Topic 5 Endocrine Conditions Flashcards
Endocrine functions
Homeostasis
Stress response
Growth and development
Sexual maturation
Endocrine regulation
Hormones are released in response to altered cellular environment; and to maintain a regulated level of certain substances or other hormones.
Regulated by three secretion patterns
- Diurnal patterns fluctuating around a 24hr cycle
- Pulsatile and cyclic patterns fluctuating around other cycles
- Patterns that depend on levels of substances circulating within blood stream
Negative feedback
Rising hormone level prevents hormone release. Prevent the systems from becoming overactive.
Syndrome of inappropriate antidiuretic hormone secretion
Hypersecretion of ADH interferes with renal water excretion. As a result, plasma sodium is diluted in larger quantities of water, leading to hypernatremia and hypo-osmolality.
Diabetes Insipidus
Hyposecretion of ADH
Neurogenic - caused by insufficient ADH release from posterior pituitary)
Nephrogenic - inadequate kidney response to hormone
Acute onset —> Polyuria and polydipsia —> dehydration without fluid replacement
Role of growth hormone
Responsible for development of muscles and bones and targets nearly every cell of the body
GH deficiency
Interferes with linear bone growth
Results in short stature or dwarfism
Tx: Somatotropin
GH excess
Results in increased linear bone growth
Gigantism, acromegaly
Tx: Somatostatin
Function of RAAS
Renin is released flowing through kidneys and diffuses throughout circulation -> plasma renin converts angiotensinogen to angiotensin 1 -> angiotension 1 converted to angiotensin 2 by ACE -> angiotensin 2 vasoconstrictive peptide causing rise in BP -> angiotensin 2 stimulates aldosterone secretion causing increased NA and H2O reabsorption increasing BP.
Action of ADH
Made in hypothalamus and released from the posterior pituitary gland. Exhibits vasoconstrictive properties. Main course of action is to stimulate reabsorption of water in the kidneys. ADH acts on the central nervous system to increase an individual’s appetite for salt and to stimulate the sensation of thirst.
Regulation of ADH
Osmoreceptors in the Hypothalamus sense the osmolality of the plasma. This stimulates the release or inhibition of ADH
What is Cushing’s syndrome
Hypercortisolism (excessive level of cortisol)
Excessive anterior pituitary secretion of adrenocorticotropic hormone, tumour on pituitary, adrenal ectopic ACTH secreting, long term use of glucocorticoids.
CM of Cushing’s syndrome
Weight gain Sodium and water retention Thinning of hair Acne Increased body hair Easy bruising Increased risk of infection with masked manifestations. Glucose intolerance Muscle wasting on extremities Breast atrophy Generalized oedema Hypertension Osteoporosis
Dx of Cushing’s syndrome
CT MRI 24 hr urine collection Plasma levels of ACTH Suppression/stimulation tests of HPA system
Tx of Cushing’s syndrome
Medication (block steroid synthesis)
Radiotherapy
Surgery (remove tumour)
