TRANSPORTATION IN LIVING THINGS-BIOLOGY FORM TWO

TOPIC FOUR

TRANSAPORT OF MATERIALS IN LIVING THINGS

The Concept of Transportation of Materials in Living Things

Unicellular organisms (for example amoeba), nutrients (for example oxygen and food) and waste products (for example carbon dioxide) can simply diffuse into or out of the cells from the surroundings. But in multi cellular organisms (for example humans and trees), many cells are very far away from the body surface, hence a transport system is required for the exchange of materials.

Organisms require transport systems so as to carry out various life processes. These life processes include nutrition, respiration, excretion, growth and development, movement,reproduction and coordination. For these life processes to take place, transport of materials is inevitable. Materials are transported either from environment into the organisms or from one part of an organism to another, and can also be transported from an organism into the environment.

For example, during nutrition organisms take in food substances that they need to produce energy, grow and carry out other life processes. These food substances must be taken in from the environment. The same case applies to reproduction which requires the movement of gametes(sex cells) from the sex organs to the area where fertilization occurs. Therefore, transport is very important for the survival and existence of living things.

The Importance of Transportation of Material in Living Things

Transport of materials is very important for the survival and development of living organisms. If transportation never existed, then no life on earth could be possible. The following is an outline of the importance of transport of materials in living things:

1.     It facilitates the removal of waste materials from the organism‟s body, the excess of which could harm an organism.

2.     It ensures that essential materials like oxygen, nutrients, water, hormones and mineral salts are supplied to the cells and tissues as required.

3.     It enables essential substances to move from one part of the body to another. For example, food manufactured by photosynthesis in plant leaves is transported from leaves to other organs of the plant for use or storage.

Diffusion, Osmosis and Mass- flow

The Meaning of Osmosis, Diffusion and Mass- Flow

Explain the meaning of osmosis, diffusion and mass- flow

View Teacher Notes

Life processes in organisms take place at the cell level. Therefore, it is necessary for substances to move in and out of the cells. There are two ways through which substances can move across the membrane. Materials in living organisms move by diffusion, osmosis and mass flow.

Diffusion

This is the movement of materials from a region of higher concentration to a region of lower concentration until equilibrium of two sides is maintained. Diffusion can also be defined as the movement of ions or molecules from the region of higher concentration to the region of lower concentration, without involving any permeable membrane. A difference in concentration of a substance between two regions is known as concentration gradient.

Diagram showing diffusion

Materials are transported in the body system of living things from the area where they are abundant to areas where they are less abundant, and this process or mechanism of transportation in these animals is termed as diffusion. Diffusion occurs in exchange of gases like oxygen or carbon dioxide during respiration in animals and plants. Also, diffusion takes place during distribution of nutrients and digested foods in living organisms.

Osmosis

This is the movement of water molecules from a region of higher concentration to a region of lower concentration through a semi-permeable membrane. A partially-permeable membrane is a membrane that allows small particles such as water molecules to pass through it, but not larger particles such as sugar molecules and ions from salts. Examples of semi-permeable membranes are cell membranes and a pig‟s bladder. These membranes allow transportation of water through them. In spite of the fact that they allow transportation of water through them, they do not permit the passage of sugar or salt molecules because they are solutes. Osmosis occurs when water moves down its concentration gradient across the semi-permeable membrane.

Therefore, for osmosis to take place there must be:

1.     two solutions with different concentrations; and

2.     a partially permeable membrane to separate them.

A dilute solution has a high water concentration, while a concentrated solution has a low water concentration. For example, when salt is dissolved in water:

1.     A little dissolved salt produces a dilute solution with a high water concentration

2.     A lot of dissolved salt produces a concentrated solution with a low water concentration. Diagram of osmosis

Mass flow

Diffusion and osmosis occurs very slowly and cover short distances. In animals and plants, materials are usually transported a long distance and in large quantities. For example, food nutrients from the small intestine have to be moved to cells in the extremities such as toes and fingers, where the nutrient materials have to be transported a long distance. Therefore, an efficient and fast mechanism is required to facilitate this movement. That is when mass flow comes in.

Mass flow is the movement of materials in large quantities and across a long distance in the body of an organism due to differences in pressure between the two regions. Materials in higher plants and animals are moved by the process of mass flow. For example, the manufactured food in plant leaves has to be moved to all plant parts, for use or storage, by mass flow.

Experiments to Demonstrate the Process of Diffusion, Osmosis and Mass Flow

Carryout experiments to demonstrate the process of diffusion, osmosis and mass flow

Demonstration of the process of diffusion

Take a bottle of perfume and move to one corner of the classroom. Open a bottle and observe what happens. The result is, after a few seconds, the whole classroom is filled with a smell of the perfume. This means that the molecules of the perfume moves from the region of higher concentration (the bottle) to a region of lower concentration (air). That is why the smell is felt by a person standing several meters away from the source of the perfume.

