(PM3B) Endocrine Systems Flashcards
What does the endocrine system and NS regulate?
(1) Growth
(2) Reproduction
(3) Development
(4) Senescence - age deterioration
What are the three classes of hormones?
What can be said for their hydrophilicity?
(1) Proteins/ peptides - all hydrophilic
(2) Cholesterol derivatives - all hydrophobic
(3) Modified amino acids - hydrophilic (adrenaline) or hydrophobic (thyroid hormones)
What factors affect circulating hormone level?
(1) Rate of secretion - endocrine gland
(2) Rate of metabolism - target tissue/ kidney/ liver/ blood
(3) Serum binding protein availability
What type of hormones must be injected? Why? State an example.
Protein hormones
They are digested in the stomach
Growth hormone
What is an ectopic hormone-secreting tumour?
A tumour not in an endocrine gland which is producing hormones
What is a tumour that produces hormones in a place that does not normally produce hormones called?
Ectopic hormone-secreting tumour
What is the most common immunological cause of hyper secretion in the thyroid?
Graves’ disease
Which dysfunction is a reason for a hormone having no effect on a usually targeted tissue?
End organ sensitivity/ resistance to hormone
What are the 2 types of organ sensitivity defect called?
(1) Genetic defect
- e.g. Laron syndrome
- Increases production of non-functioning growth hormone
(2) Acquired defect
- e.g. Type 2 DM
- Impaired insulin receptor signalling with normal levels of insulin
What is a pituitary adenoma?
Growth of a functional tumour inside the endocrine gland
Often benign
(1) What hormone does the parathyroid secrete?
(2) What does this hormone affect?
(1) Parathyroid hormone
(2) Controls calcium levels
What are the 3 types of endogenous rhythm?
What do they mean?
Give an example.
(1) Ultradian - cycles in minutes - GnRH (hormone) pulses
(2) Circadian - cycles in days - testosterone/ cortisol
(3) Infradian - cycles in months - LH - 28 day cycle
What is an ultradian rhythm?
Cycles in minutes
What is a circadian rhythm?
Cycles in days
What is an infradian rhythm?
Cycles in months
What type of feedback mechanism is most common?
Negative feedback
What is an example of a closed loop mechanism?
Negative feedback in homeostasis
What is an example of a positive feedback loop?
Milk-ejection reflex - caused by oxytocin
Pre-ovulatory LH surge - caused by oestrogen
What changes in the EXTERNAL environment can the hypothalamic-pituitary system respond to?
(1) Photoperiod - day/ night cycle
(2) Temperature
(3) Food availability
(4) Mate availability
(5) Stress
What changes in the INTERNAL environment can the hypothalamic-pituitary system respond to?
(1) Target organ feedback signals
(2) Nutritional status
(3) Water/ salt balance
(4) BP/ HR
(5) Pregnancy
(6) Trauma/ disease
What is the bone cavity that the pituitary gland sits in called?
Sella turcica
What is the composition of the pituitary gland?
Two lobes
(1) Anterior pituitary
(2) Posterior pituitary
What is a parvocellular peptidergic neurone?
A neurone that controls hormone secretion from anterior pituitary - e.g. TSH
What is a magnocellular peptidergic neurone?
A neurone that controls hormone secretion from posterior pituitary - e.g. oxytocin/ vasopressin - ADH