HPA Flashcards
What are the typical 4 features of a feedback mechanism?
1-System variable
2-Set point
3-Detector
4-Corrective mechanism
What are 6 of the major hormonal contributors to homeostasis?
1-Thyroid hormone (basal metabolism)
2-cortisol (energy metabolism/stress response)
3-Mineralcorticoids (plasma volume)
4-Vasopressin(ADH) (plasma osmolalility via water excretion)
5-Parathyroid hormone (calcium and phosphorous level)
6-Insulin (glucose levels)
What is a neurocrine hormone?
secretion by a neuron to the bloodstream
What are the 3 chemical classes of hormones?
1-Steroid
2-Peptide/protein
3-Amine (tyrosine derivatives)
What are the two general categories of hormones?
1-Lipophilic (non polar) fat soluble (bind intracellularly for response)
2-Hydrophilic (polar) water soluble (bind extracellularly for response)
What are the two groups of hormones derived from tyrosine?
1-Thyroid hormone(bind nuclear receptors)
2-Catecholamines (bind surface receptors ie. epinephrine/norepinephrine)
What is characteristic of Peptide/protein hormones?
- Water soluble
- most numerous
- often produce precursors that are cleaved post translationally to become active
The _________ is formed in the ER before getting broken down to _____________ in golgi apparatus and then secreted as a __________
Preprohormone, Prohormone, hormone
What 9 hormones are examples of having pro hormones?
- Somatostatin
- Insulin
- Glucagon
- Calcitonin
- ADH
- Gastrin
- Enkephalin
- Parathyroid Hormone
- ACTH
How do hydrophilic hormones pass on their message?
binding surface receptors that use second messenger pathways to transduce the signal (often G proteins)
What are steroid hormones derived from?
Cholesterol
What is characteristic of Steroid hormones?
- Lipid soluble
- are carried by hormone specific plasma binding globulins in the blood (bound hormones act as a reservoir)
Lipid soluble hormones cross cell membranes and form what?
Hormone receptor complexes that act as transcription factors to regulate the target gene
What two feedback regulations happen with hormones?
- Negative feedback: Hormone down regulates
- Positive feedback: hormone up regulates (rare, partuition is the main example)
What are the three lobes of the pituitary gland?
1-Anterior pituitary
2-Intermediate lobe/pars intermedia
3-Posterior pituitary
What connects the hypothalamus to the pituitary?
Infundibulum
How does the Hypothalamo-hypophysial portal system interact with the anterior pituitary?
Releases hormones into the capillaries that reach the anterior pituitary to either stimulate or inhibit secretion of hormones
How does the Hypothalamo-hypophysial portal system interact with the posterior pituitary?
Oxytocin and ADH are synthsized by hypothalamus and transported to posterior pituitary for storage until needed.
What is the HPA axis primarily associated with?
Stress
Feedback loops ensure serum ___________ homeostasis
osmolalility (primarily through the kidneys)
What are the three zones of the adrenal gland cortex and what does each zone secrete?
1-Zona glomerulosa- Mineralcorticoids
2-Zona Fasciculata- Glucocorticoids
3-Zona reticularis- Adrenal androgens
The medulla of the adrenal gland is responsible for secreting what?
Catecholamines (epinephrine/norepinephrine) short term stress response
What affect does aldosterone(mineralcorticoid) have?
promotes sodium reabsoroption and postassium excretion in renal collecting and distal tubules
Cortisol works in a feedback loop to ___________ the HPA axis
inhibit
What are the 3 main categories of endocrine disorders?
1-Endocrine gland hyposecretion
2-Hormone resistance
3-Hormone excess