Some important processes that involve diffusion are:

1.     Gaseous exchange in the lungs of animals and in the leaves of plants

2.     Absorption of digested food in the ileum the process of diffusion

3.     Removal of west materials from cells

4.     Absorption of nutrients and oxygen into cells

Demonstration of the process of osmosis

Procedure

Peel a potato and cut it as shown in the diagram below. Then fill the depression with brine(concentrated solution of sodium chloride). Leave the set up until the next day and observe what happens to the level of brine in the potato.

Result

Diffusion

It is the movement of all types of substances from the area of their higher concentration to the area of their lower concentration

Diffusion can operate in any medium

Diffusion is applicable to all types of substances (soilds, liquids and gases)

It does not require any semi-permeable membrane

It is purely dependent upon the free energy of the diffusing substance

It helps in equalizing the concentration of the diffusing substance throughout the available space

Osmosis

It is the movement of only solvent or water from the area of their higher concentration to the area of their lower concentration through a partially permeable membrane

Osmosis operates only in a liquid medium

It is applicable only to solvent part of a solution

A semi-permeable membrane is a must for operation of osmosis

Osmosis is dependent upon the degree of reduction of free energy of one solvent over that of another

It does not equalize the concentration of solvent on the two sides of the system

Turgor  pressure  or  hydrostatic  pressure  does  not

normally operate in diffusion	Osmosis is opposed by turgor or hydrostatic pressure of system
It is not influenced by solute potential	Osmosis is dependent upon the solute potential

Diffusion of a substance is mostly dependent of the             It  is  dependent  upon  the  number  of  particles  of  other  substances

presence of other substances

Factors like water potential, solute potential and pressure potential do not affect diffusion

dissolved in a liquid

Factors like water potential, solute potential and pressure potential affect osmosis in a living system

In the following day, you will find that the level of brine will have risen as shown. This means that water has moved from the potato to the brine solution causing the brine level to rise up. The water has moved from a region of high water concentration (the potato) through the cell membranes of the potato cells (partially permeable membrane) to the region of low water concentration (the brine).

The Differences between Diffusion, Osmosis and Mass Flow

Outline the differences between diffusion, osmosis and mass flow

Differences between diffusion and osmosis

The Roles of Diffusion, Osmosis and Mass Flow in Movement of Materials in Living Organisms

Explain the roles of diffusion, osmosis and mass flow in movement of materials in living organisms

Materials are transported in the body system of living things from the area where they are abundant to areas where they are less abundant, and this process or mechanism of transportation in these animals is termed as diffusion. Diffusion occurs in exchange of gases like oxygen or carbon dioxide during respiration in animals and plants. Also, diffusion takes place during distribution of nutrients and digested foods in living organisms.

1.     Through the process of osmosis, nutrients get transported to cells and waste materials get moved out of them.

2.     The pressure within and outside each cell is maintained by osmosis as this process ensures a balance of fluid volume on both sides of the cell wall. If fluid volume within a cell is more than the fluid volume outside it, such pressure could lead the cell to become turgid and explode. On the contrary, if fluid volume outside the cell is more than the fluid volume within, such pressure could lead the cell to cave in. Both cases would be detrimental to normal and healthy cellular function.

3.     It is via osmosis only that roots of plants are able to absorb moisture from the soil and transport it upwards, towards the leaves to carry out photosynthesis. Plants wouldn't exist without osmosis; and without plants, no other life could exist as they are a vital link of the entire food chain of the planet.

4.     Without osmosis, it would be impossible for our bodies to separate and expel toxic wastes and keep the bloodstream free from impurities. The process of blood purification is carried out by the kidneys which isolate the impurities in the form of urine.

5.     Therefore, the role of osmosis is to fold: it helps maintain a stable internal environment in a living organism by keeping the pressure of intercellular and intracellular fluids balanced. It also allows the absorption of nutrients and expulsion of waste from various bodily organs on the cellular level. These are two of the most essential functions that a living organism cannot do without.

Transport of Materials in Mammals, the Structure of the Mammalian Heart

The External and Internal Structures of the Mammalian Heart

Describe the external and internal structures of the mammalian heart

TRANSPORT OF MATERIALS IN MAMMALS

Mammals are the complex multicellular organisms whose bodies are made up of numerous cells and tissues. In this case, diffusion alone is not enough to insure efficient carrying out of life process. Therefore mammals have an elaborate transport system that is made up of the heart ,blood and blood vessel.

The structure of the mammalian heart

The heart is a muscular organ about the size of a closed fist that functions as the body‟s circulatory pump. It takes in deoxygenated blood through the veins and delivers it to the lungs for oxygenation before pumping it into the various arteries. The heart is located in the thoracic cavity between the two lungs.

