Urinary System

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Urinary System The body produces urine as a way to get rid of waste and extra water that it doesn't need. Before leaving your body, urine travels through the urinary tract, which consists of: Kidneys Ureters Bladder Urethra urinary meatus meatus

Structures of the Urinary System Outside opening

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Kidneys filter waste from the blood and produce urine, they are: Bean-shaped organs Located between peritoneum and the back muscles (RETROPERITONEAL) Held in position by connective tissue Enclosed in an adipose capsule Protected by the ribs

Structures of the Urinary System Ureters- two thin tubes that take urine from the kidney to the bladder Smooth muscle tube with mucous Membrane lining Peristalsis pushes urine down ureters Ureters

Structures of the Urinary System Urinary bladder - Hollow muscular organ located in pelvic cavity that holds urine until it's time to urinate - Made of elastic fibers and involuntary muscles - Stores urine- usually about 500cc - Emptying urine (voiding) is involuntary but controlled through nervous system (voluntary) Function = store and aid in elimination of urine

Structures of the Urinary System Urethra- the tube that carries urine from the bladder out of the body when you urinate (micturate or void) Connects the bladder to the outside of the body Female 1-2” long Male 4-6” long

Structures of the Urinary System Urinary meatus – Opening to the outside of the body where urine leaves through

Watch Youtube Video The Kidneys...https://youtu.be/_NO8n48AKJY

Structure of Kidneys: External kidney Renal fascia Renal Hilum Fibrous layer of connective tissue Renal Hilum Indentation that gives the kidney its bean-shaped appearance

Structure of Kidneys: Internal kidney consists of:                                                                                                                         Internal kidney consists of: Renal cortex - Outer layer – Composed of millions of microscopic functional units called nephrons Renal medulla - Middle layer- Contains RENAL PYRAMIDS Base of each pyramid faces cortex, while apex empties into cuplike cavities called CALYCES - and contains Renal columns located between the pyramids. Renal pelvis - Innermost layer -funnel shaped structure at the beginning of the ureter (funnels all the Urine into the ureters)

Label Kidney: Hilum

Label Kidney: Hilum

What if kidneys are not working properly? Toxic wastes would accumulate in the cells, suffocating and poisoning them.

Function of Urinary System Excretion- removing nitrogenous wastes, certain salts and excess water from blood Formation of urine Maintain acid-base balance (fluid & electrolyte balance) Elimination of Urine (Secrete waste products in the form of urine – remove waste from body)

Structure of Kidneys:                                                                                                                         Internal kidney, cont. The nephron is the tiny filtering structure in your kidneys.   Each of your kidneys contain more than a million tiny filtering nephrons that help clean your blood.

Nephron structure Nephron is the Functional unit of kidney Afferent arteriole – blood from renal artery enters through this… Nephron is the Functional unit of kidney Consists of Renal Corpuscle & Renal Tubules…….

Nephrons Functional unit of the kidney Over 1 million in each kidney which comprise 140 miles of filters and tubes Parts include: Bowman’s capsule Glomerulus Proximal convoluted tubule Loop of Henle Distal convoluted tubule Collecting tubule

Nephron structure Renal corpuscle consist of: Bowman’s capsule-double-walled hollow capsule – it surrounds glomerulus Bowman’s capsule filters out 125cc of fluid/min. …how many cc’s per hour is this? As the filtrate continues through nephron, 90% of water is reabsorbed—what would happen if reabsorption here failed? & Glomerulus-knotty ball formed from afferent arterioles finely dividing – contains 50 separate capillaries

Nephron structure cont’d Proximal convoluted tubule- twisted tubular branch off Bowman’s capsule Loop of Henle – proximal convoluted tubule descends into the medulla forming large loop Distal convoluted tubule – ascending limb of Henle’s loop Collecting tubule – distal tubule opens into collecting tubule

Nephron structure

Nephron structure Glomerulus Loop of Henle Collecting Tubule Ureter Bowman’s Capsule Proximal Convoluted Tubule Distal Convoluted Tubule Glomerulus Loop of Henle Collecting Tubule Ureter

Watch Youtube Video The Urinary System… https://youtu.be/OkyFPMXa28c

Order of Urine Formation in the Nephron 1- Filtration 2. Reabsorption 3- Secretion

Filtration First step in urine formation Blood from renal artery enters glomerulus High blood pressure in glomerulus forces fluid (Filtrate) to filter into Bowman’s capsule (function of glomerulus is to filter substances from the blood) Filtrate does not contain plasma proteins or RBCs- they are too big Bowman’s capsule filters out 125cc of fluid/min. – 7500cc/hour As filtrate continues through nephron, 90% of water is reabsorbed

Reabsorption Water and useful substances are reabsorbed in proximal convoluted tubule to stay in the body If blood levels of certain substances are high (glucose, amino acids, vitamins, sodium) then those substances will not be reabsorbed Useful substances filter out of the renal tubules and back into the capillaries around the tubules = reabsorption . How does this help maintain homeostasis?

