EXAMPLES OF MATERIALS TRANSPORTED
INTO THE CELL
OUT OF THE CELL
TRANSPORT IN UNICELLULAR ORGANISMS
-TRANSPORT MATERIALS OVER SHORT DISTANCE, SUCH AS BETWEEN
- BY SIMPLE DIFFUSION, OSMOSIS, ACTIVE TRANSPORT OR CYCLOSIS
(CIRCULATION OR STREAMING OF CYTOPLASM WITHIN THE CELLS)
- ITS CELL MEMBRANE IS IN FULL CONTACT WITH ITS ENVIRONMENT.
SO, THE MATERIALS NEEDED ARE TRANSPORTED DIRECTLY INTO THE
-IN Paramecium sp., GASEOUS EXCHANGE OCCURS BY SIMPLE DIFFUSION.
MATERIALS ARE TRANSPORTED WITHIN ITS CYTOPLASM BY CYCLOSIS.
TRANSPORT IN MULTICELLULAR ORGANISMS
-CELL DO NOT CONTACT WITH EXTERNAL ENVIRONMENT
- THERE ARE LAYERS OF CELLS BELOW THE EPIDERMAL CELL LAYER
-SIMPLE DIFFUSION CANNOT TRANSPORT SUBSTANCES (OXYGEN,
NUTRIENTS, CO2 AND WASTE PRODUCTS) TOB THE BODU CELLS.
-NEED TRANSPORT SYSTEM TO TRANSPORT OXYGEN AND FOOD TO THE
CELLS AND REMOVE CO2 AND METABOLIC WASTES FROM THEM.
LIVING ORGANISMS AND THEIR TOTAL SURFACE AREA TO VOLUME
-THE TOTAL SURFACE AREA TO VOLUME (TSA/V) RATIO : THE TOTAL
EXTERNAL SURFACE AREA OF A STRUCTURE TO ITS CAPACITY
-TSA/V RATIO OF A CELL : THE TOTAL SURFACE AREA OF ITS PLASMA
MEMBRANE TO THE VOLUME OF THE CELL.
-TSA/V OF A MULTICELLULAR ORGANISM : TOTAL SURFACE AREA OF THE
SKIN TO VOLUME OF ITS BODY
-TSA/V IS USED TO MEASURE :
A) SURFACE AREA AVAILABLE FOR GASEOUS EXCHANGE
B) RATE OF MOVEMENT OF SOLUTES TO THE INTERIOR OF AN ORGANISM
- By using a cube, we found that the TSA/V ratio of a cube is
inversely proportional to its size.
Size α 1
-The physical implications are :
a) smaller living organisms have larger TSA/V ratios. A large
TSA/V ratio helps in the efficient gaseous or solutes diffusion
b) larger living organisms have very small TSA/V ratios. A small
TSA/V ration limits the rate of gaseous or solutes diffusion.
- How to overcome the transport problem?
- Organism A : a)unicellular organism
b)has very high TSA/V ratio
c)has cells where nutrient and oxygen molecules
can easily diffuse into the cell and waste products
diffuse out of the cells through its entire cell
-Organism B : a) multicellular organisms
b) has a very low TSA/V ratio
c) less surface area per unit cell for diffusion of
nutrient and oxygen molecules into its
d) impossible for simple diffusion to occur
-Organism C : a) same size as organism B
b) has transport tube linking to the interior cells
c) increasing TSA/V ratio of organism
d) tube transport nutrient, oxygen and unwanted
waste molecules in and out of cells
-Circulatory system transports substances such as nutrients,
water and oxygen to the body cells and removes carbon dioxide
and other nitrogenous wastes from the body cells.
-The circulatory systems of humans and animals consist of 3
a) a medium/fluid – required to carry materials around the
circulatory system (blood, haemolymph)
b) vessels – tubes for the medium to flow through
c) pump – heart that help to propel and circulate the medium
around the body
- 5 million per mm3 of blood
-Tiny (8μm), biconcave, disc shape
-Do not have nucleus, mitochondria or
-Full of haemoglobin
- made in the bone marrow, live for about 120
- Destroyed and recycled in the liver
-Adaptations of erythtocytes:
a) have no nucleus – provide more space for haemoglobin
b) transport oxygen – haemoglobin combine to oxygen and form
c) transport CO2 – haemoglobin combine to CO2 as hydrogen-
d) biconcave, disc shape – increase the TSA/V ratio for optimum
e) small and flexible – can diffuse through narrow capillary walls
Leucocytes in blood
-colorless, do not have haemoglobin
-Larger than erythrocytes, fewer in number
-7000 per mm3 of blood. Raised the number
of leucocytes (leucocytosis), decrease the
number of leucocytes ( leucopenia)
-Irregular shape, have nucleus
-Important in body defence mechanisms against disease
- divided into 2 basic types : granulocytes and agranulocytes
-Have granular cytoplasm and
engulf bacteria by phagocytosis
-Produce in bone
-Divide into 3 types:
a) Neutrophils – form 70% of
- has multi-lobed
- engulf bacteria by
b) Eosinophils – 2-4% of total
- detoxify chemical,
c) Basophils – 1% of leucocytes
Have non-granular cytoplasm,
Divide into 2 types
- Largest of the five types of
white blood cell
- Produce in bone marrow
- Consist 5-8% of all leucocytes
- Have bean-shaped nucleus
- Ingest bacteria by phagocytosis
- Has large, rounded
nucleus and small
amount of non-granular
- Large nucleus contain
genes for antibody
- Produced in lymph
glands and lymphatic
- Produced antibodies
- Are tiny fragments of megakaryocytes (bone
marrow cell) found in the bone marrow.