The external structure of the mammalian heart is as shown in the labelled diagram below:

The mammalian heart is broader at the top and narrower at the bottom. It is enclosed by a double layer of tough and elastic membranes called pericardium. These membranes prevent the heart from ever-expanding when beating very fast. Also the pericardium secretes a fluid which enables the membranes to move smoothly against each other.

The walls of the ventricles are thicker than those of the auricles because the ventricles pump blood a greater distance than the auricles. Auricles pump blood to the ventricles while the ventricles pump blood to the other parts of the body.

The left ventricle is thicker than the right ventricle because the right ventricle pumps blood to the lungs while the left ventricle pumps blood to the rest of the body parts.The heart consists of four

chambers, right and left atria and right and left ventricles. The functions of each part and the associated structures are as follows:

1.     The right atrium links to the right ventricle by the tricuspid valve. This valve prevents back flow of the blood into the atrium above, when the ventricle contracts.

2.     The left atrium links to the left ventricle by the bicuspid valve. This valve also prevents back flow of the blood into the atrium above, when the ventricle contracts.

3.     Semi-lunar (pocket) valves are found in the blood vessels leaving the heart (pulmonary artery and aorta). They only allow exit of blood from the heart through these vessels following ventricular contractions.

4.     Ventricles have thicker muscular walls than atria. When each atrium contracts, it only needs to propel the blood a short distance into each ventricle while ventricles pump blood to distant body parts.

5.     The left ventricle has even thicker muscular walls than the right ventricle. The left ventricle needs a more powerful contraction to propel blood to the systemic circulation (all of the body apart from the lungs). The right ventricle propels blood to the nearby lungs. So, the contraction does not need to be so powerful.

INTERNAL STRUCTURE OF THE MAMMALIAN HEART

The heart has several valves. And these valves have flaps that ensure that blood flows in one direction only.

These valves include the following:

1.     The tricuspid valve; found between the right auricle and right ventricle

2.     The bicuspid valve: found between left auricle and left ventricle

3.     Semi-lunar valves which are located at the bases of the pulmonary artery and aorta to prevent blood from flowing back into the ventricles.

These valves will close if the blood flows back. The valves are held in place by tendons which prevent the flaps from turning inside out.The right and left sides of the heart are separated by septum which is a thick muscular wall which prevents mixing of oxygenated and deoxygenated blood.

The Functions of the External and Internal Parts of the Mammalian Heart

Explain the functions of the external and internal parts of the mammalian heart

Functions of parts of the mammalian heart
Part of the heart		Function
Aorta		The largest artery in the body; it conducts freshly oxygenated blood from the heart to the tissues.
Superior	vena	Large vein that brings deoxygenated blood from the upper parts of the body to the right atrium
cava
Inferior vena cava		Large vein that brings deoxygenated blood from lower regions of the body to right atrium
Pulmonary artery		Carries deoxygenated blood from the right ventricle to the lungs
Pulmonary vein		Blood vessel that carries oxygenated blood from the lungs to the left atrium
Right atrium		This chamber of the heart receives deoxygenated blood from the body (from the superior and inferior ven
		cava).
Left atrium		This chamber of the heart receives oxygenated blood from the lungs
Tricuspid valve		Located on the right side of the heart between the right atrium (RA)and right ventricle (RV)
Bicuspid valve		Located on the left side of the heart between the left atrium (LA) and the left ventricle (LV)
Right ventricle		The chamber of the heart that pumps deoxygenated blood to the lungs
Left ventricle		Receives blood from the left atrium and pumps it into the aorta for transport to the body cells
Septum		Divides the right and left chambers of the heart

The Adaptations of the Parts of the Mammalian Heart to their Functions

Explain the adaptations of the parts of the mammalian heart to their functions

The heart is adapted to carry out its functions by having the following features:

1.   The cardiac muscle is adapted to be highly resistant to fatigue.

2.     The heart has a large number of mitochondria enabling continuous supply of energy to the heart and numerous myoglobins (oxygen storing pigment).

3.     The presence of the cardiac muscles enables the heart to beat rhythmically.

4.     The pericardium which surrounds and protects the heart from physical damage.

5.     Pericardial fluid which prevents friction when the heart beats.

6.     The outer layer of the pericardium attaches to the breastbone and other structures in the chest cavity and thus helps to hold the heart in place.

7.     Bicuspid and tricuspid valves between atria and ventricles which prevent the backflow of blood.

8.     Septum which prevents the mixing of deoxygenated blood in the right and oxygenated blood in the left chambers of the heart.

9.     Its own blood supply for supplying nutrients and removing waste.

10.  The left ventricle has thick muscular wall to pump blood at a higher pressure to the distant body tissues,

11.  The heart is supplied with the nerves which control the rate of heartbeat depending on the body requirements.

Blood vessels

Blood vessels are intricate networks of hollow tubes that transport blood throughout the entire body. This is an essential function as blood delivers valuable nutrients to and removes wastes from our cells. Blood vessels are constructed of layers of connective tissue and muscle. The inner blood vessel layer is formed of endothelium. In capillaries and sinusoids, endothelium comprises the majority of the vessel. There are three types of blood vessels namely arteries,veins and capillaries. Each of these vessels has a different structure and function.

