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14 Transport in humans
14.1 Why do we need a transport system? (Book 2, p.156)

To survive, cells must have a continuous supply of oxygen, nutrients and other useful
substances, and also a continuous removal of metabolic waste, e.g. carbon dioxide. Therefore,
a transport system is needed for multicellular organisms, such as humans.

(1)
Transport
is the process of moving substances from one place to another within
an organism.

In humans, transport is provided by the (2)
and the (3)
lymphatic
circulatory
system
system
(循環系統)
(淋巴系統).
The human circulatory system (Book 2, p.156)
The human circulatory system consists of
(5)
(4)
heart
network of (6)
blood
blood
(血液)
(心臟)
vessels
(血管)
Note:
For unicellular organisms, diffusion alone is sufficient for the transport of substances into or out of the cells.
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14.2 What makes up blood? (Book 2, p.157)

Blood is a fluid (1)
tissue
which is made up of blood cells and plasma (血漿).
 Composition of blood

It can be separated into two layers by a centrifuge (離心機). The top watery yellow layer is the
(2)
plasma
(3)
blood
while the lower dark red layer consists of all the
cells
.
blood
plasma
centrifuge
blood cells
 Centrifugation of blood
Go To …
Practical 14.1 Examination of a blood smear
(Student’s Book 2 p.157; Activity Book 2 p.109)
Note:
A centrifuge is commonly used in the laboratory to separate compounds on the basis of their molecular weight. It works
by swinging the samples in a circular motion at high speed.
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Different types of blood cells (Book 2, p.158)
Red blood cells (Book 2, p.158)

Red blood cells are of (1)
disc

biconcave
whole
shape.
They contain (2)
haemoglobin
molecules to
section
carry oxygen from the lungs to all parts of the body.

 Red blood cell
Mature red blood cells do not have any nuclei.
White blood cells (Book 2, p.158)

White blood cells are (3)

They are important in protecting us from (4)
irregular
in shape.
diseases
.
round nucleus
lobed nucleus
Lymphocyte (淋巴細胞)
Phagocyte (吞噬細胞)
 White blood cells
Blood platelets (Book 2, p.158)

Blood platelets are very small pieces of broken cells. They are (5)

They help in (6)
entry of (7)

blood
pathogens
clotting
irregular
in shape.
to stop bleeding and to prevent the
.
Blood platelets do not have nuclei as they are not cells.
 Blood platelets
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Substances transported in blood (Book 2, p.159)
(1)
Oxygen
, carbon dioxide, nutrients, urea, (2)
(3)
antibodies
hormones
, heat and
are transported by blood.
 Substances transported in blood
Go To …
Practical 14.2 Detection of the presence of glucose in plasma
(Student’s Book 2 p.160; Activity Book 2 p.111)
Section concept diagram (Student’s Book 2 p.161)
Quick check (Student’s Book 2 p.161)
14.3

What are the types of blood vessels? (Book 2, p.162)
The blood vessels are divided into
from aorta
three types:
1
(4)
Arteries
artery
(動脈)
which carry blood from the heart to
the tissues
2
(5)
capillaries
Veins
(靜脈)
which carry blood from the tissues
back to the heart
3
(6)
Capillaries
vein
(微血管)
which connect the arteries to the veins
to vena cava
 Blood vessels
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The relationship between different types of blood vessels:
aorta
branches into
arteries
(大動脈)
branch into
(動脈)
arterioles
branch into a
network of
(小動脈)
pumps blood into
heart
capillaries
(exchange of materials)
drain blood into
venae cavae
(大靜脈)
join to form

Date:
veins
(靜脈)
venules
join to form
(小靜脈)
join to form
A high blood pressure is developed in the arteries due to the pumping action of the heart.
When blood passes through the arterioles and reaches the capillaries, there is a great drop of
blood pressure due to the larger total cross-sectional area of the capillaries. The blood pressure
is even lower when it reaches the venules and the veins due to the friction of the capillary
walls.
 Changes in blood pressure along different blood vessels
Arteries (Book 2, p.163)

Arteries carry (1)
oxygenated
blood (含氧血) away from the heart (except in
the pulmonary artery).

They have a small lumen and a thick wall to
withstand high blood pressure.

 Cross-section of an artery
Blood in the arteries is moved by the pressure set up by the (2)
pumping
action of
the heart.
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Veins (Book 2, p.163)

Veins carry (1)
deoxygenated
blood (缺氧血) to the heart (except in the
pulmonary vein).

They have a large lumen to reduce resistance
to blood flow.


 Cross-section of a vein
Blood in the veins is moved mainly by the pressure on the veins from the contraction of
(2)
body
(3)
Valves
muscles
.
are present to prevent the backflow of blood and to ensure that the blood
only flows towards the heart.
 How muscle contraction helps blood flow in veins
Capillaries (Book 2, p.164)

Capillaries allow the (4)
exchange
of
very small lumen
materials between the blood and the body cells.

(5)
Branching
of capillaries greatly
increases the surface area for diffusion
one layer of cells
of materials.

