Breathing & Circulation

What do humans breathe through What do humans breathe through? L_____________ What do fish use to breathe? G______________ Amphibians breathe through their s______________ Insects breathe through h__________ in their sides

Note: Clear limewater goes milky in the presence of carbon dioxide

Breathing in and Breathing out Inhale – breathe in air Exhale – breathe out air

Structure of the Breathing System

The Breathing Mechanism

Exchange of Gas in the Alveoli Alveoli – small air sacs in the lungs There are between 200-500 million alveoli in each human lung.

Each alveolus is surrounded by lots of tiny capillaries Each alveolus is surrounded by lots of tiny capillaries. Oxygen diffuses (moves) into the blood from the alveolus and carbon dioxide diffuses from the blood to the alveolus through the very thin walls of the alveolus and capillaries

Breathing & Exercise Breathing allows us to obtain the oxygen we need for respiration Respiration – is the process in which our cells release energy from food. When we exercise our cells need more food. Therefore we need more food and oxygen. Our breathing and heart rate increase so that more oxygen can be carried by our blood to our cells and waste products i.e. carbon dioxide and water can be carried back to our lungs to breathe out.

Circulatory System William Harvey While experimenting on veins he found that blood only flows in one direction around the body. He also found that the same blood was being recirculated again and again through the heart.

Circulatory System

Adults have about 5 litres of blood flowing around their body in tubes called blood vessels. Blood is made up of: Plasma Red blood cells White blood cells Platelets Many substances are transported around your body in your blood e.g. gases, water and nutrients.

Plasma The liquid part of the blood 90% water Carries different cells Many substances dissolve in it e.g. nutrients Carries chemicals that stop us bleeding Contains chemicals that help us fight off disease Red Blood Cells -Main job is to carry oxygen gas around the body - They contain a red coloured protein called haemoglobin which contains iron They pick up oxygen in the lungs Red blood cells have no nucleus

White Blood Cells Fight diseases Attach and destroy invading micro-organisms Patrol the bloodstream and tissues looking for germs Some produce chemicals called antibodies that disable harmful invaders. Platelets Fragments of cells that help to clot the blood Clotting is important because it helps to plug wounds When blood vessels get damaged they send a signal to platelets to form a clot.

Circulation We have two circuits in our circulatory System One loop goes to the lungs from the heart b) One loop goes to the rest of the body from the heart

One side of the heart pumps blood low in oxygen to the lungs One side of the heart pumps blood low in oxygen to the lungs. In the lungs The blood collects oxygen and leaves behind carbon dioxide. This blood then returns to the heart. This oxygen rich blood is then pumped from the other side heart around the body to the cells. The cells need the oxygen for respiration.

The Human Heart

The Human Heart About the size of your fist. Acts as a pump Made of muscle tissue – cardiac muscle Pumps blood out into blood vessels called arteries which carry blood around the body. -Blood is carried back to the heart In blood vessels called veins -Valves in the heart insure blood only flows through the heart in one direction.

Blood Vessels Three Types: Arteries, Veins & Capillaries Veins – blood vessels that carry blood to the heart. Usually Carry blood low in oxygen (deoxygenated blood). Exception is the pulmonary vein which carries blood rich in oxygen.

b. Arteries – blood vessels that carry blood away from the heart. An exception is the pulmonary artery it carries oxygen poor blood (blood rich in carbon dioxide) from the heart to the lungs. c. Capillaries – Very narrow blood vessels that allow for the exchange of water, gases nutrients and waste between the blood and cells. They have walls that are only one cell thick for diffusion.

The pulse A pulse is a wave of pressure that travels along the walls of the arteries. Your heart rate is measured in beats per minute.

Dissection of a sheep’s heart