PED1003/L19 Endocrine System Flashcards
Define a hormone.
A chemical/protein synthesised by specific tissues and secreted into the bloodstream whereby it is carried to non-adjacent sites in the body and exerts its actions
What is regulated by the pineal gland?
Melatonin release
What are steroid hormones synthesised from?
Cholestrol
Give 2 features of steroid hormones.
Lipophilic
Hydrophobic
By which action do steroidal hormones work?
Intracellular receptors
What are non-steroid hormones synthesised from?
Polypeptides
Modified amino acids
Tyrosine & tryptophan
Give 2 features of non-steroid hormones.
Lipophilic
Hydrophobic
By which mechanism do non-steroid hormones work?
Cell surface receptors
Give 3 examples of steroid hormones.
Cortisol & aldosterone (AC)
Oestrogen & progesterone (O&P)
Testosterone (testes)
Give an example of a tyrosine derived hormone.
Catecholamines - adrenaline & noradrenaline
Thyroid hormones - triiodothyronine & thyroxine
Dopamine
Give an example of a tryptophan derived hormone.
Melatonin (PG)
5-HT
Give an example of a protein derived hormone.
TRH, GnRH & GHRH
TSH, FSH, LH, GH, ACTH, ADH, Oxytocin
Insulin, Glucagon
Describe feedback control of cortisol. (6)
Physical or emotional stress
Hypothalamus produces corticotropin-releasing hormone (CRH)
Anterior pituitary produces Adrenocorticotropic hormone (ACTH)
Adrenal cortex produces cortisol
Adrenal medulla produces adrenaline
What is the effect of cortisol? (2)
Increased fat & protein metabolism
Slowing increasing glucose
What is the effect of adrenaline?
Rapidly increased HR, BP and glucose
Describe the cascade of events that occurs when there is a low blood volume/pressure/high osmolarity. (6)
Low BP/vol detected by baroreceptors
High osmolarity detected by osmoreceptors in hypothalamus
Posterior pituitary releases ADH
ADH acts on distal tubule of V2 receptors in kidney
Increased water reabsorption
ADH acts on V1 receptors in SM to cause vasoconstriction (increase BP)
Describe the cascade of events that occurs when high blood sugar is detected. (2)
High blood sugar detected by beta cells which secrete insulin
Insulin acts on tissue and liver to decrease blood sugar
Describe the cascade of events that occurs when low blood sugar is detected. (2)
Low blood sugar detected by alpha cells which secrete glucagon
Glucagon acts on liver which performs glycogenolysis and increases blood sugar
Describe substrate controlled hormone release in beta cells. (4)
Glucose enters cell and enters Krebs cycle
Increased ATP blocks ATP-sensitive K+ channel
Calcium channel opens and Ca2+ enters cell
Insulin storage vesicles fuse with cell membrane
Define neuronal control and give an example.
Hormone is released directly in response to neuronal stimulation
ADH & CRH
Define tropic control and give an example.
Hormone is released in response to stimulation from another hormone
ACTH & cortisol
Define substrate control and give an example.
Hormone is directly influenced by circulating blood levels of substrate that hormone itself controls
Glucagon & insulin
Define feedback control.
Exceeding a certain level of hormone inhibits further hormone release