Capillaries have large total cross-sectional
area which slows down the blood flow and
 Cross-section of a capillary
allows a longer time for exchange of materials.

The one-cell thick capillary wall provides a short distance for rapid diffusion of materials.
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Go To …
Practical 14.3 Examination of the transverse sections of an artery and a vein
(Student’s Book 2 p.164; Activity Book 2 p.113)
Practical 14.4 Examination of the capillary flow in a fish tail fin
(Student’s Book 2 p.165; Activity Book 2 p.114)
Quick check (Student’s Book 2 p.166)
14.4 What is the structure of a heart and how does it function?
(Book 2, p.167)

The heart is located inside the thorax between the two lungs. It is protected by the
(1)

pericardium
(圍心膜).
The heart is made up of (2)
cardiac
muscle
(心肌)
which contracts and
relaxes continuously to pump blood throughout the body.

The (3)
coronary
cardiac muscle while the (4)
arteries
coronary
(冠狀動脈)
supply oxygen and nutrients to the
veins
(冠狀靜脈)
carry carbon
dioxide and other waste away from the cardiac muscle.
 External structure of a heart
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The structure of a heart (Book 2, p.168)
A
F
B
G
C
H
D
I
E
J
 Vertical section of a heart
Structure
(1)
A
Description
Pulmonary
artery
(2)
B
Superior
vena
(3)

Carries blood from the right ventricle to the lungs

Carries blood from the head and the arms to the
right auricle

Located at the base of the aorta and the
pulmonary artery

Prevent the backflow of blood into the ventricles

Carries blood from the legs and the abdomen to the
right auricle
cava
Semi-lunar
valves
(半月瓣)
C
D
(4)
vena
(5)
E
Inferior
cava
Tricuspid
valve

(三尖瓣) 
Has three flaps
Prevents the backflow of blood from the right ventricle
to the right auricle
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Structure
(1)
Aorta
(2)
Pulmonary
veins
(3)
Bicuspid
H
valve
(4)

Carries blood from the left ventricle to the whole body
(except the lungs)

Carry blood from the lungs to the left auricle

(二尖瓣) 
(腱索)

Prevents the bicuspid and tricuspid valves from turning
inside out when the ventricles pump blood out of
the heart

Prevents the mixing of oxygenated and deoxygenated
blood
I
(5)
Septum
(隔)
J
The heart consists of the left and right (6)
(7)

ventricles

auricles
(心耳) and
the left and right
(心室).
They auricles receive blood at low pressure from the venae cavae and the pulmonary veins,
and they have a (8)

Has two flaps
Prevents the backflow of blood from the left ventricle
to the left auricle
Heart
tendon

Date:
Description
F
G
)
thin
wall.
Since ventricles contract strongly to pump blood out of the heart under high pressure, they
have a (9)
thicker
The (10)
left
whereas the (11)
wall than auricles.
ventricle pumps blood to all parts of the body (except the lungs)
right
ventricle pumps blood only in a short distance to the lungs.
Therefore, the wall of left ventricle is (12)
thicker
than that of the right ventricle.
Go To …
Practical 14.5 Dissection and examination of a pig heart
(Student’s Book 2 p.169; Activity Book 2 p.116)
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Cardiac cycle (Book 2, p.170)
The (1)
cardiac
cycle
one heartbeat. It involves a single (2)
(心搏週期)
contraction
is the sequence of events that take place in
and (3)
relaxation
of the cardiac
muscle to pump blood around the body.
1
Blood flows from the venae cavae and pulmonary veins into the relaxed right and left auricles
respectively. As the auricles contract, blood inside is pushed into the two ventricles. The
auricles then relax.
2
When the ventricles contract, blood is pumped into the pulmonary artery and the aorta
respectively. The ventricles then relax.
3
When the auricles and ventricles are in a relaxed state, blood from the venae cavae and
pulmonary veins flow into the auricles again. This completes one cardiac cycle.
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The coronary arteries and coronary heart disease

)
Date:
(Book 2, p.171)
Fatty substances deposit on the inner wall of the coronary arteries. This narrows the arteries
and slows down the blood flow. (1)
Coronary
heart
disease
(冠心病)
and eventually heart attack will result.
 Cholesterol plaque blocking the coronary arteries may lead to
a heart attack

Diets high in (2)
fats
animal
and (3)
cholesterol
,
smoking, stress and lack of exercise are
causes of coronary heart disease.
 A lot of dim-sum are high in cholesterol
Go To …
STS connection 14.1 Relationship between diet, lifestyle and the incidence of coronary heart disease,
stroke and high blood pressure (Student’s Book 2 p.172; Activity Book 2 p.122)
Quick check (Student’s Book 2 p.173)
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14.5 How is blood circulated in the body? (Book 2, p.174)

