Glands Flashcards
What are the x2 types of glands?
-Endocrine
-Exocrine
What are endocrine glands?
Secrete hormones directly into bloodstream
What are exocrine glands?
Release their substances either:
-Directly onto an ep surface
or
-Via duct systems
Name some endocrine glands.
-Hypothalamus
-Pituitary *
-Thymus
-Thyroid *
-Parathyroid
-Adrenal *
-Pancreas (part of it is endo & part is exo) *
-Ovary
-Testis
Name some exocrine glands.
-Salivary (x3 parts: parotid, submandibular & sublingual)
-Mammary
-Pancreas (part of it is endo & part is exo) *
Structure of thyroid gland?
-Cells arranged into follicles (spherical shaped)
-Follicles - lined w/ single follicular ep = cuboidal ep
-Follicles - surrounded by reticular fibres
-Follicle cavity - filled w/ colloid ==> follicular cells synthesise & secrete colloid!!!!!!!!!!!!!! (& thyroid hormones)
–> colloid is made up of thyroid hormones
-CT septa from thyroid gland caspule - extends into gland’s interior -> divides gland into lobules
-Capillary network surrounds follicles -> as endocrine glands release secretions (thryoid hormones) directly into blood
-Gland also contains parafollicular/C cells
–> found peripehrally in basal lamina of follicular ep OR as clusters between follicular cells - contain secretory granules containing calcitonin hormone
–> synthesise & secretes calcitonin
What is colloid made up of?
Thyroglobulin = iodinated glycoprotein - is inactive storage form of thyroid hormones (T3 & T4)
What colour does colloid (cavity of follicles) show up as?
Stain pink - eosinophilic
-As is basic
What colour do C cells show up as?
Stain lighter than follicular cells - pink - eosinophilic
Role of calcitonin secreted by C cells?
When conc of Ca2+ in blood increases -> transports Ca2+ from blood into bone -> makes bone stronger/denser
(Parathyroid hormone does the opposite)
Describe how thyroid hormones are secreted?
- Follicular cells take up stored thyroglobulin
- Transport thyroglobulin across follicular ep
- Release thyroid hormones into capillaries surrounding follicle
Label.
Where is the pituitary gland in the skull?
Surrounded by sellae turcica
-> in which the hypophyseal fossa is where pituitary gland sits
Give the embryonic origin terminology, pituitary subdivision & clinical terminology for the pituitary gland.
-Adenohypophysis = ant. pit - x3 subdivisions
-Neurohypophysis = post. pit - x2 subdivisions
(Infundibulum = pit. stalk)
What are the 3 subdivisions of the adenohypophysis?
-Pars distalis
-Pars intermedia
-Pars tuberalis
Describe the structure of pituitary gland?
-Pars distalis (A) -> forms from ant. wall of Rathke’s pouch
-Pars intermedia (A) -> forms from post. wall of Rathke’s pouch - along with <- pars nervosa (N)
-Pars tuberalis (A) -> forms collar of cells/surrounds infundibulum (N)
-Pars distalis = largest
-Pars intermedia = thin cell layer between distalis & neurohypophysis
A = adenohypophysis = ant. pit - green on diagram
N = neurohypophysis = post. pit - grey on diagram
Blood vs (IN PARS NERVOSA!!!) -> hormones enter
***Neurohypophysis:
-Paraventricular nucleus - contains ADH/vasopressin synthesising neurones
-Supraoptic nucleus - contains oxytocin synthesising neurones
**SEND PROJECTIONS TO NEUROHYPOPHYSIS
–> these hormones bound to glycoprots pass down axons of hypothalamopituitary tract through pit. stalk to post. pit. - where are stored in distended terminal axon parts
–> hormones released from post. pit - controlled by nervous impulses passing down axons from hypothalamus (= neurosecretion)
Label.
PP = post. pit. –> lighter/pink stained
AP = ant. pit. –> darker/purple stained
P = pit. stalk/infundibulum
H = hypothalamus
V = ventricle (lateral)
O = optic chiasm
Explain the difference in the staining (H&E) between the posterior & anterior pituitary.
Posterior = Neurohypophysis -> lighter staining:
-Contains non-myelinated axons = neurosecretory cells
-Contains glial cells & axons whose cell bodies are in hypothalamus
Anterior = Adenohypophysis -> darker staining:
-Pars distalis - contains x2 cell types:
Chromophobe -> do NOT take up H&E stain
Chromophil cells -> divided into acidophils (stain orange/red) & basophils (stain blue/purple)
–> & ant. pit. comntains more cells
Label.
