Hypothalamus and Pituitary gland Flashcards
Chemical messengers that regulate target cells; produced at one site, act at distant sites
Hormones
Type of hormones: Water-soluble, no carrier protein
Proteins/Peptides
Examples of glycoproteins
FSH, LH, TSH, hCG
Examples of polypeptides
ACTH, GH, PRL, ADH, oxytocin, PTH, calcitonin, insulin, glucagon, gastrin
Type of hormones: Synthesized from cholesterol, lipid-soluble, require carrier protein
Steroids
Examples of adrenocortical hormones
Cortisol, Aldosterone, DHEA
Examples of gonadal hormones
Estrogens, Progesterone, Testosterone
Type of hormones: Synthesized from tyrosine
Amines
Thyroid hormones: Behavior and half-life
Behave like steroids; half-life 7-10 days
Catecholamines: Behavior and half-life
Behave like protein hormones; half-life <1 minute
Examples of amine hormones
Thyroxine (T4), T3, Epinephrine, Norepinephrine
Type of feedback where a releasing factor stimulates pituitary hormones
Positive feedback
Type of feedback where target hormone inhibits pituitary and hypothalamus hormones
Negative feedback
HPT axis sequence of stimulation
Hypothalamus -> TRH -> Pituitary gland -> TSH -> Thyroid gland -> T3/T4
Hormonal change in disrupted negative feedback
Elevated T3/T4 leading to inhibition of TRH and TSH secretion
Defect in target organs like adrenal cortex, thyroid, or gonads
Primary disorder
Defect in anterior pituitary causing hormonal imbalance
Secondary disorder
Rare defect in the hypothalamus affecting hormone secretion
Tertiary disorder
Examples of tropic hormones in the HPT axis
FSH, LH, ACTH, TSH
Stimulatory feedback process in thyroid hormone production
Hypothalamus -> TRH -> Anterior Pituitary -> Thyroid -> T4/T3 production
Feedback process where T3/T4 inhibits anterior pituitary and hypothalamus
Negative feedback
Function of the hypothalamus in hormone regulation
Stimulates pituitary glands and regulates its secretions
Hormone from hypothalamus that stimulates ACTH secretion
Corticotropin-releasing hormone (CRH)
Hormone from hypothalamus that stimulates FSH and LH secretion
Gonadotropin-releasing hormone (GnRH)
Hormone from hypothalamus that stimulates GH secretion
Growth hormone-releasing hormone (GHRH)
Hormone from hypothalamus that stimulates TSH secretion
Thyrotropin-releasing hormone (TRH)
Hormone from hypothalamus that inhibits prolactin secretion
Dopamine (Prolactin Inhibiting Factor, PIF)
Hormone from hypothalamus that inhibits GH and TSH secretion
Somatostatin
Releasing hormone that stimulates adrenal gland targeting ACTH secretion
Corticotropin-releasing hormone (CRH)
Releasing hormone that stimulates FSH and LH secretion
Gonadotropin-releasing hormone (GnRH)
Inhibitory hormone that blocks prolactin secretion from pituitary gland
Dopamine (PIF)
Role of somatostatin in hormone regulation
Inhibits GH and TSH secretion
Role of the pituitary gland in the endocrine system
Master gland that distributes commands to other tissues
Type of signal interpreted by the pituitary gland from the hypothalamus
GnRH (gonadotropin-releasing hormone)
Feedback type where stimulation is successful
Positive feedback
Feedback type indicating unsuccessful regulation
Negative feedback
Pathway from hypothalamus to thyroid hormone production
Hypothalamus (releases) -> TRH -> Pituitary gland (Stimulates)-> TSH -> Thyroid gland -> T3/T4