Exam 5: Adrenal Corticosteroid Part 1 Flashcards
What is the definition of hormone?
- Chemical regulators of cellular function
- Synthesized in specific cells in endocrine glands
- Released in circulation
- Acts on specific target tissues in specific target receptors
- Effects are of physiologic importance to the organism
What are examples of amino acid based hormones?
Insulin, GH, catecholamines
What are eicosanoids?
Locally secreted, locally acting hormones (prostaglandins)
What are examples of steroid derivatives of cholesterol?
Adrenocortical hormones (cortisol, aldosterone)
Gonadal (testosterone, estrogen)
What are the target cells of hormone action?
Receptors in plasma membranes (GPCR)
Intracellular receptors (cytoplasmic or nuclear)
What are the types of intracellular receptors?
- Direct nuclear gene activation or suppression)
- Used by steroids and thyroid hormones (lipid soluble)
Describe the membrane receptor mechanism for steroids?
- Hormone diffuses through plasma into cytosol
- Binds to intracellular or nuclear receptor to form hormone-receptor complex
- Hormone-receptor complex in the nucleus interacting with chromatin to affect gene transcriptional activity
- Transcription of mRNA
- Synthesis or translation of protein
What are the properties of steroid hormones?
- Synthesized and immediately released
- Derived from cholesterol
- Enzymes produce steroid hormones from cholesterol in the mitochondria and SER
- Lipid soluble and freely permeable in membranes
- Carried in blood by globulins
- Secreted by one cell and converted to the active steroid by target cell
What globulin carries cortisol?
Corticosteroid binding globulin
What globulin carrie estradiol and testosterone?
Sex steroid binding globulin
What are examples of a steroid that is converted to an active steroid?
- Androgens secreted by the gonads converts to estrogen in the brain
- 5-alpha-reductase in the prostate converts testosterone to DHT
What are the important roles of steroid hormones and what are the examples associated with the roles?
- Carbohydrate regulation (glucocorticoid)
- Mineral balance (mineralocorticoids)
- Reproductive functions (gonadal steroids)
What are the important roles of glucocorticoids?
- Inflammatory responses
- Stress responses
- Bone metabolism
- Cardiovascular fitness
- Behavior
- Cognition
- Mood
What is the purpose for the hypothalamus?
- Neurosecretory hormone secreting cells of the posterior pituitary via infundibular stalk
- Releasing and inhibitory factors that act on cells in the anterior pituitary via hypophyseal portal system
What is the purpose the pituitary?
- Cells that produce hormones release them into the bloodstream
What is the posterior pituitary?
Comprised of the endings of axons from cell bodies in the hypothalamus
What are the principal hormones of the posterior pituitary and where are they secreted?
- Vasopressin (ADH): kidneys for water reabsorption
- Oxytocin: Mammary glands of milk ejection and uterus for uterine contraction
What connects the hypothalamus to the pituitary?
Converging blood vessels (median eminence) in the hypophyseal portal system
What is secreted by the hypothalamus?
Releasing and inhibitory hormones
What are releasing hormones?
Released by the hypothalamus that cause the release of hormones by the anterior pituitary
What are inhibitory hormones?
Released by the hypothalamus that inhibit secretion of hormones by the anterior pituitary
What is ACTH (Adrenocortiotropic hormone)?
Stimulates cortisol secretion in the adrenal cortex
What is growth hormone?
Primary hormone responsible for regulating body growth and important for metabolism
What is prolactin?
Females: stimulates breast development and milk production
Males: Testicular function
What is TSH (thyroid stimulating hormone)?
Stimulates the secretion of thyroid hormone and growth of thyroid gland
What is FSH (follicle stimulating hormone)?
F: stimulates growth and development of ovarian follicles promoting secretion of estrogen by ovaries
M: Sperm production
What is LH (luteinizing hormone)?
F: Ovulation, formation of corpus lutes in ovary, regulation of ovarian secretion
M: Stimulates cell in testes to secrete testosterone
What is CRF or CRH (corticotropin releasing factor/hormone)?
Regulates ACTH secretion from anterior pituitary; cortisol release to blood
What is ACTH (adrenocorticotropin hormone)?
Regulates glucocorticoid (cortisol) secretion from adrenal gland
What are the feedback loops for cortisol secretion?
- ACTH inhibits CRH
- Cortisol inhibits CRH and ACTH
What is hyposecretion?
Too little hormone produced -> less than normal response
What is hypersecretion?
Excess of hormone produced -> exaggeration of normal effect
What is an example of primary pathology with the endocrine systems?
Damage to the hormone secreting gland such as tumor, death to cells, or autosomal abnormalities
What is an example of secondary pathology with the endocrine systems?
Damage to control mechanisms of glands
What is abnormal tissue responsiveness?
Receptor defect or resistance caused by mutations in receptors or second messenger pathways
What is a common cause of hyperpituitarism?
Adenoma