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34 Cards in this Set
- Front
- Back
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5 Types of Classification for Glands
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1) DELIVERY OF PRODUCT
a. Exocrine b. Endocrine 2) MECHANISM OF SECRETION: a. Merocrine b. apocrine c. Holocrine d. active transport 3) CELL NUMBER a. unicellular b. multicellular 4) MORPHOLOGY: (only to exocrine glands) a. SIMPLE GLANDS i. tubular ii. acinar/alveolar iii. coiled iv. tubuloalveolar (tubuloacinar) v. branched b. COMPOUND GLANDS: branched ducts! i. Acinar - nonsecreting cells (ie. exocrine pancreas) ii. Tubuloacinar - ie. submandibular glands |
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Unicellular Glands
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ENDOCRINE:
enteroendocrine (APUD) cells: basal granules! **contains SECRETORY GRANULES (SEE EM 23) vs. exocrine cells - Zymogen granules (ie. Chief cells) EXOCRINE: GOBLET CELLS - apical cytoplasm full of MUCINOGEN GRANULES surrounded by cytoplasmic cup = THECA) |
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Mucinogen/Mucus/Mucin
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Mucinogen: protein-carbohydrate compound synthesized and stored in Goblet cells
**HYDROPHILIC - so wells in fixation (BIG ROUND GOBLET CELLS) **stain with PAS **proteins stain BASOPHILIC Mucin: mucinogen + h20 - after secretion Mucus: mix of hydrated Mucin and some cellular debris and various organic salts, all suspended in h20 and mucus membrane |
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Theca
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apical cytoplasmic cup surrounds mucinogen droplet of Goblet cell = seen in EM
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Exocrine cell/glands
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WHAT: secretes into lumen - either DIRECTLY ONTO SURFACE OF EPITHELIUM OR BY A DUCT
FUNCTION: protection of epithelium, digestion, lubrication MORPHOLOGY: - luminal granules (apical) - have DUCTS around them: secretions into ducts DIVISION: Unicellular and Multicellular |
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Endocrine cell/glands
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WHAT:
!) SECRETES LOCALLY or DIRECTLY into underlying CT and/or general circulation 2) PRODUCTS reaches all organs and regions of body -DUCTLESS ie. Islets of Langerhans - local circulation MORPHOLOGY: - Basal granules - many capillaries around glands! -Ductless |
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Exocrine Multicellular Glands: Divisions based on MORPHOLOGY:
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1) SIMPLE GLANDS: NO or UNBRANCHED DUCTS
**secretory cells discharge product into lumen that's continuous with epithelial surface BUT A DUCT MAY OR MAY NOT CONNECT SECRETORY CELLS TO SURFACE a) SIMPLE TUBULAR b) SIMPLE COILED TUBULAR: different morphologies seen c) SIMPLE BRANCHED TUBULAR d) SMPLE BRANCEHD ACINAR (GRAPES)/ALVEOLAR 2) COMPOUND GLANDS: branched ducts a) COMPOUND TUBULAR b) COMPOUND TUBULAR ACINAR ie. Submandibular Gland 3) COMPOUND ACINAR |
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Simple Tubular Gland
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ie) Colon
- no duct to connect secretory cells to lumen epithelium -> THEY ARE SIMPLE INFOLDINGS OF LUMINAL EPITHELIUM **UNIFORM PACKING OF TUBULAR GLANDS THROUGHOUT MUCOSA (vs. stomach) |
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Simple Coiled Tubular Gland
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ie) sweat glands
**different morphologies seen: some circular , some tubular looking Secretory Cells -> Duct cells -> Lumen 1. Secretory cells: cells with pale cytoplasm 2. Ducts: stratified CUBOIDAL epithelium |
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Secretory Cell Epithelium VS Duct Cell Epithelium
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Secretory GLAND Cells: simple epithelium of pal pyramidal or cuboidal cells
DUCT CELLS: stratified cuboidal epithelium |
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Myoepithelial Cells
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between basal Lamina and clear cells of gland - cupping the gland
**MODIFIED EPITHELIAL CELLS: cytoplasm high concentration of ACTIN and MYOSIN to generate CONTRACTION that squeezes product into lumen **usually can only see NUCLEUS - dark and flattenede circmferentially against epithelium of secretory unit or duct **can see in LONGIT. Section **present in MOST GLANDS, STIMULATED BY ANS or HORMONES |
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Simple Branched Tubular
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ie) Stomach - NO DUCTS - but branched glands that secrete into Gastric pits!
