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TRANSPORT SYSTEMS IN MAMMALS (HUMAN)
Here are some important terms:
1. Deoxygenated
2. Oxygenated
3. Bicuspid valve
4. Tricuspid valve
5. Aorta
6. Pulmonary vein
7. Pulmonary artery
8. Superior vena cava
9. Inferior vena cava
10. Vertical septum
11. Semi lunar valves
12. Lymph
13. Tissue fluid
14. Double circulation
15. Pulmonary circuit
16. Systemic circuit
TERMINOLOGY
1. Blood which has more carbon dioxide than oxygen.
2. Blood that has more oxygen than carbon dioxide.
3. Valve that is found between left atrium and ventricle
4. Valve that is found between right ventricle and atrium.
5. Large artery that carries oxygen blood out of the heart to all parts of the body.
6. Artery that carries deoxygenated blood from heart to the lungs
7. Vein that carries oxygenated blood from the lungs to the heart
8. The vein that carries deoxygenated blood from the upper parts of the body to the right atrium of the heart.
9. Vein that carries deoxygenated blood from the lower parts of the body to the right atrium of the heart.
10. Tissue that separates the heart into right and left halves.
11. Valves found at the entrance of blood vessels to prevent the backflow of blood.
12. Tissue fluid that enters the lymph vessels
13. Circuit of blood that flows from the heart to the lungs and back to the heart
14. Circuit of blood from the heart to all parts of the body and back to the heart.
SOLUTION
CIRCULATORY SYSTEM
The blood circulatory system is made up of the:
1. The heart
2. The blood vessels
Location:
The heart is found in
the middle of the
thoracic cavity within
the ribcage.
It lies behind the
sternum and points to
the left.
Diagram to show the location of human heart
THE HUMAN HEART
The heart is enclosed within a double walled sac called the pericardium.
There are a large number of blood vessels that enter and leave the heart.
The superior and inferior vena cava and the pulmonary veins enter the heart.
The aorta and the pulmonary arteries leave the heart.
The coronary arteries and veins supply and drain the heart muscle itself.
EXTERNAL STRUCTURE OF THE HEART
The heart is separated into right and left halves by the
vertical septum.
Each half is further divided into an upper and lower portion.
The two upper portions are called the atria or atrium.
The two lower portions are called the ventricles.
Therefore there is a right and left atrium and a right and left
ventricle.
The atria and ventricles are separated from each other by
valves.
The bicuspid or mitral valve separates the left atrium from
the left ventricle.
The bicuspid valve has 2 cusps.
The bicuspid valve prevents the blood from flowing back into left
atrium when the ventricle contracts.
The right atrium is separated from the right ventricle by the tricuspid valve.
The tricuspid valve has 3 cusps.
The tricuspid valve prevents the blood from flowing back into the right atrium when the right ventricle contracts.
Walls of the atria are much thinner than the walls of the ventricles.
This is because the atria pump blood only to the ventricles while the ventricles pump blood much further.
Thickness of the walls of the heart is associated with the distance the blood is
pumped.
The thickness of the wall determines the amount of pressure that is created in the blood.
The thicker the wall the more the pressure and the further the blood can travel.
BLOOD VESSELS THAT ENTER AND LEAVE THE HEART.
Remember deoxygenated blood refers to
blood that has more carbon dioxide
than oxygen.
Oxygenated blood is blood that has more
oxygen than carbon dioxide.
The veins bring blood to the heart .
Arteries carry blood away from the heart.
The superior vena cava carries deoxygenated
blood from the upper parts of the body to the
right atrium.
The inferior vena cava carries deoxygenated
blood from the lower half the body to the right
atrium.
The pulmonary artery carries deoxygenated
blood from the right ventricle to the lungs.
BLOOD VESSELS THAT ENTER AND LEAVE THE HEART.
The pulmonary veins carry oxygenated
blood from the lungs to the left atrium.
The aorta carries oxygenated blood
from the left ventricle to all parts of
the body.
The coronary artery is a branch of the
aorta and carry food and oxygen to
the heart muscle.
The coronary veins carry the metabolic
waste and deoxygenated blood away
from the heart muscle.
BLOOD VESSELS THAT ENTER AND LEAVE THE HEART.
Copy this table showing the different blood vessels found in the heart and complete it.
Name of blood vessel Type of blood carried Where the blood comes from?
Where the blood vessel goes to?
Pulmonary vein lungs enters left atrium of heart
deoxygenated left ventricle the lungs
Superior vena cava deoxygenated
deoxygenated lower parts of body right atrium
Aorta
Table showing the different blood vessels found in the heart.
Name of blood vessel
Type of blood carried
Where does the blood come from?
Where does the blood go to?
Pulmonary vein oxygenated lungs The left atrium of the heart
Pulmonary artery
deoxygenated Right ventricle The lungs
Superior vena cava
deoxygenated The upper parts of the body
The right atrium of the heart
Inferior vena cava
deoxygenated The lower parts of the body
The right atrium of the heart
Aorta oxygenated Left ventricle of the heart
All parts of the body
SEMI LUNAR VALVES
The aorta and pulmonary arteries have a special valve at
their entrance.
