Lecture 16 Flashcards
Body Water Content
50-60% of body weight is water (Female-Male) found in cells, plasma and interstitial fluid
Electrolytes
Dissolved mineral salts that dissociate in solution (anions/cations)
What is osmoregulation controlled by?
Osmoregulation is controlled by water intake and excretion (sweat, urine) ie – water loss increases sodium concentration.
What is volume regulation controlled by?
Volume regulation is primarily controlled by sodium retention and excretion
Disturbances of H2O balance
Dehydration (more common) through inadequate intake and excess H2O loss (diarrhea or vomiting) or Overhydration (less common) through the excessive fluid intake when renal function is impaired
Hypovolemia
A decrease in plasma volume and loss of blood pressure
Regulation of Plasma pH
Must be maintained between 7.37 and 7.42; regulated by kidneys and respiratory system
What roles does the kidney play in regulating blood pH?
- Kidneys reabsorb bicarbonate and manufacture bicarbonate
- Acidic metabolic products are excreted by the kidney.
Acidosis
Blood pH shifts to acidic side due to an excess of H2CO3 (carbonic acid) or from a reduced amount of bicarbonate
Alkalosis
Blood pH shifts to the basic side due to a decrease of H2CO3 (carbonic acid) or from an increased amount of bicarbonate
Metabolic disturbance
Disturbance lies in bicarbonate member of the buffer pair
Respiratory disturbance
Disturbance lies in carbonic acid members of the buffer pair
Metabolic acidosis and compensatory mechanisms
Increased endogenous acid generated
Compensation: By hyperventilation to lower PCO2 and increased bicarbonate production in kidneys
Respiratory acidosis and compensatory mechanisms
Increased H2CO3 concentration - Inefficient exhalation of CO2 by lungs
Compensation: Increased bicarbonate production in kidneys
Metabolic alkalosis and compensatory mechanisms
Increased plasma bicarbonate concentration from loss of gastric juice, chloride depletion, excess corticosteroids, excess antacids
Compensation: Inefficient, requires simultaneous correction of potassium deficiency
Respiratory alkalosis and compensatory mechanisms
Reduced H2CO3 concentration due to hyperventilation
Compensation: Excretion of bicarbonate by kidneys
Respiratory Control of pH (increase and decrease of respiration)
Increased respiration lowers carbon dioxide concentration making blood more alkaline and decreased respiration causes elevation of alveolar PCO2, raising plasma carbon dioxide
Kidneys
Paired, bean-shaped excretory organs below the diaphragm adjacent to the vertebral column
3 basic functions of the kidney
Excrete waste products of food metabolism, Regulate mineral, electrolyte, acids and H2O balance, Produce erythropoietin, thrombopoietin and renin (specialized kidney cells)
Urea
End product of protein metabolism
Uric Acid
Nucleic acid metabolism
Erythropoietin
Regulates red blood cell production in marrow
Renin
Helps regulate blood pressure
Ureter
Conveys urine into bladder by peristalsis
Renal pelvis
Expanded upper portion of ureter
Major calyces
Subdivisions of renal pelvis
Minor calyces
Subdivisions of major calyces into which renal papillae discharge
Bladder
Stores urine and discharge urine into the urethra during voiding
Urethra
Conveys urine from the bladder for excretion
Nephrons
the basic structural and functional unit of the kidney using filtration, absorption and reabsorption, secretion and excretion, about 1-1.5 million nephrons in each kidney
The Glomerulus
Tuft of capillaries supplied by an afferent glomerular arteriole that recombines into an efferent glomerular arteriole with three layers of the glomerular filter
Mesangial cells
Contractile phagocytic cells that hold the capillary tuft together; regulate caliber of capillaries affecting filtration rate
Glomerular Filtration control Factors
Factors that control GFR are porosity and length of the glomerular capillary, differences in fluid pressure and oncotic pressure (inside/outside capillary) by the kidney through changes in resistance in blood flow
What happens if there is filtration failure
Filtration failure will result in buildup of metabolic toxins and nitrogenous wastes (urea) in the blood (azotemia) which can lead to multi organ failure and death
Renal tubule (proximal and distal end)
Reabsorbs most of the filtrate; secretes unwanted components into the tubular fluid; regulates H2O balance
Proximal end: Bowman capsule
Distal end: Empties into collecting tubules
Control of Plasma Osmolality
Plasma osmolality is mainly controlled by sodium concentration and depends on water uptake and loss (diuresis [urination])
Hyponatremia
Results in cell swelling
Hypernatremia
Cell shrinkage (osmosis)
Diabetes insipidus
Cause by lack of secretion of ADH or failure of kidney response to ADH – resulting in large amounts of urine production (20L/day) and dehydration
Renin release