For the 3 subdivisions of the adenohypophysis - what cells do they contain?
Pars distalis = all x5
Pars tuberalis = gonadotropes (as basophils)
Pars intermedia = basophils (unclear which ones)
Structure of adrenal glands?
*Capsule
*Cortex: (outer) = steroid secreting cells
-Zona glomerulosa
-Zona fasciculata
-Zona reticularis
*Medulla (inner) = chromaffin cells
Label.
What are the islets of Langerhans?
= Clumped masses of pale-staining endocrine cells embedded in exocrine acinar tissue of pancreas
–> surrounded by the exocrine portion of pancreas
-Spherical
-Made of smaller cells - α, β & δ
-Separated from exocrine tissue by fibrocollagenous capsule
Structure of the exocrine portion of the pancreas?
*Compound acinar gland = overall gland structure - made up of…
-Acini - made of acinar cells (basally located nuclei) ==> SECRETE DIGESTIVE ENZYMES!
-Intercalated ducts/small intralobular ducts & large intralobular duct = low simple squamous-to-cuboidal ep
(intercalated ducts - secrete HCO3-)
-Interlobular duct - where cells become low cuboidal
–> leads to - main duct/pancreatic duct = stratified cuboidal ep
**Main/pancreatic duct - empties into duodenum
-Within gland - ducts run through CT of septa & branch lots until smallest branch reaches secretory portion of gland (in acini region)
x2 parts to exocrine pancreas:
-Secretory portion = acini region
-Duct portion
What are exocrine glands categorised as?
-Unicellular
-Multicellular
–> then multicellular are subclassified based on presence of tubule & acini AND presence (yes or no) & configuration of duct (simple OR compound)
-Simple = single unbranched unit
-Compound = multiple branched ducts
Name the x3 types of cell secretion methods?
-Merocrine
-Aprocrine
-Holocrine
What is merocrine secretion?
Exocytosis of secretory products - FROM contents contained within memb-bound vesicles (so no longer in vesicle!)
What is apocrine secretion?
Secretory product released with intact vesicle & some cytoplasm from apical region of secretory cell
What is holocrine secretions?
Entire cell is released during secretory process
What are the x3 types of salivary glands?
-Parotid
-Submandibular
-Sublingual
What is the duct system in the salivary glands?
Salivary glands = made of secretory acini & ducts
-Acini = secretory portion
-Duct = duct portion
x2 types of secretions - serous & mucous
–> SO acini are either be serous, mucous or both (as acini = secretory portions of the exocrine duct system/gland)
-Serous acini = basally located round nuclei
-Mucous acini = basally located flat nuclei
-Serous demilune = serous cells @ distal end of mucous secretory unit -> of mixed salivary glands
-Myoepithelial cells = contract releasing secretions from acini into duct - involuntary
- Secretory region - acini
- Intercalated duct - simple squamous
- Striated duct - simple cuboidal-to-columnar
(2 & 3 = intralobular duct) - Interlobular duct (formed by anastamosis of striated ducts) - simple columnar to striated columnar
- Lobular duct - striated columnar ep
- Main/major duct
Structure/how to identify parotid glands?
-Serous secretions - so has serous acini -> which have basally located round nuclei
–> serous cells - secrete α-amylase -> that initiates carb hydrolysis
-Compound (branched)
-Tubuloacinar
-Irregular collagenous CT capsule provides septa -> subdivides glands into lobes & lobules
-Structure of ducts - follows that of other salivary glands
Septa subdivide parotid gland lobe into lobules
-Striated ducts - have round nuclei near centre of cells composing duct
-Ducts deliver salivary secretions into oral cavity
Structure/how to identify submandibular gland?
-MIXED gland - so has serous demilunes (= mixed acini)
–> so have serous & mucous secretions
(serous acini dominate!)
-Serous demilunes - have outer serous cells & inner mucous cells making up the acinus
*Serous cells - have basally located round nuclei
*Mucous cells - have basally located flat nuclei
-Compound
-Tubulo-acinar glands
-Structure of ducts - follows that of other salivary glands
-Paired gland
-Ovoid shape
-Below mandible
-Ducts open into floor of mouth - bilaterally (x1 on either side of frenulum of tongue)
-Myoep cells -> between ep & basement memb of acini ==> to squeeze secretions towards major ducts
Label - submandibular salivary gland?
SAc – Serous acini
SeD – Serous demilunes
MA – mucous tubules
SD – Striated duct
