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					i. Excretion - Objectives                                      05/09/2010 22:11:00

  Section 2: Structure and functions in living organisms
  i) Excretion - humans


  2.68 Recall that the lungs, kidneys and skin are organs of excretion (pg. 112).

  2.69 Understand how the kidney carries out its roles of excretion and of
  osmoregulation (pg. 113)

  2.70 Describe the structure of the urinary system, including the kidneys,
  ureters, bladder and urethra (pg. 113)

  2.71 Describe the structure of a nephron, to include Bowman’s capsule and
  glomerulus, convoluted tubules, loop of Henle and collecting duct (not in book)

  2.72 Describe ultrafiltration in the Bowman’s capsule and the composition of
  the glomerular filtrate (not in book)

  2.73 Understand that water is reabsorbed into the blood from the collecting
  duct (not in book)

  2.74 Understand that selective reabsorption of glucose occurs at the proximal
  convoluted tubule (not in book).

  2.75 Describe the role of ADH in regulating the water content of the blood
  (not in book)

  2.76 Recall that urine contains water, urea and salts (not in book)
2.68 Organs of Excretion                                       05/09/2010 22:11:00

  2.68 Recall that the lungs, kidneys and skin are organs of excretion.

  Ref:
  Pg. 112            10.14 Excretion if the removal of waste substances


  To do:
   Discuss the difference between ‘excretion’ and ‘egestion’.
   Make a note about the difference between ‘excretion’ and ‘egestion’.
   Beside each organ of excretion, write down what is removed from the body.
   Read the section “The Importance of Waste Removal”
  Answer the question at the end of the page.


  Excretion and Egestion


  Organs of Excretion
  There are three important excretory organs in humans that you need to know
  about.


  Skin
  Lungs
  Kidneys


  The Importance of Waste Removal
  As long as homeostasis is maintained, body cells function efficiently and the
  body stays healthy. If homeostasis is not maintained a disease may occur, if
  the imbalance is great enough it may resulting death.


  Nitrogenous waste products and carbon dioxide are poisons to the body and
  without their effective removal by the kidneys and lungs respectively, the body
  would very quickly begin to feel their effects. As soon as nitrogenous waste and
  carbon dioxide levels rise, the body’s homeostasis mechanisms ensure that the
  levels are returned to normal. If these systems fail to work then the levels of
  harmful waste products will rise and have detrimental effects on the individual.


  Explain why the removal of urea from the body is an example of excretion. (2)
2.69 Kidneys, Excretion & Osmoregulation05/09/2010 22:11:00
  2.69 Understand how the kidney carries out its roles of excretion and of
  osmoregulation

  Ref:
  Pg. 113             10.16 Urine is made by filtration and reabsorption


  To do:
   Read the section below
  Answer the five questions which follow


  The kidneys remove urea and other toxic wastes from the blood, forming a
  dilute solution called urine in the process. The two kidneys have a very
  extensive blood supply and the whole blood supply passes through the kidneys
  every 5 minutes, ensuring that waste materials do not build up.


  The kidney acts as a filtering system. As blood flows through the kidney,
  harmful waste products, such as urea are filtered out. Useful substances such
  as glucose must remain in the blood. So the kidney must be able to filter out
  some substances but ensure at the same time that other substances remain in
  the blood.


  Osmoregulation is the control of water levels within the body and the kidneys
  play a vital role in regulating the water content of the blood.


  Questions
  1     The diagram shows a water balance for a girl who spends most of the day
  working at a desk. It is not complete.
     a. Complete the diagram by writing in the volume of sweat produced. (1)
   The next day she spent much of the day training, doing many different types
   of exercise.
   b. State how each of the following would change and why it would be
   different from the previous day.
   i. The amount of water given off as sweat. (2)


   ii. The amount of water breathed out. (2)


   iii. The amount of urine passed, if she had the same water intake as on the
   previous day. (2)


   c. Which organ controls the amount of water in the body? (1)


2     The table is about waste products which are removed from the student’s
body.
Complete the table by using the correct words from the box. (4)
          amino acids    breath       circulation    digestion    fatty
          acids
          glucose     respiration       sweat        urine


          Waste            How it is produced       How it leaves the
          product                                                        body
          carbon           by                                            in
          dioxide          .....................................         .........................................
          urea             from                                          in
                           ..................................            .........................................


