Excretion

    Cards (35)

    • What are some examples of waste products in plants
      • Oxygen
      • Carbon dioxide
      • Water
      • Other unwanted chemical substances
    • During the day (when there is sufficient light) -
      • Rate of photosynthesis is higher than rate of respiration
      • More oxygen is produced than used in respiration
      • Less carbon dioxide is produced than used in photosynthesis
      • NET EFFECT - Oxygen is in excess and is a waste product
    • During the night (when there is insufficient light) -
      • There is no photosynthesis, only respiration
      • Oxygen is used in respiration and carbon dioxide is produced
      • No photosynthesis means no carbon dioxide being used
      • NET EFFECT - Carbon dioxide is in excess and is a waste product
    • Where does the gas in excess come out from
      They diffuse out of the plant via the leaf organ and the gases then exit through the stomata
    • Where are chemical waste materials stored in a plant
      In the dying tissues of a plant
    • What are some examples of metabolic waste in humans
      • Carbon dioxide and water (from aerobic respiration)
      • Urea (produced by breakdown of excess proteins, amino acids, in liver)
      • Other substances in excess (like drugs)
    • What are the dangers of waste products in humans
      • Toxicity
      • Osmotic effect
      • Using up necessary storage
    • Toxicity
      • Waste products can have toxic effects if able to reach high concentrations
    • Carbon dioxide can dissolve in water to produce an acidic solution which lowers the pH of cells.
      This can reduce the activity of enzymes in body which are essential for controlling the rate of metabolic reactions
    • Osmotic effect
      • Body fluids can become more concentrated due to higher amounts of waste products
    • Concentrated body fluids can cause water to move out of cells, changing their water potential possibly preventing them from carrying out essential reactions
    • What are the organs used in excretion
      • Skin
      • Lungs
      • Kidneys
      • Liver
    • Skin
      • Excretes excess mineral ions (sodium and water) + some urea
      • Does this via sweating
    • Lungs
      • Excretion of carbon dioxide and water
      • Does this via exhalation
      • Water in the form of vapour
    • Kidneys
      • Excretion of urea, water and excess salts
      • Does this via urine
      • Urea comes from breakdown of excess amino acids in the liver
    • Liver
      • Produces urea from amino acids
    • 2 most important features of the kidney
      • The regulation of the water content of the blood
      • Excreting the toxic waste products of metabolism
    • Waste substances that need to be removed from the blood
      • Urea
      • Creatinine
      • Excess hormones
      • Excess water
      • Ammonia
      • Uric acid
      • Excess salts/ions
    • Osmoregulation
      Process of maintaining water and salt concentrations across the membranes within the body
      (Example of homeostasis within humans)
    • What does too much water in the blood do
      • Cells swelling
      • Can lead to cell lysis (bursting)
    • What does too little water in the body do
      • Cells loose water by osmosis (become dehydrated)
      • Can result in cell death
    • Hypertonic solution
      • When red blood cells have a higher water potential than solution
      • Net movement of water out of cells
      • Cells become shrivelled
    • Isotonic solution
      • Water potential equal between solution and red blood cells
      • No net movement of water
      • Normal cells
    • Hypotonic solution
      • Red blood cells have a lower water potential than solution
      • Net movement of water into the cells
      • Cells swell and may lyse (burst)
    • 2 key functions of the urinary system
      • Filter waste products from the blood
      • Controls water levels of blood
    • How are the kidneys joined to the bladder
      With 2 tubes called ureters
    • What does the urethra do
      Carries urine to outside the body
    • Each kidney is also connected to:
      • The renal artery - comes from the aorta and delivers oxygenated blood to the kidney
      • The renal vein - delivers the deoxygenated blood from the kidney to the vena cava
    • What are the 3 regions of the kidneys
      • Cortex - outermost region
      • Medulla - inner section kidney
      • Renal pelvis - Tube linking kidney to ureter
    • What sections do nephrons contain
      • The Bowman's capsule
      • Proximal convoluted tube
      • Loop of Henle
      • Distal convoluted tubule
      • Collecting duct
    • What is the process of reabsorption of the useful substances in the blood
      1. Ultrafiltration
      2. Selective reabsorption of glucose
      3. Selective reabsorption of water and salts
    • Arterioles branch off to each nephron, where they form a bundle of capillaries (the glomerulus) inside the Bowmans capsule

      The capillaries get narrower as they get further into the the glomerulus which increases the blood pressure

      Eventually this causes smaller molecules present in the blood to be forced out of the capillaries and into the Bowmans capsule, where the glomerular filtrate is formed
    • What substances are present in the glomerular filtrate
      • Glucose
      • Water
      • Urea
      • Salts
    • Protiens and red blood cells are too large to be forced out during ultrafiltration so therefore are not present in kidney filtrate
    • How is glucose reabsorbed at the proximal convoluted tube
      • Active transport
      • Nephron has many mitochondria to help with this
      • These mitochondria provide the energy for the active transport
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