excretion

• excretion


  the removal of metabolic waste products from the body
• example of metabolic waste


  CO2 and nitrogenous waste such as urea
• Why is excretion important?

  so metabolic waste doesn't accumulate as they're toxic

  > interfere with cell processes by altering the pH

  > preventing normal metabolism

  > or acting as inhibitors and reduce enzyme activity
• function of liver


  - breaks down amino acid into urea (involves deamination)

  - detoxifies the blood

  - stores glycogen

  -makes bile
• Deamination


  the removal of an amino group from an amino acid
• why is it important that blood is detoxifies

  so alcohol, drugs and hormones can be broken down and excreted in urine
• how does the liver store glycogen

  it converts excess glucose into glycogen
• Why is bile important?

  for lipid digestion by emulsification of fats
• Ornithine cycle


  A series of biochemical reactions that convert ammonia to urea
• Explain the ornithine cycle

  - amino acids are deaminated

  - organic acids are respired or stored as glycogen

  - ammonia is toxic so is combined with carbon dioxide and converted to urea

  - urea is released into the bloodstream

  - filtered by the kidney and excreted by the body
• Vessels of the liver

  - Hepatic artery

  - hepatic vein

  - bile duct

  - hepatic portal vein
• hepatic artery


  delivers oxygenated blood to the liver
• hepatic vein


  takes deoxygenated blood away from the liver.
• hepatic portal vein


  connects the liver to the intestine

  > allows harmful substances that have been removed by the liver to be immediately be broken down
• bile duct


  A tube that carries bile from the liver to the gallbladder
• What is the liver made up of?

  liver lobules
• what are liver lobules made up of

  hepatocytes (liver cells) that radiate out from the central vein
• the central vein


  drains blood from sinusoids and out of liver
• what capillary connects the central vein, hepatic artery and hepatic portal vein

  sinusoids
• Canaliculi


  tube that connects the bile duct and central vein
• Kupffer cells

  macrophages in the liver

  - breaks down old red blood cells

  - removes bacteria from the bloodstream
• function of the kidney

  To filter wastes from the blood stream that can be removed in Urine
• renal medulla (of kidney)


  inner region of the kidney
• renal cortex


  outer region of the kidney
• renal artery


  blood vessel that carries blood through the kidney while being filtered
• renal vein


  blood vessel that carries filtered blood away from the kidney and toward the heart
• nephron


  functional unit of the kidney
• what does the kidney remove

  excess water, excess ions and urea from our blood as urine
• the 2 processes involved in the removal of substances by the kidney

  ultrafiltration and reabsorption
• Bowman's capsule


  cup-shaped strucutre of the nephron of a kidney which encloses the glomerulus and which filtration takes place
• efferent arteriole


  carries blood away from the glomerulus
• afferent arteriole


  carries blood to the glomerulus
• Why is the efferent arteriole smaller in diameter than the afferent arteriole?

  So, the blood in the glomerulus is under high pressure.
• Ultrafiltration


  The process where small molecules are forced from the blood out of the capillaries of the glomerulus, under high pressure, into the Bowman's capsule.
• what molecules in the bloodstream are pushed into the bowman's capsule

  glucose, urea, water and salts
• what molecules in the bloodstream can't enter the bowman's capsule and remain in the capillaries

  blood cells and proteins
• glomerular filtrate


  the fluid and dissolved materials that filter out of the blood and enter the nephron through the glomerular capsule
• what are the three layers that molecules pass through between the capillary and kidney

  - capillary endothelium

  - basement membrane

  - epithelium of the Bowman's capsule
• capillary endothelium


  Known as simple squamous endothelium and forms the wall of the capillary.
• basement membrane


  Layer between epithelium and underlying connective tissue