3    The table shows four ways in which water leaves the body, and the
amounts lost on a cool day.




   a. Fill in the table to show whether on a hot day the amount of water lost
   would be. The first answer has been done for you. (3)
       less        more       the same


   b. Name the process by which we lose water from the skin. (1)


   c. On a cool day the body gained 2550 cm3 of water. 1500 cm3 came
   directly from drinking. Give two other ways in which the body may gain
   water. (2)


4    A runner might drink a special ‘sports drink’ at intervals during a
marathon race. The table shows the substances present in a sports drink.
                                         Substance Percentage
                                         Water
                                         Sugar                     5.0
                                         Ions                      0.2
   a. Complete table to show the percentage of water in the sports drink. (1).

   b. The runner sweats and also breathes heavily during the race.
   i. Why does the runner need to sweat? (1)


   ii. Which two substances in the table are lost from the body in sweat? (1)


   iii. Which substance in the table is lost from the body during breathing? (1)


   c. How does the sugar in the sports drink help the athlete during the
   marathon? (2)


5     Each week, an athlete trains on 5 days (training days) but does not train
on the other 2 days (rest days).
The table shows how water losses from the athlete’s body are different on a
rest day from those on a training day.
                              Volume of water lost in cm3
        Method                Rest day              Training day
        Urine                 1500                  900
        Sweating              625                   2400
        Breathing             450                   1500
        Faeces                125                   120
        Total                 2700
      a. Complete the table to show the total volume of water lost by the
         athlete on a training day. (1)


      b. Explain why the athlete sweats more on a training day. (2)


      c. On a training day, the athlete needs to take in more water. Explain why
         the athlete needs to take in more water on a training day. (2)
2.70 Urinary System                                         05/09/2010 22:11:00

 2.70 Describe the structure of the urinary system, including the kidneys,
 ureters, bladder and urethra

 Ref:
 Pg. 113            10.16 The Kidneys are part of the excretory system
 Pg. 114            10.18 The Bladder stores urine


 To do:
  Label the diagram below.
  Visit the website:
 http://msjensen.cehd.umn.edu/WEBANATOMY/timed/39.htm
 Some of these labels might be difficult but you should recognise most of them.
 Answer the 2 questions
1. To find out if a person has kidney disease, a radioactive substance is
   injected into the blood going to the kidneys. A special camera is then used to
   take pictures that show the radioactive substance in the kidneys and in the
   bladder.
The drawings show some of these pictures, taken from the front, at various
times after the injection of the radioactive substance.
   a. After how many minutes did the injected radioactive substance appear in
   the bladder? (1)


   b. After how many minutes did the injected radioactive substance appear in
   the bladder? (1)


   c. Use the information in the drawings and your own knowledge to describe
   the route of excretion of the radioactive substance. (2)


2. The diagram shows a kidney with a ureter and two blood vessels.
a. Name artery A. (1)


b. What evidence from the diagram shows that A is an artery and not a
vein? (1)
2.71 Nephron                                                05/09/2010 22:11:00

 2.71 Describe the structure of a nephron, to include Bowman’s capsule and
 glomerulus, convoluted tubules, loop of Henle and collecting duct

 To do:
      Watch the animation on the whiteboard about nephron structure.
      Use the words from the learning objective to help you label the two
 diagrams below of kidney structure.
2.72 Ultrafiltration                                         05/09/2010 22:11:00

  2.72 Describe ultrafiltration in the Bowman’s capsule and the composition of the
  glomerular filtrate

  To do:
   Watch the animation on the whiteboard about ultrafiltration.
   Read the paragraph on ultrafiltration.
   Visit the website: http://www.biologymad.com/resources/kidney.swf
   From the website, for each of the following substances, follow what happens
  to it as it enters the nephron. Make a note of what happens to the substances.
   Visit the website: Target Practice.
  http://www.zerobio.com/target_practice_quiz/target_practice_quiz_kidney_ht
  m
   Answer the 3 questions


  Ultrafiltration
  The blood vessel entering the glomerulus is wider than the one that leaves. This
  raises the pressure inside the vessel to such an extent that some of the liquid
  in the blood passes out between the cells of the capillary wall. Small soluble
  molecules and ions are taken with it. The larger substances, such as blood cells
  and proteins, are too big to leave the blood capillary. The glomerular filtrate
  formed consists mainly of water, glucose, amino acids, salts and urea. This
  drains from the Bowman’s capsule into the proximal convoluted tubule.


