Glands introduction Flashcards
(29 cards)
What is a gland?
An epithelial cell or an aggregate of epithelial cells that are specialised for the secretion of a substance
Endocrine glands (3 things)
- Ductless
- Secrete into bloodstream
- Substances (hormones) affect target tissues
Exocrine glands (3 things)
- Ducts
- Secrete into location or region of the body
- Secrete enzymes or lubricants
Examples of endocrine glands (4 things)
- Pituitary gland
- Thyroid gland
- Parathyroid gland
- Pancreas (islets of langerhans)
Examples of exocrine glands (6 things)
- Salivary glands
- Mammary glands
- Pancreas
- Sudoriferous glands (sweat)
- Sebaceous glands
- Lachrymal glands (eye)
Adenogenesis of exocrine glands (5 things)
- Growth hormone received
- Proliferation of cells occurs and EC protein degradation enzymes produced
- Epithelial cells invade space created
- Central cells die off to produce duct (canalicularisation)
- Link to mother cells remained and significant amount of branching
Adenogenesis of endocrine glands (5 things)
- Growth hormone received
- Proliferation of cells and EC protein degradation enzymes produced
- Epithelial cells invade space created
- Produce angiogenic factors to stimulate blood vessel growth in and around epithelial cells
- Link to mother cells broken via apoptosis and virtually no branching
How does branching occur?
Via reciprocal growth- one factor turned on when other is turned off
Simple tubular glands
Large intestine
Simple branched tubular glands
Stomach
Simple coiled tubular glands
Skin (eccrine)
Simple acinar/alveolar glands
Urethra of penis
Simple branched acinar/alveolar glands (2 things)
- Stomach
- Sebaceous glands
Compound tubular glands
Duodenum
Compound acinar/alveolar glands (2 things)
- Pancreas
- Mammary glands
Compound tubuloacinar/alveolar glands
Submandibular salivary gland
What is a merocrine gland?
Fusion of vesicles with apical membrane (e.g. pancreas)
What is an apocrine gland?
Partial loss of cytoplasm (e.g. lactating mammary gland, sweat glands in axilla)
What is a holocrine gland?
Cells are released as a secretion (e.g. sperm in testis)
2 types of merocrine secretion
- Regulated: accumulation of secretory granules in large vesicles which are released upon stimulation
- Constitutive: secretory product packaged into small vesicles and continuously released
What ion does merocrine secretion require?
Calcium (Ca2+)
How does sulphonylurea work in diabetics?
Binds to ATP-sensitive potassium channel and keeps it closed- mimics function of ATP
What is released by breasts in apocrine secretion?
- Fats (neonatal period)
- Milk proteins and fats (lactation)
Holocrine secretion mechanism (4 things)
- Secretory cell gradually fills up with secretory granules
- Cell organelles degenerate and cell dies
- Plasma membrane breaks and contents (secretum) empties
- Dead cells replaced by mitotic division of basal cells