The Structure of Arteries, Veins and Capillaries

Describe the structure of arteries, veins and capillaries

Basic structure

·        Capillaries consist of anendothelium whichis only one cell thick.

·        Walls of arteries and veins consist of 3 layers.

·        The inner layer consists of a thin layer of endothelial cells.

·        The middle layer is made up of smooth muscle with some elastic fibres. This layer controls the diameter of the vessel and hence the amount of blood and its rate of flow.

·        The outer layer is composed of connective tissue; this holds the blood vessels in place in the body.

Detailed structure

Arteries

·        The walls of arteries are much thicker as it carries blood away from the heart at high pressure.

·        Major arteries close to the heart also have thick layers of smooth muscle in their walls to withstand the increases in pressure as the heart pumps.

·        The walls also have a large proportion of elastic fibres in both the inner and middle layers – this allows for the arteries to stretch according to the increases in volume of blood. As the heart relaxes the artery walls return to their original position, hence pushing the blood along – maintaining a constant flow in one direction.

·        Arteries are near the surface of the skin; the changes in the arteries diameter can be felt as a pulse.

Veins

·        The walls of veins are thinner than the walls of arteries, as the blood they receive from the capillaries is at a much lower pressure.

·        The walls have fewer elastic fibres and the lumen is wider (to allow for easier blood flow).

·        Veins have two mechanisms for keeping the blood flow constant and in one direction. Firstly, many veins are close to muscles, hence when the muscles contract they compress the walls of the vein – pumping blood forwards. Veins also have valves which are spaced along regular intervals in veins. They work much like one-way swinging doors – as the blood is forced through the

valve opens. However, once the pressure drops and the blood flow decreases, the valve shuts – preventing back flow of blood.

Capillaries

·        They are extremely, tiny microscopic vessels that bring blood into close contact with the tissues, for the exchange of chemical substances between cells and the bloodstream.

·        The one cell thick endothelial layer is a continuation of the lumen arteries and veins.

·        Diffusion is a relatively slow process and hence the structure of capillaries is suited to slowing down the flow of blood.

·        In order to maximize the exchange of substances between the blood and cells, capillaries have thin walls (for more efficient diffusion) a small lumen (that forces blood cells to pass through in single file, slowing down the rate of flow and maximizing their exposed surface area).

·        They form an expansive blood flow network, such that no cells are far from blood supply

		How different blood vessels are adapted for their function
		Blood	Function	Adaptation
		vessel
		Artery	Carries  blood  away  from  heart  at  high	Thick, elastic, muscular walls to withstand pressure and		to
			pressure	exert force (pulse)
		Vein	Returns low-pressure blood to heart	Large  diameter  to  offer  least  flow  resistance.  Valves		to
				prevent back flow.
		Capillary	Allows exchange of materials between blood	Thin, permeable walls
			and tissues

Arteries	Veins	Capillaries
All  arteries	carry  blood away from  the	Capillaries	carry
		blood from arteries to the
heart	All veins carry blood towards the heart

veins

With the exception of the pulmonary artery, all arteries carry oxygenated blood

They carry blood which is usually rich in digested food materials

With the exception of the pulmonary vein, all         Blood slowly      loses       its

veins carry deoxygenated blood                                oxygen

Except for the hepatic portal vein, they carry

blood     which     usually     has little digested       Blood slowly loses its food

food materials

Have	relatively	narrower  lumens  (see	Have  relatively	wide  lumens  (see  diagrams	Have	relatively		narrow
					lumens	(see		diagrams
diagrams above)			above)
					above)
Have	relatively	a thick layer  of  muscles	Have  relatively	a thin layer  of  muscles  and	They do  not		have muscles
and elastic fibres			elastic fibres		and elastic fibres
They have thick outer walls			They have thin outer walls		Walls	are	only one  cell
					thick
					Pressure gradually falls as
They carry blood at high pressure			They carry blood at low pressure		blood flows from arteries to
					veins
Do not have valves (except for the semi-			Have valves throughout the main veins of the
lunar valves of the pulmonary artery and					Have no valves

body to prevent the back flow of blood.

the aorta)

Have bright red blood (because it is rich in	Brown-red blood	Brown-red blood
oxygen)
Located deep in the to body surface	Located near to body surface	Capillaries are found inside
		all tissues
Walls are not permeable	Walls are not permeable	Walls are permeable
Blood flows in pulses	No pulse	Pulse gradually disappears

Cross section of vein

Differences between arteries, veins and capillaries

The Blood

The Major Components of the Blood

List the major components of the blood

Blood is the red fluid that circulates in our blood vessels. The average human body containsabout 4 to 5 litres of blood. Blood is classified as a connective tissue and consists of two maincomponents:

1.     Plasma which is a clear extracellular fluid.

2.     The solid component, which are made up of the blood cells and platelets

The solid component is made up of blood cells except for the platelets, which are tiny fragmentsof bone marrow cells.