  Notes from Website
  Urea


  Glucose


  Water


  Protein


  Sodium
Questions
1.      The diagram shows part of the urinary system.




     a. Underline the correct words to complete the following sentences.
        i. Waste urea is taken out of the body by the … renal artery / kidney /
           renal vein (1)


        ii. Urine is carried away from the kidney by the … renal artery / renal
            vein / ureter (1)


        iii. Urine is stored in the … renal vein / ureter / bladder. (1)


     b. Choose the correct word from the box to complete the following
     sentence. (1)
                       liver          lungs          stomach
        Urea is made in the ……………………………………………


2.     The table gives the amounts of some substances in blood plasma and in
urine.
                  Substance      Blood plasma       Urine
                                 (g/100 cm3)        (g/100 cm3)
                  water           92.0              95.0
                  proteins        7.3               0.0
                  urea            0.1               2.0
                  sodium ions     0.3               0.6
                  chloride ions   0.4               0.6
                  glucose         0.1               0.0
     a. Which TWO substances in the table are not excreted in urine? (1)


     b. Which organ makes urine? (1)


     c. Suggest what happens to the blood plasma if this organ stops working.
     Use the information in the table to help you. (2)


3.      The diagram shows part of the human urinary system and its blood supply.




     a. Name one useful substance carried by the blood into the kidney. (1)
b. Blood entering the kidney contains more urea than blood leaving the
kidney.
   i.    Describe, in order, the route by which urea passes from the kidney
   to outside the body. (3)


   ii.    Name liquid Y. (1)


   iii.  Put an X on the diagram in the part which contains the greatest
   concentration of urea. (1)


c. If a kidney no longer works, urea can still be removed from the body.
How is this possible? (1)
2.73 Water Reabsorption                                     05/09/2010 22:11:00

 2.73 Understand that water is reabsorbed into the blood from the collecting
 duct

 To do:
  Discuss the role of the collecting duct in water reabsorption
  Notes to be taken in class
2.74 Selective Reabsorption                                   05/09/2010 22:11:00

  2.74 Understand that selective reabsorption of glucose occurs at the proximal
  convoluted tubule.

  To do:
   Read the section below
  Answer the 4 questions which follow

  Glucose is essential for the process of respiration. This means that every cell
  in the body needs to be continually supplied with glucose. As blood undergoes
  ultrafiltartion in the glomerulus, glucose is small enough to be squeezed out
  through the capillaries during due to the high pressure.


  The body cannot afford to lose this glucose in the urine and so it must be
  reabsorbed into the capillaries. Glucose is reabsorbed in the proximal
  convoluted tubule. All of the glucose will be absorbed before the end of the
  proximal convoluted tubule in a healthy person.


  Once it is reabsorbed from the proximal convoluted tubule it will enter the
  capillaries which eventually return the blood to the renal vein.


  Questions
  1.   The diagram shows a nephron from the human kidney.




  A molecule of glucose may leave the blood in the glomerulus but then be present
  again in the blood in the renal vein. Explain how the molecule of glucose returns
  to the blood. (2)


  2.    The diagram shows a kidney nephron.
     a. Name the process taking place:
        i. in the glomerulus. (1)


        ii. between points ‘A’ and ‘B’ (1)


     b. In kidney dialysis, blood from the patient is passed into the dialyser.
     The diagram shows how urea is removed from the blood in a dialyser.




        i.     Why must the dialysate be continually replaced? (1)


        i.     Darren has been receiving dialysis since 1996. He is waiting for a
        kidney transplant. Explain how Darren’s quality of life would be improved
        by a kidney transplant. (3)


3.      The diagram shows a kidney nephron.
 A.




                                                       B.
      a. Label A and B. (2)


      b. Place X on the diagram where ultrafilteration takes place. (1)


      c. Blood is filtered as it passes through a kidney. Complete the table by
      putting YES or NO in boxes to show where each substance can be found in a
      healthy person. (4)
                          Found in
                                     filtrate in     filtrate in
            Substance     blood      first           second               urine
                                     convoluted      convoluted
                                     tubule          tubule
            protein
            water
            urea
            glucose