- Colourless, irregular shape, no nucleus.
- Measures about 2-3µm across.
- Made in the bone marrow and last for about
- Have amoeboid movement
- Important in blood clotting, repairing damaged tissues and
maintain the integrity of blood vessel wall.
- Yellowish liquid which the blood cells are suspended.
- Consist about 90% water, 10% dissolved substances.
- Dissolved substances consist of plasma proteins, dissolved
gases, absorbed food molecules, excretory waste products,
hormones and salts.
- Heat produced by respiration is being absorbed by plasma.
Water • 90% of the plasma
• As a solvent and transport medium
Proteins • Albumins – for viscocity and osmotic balance
• Antibodies e.g. globulin – for immunity
• Clotting factors such as fibrinogen and
Dissolved gases • Consist of CO2 and O2
• Consist of glucose, amino acids, fatty acids,
• Consist of CO2, urea, uric acid, creatinine
Hormones • Adrenaline,insulin,glucagon, antidiuretic
Salts • Consist of dissolved ionic salts;
Content of blood plasma
FUNCTION OF BLOOD AND HAEMOLYMPH IN TRANSPORT
- Functions of blood:
a) transport of materials
b) defence against diseases
FUNCTIONS OF BLOOD IN TRANSPORT
Examples Transported in Transported
in erythrocytes Respiring
Calcium Teeth and
Plasma Liver Kidney
FUNCTION OF HAEMOLYMPH IN TRANSPORT
- Haemolymph is the circulatory fluid in the body cavities of insects
that have an open circulatory system.
- Known as “ insect blood”.
- Contains water, amino acids, sugars, salts and white blood cells
- Help to transport hormones, nutrients, salts and metabolic wastes
around the body.
- Does not contain haemoglobin
- Does not transport oxygen and CO2 in insects, these gases are
transported by the tracheal system.
OPEN AND CLOSED CIRCULATORY SYSTEM
a) Open circulatory system
- found in insects, crustaceans (prawns) and molluscs (snails).
- “blood” pump from heart aorta arteries body
- Haemolymph reach the body cells directly
- Haemolymph diffuses between body cells and re-enters the
heart through open-ended veins.
b) Closed circulatory system
- found in all vertebrates (human, fish) and invertebrates
- blood is pump within a vessel and never comes in direct
contact with the body cells.
- can transport oxygen and other materials faster
THE STRUCTURE OF HUMAN BLOOD VESSELS
- The heart is connected to a series of tubes called blood vessels.
-The main types of vessels : artery, arterioles, capillary, venule and
-Carry blood away from the heart at high pressure.
-Carry blood that is rich in oxygen (except in the pulmonary artery)
- have 3 layered walls consisting of:
a) endothelium – inner layer, single flatten
b) smooth muscles and elastic fibres –
thick middle layer
c) fibrous connective tissue – external layer
-Able to transport blood under high pressure
due to the strength of the thick elastic fibres
-Contract their smooth muscles to decrease
the diameter of the lumen, decreasing the volume of blood flow.
- Relax their smooth muscles to increase the diameter of the lumen
and increase the volume of blood flow.
-Smaller thin walled, branches of the arteries that end in capillaries.
- carry blood from arteries to the capillaries.
-Constrict and dilate to regulate blood flow and pressure.
-Microscopic thin-walled (one-cell thick) blood vessels.
-Carry blood from arterioles to venules.
-Have diameters of about 7-9μm
-Form capillary networks in most of the organs and tissues of the
-Small veins which carry blood from capillaries to the veins.
-Have 3 layered wall : inner endothelium, inner layer of muscle and
elastic tissue, outer layer of fibrous connective
- Have thinner walls than arterioles.
-Carry a slower-flowing blood at low pressure towards the heart.
-Carry deoxygenated blood (except in pulmonary vein).
-Have 3 layered walls, but these layers are thinner and less
muscular than those in the arterial wall. So, they collapse when
-Have internal valves (semi-lunar valves) to prevent a backflow
- Have skeletal muscle to move the blood more quickly.
Artery Capillary Vein
3 layers –
Thick Very thin Thinner than
Away from the
From arteries to
Valve Absent Absent Present
Blood pressure High Decreases from the
arteriole to the
STRUCTURE AND FUNCTION OF THE HUMAN
-Enveloped by a membrane called pericardium.
- Made up of cardiac muscles
-Cardiac muscles are made up of muscle fibres
-Each muscle fibre is made up of
interconnecting muscle cells.
