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Kidney regulation: hormones. Antidiuretic hormone (ADH) ~ secretion increases permeability of distal tubules and collecting ducts to water (H2O back to body); inhibited by alcohol and coffee
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Kidney regulation: hormones • Antidiuretic hormone (ADH) ~ secretion increases permeability of distal tubules and collecting ducts to water (H2O back to body); inhibited by alcohol and coffee • Juxtaglomerular apparatus (JGA) ~ reduced salt intake--->enzyme renin initiates conversion of angiotension (plasma protein) to angiotension II (peptide); increase blood pressure and blood volume by constricting capillaries • Angiotension II also stimulates adrenal glands to secrete aldosterone; acts on distal tubules to reabsorb more sodium, thereby increasing blood pressure (renin-angiotension-aldosterone system; RAAS) • Atrial natriuretic factor (ANF) ~ walls of atria; inhibits release of renin, salt reabsorption, and aldosterone release
Chemical Signals in Animals Without hormones, what would we be like? 2
Hormones Are Specific • Hormone~ chemical signal secreted into body fluids (blood) communicating regulatory messages • Target cells~ body cells that respond to hormones 3
Glands and Cells • Endocrine system/glandshormone secreting system/glands (ductless) • exocrine glands secrete chemicals (sweat, mucus, enzymes) through ducts • Neurosecretory cells~ actual cells that secrete hormones 4
Regulatory Systems • Feedback regulation is a feature of both the endocrine and nervous systems. • Negative feedback regulates many endocrine and nervous mechanisms. 5
Local regulators: cells adjacent to or near point of secretion • Growth factors ~ proteins for cell proliferation • Nitric oxide (NO) ~ neurotransmitter; cell destruction; vessel dilation • Prostaglandins ~ modified fatty acids secreted by placenta and immune system; also found in semen 6
Explain the difference between these two modes of signaling: 7
Mode of Action: Chemical Signaling • 1- Plasma membrane reception • signal-transduction pathways (neurotransmitters, growth factors, most hormones) • 2- Cell nucleus reception • steroid hormones, thyroid hormones, some local regulators 8
Vertebrate Endocrine System • Tropic hormones ~ a hormone that has another endocrine gland as a target • Hypothalamus~pituitary • Pituitary gland • Pineal gland • Thyroid gland • Parathyroid glands • Thymus • Adrenal glands • Pancreas • Gonads (ovary, testis) PRACTICE!! 11
The hypothalamus & pituitary • Hypothalamus- Releasing and inhibiting hormones • Anterior pituitary: • Growth (GH)~bones gigantism/dwarfism acromegaly • Prolactin (PRL)~mammary glands; milk production • Follicle-stimulating (FSH) & • Luteinizing (LH)~ovaries/testes • Thyroid-stimulating (TSH)~ thyroid • Adrenocorticotropic (ACTH)~ adrenal cortex • Melanocyte-stimulating (MSH) • Endorphins~natural ‘opiates’; brain pain receptors 12
The pituitary, II The posterior pituitary: Oxytocin~ uterine and mammary gland cell contraction Antidiuretic (ADH)~ retention of water by kidneys 13
The pineal, thyroid, & parathyroid Melatonin~ pineal gland; biological rhythms Thyroid hormones: Calcitonin - lowers blood calcium Thyroxine - metabolic processes Parathyroid (PTH)~raises blood calcium 14
The pancreas Islets of Langerhans Alpha cells: •glucagon~ raises blood glucose levels Beta cells: •insulin~ lowers blood glucose levels Type I diabetes mellitus (insulin-dependent; autoimmune disorder) Type II diabetes mellitus (non-insulin-dependent; reduced responsiveness in insulin targets) 15
Adrenals 16
The adrenal glands Adrenal medulla (catecholamines): •epinephrine & norepinephrine~increase basal metabolic rate (blood glucose and pressure) Adrenal cortex (corticosteroids): •glucocorticoids(cortisol)~raise blood glucose •mineralocorticoids (aldosterone)~reabsorption of Na+ and K+ 17
Adrenals • Top of kidney • Cortex- from mesoderm • mineralcorticoids control water and electrolyte balance (Na+ and K+). • glucocorticoids (ACTH) control cortisol, corticosterone, and cortisone which promotes normal metabolism • Cannot live without the Cortex 18
Adrenals cont…. • Medulla from ectoderm • Epinephrine=adrenaline • Isolated by Japanese chemist Jokichi Takamine • Prepared synthetically, formerly from adrenal glands • Stimulates heart, constricts small blood vessels, raises blood pressure, converts glycogen to glucose in liver • Norepinephrine=noradrenalin, same as neurotransmitter from autonomic nerves • Mimics sympathetic nerves • Can live without medulla • Can be removed 19
The gonads Steroid hormones: precursor is cholesterol androgens (testosterone)~ sperm formation; male secondary sex characteristics; gonadotropin estrogens (estradiol)~uterine lining growth; female secondary sex characteristics; gonadotropin progestins (progesterone)~uterine lining growth 20
Dwarfism 25
Agromegaly 26
Growth Hormone=HGH • restores muscle mass • decreases body fat • increases sexual function • thickens the skin reducing wrinkles • restores lost hair • restores hair color • Increases energy • improves cholesterol profile • Improves vision • improves memory • elevates mood and improves sleep • normalizes blood pressure • increases cardiac output and stamina 27