3 things the urinary system consists of
Kidneys
Ureters
Bladder
Functional unit of the kidney; each kidney contains more than a million
Nephrons
3 functions of the nephrons
Filter waste products from the blood
Reabsorb water and nutrients (e.g., glucose and amino acids) from the tubular fluid
Secrete excess substances in the form of urine
In the average person, the nephron filters approximately how much water out of glomerular blood each day and how much of that is excreted in the urine? Therefore, more than what percentage of water is reabsorbed into tubular blood?
Nephron filters approximately 190 L of water out of glomerular blood each day (this enormous amount is many times the total volume of blood in the body); however, only a small proportion of this water (1-2 L) is excreted in the urine. Therefore, more than 99% of water is reabsorbed into tubular blood
Tuft of capillaries with very thin walls and a large surface area where the formation of urine begins
Glomerulus
Reservoir for urine before it leaves the body
Bladder
Triangular area of the posterior bladder, between the openings for the ureters and urethra
Trigone
Where do the ureters enter the bladder and where is the urethral opening?
Through an oblique tunnel that functions as a valve to prevent vesicoureteral reflux during bladder contraction
The openings of the two ureters lie at the posterior corners of the trigone and the urethral opening is situated at the anterior lower corner
Approximately how many mL’s fills the average person’s bladder?
250 mL
Filling of the bladder stimulates autonomic nerve endings in the wall that are perceived as a distended sensation and the desire to void
Micturate
Nervous system injury results in involuntary emptying of the bladder at intervals
Incontinence
A rare congenital anomaly (born with it) in which only one kidney forms, associated with a variety of other malformations
Imaging appearance: IVU = hypertrophic single functioning kidney
Unilateral renal agenesis (solitary kidney)
A rare anomaly in which a small, rudimentary third kidney forms
Functions normally, but is prone to infections that eventually may require its removal
Imaging appearance: IVU = hypoplastic 3rd kidney, may or may not be fused
Supernumerary kidney
Appears as a miniature replica of a normal kidney, with good function
Hypoplastic kidney
An acquired condition that develops when one kidney is forced to perform the function normally carried out by two kidneys
Lone kidney usually a little bigger to make up for the other one
Compensatory hypertrophy
Abnormally positioned kidney that may be found in various locations
Ectopic kidney
Kidney in the true pelvis
Pelvic kidney
Kidney above the diaphragm
Intrathoracic kidney
Both kidneys are malrotated, and fused at the lower poles (joined by a band of normal renal parenchyma [isthmus] or connective tissue)
The most common fusion anomaly
Horseshoe fusion
Rotation of the kidney on the longitudinal or horizontal axis; asymptomatic
Imaging appearance: bizarre appearance of renal parenchyma, calyces, and pelvis
Malrotation
An ectopic kidney lies on the same side as the normal kidney and is very commonly fused
Crossed ectopia
A rare kidney anomaly that produces a single irregular mass that has no resemblance to a renal structure
Complete fusion
Disk, cake, lump, and doughnut kidney
A common anomaly that varies from a simple bifid pelvis to a completely double pelvis, ureter, and ureterovesical orifice.
Complete can be complicated by obstruction or by vesicoureteral reflux with infection
Duplication (duplex kidney)
Cystic dilatation of the distal ureter near its insertion into the bladder
Uretrocele
2 types of uretrocele
Simple (adult)
Ectopic (found almost exclusively in infants and children, commonly associated with ureteral duplication)
Nonsuppurative inflammatory process involving the tufts of capillaries (glomeruli) that filter the blood within the kidney and causes oliguria
An antigen–antibody reaction that most commonly occurs several weeks after an acute upper respiratory or middle ear infection with certain strains of hemolytic streptococci
More frequently, the inflammatory process is caused by a chronic autoimmune disorder
Causes the glomeruli to be extremely permeable, allowing albumin and red blood cells to leak into the urine (resulting in proteinuria or hematuria)
Glomerulonephritis
Smaller-than-normal amount of urine
Oliguria
Suppurative inflammation of the kidney and renal pelvis caused by pyogenic bacteria
It affects the interstitial tissue between the tubules
Patchy distribution
Often affects only one kidney but is asymmetric if both kidneys are involved.