-Muscle cells are joined one to another by
intercalary disc that allow the rapid
transmission of nervous impulses from cell to
cell through the tissue.
-Myogenic, it can relax and contract on its own (do not need nerve
-Has 4 chambers :
a) 2 upper auricles / atria
b) 2 lower ventricles
-A thick muscular wall, called medium septum completely separate
the right side of the heart from its left side.
-The heart functions as 2 separate pumps side by side:
(a) The right side of the heart pumps deoxygenated blood
(b) The left side of the heart pumps oxygenated blood
-Contraction of the atria:
(a) when the right atrium contracts, blood passes into the lower right
(b) when the left atrium contracts, blood passes into the lower left
-Contraction of the ventricle:
(a) when the right ventricle contracts, it pumps blood out into the
(b) when the left ventricle contracts, it pumps blood out into the
-Thickness of the muscular walls:
(a) Atria have thinner and less muscular walls because they only
pump blood down the ventricles.
(b) Right ventricle has to pump blood to the lungs, and therefore
has a thick wall.
(c) Left ventricles has to pump blood to the body and has thickest
-Has 4 valves :
(a) Tricuspid valve
on the right side of the heart
has 3 flaps
prevents the backflow of blood into
the right atrium when the
right ventricle contracts.
(b) Bicuspid valve/ mitral valve
on the left side and has 2 flaps
prevents the backflow of blood into
the left atrium when the left
(c) Semi-lunar valves
found at the base of pulmonary artery and aorta
prevent the backflow of blood into the right and the left
ventricles when they relax.
Bicuspid valve (3D)
Upper part – tricuspid valve
Lower part – bicuspid valve
THE CIRCULATION OF BLOOD IN HUMAN
-Humans have closed, double circulatory system:
a) It is closed because the blood is contained within the heart and
the blood vessels, does not come in direct contact with the
respiring body cells.
b) It is double circulatory system because the blood passes
through the heart twice for each complete circuit of the body.
-Consist of 2 sub-circuits:
(a) Pulmonary circulation – heart lung heart
(b) Systemic circulation – heart rest of the body heart
- Deoxygenated blood from the heart is pumped from the right
ventricle through the pulmonary artery.
-Oxygenated blood from the lungs then return to the left atrium
through pulmonary vein.
- Supplies blood to all parts of the body, except the lungs.
-Oxygenated blood is pumped from the left ventricle into the aorta
before it is distributed by:
(a) subclavian arteries to the arms
(b) carotid arteries to the neck and head
-Superior vena cava collects deoxygenated blood from the upper
part of the body and return it to the right atrium.
-Inferior vena cava collects deoxygenated blood from the lower
part of the body and returns it to the right atrium.
-Heart receives blood form a pair of coronary arteries leading from
-The flow of blood during blood circulation is maintained by:
a) the pumping action of the heart – ventricles press the blood
through the arteries into the capillaries.
b) contraction and relaxation of skeletal muscle around the veins
during the normal body movements to propel the blood to the
c) inhalation movements – during inspiration, the thoracic pressure
is reduced, and this aids in drawing blood back into the heart.
THE PUMPING OF HEART
- Two atria contract simultaneously:
a) blood from the right atrium is forced into the right ventricle
b) blood from left atrium is forced into the left ventricle
- Two atria relax simultaneously:
a) left atrium receives blood from the pulmonary veins
b) right atrium receives blood from the superior upper part of
body) and inferior (lower part of body) vena cavae.
- After a slight pause, two ventricles contract (systole)
a) blood in the right ventricle is forced into the pulmonary artery
and blood in the left ventricle is forced into the aorta.
b) Blood in the right ventricle and the left ventricle is prevented
from flowing back into the atria by the closure of bicuspid
c) The simultaneous closure of the two valve will produce “lub”
-When 2 ventricles relax (diastole):
a) the volume of the ventricles increase; drawing in blood from
b) blood in the arteries (pulmonary artery and aorta) is prevented
from flowing back to the ventricles by the closure of both the
two semilunar valves, produce “dub” sound.
-A heartbeat consist of a systole (“lub” sound) and a diastole
- Normal heartbeat – 72 times/minute
BLOOD PRESSURE AND THE REGULATORY MECHANISM
- Blood pressure is the force that blood exerts on the walls of the
blood vessels, which is measured in millimetres of mercury
- Caused by the contraction of the heart and by the muscles that
surround blood vessels.
- Blood pressure in the arteries is highest when the ventricles
contract (systole) and force the blood into the pulmonary artery
and the aorta.
- Blood pressure decreases when the two ventricle relax (diastole).
-Normal blood pressure : 120/80 mmHg , 120 over 80
- The first number represent the pressure when the ventricles
-The second number represents the pressure when the ventricle
-In human, blood pressure is regulated by:
a) nervous system – send impulse to speed up or slow down the
b) kidney – regulate blood pressure by controlling the amount of
fluid in our blood. When blood pressure is too high, kidneys
remove water from the blood (less volume of blood), blood
pressure become lower.