The solid component consists of blood cells (corpuscles) which include:

1.     Erythrocytes, also known as red blood cells (RBCs)

2.     Leukocytes, also known as white blood cells (WBCs)

3.     Platelets, also known as thrombocytes

Red blood cells, most white blood cells, and platelets are produced in the bone marrow, the soft fatty tissue inside bone cavities. The white blood cells (lymphocytes) are also produced in the lymph nodes and spleen, and in the thymus gland.

Within the bone marrow, all blood cells originate from a single type of unspecialized cell calleda stem cell. When a stem cell divides, it first becomes an immature red blood cell, white bloodcell, or platelet-producing cell. The immature cell then divides, matures further, and ultimatelybecomes a mature red blood cell, white blood cell, or platelet.

Blood cells

By volume, the plasma constitutes about 55% of whole blood, and red blood cells, platelets and white blood cells about 45%.

The Function of Major Blood Components

Explain the function of major blood components

Red blood cells

Red blood cells (RBCs) have two main functions:

1.     To pick up oxygen from the lungs and deliver it to tissues elsewhere.

2.     To pick up carbon dioxide from other tissues and unload it in the lungs.

Erythrocytes transport oxygen in the blood through the red pigment called haemoglobin.Haemoglobin contains iron and proteins joined to greatly increase the oxygen carrying capacity of erythrocytes. The high surface area to volume ratio of erythrocytes allows oxygen to be easily transferred into the cells in the lungs and out of the cells in the capillaries of the systemic tissues.Erythrocytes are produced inside red bone marrow from stem cells at the astonishing rate of about 2 million cells every second.

White blood cells

Although the white blood cells accounts for only about 1% of the blood, they play a very important role in the body. Their main function is to protect the body against disease

pathogens.There are two of white blood cells, each of which plays a specific role in protection of the body against illness and disease.

1.     Phagocytes: Engulf and digest invading bacteria and viruses (pathogens). It is the body‟s main defence against germs (microbes).

2.     Lymphocytes: produce antibodies which neutralize antigens from bacteria or viruses. They kill microbes or make them clump together, to be removed in the lymph glands.

White blood cells are produced in the yellow marrow of the bone, spleen, thymus and lymphatic system.

Platelets

Platelets are small fragments of bone marrow cells and are therefore not really classified as cells themselves. Platelets have the following functions:

1.     Secrete vasoconstrictors which constrict blood vessels, causing vascular spasms in broken blood vessels.

2.     Form temporary platelet plugs to stop bleeding.

3.     Secrete procoagulants (clotting factors) to promote blood clotting.

4.     Dissolve blood clots when they are no longer needed.

5.     Digest and destroy bacteria.

6.     Secrete chemicals that attract neutrophils and monocytes to sites of inflammation.

7.     Secrete growth factors to maintain the linings of blood vessels.

In general, the blood platelets functions in healing of the wounds when the skin gets broken. This is achieved by clumping together of the platelets to form a network of mesh, hence bleeding is stopped.

Plasma

Plasma is the non-cellular or liquid portion of the blood. Plasma is a mixture of water, proteins, and dissolved substances. Around 90% of plasma is made of water, although the exact

percentage varies depending upon the hydration levels of the individual. Blood plasma has the following functions:

1.     Plasma serves as a transport medium for delivering nutrients to the cells of the various organs of the body.

2.     It transports waste products derived from cellular metabolism to the kidneys, liver, and lungs for excretion.

3.     It fights infections since it contains antibodies.

4.     It is also a transport system for blood cells, and it plays a critical role in maintaining normal blood pressure.

5.     Plasma helps to distribute heat throughout the body and to maintain homeostasis, or biological stability, including acid-base balance in the blood and body

6.     It carries and transports some hormones.

Blood Groups and Blood Transfusion

The Concepts of Blood Group and Blood Transfusion

Explain the concepts of blood group and blood transfusion

Human blood can be grouped into four blood groups namely groups A, B, AB and O. They were discovered in 1900 and 1901 at the University of Vienna by Karl Landsteiner in the process of trying to learn why blood transfusions sometimes cause death and at other times save a patient.This classification is based on the type of antigens in the red blood cells and antibodies in the plasma.

Red blood cells have proteins (antigens) on their surface: A, B or A and B. Plasma hasantibodies

which can cause agglutination: anti-A and anti-B.

Serum is blood plasma without fibrinogen. It can be stored without clotting, and is used in transfusions.