These valves are called the semi lunar valves.
These valves have 3 cusps and are semi circular in shape.
Function: to prevent the blood from flowing back into the
ventricles.
On the diagram all 3 valves are visible.
Observe the number of cusps or flaps and the shape of the flaps.
Try to remember the function of each valve.
Tabulate the structural and function differences between the three types of valves in the heart. (6)
Bicuspid Tricuspid Semi lunar (√)
1. Found between the left atrium and ventricle
1. Found between the right atrium and ventricle.
1. Found at the entrance of the aorta and pulmonary artery. (√)
2. Made up of 2 flaps 2. Made up of 3 flaps 2. Made up of 3 flaps(√)
3. Prevents oxygenatedblood from flowing back into the left atrium when the left ventricle contracts
3. Prevents deoxygenated blood from flowing back into the right atrium when the right ventricle contracts.
3. Prevents the blood from falling back into the ventricles. (√)
A healthy heart beats about 70 times per minute. A single heart beat is also called a cardiac cycle. A complete heart beat lasts about 0.8 seconds. Each cardiac cycle is controlled by the SA node. The SA node is a natural pacemaker, it is found in the right
atrium. A single heart beat or cardiac cycle is made up of 3 phases. These 3 phases are:◦ Atrial systole: which occurs in about 0.1 seconds.◦ Ventricular systole: which occurs in about 0.3 seconds.◦ Diastole: which occurs in about 0.4 seconds.◦ Systole refers to a contraction of the heart muscle.◦ Diastole refers to a relaxation of the heart muscle.
The events that occurs during this phase:
1. Both the atria contract.
2. Both the ventricles relax.
3. The tricuspid and bicuspid valves open.
4. The semi lunar valves close.
5. Deoxygenated blood is forced from the
right atrium to the right ventricle.
6. Oxygenated blood is forced from the left
atrium into the left ventricle.
1. Both the ventricles contract.
2. Both the atria relax.
3. Tricuspid and bicuspid valves close.
4. Both semi lunar valves open.
5. Deoxygenated blood is forced from the
right ventricle into the pulmonary artery.
6. The pulmonary artery carries the blood
to the lungs.
7. Oxygenated blood is forced from the left
ventricle to the aorta.
8. The aorta carries this blood to all parts of
the body.
1. Both the ventricles and atria relax.
2. Tricuspid and bicuspid valves are
open.
3. Both semi lunar valves are closed.
4. Oxygenated blood from the lungs
enters the left atrium of the heart
via the pulmonary veins.
5. Deoxygenated blood from all parts
of the body enters the right atrium
via the superior and inferior vena
cava.
Use the diagrams as a
guide to discuss the
events of the cardiac
cycle in detail under
appropriate headings.
Humans have two circuits of blood flow. This is called double circulation. This means that blood flows in two different directions at the same time.These two circuits of blood flow are :a) The pulmonary circuit. b) The systemic circuit.In the pulmonary circuit blood flows from the heart to the lungs and back to the heart.In the systemic circuit blood flows from the heartto all parts of the body and back tothe heart.
Draw flow diagrams to show double circulation.
The following occurs:
Deoxygenated blood from the right ventricle is forced into the pulmonary artery.
The pulmonary artery branches as it leaves the heart and one branch enters each lung.
In the lung the artery branches and rebranches until it forms tiny capillaries.
These capillaries carry the deoxygenated blood to the alveoli.
The carbon dioxide diffuses out of the capillaries into the alveoli.
Oxygen then moves out of the alveoli and into the capillaries.
The blood in the capillaries is now oxygenated
The capillaries join and rejoin to form larger and larger veins as they leave the lungs.
These veins leave the lungs as the pulmonary veins
The pulmonary veins from each lung enters the left atrium of the heart.
The systemic circuit is a much larger and more complicated circuit.
It is made up of a number of smaller circuits.
Oxygenated blood from the left ventricle is forced into the aorta.
The aorta leaves the heart carrying the oxygenated blood.
The aorta branches and rebranches until it forms smaller arterioles that carry oxygenated blood to all parts of the body.
These arterioles branch and branch until they form capillaries that supply the cells in the all parts of the body with oxygen.
Oxygen moves out of the capillaries into the cells and carbon dioxide moves out of the cells and into the capillaries.
The blood in the capillaries is now deoxygenated.
The capillaries from the lower half of the body join and rejoin to form veins .
The largest of these veins is the inferior vena cava that carries the deoxygenated blood to the right atrium of the heart.
The capillaries in the upper half of the body join and rejoin to form bigger and bigger visions.
The largest vein is the superior vena cava that carries the deoxygenated blood from the upper half of the body to the right atrium of the hear.
HEPATIC PORTAL SYSTEM
The hepatic portal circuit is a branch of the systemic circuit.
The hepatic portal vein carries blood rich in digested nutrients to the
liver.
In the liver the excess glucose is converted to glycogen and stored.
