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Principles of pharmacology and physiology > Supporting Digestion > Flashcards

Supporting Digestion Flashcards

1
Q

Describe the composition of saliva and their function

A

Mucus
Enzymes (mainly amylase)
Antibacterial enzymes (lysozyme that prevent dental decay)
Proteins (lactoferrin)
Antibodies
Inorganic ions (teeth, mineralisation/repair)
Proteins to coat teeth, protection

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2
Q

Functions of saliva

A 
Lubricates
Moistens
Begins digestion (a amylase, lipase)
Antiseptic (IgA and lysozyme)
Teeth maintenance and repair
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3
Q

How much saliva do we produce each day

A

600-1500ml/day

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4
Q

Function of the salivary glands

Types of salivary glands

A

Secrete in response to physical, chemical, psychological stimuli via parasympathetic

Parotid
Sublingual
Submandibular

Buffalo
Labial
Lingual
Palatine

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5
Q

Describe the composition of parotid glands

A

Serous cells, thin watery secretion
Enzyme and antibody rich

Stains well with H and E

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6
Q

Describe the composition of sublingual cells

A

Mucous cells, viscous secretion

Does not stain well

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7
Q

Describe the composition of submandibular glands

A

Has both serous, mucous secretory cells

Only the serous cells stain well

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8
Q

Describe the composition of a serous acinar cell

A 
Well stained granules
Many
-Secretory granules 
-Golgi
-RER
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9
Q

Describe the composition of a mucous acinar cell

A

Poorly stained granules

Many
-Mucus product granules

-Irregularly basally located nuclei

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10
Q

Describe what serous demilunes are

A

May be a fixation artefact

Conventional fixation leads to serous demilune shape between mucus cells

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11
Q

Describe the composition of intercalated ducts

A

Lined by cuboidal epithelium

Longest in parotid, join within lobules to form striated ducts

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12
Q

Describe the composition of striated ducts

A

Lined by tall columnar epithelium ,large nuclei towards apex
Basal cytoplasm has interdigitations of cytoplasmic processes and mitochondrial columns

Na+ pumps reabsorption Na+, Cl-, replaced with K+, HCO3-,
Saliva becomes more hypotonic here

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13
Q

Describe the composition of the interlobular duct

A

Pseudostratified columnar epithelium

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14
Q

Describe the composition of the lobular duct

A

Stratified bilayer of cuboidal/columnar

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15
Q

How are secretions from the acinar stimulated

A 
Parasympathetic, sympathetic stimulations cause 
-Proteins
-Enzymes
-NaCl
-H20 
To be secreted from the acinar cells

Isoosmotic saliva passes through the intercalated duct
Hypotonic saliva formed in the striated duct
-NaCl removed
-K+, HCO3- secreted into the duct

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16
Q

Describe the structure of the glands in the pancreas

A

Compound tubular gland in concavity of duodenum

Combined exocrine and endocrine gland (no digestive function)

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17
Q

Describe the structure of the endocrine glands in the pancreas

A

Endocrine cells have an apical nucleus, basal secretory vesicles
Release hormones into fenestrated capillaries in the Islets of Langerhans

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18
Q

Describe the cellular composition of the Islet of Langerhans

A 
A cells, (20%) glucagon
B cells (70%) insulin
S cells (5-10%) somatostatin
PP cells (1-2%) pancreatic polypeptide

Other minor cells secrete VIP, P, motilin, seretonin

19
Q

Describe the structure and composition of the exocrine pancreas

A

Acinar secretory cells with centroacinar cells (unique to pancreas)
Lumen of acinus leads to intercalated duct lined with simple cuboidal epithelium
Non striated ducts converge => interlobular ducts lined by stratified cuboidal epithelium

20
Q

Describe the structure of the acinar cells and the centroacinar cell

A

Acinar cell has a basally located nucleus and apical secretory vesicles
Centroacinar cells line the lumen of the duct

21
Q

What is the function of the exocrine pancreas acinar

A

Secrete enzymes
Pyramidal cells with round basally located nuclei, basophils cytoplasm, well developed RER

Apices packed with eosinophilia secretory zymogen granules
Released into lumen, merocrine (CCK response from I cells)

22
Q

Function of the centroacinar cells

A

Water and HCO3- secretions
Pale nuclei, sparse pale cytoplasm
In center of acini
Form terminal lining of intercalated ducts

23
Q

Describe the composition of pancreatic juice (1L/day)

A

Apical area of acinar cells contains Golgi and zymogen granules with around 20 different enzymes/precursors
Rich in HCO3-, neutralise acidic chyme
Duodenal lining synthesises enteropeptidase, activates trypsinogen => trypsin

24
Q

Describe the composition of the intercalated ducts in the the exocrine pancreas

A

Lined by cuboidal epithelium

25
Q

How are pancreatic secretions stimulated

A

Parasympathetically stimulated
Acidic chyme causes CCK and secretin to be released into the blood