Blood group                          Antigen                     Antibodies                                                Agglutinates

A	A	Anti-B	Anti-A serum
B	B	Anti-A	Anti-B serum
AB	A and B	None	Anti-A and anti-B serums
O	None	Anti-A and anti-B	Neither serum

Consider the table above. People with type A blood will have the A antigen on the surface of their red cells (as shown in the table). As a result, anti-A antibodies will not be produced by them because they would cause the destruction of their own blood. However, if B type blood is injected into their systems, anti-B antibodies in their plasma will recognize it as alien and burst or agglutinate the introduced red cells in order to cleanse the blood of alien protein.

Individuals with type O blood do not produce any antigens. Therefore, their blood normally willnot be rejected when it is given to others with different blood types. As a result, type O peopleare universal donors for transfusions, but they can receive only type O blood themselves. Thosewho have type AB blood do not make any antibodies. Their blood does not discriminate againstany other blood type. Consequently, they are universal receivers for transfusions, but their bloodwill be agglutinated when given to people with every other type because they produce both kindsof antigens.

Blood grouping

It is easy and inexpensive to determine an individual's blood type from a few drops of blood.This is how blood typing/grouping it is done: A serum containing anti-A antibodies is mixed with some of the blood. Another serum with anti-B antibodies is mixed with the remaining sample. Whether or not agglutination occurs in either sample indicates the blood type. For instance, if an individual's blood sample is agglutinated by the anti-A antibody, but not the anti-B antibody, it means that the A antigen is present but not the B antigen. Therefore, the blood type is A.

Rhesus factor

Some people have another antigen called Rhesus antigen on their red blood cells while others do not have it. Those having this antigen are referred to as Rhesus positive (Rh+) and those without

are it are Rhesus negative (Rh-). Rh antigen occurs in red blood cells and Rh antibody occurs in blood plasma.

If Rh antibody mixes with Rh antigen during blood transfusion, agglutination will occur. Rh+ can stimulate the Rh- to produce antibodies to act against Rh+ antigens. However, the Rh-cannot stimulate the Rh+ blood to produce antibodies against Rh-. Therefore, an Rh+ person can receive blood from the Rh- donor. The donated blood below is group AB rhesus positive (AB+).

The Relationship between Blood Groups and Blood Transfusion

Outline the relationship between blood groups and blood transfusion

Blood transfusion

Blood transfusion is the transfer of blood from one person (donor) to another person (recipient)through blood vessels. Transfusion is done to replace lost blood due to illness, accidents or bleeding. The donor is the person who gives blood while the recipient is the person who receives blood.

When performing blood transfusions it is important to avoid combining corresponding antigens and antibodies because they cause agglutination of red blood cells which may lead to death of the recipient. Agglutination is the clumping of red blood cells. Blood transfusion is only possible if blood groups are compatible. Blood group compatibilities are as shown in the table below.

Recipient	Donor
	A	B	AB	O
A	√	×	×	√
B	×	√	×	√
AB	√	√	√	√
O	×	×	×	√

Note: a tick (√) means compatible and a cross (×) means incompatible.

Individuals with blood group AB can receive blood from individuals of all blood groups and are known as universal recipients. Individuals with blood group O can donate blood to individuals of all blood groups and are known as universal donors.

The Advantages and Disadvantages for Blood Transfusion

Explain the advantages and disadvantages for blood transfusion

Advantages of blood transfusions

Blood transfusion does so much for patients in need. The gift of life is donated, tested, processed and sent to hospitals‟ transfusion service departments where more important work is done to ensure it is compatible with the recipient.

Blood transfusion has a number of advantages. These are some of the benefits the donated bloodcan provide for patients in need:

1.     Increase low haemoglobin levels: low haemoglobin can cause damage to body organs and tissues due to low oxygen levels. Donated blood, with sufficient haemoglobin, can correct the problem of low haemoglobin level of the recipient.

2.     Help stop bleeding: bleeding may not be controlled if platelets and/or clotting factors are low. Receiving blood with high clotting factors can solve the problem.

3.     Keeps the heart pumping: low blood volume can lead to low pressure and the heart may not be able maintain the circulation of blood.

4.     Help with serious blood infections when other methods fail. For example, blood transfusion may serve as a treatment method for people with sickle cell anaemia or blood cancer(leukaemia).

5.     Provide red cells and platelets when the bone marrow is compromised as with blood cancers, bone marrow transplants, chemotherapy, etc.

6.     Provide red cells and platelets for patients with blood disorders such as sickle cell.

7.     Save someone‟s life: people who have had a big loss of blood due to a number of reasons can have their lives saved once they receive donated blood.

8.     Because blood transfusion involves screening of the donor‟s blood, if the donor has any health problem it can be detected and hence treated before getting worse.

