The circulatory system transports blood throughout the body via arteries, veins and capillaries. Blood carries oxygen, nutrients, hormones and waste products. The heart pumps blood through two circuits - pulmonary circulation to the lungs and systemic circulation to the rest of the body. The document provides details on the structure and function of the heart, blood vessels, blood composition and the importance of blood donation.

1. 1
FORM 3 SCIENCE NOTES
CHAPTER 2 BLOOD CIRCULATION AND TRANSPORTATION
2.1 The Transport System in Human Beings
 Internal transport system is needed to deliver useful materials to body cells and remove waste
materials from them.
 Internal transport system is called circulatory system because useful materials as well as waste
materials circulate the body.
 4 basic characteristics of circulatory system:
- Circulating fluid (Blood)
 Transports useful and waste materials.
- Pumping device (Heart)
 Blood moves through body by muscular contractions of heart.
- Blood vessels 血管
 Complex network of blood vessels carries materials to tissue and back to heart.
 Three main types of blood vessels: Arteries 动脉, Veins 静脉, Blood capillaries 微血管
- Valves
 Present in some blood vessels.
 Prevent backflow and ensure blood flows in one direction only.
 Human circulatory system is a double circulatory system. This means each complete circuit blood flow
through heart twice.
- Pulmonary circulation 肺循环: Transports blood between heart and lungs.
- Systemic circulation 人体循环: Transports blood between heart and all parts of body except lungs
 Advantage of double circulatory system: Increases pressure of blood and rate of flow, thereby speeding
up delivery of materials to tissues
Human blood circulatory system

2. 2
Structure of the human heart
 Heart is muscular organ with walls made of cardiac muscles 心肌.
 Coronary arteries 冠状动脉 supply nutrients and O2 to muscles and coronary veins removes wastes
from muscles.
 Heart is divided into 4 chambers. Two upper chambers are called auricles 心房 or atria (singular:
atrium) and two lower chambers are called ventricles 心室 (singular :ventricle)
 Septum 室间隔膜部 divides heart into right and left halves.
 Auricles have thinner walls than ventricles. When auricles contract, blood is pushed into ventricles.
 Left ventricle has thicker muscular wall than right ventricle. Right ventricle pump blood to lungs,
which lie next to heart. Left ventricle pump blood from heart to rest of body.
 Right atrium connects to right ventricle by tricuspid valve 三尖瓣. Left atrium connects to left ventricle
by bicuspid (mitral) valve 二尖瓣.
 Semilunar valves 半月瓣 are situated at entrances of aorta and pulmonary artery to prevent backflow of
blood into ventricles.
 Chordae tendineae 腱索 prevent valves from turning inside out when ventricles contract.
Function of human heart
 Heart is made up of 2 pumps located side by side.
 Right side of heart pumps deoxygenated blood 脱氧的血液 it receives from tissues to lungs. CO2 is
removed in lungs.
 Left side of heart pumps oxygenated blood 充氧的血液 it receives from lungs to rest of body. O2 is
removed in tissues for respiration.
Structure of human heart

3. 3
The blood vessels
 Arteries
- Blood vessels which carry blood from heart.
- Arteries deliver oxygenated blood, except pulmonary artery 肺动脉.
- Walls of arteries are thicker and stronger than veins because they have to withstand high
pressure of blood coming from heart.
 Veins
- Blood vessels which carry blood back to heart.
- Veins deliver deoxygenated blood, except pulmonary vein 肺静脉.
- Veins have thinner walls than arteries because blood pressure in veins is much lower than in
arteries.
- Since blood in veins may be moving against gravity, they contain valves to prevent blood from
flowing back.
 Capillaries
- Tiny blood vessels which connect arteries and veins. They have walls which are only one-cell
thick.
- O2 and nutrients move from blood through capillary walls into body cells. At the same time, CO2
and other waste products move from cells into blood.
Artery, blood capillary and vein
Exchange of materials in capillaries

4. 4
Characteristics Artery Vein Capillary
Cross section Circular Oval Circular
Size of wall Has thick muscular walls Has thin muscular walls One-cell thick
Valves
Absent (except in
pulmonary artery)
Present Absent
Lumen Narrow Fairly wide Very narrow
Blood colour Red Bluish-red Bluish-red
Oxygen content
Oxygenated blood (except
in pulmonary artery)
Deoxygenated blood
(except in pulmonary vein)
Oxygenated blood to
tissues; Deoxygenated
blood from tissues
Differences of artery, vein and capillary
The path of blood flow
 Vena cava 腔静脉 carries deoxygenated blood from various part of body to heart.
 From heart, pulmonary arteries carry deoxygenated blood to lungs. Gas exchange (respiration)
occurs in lungs.
 Oxygenated blood is returned to heart by pulmonary veins.
 Oxygenated blood leaves heart by aorta and is distributed by arteries to all parts of body (except
lungs). Gas exchange (respiration) occurs in tissues and organs.
 Veins carry deoxygenated blood from tissues and organs (except lungs) back to heart.
The role of the blood circulatory system in the transport of substances
 Blood circulatory system carries substances from one part of body to another.
Substances Example Transport from Transport to Transported in
Respiratory
gases
O2 Lungs Tissues Red blood cells
CO2 Tissues Lungs Plasma and red blood cells
Excretory
products
Urea Liver Kidneys Plasma
End products
of digestion
Glucose Small intestine Liver and tissues Plasma
Amino acids Small intestine Liver and tissues Plasma
Mineral salts
Calcium Small intestine Bones and teeth Plasma
Iron Small intestine and liver Bone marrow Plasma
Transport functions of blood

