Structures of the Urinary System  Kidneys  Ureters  Bladder  Urethra  Urinary meatus

Structures of the Urinary System

Kidneys  Bean-shaped organs  Located between peritoneum and the back muscles (RETROPERITONEAL)  Held in position by connective tissue connective tissue  Enclosed in an adipose capsule capsule  Protected by the ribs

Structures of the Urinary System Ureters- The tubes that connect the kidneys and bladder. the kidneys and bladder.  Muscular tube extending from each kidney to the urinary bladder  Lined by a mucous membrane  10-12” long  One from each kidney  Carry urine from kidney to 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  Made of elastic fibers and involuntary muscles 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-_______  Connects the bladder to the outside of the body  Female 1-2” long  Male 4-6” long  Urine leaves through urethra to outside opening = Urinary Meatus

Structures of the Urinary System Urinary meatus  Opening to the outside of the body

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

Structure of Kidneys: Structure of Kidneys: Internal kidney Internal kidney consists of: consists of:  Renal cortex - Outer layer  Renal medulla - Middle layer  Renal pelvis - Innermost layer-

Structure of Kidneys: Structure of Kidneys: Internal kidney  Renal cortex -Outer layer -Composed of millions of microscopicfunctional units called nephrons

Structure of Kidneys: Structure of Kidneys: Internal kidney Internal kidney Renal medulla  Middle layer striated layer  Contains RENAL PYRAMIDS (the striated cones) (the striated cones)  Base of each pyramid faces cortex, while apex empties cortex, while apex empties into cuplike cavities called into cuplike cavities called CALYCES CALYCES  Renal columns  Located between the pyramids the pyramids  Cortical tissue

Structure of Kidneys: Internal kidney  Renal pelvis - Innermost layer- funnel shaped structure at funnel shaped structure at the beginning of the the beginning of the ureter (funnels all the ureter (funnels all the Urine into the ureters) Urine into the ureters)

Label Kidney: Hilum

Label Kidney: Hilum

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

Function of Urinary System 1.Excretion- removing nitrogenous wastes, certain salts and excess water from blood 2.Formation of urine 3.Maintain acid-base balance (fluid & electrolyte balance) 4.Elimination of Urine (Secrete waste products in the form of urine – remove waste from body)

Nephrons  Functional unit of the kidney  Over 1 million in each kidney which comprise 140 miles of filters and tubes  Parts include: 1.Bowman’s capsule 2.Glomerulus 3.Proximal convoluted tubule 4.Loop of Henle 5.Distal convoluted tubule 6.Collecting tubule

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

Nephron structure Renal corpuscle consist of: 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? …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 is reabsorbed—what would happen if reabsorption herefailed? &  Glomerulus-knotty ball formed from afferent formed from afferent arterioles finely dividing 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

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

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

Filtration First step in urine formationFirst step in urine formation Blood from renal artery enters glomerulusBlood 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)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 bigFiltrate does not contain plasma proteins or RBCs- they are too big Bowman’s capsule filters out 125cc of fluid/min. – 7500cc/hourBowman’s capsule filters out 125cc of fluid/min. – 7500cc/hour As filtrate continues through nephron, 90% of water is reabsorbedAs 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 from blood into collecting tubules to leave the body to leave the body  Substances include creatinine, hydrogen ions, potassium ions, hydrogen ions, potassium ions, and some drugs and some drugs  Electrolytes are selectively secreted to maintain body’s acid-base balance secreted to maintain body’s acid-base balance

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

Chemical Control  Reabsorption of H2O in distal convoluted tubule controlled by ADH (antidiuretic hormone) 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 ADH The amount of ADH produced is related to the level of body hydration

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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) 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  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) kidney (kidney infection)

Incontinence = Incontinence =  Involuntary urination

Cystitis  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 Updated July 29, 2005 (cyst= medical term for ____ + itis =___ )

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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 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 -  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 -  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.

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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) Sx: oliguria (scanty amt urine), anuria (absence of urine)  Chronic: gradual loss of function of the nephrons

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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)