Histology Of Salivary/digestive Glands

Front 1

give an example of:
- mucous secretion
- serous secretion
- mixed secretion

Back 1

- esophageal [mucin]. Gen. spherical.
- pancreas [protein/enzyme: watery] Gen. tubular
- salivary: serous demilunes [mucous acini capped by serous cells] [artifact]

Front 2

Structure of exocrine gland: [3]

Back 2

1. myoepithelial cell: contractile cell between gland cell + basal lamina of epithelium. squeeze secretory unit from centre to acinus
2. acinus→intercalated duct→intralobular→interlobular→lobar→main
3. CT/fibroblast/lymphocytes between lobules

Front 3

Describe structure of salivary glands [2]
1. Major
- give an example[3]
2. Minor
- give an example[5]

Back 3

- compound tubuloacinar
- basic secretory unit: acinus [serous, mucous, mixed]

1. Major salivary glands: paired gland, long duct emptying into oral cavity
*surround by capsule of mod. dense CT
*CT septa divide glands into lobes/lobules: contains larger BV + excretory ducts
- Parotid [serous]: below+in front of ear
- submandibular [mixed]: under floor of mouth
- Sublingual [mucous]: floor of mouth ant. to submandibular gland

2. Minor salivary gland: submucos of diff. parts of oral cavity

- buccal, lingual, labial, molar, palatine

Front 4

Innervation of salivary gland [2]

Back 4

1. Sympathetic (Cervical symp. chain)
- slow rate of secretion
- high in protein/consistency (thick saliva)

2. Parasympathetic
- copious secretion
- low consistency, more watery

Front 5

Ducts of salivary gland
1. [2]
2. [4]
3. [3]

Back 5

1. Intercalated: intralobular, from acinus
- prominent in watery serous gland [parotid]
- difficult/short in mucous secretory [sublingual]

2. Striated:
- intralobular [in the parenchyma of gland]
- basal infolding + long. arranged mitochondria
- absorption (Na+) & secretion (K+, HCO3-)
- striated duct ø exceeds secretory acinus ø

*1&2 modify serous by absorbing/secreting: ax w. serous, not mucous, acini*

3. Excretory
- in interlobular + interlobar CT, empty → oral cavity
- small excretory duct (simple cuboidal): change to pseudostrat col. or strat cuboidal/squamous as ↑size
- Stensen's (parotid) + Wharton's (submandibular) travel in CT of face & neck respectivley

Front 6

describe structure of parotid glands [3]

Back 6

- *Lots of adipose tissue*
- completely serous
- largest among major salivary gland, paired

Front 7

describe structure of submandibular glands [2]

Back 7

- large, paired
- mixed/predominantly serous in human

Front 8

describe structure of sublingual glands [3]

Back 8

- smallest among major salivary glands
- some of mucous acini ax w. serous demilune
- mixed, mostly mucus-secreting in humans

Front 9

saliva
- how much is secreted per day [1]
- composition [3]

Back 9

- 1200 mL produced

- water,
- various proteins, electrolytes:
- principle enzymes: lysozymes, a-amylase

Front 10

Functions of saliva
- digestion [4]
- protection [5]

Back 10

Digestive:
- aid swallowing
- dissolve food → can be chemically tasted
- buffering (high conc. of bicarbonate ions)
- digest carbohydrates (a-amylase)

Protective:
- moisten oral mucosa
- control bacteria flora in oral cavity [lysozyme]
- tooth development/maintenance (Ca, phosphate)
- IgA [plasma cells in CT surround secretory acini]
- Dimeric receptor for IgA: secretory glycoprotein inserted on basal membrane
[receptor-mediated endocytosis→acini cells→apical membrane→secreted]

Front 11

Structure of pancreas [3]

Back 11

- elongate gland: head, body, tail

- Exocrine:
*synthesize/secrete digestive enzyme into duodenum
*proteolytic peptidase (trypsin, chymotrypsin), a-amlyase, lipase, nuclease

- Endocrine (islets of Langerhans)
*insulin, glucagon

Front 12

Structure of exocrine pancreas [1]

- divided into [2]

Back 12

- serous glands:
1. Secretory unit
2. Ductal system

Front 13

Secretory unit structure [4]

Back 13

1. acinar or tubuloacinar

2. basophilia in basal cytoplasm:
*rER, free ribosome [high level of protein synthesis]

3. acidophilic zymogen granules, apical cytoplasm
*proenzymes (Trypsinogen, chymotrypsinogen), activated only in SI by enterokinase at microvilli
- trypsinogen→trypsin→convert other inactive enzyme & digest protein

4. well-developed Golgi apparatus

Front 14

Ductal system of exocrine system [4]
- intercalated duct [2]

Back 14

1. Intercalated duct (Squamous) →
intralobular duct (cuboidal, no striated duct) →
Main pancreatic duct (long axis of pancreas) →
Accessory pancreatic duct (head of pancreas)

2. Intercalated duct start in acinus
- Centroacinar cell: duct cell within acinus [pale-stain]
- Intercalated duct: add HCO3-, H2O into exocrine s.