Infection usually originates in the bladder, ascends the ureter to involve the kidneys
More common in women and children
Develops in patients with obstruction of the urinary tract (enlarged prostate gland, kidney stone, congenital defect); instrumentation or catheterization of the ureter is also a contributing factor
Causes stagnation of urine: a breeding ground for infection
Pyelonephritis
Pus-forming
Pyogenic
Painful urination
Dysuria
Pus in the urine
Pyuria
Severe form of acute parenchymal and perirenal infection with gas-forming bacteria that occurs virtually only in diabetic patients and causes an acute necrosis/death of the entire kidney
Imaging appearance: the presence of radiolucent gas shadows within and around the kidney is a pathognomonic
Emphysematous pyelonephritis
6 symptoms of pyelonephritis
High fever
Chills
Sudden back pain that spreads over the abdomen
Dysuria
Pyuria
Bacteria can be cultured from the urine or observed in the urinary sediment
Usually occurs as a secondary infection from lung involvement (hematogenous spread) but can evolve from other sites
Manifests 5 to 10 years after the primary infection
May lead to the development of small granulomas scattered in the cortical portion of the kidneys
Renal tuberculosis
Destructive process involving a varying amount of the medullary papillae and the terminal portion of the renal pyramids
Predisposing factors include diabetes, pyelonephritis, urinary tract infection, urinary tract obstruction, sickle cell disease, and phenacetin abuse
Papillary necrosis
An inflammation of the urinary bladder
Most common nosocomial infection
Most common in women due to a shorter urethra
Symptoms: urinary frequency, urgency, and burning sensation
Cystitis
4 causes of cystitis
Spread of bacteria present in fecal material which reaches the urinary opening and travels up to the bladder (major cause)
Instrumentation or catheterization of the bladder
Retrograde flow from urine bag (bag must be kept below the patient to prevent retrograde flow)
Sexual intercourse
Most commonly form in the kidney
Asymptomatic until they lodge in the ureter and cause partial obstruction, results in extreme pain that radiates from the area of the kidney to the groin
More than 80% of symptomatic renal stones contain enough calcium to be radiopaque and detectable on plain abdomen radiographs
Noncontrast helical CT used most frequently to be demonstrate
Small renal stones (= 3 mm) may pass spontaneously in the urine
Cause of kidney stones varies: often reflect an underlying metabolic abnormality, such as hypercalcemia (resulting from hyperparathyroidism), any cause of increased calcium excretion in the urine, and urinary stasis and infection
Urinary calculi
Calcium can also deposit within the renal parenchyma
Nephrocacinosis
Major causes in adult: urinary calculi, pelvic tumors, urethral strictures, and enlargement of the prostate gland
Normal parts of narrowing that are common sites: ureteropelvic and ureterovesical junctions, bladder neck, and urethral meatus
Noncontrast helical CT scanning detects mass effects, stones, and other causes better than intravenous urography
If the lesion is at or below the level of the bladder (as in prostatic hypertrophy or tumor), bilateral involvement is the rule
Urinary obstruction
Blockage above the level of the bladder causes unilateral dilation of the ureter
Hydroureter
Blockage above the level of the bladder causes unilateral dilation of the ureter and renal pelvicalyceal
Distention of the pelvis and calyces of the kidney
Condition characterized by excess fluid in a kidney due to a backup of urine
Hydronephrosis
Most common unifocal mass of the kidney (simple)
Fluid-filled, usually unilocular (septa sometimes divide the cyst into chambers)
Varies in size
May occur at single or multiple sites in one or both kidneys
Don’t usually show up on plain radiographs without contrast; show up well on ultrasound
Renal cyst
Inherited disorder in which multiple cysts of varying size cause lobulated enlargement of the kidneys and progressive renal impairment
One-third of patients also have liver cysts
Do not interfere with hepatic function
Additive
About 10% have one or more saccular (berry) aneurysms of cerebral arteries; may rupture and produce a fatal subarachnoid hemorrhage
Many are hypertensive
Most tend to be asymptomatic during the first three decades of life
Early diagnosis is made either by chance or by specific search due to family history