Disadvantages of blood transfusions

Although blood transfusions can be life-saving, they are not without risks. The following are disadvantages of blood transfusions:

Medical reactions:

1.     Allergic reaction: This is the most common reaction. It happens during the transfusionwhen the body reacts to plasma proteins or other substances in the donated blood.

2.     Fever reaction: The person gets a sudden fever during or within 24 hours of thetransfusion. Headache, nausea, chills, or a general feeling of discomfort may come withthe fever.

3.     Haemolytic reactions: In very rare cases, the patient's blood destroys the donor red bloodcells. This is called haemolysis. This can be severe and may result in bleeding and inkidney failure.

Diseases: If proper screening of the donated blood is not observed, it can cause transmission of diseases from the donor to the recipient. Examples of such transmissible diseases are HIV virus, hepatitis, and other infections.

Patients who are given too much blood can develop high blood pressure, a concern forpeople who have heart disease.

Precautions to be Taken During Blood Transfusion

Outline precautions to be taken during blood transfusion

Blood transfusion precautions

Certain precautions and guidelines must be adhered to in blood transfusion to ensure the safety of the procedure. The precautions may include the following:

1.     Donated blood must carefully and thoroughly be screened for any infectious diseases before being transfused to the recipient. The blood should be screened for diseases like hepatitis B, HIV virus, and all sexually transmitted diseases (STDs).

2.     The donated blood must be matched with the recipient's blood type, as incompatible blood types can cause a serious adverse reaction (transfusion reaction). Blood is introduced slowly by gravity flow directly into the veins (intravenous infusion) so that medical personnel can observe the patient for signs of adverse reactions.

3.     During blood transfusion, vital signs such as body temperature, heart rate, and blood pressure are carefully monitored.

4.     Some patients may get a sudden fever during or within 24 hours of the transfusion, which may be relieved with pain-relieving drugs such as panadol, diclofenac or paracetamol.This fever is a common reaction to the white blood cells present in donated blood.

Blood Circulation

Blood Circulation in Humans

Describe blood circulation in humans

Blood circulation is the flow of blood from the heart to all body parts and back to the heart.Blood circulation or circulatory system, also called cardiovascular system, is one of three mainsystems in human body which consist of organs and tissues.

The cardiovascular systems of humans are closed, so the blood never leaves the network of bloodvessels. But oxygen and nutrients diffuse across blood vessel layers and enter interstitial fluid,which carries it to the target cells and carbon dioxide and wastes in the opposite direction.

The human blood circulation consists of two circulations namely the pulmonary circulation andsystemic circulation.

Pulmonary circulation

Pulmonary circulation is the movement of blood from the heart, to the lungs, and back to theheart again. This is just one phase of the overall circulatory system. In this type of circulation,the blood flows from the right ventricle to the lungs and from the lungs to the left auricle. In thepulmonary circulation, the blood circulates to and from the lungs, to release the carbon dioxideand pick up new oxygen.

In the pulmonary circulation, blood from all body parts (except the lungs) enters the right auriclethrough vena cava. From the right auricle the blood descends into the right ventricle through thetricuspid valve. When the ventricle contracts, the blood is pushed into the pulmonary artery thatbranches into two main parts: one going to the left lung, and another to the right lung. The fresh,oxygenated blood returns to the left auricle of the heart through the pulmonary vein.

Systemic circulation

Systemic circulation is the flow of blood between the heart and the body parts. In this particularcirculation, the blood flows from the left ventricle to different parts of the body and from22different parts of the body to the right auricle. The systemic circulation supplies nourishment toall of the tissues located throughout your body, with the exception of the heart and lungs becausethey have their own systems. Systemic circulation is a major part of the overall circulatorysystem. In this circulation, the blood circulates into the body‟s systems, bringing oxygen to all itsorgans, structures and tissues and collecting carbon dioxide waste.

The systemic cycle begins when the oxygenated blood coming from the lungs enters the leftauricle. As the chamber fills, it presses open the bicuspid valve and the blood flows down intothe left ventricle. When the ventricles contract during a heartbeat, the blood on the left side isforced into the aorta. This largest artery of the body is an inch wide. The blood leaving the aortabrings oxygen to all the body‟s cells through the network of ever smaller arteries and capillaries.The used blood from the body returns to the heart through the network of veins. All of the bloodfrom the body is eventually collected into the two largest veins: the superior vena cava, whichreceives blood from the upper body, and the inferior vena cava, which receives blood from thelower body region. Both venae cavae empty the blood into the right auricle of the heart.

The process by which blood passes through the heart twice before it returns to the other parts ofthe body is called double circulation.

The Importance of Blood Circulation in Humans

Explain the importance of blood circulation in humans

Importance of blood circulation

Blood circulation is essential for a healthy body. Blood circulation is important because itfacilitates the following processes to take place in the body:

1.     Every cell in the body needs to received oxygen and nutrients. Blood rich in oxygen is sent tothe body organs, tissues and cells to nourish them through blood circulation.

