• M• R• S• G• R• E• N

Recap

• What is respiration?• How is the movement and sensitivity of an

organism controlled?• What are the main protein molecules involved

in digestion?• What is homeostasis?• Where are nutrients absorbed from and to?

Human Physiology Lesson 21

Excretion

Waste Products

Excretory Product

Where produced

Where excreted

Excreted in

Excretory System

Kidney

• What is the job of the kidney?

• What are the name of the blood vessels that supply the kidney?

Kidney Function

• Filter the blood• Preserve water and ions

Urine

Renalvein

Renalartery

Bladder

Right kidney

Left ureter

Urethra

The Male Urino-Genital SystemThe Male Urino-Genital System

Main vein (vena cava)Main artery (aorta)

Sphincter muscle that controls the release of urine

Nephron

The Kidney

• Filter the blood• Reabsorb all of the glucose• Reabsorb the ions needed by the body• Reabsorb water needed in the body• Release urea, excess ions and excess water as

urine

The Kidneys - Internal StructureThe Kidneys - Internal Structure

CortexNephron - where blood is filtered and urine is formed. Each kidney has about one

million nephrons.

Medulla - consisting of many ‘cone-shaped’ pyramids.

Pelvis - a chamber that collects urine from the

kidney tubules andfunnels it into the ureter.

Ureter

Your kidneys ‘clean’ the blood by filtering it about 300 times a day. Millions of microscopic tubes called nephrons do this job One very highly magnified nephron is shown in this diagram...

Diagram of a Kidney Cut in HalfDiagram of a Kidney Cut in Half

Tubule(water is reabsorbed here)

Ureter(Peristalsis pushesurine to the bladder)

Bowman’s capsule(cup shaped)

Glomerulus(bunch of capillaries enclosed

by a Bowman’s capsule)

Collecting duct (Nephrons drain into here)

Renal artery(carries unfiltered blood, with waste chemicals, to the kidney)

Renal vein(carries cleaned, filtered blood, away from the kidney)

Urine(to the bladder)

Nep

hro

n

Note: the nephron is shown at anexaggerated size in this diagram.

Preserving and Releasing Water

Quick Quiz

1. Name the artery that enters the kidneys2. Name a molecule too large to fit into the nephron3. How do ions move out of the nephron?4. What is selective reabsorption?5. Where is urea produced?6. Name another molecule produced in this organ

What happens if your kidneys stop working?

3 options

• Transplant

• Dialysis machine – haemodialysis

• Peritoneal Dialysis

Dialysis TransplantsWeekly treatments, sometimes more frequent. Temporary fix

Permanent -but a chance of rejection

Diet needs to be controlled – in relation to amount of fluid, protein, salt. No high potassium foods e.g. banana

Risks associated with an operation

Shortage of dialysis machines (peritonal dialysis) www.kidneypatientguide.org.uk/site/pdanim.php

Shortage of organs of correct tissue match -in future transgenic organs may be available (BSE?)

Drugs needed while on the machine to stop blood clotting

Immunosuppressant drugs needed for life –lowers resistance to disease

Expensive, machine, nursing staff, hospital etc

Cheaper in the long run!

Dialysis V’s Transplants

Alcohol

• Effects of Alcohol

Click on the glass to find out more about these effects...

Alcohol and Health - Short Term EffectsAlcohol and Health - Short Term Effects

Move the cursor over the different areas of the body to find outmore about the long term effects of drinking alcohol...

Alcohol and Health - Long Term EffectsAlcohol and Health - Long Term Effects

Questions

• How will the kidney respond– If you drink a lot on a cold day?– If you exercise vigorously?

• How do water and urea leave the blood into dialysis fluid?

Past Paper Questions