‫مدرسة المشرق الدولية‬
Mashrek International School
NAME:
CLASS: MYP 5 A/B/C/D
TOPIC: CIRCULATORY SYSTEM
DATE:
/
/ 2011
STUDY HANDOUT
CIRCULATORY SYSTEM & HEART PROBLEMS
1
UNIT QUESTION
How does our life style affect our heart?
SIGNIFICANT CONCEPTS
-
-
Describe the circulatory system as a system of tubes with a pump and valves to ensure one-way flow of
blood
Describe the double circulation in terms of a low pressure circulation to the lungs and a high pressure
circulation to the body tissues and relate these differences to the different functions of the two circuits
Describe the structure of the heart including the muscular wall and septum, chambers, valves and associated
blood vessels
Describe the function of the heart in terms of muscular contraction and the working of the valves
Investigate, state and explain the effect of physical activity on pulse rate
Describe coronary heart disease in terms of the blockage of coronary arteries and state the possible causes
(diet, stress and smoking) and preventive measures
Name the main blood vessels to and from the heart, lungs, liver and kidney
Describe the structure and functions of arteries, veins and capillaries
Explain how structure and function are related in arteries, veins and capillaries
Describe the transfer of materials between capillaries and tissue fluid
Identify red and white blood cells as seen under the light microscope on prepared slides, and in diagrams
and photomicrographs
List the components of blood as red blood cells, white blood cells, platelets and plasma
State the functions of blood:
• red blood cells – haemoglobin and oxygen transport
• white blood cells – phagocytosis and antibody formation
• platelets – causing clotting (no details)
• plasma – transport of blood cells, ions, soluble nutrients, hormones, carbon dioxide, urea and
plasma proteins
Describe the function of the lymphatic system in circulation of body fluids, and the production of
lymphocytes
Describe the process of clotting (fibrinogen to fibrin only)
AREA OF INTERACTION: HEALTH AND SOCIAL EDUCATION
In this unit you will gain insight into the circulator and lymphatic systems within the human body. You will also
be encouraged to develop a better understanding of the possible medical conditions associated with the
malfunctioning of these systems.
2
SUMMATIVE TASKS:
-
Lab investigation: Criteria D, E & F
Investigate the factors that affect the heart rate
-
Unit test: Criteria C
End unit test
Summative tasks will be given separately from this booklet
DURATION:
2 weeks
3
The circulatory system is the body's main transport system, carrying food and oxygen to the cells and taking
waste products away. It is a network of tubes called blood vessels. A pump, the heart, keeps blood flowing
through the blood vessels. There are two circulations the blood makes through the heart they are:
1. Pulmonary circulation: The circulation between the heart and the lung. Its function is to oxygenate the
blood in the alveoli.
2. Systemic circulation: The circulation between the heart and the body. Its function is to send oxygen to the
cells and remove CO2 from the cells.
The human cardiovascular system is described as a closed, double circulatory system
Figure 1: Double circulation
4
 THE HEART
The heart is a four-chambered muscular pump which pumps blood round the circulatory system. It is made of a
special type of muscle called cardiac muscle
The heart is enclosed in a protective sac of tissue called pericardium. In the inner walls there are two thin
layers of epithelial and connective tissue called the myocardium. The powerful contractions of the myocardium
pump blood through the circulatory system.
Table 1: Parts of the heart

Atria
Two upper chambers

Ventricles
Two upper chambers

Septum
The tissue which separates the chambers on the left from the ones on the right

Pulmonary vein
Blood vessel that carries oxygenated blood from lungs to left atrium

Pulmonary artery
Blood vessel that carries deoxygenated blood from right atrium to lungs

Aorta
Largest artery that carries oxygenated blood from left ventricle pushed with high
pressure to head and body

Superior
and Veins that carries deoxygenated blood from all over the body and head to the right
inferior vena cava atrium

Mitral (biscuspid) Valve on the left-hand side of the heart that is made of two parts which stops blood
flowing from ventricles back to atria (controls blood direction)
valve

Tricuspid valve
Valve on the right-hand side of the heart that is made of three parts which stops
blood flowing from ventricles back to atria (controls blood direction.