ie) Brunner's glands **MORE DENSELY PACKED GLANDS in the MUCOSA than in SUPERFICIAL LUMINAL SIDE |
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Simple Alveolar Gland & Simple Branched acinar gland
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ie. Infant Penis/Sebaceous Glands
**SEBACEOUS GLANDS - near hair follicles - have FOAMY APPEARANCe BECAUSE HOLOCRINE MODE OF SECRETION |
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COMPOUND GLANDS: composition
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MANY LOBES MAKE LOBULES!
1) INTRAlobULAR DUCTS: within lobules 2) INTERlobULAR ducts: in between lobules 3) INTERLOBAR ducts: in between lobes |
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TYPES of compound glands
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1) Compound Acinar gland: ie) Pancreas
2) Compound Tubluoacinar Gland: Sublingal and Sbumandibular glands **ROUNDED PROFILES GREATER DIAMETER THAN TUBULAR SECRETORY ELEMENTS |
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Classifcation of Glands based on SECRETION TYPE/CHEMICAL NATURE OF SECRETION:
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1. Pure mucous acinus
2. Pure serous acinus 3. Mixed Serous acinus 4. Neither Mixed or Serous - ie) Gastric glands, mammary glands, prostate gland: secrete NEITHER mucus or serous fluid - gastric glands: parietal cells - secrete IF and HCL (neither glycoproteins or enzymes!) **BASED ON GENERAL NATURE OF SECRETIONS, NOT BASED ON ENZYMES - impossible to identify using LM techniques w/o aid of histochemical techniques |
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Pure Mucus Acinus
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ie) Brunner's glands
PALE CYTOPLASM b/c mucinogen swells and is extracted by LM prep procedures --> Selling distorts cell morphology: FLAT NUCLEUS and SQUEEZED BASALLY IN CELL SURROUNDED BY COMPRESSED CYTOPLASM |
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PURE SEROUS ACINUS
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ie) Parotid Gland
-BASOPHILIC cytoplams - full of protein -NUCLEUS: round and basal -SECRETION: enzymes secreted as glycoproteins with high protein component |
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serous vs. mucus morphology
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due to difference in relative amounts of protein and carb in mucus and serous ecretions
HIGH PROTEIN - fix better vs. HIGH CARBOHYDATE content **fixatives fix proteins rather than carbs and lipids!! |
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Mixed Serous-Mucous Acini
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mucous acini capped by serous cells = SEROUS DEMILUNE
**may be caused by artifact of fixation due to swelling of mucin that squeezes serous cells away from lumen |
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Classification based on MECHANISM of secretion
**Comparative Ultrastructure of Secreting cells |
1) merocrine
2 Apocrine 3) Holocrine 4) Active Transport Ultrastructure differences: 1) Protein Producing cells - - accumulation of apical granules - rich in ER, Golgi, mitochondria - CELL WIDE AT BASE AND KIND OF TAPERS TOWRADS APICAL END vs. Steroid producing cells: - rich in SMOOTH ER, mitochondria = sites of processing of cholesterol to steroids - see LIPID DROPLETS in Cytoplasm - Pale/clear inside |
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Merocrine (eccrine)
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secretory content released from MEBRANE BOUND SECRETORY GRANULES THAT FUSE WITH APICAL CELL MEMBRANE (adds membrane to surface but need to recycle it)
**usually with things that have membrane IN cell but NO MEMBRANE when secreted - membrane of vesicle's secretory product is bound to cell membrane and product then secreted. **products are usually PRODUCED in cell AND MODIFIED BY GOLGI - have membrane vessicle around them ie) Glycoproteins!! proteins made & carbs put on - ie. integral membrane proteins **most glands secrete this way!! ie) parotid, pancreas, mucous glands, neurons synaptic vesicles - release of NT |
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Apocrine
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large droplets of secretory produce released from apical surfact of cell WTIH A BIT OF CYTOPLASM AND SURROUNDED BY PLASMALEMMA (takes some cytoplasm with it so CELL LOSES VOLUME!)
