Blood Vessels

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GCSE PE
Introducing
THE CIRCULATORY SYSTEM
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LESSON OBJECTIVES

• Identify all sections of the heart
• Describe how heart acts as a pump double
  circulatory system
• Define heart rate, stroke volume and cardiac
  output
• Understanding of blood vessels
• Functions of red and white cells, platelets and
  plasma

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The heart

• The heart is a muscular pump.
• It is divided into two halves by a central
  partition called the septum.
• Atriums form the top two chambers.
• Ventricles form the bottom two chambers.

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Parts of the heart
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Parts of the heart

• Atrium
• Either of the two upper chambers of the heart
  into which blood passes from the veins. Blood
  passes from the atria into the ventricles

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Parts of the heart contd.

• Ventricle
• Either of the two lower chambers of the heart
  that contract to force blood around the
  circulatory system

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Parts of the heart contd.

• Septum
• The wall in the middle of the pump that separates
  the left side from the right. The septum prevents
  the de-oxygenated blood in the right side of the
  heart mixing with oxygenated blood in the left
  side.

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Parts of the heart contd.

• Bi-cuspid valve
• A valve in the left side of the heart that
  separates the auricle and ventricle and prevents
  blood from seeping or flowing back down into the
  ventricle. It is called the bi-cuspid valve
  because it is made up of two flaps. It is also
  called the mitral valve.

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Parts of the heart contd.

• Tri-cuspid valve
• A valve in the right side of the heart that
  separates the auricle and ventricle and prevents
  blood seeping or flowing back down into the
  ventricle. It is called the tri-cuspid valve
  because it is made up of three flaps.

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Parts of the heart contd.

• Semi-lunar valve
• These valves prevent blood flowing back into the
  heart once it has been pushed into the aorta or
  pulmonary artery.

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Parts of the heart contd.

• Pulmonary artery
• This is the only artery in the body which carries
  de-oxygenated blood, though not very far. It
  carries oxygen-poor blood from the heart to the
  lungs for a clean up.

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Parts of the heart contd.

• Pulmonary Vein
• Again, this is the only vein to carry oxygenated
  blood. It picks up where the pulmonery artery
  leaves off, carrying the blood from the lungs
  back into the heart

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Parts of the heart contd.

• Aorta
• The most well-known artery, and the largest that
  carries blood out of the heart to the other
  arteries.

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Parts of the heart contd.

• Vena Cava (pl. Vena Cavae)
• The two main veins in the body. The superior vena
  cava carries blood from the upper body to the
  heart, and the inferior vena cava carries blood
  from the lower body.

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Contractions of the heart

• When the heart contracts and pumps blood around
  the body it is called systole.
• The blood in the right ventricle goes to into the
  pulmonary artery on its way to the lungs.
• At the same time the blood in the left ventricle
  passes through the semi-lunar valves into the
  aorta and goes around the body.

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Pathway of blood around the body
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The circulation of deoxygenated blood

• The vena cava brings blood (deoxygenated blood)
  from the body into the right atrium.
• It then passes through the tricuspid value into
  the right ventricle.
• The blood pushes through the semi-lunar valves
  into the pulmonary artery and goes into the
  lungs.

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The circulation of oxygenated blood

• Oxygenated blood from the lungs passes through
  the pulmonary vein and is collected in the left
  atrium.
• It then passes through an opening between the
  left atrium and left ventricle which is guarded
  by the bicuspid valve.
• It then arrives in the left ventricle.

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Double circulatory pump system

• Pulmonary circulation carries blood from the
  heart to the lungs and back again.
• Systematic circulation carries blood from the
  heart to all parts of the body except the lungs,
  and back again. The valves prevent back flow

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Blood Vessels

• Blood vessels carry the blood from our
  hearts--------- to tissues --------- back to the
  heart
• Exam tip ! Think of the blood vessels as boats or
  ships carrying their load (blood) around the
  body.