Semilunar valves
Valves that stops blood flowing backwards once forced out through aorta or
pulmonary artery or vena cava
5
Q1: Label the heart in figure 2 using the parts written in table 1
Figure 2: the structure of the heart
ONLINE ASSINMENT:
Go online and open the following website PHSchool.com then enter the following web code cbp -0371 in the
place required then print out the assessment and solve the questions. Make sure to click start to see the
animation on how the heart functions it will help you a lot.
6
Discussion questions:
1. Discuss how the circulatory system works with other systems to deliver food and oxygen to the living cells
of the body
2. Discuss how the cardiac muscle of the heart is different from other muscles found in the body.
3. Discuss how students can maintain healthy hearts and circulatory systems. Why would a balanced diet and
exercise be important?
 Coronary arteries and heart problems
Figure 3: the heart and coronary arteries
Try to answer the questions below
a) What is the function of the coronary artery?
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
7
b) Fats are component of an unbalanced diet that can contribute to a heart attack, explain how it is thought to
have this effect.
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
c) Suggest other factors apart from diet that could increase the risk of a heart attack.
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
 Heart rate and exercise
The volume of blood pumped to the lungs per minute, the cardiac output, depends on the heart rate and the
volume of blood pumped at each beat, the stroke volume. By training, the heart rate is reduced at the same time
the stroke volume increases
Pulse is the ripple of pressure on the walls of arteries causing an increase in the lumen due to heart beats.
Pulse rate increases during exercise because of the increase in rate of heart beats as a result of production of the
hormone adrenaline and control of the brain
Q1. Explain why the body needs a higher cardiac output during exercise.
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
 What controls heart beating?
The nervous system influences the heart rate, but does not directly control contractions of cardiac muscle. In
fact the heart may keep beating for several minutes after it is removed from the body. The heart can beat around
60-120 times per minute at rest depending on age. It can do that by its PACEMAKER.
The pace maker is a group of specialized cells found in the right atrium. The pacemaker sends electrical signals
through the walls of the heart at regular intervals, which make the muscle contract.
The pacemaker’s rate, and therefore the rate of the heart beat, changes according to the needs of oxygen by the
body.
8
CONTROL OF THE PACEMAKER
As adrenaline (hormone) is secreted, nerve messages to the pacemaker arrive from the brain. For example
during exercise, when extra oxygen is needed by the muscles, the brain sends messages along nerves to the
pacemaker, to make the heart beat faster, but when CO2 concentration rises in blood the pH is reduced and the
blood becomes more acidic which increases the heart beating
The function of the artificial pacemaker:
Sometime, the pacemaker stops working properly. An artificial pacemaker can then be placed in the person’s
heart which produces an electrical impulse at a regular rate of about one impulse per second. (they have to be
replaced every 10 years)
9
 BLOOD VESSELS:
The blood travels through the body in a continuous system of tubes called blood vessels. This system is so huge
that if one person’s blood vessels were stretched out straight, they would reach almost half way to the moon.
There are three types of blood vessels: arteries, veins, and capillaries. Arteries are large blood vessels that
carry the blood away from the heart. Arteries divide into smaller and smaller vessels, until they are so small
they can only be seen through a microscope. These vessels are called capillaries. There are so many of these
vessels that most living cells of the body are close to capillaries. The capillaries rejoin to form veins, which are
the blood vessels that return blood to the heart.
Figure 4: Blood vessels
Note:
Veins must overcome the pull of gravity to get the blood back to the heart. The push from the heart that propels
the blood through the arteries is no longer much of a factor.
There are two things that help to move the blood through the veins. The larger veins have one-way valves that
prevent the blood from flowing backwards. The veins are located between skeletal muscles, and when the
muscles contract, they force the blood forward through the veins and towards the heart
10
Q. Explain the relationship between the structure and function of blood vessels in table 2 below
TABLE 2:
Artery
Vein
Capillary
DIRECTION
WALLS
LUMEN
VALVES
LOOK FOR THE FOLLOWING WORDS
Q. Define Thrombosis?
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
Q. Define atherosclerosis?
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
11
 BLOOD PRESSURE:
To move the blood through this network of vessels, a great deal of force and pressure is required. The force is
provided by the heart and is at its highest when the ventricles contract, forcing blood out of the heart and into
the arteries. Then there is a drop in pressure as the ventricles refill with blood for the next heartbeat.
Doctors measure the blood pressure with a device called a SPHYGMOMANOMETER. They always measure
blood pressure in the upper arm artery. Blood pressure varies throughout the body, so a standard place must be
used so that a person’s blood pressure can be compared over time and with other people. There are two pressure
readings.
- One measures the strongest pressure during the time blood is forced out of the ventricles. This is called a
SYSTOLE
- The second reading is taken during the rest period, as the ventricles refill with blood. This reading is
called a DIASTOLE.
The numbers are written together, such as 120 over 80, which happens to be the blood pressure of a healthy
young adult.
Blood pressure will change according to the activity in which the person is engaged, such as resting, walking,
and running. People who have high blood pressure readings during periods of rest are said to have
HYPERTENSION. This can be harmful to delicate body organs, so people are advised to do things to correct
the condition. This may involve losing weight and exercising more often to return the blood pressure to normal
readings.
 BLOOD
The human body of an adult contains about 5-6 liters of blood. This blood is made of about 50% PLASMA and
the rest BLOOD CELLS
Figure 5: Components of blood
12
1. Plasma
Plasma is the straw-colored liquid in which the blood cells are suspended. Plasma transports materials needed
by cells and materials that must be removed from cells:







