OPTA 222 (Renal System patho and disorders)
Stucture and Location
Two bean shaped organs that lie outside the peritoneal cavity, in the back of the upper abdomen. One on each side of vertebral column between the 12th thoracic to 2nd lumbar vertebrae.
Each kidney is 10-12cm long and 5-6cm wide.
Urine Formation
- Filtration of plasma through glomerular capillaries
- Fluid movement is determined by: Capillary filtration pressure, Colloidal osmotic pressure, Capillary permeability
- This plasma is similar to the rest of the body but does not contain larger molecules like proteins
- Once the filtrate moves into the tubular segments of the nephron reabsorption and secretion between the tubule and the peritubular capillary occur: Active transport is the mechanism of movement for Na, K, Cl and Ca; Passive transport is used for water and urea
How the kidney concentrates urine reading
- Most of nutritionally important substances are reabsorbed: Na+, K+, Cl-, bicarbonate, glucose, amino acids, lactate, water soluble vitamins
- In adults, kidneys are perfused with 20%-25% of the cardiac output.: This ensures sufficient removal of waste products from the blood
Glomerulus
- where blood filtrates
- high pressure capillary system
Bowmans Capsule
doubled wall capsule of capillaries
Bowmans Space
is a fluid filled space in the Bowman's capsale
Filtrate
Portion of blood that filtured into the capsule space
Renal corpuscle
The mass capillaries and surrounding epithelial capsule
Proximal convoluted tubule
y
Loop of henle
recovers of water and sodium chloride from urine
Distale convoluted tubule
y
Collecting tubule
join with several tubule to collect filtrate
Diluting segment
Reabsorbs salt from urine
Late distale tubule
fuses with the collecting tubule
Cortical colllecting tubule
raise the fractional solute contribution and absolute concentration of area in fluid that it delivers to outer medullary collection
Inner collecting tubule
recieves filtrate from multiple initial collecting tubules and decreasesinto renal medulla
Autoregulatory Mechanisms
- Normally autoregulation ensures blood flow is maintained to kidneys in consistency with the metabolic needs of the tissues
- Also allows for regulation of solute and water excretion
- One mechanism is that when there in an increase in blood pressure, the vasculature relaxes
Elimination functions of kidney
- Regulation of sodium and potassium elimination
- Regulation of pH
- Uric acid elimination: High uric acid can cause kidney stones, Associated with gout
- Urea elimination: End product of protein metabolism
- Drug elimination
Endocrine functions of kidney
- Kidneys produce chemical mediators that travel through the blood to distant sites where they exert their action mechanism.
- Kidneys participate in control of blood pressure (through the renin-angiotensin-aldosterone system)
- Participate in regulating red blood cell production
- And calcium metabolism
Diuretics
- Increase urine volume
- They often work by blocking Na+ reabsorption so usually result in the loss of Na+ and water
- Can be prescribed when have fluid build up in body
Disorders
Kidney function assists in regulation of the following:
-Fluid and electrolyte balance
-acid/base balance
As such, disorders related to both can be impacted by kidney function
Disorders of fluid and electrolyte imbalance
- Compartmental distribution of bodily fluids: Extracellular and intracellular fluid volume, Note: ECF is more easily lost from the body, Infants normally have higher ECF rate so are more prone to dehydration
- Capillary -interstitial fluid exchange: Edema
- Body water balance: Amount of total body composition made up of water, Normal total body water changes for age/gender
-Sodium balance
-Disorders of thirst and antidiuretic hormone: Hypodipsia, Polydipsia
Disorders of water and sodium balance
- Hyponatremia: Low sodium, Elderly more susceptible
- Hypernatremia:High sodium
Disorders of potassium balance
- Hyperkalemia
- Hypokalemia
Disorders of calcium balance
- Hypercalcemia
- Hypocalcemia
Disorders of phosphorous balance
- Hypophosphatemia
- Hyperphosphatemia
Disorders of phosphorous balance
- Hypophosphatemia
- Hyperphosphatemia
Metabolic acidosis
- Body compensates for decrease in pH by increasing the respiratory rate in an effort to decrease PCO2 (pressure of carbon dioxide) and H2CO3 (carbonic acid)
- Weakness, fatigue, general malaise, dull headache, abdominal pain, vomiting, nausea
- When pH falls to 7.1 to 7.2, cardiac contractility decreases, can get fatal ventricular arrythmia
Metabolic alkalosis
- Excess HCO3 causing increase in pH
- Caused by increased consumption of base, loss of acids from stomach, hypokalemia and hypochloremia
- Significant morbidity can occur
Respiratory acidosis
- Occurs in conditions that cause alveolar ventilation and an increase in PCO2 (hypercapnea)
- Causes include lung disease
- Symptoms:headache, blurred vision, irritability, psychological disturbances
- Can lead to respiratory depression, coma etc.
Respiratory alkalosis
- Hypocapnea not enough o2
- Hyperventilation or respiratory rate increase
- Lightheadedness, numbness, tingling in fingers and toes, sweating, palpitations, convulsions