Secretion Opposite of reabsorption Secretion transports substances from blood into collecting tubules to leave the body Substances include creatinine, hydrogen ions, potassium ions, and some drugs Electrolytes are selectively secreted to maintain body’s acid-base balance

Watch Youtube Video Urine Formation... https://youtu.be/oCQ-5iwTQvM

Urinary Output Average= 1500 ml/day Urinalysis- examination of urine to determine presence of blood cells, bacteria, acidity level, specific gravity and physical characteristics (color, clarity and odor) Normal in urinalysis = Ammonia not normal = glucose, blood, pus

Urinary Output If more water is reabsorbed back into the body---what will happen to urine concentration? (more or less concentrated?)

Path of urine formation Afferent arteriole - Glomerulus – Bowman’s capsule – proximal convoluted tubule – loop of Henle – distal convoluted tubule – collecting tubule – renal pelvis - ureter

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Urine formation is controlled by Chemical Control (ADH & Aldosterone) & Nervous Control

Chemical Control Reabsorption of H2O in distal convoluted tubule The amount of ADH produced is related to the level of body hydration Reabsorption of H2O in distal convoluted tubule controlled by ADH (antidiuretic hormone) Secretion and regulation of ADH controlled by hypothalamus Aldosterone release is the result of the renin-angiotensin system. Diuretics inhibit reabsorption of H2O Medications can replace chemicals created by body i.e. renin = diuretic Production of urine is controlled by ADH and Aldosterone

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Nervous Control Direct control through nerve impulses on kidney blood vessels Indirect control through stimulation of endocrine glands

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Disorders of the Urinary System Renal Calculi (Kidney Stones) “Calc” means “stone” Also known as nephrolithiasis (nephro lith iasis) “Lith” means “stone” Made of crystals of calcium phosphate and uric acid Gradually they get larger until they block ureters…can cause hydronephrosis First symptom- severe pain Other symptoms- nausea and vomiting, frequency, chills, fever, hematuria Diagnosis- by symptoms, ultrasound, or x-ray Rx- increase fluids to flush out stone, medications, and if needed- lithotripsy

Lithotripsy Surgical procedure to remove kidney stones                                         Surgical procedure to remove kidney stones Shock waves hit dense stones and break them up Done on outpatient basis

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Nephritis “nephr” means “kidney” “itis” means “inflammation” Inflammation of the kidney (kidney infection)

Incontinence = Involuntary urination

Updated July 29, 2005        Cystitis (cyst= medical term for ____ + itis =___ ) Inflammation of the mucous membrane lining of the urinary bladder Most common cause- E. Coli Symptoms- Dysuria (painful urination), lower abd pain, and frequency Usually in females (shorter urethra) Rx- antibiotics

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Dialysis (Hemodialysis) Used for kidney failure Involves the passage of blood through device with semipermeable membrane Dialysis serves as substitute kidney… replaces filtration Blood from patient flows through machine and is filtered Can be done at home or in clinic Takes 2-4 hours, 2-3 times a week

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Glomerulonephritis - group of diseases that injure the part of the kidney that filters blood (called glomeruli).  When the kidney is injured, it cannot get rid of wastes and extra fluid in the body. If the illness continues, the kidneys may stop working completely, resulting in kidney failure. Acute - develops suddenly. You may get it after an infection in your throat or on your skin or some diseases. Sometimes, you may get better on your own. Other times, your kidneys may stop working unless the right treatment is started quickly. Chronic - Sometimes, the disease runs in the family. This kind often shows up in young men who may also have hearing loss and vision loss. Some forms are caused by changes in the immune system. However, in many cases, the cause is not known. Sometimes, you will have one acute attack of the disease and develop the chronic form years later.

Glomerulonephritis Acute & Chronic Watch Youtube Video Glomerulonephritis Acute & Chronic https://youtu.be/64Xuw1hz5HY

Chronic: gradual loss of function of the nephrons Renal Failure Acute: may be sudden onset-causes may be nephritis, shock, injury, bleeding, sudden heart failure or poisoning. Sx: oliguria (scanty amt urine), anuria (absence of urine) Chronic: gradual loss of function of the nephrons

Watch Youtube Video The Kidneys... https://youtu.be/Kixqn8i9MN4

Kidney Transplant As a last resort Involves donor organ from someone with a similar immune system Main complication- rejection

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Terminology Enuresis- bedwetting Incontinence – involuntary urination Gylcosuria- sugar in urine Nocturia- frequent urination at night Polyuria- large amounts of urine Anuria- no urine produced Hematuria- blood in urine Diuretic- drug or substance to increase urine production Oliguria – decreased urine production (sign of kidney failure)