The Cardiovascular System

Objectives:

-To be able to recognise the structure and function of the parts of the circulatory system

Starter

• From last lesson

• Answer the following quick questions

• Which blood cell is responsible for fighting infection?

• Which blood cell carries oxygen?

• Which part of blood is responsible for clotting?

White blood cell

Red blood cell

Platelets

3 parts of the cardiovascular system

• Blood vessels (like veins, arteries and capillaries)

• The heart

• blood

Blood vessels - arteries

• Carry blood away from the heart

• Have thick muscular walls to cope with high pressure of blood as it leaves the heart

• Divide into capillaries

Blood vessels - veins

• Carry blood back to the heart

• Have thinner walls • Wider inside than

arteries• Blood pressure is low• Muscles help push

blood along veins• Veins have valves to

stop blood flowing backwards

Blood vessels - capillaries

• Branch and spread through the body taking blood to every cell.

• Very thin and leaky walls.

• Plasma carrying oxygen, food, carbon dioxide and water can pass out of the capillaries.

• Capillaries join up to form veins.

A continuous system• The blood vessels form a continuous

system around the body.

• They carry blood through the heart twice on each complete trip around the body.

• Blood goes– To the lungs to pick up oxygen– Back to the heart for a pressure boost– Around the body delivering oxygen to cells– Back to the heart

Now colour your diagram in, red for oxygenated blood and blue for deoxygenated blood

The Heart

• The circulation of blood is pumped by the heart.

• The heart beats automatically but the rate varies with the body’s level of stress and exertion.

Some facts about the heart and blood

• The heart beats about 100,000 times each day.

• In a 70-year lifetime, the average human heart beats more than 2.5 billion times

• The adult heart pumps approximately 2,000 gallons of blood each day.

• Blood is about 78 percent water. • Blood takes about 20 seconds to circulate

throughout the entire vascular system.

External view of the heart

Left ventricle: has very thick walls; pumps blood to the body except the lungs

Left atriumHas thin walls

Valve: Stops blood going back to the left atrium

This artery carries blood around the body

This vein carries blood into the heart from the lungs

Right ventricle: has thick walls; it pumps blood to the lungs

Valve strings stop the valve turning inside out

Valve: stops blood going back into the right atrium

Right atrium: has thin walls

This vein carries blood into the heart from the body

This artery carries blood to the lungs

Blood pressure and pulse.

• The blood pressure is the force of blood per unit area as it flows through the blood vessels.

• The systolic blood pressure is the highest pressure, when the left ventricle contracts to pump blood into the arteries.

• The diastolic blood pressure is lower. It is the pressure in the arteries when the heart is relaxed and filling with blood.

• As the left ventricle contracts, surges in blood pressure cause the arteries to expand and contract. This can be felt as a pulse in the major arteries.

Blood

• Functions of blood– Carries oxygen and nutrients to all your

tissues– Removes wastes such as carbon dioxide and

urea– Transports hormones– Helps to regulate the body’s temperature and

water content

Structure of blood

Structure of bloodRed blood cells

plateletsWhite blood cells

Plasma

Copy this table

Plasma White blood cells Red blood cells Platelets

• As we go through the next few slides, fill in the information on the types of cells in the blood.

The parts of blood

• Red blood cells– Contain the red pigment

haemoglobin that carries oxygen.

– Biconcave shape increases surface area so gas exchange is more efficient.

– No nucleus so more room for haemoglobin

• Plasma– A pale yellow watery fluid

containing nutrients, hormones and proteins

The parts of blood

• White blood cells– Various shapes– Have a nucleus– Defend against infection– More wbc in blood when you have an infection.

• Platelets– Small fragments of cells involved in blood clotting.– Clotting is important in stopping the flow of blood after an

injury.

Problems with blood

• Sickle – cell anaemia• Some of the red blood

cells are shaped like sickles, meaning they don’t carry oxygen as efficiently

Problems with blood

• Trypanosomes– Parasites– Single-celled

organisms that live some of their life cycle in the blood of animals, including humans.

– Cause sleeping sickness a common disease in Africa

Quick quiz

• What is the name of the red pigment in blood?– Haemoglobin

• Which component of blood is responsible for clotting?– Platelets

• Which type of blood cell has a nucleus?– White blood cells

Quick quiz

• What are the names of the chambers at the top of the heart?– Atria

• What is the name of the small blood vessels that are spread throughout the body?– Capillaries

• Name the three parts of the cardiovascular system– Blood vessels, heart, blood