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Urinary System

Urinary System. Lecture 19 Bio11. Urinary System Functions Control of blood Volume Composition Electrolyte, pH balance removal of metabolic wastes (ammonia, urea) other substances System to conduct wastes out of body. Adrenal Glands. Kidneys – filter blood. Ureters.

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Urinary System

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  1. Urinary System Lecture 19 Bio11

  2. Urinary System Functions • Control of blood • Volume • Composition • Electrolyte, pH balance • removal of metabolic wastes (ammonia, urea) • other substances • System to conduct wastes out of body

  3. Adrenal Glands Kidneys – filter blood Ureters Urinary Bladder Urethra

  4. Kidney Structure • Retroperitoneal = ? • Covered by: _________________ • Renal cortex – __________________ • Renal medulla – __________________ • Renal pelvis – gathering area of __________ • connects to ___________ • Basic functional unit of kidney: __________ ~ 1 million/kidney – in pyramids • 2 types

  5. Nephrons – Functional Units of Kidneys • Two basic parts: 1. Renal corpuscle -initial filtrate collected from the glomerulus Glomerulus: knot of capillaries Glomerular (Bowman’s) capsule – cuplike 2. Renal tubule – 3 parts – selective reabsorption/secretion Proxumal convuluted tubule Loop of Henle Distal convoluted tubule

  6. Blood Supply to Nephron • afferent arterioles enter glomerulus • efferent arteriole carries blood from glomerulus • smaller diameter creates some blood pressure in glomerulus • branches form peritubular capillary system • blood leaves peritubular capillary system via renal veins • juxtaglomerular apparatus • area of close contact between distal convoluted tubule and afferent/efferent convoluted tubules

  7. Urine • Formed by action of Nephrons • Concentrated (hypertonic) – water is conserved • Metabolic wastes • Drugs (antibiotics, etc.) • Excess nutrients + salts not reabsorbed

  8. Urine formation – 3 steps 1. Filtration – renal corpuscle water + dissolved substances 2. Tubular reabsorption – proximal tubule 3. Tubular secretion – proximal/distal tubules

  9. Urine Formation • Glomerular filtration • initial filtrate contains all blood components except: • formed elements • most proteins • Tubular reabsorption • 99% of material reabsorbed: • glucose, amino acids, ions, water • Tubular secretion • secretion to peritubular capillaries of: • ions: K+, H+, NH4+ • creatine • drugs: (penicillin, sulfa drugs)

  10. Regulation: Three Hormones • Justaglomerular apparatus  renin  angiotension II – what is effect? • Antidiuretic hormone - (ADH) – from ? • Function ? • Aldosterone from adrenal glands • inc. reabsorption of Na+ thus water reabsorption • Caffeine impacts by reduction of Na+ reabsorption • Atrial natriuretic peptide (ANP) • Released by heart - stretching • reduces blood pressure by decreasing vloume – how?

  11. Declining blood pressure Juxtaglomerular cells release renin Angiotensin II produced Constriction of blood vessels – pressure rises Thirst – inc. blood volume Aldosterone release – inc. Na+ + water reabsorption Antidiuretic hormone release – inc. water reabsorption

  12. Impact of Kidneys on Blood pH • Background: pH of blood regulated through • Kidneys • Respiration (CO2 enters blood) • Buffering system of blood • Kidney’s Role – acid blood condition (reverse if not the case): • Secretion of excess H+ • Resupply bicarbonate to blood

  13. Kidneys Functions – Summary • Waste removal/Water conservation – Urine formation • Regulate • Blood pressure • Osmotic conditions • pH • Red blood cell formation – erythropoietin • Transform vitamin D into active form: calcitrol

  14. Urinary Tract and related Issues • Urinary Bladder • Urethra • Micturition

  15. Impaired Kidney Function • Acute – rapid onset • from severe inflammation or ingestion of poison • Chronic – progressive and long term (months/years) • decline in nephron function (may be genetic as polycystic disease)

  16. Consequences • acidosis • Anemia (failure to produce erythropoietin) • Edema • Hypertension • Accumulation of nitrogenous wastes • Dialysis - Kidney transplant

  17. Control of Urination • Involuntary – • Stretch receptors in bladder • Signal to lower spine • Signal to brain/detrusor muscle/internal sphincter • Voluntary • Control of external sphincter

  18. Urinary System Issues • Kidney failure – disease • Incontinence - failure of urination control • Kidney stones – mineral formation • Infection – bacterial • Extra issue in females – length of urethra • Progressive: urethritis/cystitis/pyelonephritis

  19. The End.

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