Science 8

Chapter 2Circulatory System

Starter

What do you think the circulatory system is?

How do you think the systems we have already talked about relate the circulatory system?

Objectives

By the end of the lesson you should be able to: Describe the organ and vessels involved

in the circulatory system

Circulatory System Facts: Your heart pumps 4L of blood around

your body per minute! Your heart beats around 3 billion beats

during a life time! If all your blood vessels were lined up

from end to end they would be about 100 000 km in length – about 2.5 times around the Earth!

Blood

Blood is made up of 4 parts:1. Plasma: liquid2. Red blood cells: use hemoglobin to

carry oxygen and carbon dioxide 3. White blood cells: fight infection4. Platelets: help blood to clot

The Heart This is the organ involved in the circulatory

system It function is to pump blood around the

body and to the lungs It has 4 chambers, 2 on the top called atria

and 2 on the bottom called ventricles Blood travels from atria to ventricle There are valves between the atria and

ventricles to prevent the back flow of blood

The Heart!

Blood Vessels

Arteries: carry blood away from the heart Bright red oxygenated blood Thick walled and elastic

Capillaries: connect arteries to veins Very thin walls - 1 cell layer thick! Where nutrients cross to cells and wastes cross to the

blood Veins: carry blood to the heart

Blue deoxygenated blood Thinner walled than arteries and have valves to

prevent the back flow of blood

Blood Vessels

Bringing it all together!

Heart Rate Calculate your resting heart rate Run on the spot for 1 minute and

recalculate your heart rate Has it changed? Why?

Lets go outside and see if we can pump water as fast and efficiently as our hearts pump blood!

Questions1. Were you able to transfer all the water from

one bucket to another in 1 minute? Did you do this as efficiently as your heart?

2. Describe how your arm muscles felt after a minute of modeling the heart. Were you surprised by this feeling? What do you think your arm would feel like after 1 hour of pumping blood?

3. How does modeling the heart using buckets of water relate to pulse rate?

4. Sometimes a heart does not function properly. How could you change the materials used in this activity to model a heart that cannot pump enough blood through the body?