5. 5
Composition of human blood after centrifuged.
Maintaining a healthy heart
 Heart disease is a major cause of death in Malaysia.
 Factors that affect risk of getting heart disease:
- Heredity 遗传
Risk is increased if there is a family history of heart disease.
- Cholesterol and obesity
High cholesterol and obesity are major heart disease risk factors.
- Lack of exercise
Low levels of physical activity increase the risk of getting heart disease.
- Smoking
Smoking damages blood vessels and leads to heart disease and decreases amount of O2 that reaches
heart.
- Stress
People who are stressed are more prone to heart attacks.
- Alcohol
Excessive alcohol intake can elevate blood pressure, thus more likely causing heart disease.
 Ways to reduce the risk of getting heart disease:
- Avoid high cholesterol food. Eat more fruits and vegetables.
- Regular exercises help to keep body weight down, lower blood pressure and strengthen the heart.
- Lose weight to desirable weight range and keep within it with moderate eating and exercise.
- Relax and get enough sleep.
2.2 The Human Blood
The composition of blood
 Average human has 4-6dm3
of blood circulating in body.
 Major composition of blood can be separated by centrifugation 离心.
 Blood consists of a type of fluid called plasma 等离子体 which is made up of suspended blood cells
and blood fragments.
 Plasma makes up 55% of blood by volume. The other 45% consists of red blood cells 红血球, white
blood cells 白血球 and platelets 血小板.

6. 6
Plasma
 Yellow liquid in blood.
 90% of plasma is water. The rest are dissolved substances include:
- Nutrients such as glucose, amino acids and vitamins
- Proteins such as antibodies, hormones, enzymes, albumins and fibrinogen
- Inorganic ions such as sodium, calcium, chlorides and phosphates
 Main functions of plasma are:
- Transport nutrients to tissues.
- Remove waste products from tissues.
- Distribute hormones, enzymes, antibodies and other proteins.
- Distribute heat energy from liver and muscles to other parts of body.
Red blood cells (erythrocytes)
 Biconcave, disc-shaped cells without nucleus.
 Transport O2 from lungs to all parts of body.
 Contain red pigment called haemoglobin which combines with O2 molecules to form
oxyhaemoglobin.
 Carry CO2 from body cells to lungs.
 There are about 5 000 000 red blood cells in each mm3
of blood.
 Red blood cells are made in bone marrow 骨髓.
 Lifespan of red blood cell is about 120 days.
 When red blood cells are worn out, they are destroyed in liver and spleen 脾.
Composition of human blood
Whole red blood cell Section through red blood cell
Red blood cells

7. 7
White blood cells (leucocytes)
 Much larger than red blood cells and have nucleus.
 Usually irregular in shape, colourless and do not contain haemoglobin.
 Several type of white blood cells:
- Monocytes
- Lymphocytes
- Neutrophils
- Basophils
- Eosinophils
 Lifespan of white blood cells depends on type of white blood cells. It varies from a few hours to a few
months.
 Play a vital role in body defence against diseases. Some white blood cells produce antibodies to
render bacteria inactive white other white blood cells ingest bacteria.
 White blood cells can squeeze through walls of blood capillaries into spaces among cells to destroy
bacteria.
Platelets (thrombocytes)
 Cell fragments produced by large cells in bone marrow.
 Under a high-powered microscope, they appear as tiny oval-shaped structures without nucleus.
 There are between 250 000 and 500 000 platelets in every mm3
of blood.
 They play an important role in blood clotting 血液凝结. When blood vessel breaks, platelets release
clotting factors.
Blood groups
 There are many different systems by which blood is grouped but ABO system is best known.
 ABO system classifies human blood into main four groups called A, B, AB and O.
 During blood transfusion 输血, donor’s blood must be compatible with recipient’s blood.
 When an incompatible type of blood is transfused, red blood cells of donated blood will clump
together (agglutinate 粘合) and cause fatal 致命 blockages in recipient’s blood vessels.
Red blood cells, white blood cells and platelets

8. 8
Recipient’sblood
Donor’s blood
O A B AB
O ✔ ✘ ✘ ✘
A ✔ ✔ ✘ ✘
B ✔ ✘ ✔ ✘
AB ✔ ✔ ✔ ✔
Compatibility of blood groups in the ABO system
 Blood group O can safely donate blood, in small quantities. People with blood group O are called
universal donors 全适捐血者.
 Blood group AB can safely receive blood from anyone. People with blood group AB are called
universal recipients 全适受血者.
Group Can donate to Can receive from
A A and AB A and O
B B and AB B and O
AB AB All groups
O All groups O
Blood transfusion – donors and recipients
The importance of blood donation
 Blood may be needed for treatment of accident cases, cancer victims, haemophilia patient 血友病,
gastrointestinal bleeding 消化道出血, in surgery and childbirth where great loss of blood occurs.
 Donated blood cam be used either as unfiltered blood for one patient or separated into components to
help several patients.
Component Main uses
Plasma Great loss of blood in surgery and childbirth
Red blood cells Anaemia
Platelets Bone marrow failure, leukaemia
Blood proteins Burns
Main uses of the components of donated blood

