excretion - wikispaces what is excretion? ... to form carbonic acid. ... accumulation of wastes is...
TRANSCRIPT
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Lesson 1
Learning Objective1.Define excretion as the removal of toxic
materials and the waste products of metabolism from organisms.
Outline What is excretion? Excretory products Excretory organs
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What Is Excretion?
Excretion is the removal of toxic materials and the waste products of
metabolism from organisms.
METABOLISM = ANABOLISM + CATABOLISMMETABOLISM = ANABOLISM + CATABOLISM
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Excretion is NOT egestion
Excretion is the removal of toxic materials and the waste products of metabolism from organisms.
Egestion is the removal of undigested food matter from the alimentary canal.
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Excretory Products
1.Carbon dioxide– Produced as a waste product of respiration– It is harmful because it is an acidic gas, that can slow
down enzyme reaction.
2.Excess water– Excess water– Comes from eating, drinking– Produced as a waste product of respiration– It is harmful because it can cause cells to swell and
burst.
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3. Urea– Produced from the breakdown of amino acids
(deamination)– It is harmful because it is a toxic nitrogenous waste
and can prevent enzyme reaction from taking place.
4. Bile pigment (bilirubin)– Produced from the breakdown of haemoglobin– It is harmful because bile pigment is toxic.
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Excretory Organs
Carbon dioxide
Excess water
&
excreted mainly through
excreted mainly through
also through
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Exercise
1. What is excretion?2. What is the gas produced during respiration?3. Why is this gas harmful?4. Name the process that produce urea in the liver.5. Bile pigment is the breakdown of __________.6. Another name for bile pigment is __________.7. What is the main excretory organ for excess water?8. What are the other excretory organs for excess water?9. What is the excretory organ for carbon dioxide?10. Defaecation is the removal of faeces. Is it excretion/egestion?
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Lesson 2
Learning Objective1.Describe the removal of carbon dioxide from the
lungs2.Identify on diagrams and name the kidneys,
ureters, bladder, urethra and state the function of each.
Outline Removal of CO2 from the lungs Urinary system
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Removal of CO2 from the lungs
Cell Transport system
Alveoli(Lungs)
Cell respire aerobically
to produce CO2. CO2 diffuses into
the blood.
CO2 enters red blood cells. CO2 reacts with water to form carbonic
acid. Carbonic acid breaks down into
hydrogen carbonate ions. Hydrogen carbonate ions
diffuse out into the plasma.
Hydrogen carbonate ions diffuse back into the red blood cells where they
are converted into carbonic acid and
then into water and CO2. CO2 diffuses
out of blood capillaries into the alveoli and out of
the lungs
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Urinary System
Renal artery brings oxygenated blood containing urea and excess water to the kidneys.
Renal vein brings deoxygenated blood from the kidneys. Urinary sphincter controls the discharge of urine into the urethra
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Lesson 3
Learning Objective1.Identify how a nephron works.
Outline Structure of kidney Structure of nephron Urine formation
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Urine Formation2 Stages
Stage 1: Ultrafiltration
High blood pressure in the glomerulus forces small
dissolved substances in the blood such as water, urea,
glucose, amino acids, mineral salts out of the
blood into the Bowman's capsule.
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Stage 2: Selective Reabsorption
Glucose, amino acids, useful mineral salts and useful water are reabsorbed back into the blood capillary. Glucose and amino acids are reabsorbed by active transport whereas
water is reabsorbed by osmosis.
Proximal convoluted tubule
Blood capillary
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Excess water, excess mineral salts and nitrogenous wastes (e.g. urea) pass out of the collecting duct as urine.
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Constituents of urine...can vary depending on diet.
Constituents of urine...
High Salty Diet Higher Salt Concentration in Urine
High Fluid Intake Dilute Urine
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Discussion
On a hot day, a person consumed only meat before a day of energetic work. Explain the likely changes in the composition of the person's urine
during the day.
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Essay Assignment
Describe what could happen to an amino acid molecule from the time it enters the liver to the time its component elements leave the body.
(7)
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Function of Kidney
As an excretory organ
To remove excess water
and urea from the blood
As an osmoregulator
To control the water potential
of the blood
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Discussion
• How does kidney control the water potential of the blood?
• Why is it important to control the water potential of the blood?
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Kidney as an Osmoregulator Water potential of the blood is controlled by the
amount of water reabsorbed at the Henle's loop. When water potential of blood is high, less water is
reabsorbed at Henle's loop. When water potential of blood is low, more water is
reabsorbed at Henle's loop. A hormone called anti-diuretic hormone (ADH) is
responsible for controlling the amount of water reabsorbed at the Henle's loop.
More ADH secreted More water reabsorbed. Less ADH secreted Less water reabsorbed.
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Discussion
A person drinks a lot of water. State what happen to urine volume and its concentration. Give
reasons for your answer.
Include secretion of ADH and water reabsorption at Henle's loop in your answer.
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Lesson 5
Learning Objective1.Describe dialysis in kidney machines.
Outline Kidney Failure Kidney Dialysis
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Kidney Failure
Several causes: Diabetes Hypertension Inherited kidney disease Kidney stones Infection Abuse of painkilling drugs
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Kidney Failure Kidney failure causes wastes like urea to
remain in the blood system. Accumulation of wastes is toxic to the human
system. If not treated, it could be fatal. The treatments available are either dialysis or
kidney transplant.
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Kidney Dialysis
Dialysis machine mimics the function of
kidney. It removes excess salts and
nitrogenous waste (e.g urea) from the
patient's blood.
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• The patient’s blood is made to pass through the partially permeable tube, immersed in dialysis fluid (has the same concentration as ordinary plasma)
• Small molecules such as urea and other waste products in the blood diffuse out of the tube into the dialysis fluid.
• Large molecules such as blood cells and proteins remain in the tube.
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• The tube is narrow, long and coiled to increase the surface area to volume ratio for faster diffusion.
• The direction of the blood is opposite to the flow of dialysis fluid. This is to maintain diffusion gradient.
• The filtered blood is then returned to a vein in the patient’s arm.
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Discussion
Kidney dialysis removes urea and excess salts from the blood. To be able to carry this function, the composition of the dialysis fluid
has to be regulated. Suggest the concentration of urea and salts in the dialysis
fluid.
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Exercise
1. What is the function of ureter?2. What is the function of urethra?3. Where is urea produced?4. Name the main regions of kidney.5. Name 2 stages in urine production.6. Name 2 substances that formed filtrate.7. Name 2 substances that are reabsorbed into the blood
capillary at the proximal convoluted tubule.8. High intake of protein will increase the concentration of
___________ in the urine.
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9. What are 2 functions of kidney?10. What happen to red blood cell if the water potential of blood
plasma is high?11. Where does osmoregulation takes place in the nephron?12. Name the hormone that controls water absorption in the
nephron.13. Where is this hormone secreted?14. If more ADH is secreted, __________ (more/less) water is
reabsorbed.15. What happen to ADH secretion, if a person drinks a lot of
water? Explain.