Released in response to decreased blood volume, low blood pressure– converts angiotensinogen to Angiotensin I
How is Angiotensin I → angiotensin II
Angiotensin-converting enzyme (ACE) as blood flows through the lungs
Hypoperfusion
Low blood pressure or volume –is prolonged causes renal injury
Angiotensin II
Powerful vasoconstrictor (Raises blood pressure) and stimulates aldosterone secretion from the adrenal cortex (reabsorption of NaCl and H2O by kidneys)
Diuretics, types of diuretics, and treatment
Increase water and sodium excretion to reduce blood volume (reduce sodium/water reabsorption)
3 main types:
Loop diuretics (furosemide) – block sodium reabsorption in ascending loop of Henle (major site of sodium reabsorption), Thaizide diuretics (hydrocholorthiazide), and Potassium sparing diuretics (spirolactone)
Treatment: hypertension, edema, CHF
Diagnostic Evaluation of Kidney and Urinary Tract Disease
Urinalysis (pH, conc, glucose, protein, bile, blood, casts), Urine culture - bacteria, Blood chemistry tests, Kidney function tests, BUN (blood urea nitrogen test), Glomerular filtration rate (GFR), Creatinine clearance test, X-ray studies (with/without contrast), Ultrasound examination, Cystoscopy, Renal biopsy/histology, and CT
Normal development of the urinary system
Kidneys arise from mesoderm, develop in pelvis, ascend to final position, bladder is derived from lower end of intestinal tract, ureteric buds develop excretory ducts
Renal agenesis
Failure of one or both kidneys to develop (bilateral - rare, unilateral - common)
Duplications of urinary tract
Complete duplication (formation of extra ureter and renal pelvis) and incomplete duplication (Only upper part of excretory system is duplicated)
Malposition
One or both kidneys, associated with fusion of kidneys; horseshoe kidney; the fusion of upper pole – often of little clinical significance, may have some abnormalities in drainage of urine
Renal Failure
acute (develops rapidly and tends to resolve) or chronic (develops slowly with permanent damage); is associated with retention of urea in the blood (uremia) and metabolic acidosis (inability to remove waste products)
What does pre-renal cause?
Hypertension, atherosclerosis and high sugar levels from diabetes
What does post-renal cause?
Often obstructive – bladder stones, prostatic diseases, cancer
What causes Acute kidney injury?
Trauma/ Surgery complications (decreased renal blood flow), low BP (shock), Urinary tract blockage – stones, cancer, Medications - NSAIDS, Diseases that increase load on kidneys (toxins /muscle deterioration/hemolytic diseases)
Treatment: Treat underlying cause – if done soon enough, should prevent permanent damage to kidney – dialysis may be required until cause is treated
Chronic kidney Injury (CKI)
Renal function remains regular until the number of functioning nephrons declines to 30% of normal.
Hypertensive Nephrosclerosis
Complication of severe, uncontrolled hypertension, increases glomerular pressure
Diabetic Nephropathy
Complication of long-standing diabetes (hyperglycemia) causing progressive impairment of renal function and protein is lost in the urine. May lead to ESRD. Once initiated, can’t be reversed but progress can be slowed dependent on glycemic control (along with Hypertension if present)
Uremia
Progressive loss of renal function due to retention of excessive by-products of protein metabolism (urea) in the blood (uremia);Fluid, electrolyte, acid–base regulation failure (metabolic acidosis and anemia due to lack of erythropoietin) which causes waste accumulation in the blood
Clinical manifestations and treatment in Uremia
Weakness, loss of appetite, nausea, vomiting
Anemia (failure of Epo production – endocrine function), Toxic manifestations from retained waste products (weakness, lethargy, neuropathy (delirium), cardiovascular disease, Retention of salt and water causes edema, Blood volume increased – Hypertension, Coma, convulsions, and death
Treatment: Hemodialysis, Peritoneal Dialysis, and
Transplantation
Dialysis and its types
Substitutes for the functions of the kidneys by removing waste products from patient’s blood; Can be used indefinitely or during period while waiting for kidney transplant
Extracorporeal dialysis (more common): artificial kidney
Peritoneal dialysis (less common) - own peritoneum is used as the dialyzing membrane
Renal Transplantation
When kidneys fail. Best if from a close relative donor (living donor -sibling match) can also be obtained from unrelated –matched deceased donor (HLA matches), More than 90% of transplanted kidneys last for 5 years with good HLA match, 10y survival rate is 50%
Glomerulonephritis
Inflammation of the glomeruli caused by immune reaction within glomerulus - Autoimmunity following a beta-streptococcal infection; Could turn into ESRD without immunosuppressive therapy. Decreases urine output - waste accumulation in blood.