REGULATION OF BLOOD PRESSURE BY THE NERVOUS SYSTEM
-Baroreceptor / stretch receptors – groups of nerve fibres within
the walls of the carotid sinus (a swelling of the internal carotid
artery) and the aortic.
-If blood pressure in the arteries is high:
a) the baroreceptors detect it and send impulses from the sensory
nerves to the cardiovascular centre in the medulla oblongata of
b) Cardiovascular centre of the brain sends impulses (in the vagus
nerve of the parasympathetic nervous system) to the heart to
decrease the heart rate and also the cardiac output (volume of
blood pumped by the heart).
c) At the same time, the cardiovascular centre sends nervous
impulses to relax the smooth muscles of the arterioles,
causing the arterioles to dilate (vasodilation) and reduce the
resistance to blood flow.
d) A reduced heart rate, a lowered cardiac output and a
vasodilation of the arterioles will help to reduce the blood
Decreased Heart Rate
and cardiac output
muscle in the
arterioles to dilate
-If blood pressure drops too low:
i) The baroreceptors detect it and stimulate the cardiovascular
centre to send the nervous impulse (via the sympathetic nervous
• to increase the heart rate (via the sympathetic nerve)
• to stimulate the smooth muscles in the arterioles to contract
(vasoconstriction) to decrease flow of blood.
ii) An increased heart rate and a vasoconstriction of the arterioles
will help to increase blood pressure.
CIRCULATORY SYSTEMS IN OTHER ANIMALS
e.g. humans, birds
-Single circulation – blood passes through the heart only once in
a complete circulation of the body
-Double circulation – blood passes through the heart twice in a
complete circulation of the body
•lizards, snakes, and turtles have incomplete septums,
oxygenated blood and deoxygenated blood may
mix to some degree.
•In crocodiles a complete septum and a valve prevent this
- Has a simple two-chambered heart, consisting of an atrium and
ventricle that are separated by atrio-ventricular valve.
-Atrio-ventricular valve prevents the backward flow of the blood
from the ventricle into the atrium.
a) ventricle of the heart pumps deoxygenated blood to the capillary
network of the gills to be oxygenated.
b) Arteries carry the fully oxygenated blood from the gills to
various parts of body capillaries.
c) Deoxygenated blood from the body capilaries returns to the
atrium of heart.
-Fish have a
a) single circulation – blood is pumped through the heart only
b) closed circulation – blood is always contained within the
heart and blood vessels.
-Disadvantage of the single circulation – single heart has to pump
blood through the gill capillary network and the body capillary
network. Thus, reduce blood pressure and sluggish flow of blood
- Has 3 chambered heart, consist two atria and one ventricle
• Pulmonary artery carries blood
from the ventricle to the
pulmonary capillary network,
where gas exchange occurs.
• Pulmonary vein returns
oxygenated blood from the lungs
to the left atrium of the heart
• Vena cava returns deoxygenated
blood from the systemic capillaries
to the right atrium.
• Single ventricle receives both
oxygenated blood and
• When the ventricle contract, a mixture of oxygenated and
deoxygenated blood is pumped into both the pulmonary artery
• incomplete double circulation – although blood is pumped through
the heart twice in a circulation,
there is a mixing of oxygenated
and deoxygenated blood in the
• closed circulation – blood is contained within the blood vessel
-Advantage for incomplete double circulation is higher blood
pressure, so the flow of blood is more efficient compared to fish.
-Have 4-chambered heart that completely separate oxygenated and
-Septum of the heart is complete, providing 2 separate circulatory
Pulmonary circulation – right atrium and right ventricle
receives deoxygenated blood from
the body and send it to the lungs
Systemic circulation – the left atrium and left ventricle receive
oxygenated blood from the lungs and
sends it to the body tissues.
-Birds have higher metabolic rate than humans, the pulse rate of
chicken can reach 400 beats/minute.
-Its ventricle have more muscle mass and less chamber space than
-Importance of blood clotting:
a) prevents excessive blood loss which make blood pressure
b) prevents the entry of microorganisms and foreign particles
into the body
c) forms scabs and helps in the healing of wounds
d) maintains the circulation of blood in a closed system
MECHANISM OF BLOOD CLOTTING
- Blood flowing in blood vessels is prevented from clotting by a
substance called heparin (family of carbohydrate) found in the
-Blood clotting is initiated by the:
a) clotting factors from damaged cells
e.g. fibrinogen, prothrombin, thromboplastin, calcium ions
b) Collagen fibres from damaged blood vessel wall
- Mechanism of blood clotting:
IMPAIRED BLOOD CLOTTING MECHANISM
a) Deficient in calcium and vitamin K:
o It will take a longer time than normal
o cause bleeding
Blood is unable to clot because the deficiency of blood
Cause bleeding or death
Thrombosis is the formation of a clot or thrombus inside a
blood vessel, blocking the flow of blood.
The blockage stops the tissues from receive blood flow and
cause damage to the tissues in that area
A clot formed in coronary artery cause heart attack.
A clot formed in the brain cause strok.
