestinal phase

61
Q

what is the cephalic phase

A

Reflex response to sight/smell/taste of food
Enzyme-rich component only.
Low volume - “mobilises” enzymes
secreation of enzymw rich component from acini only

62
Q

what is the gastric phase

A

Stimulation of pancreatic secretion originating from food arriving in the stomach
Same mechanisms involved as for cephalic phase

63
Q

what is the intestinal phase

A

Hormonally mediated when gastric chyme enters duodenum.
BOTH components of pancreatic juice stimulated
enzymes & HCO3- juice flows into duodenum

64
Q

how is Pancreatic juice enzyme secretion controlled in acini by:

A
  1. Vagus nerve –
    Cholinergic
    Vagal stimulation of enzyme secretion (& communicates information from gut to brain)
  2. Cholecystokinin (CCK) (Ca2+/PLC)
65
Q

Pancreatic juice bicarbonate secretion controlled in duct & centroacinar cells by:

A

Secretin (cAMP)

66
Q

how do the abdominal accesory organ grow

A

as foregut outgrowtha

67
Q

does everyone have a accessory pancreatic duct

A

no

68
Q

where are the transverse colon and stomach to the pancrease

A

anterior

69
Q

what are the parts of the pancrease

A

head neck body tail

70
Q

where does the pancrease fit

A

head of pancrease fits in deodum

71
Q

what do the pancreatic acinus sorround

A

duct

72
Q

what are between the pancreatic acinar cells

A

cellular canaciculi

73
Q

how is enzyme secreation controllled in acini

A

vagus via ach stimulates pancrease to produce pancreatic enzymes

74
Q

how is CCK controlled (where realased as well)

stimulation

A

secreated from duodenal I cells

stimulated by fatty acid and amino acids in the lumen of the duodenum

75
Q

how is CCK inhibited

A

via trypsin

76
Q

is the acinar fluid more or less concentrated in ions that the plasma

A

acinar is isotonic so same

77
Q

what stimulates release of acinar fluid and protiens it contains

A

CCK

78
Q

what does secretin do

A

stimulates secretion of H2O & HCO3- from cells lining extralobular ducts.

79
Q

why

A

in response for absorption in CL-

80
Q

what is richer is in hco3- out of acinar fluid or secretin stimulated secreation

A

Secretin-stimulated secretion is richer in HCO3−cf acinar secretion because of Cl−/HCO3−exchange

81
Q

how is hco3- secreation controlled

A

secretin

negative feedback loop in response to low luminal ph in duodenum

82
Q

what happens

A

low ph in duodenem
stimulates s cells
secretin released
pancreatic and ductal hco3- secreation

83
Q

how much does hco3- get secreated when cck acts alone

A

no effect alone
same with vagus nerve
secretin has a minumun affect alone

84
Q

what produces the biggest affect

A

both cck and secretin

85
Q

how does secretin effect enzyme secreation

A

no effect

86
Q

outlines what happens when you have a meal

A

Food mixed, digested in stomach, pH 2
Chyme squirted into duodenum
H+ ions in duodenum -> ^ secretin -> ^pancreatic juice
+ bile & Brunner’s gland secretions

both causing ^s pH to neutral/alkaline.

Peptides & fat in duodenum cause sharp ^ in CCK & vagal nerve stimulation
-> stimulates pancreatic enzyme release
Peaks by 30 mins, continues until stomach empty.

CCK potentiates effects of secretin on aqueous component
Necessary as most of duodenum not at low pH

nuero (36 decks)

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