URINARY SYSTEM

HST I

SPRING 2010

Anatomy and Physiology

Urinary elimination depends on the function of the:

1. Kidneys

2. Ureters

3. Bladder

4. Urethra

Kidneys• Paired • Reddish-brown color• Bean-shaped • Lie on either side of the vertebral

column• Extend to the 12th thoracic and

third lumbar vertebrae• Left kidney is normally higher than

the right due to the anatomical position of the liver

Kidneys• Waste products of metabolism that collect in

the blood are filtered in the kidneys• Blood reaches the kidneys by a renal artery

that branches from the abdominal aorta• Approximately 20-25% of the cardiac output

circulates daily through the kidneys• Each kidney contains 1 million nephrons

Kidneys• Responsible for maintaining normal Red Blood

Cell (RBC) volume• Produce erythropoietin, a hormone released

primarily from specialized glomerular cells that sense decreased RBC oxygenation

• After being released from the kidney erythropoietin functions within the bone marrow to stimulate erythropoiesis (production of mature RBCs)

Renin• Another hormone produced by the

kidneys

• Major role is the regulation of blood flow in times of renal ischemia (decreased blood supply)

Anatomy of Kidney• Cortex –hard outer layer• Medulla – fleshy portion• Pyramids – triangular

shaped open areas• Nephrons – microscopic

units that make urine.• Renal sinus or pelvis –

collection basin for urine at base of kidney

Nephron• The functional unit of

the kidney, forms urine• Composed of the

glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal tubule, and collecting duct

Glomerulus• Initial site of filtration of the blood and the

beginning of urine formation• The capillaries here are porous and allow

filtration of water and substances such as glucose, amino acids, urea, creatinine, and major electrolytes into the Bowman’s capsule

• Large proteins and blood cells are not normally filter through

Glomerulus• The presence of large

proteins in the urine (proteinuria) is a sign of glomerular injury

• Filters approximately 125ml of filtrate per minute

Bowman’s Capsule• A C-Shaped structure• Surrounds the

glomerulus• Is the start of the

convoluted tubule• Passes the filtered

materials into the convoluted tubule

Tubules• Filtered substances needed

by the body are reabsorbed and returned to the blood through capillaries

• Most of the sugar, water, and salts are reabsorbed

• Urea, uric acid, and creatinine remain in the tubules

Ureters• Tubular structures measuring 25-30cm

in length and 1.25cm in diameter

• Extend from renal pelvis to bladder

• Peristalsis of the muscular layer of the ureter transport urine through this structure

Bladder• Hollow, distendable

muscular sac• Located behind symphysis

pubis • Midline in pelvic cavity• Lined with mucous

membrane• Reservoir for urine,

minimum held usually 300ml

                                                                                                                                                                                                          

                                                            

Urethra• Tube that carries urine from the bladder

outside of the body

• External opening is called the urinary meatus

• Different in male and females

• Normally the turbulent flow of urine washes it free of bacteria

Male Urethra

                                                                                                                                                                                                         

•About 8 inches long •Passes through the prostate gland and through the penis•Carries both urine and semen

Female Urethra

•About 1.5 inches long•Opens in above the vagina•Carries only urine outside the body

Urine• About 1500 to 2000ml (1 1/2 - 2 QTS)

produced daily• 150 Quarts of liquid filtered through

kidneys daily• Made up of concentrated liquid or urea,

uric acid, creatinine, mineral salts, pigments, and 95% water

• Liquid waste product produced by urinary system

Urine Consistency• Normal – clear, straw colored

• Cloudy – white blood cells, pus – infection

• Lighter the color – more water

• Darker the color – more waste

• Pink or red color – blood

Act of Urination• Several brain structures influence

bladder function, including the cerebral cortex, thalamus, hypothalamus, and brainstem

• Together they suppress contraction of the bladder’s muscles until a person wishes to void (urinate)

Act of Urination• The desire to urinate can be sensed when the

bladder contains approximately 150ml of urine• As the volume increases, the bladder walls

stretch, sending sensory impulses to the brain• Impulses from the brain then cause rhythmic

contraction of the bladder muscles• The urethral sphincter relaxes so that urine can

enter the urethra (although voiding does not occur yet)

Act of Urination• As the bladder continues to contract, nerve

impulses travel to the brain making a person conscious of the need to urinate

• If the person chooses not to void, then the external urinary sphincter remains contracted, and the urinary reflex is stopped.