The rest of the blood leaves the liver via the hepatic vein.
The hepatic vein joins the inferior vena cava.
Can you explain the movement of the blood from the time it leaves
the liver until it reaches the right atrium of the heart?
During strenuous physical activity the carbon dioxide content of the body increases.
The special receptors in the carotid arteries become stimulated.
They send messages to the medulla oblongata of the brain.
The medulla oblongata sends messages to the heart and
breathing muscles
The sympathetic nerves causes heart to beat faster taking
deoxygenated blood to the heart at a faster rate.
The breathing muscle causes inhalation and exhalation to
occur at a faster rate
Both the above action causes the excess carbon dioxide to
leave the body at a faster rate and oxygen to enter the body
at a faster rate.
In this way the carbon dioxide levels in the body return to
normal.
Once you have completed exercising the parasympathetic
nervous system slows down the heart rate.
Arteries carry blood away from the heart to the
organs and limbs of the body.
They have thick elastic walls because arteries
must be able to stretch when blood is pumped
into them by the heart.
The blood surges with each heartbeat.
This pulse can be felt where an artery runs near
the surface of the skin or over a bone.
Arteries divide into thinner vessels, arterioles,
These arterioles branch to form a dense network
of capillaries in the body organs.
BLOOD VESSEL: ARTERIES, VEINS AND CAPILLARIES.
Veins have thinner less elastic walls than arteries.
They provide a wider passage for blood flow.
As the blood pressure is very low in veins blood
could flow backwards.
To prevent the blood from flowing backward
veins have a system of one way valves that prevent
the backflow of blood.
When the blood flows backwards the valves close
to prevent this.
VEINS
Capillaries are thinner than a human hair.
Their walls are only one cell thick, with spaces between the cells so
that plasma and white blood cells can pass through.
Plasma carries dissolved food and oxygen directly to the tissue cells,
and carbon-dioxide and other waste products are carried away.
Blood flow slows down in the capillaries so that this exchange has
more time to take place between tissue fluid and the capillary.
Red blood cells do not leave the capillaries.
Capillaries join to form wider vessels called venules which then
become veins.
CAPILLARIES.
SOMETHING FOR YOU TO DO
Use a table to compare the structure and function of the
three different blood vessels you have studied.
Blood in the capillaries are under a great deal of pressure.
The pressure forces some of the blood
plasma out of the capillaries.
The blood plasma surrounds the cells
and is now called tissue fluid.
Some of this tissue fluid would enter the lymph vessels and is now called lymph.
Some tissue fluid re enters the blood
capillaries and is more blood plasma.
Lymph capillaries are blind-ended thin walled vessels.
•These lymph capillaries are found in all tissues except the brain and spinal cord.
•The lymph capillaries rejoin to form lymph venules.
•These lymph venules join to form lymph ducts .
•The largest of these lymph ducts are the left thoracic duct and the right lymphatic duct.
•The left thoracic duct drains lymph from the whole body and returns it to the left subclavian vein.
•The right lymphatic duct drains lymph from the upper right portion of the body and pours this lymph into the right subclavian vein.
•The subclavian returns the lymph to the right atrium of the heart
•The lymphatic system helps to return fluid to the heart.
FUNCTIONS OF LYMPHATIC SYSTEM
• Helps return fluid to the heart.
• The lacteal, which is the lymph vessel inside the villi or the intestines, helps in the absorption and transport of fat around the body
• Lymph glands or lymph nodes play a vital role in destroying diseases. If you have a sore throat, the glands in your neck swell to indicate infection.
SOMETHING FOR YOU TO DO:
Differentiate between the blood, tissue fluid
and lymph.
SOLUTION
Diseases of the cardiovascular system can be serious and are a major cause of death, seeing as blood is the manner in which all your cells in the body receive useful substances and get rid of waste products.
Sometimes causes are genetic, but lifestyle is also a major contribution to diseases and disorders. These are smoking, drinking, lack of exercise, obesity etc.
EXAMPLES OF DISEASES AND DISORDERS
Anaemia
When a person has too few red blood cells due to a lack of iron. The person appears pale with no energy.
Leukaemia
A type of blood cancer that causes uncontrolled division of the leucocytes (white blood cells).
Blood pressure
Hypertension is high blood pressure and hypotension is low blood pressure. In high blood pressure, the heart has to work harder, which can lead to stroke, heart attack or kidney disease. In low blood pressure, a person feels dizzy and has fainting spells.
Angina, arteriosclerosis
Angina is chest pain associated with too little oxygen being delivered to the heart muscles. This can be associated with arteriosclerosis which is a narrowing of the arteries due to arteriosclerotic plaque.
Heart attack and strokes
In a heart attack, the coronary arteries, supplying oxygen to the heart, become blocked or they spasm. The heart no longer has enough oxygen to work and stops pumping.
In a stroke, a clot may form and block one of the arteries to the brain, starving it of oxygen, or a blood vessel may burst as a result of a blockage or hypertension and weakening of the artery walls.
