Chapter 8 - Kidney
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What are the most toxic wastes removed by the Kidneys?
Nitrogenous wastes, urea, uric acid and creatine.
Function of a Kidney.
Kidneys are the principal excretory organs. They are responsible for maintaining the constant concentration of materials in the body fluids.
How is Urea produced?
In the liver from the breakdown of amino acids, which come from protein metabolism.
What is a Nephron?
The nephron is the functional unit of the kidney as it is where the urine is formed.
Describe the Structure of the Nephron.
• Consists of a renal corpuscle and a renal tubule. • Begins with an expanded end called the Glomerular Capsule which is surrounded by a know or arterial capillaries called the glomerulus. • Followed by a Proximal Convoluted Tubule -> Loop of Henle -> Distal convoluted tubule -> Collecting Duct -> Renal Pelvis.
How many Nephrons are there in a Kidney?
1 million
How does blood enter the Kidney?
Through the Renal Arteries. Renal Arteries -> Afferent Arteriole -> Glomerulus -> Efferent Arteriole.
What are known as the Peritubular Capillaries?
The capillaries surrounding the proximal and distal convoluted tubules of the nephron.
List the three major process of Urine formation.
• Glomerular Filtration • Selective Reabsorption • Secretion by the tubules
Explain Glomerular Filtration.
• Takes place in the Renal Corpuscle. • Due to the high pressure of blood in the glomerulus, fluid (water and dissolved blood components) is vigorously forced through the differentially permeable cell membranes and into the capsule. =Filtrate (H2O, Na+, aa, C6H12O6, urea, uric acid, creatine, hormones, toxins and various ions). • The Afferent has a wider diameter than the Efferent. = Increase resistance In blood flow.
Explain the process of Reabsorption.
• Selective Reabsorption is carried out by the cells that line the Renal Tubule. • The large surface area for effective Reabsorption of materials is achieved by the long length of the kidney tubule. (2 convolutions, long LOH, #nephrons) • Water can be reabsorbed by the body’s requirements. This is an active process under hormonal control; Facultative Reabsorption.
Explain Tubular Secretion.
• Adds materials to the filtrate from the blood. (K+, H+, creatine and drugs-penicillin) • Active/Passive process • Removes certain unwanted materials = Controls pH of the blood. • To raise the pH of the blood, the tubules secrete hydrogen and ammonium ions.
Role in Renal corpuscle.
• Filtration of blood from capillaries of glomerulus. * Formation of Filtrate in the Glomerular Capsule.
Role in Proximal convoluted tubule and the Loop of Henle.
• Reabsorption of Na+, K+, Cl- and CHO3-, Glucose * Passive Reabsorption of water by diffusion.
Role in Distal Convoluted Tubule.
• Reabsorption of Na+ * Active Reabsorption of water depending on the body’s needs.
Role in Collecting Duct
Active Reabsorption of water depending on the body’s needs.