• If the person chooses to void, the external sphincter relaxes, nerve impulses stimulate the bladder to contract, and emptying of the bladder occurs

Diseases and Abnormal Conditions

Cystitis

• Inflammation of the bladder usually caused by pathogens entering the urinary system

Glomerulonephritis

• Inflammation of the glomerulus of the kidney (two types)

• Acute – follows a streptococcal infection

• Chronic – a progressive disease causing scarring and sclerosing of the glomeruli

Pyelonephritis

• Inflammation of the kidney tissue and renal pelvis caused by pyogenic ( pus forming) bacteria

Renal Calculus• A kidney stone

• Formed when salts in the urine precipitate

• Small calculi may be eliminated in the urine, but larger stones often become lodged in the renal pelvis or ureter

Renal Failure

• When the kidneys stop functioning (two types)

• Acute – caused by hemorrhage, shock, injury, poisoning, nephritis, or dehydration

• Chronic – results from progressive loss of kidney function

Uremia

• A toxic condition that occurs when the kidneys fail and urinary waste products are present in the bloodstream.

Urethritis

• An inflammation of the urethra, usually caused by bacteria

Careers

Dialysis Technician

• Operates machines that remove waste and excess fluids from the blood of patients whose kidneys can no longer carry out those functions.

Medical Laboratory Technician

• Works under supervision of a medical technologist or physician to perform test on tissue, blood and body fluids to help physicians diagnose and treat diseases.

Medical Laboratory Technologist

• A health care professional who performs test procedures in laboratories using sophisticated instruments to aid in the diagnosis, prognosis and treatment of diseases.

Nephrologist

• A doctor who is a kidney specialist.

Urologist

• A doctor who specially deals with the urinary system which includes the bladder, the urethra and possibly the ureters.

Key Words

• Bladder – vesicle that acts as the reservoir for the urine

• Bowman’s capsule – part of the renal corpuscle in the kidney; picks up substances filtered from the blood by the glomerulus

• Cortex – the outer section of the kidney

• Excretory system – also known as the urinary system, responsible for removing certain wastes and excess water from the body and for maintaining the body’s acid- base balance

• Glomerulus – microscopic cluster of capillaries in Bowman’s capsule of the nephron in the kidney

• Hilum – a notched or indented area through which the ureter, nerves, blood vessels, and lymph vessels

• Homeostasis – a constant state of natural balance within the body

• Kidneys – bean-shaped organ that excretes urine; located high and in back of the abdominal cavity

• Medulla – the inner section of the kidney; contains most of the collecting tubules which carry the urine from the nephrons

• Nephrons – microscopic filtering units located in the kidneys; consists of a glomerulus, a Bowman’s capsule; a proximal convoluted tubule, a distal convoluted tubule and a collecting duct.

• Renal pelvis – a funnel shaped structure that is the first section of the ureter

• Ureters – tubes that carry urine from the kidneys to the urinary bladder

• Urethra – tube that carries urine from the urinary bladder to outside the body

• Urinary meatus – external opening of the urethra

• Urine – the fluid excreted by the kidney

• Void – to empty the bladder; urinate

Medical Terminology

• Nephritis – inflammation of the kidney

• Nephrohydrosis – disease condition of water in the kidney

• Nephrolithiasis – disease condition of rock/stone in the kidney

Nephro (o) denotes kidney

• Nephropathy – disease of the kidney

• Nephroptosis – falling out/prolapse of the kidney

• Nephrolithotomy – surgical incision to remove rock/stone in the kidney

• Nephrosclerosis – disease condition of hardening of the kidney

• Hydornephrosis – disease condition of water in the kidney

• Nephrostomy – opening/mouth of the kidney

Pyel (o) denotes pelvis of the kidney

• Pyelitis – inflammation of the pelvis of the kidney

• Pyeloscopy – visual examination of the pelvis of the kidney

• Pyelophlebitis – inflammation of the vein and pelvis of the kidney

• Pyelectasis – dilatation of the pelvis of the kidney

• Pyelotomy – surgical incision of the pelvis of the kidney

• Pyelolithotomy – surgical incision to remove rock/stone in pelvis of the kidney

Ur (o)

• Uremia – urea in the blood (toxic condition in the blood)

• Enuresis – in urine (condition of being in urine – bedwetting)

• Diuresis – diluted urine (caused by caffeine and alcohol

• Urinary Incontinence – loss of control of the bladder

• Urinary Retention – can not release urine (blockage)

Uria denotes urine/urea

• Anuria – without urine

• Melanuria – dark/black urine

• Albuminuria – protein in urine

• Hematuria – blood in the urine

• Nocturia – night urine

• Pyuria – pus in the urine

• Oliguria – scanty urine

• Dysuria – bad, difficult, painful urination

Medical Abbreviations

• Mat – maternity

• Med – medicine

• Mg – milligram

• MI – myocardial infarction

• Min – minute

• MN – midnight

• MT – medical technologist

• MOM – Milk of Magnesia

• N – nitrogen

• Na – sodium

• NaCl – salt

• NB – new born

• Neg – negative

• Neur – neurology

• NIH – National Institute of Health

• Nil – none

• No – number

• Noct – night

• NP – nurse practitioner

• NPO – nothing by mouth

• NSY – nursery

• N/V – nausea and vomiting

• NVS – neurological vital signs

Questions