Polycystic kidney disease
Most common renal neoplasm
Occurs predominantly in patients older than 40 years
CT and ultrasound
Renal carcinoma originates in the tubular epithelium of the renal cortex
Classic symptom triad: hematuria, flank pain, and palpable abdominal mass
Renal carcinoma
Hypernephroma
4 most common sites of metastasis of renal carcinomas
Lungs
Liver
Bones
Brain
Most common abdominal neoplasm of infancy and childhood
Arises from embryonic renal tissue, may be bilateral
Tends to become very large and appear as a palpable mass
Wilms’ tumor (nephroblastoma)
Most commonly originates in the epithelium
Most common in men over age 50
Fourth most common cancer in men
Predisposing factors: industrial chemicals, cigarette smoking (presumably due to carcinogenic metabolites being excreted in urine)
Carcinoma of the bladder Urothelial carcinoma (previously: transitional cell carcinoma)
Occurs most frequently in children who are severely dehydrated
Magnetic resonance angiography (MRA) can detect an abnormally strong signal from the renal veins, suggesting stasis (no flow) of blood
In adults, is most often a complication of another renal disease: chronic glomerulonephritis, amyloidosis, pyelonephritis, trauma, thrombus extension from inferior vena cava, direct invasion or extrinsic pressure renal tumors
Renal vein thrombosis
Rapid deterioration in kidney function that results in the accumulation of nitrogen-containing wastes in the blood
Causes a characteristic urinelike odor or “fishy” breath
Two types: prerenal (causes: decreased blood flow to the kidneys [hemorrhage, dehydration, surgical shock], cardiac failure, and renal artery obstruction) and postrenal (causes: urine outflow obstruction from both kidneys, prostatic disease, and functional obstruction of the bladder neck)
Other causes: kidney diseases, such as glomerulonephritis, bilateral acute pyelonephritis, and malignant (severe) hypertension, nephrotoxic agents (antibiotics, radiographic contrast material, anesthetic agents, heavy metals, organic solvents), intravascular hemolysis, and large amounts of myoglobin (muscle protein) in the circulation from muscle trauma or ischemia
Acute renal failure
May reflect prerenal, postrenal, or intrinsic kidney disease
Causes include:, bilateral renal artery stenosis, bilateral ureteral obstruction, intrinsic renal disorders, such as chronic glomerulonephritis, pyelonephritis, and familial cystic diseases
Dialysis, kidney transplant, etc.
Chronic renal failure
Excessive water loss in the urine
Polyuria
Presence of blood in urine
Hematuria
Accelerates the heart rate
Epinephrine
Striated muscle that composes the walls of the four chambers of the heart
Myocardium
Smooth delicate membrane that lines the hearts walls that is continuous with the inner surface of the blood vessels
Endocardium
Partition that separates the right and left sides of the heart
Septum
Valves between each atrium and its associated ventricle (one on the right and one of the left side of the heart) which permit blood flow in only one direction
Atrioventricular valves
The atrioventricular valves consist of flaps/cusps of endocardium that are anchored to the papillary muscles of the ventricles by cordlike structures
Chordae tendinae
Valve between the left atrium and left ventricle that has two cusps
Mitral valve
Bicuspid valve
Left atrioventricular
Valve between the right atrium and the right ventricle that has three cusps
Tricuspid valve
Right atrioventricular
Valves that separate the ventricles from the great vessels leaving the heart
Semilunar valves
Valve that lies between the right ventricle and the pulmonary artery
Pulmonary valve
Valve that separates the aorta from the left ventricl
Aortic valve
General circulation of the body
Systemic circulation
Contraction phase of the atria and ventricles
Systole
The heart chambers relax and fill with blood
Diastole
Relaxation phase
Double membranous sac that surrounds the heart
Has a well-lubricated lining that protects against friction and permits the heart to move easily during contraction
Pericardium
What is the function of the cardiovascular system?
To maintain an adequate supply of blood to all the tissues of the body by the rhythmic contractions of the heart
System that controls heart rate
Autonomic nervous system
Most common congenital cardiac lesions
Permit mixing of blood in the systemic and pulmonary circulations.