9. 9
Storage and handling of donated blood
 Donor normally gives about 400cm3
of blood from a vein in arm.
 Blood should be collected under aseptic 无菌性 conditions into a sterilised 消毒 container containing
anticoagulant 抗凝 solution which prevents clotting.
 Donated blood is tested for ABO group and presence of antibodies that may cause problems in
recipient.
 Screening 筛查 tests are performed for evidence of donor infection with hepatitis, AIDS and other
sexually transmitted diseases 性传播疾病.
 Date of expiration should be written in label attached to blood container.
 Blood can be stored at 5 C for 10 days or longer if glucose is added.
 Blood may be separated into several components.
 Red blood cells can be stored under refrigeration for 42 days or can be frozen for up to 10 years.
 Platelets can be stored at room temperature for maximum 5 days.
 Frozen plasma can be kept up for up to one year.
 Frozen plasma and red blood cells should be thawed 解冻 in a water bath at temperature not
exceeding 38 C.
2.3 The Transport System in Plants
Wilting
 Non-woody plants depend on water stored in cells of stem for support.
 Wilting occurs in non-woody plants when water loss through aerial 空气 parts of plant exceeds
water absorption by roots.
 Cells in plants lose turgidity 膨胀度 (stiffness 刚性) and plant droops.
 Wilting can be important to plants because leaf surfaces are removed from direct rays of Sun and
stomata 气孔 closed. Water loss from plants will be reduced.
 Normally, a plant which has wilted will remain this condition until evening.
 During evening, water absorption exceeds water loss and cells become turgid.
Transpiration
 Transpiration is evaporation of water from aerial parts of plants.
 90% of water absorbed by roots is lost by evaporation from surfaces of cells in leaves and subsequent
diffusion of water vapour through stomata.
 9% is lost through cuticle 表皮.
 1% is used for photosynthesis.
Transpiration

10. 10
Stomata
 Stomata are pores 毛孔 in epidermis of leaves and stems.
 A pair of bean-shaped guard cells 保卫细胞 bound each stoma.
 In most dicotyledons 双子叶植物, stomata occur only in lower epidermis of leaf.
 In monocotyledons 单子叶植物, stomata are found in both sides of leaf.
 Most stomata open during day and close at night.
 The main function of stomata is to allow gases to diffuse in and out of leaf. During photosynthesis,
CO2 diffuses from atmosphere into leaf and O2 diffuses out from leaf into atmosphere.
 When stomata open, water vapour is released to surroundings through stomata by transpiration.
Stomata will close when transpiration exceeds water absorption.
Factor affecting the rate of transpiration
 Light intensity
Light stimulates opening of stomata and consequently increases transpiration.
 Temperature
Water molecules move faster in warm air, hence rate of transpiration is increased.
 Relative humidity 湿度
Rate of water loss depends on the difference in concentration of water molecules in leaf and atmosphere.
High relative humidity reduces water loss.
 Wind speed (Air movement)
Increase in wind speed increases rate of transpiration because movement of air carries away the
water vapour from stomata.
* Rate of transpiration can be measured by using potometer.
- Weight potometer measures weight lost by plant during a fix period of time.
- Bubble potometer measures the amount of water absorbed by plant during a fixed period of time.
Surface view and cross section of stoma
Weight potometer Bubble potometer

11. 11
Vascular tissues of a plant
 Vascular 血管 tissues are concerned with transport and are functionally equivalent to circulatory
system of mammals.
 2 types of vascular tissues:
- Xylem 木质部
- Phloem 韧皮部
 Xylem
- Main function: Transport water and mineral salts from roots to stem and leaves.
- Forms wood in shrubs 灌木 and trees. Therefore, xylem provides support to plants.
- Consists mainly of vessels, which are elongated 长 tubes with thick walls. Walls are strengthened
with substance called lignin 木质素. Xylem vessels are dead structures without protoplasmic 原生
质 contents and transverse 横 walls.
 Phloem
- Transport synthesized 综合 food substances from one part of plant to another.
- Consists mainly of sieve tubes 筛管. Sieve tubes are living walls without nucleus. Walls of sieve
tubes are composed largely of cellulose 纤维素. Transverse walls of sieve tubes are perforated 穿
孔 by pores and are call sieve plates 筛板.
- Each sieve tube cell has companion cell beside it.
The role of transpiration
 Helps transport water and dissolved minerals from roots of plant to leaves.
 Helps roots to absorb water. Water keeps cells turgid so that they can support the plant.
 Evaporation of water vapour from leaves keeps plant cool in hot weather.
 Removes excess water from plant.
Xylem vessels
Phloem cells