CCK causes secretory zymogen granules to be released by the acinar cells
Secretin causes HCO3- to be secreted from the ductal cells

26
Q

What are the main differences between the pancreatic acinar and the parotid acinar

A

Parotid

  • Striated ducts
  • No centroacinar cells
  • No Islets of Langerhans

Pancreas

  • No striated ducts
  • Centroacinar cells
  • Islets of Langerhans
27
Q

What are the main functions of the liver

A 
Protein metabolism
Carbohydrate metabolism
Fat metabolism
Storage
Detoxification
Secretion
28
Q

Describe the functions of the liver

Protein metabolism

A

Non essential AA synthesis

produce plasma proteins (albumin, clotting factors, lipoprotein proteins, Fe, Cu transport proteins)

29
Q

Describe the function of the liver

Carbohydrate metabolism

A

Carbs and protein => FA and TAGS

Regulate [blood glucose]

30
Q

Describe the function of the liver

Fat metabolism

A

Cholesterol, phospholipids, plasma lipoprotein synthesis

31
Q

Describe the function of the liver

Storage

A

Fe
Vitamins
Glycogen

32
Q

Describe the function of the liver

Detoxification

A

Of metabolic waste products
Deamination of AA => NH3 => urea => kidneys
Of steroid hormones, lipid soluble drugs
Metabolism of alcohol => acetalaldehyde => acetate

33
Q

Describe the function of the liver

Secretion

A

Synthesis, secretion of bile

34
Q

Describe the liver blood supply

A

Hepatic artery, hepatic portal vein
HPV brings substances absorbed by GI => liver
HA, oxygenated blood
Blood enters sinusoids of lobules, exposed to hepatocytes over LSA
Central vein collects blood, coalesce to => R and L HV => IVC

35
Q

What is the portal triad

A

HPV
HA
BD

36
Q

Describe the structure of the structural liver lobule

A

Veins surrounded by hepatocytes
Lobules surrounded by connective tissue
Portal tract forms when CT converges
Sinusoids flow towards central vein

Bile flows away from the central vein, into hepatic duct

37
Q

Describe the structure of the liver sinusoids

A 
Hepatocytes form sheets with at least 1 surface facing a sinusoid
Sinusoid walls (fenestrated epithelium) with Space of Disse between hepatocytes and endothelial sinusoid cells

Space of Disse contains hepatocytes microvilli
Macrophages (Kupffer cells) in inner sinusoid walls
Stellate cells produce ECM

38
Q

How is bile synthesised

A

In liver, stored and concentrated in gall bladder

Synthesised from cholesterol, acts as an emulsifying agent in gut, facilitated fat, vitamin absorption across mucosa
Bile salts absorbed in terminal port of ileum, returned to liver via portal system
Bile pigments breakdown products of worn out blood cells, destroyed by macrophages of spleen/Kupffer cells

39
Q

Describe the structure of the liver acinus

A

Roughly hexagonal in shape, each point has a bundle of sinusoids and a bile duct
Surround a central vein

Z1, most oxygenated, nutrient rich, closest to blood supply
-Specialised for oxidative functions (gluconeogenesis, B oxidation, cholesterol synthesis)

Z2, intermediate, O2, nutrient depleted

Z3, Specialised for glycolysis, lipogenesis, cytochrome drug detoxification

40
Q

Describe what happens to the liver in a paracetamol overdose

A

Extensive damage around central vein, denatured proteins take up more eosin

Hepatocytes around portal trial stain less, accumulate fat
Loss of liver architecture => RBC infiltration between cells

Z3, most sensitive to quinone produced by paracetamol

41
Q

Describe what happens to the liver in cirrhosis from chronic Hep B

A

Extensive fibrosis of portal triad, lobules
Architecture of lobules disrupted
Lots of inflammatory cells

42
Q

Describe what happens to the liver in cirrhosis causes by alcohol

A

Extensive fibrosis from Stellate cells
Architecture of lobules severely disrupted
Hepatocytes restricted to small regenerative nodules

43
Q

Describe the composition and function of the gall bladder

A

Muscular sac with simple tall columnar epithelium
Epithelial have irregular microvilli at luminal surface, basal nuclei
Loose submucosa rich in elastin, blood vessels, lymphatics

Bile resevoir
Conc bile from NaCl pumped from basolateral border => osmotic gradient
This displaces the basolateral surface causing splits between cells
Water enter lymphatics in lamina propria

44
Q

How does CCK cause bile release

A

CCK produced by I cells in duodenum in response to lipid
Causes smooth gall bladder muscle to contract
Bile discharges => duodenum via cystic duct and common bile duct controlled by major duodenal papilla

Emulsifying agent in gut, faciliates fat, vitamin absorption across gut mucosa

Principles of pharmacology and physiology (25 decks)

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