**CAN SEE CLEAR SPACES BY APICAL ENDS - ie. FAT DROPLETS **usually with things that DO NOT HAVE MEMBRANE WITHIN THE CELL (ie. lipids - HYDROPHOBIC) ie) mammary glands |
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Holocrine
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secretory cell bursts and is entire content secreted
**ALL CYTOPLASM - VERY CLEAR LOOKING VS APOCRINE - FAT DROPLET LOOKING - condensed nucleus, condenses before product is released! **AS YOU GO TOWARDS LUMINAL END - CELLS LOOK MORE BROKEN DOWN BECAUSE LOST ITS' CONTENTS vs. BASAL ENDS: CELLS INTACT - GIVE RISE TO CELLS IN GLANDS ***HOLCRINE CELLS REPLACED BY EPITHELIUM!!!!!! ie) Sebaceous glands |
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Active Transport
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transport against gradient
ie) Parietal cell - EOSINOPHILIC! **CANAL = large canal **CANALICULI: small canals - tubulovesicular system fuses with it **TUBULOVESICULAR SYSTEM: -membranes contain H+/K+ pumps but membranes impermeable to K+ -when cell stimulated by Gastrin or Ach to release product, tubular vesicles fuse with plasma membrane of internal canaliculi which membranes ARE perm to K_ - internal canalicul produce microvilli (increase SA of cell) NET: WHEN STIMULATED, TUBULOVESICLES FUSE WITH INTERNAL CANALCIUL SO SO SEE LESS TUBULOVESICLES AND MORE CANALICULI WITH MICROVILLI TIPS - allows for ion pumps |
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Paracrine/Endocrine
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APICAL NUCLEUS< BASAL GRANULES
- secrete into the basal side ie) adipose tissue |
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GLANDS:
Produce/Secrete What? Location? |
-derivatives from epithelial tissue
- SECRETE: cellular messengers, cytokines, hormones - LOCATION: found in epithelium or embedded in underlying CT (due to invangination of epithelial cell layer into CT and it's subsequent development) |
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Parenchyma and stroma of _______ glands
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for MULTICELLULAR GLANDS
- PARENCYMA: key functional units of the organ **epithelial tissue -STROMA: supporting tissue/framework of an organ **underlying CT - supports and penetrates into gland to hold secretory elements in proper 3D arrangement |
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Mucus
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viscous secretion with HIGH concentration of GLYCOPROTEINS s that have a LOW PROTEIN content
- mainly carbs and fat |
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Serous
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low viscosity fluid with LOW concentration of GLYCOPROTEINS that have a HIGH PROTEIN
- usually enzymes or proenzymes |
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Glycoproteins
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Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending extracellularly, the extracellular segments are often glycosylated. Glycoproteins are often important integral membrane proteins, where they play a role in cell-cell interactions
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Acni
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Secretory units -
makes up MIXED GLANDS |
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Basic Categories of Glands (flow chart)
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GLANDS
- Endocrine: 1. unicellular 2. Multicellular - Exocrine: 1. unicellular 2. Multicellular a) simple i. simple tubular - no duct ii. coiled tubular - 1 duct iii. simple branched tubular - no duct iv. simp. branched acinar - 1 duct b) compound i. compound tubular ii. cmpd acinar iii. cmpd tubularacinar |
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Categories for Exocrine Glands
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1) Regulated and Constitutive Secretion
**Regulated: secretion stored in granules - will wait for SIGNALS to release product ie) salivary glands **Constitutive: RER for secretion, no granules because always making something! ie) plasma cells - always making antibodies! 2) Mode of SECRETION (vs. DELIVERY): - merocrine, apocrine, etc. 3) Cell Morpohology and product synthesis 4) Number of cells: morphological classification 5) Chemical Nautre of cells: mucous and serous |