A complete blood circulation consists of both (1)
(體循環)

and (2)
pulmonary
systemic
circulation
circulation
(肺循環).
Since blood passes through the heart twice in one complete circulation, this type of circulation
is called a (3)
double
circulation
(雙循環).
Pulmonary circulation (Book 2, p.174)
The right ventricle pumps deoxygenated blood through the (4)
into the lungs. The oxygenated blood flows through the (5)
pulmonary
pulmonary
artery
veins
to the left auricle.
Systemic circulation (Book 2, p.174)
Oxygenated blood flows from the left auricle to the left ventricle, which pumps blood through the
(6)
aorta
to all parts of the body except the lungs. In the capillary beds, materials are
exchanged. The deoxygenated blood returns to the right auricle through the (7)
cavae
venae
.
Key:
pulmonary circulation
systemic circulation
L.A. = left auricle
L.V. = left ventricle
R.A. = right auricle
R.V. = right ventricle
 The human circulation plan
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14.6 How are materials exchanged between blood and the
body cells? (Book 2, p.176)

plasma in capillary
Exchange of materials between
blood and body cells takes place at
the (1)

capillaries
only.
Due to the blood pressure inside the
capillaries and the concentration
difference, useful materials are
forced out of the blood into the
tissue fluid and then diffuse into
 Exchange of materials between blood and body cells
the body cells.

tissue fluid
Waste from the body cells diffuses from the body cells into the tissue fluid and then passes
through the capillaries into the blood.
E Formation of tissue fluid (Book 2, p.176)

At the arterial end of the capillary beds, the blood pressure inside capillaries is
(2)
higher
than the pressure of the tissue fluid. Some materials are forced out of
the capillaries to form the tissue fluid.

(3)
Tissue
fluid
serves as an important bridge for the exchange of
materials between capillaries and body cells.

Plasma proteins, (4)
red
blood
cells
and blood
platelets in blood are too large to be forced out through the capillary wall. Yet, (5)
blood
cells
white
can squeeze between the cells of capillary walls and
enter the tissue fluid.

The composition of tissue fluid is similar to plasma, except that it has no
(6)

plasma
proteins
.
At the venous end of the capillary beds, the blood pressure is (7)
lower
than that
of the tissue fluid. Some tissue fluid returns to the capillaries while some is drained into the
lymph vessels.
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lymph vessel
lymphatic capillary
red blood cell
arteriole
venule
body
cell
direction of
blood flow
higher pressure
at arterial end
lower pressure
at venous end
tissue fluid
Key:
plasma forced out of the capillary to form tissue fluid
tissue fluid returned to the capillary
tissue fluid drained into the lymph vessel
 Formation of tissue fluid in the capillary bed
Go To …
Quick check (Student’s Book 2 p.177)
E 14.7 What is the lymphatic system? (Book 2, p.178)
The lymphatic system consists of (1)
(2)
lymph
lymph
vessels
with lymph nodes and the
inside.
 Lymphatic system
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1
Lymph vessels (Book 2, p.178)

(1)
Lymph
capillaries
)
Date:
are blind-ended vessels present in the capillary
beds. They join to form lymph vessels, which return the tissue fluid to the blood as lymph.

Lymph is moved along the lymph vessels:
1
By contraction of (2)
2
(3)
Valves
body
muscles
surrounding them.
in the lymph vessels prevent backflow of the lymph.
 Lymph vessel
2
Lymph nodes (Book 2, p.178)
(4)
Lymph
nodes
are swellings at intervals along the lymph vessels. Many
white blood cells accumulate there to kill pathogens. Lymph is filtered through the lymph nodes
before it is returned to the circulatory system.
E Functions of the lymphatic system (Book 2, p.179)
1
Transport of tissue fluid back into the blood.
2
Transport of absorbed (5)
3
As a site for (6)
body
fats
from lacteals in intestinal villi into the blood.
defence
.
Go To …
Section concept diagram (Student’s Book 2 p.180)
Quick check (Student’s Book 2 p.180)
Review (Student’s Book 2 p.181)
Summary concept diagram (Student’s Book 2 p.182)
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 Practice question
A heart is cut across the left and the right auricles. The diagram below shows the top view from the
cut end of one of the halves.
a
Name structures A, D, E and F.
(4 marks)
A: Tricuspid valve, D: Septum, E: Bicuspid valve, F: Semi-lunar valve. (1m x 4)
b
The blood flowing through blood vessel B has a higher concentration of oxygen than the
blood flowing through blood vessel C. Identify the two blood vessels.
(2 marks)
B: Aorta, C: Pulmonary artery. (1m x 2)
c
When the ventricles contract, what will happen to
i
structure E?
(1 mark)
Structure E will close. (1m)
ii
structure F?
(1 mark)
Structure F will open. (1m)
ii
the blood in the ventricles?
(1 mark)
The blood in the ventricles will be pumped into blood vessels B (aorta) and C
(pulmonary artery). (1m)
d
How will the function of the heart be affected if structure E cannot close completely?
(2 marks)
There will be a backflow of blood into the left auricle. (1m) The heart will become less
efficient in pumping blood to other parts of the body. (1m)
Total: 11 marks
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