Transcript The Cardiovascular System

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
White blood cell
infection?
• Which blood cell carries oxygen? Red blood cell
• Which part of blood is responsible for
clotting? 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
This artery carries blood to the lungs
This vein carries blood into
the heart from the body
Right atrium:
has thin walls
Valve: stops
blood going
back into the
right atrium
Valve strings stop the
valve turning inside out
Right ventricle: has thick
walls; it pumps blood to
the lungs
This artery carries
blood around the body
This vein
carries blood
into the heart
from the
lungs
Left atrium
Has thin walls
Valve: Stops
blood going back
to the left atrium
Left ventricle: has
very thick walls;
pumps blood to the
body except 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 blood
Plasma
White blood cells
Red blood cells
platelets
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