Lungs become overloaded with blood because blood is preferentially shunted from the high-pressure systemic circulation to the relatively low-pressure pulmonary circulation
Defect size and pressure differences control magnitude of shunt
Always looking at aorta
Imaging: doppler echocardiography (US) and MRI/A
Left-to-right shunts
3 types of left-to-right shunts
Atrial septal defect (most common)
Ventricular septal defect
Patent ductus arteriosus (remnant of fetal circulation)
Most common cause of cyanotic congenital heart disease; without surgical repair, most patients die before reaching puberty
Tetralogy of Fallot
4 (tetra) abnormalities of Tetralogy of Fallot
High ventricular septal defect
Pulmonary stenosis
Overriding of the aortic orifice above the ventricular defect
Right ventricular hypertrophy
Ventricular septal defects and the overriding of the aorta produce shunting of unoxygenated venous blood into the left ventricle and then into the systemic circulation, thus increasing the degree of cyanosis
Right-to-left shunting
The narrowing, or constriction, of the aorta that most commonly occurs just beyond the branching of the blood vessels to the head and arms
Classic sign: normal blood pressure in the arms, but very low blood pressure in the legs
The most frequent cause of hypertension in children
Coarctation of the aorta
Narrowing of the lumen of one or more of the coronary arteries
Most common cause is atherosclerosis
Results in oxygen deprivation of the myocardium and ischemic heart disease
Predisposing factors: hypertension, obesity, smoking, high-cholesterol diet, and lack of exercise
Coronary artery disease
Deposition of fatty material on the inner arterial wall
Atherosclerosis
Inability of the heart to propel blood at a rate and volume sufficient to provide an adequate supply to the tissues.
Causes include: intrinsic cardiac abnormality, hypertension, and any obstructive process that abnormally increases the peripheral resistance to blood flow
Imaging appearance: cardiac enlargement (large heart)
Congestive heart failure (CHF)
Abnormal accumulation of fluid in the extravascular pulmonary tissues
Most common cause is an elevation of the pulmonary venous pressure usually due to left-sided heart failure but may also be caused by pulmonary venous obstruction (mitral valve disease and left atrial tumor) or lymphatic blockade (fibrotic, inflammatory, or metastatic disease involving the mediastinal lymph nodes)
Other causes: uremia, narcotic overdose, exposure to noxious fumes, excessive oxygen, high altitudes, fat embolism, adult respiratory distress syndrome, and various neurologic abnormalities
Imaging appearance: increased pulmonary venous pressure first appears as a redistribution of blood flow from the lower to the upper lung zones (this phenomenon causes prominent enlargement of the superior pulmonary veins) and fluid in the interstitial space causes a loss of the normal sharp definition of pulmonary vascular markings
Pulmonary edema
Leading cause of strokes and CHF
Doesn’t show up on x-rays
Hypertension
High blood pressure
Function of cardiac output and the total peripheral resistance, which reflects the condition of the walls of the blood vessels throughout the body
Blood pressure
The amount of blood pumped per minute by the heart
Cardiac output
What is high blood pressure?
Elevation of the systolic pressure above 140 millimeters of mercury (mm Hg) and of the diastolic pressure above 90 mm Hg
Localized dilatation of an artery that most commonly involves the aorta, especially its abdominal portion
Ultrasound (ultrasonography) is the modality of choice for detection of an abdominal aortic; CTA and MRA
Aneurysm
2 types of aneurysms
Saccular aneurysm
Fusiform aneurysm
Aneurysm that involves only one side of the arterial wall
Saccular aneurysm
Bulging of the entire circumference of the vessel wall
Fusiform aneurysm
4 causes of aneurysms
Atherosclerosis
Syphilis or other infection
Trauma
Congenital defect such as Marfan’s syndrome
Potentially fatal complication of closed chest trauma, such as: rapid deceleration, blast, or compression
Usually the aortic tear occurs distal to the left subclavian artery at the site of the ductus arteriosus
Traumatic aortic rupture
Potentially life-threatening condition in which disruption of the intima (the inner layer) permits blood to enter the wall of the aorta and separate its layers
Creates a true and false lumen in the aorta
The false lumen may form an aneurysm as a result of the high pressure in the systemic vascular system
Most common in patients with arterial hypertension
Other causes: trauma or congenital defects, such as Marfan’s syndrome
Aortic dissection
Characterized by thickening, hardening, and loss of elasticity in the arterial wall
Plaques (fatty deposits) develop in the intima that produces progressive narrowing and often complete occlusion of large and medium-size arteries
One form of arteriosclerosis
Major cause of vascular disease of the extremities
Atherosclerosis
An intravascular clot in arteries or veins
Causes: stasis, endothelium injury or inflammation, or blood changes (changes in clotting mechanisms; increase in RBCs)
Doesn’t show up on plain film