2.     It enables transportation of waste products from body tissues to excretory organs so as to beremoved from the body.

3.     Protects the body against diseases and infections through the white blood cells.

4.     Facilitates blood clotting to prevent loss of blood.

5.     Maintains body temperature by distributing body heat evenly from the liver and spleen to allbody parts.

Disorders and Diseases of the Human Blood Circulatory System

Mention disorders and diseases of the human blood circulatory system

Additional notes on diseases and disorders of the circulatory system:

Hypertension

High blood pressure (hypertension) is defined as high pressure (tension) in the arteries, which arethe vessels that carry blood from the heart to the rest of the body.

Disease / Disorder                              Description                                 Causes                                                               Effects / Symptoms

Haemorrhagic

anaemia

- due to loss of blood

Iron-deficiency anaemia

-  due

to

insufficient

iron,

often

due

tdietary

deficiency.

Haemolytic

anaemia

result

from

the

increased destruction of

red blood

cells

e.g.due

A reduction in the quantity

to

toxic

chemicals,

of(oxygen

carrying)

autoimmunity,

the

1

Anaemia

haemoglobin in the blood

action

of    parasites,

and/or

below

normal

abnormal

forms

of

quantity of red blood cells.

haemoglobin

or

abnormal

red

blood

cells.

Anaemia

can

also

be

caused by the impaired

production of red blood

cells,

as

in

leukaemia(when

red

blood cell production in

the

bone

marrow

is

suppressed).

Narrowed

coronary

arteries being unable to

supply

increased  blood

flow

required

for

2

Angina

Pain afterphysical effort

increased

physical

exertion.

(The

arteries

may

have

been

narrowed

by

the

accumulation

of

Excessive tiredness

Breathless nesson exertion

Pallor (i.e.looking pale, esp. on face and palms)

Low resistance to infection

Typical           symptoms

include short-term discomfort such as an ache, pain or tightness across the front of the

chest when or immediately following

exertion or other situations in which

Balloon-like     bulge      or

Aneurysm                                            swelling in the wall of a nartery

Hardening         of          the

arteries.(Arteriolosclerosis

is     the      hardening      of

arterioles.)Artery       walls

thicken, stiffen  and  lose

3                                Arteriosclerosis                                   elasticity,   a    progressive

condition   that    typically

worsens  overtime  unless

action is taken to address

it.Note:  Healthy  arteries

are flexible and elastic.

atheromatousplaque         -

see atherosclerosis, below.)

In general, causes can be genetic or due to

disease, e.g.1. a degenerative disease a syphilitic infection - causing damage to the muscular coat of the

blood vessel2.a congenital deficiency in the muscular wall

High     blood    pressure

(also known as hypertension) is widely cited as a cause of, or at least a contributory

factor           to,           the

development of arteriosclerosis.To reduce risk, keep blood

pressure within a healthy range. See also how to reduce risk of atherosclerosis (below).

heart rate is increased e.g. due to panic or an

argument.Other less common effects & symptoms are also possible e.g. similar pain when or soon after eating.

Aneurysms can cause the wall of the blood vessel to weaken. When an aneurysm gets bigger the risk of rupture increases. That can lead

to severe haemorrhage(bleeding) and other complications

- some of which may be life threatening.

Arteriosclerosis         (in

combination            with

atherosclerosis or otherwise) can reduce the flow of blood, hence the supply of oxygen, nutrients etc.,to tissues

in the affected area.Arteriosclerosis can affect any artery in the body but is of greatest concern when occurs in the heart (coronary arteries) or

the brain.

A  chronic  disease

that

can

remain

asymptomatic

for

decades.

However,

blood flow is restricted

and

eventually

obstructed.Various

complications

of

advanced

•Multiple

atherosclerosis

are

fatty

One

of

the

plaques(consisting

possible.

of

e.g.cholesterol

most significant risks is

and

of an infarction due to

triglyceride)accumulate

plaque

suddenly

on  the

inner  walls

soft

of

causing

the

arteries.To

rupturing,

reduce

of

a

Atherosclerosis  (Atheroma)-  a

formation

4

risk:1. Eat sensibly (see

clot)

commontype  ofarteriosclerosis

thrombus(blood

balanced

diet)2.Don't

can

slow

or

stop

(see above)

that

smoke3.

Take

to

appropriate

blood  flow  leading

regular

exercise4.

Maintain

death of the tissues fed

a

the

healthy

body

by

weight5.

of  a

Do

not

artery.Thrombosis

consume

artery

can

excessive alcohol

coronary

cause

a

heart

attack(Myocardial

infarction).The

same

process in an artery to

the

brain

is  commonly

called

stroke.6.

Coronary

thrombosisA

thrombus

is

a

blood

clot.Thrombosis

is

a

condition

in

which