ExcretionWASTE PRODUCTS OF BODY FUNCTIONS ARE REMOVED BY THE KIDNEYS

Why do animals need an excretory system? What parts make up the excretory system? How does a kidney work? What can be done if the system does not function?

Learning Outcomes

know that the kidneys regulate the water content of the blood and remove waste products from the blood.

recognise and label a given diagram of the human excretory system to show: kidneys, renal artery, renal vein, ureters, urethra, bladder.

Excretion

Waste products made in our cells need to be removed or they would poison us. This is excretion.

In the liver excess amino acids are broken down to make urea.

The urea is taken from the liver to the kidneys, where it is excreted.

The diagram below shows the excretory organs in our body.

The Kidneys

Pupil Activity

Colouring in sheetThe Urinary System

• Colour in the diagram• Answer the questions

The Kidney

Kidneys help to maintain the internal environment by: - Filtering the blood Reabsorbing all the sugar Reabsorbing the dissolved ions needed

by the body Reabsorbing as much water as the

body needs Releasing urea, excess ions and excess

water as urine

Learning Outcomes

know that the waste, a solution containing urea and excess salts called urine, passes from the kidneys in the ureters to the bladder where it is stored before being passed out of the body.

Interpret data about the level of substances present in urine and during passage through the kidney.

observe gross structure of a section through a kidney

recognise and label a given diagram of a section through a kidney to include: cortex, medulla, pelvis, ureter and position of nephrons

Pupil activity

Biology Foundations pages 82 – 83Cleaning blood and balancing

water – your kidneysAnswer questions 1 – 4, 7

Copy and complete the “what you need to remember” sentences

Pupil Activity – Kidney Dissection Watch the demonstration on dissecting

a kidney.

In groups – dissect a kidney – try to identify all areas labelled in the diagram – medulla, cortex, pyramid, pelvis, ureter.

You must wear safety goggles and a lab coat, and wash hands with anti-septic handwash once finished.

Learning Outcomes

recognise and label a given simplified diagram of a nephron and its associated blood supply to show: capillary knot, Bowman's capsule, tubule, collecting duct, capillary network.

understand the process of filtration under pressure

know that selective reabsorption of glucose, some salts, and much of the water takes place in the tubule.

The Nephron

As the blood passes through the capillary knot it is filtered, small molecules, urea, glucose, salts and water, pass out the capillary into the nephron

The glucose, water and some of the salts are needed by the body and are reabsorbed back into the blood from the nephron.

The urea and waste salts left are dissolved in water to form urine. It flows down the ureter to the bladder.

The “cleaned” blood leaves the kidneys in the renal vein

Activity

Complete the diagram handed out on the structure of the nephron

Pupil activity

colour in the formation of urine sheet.

Answer questions 1 – 9• TRY ANSWER ALL QUESTIONS – information

needed should all be on the side of the sheet that you coloured in!!

• Do not write on the sheet – write out full sentences into your book!!

• You have 25 minutes to complete this activity

Learning Outcomes

know that the kidneys regulate the water content of the blood by producing dilute urine if there is too much water in the blood or concentrated urine if there is a shortage of water in the blood.

ADH

ADH is a hormone, which controls the amount of water reabsorbed from the nephron.

ADH is produced by the pituitary gland in the brain.

Control of water contentThe effect of ADH on the kidney

Normal blood water level

Increase in water level

Detected by the pituitary gland

Less ADH released into the blood stream

Less water reabsorbed by the nephron

More dilute urine produced

decrease in water level

Detected by the pituitary gland

more ADH released into the blood stream

More water reabsorbed by the nephron

Small amount of concentrated urine produced

Tinkle Testing

Practical LessonAim: to analyse urine samples and to draw conclusions from the results

Urine Samples

Forensic scientists and doctors can discover a lot about someone from their urine, including kidney disease, diabetes and drug abuse.

Urine sampling in sports

Monitor hydration levels Test for doping

Urine Chart

Fluid loss has a negative effect on performance

Sweat loss varies between different sports

Progress Questions

Define the term homeostasis. What is urea? Where is it made? What is ultrafiltration? Where does it

occur? What is selective reabsorbtion? What are the differences in

composition between blood entering and leaving the kidney?

What is ADH? Where is it produced? What is it’s function?

Progress Questions - 2

What would be the effect on the volume and concentration of urine of drinking a lot of fluid on a cold day?

Explain why the regulation of water content of the blood is an example of negative feedback!

If a person has kidney failure, how can they be kept alive?

Pupil activity

ExtensionHandout – the kidneys and urinary

system• Answer questions 1 – 7

Homework colour in the formation of urine

sheet.Answer questions 1 - 9

Kidney Disease

Treatment of kidney disease using kidney dialysis or kidney

transplants!

Learning Outcomes

know that kidney failure may be treated by a transplant or by a dialysis machine and compare the advantages and disadvantages of the use of these methods

know that a diseased kidney may be replaced by a healthy one by transplant from a donor of a similar 'tissue type' to the recipient. The donor kidney may be rejected, attacked by the immune system, unless anti-rejection drugs are taken.

Learning Outcome

understand that in a dialysis machine a person's blood flows between selectively permeable membranes.

Dialysis in the Kidney

Kidney Dialysis

Dialysis removes substances from a solution by diffusion

This principle is put to use in a kidney dialysis machine

Kidney Dialysis - machine

Kidney Dialysis machine

In a dialysis machine a person's blood flows between selectively permeable membranes.

It is important that useful substances in the blood, such as glucose and salts, are not lost.

To prevent this the dialysis fluid contains the same concentration of these substances as blood plasma.

This ensures that only urea and excess salts and water diffuse into the dialysis fluid.

This treatment has to be carried out at regular intervals

Transplants Vs Dialysis

Advantages Normal lifestyle

Dialysis machine available for others to use

Dialysis machines expensive to buy and maintain

Disadvantages Requires a suitable

donor (tissue match)

Operation is expensive

Risk of rejection of transplanted kidney (use of immunosupressor drugs)

Religious beliefs