BIOL 1140 Chapter Notes - Chapter 17: Reabsorption, Positive Feedback, Collecting Duct System
5 Jun 2018
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Human Biology Review Unit 17
Overview: Urinary system—function is to excrete nitrogenous wastes, excess solutes, and water from
body; plays a major role in maintaining homeostasis in the body
• Urinary system structure
• Urea
o Chemical that stores high concentrations of nitrogen
o Less toxic than ammonia, must be excreted from body
• Kidneys
o Primary organ of urinary system
o Filter waste product from blood
• Ureters
o Carry urine from kidneys to bladder
• Bladder
o Sac like muscular organ that collects urine
• Urethra
o Tube that carries urine from bladder to exterior organ
• Nephron
o Functional units of the kidney
o Adjust the composition of blood and produce urine
o Blood never physically enters the nephron
Path of blood
o Renal artery
o Supplies unfiltered blood to the kidneys
o Artery branches out into multiple arterioles
o Arterioles branch and come in close contact with nephron
o Arterioles
o Smaller arteries
o Glomerulus
o A tuft of capillaries where blood is filtered
o Peritubular capillaries
o Surround each nephron
o Further filtration occurs here
o Venule
o Filtered blood is collected here
Urine formation
1. Filtration
o H2O and plasma get filtered out of blood
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Document Summary
The nitrogenous waste ammonia is usually converted to a less toxic substance known as: amino acids, urea, fatty acids, sodium chloride crystals, uric acid. When urine leaves the kidneys, it enters the: urethra, liver, ureter, urinary bladder, nephron, kidney, capillary network, filtrate, nutrient, waste producte. Excretes nitrogenous wastes, excess solutes, and water from body. Depict and describe the path of blood through a kidney, be sure to name the structures that blood passes through. Describe the process of urine formation and note where filtration, reabsorption, secretion, and excretion occur. Filtration: h2o and plasma get filtered out of blood. Reabsorption: useful materials reenter the blood (water and nacl, occurs in proximal tube and loop of henle. Secretion: toxic substances are secreted back into the nephron, occurs in the distal tube of the nephron. Excretion: removal of waste from body, occurs in the collecting duct of nephron. Proximal tube & loop of henle are where nutrients and waters are absorbed.
