Hormones 1

what are hormones

signaling molecules secreted into the blood

hormones can only exert effect on…

cells with receptors for that hormone

this body system is slower and typically exerts more sustained and long-lived effects; very important for homeostasis

endocrine

steps to how hormones cause effect at the physiological level

1. bind to receptors

2. activated receptors initiate signaling pathway; modulates gene expression or enzyme activity

3. changes the function of cells which results in physiological outcome

3 categories of hormones

protein and peptide, amine, steroid

protein and peptide hormones are translated into proteins by

ribosomes

examples of protein and peptide hormones

hypothalamic, pituitary, insulin

how to protein and peptide hormones reach adjacent capillaries

packaged into vesicles and secreted by exocytosis

peptide hormones that are translated as larger proteins and cleaved into smaller peptides

insulin and ADH

where are amine hormones derived from

amino acids

examples of amine hormones

epinephrine, norepinephrine, T3 and T4

how do amine hormones reach adjacent capillaries

packaged and stored in vesicles and then secreted by exocytosis when needed

most peptide and amine hormones are ______ so they cannot diffuse across the plasma membrane and must ______

polar and/or charged; bind extracellular receptors

what do bound extracellular receptors do

activate gene expression or modulate activity of enzymes

the only non-polar amine hormones

thyroid hormones T3 and T4

what makes T3 and T4 mostly non-polar

iodine

how do thyroid amine hormones behave differently to other amine hormones

bind intracellular receptors

where are steroid hormones derived from

cholesterol

examples of steroid hormones

aldosterone, cortisol, vitamin d, testosterone, estradiol

effects of steroid hormones being small and non-polar

easily diffuse across membranes and are made on demand

which two hormone types bind to intracellular receptors

steroids and thyroid hormones T3 and T4

what do bound intracellular receptors do

bind to DNA to activate the expression of genes that encode proteins

what do the hypothalamus and pituitary gland secrete

peptide hormones

what are neurohormones and where do they come from

secreted by hypothalamus; released by neurons into the bloodstream. some are effector hormones, some are stimulatory hormones

what gland is the hypothalamus connected to

pituitary

posterior pituitary

where neurons of the hypothalamus secrete oxytocin and ADH (effector neurohormones)

anterior pituitary

secretes hormones in response to stimulatory neurohormones from the hypothalamus

the ____ ____ is like an extension of the hypothalamus

posterior pituitary

what type of hormones are ADH and oxytocin

effector peptide neurohormones

what does ADH do

increases the reabsorption of water in the kidneys → increases blood volume and BP

what does oxytocin do

stimulates contraction of smooth muscle in uterus and mammary glands

neurohormones important for pair bonding

oxytocin and ADH

release of hormones by the anterior pituitary gland is controlled by the

hypothalamus

releasing neurohormones

secreted by hypothalamus to stimulate cells of the anterior pituitary

hormones of the anterior pituitary

• TSH (thyroid stimulating hormone): stimulates thyroid to produce T3 and T4

• gonadotropic hormones (FSH and LH): stimulate gonads to secrete s3x hormones and stimulates gamete production

• GH (growth hormone): stimulates liver to secrete IGF-1 and stimulates muscular and skeletal growth

• ACTH (adrenocorticotropic hormone): stimulates adrenal cortex to secrete cortisol

• Prolactin: stimulates milk production in mammary glands

most anterior pituitary hormones are (stimulatory or effector)

stimulatory (TSH, FSH and LH, GH, ACTH)

what are the effector anterior pituitary hormones

prolactin, GH, gonadotropic hormones

what kind of feedback does each effector hormone exert on the hypothalamus and anterior pituitary

negative

process of negative feedback being exerted on hypothalamus and anterior pituitary by effector hormones

inhibits secretion of releasing hormone → effector hormone levels begin to decrease → negative feedback is relieved