Front 15

What controls pancreatic exocrine secretion [3]

Back 15

1. Hormone: secretin, CCK [stim by acidic chyme in duodenum]

2. PSNS: activity of acinar + centroacinar cells

3. SNS: regulate pancreatic blood flow

Front 16

Function of exocrine pancreas

Back 16

Secrete pancreatic juice w. digestive enzyme for:
- Protein: trypsin, chymotrypsin
- Carbohydrate: a-amylase, maltase
- Lipid: lipase

Front 17

Endocrine pancreas

Back 17

- regulate BG levels

Islets of Langerhan (1-2% pancreas)
1. A (alpha, 15-20%; glucagon)
2. B (beta, 70%: insulin)
3. D (delta, 5-10%, somatostatin)

4. PP (pancreatic polypeptide)
5. D-1 (VIP)
6. EC (secretin, motilin, substance P)

Front 18

STructure of liver [3]

Back 18

- largest gland in body (1.5 kg, 2.5% body weight)
- endoderm evagination from wall of foregut
- hepatocyte: cellular cords

Front 19

FUncitons of liver [9]

Back 19

1. Protein synthesis (albumin, lipoprotein, glycoprotein, prothrombin, nonimmune a & b-globulin)
2. Vit A/K: Uptake/store/distribute nutrient (Ito cell)
3. BG: Control level
4. VLDL: Regulate circulating level
5. DETOX: degrade, conjugate toxic/drugs (sER)
6. IRON: store/metabolise/homeostasis
7. BILE: synthesis/secretion [1.1 l/day]
8. Remove bilirubin
9. Endocrine (vit D→25-hydroxycholecalfierol, T4→T3)

Front 20

BS of liver
- incoming [2]
- pathway [4]

Back 20

1. 75% hepatic portal vein (venous)
2. 25% hepatic artery from celiac trunk (oxygenated)

→sinusoids between hepatocytes
→central vein
→sublobular vein
→hepatic vein→IVC

Front 21

ORganization of liver [4]

Back 21

1. Liver lobule:
classic lobule, portal lobule, liver acinus

2. Classic lobule [less prominent in human liver]
- central vein at center, surr. by 5/6 portal area at angle of hexagon
- anastomosing plate of hepatocyte [1 cell thick] go radially out from vein. separated by sinusoid
- blood flows from periphery to central

3. Portal lobule
- based on exocrine function [bile secretion]:
- portal area at center of lobule [bile drainage]
- Triangular structure: border~imaginary line between 2 central vein

4. Liver acinus [smallest functional unit of liver]
- correlation between perfusion, metabolic activity, liver pathology
- diamond-shape

Front 22

Sinusoids:
- structure [4]
- function of Ito cells [2]

Back 22

- venous channel between cord of liver cell
- blood from portal area → central vein
- lined by incomplete walls [endothelium, Kupffer cell: mononuclear phagocytotic system: break down rbc]
- perisinusoidal space (of Disse): site of exchange materials between blood + liver cell

Ito cell: (hepatic stellate, in perisinusoidal space)
- store vit A,
- myofibroblast→fibrosis [collagen I, III]

Front 23

Histo features of hepatocyte
1. feature [1]
2. Cytoplasm [1]
3. organelles [5]
4. deposits [3]

Back 23

Anastomosing cell plates of liver lobule [1 cell thick], long-lived (5 months)

1. binucleation is common

2. hepatocyte cytoplasm generally acidophilic

3. Organelles
- ext. sER: enzymes→degrade/conj. toxin, syn. chol. & lipid). Hypertrophy induced by alcohol & drugs
- Basophilic regions (rER),
- mitochondria,
- small Golgi complex,
- peroxisomes (H2O2, catalase)

4. Deposit of glycogen, lipid, lipofusin pigment

Front 24

Gall bladder:
- structure [2]
- function [1]

Back 24

S:
- simple columnar mucosa + folding
- no muscularis mucosae, submucosa

F: concentrate + store bile