4.       The diagram shows a kidney nephron and its blood supply.
  P.




              Q.
                                                     R.



   a.    Label parts P, Q and R. (3)


   b.    Put an X on the diagram to show where ultrafiltration takes place.
   (1)
   c.    Samples were taken from positions A, B, C, D and E. The samples
   were analysed and the results are shown in the table.




i. Why were there no proteins in the glomerular filtrate? (2)


ii. Explain why there was glucose in the glomerular filtrate but not in the
urine. (2)


iii. Explain why the percentage of urea increased as the filtrate passed from
‘B’ to ‘C’ along the tubule. (2)
2.75 ADH                                                     05/09/2010 22:11:00

 2.75 Describe the role of ADH in regulating the water content of the blood

 To do:
  Discuss the role of ADH in regulating water content of blood.
  Take notes in class on the role of ADH and water regulation
  Answer the 6 questions


 Questions
 1.   The diagram shows a nephron from the human kidney.




    a. A molecule of glucose may leave the blood in the glomerulus but then be
    present again in the blood in the renal vein. Explain how the molecule of
    glucose returns to the blood. (2)


    b. Describe how the hormone ADH acts to reduce the volume of the
    urine.(2)


 2.    Read the passage and answer the questions that follow.
 Young people who go clubbing lose a lot of water as sweat while they dance.
 This makes them very thirsty, so they drink a lot of water. Some of them also
 take tablets called Ecstasy. Ecstasy stimulates release of the hormone ADH.
 Young people who dance a lot and take Ecstasy have very dilute blood plasma.
 When blood passes through the brain, the brain cells swell and press against the
 inside of the skull. The pressure on the brain cells causes damage, which can be
 fatal.


    a. Explain why it is important that young people sweat when dancing. (2)

    b. Name the organ that releases ADH. (1)
     c. Which organ does ADH target? (1)


     d. How does ADH travel from where it is releases to the organ it
     targets?(1)


3.    The graph shows how the mass of urea in the urine depends on the mass
of protein in the diet.




     a. Which organ in the body makes urea? (1)


     b. Explain the results shown in the graph. (3)


     c. Urine volume is controlled by the hormone ADH. ADH acts in the kidney
     on the second coiled tubule and on one other part. Name this part. (1)


     d. In hot weather we tend to produce less urine than in cold weather.
     Explain how ADH acts to decrease the volume of urine produced. (2)


4.      The diagram shows a kidney nephron and its blood vessels.
Samples were taken from each of the positions A, B, C, D and E, shown in the
diagram. Data showing the relative proportions of some substances found in the
samples are shown in the table. The samples were all of equal volume.
                      A         B           C         D          E
                      % in      % in        % in      % in       % in
                      blood     glomerul    tubule    blood      urine
                                ar
                                filtrate
           protein    6.8       0.0         0.0       6.95       0.0
           glucose    0.65      0.2         0.0       0.65       0.0
           water      89.0      97.0        95.5      90.0       97.5
           urea       0.04      0.07        1.4       0.03       2.1
     a. Put an X on the diagram to show where ultrafiltration takes place. (1)


     b. Name two structures, shown in the diagram, which must be in close
     contact to help reabsorption. (2)


     c. Explain why there is no protein in the liquid in part B. (2)


     d. Explain the changes in percentages in glucose AND urea from part B to
     part C.(4)


     e. When a person is in a very warm room, how does ADH regulate the water
     content of the blood? (2)


5.      Dave is training for a marathon.
        He does not drink enough to replace the water he loses as sweat.
        This has an effect on his body.
   a. Name hormone A. (1)


   b. What effect will hormone A have on the kidney tubules? (1)


   c. How will this affect the urine that is produced? (1)


6.     A doctor injected a radioactive substance into a patient’s blood.
Its progress through the body was followed using a radiation detector.
As it passed through the urinary system, the level of radiation was recorded.
The radioactive substance was excreted in the patient’s urine.
       The data were plotted on the graph.
The table shows the missing labels for the curves.
Write the most suitable letter, X, Y or Z, in each box. (2)


                          bladder
                          right kidney
                          blood
2.76 Urine                                           05/09/2010 22:11:00

  Recall that urine contains water, urea and salts

  To do:
  Easy one – learn the objective 

				
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