Treatment: anticoagulants, such as heparin and warfarin (Coumadin), are often used to prevent intravascular clotting; however, these medications also interfere with the person’s normal ability to stop bleeding and may lead to severe hemorrhage from relatively minor trauma or interventional treatment
Thrombus
Part or all of a thrombus that becomes detached from the vessel wall and enters the bloodstream in arteries or veins; potentially fatal
Lodges in other vessels, causing ischemia/occlusion
Other types: fat (due to trauma), septic (from infections), air (air bubbles introduced via trauma, surgery, injection)
Doesn’t show up on plain film
Embolism
An autoimmune disease that results from a reaction of the patient’s antibodies against antigens from a previous streptococcal infection
Damages the heart valves; usually the mitral and aortic valves
Damaged valves are either stenotic (open too narrowly) or insufficient (do not close completely)
Rheumatic fever/heart disease
Stenosis of the mitral valve is almost always a complication of rheumatic disease that results from thickening of the valve by fibrous tissue, calcific deposits, or both
Blood flow is obstructed from leaving the left atrium and passing into the left ventricle during diastole which causes increased pressure in the left atrium and enlargement of this chamber
Mitral stenosis
Most often caused by rheumatic heart disease
Other causes: rupture of the chordae tendineae or dysfunction of the papillary muscles
Regurgitation of blood into the left atrium during ventricular systole causes overfilling and dilatation of this chamber which leads to a decrease in ventricular stroke volume and cardiac output
Affects the left atrium and borders of the heart
Mitral insufficiency
Causes: rheumatic heart disease, congenital valvular deformity (especially of a bicuspid valve), or degenerative process of aging (idiopathic calcific stenosis)
The obstruction to left ventricular outflow increases the workload of the left ventricle
Aortic stenosis
Causes: rheumatic heart disease, syphilis, infective endocarditis, dissecting aneurysm, or Marfan’s syndrome
Reflux of blood from the aorta during diastole causes volume overloading of the left ventricle and dilatation of this chamber
Aortic insufficiency
The development of nodules or vegetations on heart valves caused by deposits of bacteria or fungi (they are larger than rheumatic fever vegetations)
Vegetations are filled with bacteria and tend to break apart easily and form septic emboli
Demonstrated on echocardiography; radiography of little use since cardiac silhouette is often unchanged
Infective endocarditis
Primarily involves the lower extremities
Major source of potentially fatal pulmonary embolism
Precipitating factors: trauma, bacterial infection, prolonged bed rest, and oral contraceptives
May be the earliest symptom of an unsuspected malignancy of the pancreas, lung, or gastrointestinal system
Deep venous thrombosis (DVT)
Dilated, elongated, and tortuous vessels that most commonly involve the superficial veins of the leg just under the skin
Varicose veins
Occlusion of a coronary artery deprives an area of myocardium of its blood supply and leads to the death of muscle cells in the area of vascular distribution
Infarction of the heart muscle
Myocardial infarction (MI) Heart attack
Condition in which the heart suddenly can’t pump enough blood to meet the body’s needs
Most often caused by a severe heart attack
Rare, but often fatal if not treated immediately
Cardiogenic shock
A blockage in one of the pulmonary arteries in the lungs In most cases, it is caused by blood clots that travel to the lungs from the legs or, rarely, other parts of the body (deep vein thrombosis)
Pulmonary embolism
A serous membrane that forms the innermost layer of the pericardium and the outer surface of the heart
Epicardium
One of four chambers of the heart located in the bottom left portion of the heart below the left atrium, separated by the mitral valve
The thickest of the heart’s chambers and is responsible for pumping oxygenated blood to tissues all over the bod
Left ventricle
The chamber within the heart that is responsible for pumping oxygen-depleted blood to the lungs
One of the heart’s four chambers located in the lower right portion of the heart below the right atrium and opposite the left ventricle
Right ventricle
Right upper chamber of the heart that receives deoxygenated blood from the body through the vena cava and pumps it into the right ventricle which then sends it to the lungs to be oxygenated
Right atrium
One of the four chambers of the heart located on the left posterior side
Primary role is to act as a holding chamber for blood returning from the lungs and to act as a pump to transport blood to other areas of the heart
Left atrium
Hollow part or cavity in an organ, in particular each of the two main chambers of the heart, left and right
Ventricle
A large vein that receives blood from the head, neck, upper extremities, and thorax and delivers it to the right atrium of the heart
Superior vena cava
A large vein that receives blood from the lower extremities, pelvis and abdomen and delivers it to the right atrium of the heart
Inferior vena cava