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Arteries

• A very important blood vessel
• They are vessels that carry blood away from the
  heart !
• Exam tip Artery ---- Away

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Arteries

• Arteries carry oxygenated blood away from the
  heart to the body and are a light red in colour
• The largest artery is the ?
• Aorta
• the arteries become smaller and smaller
• The smallest are called arterioles

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• Arterioles then join up to the smallest vessels
  in the body called ?
• Capillaries
• Arteries ------ Arterioles ------ CApillaries

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The structure of Arteries

• Arteries carry blood away from the heart
• The blood is under high pressure
• Artery walls are very elastic
• They can expand to carry the blood pumped by the
  heart
• Explain why our arteries can expand

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• Artery walls can contract - they force the blood
  towards the arterioles on to the capillaries

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Capillaries

• Tiny vessels only one cell thick
• found between the arteries and veins
• where exchanges between tissue and blood occur
• Carbon dioxide dissolved food are exchanged for
  the oxygen

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• The capillary network is huge !
• In active tissues such as muscles and the brain
  it is fine and dense
• It is less dense in less active tissue
• Why do you think this is the case ?

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The structure of our Veins

• Vein --- a vessel carrying blood towards the
  heart
• The walls of veins are quite thin and non elastic
• To ensure that blood flows only in one direction
  some veins have ?
• Valves

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• The blood is at a low pressure in the veins
• At short distances along their length are valves
• It is these valves that keep the blood flowing in
  one direction only
• It is not able to flow backwards

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• Veins carry deoxygenated blood back to the heart
• This means the blood is without oxygen and a dull
  red in colour
• The smallest veins are called venules

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• They join together to form larger and larger
  veins which carry the blood back to the heart
• Deoxygenated blood enters the heart from the
  largest veins called the ?
• Superior and Inferior Vena Cava

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Test yourself !

• Blood vessels carry blood from _______ to _______
  back to _______
• Arteries carry blood ______ the heart
• Do arteries carry oxygenated or deoxygenated
  blood ?

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• What is the largest artery called ?
• What are the smallest arteries called ?
• Complete the sequence
• Arteries-------- Arterioles ________

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Test yourself !

• Veins are vessels carrying blood_____ the heart
• To ensure that blood flows in one direction some
  veins have ?
• The blood is at a ____ pressure in the veins

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• Do veins carry oxygenated or deoxygenated blood
  back to the heart ?
• Blood without oxygen is a ______ in colour
• The smallest veins are called?
• The largest veins are called?

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Blood is made up of

• Red blood cells
• White blood cells
• Platelets
• Plasma

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Red blood cells

• In one droplet of blood, there are millions of
  red blood cells. They carry oxygen around the
  body in red haemoglobin. They have no nucleus,
  leaving more space for haemoglobin.

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White blood cells

• Fight infection and disease by destroying
• Bacteria using antibodies
• Toxins using antitoxins
• Foreign microbes by consuming them

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Platelets

• Small fragments of cells with no nucleus.
  Platelets help the blood to clot at wounds this
  then turns to a scab.

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Plasma

• In the bloodstream. That includes
• Blood cells
• Digested food (eg glucose)
• Waste (eg urea, carbon dioxide)
• Hormones

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• Why is the left ventricle much thicker than the
  right ventricle?
• The reason is the difference the blood has to
  travel, one just the small distance to the lungs
  and the other all around the body.

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Cardiovascular fitness

• Cardiovascular fitness is the ability to exercise
  the body for long periods of time.
• It requires a strong heart and clear blood
  vessels to supply the muscles with plenty of
  oxygen via the blood.

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HEART RATE

• Number of times the heart beats each minute
• Average heart rate 72 bpm

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STROKE VOLUME

• The amount of blood pumped out of the heart by
  each ventricle during one contraction
• Average Stroke Volume 85ml

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CARDIAC OUTPUT

• The amount of blood ejected from the heart in one
  minute
• Cardiac output stroke volume x heart rate

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• Average Cardiac output therefore
• SV x HR
• 85ml x 72bpm
• 6120ml per minute!

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Your Task!

• Define heart rate, stroke volume and cardiac
  output and explain the effects of physical
  exercise in relation to changes.
• Gather the information from the library, internet
  or PE books.