11.2.3 Excretory system and Kidneys

• What is the key term for when nutrients are taken up by cells?

  Assimilation
• What happens to excess amino acids in the body?

  They are broken down to produce urea
• Where is urea produced in the body?

  Liver
• How is urea excreted from the body?

  It is filtered by the blood in the kidneys

  
• What is excretion?

  Removal of waste products from the body
• What are examples of substances excreted from the body?

  Carbon dioxide and urea

  
• What are the roles of the liver?

  1. Deamination (making urea from excess amino acids)
  2. Production of bile (emulsifies large fat globules)
  3. Storage of glycogen (taking up glucose when insulin is released)
  4. Detoxification of alcohol/drugs

  
• What is the basic role of the kidney in urine formation?

  Regulates water, salt content, and removes urea

  
• How does blood reach the kidney?

  Through the renal artery
• What is formed from the filtered excess water, salts, and urea?

  Urine

  
• How is urine transported from the kidneys?

  Along tubes called ureters
• What does the bladder do?

  Stores urine until expulsion
• How does purified blood return to circulation?

  Through the renal vein
• What are nephrons?

  Structures in the kidney that filter blood

  
• Where do nephrons start in the kidney?

  Cortex
• What processes do nephrons use to regulate substances?

  Filtration and reabsorption

  
• What is the glomerulus involved in?

  Ultrafiltration
• Why is there high pressure in the glomerulus?

  The incoming arteriole is wider than the outgoing
• What small molecules are forced out of the capillaries in the glomerulus?

  Glucose, urea, water, and salts

  
• What remains in the capillaries during ultrafiltration?

  Large molecules like plasma proteins
• What does the filtrate in the Bowman’s capsule contain?

  Glucose, water, urea, and salts
• What happens in the proximal convoluted tubule?

  Selective reabsorption of water and glucose

  
• What percentage of glucose is reabsorbed in the proximal convoluted tubule?

  100%

  
• What features of proximal convoluted tubule cells aid in reabsorption?

  Many mitochondria and microvilli

  
• What is the function of the loop of Henle?

  Water reabsorption
• How does the loop of Henle differ in animals in dry environments?

  It is longer
• What does the collecting duct allow?

  Reabsorption of water back into blood

  
• What hormone is released when dehydrated?

  ADH
• What effect does ADH have on the collecting duct?

  Increases permeability for water reabsorption

  
• What happens to urine volume when dehydrated?

  It is low in volume and concentrated

  
• What does dark yellow urine indicate?

  You are dehydrated

  
• What does light yellow urine indicate?

  You are well hydrated

  
• What factors affect urine composition?

  • Increased volume: lots of water intake
  • Decreased volume: dehydration
  • Increased concentration: dehydration
  • Decreased concentration: well hydrated
• Deamination


  The process by which the liver converts amino acids into urea, carbon dioxide, and energy.
• Kidney


  The organ responsible for removing urea from the bloodstream and excreting it out of the body through urination.
• Liver


  The organ responsible for producing urea through deamination, converting amino acids into urea, carbon dioxide, and energy.