Heart attack Strok
-The space between tissue cells –
-Interstitial space is filled with a
colourless liquid – interstitial fluid
-The formation of interstitial fluid and
a) Blood enters the arterial ends of the
capillary network under high pressure
b) Endothelial cell walls of the capillaries act as filter. Large cellular
components (red blood cell) and large protein molecules cannot
pass through. Only water and dissolved substances of
the plasma (oxygen, products of digestion and hormone) can
diffuse out of the cell.
c) Blood plasma diffuse out into the interstitial spaces to form
d) The process of producing interstitial fluid from the blood is
e) The interstitial fluid circulates among the tissue cells and
returns to the blood circulatory system in two ways:
(i) passes into the venous end of the capillaries
ii) drain into the lymph capillaries as lymph
f) Lymph and interstitial fluid have the same composition, the
difference is interstitial fluid is found between the cells, while
lymph is found inside the lymph vessel.
Blood Plasma Interstitial fluid Lymph
Appearance Red Light yellow Pale brown
Location Within the heart, arteries,
veins and capillaries
Originate from Bone marrow,
Plasma Interstitial fluid
and fatty acids
absorbed by the
Function Transport and
Moved by Pumping of the heart, muscle
contraction, breathing action
Circulates around the
body and back to the
Out of the arterial
end and returns into
the venous ends of
From the tissues
and towards the
Contents Blood Plasma Interstitial fluid Lymph
Platelets X X X
Leucocytes X X
erythrocytes x x x
- The importance of interstitial fluid:
a) tissue fluid fills the interstitial spaces between the tissue cells,
providing them with a stable external environment
b) nutrients and oxygen from the bloodstream in the capillary
network diffuse across the capillary walls into the interstitial fluid
and then into the tissue cells.
c) waste products that accumulate within the active cells diffuse
in the opposite direction across the interstitial fluid from the cells
to the capillaries.
STRUCTURE OF THE LYMPHATIC SYSTEM
-Lymph is found inside the lymph vessels.
-The composition of lymph is similar to interstitial fluid but with
-Main structures of the lymphatic
a) Lymphatic capillaries:
- larger in diameter than the
- located next to blood
capillaries in tissue spaces
- very permeable to tissue
- found as lacteals in the villi
of the small intestine
b) Lymphatic vessel
- formed from lymph capillaries
- similar as veins (have 3 layered walls), but have thinner
walls and more valves
- carry lymph away from the tissues
c) Lymph node
- small round or oval structures
- contains a network of fibres and irregular channels acting
like a filter
- filter lymph when it
flows through the
- eliminates bacteria
and cellular debris by
- an organ located on the left side of the abdomen near the
- produce lymphocytes, filters the
blood, store blood cells, destroy old
e) Lymph ducts (larger lymph vessel)
- lymph vessels drain their contents
back into the bloodstream
- Thoracic duct (left lymphatic duct)
and right lymphatic duct.
-Movement of lymph within the lymphatic system;
a) interstitial fluid drains into the lymph capillaries to form lymph
b) lymph capillaries join together to form larger lymphatic vessel
c) the walls of the lymphatic vessels contain
valve-like pores that allow the entry of cell
debris and bacteria
d) the contraction and relaxation of the
skeletal muscle contract and relax the
lymphatic vessel, pushing lymph to the
e) Semilunar valves within the lymphatic
vessels keep the flow of lymph in one
f) Lymph nodes remove the suspended solid and bacteria from
the lymph by phagocytosis
g) The lymphatic vessels return the lymph to the heart via two ducts:
i) Right lymphatic ducts
- drain lymph from the right arm, right side of head and the
thorax and opens into
the right subclavian vein
near the heart
ii) the thoracic duct (left
lymphatic ducts) drains
lymph from the rest of the
body into the left
subclavian vein near the
- Lymph is moved along the lymph vessel by:
a) Hydrostatic pressure of interstitial fluid- push lymph along the
b) Contraction of skeletal muscle – lymph flow along the lymphatic
c) Valves within lymphatic vessel – lymph flow away from the tissue
to the heart in one direction
d) Inhalation – reduce pressure in thoracic cavity and drawing lymph
towards the thorax.
Lymphatic capillaries Lymphatic vessel Lymphatic nodes
Right lymphatic duct
Left lymphatic duct
-Function of lymphatic system:
a) transport interstitial fluid back to the bloodstream
b) distributes fluids and nutrients in the body and drains excess
fluids and protein so that tissues do not swell up
c) transport fat and fat-soluble vitamin from small intestine into
the blood circulation
d) provides immunological defence against disease by:
(i) produce lymphocytes and antibodies to fight and destroy
(ii) filtering out microorganisms and other foreign substances
from the lymph by the lymph nodes and from the blood by
WHEN INTERSTITIAL FLUID FAILS TO RETURN TO THE
-Too much interstitial fluid is produced, but little or none is
reabsorbed back into the circulatory system.
-Cause the organs and tissues of the body to swell up- oedema
-Oedema can be caused by:
a) increase in the capillary blood
pressure, forcing an excess fluid
leakage to the interstitial space
b) blockage of the lymphatic vessel
which slows down the drainage
of excess interstitial fluid.
