Lecture 7 & 8 - Glands and Endocrine Tissue Flashcards
What is the difference between hormonal and humoral secretion of glands?
- Hormonal is when the cell secretes hormones (usually has tropic- in name) that stimulate other cells to secrete hormones.
- Humoral is substances in the blood stream stimulate glands.
What is neural stimulation?
Neurone stimulate glands or cells.
- release neurotransmitter and bind to receptor —> secretion
What is the difference btw exocrine and endocrine glands? Some examples
- Endo: Ductless secretion of hormones directly into blood.
[Anterior pituitary gland, thyroid] - Exo: Secrete enzymes or lubrications into location/region of the body through ducts
[salivary gland, sweat gland]
What are the differences of generation of glands for exo and endo gland?
- Exo: Central cells die off and produce duct (cannalicularisation)
- Endo: Produce angiogenic factors to stimulate blood vessel growth
What are the differences btw tubular and alveolar secretory structure? Some eg?
- Tubular structure: simple tubular- intestinal gland/simple branched tubular- gastric gland & compound tubular- dudodenal gland
[X have myoepithelial cells] - Alveolar: simple alveolar/simple branched al - sebaceous glands, compound alveolar- mammary glands, compound tubulalveolar- salivary
[Have myoepithelial cells- features of both epithelial & smooth muscle –> eject secretions]
What are the different ways of classifying glands? What glands are exo and endo classified as?
- Merocrine: secretion via exocytosis, vesicle fuse w plasma membrane
- Apocrine: Partial loss of cytoplasm (mammary, sweat glands)
- Holocrine: Complete loss of cytoplasm (sebaceous, tarsal glands in eyelids)
- Exocrine = all 3, Endo = merocrine
- Cytocrine: released as a secretion (sperm)
What are the 2 ways of merocrine secretion?
- Regulated secretion: Secretory granules accumulated in large vesicles released by exo
- need Ca2+ ions, ATP - Constitutive secretion: Packaged into small vesicles and continuously released
(used to repopulate plasma membrane w plasma proteins)
Desc. holocrine secretion in sebaceous glands
- Secretory cell fills up
- Organelles degenerate and cell dies
- Plasma membrane breaks and secretum (contents) empties
- Dead cells replaced by mitotic division of basal cells
What is glycosylation of proteins? What are its functions and enzyme?
- Covalent attachment of sugars by enzymes to form glycoproteins and glycolipids
- Enzyme: GLYCOSYLTRANSFERASE
- Role: To aid protein folding, prevent protein/lipid digestion
**Diff from glycation: glycation is non-enzymatic attachment, sugar links to N atom on protein
What is the only way to transport drugs into circulation?
Receptor mediated endocytosis
Name each type of transport & list one type of molecule transported using it:
- Molecules passively diffuse through aqueous channels
- Through phospholipid bilayer
- Molecules are impermeable to P.B &
- Paracellular transport: a.a
- Transcellular transport: steroid hormones
- Endocytosis: cholesterol/drugs
Examples of hormones secreted from stomach, liver and kidney
- Stomach: Ghrelin, Leptin (control appetite), Gastrin
- Liver: Insulin-Like Growth Factor (IGF), Angiotensinogen/angiotensin, thrombopoietin
- Kidney: Thrombopoietin, renin, calcitriol
State the type of hormones, mode of action and examples
- Peptide hormone
- Activation secondary messenger
- Insulin & glucagon - Steroid hormones
- Activate gene transcription
- Cortisol, oestrogen, aldosterone - Catcholamines
- Secondary messenger
- Adrenaline/Noradrenaline - Thyroid
- Gene transcription
- T3(triiodothyronine)/T4 (tetraiodothyronine)
Where is calcitonin secreted and what are its effects?
- Secreted by parafollicular cells (thyroid gland)
- Inhibits PTH secretion –> inhibit osteoclast activity + Ca/K reabsorption in kidney (minor)
**Calcitriol inhibits PTH
What is pheochromocytoma? Symptoms?
- Chromaffin cell tumour (secrete adrenaline & noradrenaline)
- Severe hypertension, weight loss, ⬆️blood glucose
**Chromaffin cells are an example of neurocrine secretion