various ions (Na+, Ca2+, HCO3−, etc.
glucose and traces of other sugars
amino acids
other organic acids
cholesterol and other lipids
hormones
urea and other wastes
2. Blood cells: There are three kinds of blood cells in the body
a) Red blood cells (Erythrocytes) b) White blood cells (leukocytes)
c) platelets
Red blood cells are saucer shaped cells found in the plasma that carry oxygen. They are the most plentiful
blood cells found in the human body. Red blood cells are also called erythrocytes. White blood cells are used
by the blood to destroy harmful germs. White blood cells are also called leukocytes.
Platelets are smaller than red blood cells and colorless. Platelets help stop bleeding by producing blood clots
that stop blood from escaping a blood vessel.
Q1. Fill table 3 below to compare in structure and function of blood cells
Tabl3: blood cells
Red blood cells
White Blood cells
Sketch a drawing
Function
Size and shape
Nucleus presence
13
Platelets
Q1. Calculations: A millimeter of blood contains about 5 millions red blood cells (about 5.2 millions in males
and about 4.7 million cells in females) and that red blood cells outnumber WBC 1000 to 1.
1. How many white blood cells are there in a millimeter of blood?
2. If a millimeter of blood was found to have 20,000 white blood cells what might explain this increase
Show your work:
Figure 6: Blood clotting
Q2. Platelets are involved in BLOOD CLOTTING, once the tissues are injured, the platelets aids in healing
and closing the wound in this sequence. Describe how platelets aids in blood clotting?
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
14
 Lymph and tissue fluid
15
1) TISSUE FLUID
Capillaries are permeable as there walls do not fit together exactly, which makes gaps between them.
Plasma and white blood cells are continually leaking out of blood capillaries. The fluid formed out is called
TISSUE FLUID that surrounds all cells in the body
Q1. Why can white blood cells leak out of blood capillaries but red blood cells cant although they are smaller in
size?
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
Q2. List the functions of tissue fluid.
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
2) LYMPHATIC SYSTEM
There are other blood vessels in the body that don’t carry blood, they carry LYMPH. "Lymph" is a milky body
fluid that also contains proteins, fats, and a type of white blood cells, called "lymphocytes," which are the
body's first-line defense in the immune system as you have learned.
Capillaries release excess water and plasma into intracellular spaces, where they mix with lymph. Lymph flows
from small lymph capillaries into lymph vessels that are similar to veins in having valves that prevent backflow.
Contraction of skeletal muscle causes movement of the lymph fluid through valves. Lymph vessels connect to
lymph nodes, lymph organs (bone marrow, liver, spleen, thymus), or to the cardiovascular system.
At certain points in these vessels there are swellings called lymph nodes .
- Lymph nodes are small irregularly shaped masses through which lymph vessels flow. Clusters of nodes
occur in the armpits, groin, and neck. All lymph nodes have the primary function (along with bone marrow)
of producing lymphocytes.
- The spleen filters, or purifies, the blood and lymph flowing through it.
- The thymus secretes a hormone, thymosin, that produces T-cells, a form of lymphocyte.
16
HOMEWORK SERACH:
Use different sources to answer the following questions
Q1. List some of the main functions of lymphatic system?
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
Q2. Describe how are the lymphatic and circulatory system related?
………………………………………………………………………………………………………………..
………………………………………………………………………………………………………………..
Q3. If you have a sore throat because of an infection, which lymph nodes might become swollen?
………………………………………………………………………………………………………………..
17
 MULTIPLE CHOICE
1. What is the circulatory system?
A. The body's breathing system
B. The body's system of nerves
C. The body's food-processing system
D. The body's blood-transporting system
2. From what source do cells get their food?
A. Blood
B. Oxygen
C. Other cells
D. Carbon dioxide
3. Why is oxygen important to blood and to the cells?
A. Oxygen helps the blood to clot.
B. Oxygen brings food to the cells.
C. Oxygen is necessary for cell growth and energy.
D. Oxygen is not important -- carbon dioxide is the most important substance to the body.
18
4. Which type of blood vessels carries blood away from the heart?
A.Veins
B. Arteries
C. Capillaries
D. Arteries, veins and capillaries
5. What would happen to people who have an open wound and whose blood did not clot naturally?
A. They would bleed to death.
B. Nothing. Clotting is not important.
C. They would have to take special clotting drugs.
D. They would have to take regular doses of plasma.
6. What is the function of the blood vessels and capillaries?
A. They pump blood to the heart.
B. They filter impurities from the blood.
C. They carry blood to all parts of the body.
D. They carry messages from the brain to the muscles.
7. Why does blood turn dark red as it circulates through the body?
A. It starts to clot.
B. It gets old and dirty flowing through the body.
C. The oxygen in it is replaced with carbon dioxide.
D. The farther blood is from the heart, the more dark red it is.
19