-Elephantiasis – caused by the blockage of the body’s lymphatic
system by certain parasitic round worms leading to oedema.
ROLE OF THE CIRCULATORY SYSTEM IN BODY DEFENCE MECHANISM
-First and second lines of the defence mechanism:
a) nonspecific – they do not distinguish infectious pathogens
b) inborn – they are natural built-in defences
- for example :skin – act as barrier to the pathogens
: phagocytes –engulf pathogens
c) provide immediate protection against invading pathogens.
-Third line of defence mechanism:
a) specific – distinguish specific pathogens. For example,
lymphocytes produce specific type of antibody to fight
b) Acquired and developed
c) takes a longer time to be effective, but remember the past
infections. So, it can be better prepared for future invasions by the
same type of pathogens.
FIRST LINE DEFENCE
• provides a continuous layer
protect a whole body.
• Few microorganisms can
penetrate the layers of dead
cells at the surface of the skin.
A cut in the skin allow the
microorganisms to enter the body.
• Blood clots plug the wound and prevent the entry
• lines all tissues and organs such as respiratory,
digestive, urinary and reproductive tracts.
• secrete mucus, which is thick, slippery liquid that
protect the membrane and keep it moist and soft.
• protect the interior surfaces of the body that may be
exposed to pathogens
-Both the skin and mucous membrane are nonspecific
a) use the same barrier against all types of
b) not directed against any particular pathogens
CHEMICALS USE BY SKIN AND MUCOUS MEMBRANE
• Excreted from sweat glands contains lysozyme and
acids that destroy harmful bacteria and inhibits the
growth of fungi.
• also present in tears, saliva and nasal secretion
• low pH
• prevents the growth of certain microorganisms
• trap microorganisms and dirt particles.
• little hair that carry the mucus,
trapped microorganisms and dirt
towards the glottis to the throat
- Acid in gastric juice
• kills microorganisms present in
food or water on in swallowed
SECOND LINE DEFENCE
-Take action when pathogens can penetrate the skin
or mucous membrane.
-Nonspecific immune response because use same
method of defence to all type of pathogens.
-The nonspecific immune response include:
a) phagocytosis – carried out by white blood cells such
as neutrophils, macrophages and
b) natural killer cells – destroy infected cells and pre-
c) Inflammation – involve redness, heat, swelling, pain
d) Fever – high temperature kill bacteria by
denaturing their protein and help healing
-Phagocytosis (phago = eat; cyte = cell) attack,
engulf and destroy pathogens
-Two common types of phagocytes are neutrophils and
• circulate freely through the blood vessels
• squeeze between cells of the capillary wall to reach
the site of infection, attracted by the chemicals
released by the microorganisms (chemotaxis).
• first phagocytes to arrive at the injured tissues before
• another type of phagocyte developed from
monocytes (white blood cells)
• longer-lived and arrived at the inflamed site some
3-7 days later after the neutrophils.
THIRD LINE OF DEFENCE
- Immunity : ability of the human body to resist infection
-Immune response : body’s defence reaction when an
antigen is recognized and specific antibodies are
produced by lymphocytes to defend against
-Antigen : foreign protein molecule (bacteria, virus,
fungi) that enter the body and stimulate the
production of antibodies
-Antibody : a protein substance produced by immune
system to recognize antigen.
: Y shaped protein molecule that also known
: function – destroy or weaken a pathogen and
neutralise its toxin
-2 white blood cells that involved:
a) lymphocytes – produce antibodies
b) macrophages - phagocytosis
- Antigen recognition and the production of antibodies
takes place when:
WAYS WHICH ANTIBODIES HELP TO DEFENSE BODY
-Antibodies and antigens stick together and the
microorganisms clump together in large numbers
making the antigens harmless.
-The inactive pathogens are then ingested by
- An antigen is covered with antibodies which make it
easier for ingestion by phagocytes.
-An antibody-coated pathogen can be made to burst
(cell lysis), killing it before being ingested by phagocytes.
Cell produce from
- Antibodies bind to the toxins (antigens), neutralise the
poison of the toxin.
-When an antibody binds to a toxin, it is called antitoxin
-The neutralised toxin is then ingested by the
-Virus and bacteria are similarly neutralised to prevent
them from attach and penetrate the body cells.
- Antibodies bind to the soluble antigens, cause them
- Then, they will be ingested by phagocytes.
VARIOUS TYPES OF IMMUNITY
-After an initial infection, some lymphocytes are kept
in the body as a “memory”. This helps the body to
defend itself against further attacks by the same
-As this “memory” may last for years, the body is said to
be immune to the disease.
-There are 2 types of immunity:
a) active immunity
b) passive immunity
Active immunity Passive immunity
• Acquired when
lymphocytes in the
body are activated by
antigens to produce
• Occur when a person
immune to an antigen by
antibodies from another
person or animal.
