Hormone function and types of hormones (3)
Function: Signals molecules or chemical messengers that transport information from one set of cells (endocrine) to another (target)
Types:
-Peptide/protein (insulin, GH, ADH, angiotensin, EPO)
-Amine/amino (catecholamines, thyroxine)
-Lipids (steroid, cortisone, aldosterone, estrogen)
Hormone receptors
Peptide/protein
-Receptor site on cell surface is activated and generates 2nd receptor (cAMP used by vaso, TSH, parathyroid hormone)
Lipid
-Attracts specific hormone, lipophilic, diffuse into the cell (thyroid and steroid hormones)
Hormone regulation (3 control mechanisms)
Endocrine system is involved in regulation of ____
Behavior, growth, metabolism, fluid status, development, reproduction
Endocrine vs autocrine vs paracrine
Hormone enters…
Endocrine glands
Pituitary Thyroid Parathyroid Adrenal Pancreas Ovaries Testes Placenta
Body functions modified by the pituitary gland
Homeostatic
Developmental
Metabolic
Reproductive
Pituitary glad located ___ connected to ___
Located at base of brain
Connected to hypothalamus
Anterior vs posterior pituitary communication with hypothalamus
Anterior:
-Via vascular system
Posterior:
-Via neural pathways
Hypothalamus connection controls pituitary hormone secretion
-No BBB between the two so feedback/communication can occur
6 hormones secreted by anterior pituitary
Growth hormone (GH)
Adrenocorticotropic hormone (ACTH)
-Cortisol/androgenic hormone release from adrenal cortex
Thyroid-stimulating hormone (TSH)
Follicle-stimulating hormone (FSH)
-Ovarian follicle development, spermatogenesis
Luteinizing hormone (LH)
-Ovulation, corpus luteum development, testosterone production
Prolactin
-Mammary gland development, milk production
-Inhibits synthesis/secretions of LH, FSH
Causes of anterior pituitary hyposecretion
Panhypopituitarism
Lack of pituitary hormones
Treatment of pituitary tumor
Surgical removal
Anterior pituitary hypersecretion
Most commonly tumors secrete prolactin, ACTH, or GH
Growth hormone
Hypothalamus regulates GH activity (negative feedback)
GH hyposecretion vs hypersecretions
Hyposecretion
-Dwarfism, hypoglycemia
Hypersecretion
-Usually caused by GH secreting pituitary adenoma
-Acromegaly -> thick large bones, enlarged organs (cardiomyopathy, HTN, atherosclerosis, LVH), increased lung volumes (VQ mismatch, increased extrathoracic obstruction), coarse facial features
-Gigantism -> if GH is elevated before adolescence, grow to 8-9 feet
-Glucose intolerance, diabetes (GH antagonist to insulin)
-Treatment: Remove pituitary tumor
Anesthetic plan for GH hypersecretion pituiraty tumor removal
Examine airway
Posterior pituitary hormones (2)
Antidiuretic hormone (vasopressin, ADH)
-Controls water excretion/reabsorption in kidney
-Regulates serum osmolarity
Oxytocin
-Stimulates milk ejection during lactation
-Uterine smooth muscle contraction
-Derivatives used to induce labor/decrease postpartum bleeding
ADH stimulation
When plasma osmolarity is 284mOsm/L
-Normal 285-290
10-20% decrease in plasma volume or BP
-Baroreceptors send signal via vagal/glossopharyngeal nerves to hypothalamus -> hypothalamus increases ADH synthesis and release
Pain, emotional stress, nausea, hemorrhage
Diabetes insipidus
=Low ADH neurogenic (or inability of renal ducts to respond nephrogenic)
Diabetes insipidus anesthetic considerations and treatment
Assess fluid status, electrolytes
-Surgery increases ADH release so pre-op vasopressin isn’t usually necessary with partial DI
-Monitor plasma osm, UOP, serum Na q1h
-Give isotonic fluids until serum osm=290, then hypotonic
Treatment (complete DI)
-Meds that increase ADH release or increase receptor response to ADH
-Short term=vasopressin
-Long term=desmopressin
Syndrome of inappropriate anti-diuretic hormone (SIADH) (characteristics, anesthetic consideration, treatment)
=High ADH levels
-Water reabsorbed in tubules even when hypoosmolar
-Low UOP -> water intoxication, hyponatremia -> brain edema
Slow emergence
Treatment
-Mild, without s/s of hyponatremia: fluid restriction (800mL/day)
-More severe: hypertonic saline with Lasix
-Correct Na levels slowly
Thyroid gland
Function
-Secrete thyroid hormones to regulate cellular metabolism and calcium balance
Nerves in proximity
-Recurrent laryngeal nerve and external motor branch of superior laryngeal nerve
3 hormones secreted by the thyroid gland
T4 -Thyroxine -93% of hormone -less potent in blood -prehormone: converted to T3 at tissue sites T3 -Triiodothyonine -7% of hormone -more potent in blood Calcitonin -Regulates calcium short-term Dependent on iodine for production