Post on 02-Jan-2016
transcript
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