Introduction to Renal System Flashcards
gross function of Kidneys (the renal system)
Produce urine (filtration, reabsorption, secretion)
gross function of Ureter
Ureter (one per kidney) carry urine away from the kidneys and to the urinary bladder
gross function of Urinary bladder
The urinary bladder is a muscular, elastic sac which stores urine arriving via each ureter
gross function of Urethra
A duct which allows urine to leave the bladder (and body itself) via the process of urination.
Kidney – anatomy
Two kidneys
• Located either side of vertebral column
- Average kidney measures 11 x 7 x 3 cm
- Left kidney often slightly larger than the right
• Right kidney usually slightly lower than the left
– Thought to be due to positioning of the liver
Kidneys surrounded in layer of fat for support
Organs of urinary system
Kidney, ureter, bladder, urethra
Hilum
Indentation – entry of renal artery and nerves, exit of renal vein and ureter
Renal pelvis
The enlarged portion of the ureter as it leaves the kidney. Also the point of mergence for the major calyces
Cortex
Outer layer of kidney
Medulla
Inner part of kidney
Nephron
– Structural and functional unit of kidney
– Site of urine production
– 1 million/kidney
Veins
carry deoxygenated blood towards the heart
Arteries
carry oxygenated blood away from the heart
Typical direction of blood flow
Arteries → Arterioles → Capillaries → Venules → Veins
Renal vein
carries blood away from the kidney
Renal artery
carries blood towards the kidney
Blood flow through kidney
approximately 1200 mL/min
Kidney – primary functions
Main organs of excretion
- Filter blood to make urine
- Remove excess water, ions, urea, toxic substances
• Involved in blood homeostasis – Osmotic pressure – Volume – Pressure – Ion concentration – pH
Produce the hormone erythropoietin (kidney)
Also known as haematopoietic or haemopoietin
Hormone released into bloodstream in response to low blood-oxygen levels (hypoxia)
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Carried to the bone marrow
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Stimulates stem cells (called pluripotent stem cells)
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Cells undergo maturation – become red blood cells (erythrocytes)
Produce the hormone renin (kidney)
Renin – Enzyme secreted by kidneys
– Increases blood pressure
– Regulate extracellular fluid (plasma, lymph)
– Allows for arterial vasoconstriction
• Narrowing of arteries → increase in pressure
Kidneys - Urine
– Filter blood to make urine
– Remove excess water, ions, urea, toxic substances
Nephron - Urine
– Structural and functional unit of kidney
– Site of urine production and electrolyte balancing
Electrolyte balancing - Urine
Key to blood homeostasis
Urine – facts and composition
- Main role of kidneys – filter blood to produce urine
- Adult bladder holds 400-600 mL of urine
• Urine is ~95% water, ~5% dissolved substances
• Most important of the 5% being:
– Toxins
• Toxic substances produced by harmful bacteria during an infection
– Nitrogenous waste
• Urea, uric acid, ammonia
Hormones - Urine
Excess hormone levels
Electrolytes - Urine
Diet dependant but in general: Na+, Cl- , K+ phosphate, bicarbonate
Pigments - Urine
Mostly from breakdown products of old red blood cells, these products are often yellow in colour
Abnormal elements - Urine
Stones (calculi), mucus, blood, sugar (glucose)