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Site author Richard Steane
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THE HEART AND CIRCULATORY SYSTEM

Many more hearts and
other anatomical models
available online
via this link
In Man and all mammals, the heart is a double muscular pump. The right side pumps deoxygenated blood from the body to the lungs, and the left side pumps oxygenated blood from the lungs to all parts of the body.


Each side consists of 2 chambers: the upper thin walled atria (singular - atrium) act as receiving chambers and the lower chambers, called ventricles, have thicker walls, because they actually do most of the pumping, by contraction.

Valves between the atria and the ventricles, and in the outflow from the ventricles, keep blood flowing in the correct direction.

Label this diagram of a cross-section through the heart, and insert arrows to show the flow of blood:

Heart


Why are the parts on the left of the diagram labelled as right, and vice versa?

> inversion as in a mirror - looking at the position as in the body

Why is the wall of the left side of the heart somewhat thicker than on the right side?

> it has to work harder, to produce more pressure, to take blood all round the body, to the head and above

Heart showing coronary arteries What are the names of the 2 blood vessels running down over the outside of the heart?

>coronary artery >coronary vein

What does each of these blood vessels carry?

>oxygenated blood >deoxygenated blood

The circulatory system


The heart is attached to a series of tubes called blood vessels. There are three types of these: arteries, capillaries and veins. Each type has a slightly different structure, according to the function it has to perform.

COMPLETE THE TABLE BELOW

NOTE: EACH IS A CONSEQUENCE OF THE ONE BEFORE

Types of Blood Vessel

Notes Arteries
artery
Capillaries
capillary
Veins
vein
blood direction away from heart between arteries and veins towards heart
blood pressure > high - nearest to heart gradually runs from high to low > low - "used up"
wall structure > muscle and elastic layers > single cell thickness > muscle and elastic layers
wall thickness > thick > single cell thickness > thin
internal diameter (also known as lumen, or bore) >narrow; >very narrow - down to size of red cell > wider
valves present? > no > no > yes
blood type,
i.e state of oxygenation
(usually) > oxygenated
exception:pulmonary artery
makeup of blood alters gradually, e.g. oxygen taken out or absorbed (usually) > deoxygenated
exception: pulmonary vein
The blood inside veins running alongside muscles is encouraged to flow by the massaging effect of the muscles, and valves ensure that this flow is always back towards the heart.

veins alongside muscle

What causes (i.e. what gives the power for) the pulse you can feel at your wrist, for example?

> heart muscle contracting

What sort of thing is expanding when you feel the pulse?

> artery - not vein

The pattern of the circulatory system

Complete the following simplified diagram of the circulatory system, by drawing blue or red lines and arrows.

The "Main artery" is called the aorta, and the "main vein" is called the vena cava.

Also label these blood vessels.

Cirbar
What do the different colours represent?

blue:> deoxygenated blood (blood with extra CO2)

red: >oxygenated blood


Blood enters and leaves most organs via a pair of blood vessels (artery and vein) which are named according to the organ.

What do you think is the name of the blood vessel bringing blood into the lungs?

>pulmonary artery

The hepatic portal vein is an exception, taking blood from the digestive system to the liver.

In what way do you expect that this blood may differ from other blood in the body?

>extra products of digestion (glucose, amino acids etc.)

Label the following on the diagram above: blood vessels leading to and from the lungs, liver, digestive system, and kidneys.


Heart models available online



Many other anatomical models and charts available by following this link.



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