• Lasts for a long time • Lasts only for a short time
as the antibodies
eventually die off or
removed from the body as
- Some vaccines are made from:
a) live attenuated (weakened) pathogens – measles,
mumps, rubella, chickenpox
b) killed pathogens – influenza, Japanese encephalitis
(J.E), hepatitis A, typhoid fever
c) toxoid – bacterial toxin that has been weakened
and no longer toxic – tetanus, diphtheria
EFFECTS OF HIV ON THE BODY’S DEFENCE MECHANISM
- HIV : H – for Human, because it infect humans
I - Immunodeficiency, because virus attack the
body’s immune system, weakening it so that
it cannot fight other deadly disease
V – Virus belong to the group, retrovirus
- AIDS – Acquired, person get HIV from another infected
- Immune, refer to the body’s defence system
- Deficiency , making the immune system
- Syndrome, refer to a group of illness
- When the immune system is weakened:
a) the body becomes vulnerable to a variety of
infections and cancers.
b) other infections take advantage of the weakened
immune system. These called as “ opportunistic
c) the body becomes so weak, and the person dies.
- Transmission of HIV by:
a) direct contact with infected blood
b) sexual contact with an HIV-infected person
c) HIV-infected mothers to infants during pregnancy,
delivery or breastfeeding
d) sharing needles with drug users who are infected
- HIV is not transmitted
a) by insect bites
b) through the air
c) hugging, touching, handshaking
d) living in the same house
e) sharing food and water
f) sharing cup, glass, plates etc.
TRANSPORT OF SUBSTANCES IN PLANTS
- Transport system is necessary because:
a) CO2 is absorbed and transported to
b) O2 is released from photosynthesising cells into
c) water and minerals from the roots have to be
transported to the leaves
d) photosynthetic products (sugar, amino acids)
have to be transported away from the leaves
for storage and to other tissues.
- Transport functions are carried out by xylem and
VASCULAR TISSUE IN STEM, ROOT AND LEAF
- Consist of phloem and xylem.
- Roles of vascular tissue:
a) xylem – transport water
support the plants
b) Phloem – transport nutrient
- Vascular bundle
• strand of conducting tissue
(xylem and phloem)
• Stem – phloem is located
outward facing the
epidermis, xylem is toward the centre.
• Leaf – phloem facing at the lower part, xylem
at the upper part.
- A mature vascular bundle consist of xylem, phloem
and cambium. Cambium separate the xylem and
STRUCTURE OF VASCULAR TISSUE
- The main tissues in a stem of a dicot :
b) cortex, that contain collenchyma, chlorenchyma
c) vascular bundle, that contain phloem and xylem
d) the pith
-The vascular bundles in the stem of a dicot are
arranged in a ring.
- The cambium is sandwiched between the xylem
-Cortex is located outside of the vascular bundle ring
in the stem.
- The pith is the tissue located inside the vascular bundle
- Parenchyma- cells with thin primary walls that retain
- Collenchyma - cells with thick primary walls that
retain their protoplasm
- Sclerenchyma- cells with lignified secondary walls
that have lost their protoplasm at
maturity, i.e. are 'dead'
- Chlorenchyma - Containing Chloroplast
VASCULAR TISSSUE IN THE LEAF OF A DICOT
- Vascular bundle consist of:
a) xylem – faces the upper epidermis
b) cambium – that divides to produce xylem and
c) phloem – faces the lower epidermis
VASCULAR TISSUE IN THE ROOT OF A DICOT
- Vascular tissue is packed in the centre.
- Other structures observed in the root:
a) root hair – extension of the epidermal cells
- increase absorption of water by the
b) epidermis – absorption of water and minerals
c) cortex – consist of endodermis and parenchyma cell
that store starch.
d) pericycle – layer of parenchyma cells inside the
endodermis where lateral root originate
RELATING THE STRUCTURE OF XYLEM TO TRANSPORT
- Functions of xylem:
a) transport water and dissolved
minerals from the root to
other parts of cell (one way).
b) provide mechanical support
- Xylem consist:
c) fibre (rigid secondary cell wall
for support and protection)
d) parenchyma (store food)
• Dead cells that form hollow tube, which connect
the root to the leaf.
• Deposited by lignin to strengthen it and support
• The structure of xylem vessel is adapted to
transport water because :
o it has continuous lumen without any walls and
protoplasm within it to allow the flow of water
and minerals salts
o the walls are lignified to provide strength and
prevent the water from collapsing
• Dead cells when matured
• Long, slender cells with tapered, overlapping end
• Have thick, hard, lignified secondary cell wall
• Smaller lumen than xylem vessel
• No sieve plates at the end walls
- The movement of water in tracheids:
a) water moves sideway through the pits in adjacent
tracheid cells before going upward
b) movement of water upwards is slower than in
RELATING THE STRUCTURE OF PHLOEM TO TRANSPORT
- Transport food such as sugars and amino acids from
the leaves for storage in stem and root
- Transport food from storage in roots to other parts of
- 2-way flow
- Components of phloem :
a) sieve tube
b) companion cells
a) Sieve tube
- made up of a single row
of elongated and thin-wall
living cells called sieve tube
- A mature sieve tube has only
thin layer of cytoplasm, no
nucleus or central vacuole,
lost most of its organelles
- Sieve plates separate sieve
tube cells at both ends.
