Hormones Flashcards
What are hormones?
Chemical messengers secreted from glands, and bind to target receptors to elicit an activator or inhibitory response within the target cell, carried by the circulatory system
How are peptide hormones synthesised?
Synthesised as pro-hormones requiring further processing (cleavage) to activate.
How do peptide hormones enter the cell?
Peptide hormones are polar, therefore are impermeable to the phospholipid bilayer of the cell surface membrane, therefore bind to receptors to transduce a secondary messenger system
How are peptide hormones stored?
In secretory vesicles
What type of secretion are peptide hormones?
Regulatory secretion
Why are steroid hormones membrane permeable?
Proteins contain a sterol group, thus can dissolve in phospholipid bilayer and diffuse into the cell
How are steroid hormones stored?
Released immediately
What is the term used to describe the secretion of steroid hormones?
Constitutive secretion
Which types of intracellular receptors to steroid bind to?
Type 1: Cytoplasmic intracellular receptor
Type 2: Nuclear
Which pituitary gland is continuous with the hypothalamus?
Posterior pituitary gland
How is the anterior pituitary gland anatomically distinct in comparison the posterior pituitary gland?
The anterior pituitary gland is distinct and not continuous with the hypothalamus; there is no presence of neural tissue
How is the pituitary suspended from the inferior side of the brain?
By the pituitary stalk
What is another term for the pituitary stalk?
Infundibulum
Where does the pituitary gland reside?
Sella turcica of the sphenoid bone
What is a supra-sella tumour?
Pituitary tumour above the sell-turcica (fossa)
What is another term for the anterior pituitary?
Adenohypophysis
Where is Rathke’s pouch?
Anterior pituitary gland, composed of glandular epithelium
Which region of the anterior pituitary gland secretes majority of hormones?
Pars distalis
Which epithelial layer separates the pars anterior from the posterior lobe?
Pars intermedia
What is the term for the portal circulation in the hypothalamus and pituitary gland?
Hypophyseal portal circulation
What is the neurohypothysis?
Posterior pituitary gland
Which hormones are secreted from the posterior pituitary gland?
Oxytocin and ADH
Which nuclei secrete oxytocin and ADH within the posterior pituitary gland?
Supraoptic
Paraventricular nuclei
Which neurones secrete hypothalamic hormones into the primary capillary plexus?
Parvocellular hypothalamic neurones
Where are hypothalamic hormones secreted into?
Primary capillary plexus
Which circulation is linked to the primary capillary plexus?
The portal hypophyseal circulation
Where do the parvocellular neurones terminate (site of primary plexus)?
Median eminence
Which hormones are released from the hypothalamus?
Hypothalamic releasing/inhibitory factors
How are the hypothalamic releasing/inhibitory factors transported to the anterior pituitary?
The portal hypophyseal circulation
Primary capillary plexus to the secondary capillary plexus
Where is the median eminence located?
Infundibulum
What type of cells comprise the anterior pituitary gland?
Endocrine cells
What are the 5 classes of endocrine cells?
Lactotrophs Somatotrophs Gonadtrophs Thyrotrophs Corticotrophs
Which plexus releases hypothalamic inhibitory/releasing factors into the anterior pituitary gland?
Secondary capillary plexus