Urinary System W25 PDF

The Urinary System A subsection of the Excretory System Where else does the body (mammalian) excrete things (usually waste things) Sweat Exhaled gases Feces Basic Anatomy Basic Anatomy Kidneys retroperitoneal Right kidney more cranial (except pigs and grasscutters) Visceral...

The Urinary System A subsection of the Excretory System Where else does the body (mammalian) excrete things (usually waste things) Sweat Exhaled gases Feces Basic Anatomy Basic Anatomy Kidneys retroperitoneal Right kidney more cranial (except pigs and grasscutters) Visceral and parietal peritoneum (remember visceral and parietal pericardium?) V = visceral peritoneum P = parietal peritoneum Renal biopsy using laparos copy Basic function of renal system - Homeostasis! Keeping blood (and therefore cells – thinking moment) balanced  Fluid pH Electrolytes Nitrogenous wastes Cleaning the refrigerator Filters blood Reabsorbs good stuff from filtrate Secretes more of other stuff into filtrate that it needs to get rid of Decides how much water to send with filtrate Filtrate  urine  voided A side gig – making hormones Erythropoietin (EPO) Prostaglandins (PGs) Renin (an enzyme actually) – BP regulation through water and sodium retention Also affects and is affected by ADH and aldosterone Gross Anatomy – will discuss in lab Cystotomy in a spa yed female dog (yes that is a spoon) (you will likely have to sign in to Google to watch this surgery) Renal cortex and medulla Porcine kidney Feline kidney Functional unit of the kidney - the nephron Accompanying blood vessels are a very important part of how the kidney functions Renal blood vessels (from Elsevier, Inc. 2016) Renal Vasculature Another view of blood vessels in the kidney Vasa recta Peritubular capillarie Nephron’ s associatio n with the blood stream Vasa recta ------------- > Kidney’s functional unit – the nephron  How th e nephr on work s - short video Creating the concentration gradient i n the medulla - a numbers game Filtration, reabsorption, secretion Renal corpuscle = glomerulus + Bowman’s capsule Glomerulus = ‘nest’ of blood vessels btwn 2 arterioles ( high BP) diam Aff art.>Eff art. Glomerular capillaries have lots of fenestrations Renal blood supply - glomerulus Filtration, reabsorption, secretion Big fenestrations in caps of glomerulus Blood cells and plasma proteins too big to get through Podocytes – make up inner layer of Bowman’s capsule (inner layer =?) Filtration, reabsorption, secretion GFR – mL/min 10 kg dog – 250 mL blood through kidneys each minute Filtration only? 60L of urine per day Glomerular damage? – drugs, diabetes, lupus, infection, toxins, Filtration, reabsorption, secretion Na+, K+, Ca2+, Mg2+, glucose, amino Glomerul ar filtrate Tubular filtrate urine acids, Cl-, bicarbonate, water Osmosis/diffusion Active transport What layers do they have to cross to get back into the bloodstream? Filtration, reabsorption, secretion PCT – 65%, most of Na, Cl, H2O, all Loop of Henle glucose and a.a. Desc permeable to water Sodium actively Ascend. impermeable to water, pumped out via sodium pumped out transport protein Creates salty (hyperosmotic) Glucose and amino medulla acids hitch a ride – passive transport DCT (aka sodium Sodium leaves in exchange for cotransport) H+, NH4+, K+ Potassium diffuses Aldosterone controls this out Collecting Duct Water reabsorbed under the influence of ADH see diagram page 457 Filtration (a), reabsorption (b), secretion (c) If not filtered and still needs to leave body Most in DCT H+, K+, NH3, urea Penicillins and sulfonamide antibiotics Other drugs/toxins Choices for UTIs? What happens in the nephron: Reabsorption (purple) Secretion (orange) Reabsorption and secretion Water regulation (which also affects blood pressure) Anti-diuretic hormone (ADH) – opens water pores in the collecting ducts (ADH made in hypothalamus, stored in posterior pituitary) Aldosterone – increases sodium reabsorption in DCT and collecting duct – sodium moves out of tubules  water follows (if ADH present) – aldosterone is made by adrenal gland Blood Pressure MD homeostasis Juxtaglomerular cells – mostly on afferent arteriole (green) monitor BP, secrete renin if needed (i.e. if BP falls) Macula densa (orange) – specialized cells in ascending thick L of H where meets DCT monitor sodium concentration of filtrate MD cells release prostaglandins, vasodilate afferent art. > efferent art. AND tell JG cells to release renin Macula densa and JG apparatus MD – senses decreased Na+ flowing by (indicates MD cells release prostaglandins, vasodilate afferent art. > efferent GFR, and BP) art. AND tell JG cells to release renin Blood Pressure homeostasis – renin angiotensin-aldosterone system (RAAS) JG cells monitor Renin converts BP – if detect low JG cells release angiotensinogen BP OR MD RENIN  angiotensin I detects less Na Arteries constrict angiotensin I  and aldosterone angiotensin II via and ADH Blood pressure ACE (angiotensin released to increases converting enzyme) increase H20 reabsorption Blood Pressure homeostasis RAAS - simplified High blood pressure? Heart overworked? There’s a drug for that! ACE inhibitors (eg. benazepril) slide 35 Signs you are giving too much? Loop diurectics (eg. furosemide) slide 29 Ureters Transitio Fibrous layer Smooth muscle nal epitheliu lumen m Ureters Peristalsis – continuous Enter ur. bladder obliquely so no back flow Ectopic ureters Urinary Bladder Stores urine Muscular sac Neck Trigone – arrangement of openings of ureters into bladder and opening from bladder into urethra Epithelial lining? Urinary Bladder 3 layers of smooth muscle (like the stomach) Detrusor muscle Empty bladder is round and sits in pelvic canal As it fills, becomes pear shaped and extends cranially into abdominal cavity Micturition Urine accumulates External sphincter at Stretch receptors neck of bladder – fire skeletal muscle Spinal reflex send Brain sends inhibitory motor signal to signals to detrusor detrusor muscle muscles and external sphincter until ready Sensation of “gotta It will eventually relax go pee” if bladder full enough Internal sphincter Sphincters open  relaxes – smooth muscle detrusor muscle activated Nervous control of micturition Urethra Female Male Short, straight Longer, curved (cat?) Opens on floor of Runs along ventral vestibule of vulva aspect of penis Transitional Shared with epithelium reproduction system (carries urine and semen) Transitional epithelium (ish) Kidney Disease Acute vs. chronic Lateral abdominal radiograph of a dog Feline lateral radiograph Canine lateral radiograph with bladder stones (uroliths) IV pyelogram Cystoscopy http://tv.doccheck. com/com/movie/14 41/cystoscopy-blad der-dog