Session 5: Glands & Endocrine Tissue Flashcards
Examples of Endocrine glands and the hormones released
Anterior Pituitary Gland:
ACTH, LH, FSH, TSH, prolactin, somatotrophin
Posterior Pituitary Gland:
Vasopressin, oxytocin
Thyroid Gland:
Thyroid hormone (T3, T4)
Parathyroid Gland:
Parathyroid hormone
What type of tissue are glands made of ?
Simple cuboidal
Examples of Exocrine glands
Salivary gland
Pancreas
Mammary
Sweat glands
Sebaceous gland
Lachrymal glands
Adenogenesis
Synthesis of gland
Explain adenogenesis of exocrine, endocrine glands
- Growth signal received
- Proliferation of daughter cells occur and “extracellular protein degradation enzymes”produced
3.Epithelial cells invade space created (protease)
Exo:
Canalicularisation (central cells dies off to produce duct)
-Link to mother cells remains
-Significant amount of branching
Endo:
Produce angiogenic factors to stimulate blood vessel growth (in and around epithelial cells)
-link to mother cells broken via apoptosis
-virtually no branching
How does branching occur (lungs)
- FGF10 released by immature fibroblasts (mess chg all stem cells)
- Epithelial cells move towards the signal
(i) Tubule elongation (GF 1: active, GF 2: inactive)
or
(ii) Tubule branching (GF 1: inactive, GF 2: active)
- Elongation and branching stopped by Shh (Sonic the Hedgehog)
The activity of growth factors in tubule elongation & tubule branching
Elongation:
Growth factor 1- ACTIVE
Growth factor 2- Inactive
Branching
Growth factor 1- Inactive
Growth factor 2- ACTIVE
2 types of epithelial cell in exocrine glands
- Cells lining the ducts
- Cells that make secretory products
Definitions:
-Striated
-Demilune
-Intercalating
-Acinus
-striped
-half-moon
-insets between
-sac like = alveolar
2 types of secretion
-Mucous (closed cavity, sticky fluid)
-Serous (open to exterior, watery fluid)
4 different modes of secretion
-Merocrine
-Apocrine
-Holocrine
-Cytocrine
Define Merocine Gland & give an example
Fusion of vesicles with apical membrane
e.g. Acinar & Endocrine glands of the pancreas
Define Apocrine Gland & give an example
Partial loss of cytoplasm
e.g. lactating mammary gland, sweat glands in the axilla and external genitalia
Define Holocrine Gland & give an example
Complete loss of cytoplasm
e.g. Sebaceous gland in skin, tarsal glands in eyelid
Define Cytocrine Gland & give an example
Cells are released as a secretion
e.g. spermatic (spermatozoa) in the seminiferous tubules (testis)
Two pathways of Merocrine secretion
- Regulated secretion
-secretory granules accumulate in large vesicles
-released by exocytosis upon stimulation
-Ca+2 triggered - Constitutive secretion
-packaged into small vesicles
-continuously released to the cell surface
Purpose of Merocrine secretion
To repopulate the plasma membrane with plasma proteins
A clinical example of Merocrine secretion
Diabetes 1
Explain an example of Apocrine secretion
Neonatal period: Only fats secreted by apocrine secretion
During Lactation: Fats & proteins are released by apocrine secretion
(milk proteins are released by Merocrine secretion)
Explain an example of Holocrine secretion
Sebaceous gland
Define Glycosylation
(enzyme-catalysed reaction)
The covalent attachment of sugars by enzymes to proteins & lipids to form glycoproteins & glycolipids
Define Glycation
(non-enzymatic reaction)
The covalent attachment of a sugar to a protein/lipid
Describe regulated Merocrine secretion
Difference between hyper/hypothyroidism
Hyperthyroidism: ⬆️ T3+T4, ⬇️ TSH
Hypothyroidism: ⬇️ T3&T4, ⬆️ TSH
