Flashcards in Endocrine Physiology Deck (48):
What is the purpose of the ENDOcrine system?
- to synthesize, store, and secrete HORMONES into the BLOOD to act on target tissues.
What is the purpose of the EXOcrine system?
- secretion of substances through DUCTS.
What is the purpose of Feedback regulation?
- to maintain a balance of hormone quantity and effects.
What is the chemical modulation of metabolic events?
- adaption to surrounding environment
What is an example of systems integration of the endocrine system?
- integration of sympathetic nervous system (autonomic nervous system) with the adrenals to increase release of epinephrine and norepinephrine.
- integration of parasympathetic nervous system with GI hormones following a meal to increase splanchnic blood flow for absorption of nutrients.
From where does the endocrine system begin?
- hypothalamus and pituitary
*** What is a hormone?
- polypeptide/protein secreted by one cell cluster or organ, which is then secreted into the blood stream or bodily fluid and acts on a TARGET TISSUE elsewhere in the body.
What are some examples of hormones that act LOCALLY?
- cholecystokinin (gall bladder contraction)
- pancreatic HCO3 secretion
What are some examples of GENERAL hormones?
- epinephrine (fight or flight)
- norepinephrine (fight or flight)
- thyroid hormone (metabolism/growth)
What are the major endocrine organs?
- pineal gland
What is the endocrine function of the heart?
- secretion of natriuretic peptide, which affects whether we retain water or not.
Why would a person who has a thyroidectomy have a seizure?
- calcium deficiency secondary to removal of parathyroid glands with the thyroid tissue.
What are the 2 parts of the pituitary gland (hypophysis)?
- ADENOhypophysis (anterior)
- NEUROhypophysis (posterior)
*nerve fibers enter from the supraoptic and paraventricular nuclei sitting above the optic chiasm
From where does the majority of the blood supply enter/exit the pituitary?
- infundibular process
*aka where the pituitary hormones are exit upon release from the anterior or posterior pituitary.
Can trauma or infection of the nose/nasopharynx affect the pituitary gland?
How can anatomic pituitary problems (tumors) affect vision?
- spacial relationship to optic chiasm of optic nerves.
What is the importance of the anatomic relationship of the pituitary gland with the cavernous sinus?
- it rests within this sinus and a clot here could lead devastating changes in the blood flow.
What hormones are secreted from the ANTERIOR pituitary (adenohypophysis)?
- prolactin (milk production)
What are the 5 cell types of the ANTERIOR pituitary (adenohypophysis)?
1. somatotropes (GH)
2. cotricotropes (ACTH)
3. thyrotropes (TSH)
4. gonadotropes (FSH/LH)
5. lactotropes (prolactin)
What hormones are released from the HYPOTHALAMUS that affect the anterior pituitary?
- GHRH= GH release
- CRH= ACTH release
- TRH= TSH release
- GnRH= FSH/LH release
- PIH (prolactin inhibitory hormone)= suppresses prolactin release.
What are the POSTERIOR pituitary hormones (neurohypophysis)?
- oxytocin= uterine contractions and release of breast milk.
- vasopressin (ADH)= increases blood pressure via renal permeability (for water reabsorption) and vasoconstriction. Also increases thirst to drink more.
What is the function of ACTH on the ADRENAL CORTEX?
- stimulates ALDOSTERONE production in the adrenal cortex (zona glomerulosa) to increase Na+ and water reabsorption in the DCT to increase BP.
- stimulates the adrenal cortex (zona fasiculata) to synthesize and release CORTISOL (made from cholesterol) which helps up to deal with stress (fight or flight).
What are the STEROID hormones?
What are the TYROSINE derivative hormones? (obtained from eating protein rich foods)
*produced in the cytoplasm
What are the PEPTIDE hormones?
- all others
*produced in the rough (granular) ER and secreted from the golgi.
Are hormones present and effective in MINUTE quantities?
What is the onset of hormones?
- seconds, minutes, hours, or days.
How is hormone secretion suppressed?
- via negative feedback mechanism
What hormone types bind to cell membrane receptors?
- peptides and catecholamies (epi/norepi)
What hormones bind in the cytoplasm?
What hormones bind in the nucleus?
- thyroid hormones
What is tachyphylaxis (down-regulation of receptors)?
- decreased responsiveness
*aka you will need to increase the dosage of a drug over a prolonged period of time due to down-regulation of receptors.
What is up-regulation of receptors?
- increased responsiveness
What are some general mechanisms of action of hormones?
- changes in membrane permeability.
- intracellular enzyme activation.
- gene activation (intracellular binding).
What is the purpose of second messenger mechanisms (cAMP made from ATP via adenyl cyclase) of hormones?
- cascade reaction, which AMPLIFIES the response.
What hormones use second messenger responses?
- ADH (vasopressin)
- PTH, glucagon, catecholamines, secretin, most hypothalamic releasing hormones.
What is the "other" second messenger?
- calmodulin= four calcium binding sites that uses a different pathway from cAMP
What is the action of the STEROID hormones (cortisol and aldosterone)?
- enter the cytoplasm and bind with receptors to then enter into the nucleus to activate DNA transcription to mRNA which diffuses out into the cytoplasm for translation to proteins on ribosomes.
What is the pathway of thyroid hormones (thyroxine and triiodothyronine)?
- bind to receptor proteins of the nucleus to induce DNA transcription and production of numerous proteins.
What are some effects of supracellular endocrine disease (damage to the pituitary stalk)?
- weight gain
- weight loss
What are some results of anterior pituitary pathology?
- myxedema facies
- loss of hair
- decreased sexual characteristics
What can hypo and panhypopituitarism cause?
- hormonal deficits
What are the effects of pituitary GH?
- enhanced amino acid transport into cells to increase protein synthesis
- decreased catabolism of proteins and amino acids.
- decreased use of glucose for energy
- enhancement of glycogen deposition
- increased blood glucose; less cellular uptake.
- increased secretion of insulin to increase entry of glucose moieties into cells.
** What stimulates release of GH?
- protein deficiency
- low FFA in blood
- deep sleep
What is Kwashiorkor?
- protein deficiency in diet.
What are some abnormalities of GH secretion?
What is gigantism?
- acidophilic tumor causing maximum growth of all tissues PRIOR to puberty.