Lecture 5 - Glands Flashcards
Define a gland.
Aggregation of epithelial cells/single epithelial cells which secrete substances.
Distinguish between Exocrine and Endocrine.
Endocrine secrete hormones directly into the blood to be taken to distal parts of the body.
Exocrine secrete into location through a duct, mostly enzymes/lubricants.
Prolactin - Where, what type, function?
Anterior Pituitary Gland, Endocrine gland, stimulates milk production in mothers breasts.
Saliva - Where, what type, function?
Salivary Glands, specifically Buccal Cavity
Exocrine Gland
Digest substances and lubricate
Sebum - Where, what type, function?
Sebaceous Gland
Exocrine Gland
On skin/in ear, protect tissue from pathogens
Vasopressin (ADH) - Where, what type, function?
Posterior Pituitary Gland
Endocrine Gland
Prevents water loss in kidneys
T3, T4 - Where, what type, function?
Thyroid Gland
Endocrine Gland
Control metabolism
Calcitonin - Where, what type, function?
Thyroid Gland Endocrine Gland Calcium Homeostasis (works in opposite with Parathyroid Hormone)
Sweat - Where, what type, function?
Sweat Glands
Exocrine Gland
Control temperature and excretion
Colostrum/milk - Where, what type, function?
Mammary Glands
Exocrine Gland
Responds to Oxytocin and Prolactin, nourishes neonates
Somatotrophin - Where, what type, function?
Anterior Pituitary Gland
Endocrine Gland
Regulates growth of body/tissue
Oxytocin - Where, what type, function?
Posterior Pituitary Gland
Endocrine Gland
Signals uterus for baby delivery and helps ejection of milk
Lachrymal Glands - Where, what type, function?
Eyes
Endocrine Gland
Moistens eyes, also Lysozyme to kill bacteria
When are glands generated or begin generating?
During utero development, specifically week 4/5 of gestation
Describe/explain Gland Generation
FGF recieved
Proliferation of daughter cells occurs and cells undergo downgrowth into connective tissue
Exocrine: Central cells die to produce duct (canalicularisation)
Endocrine: Produce angiogenic factors that stimulate blood vessel growth (empty vessels)
How does branching occur?
Immature fibroblasts release FGF10
Epithelial cells move towards signal
Depending on activated GFs, elongation or branching occurs.
Differentiate how elongation and branching occurs.
Elongation: GF1 active, GF2 inactive
Branching: GF1 inactive, GF2 active
How does branching/elongation stop?
Shh stops it
Name 7 types of shapes for gland ducts with an example of each.
Simple Tubular Simple Branched Tubular Simple Alveolar Simple Branched Alveolar Compound Tubular Compound Alveolar Compound Tubuloalveolar
What two types of cells exist in exocrine glands?
Duct lining cells
Secretory cells
How can cells at the end of ducts behave? How does this benefit secretion?
Cells can change morphology into Myoepithelial cells ( cells w/ epithelial and smooth muscle) to help eject secretions.
Describe Salivary and Breast Glands (lecture).
Look at lecture.
Name the 3 types of secretion.
Merocrine, Holocrine, Apocrine
Describe Merocrine
Vesicles fuse with membrane of apex
Eg. Endocrine glands of pancreas
Describe Holocrine
Complete loss of cytoplasm as cells die
Eg. Sebaceous glands in skin
Describe Apocrine
Partial cytoplasm/cell loss
Eg. sweat glands or mammary glands
Describe 2 pathways of merocrine
Regulated Secretion - Secretory products accumulate into granules in vesicles and released by Calcium ion stimulation
Constitutive Secretion - Packaged in small vesicles and continuously released (mainly populates membrane w/ proteins)
What is a Cytocrine Gland?
Cells are released as secretion (spermatid in seminiferous tubule)
Describe Insulin Secretion.
Beta-cells take in glucose via GLUT-2
This is used for metabolism to produce ATP
ATP binds to K+ channel and closes it
Sulphonylurea receptor hence prevents closure of Ca2+ channel and Ca2+ influx occurs
Leads to insulin secretion
Difference between cis and trans golgi apparatus region?
Cis - ER cisternae bind to Golgi at this region and Golgi cisternae are built here.
Golgi modifies proteins in its lumen…
Trans - Vesicles leave the Golgi Apparatus to leave the cell.
Glycosylation definition
Covalent attachment of sugars by enzymes to proteins and lipids (glycoproteins and glycolipids)
Phagocytosis vs Pinocytosis
Process where phagocytes (cells) envelope or engulf other cells/particles (macrophages, dendritic cells, neutrophils etc.)
Process which liquid droplets are ingested by cells (all cells, ESP smooth muscle)
Transcytosis has 4 methods which are…
1) Via aqueous channels in intracellular junctions (Amino acids for hormone production)
2) Lipid cell membranes (Steroid hormones)
3) Carrier proteins *thyroxine transport across thyroid cell)
4) Endocytosis via surface receptors then extcytosis (cholesterol transport)
How are gland secretions controlled?
Via negative feedback primarily.
3 types - Humoral (negative feedback), Neural (negative feedback), and hormonal (hormones secreted to stimulate other glands to secrete hormones)
