Hormones Flashcards
Name and describe the three hormone production patterns?
Chronic/constitutive: relatively constant concentration.
Acute/stimulated: released in response to a stimulus.
Cyclic/pulsatile: regular increase and decrease in secretion.
Name the three classes of hormones.
Peptide.
Steroid.
Amine
Where are peptide hormones stored and how long is the half-life
Stored in vesicles, ready to be released at any time.
They have a short half-life so prolonged action requires continual secretion.
What are steroid hormones derived from and where are they synthesised?
Derived from cholesterol and synthesised in SER of gonads and adrenal glands.
How are steroid hormones stored and transported?
Esterified for storage and bound to plasma protein when transported. These occur because cholesterol-based hormones are hydrophobic.
How is bound/unbound steroid equilibrium maintained?
When unbound hormone enters the cell, plasma protein-bound hormone unbinds in order to restore equilibrium and promote a continual release of hormone.
Which receptors do each type of hormone bind to?
Peptide: extracellular receptors
Steroid: intracellular (transcription factor pathway)
Amine: extracellular or intracellular [thyroide only]
Which amino acid acts as the precursor for which two hormone subclasses?
Tyrosine acts as a precursor to catecholamines and thyroid hormones.
Comment on the half-life of amine hormones and which subclass contains two amino acids and iodine.
The half-life is very long.
Thyroid hormone contain two tyrosine molecules and iodine molecules.
Which stalk-like structure connects the hypothalamus and pituitary gland
Infandibulum
Which region of the pituitary is considered true endocrine tissue and neuroendocrine?
The anterior pituitary is true endocrine tissue.
The posterior pituitary is neuroendocrine tissue.
What do the 2 capillary beds connecting the hypothalamus and anterior pituitary function as and what are they known as?
The capillary beds are a portal system of communication known as adenohypophysis.
What is the name of the structure that stores and secretes neurohormones synthesised by the hypothalamus?
Neurohypophysis
Which neurohormones does the hypothalamus produce and which cells synthesis them
magnocellular cells produce vasopressin and oxytocin.
What is the function of vasopressin?
Induce kidneys collecting ducts to reabsorb more water and vascular smooth muscle to increase the smooth muscle.
What is the function of oxytocin?
Initiate uterine contractions in a positive feedback loop.
cause milk ducts to lactate.
What are AP tropic hormones?
Anterior pituitary hormones that inhibit or stimulate the release of hormones from glands around the body.
What do somatotrophic cells release?
Growth hormone
What do lactotrophic cells release?
Prolactin
What do thyrotrophic cells release?
Thyroid stimulating hormone
What do gonadotrophic cells release?
Luteinising hormone and follicle-stimulating hormone.
What do corticotrophic cells release?
Adrenocorticotropic hormone
What 3 main things does growth hormone stimulate?
1) Prechondrocyte maturation
2) Cellular uptake of amino acids
3) Breakdown of lipids
What does Thyroid hormone stimulate?
1) Expression of GH
2) Initiation of puberty
3) Eventual epiphyseal plate ossification
What do mature chondrocytes secrete and what does this stimulate?
Insulin-like growth factor 1 (IGF1) stimulates chondrocyte proliferation, protein synthesis and cell division.
What does insulin stimulate?
1) Cellular glucose uptake
2) Protein synthesis
3) Inhibition of protein degradation
What tissue does the adrenal tissue arise from and what does it synthesise?
The medulla arises from neural tissue and secretes catecholamines (amine)
What tissue does the adrenal cortex arise from and what does it synthesise?
The cortex arises from non-neuronal tissue and secretes steroid hormones
Which stress response do catecholamines regulate and how does the process come about?
Catecholamines mediate the fight or flight response by; inducing rapid glycogen to glucose breakdown; fat reserve breakdown and increased cardiac and ventilation rate.
This is done to increase the energy available to the body.
Which region of the adrenal cortex secretes androgens?
Inner most region: Zona reticularis
Which region of the adrenal cortex secretes glucocorticosteroids?
The largest and central layer: Zona fasciculata
Which region of the adrenal glands secretes aldosterone?
The outer most layer: Zona glomerulosa
What are glucocorticosteroids?
1) Steroid hormones that include cortisol
2) circadian and stress-inducible
What does cortisol mediate?
Cortisol mediates a stress response long term.
How does cortisol prevent damage from certain internal conditions long term?
Cortisol prevents hypoglycaemia and depletion of glucose stores by:
1) stimulating gluconeogenesis from non-CHO sources.
2) Protecting long term glucose stores.
3) mediating levels of glycogen stores.
How can excessive cortisol be damaging?
Cortisol suppresses many functions such as immune responses and cognitive processes, therefore excessive levels can impede proper development.
Name androgens
oestrogen and testosterone.
What is the role of mineral corticosteroids?
Regulate concentrations of ions, and therefore the water content of the body.
When released from the kidney, what does renin do?
Converts plasma angiotensinogen to angiotensin 1.
What does angiotensin-converting enzyme (ACE) do?
Converts angiotensin 1 to angiotensin 2
What stimulates the adrenocortex to secrete the mineral corticosteroid, aldosterone?
Angiotensin 2 promotes the conversion of cholesterol to aldosterone.
What effect does aldosterone have?
Increases renal collecting duct reabsorption of Na+ by increasing expression of Na+ transporter proteins.
This conserves water and blood volume.
