Excretion and Osmoregulation

• What is excretion?

  Removal of metabolic waste products
• What are the excretory organs in the human body?

  • Skin: Removes salt, water, and urea
  • Lungs: Remove carbon dioxide and water
  • Liver: Breaks down toxins and waste
  • Kidneys: Filter blood and produce urine
• What is the role of the skin in excretion?

  Removes salt, water, and waste products
• How do the lungs contribute to excretion?

  They remove carbon dioxide and water
• How does urine travel from the kidneys?

  Through the ureters to the bladder
• What is the role of the sphincter muscle in the bladder?

  Controls the release of urine
• What is the function of the urethra?

  Passes urine from the bladder
• What is the process of osmoregulation?

  • Balance of water and salt in the body
  • Hypothalamus detects blood concentration
  • Pituitary gland secretes antidiuretic hormone (ADH)
  • ADH affects kidney tubules' permeability
• What happens if blood is too concentrated?

  ADH secretion increases, reabsorbing more water
• What is the result of increased ADH secretion?

  Small amounts of dark yellow urine
• What occurs if blood is too dilute?

  ADH secretion decreases, reabsorbing less water
• What is the result of decreased ADH secretion?

  Large amounts of pale yellow urine
• How do plants excrete oxygen and water vapor?

  They diffuse out through the leaf stomata
• What are the waste products excreted by plants?

  • Oxygen: Released during photosynthesis
  • CO₂: Released during respiration
  • Water: Released through transpiration
  • Organic waste: Tannins, latex, calcium oxalate
• What method do some plants use to excrete waste?

  Shedding their bark
• What happens to organic waste in plants?

  Some waste is in leaves that fall off
• What are the differences in excretion between humans and plants?

  Humans:

  • Excrete through skin, lungs, liver, kidneys
  • Produce urine as waste

  
  

  Plants:

  • Excrete through diffusion and shedding
  • Release oxygen, CO₂, and water vapor
• What does the afferent arteriole do?

  Brings blood towards the nephron
• Why is the afferent arteriole larger than the efferent arteriole?

  To create pressure for filtration
• What is forced out of the glomerulus into the Bowman’s capsule?

  Small particles like water and glucose
• Which substances are included in the filtrate that enters Bowman’s capsule?

  Water, salt, urea, and glucose
• Where is all of the glucose reabsorbed in the nephron?

  Proximal convoluted tubule
• What happens to water and salt in the loop of Henlé?

  Some water and salt are reabsorbed
• What occurs in the distal convoluted tubule?

  Some water and salt are absorbed
• What substances pass into the collecting duct?

  Excess salt, excess water, and urea
• What is the final product of the substances passing through the nephron?

  Urine