Diseases: Occurs in Lupus, immune complexes trapped in glomeruli and occurs in IgA nephropathy
Poststreptococcal Glomerulonephritis
Occurs after infection resolved (strep throat) in affected individuals, antistreptococcal antibodies form immune complexes with strep antigens
Anti GBM glomerulonephritis
Autoantibodies against basement membrane –progresses rapidly
ANCA (anti neutrophil cytoplasmic antibody) glomerulonephritis
Characterized by destruction/inflammation of small blood vessels. They reach with the cytoplasmic components of neturophils
Renal Cyst types
Solitary cysts common; not associated with impairment of renal function
Multiple cysts from congenital polycystic kidney disease; cysts will enlarge and destroy renal tissue which will cause early onset of kidney failure. Confirmed by ultrasound/CT
Renal Tumor Types
Cortical tumors: Arise from epithelium of renal tubules
Transitional cell tumor: Arise from transitional epithelium lining urinary tract
Nephroblastoma Arise from remnant embryonic tissue: Uncommon; highly malignant, metastasizes widely; affects infants and children
Diagnosis and treatment of renal tumors
Urinalysis, culture, clearance tests, Blood chemistry tests, X-ray, ultrasound, cystoscopy, biopsy
Treatment: Nephrectomy, radiotherapy, chemotherapy
Nephrotic Syndrome
Glomerular renal disease associated with Marked loss of protein in the urine (nephrosis) that is caused by glomerular disease. The outcomes are the decline in protein levels in blood, edema, Ascites (fluid in abdominal cavity), and Hydrothorax (fluid in pleural cavity)
Acute Renal Tubular Injury pathogenesis and clinical manifestations
Impaired renal blood flow, Tubular necrosis caused by infection, toxic drugs or chemicals, Any condition associated with shock and marked drop in BP – decreased blood supply and damage to tubules
Clinical manifestation: Acute renal failure: Oliguria, anuria
Urinary Tract (UTI)
Very common; may be acute or chronic, Most infections are caused by gram-negative intestinal bacteria that contaminate perianal and genital areas and ascend urethra
How to prevent a UTI
Free urine flow
Large urine volume
Complete bladder emptying
Acid urine: Most bacteria grow poorly in an acidic environment
Cystitis
Affects only the bladder More common in women than men; urethra in female is shorter; in young, sexually active women - sexual intercourse promotes transfer of bacteria from urethra to bladder
(Pain during urination, desire to pee frequently, bacteria and leukocytes in urine, can spread upwards into renal pelvis and kidneys)
Pyelonephritis + symptoms
Ascending infection from the bladder (ascending pyelonephritis) and Carried to the kidneys from the bloodstream (hematogenous pyelonephritis); frequently associated with cystitis
Symptoms: localized pain and tenderness over affected kidney
Vesicoureteral Reflux (VUR)
Failure of valve allows bladder urine to reflux into ureter and into kidneys in severe cases – valve defect/ neurogenic/ urethra blockage causing UTIs, bladder problems, kidney infection and scarring in severe cases
Urinary Calculi
Stones may form anywhere in the kidney/urinary tract. If they remain in the urinary tract they can grow larger
Urinary Calculi predisposing factors
Low fluid intake, High concentration of salts in urine saturates urine, Urinary tract infections and obstructions
Staghorn calculus and treatment
Urinary stones that increase in size to form large branching structures that adapt to the contour of the pelvis and calyces
Treatment
Cystoscopy: remove stones lodged in distal ureter
Xray/shock wave lithotripsy: Stones lodged in proximal ureter are broken into fragments that are readily excreted
Urinary Obstruction, complications, diagnosis, and treatment
Blockage of urine outflow leads to progressive dilatation of urinary tract proximal to obstruction, eventually causes compression, destruction of kidney parenchyma and atrophy; can be bilateral or unilateral
Complications: stone formation, infections, Kidney damage/failure
Diagnosis and treatment: Pyelogram (X-ray with IV contrast – collects in urine, CT scan)
Kidney cancer
Typically form in the tubules (renal cell carcinoma) most are found before they can spread, easily treated when caught early causes hematuria, fatigue, weight loss, and anemia
Bladder/ureteral cancer types
Urothelial carcinoma (most common) - cells that line the bladder/ureters and squamous and adenocarcinoma (rare) causing hematuria, painful/frequent urination, and lower back pain on 1 side
Urethral cancer + symptoms
Rare – 1% of all urogenital cancers
Symptoms: Hematuria, painful urination, unable to empty bladder – frequent urge to urinate