- Sieve plates allow cytoplasmic
connections between vertically-stacked cells that will
transport food by diffusion and active transport.
b) Companion cell
- lie next to each sieve tube cell
- has a nucleus, endoplasmic
reticulum, ribosomes and
- provide metabolic support for the
sieve tube cells in the transport of
REMOVING A RING OF PHLOEM TISSUE FROM A
- Phloem can be removed by cutting a ring of bark and
removing it from the stem.
- This “ringing” cuts off the supply of food downwards
beyond the ring.
- Food that is transported from the leaves down the stem
in the phloem accumulates above the ring.
- After a few weeks, the bark above the ring swells.
- This shows that sugar transported downward in the
- Movement of sugars and other organic materials from
one place to another within the plant body
a) distribute food to other parts of the plants such as
seed, root, tuber.
b) without translocation, plants would not be able to
metabolise food for energy, growth and
-The loss of water by evaporation from the parts of
plants through the stomata of the leaves.
a) mainly through the open stomata – 90% of water
b) waxy cuticle – very little water escape through the
cuticle of the leaves
c) lenticels of woody stem
PROCESS OF TRANSPIRATION
- There are intercellular air spaces among the spongy
- Spongy mesophyll cell has
- Water evaporates from
these cells into the
intercellular spaces and
diffuse through the stomata
to the drier air outside the
- As these border of mesophyll cells lose water, their cell
sap becomes more concentrated and therefore draws
water by osmosis from the cells deeper inside the leaf.
- These cells in turn draw water from the xylem of the
plant veins by osmosis.
-Water forms an unbroken water chain (by cohesion and
adhesion force of water molecule) from the outer
surface of leaves to the roots.
-As the water evaporates from the plant leaves, they
attract other water molecules which are still in the plants
to the top.
THE IMPORTANCE OF TRANSPIRATION
- The roles of transpiration:
a) cooling the plants
As water evaporates from the leaves, it remove
heat from the plant in the form of latent heat of
vaporisation, thereby cooling the plant
b) Provide support by turgor pressure
because water diffuse from higher concentration
to lower concentration, all the cells in the plants
c) Transport water and mineral salts
Transpiration create a transpiration pull, lifting
water and dissolved mineral salts up the plant
from the root to the leaf.
- Negative effect of transpiration:
a) if the rate of transpiration exceeds the intake of
water by the roots, plants growth would be affected
b) any excess loss of water causes the plant to wilt and
THE PATHWAY OF WATER FROM SOIL TO THE LEAVES
MOVEMENT OF WATER FROM SOIL TO ROOT
- The cell sap of root hairs is more concentrated than
-The high solute concentration of the cell sap is due to
the active transport of the solute molecules into the
-Water moves from the soil water into the cell sap of root
hair by osmosis.
-When water enter the vacuole of the root hair cell:
a) the cell sap becomes dilute and its concentration
and osmotic pressure are reduced
b) the turgor pressure of the cell increase and reduce
its suction pressure
c) the cell sap become hypotonic the cell sap of
-Water from hypotonic root hair cell sap move to
adjacent hypertonic cells.
-Therefore, water move out from the root hair cell into the
adjacent cells, cortex and then into the xylem.
PATHWAY OF WATER UP THE STEM
-The movement of water in the xylem up the stem is
a) root pressure
b) transpiration pull
c) cohesion- adhesion theory of water
a) Root pressure
- the ‘pulling’ of water into the xylem from the
surrounding cells produces a hydrostatic pressure
inside the xylem, forcing water upwards.
- this positive pressure is called root pressure.
b) Transpiration pull
- when water evaporates from mesophyll cells, their
cell sap becomes more concentrated.
- these mesophyll cells in turn draw water by
osmosis from the cells found
in deeper inside the leaf.
- these inner cells which are
adjacent to the veins draw
water from them by osmosis.
- the column of water is
continuous from the root up
to the leaves
- as the mesophyll cells ‘suck’ water from the xylem
vessel, the whole column of water is pulled up from
root to leaf (due to cohesive and adhesive of water
- The pulling force is called transpiration pull
c) Cohesion-adhesion theory of water
- the continuous flow of water through the xylem
depends on two important properties:
i) cohesion – attraction between water and water
ii) adhesion – attraction between water and xylem
- this is why water forms a continuous water column
up the xylem vessel while being sucked up by
the transpiration pull.
EXTERNAL CONDITIONS AFFECTING TRANSPIRATION
- The amount of water lost from the plant in transpiration
a) light intensity
c) relative humidity
d) air movement
a) Light intensity
- guard cells regulate the size of the stomata
i) under high light intensity, the stomata openings
enlarge and transpiration increase
ii)under low light intensity, the stomata opening
decrease and transpiration decreases
- the rate of transpiration is directly proportional to
the intensity of light.
- High temperature increase the kinetic energy of
water molecules which increases the rate of
diffusion through the stomata
- the rate of transpiration is directly proportional
c) Relative humidity
- intercellular air spaces in the leaf are saturated with
- water vapour diffuse from the intercellular space to
the air outside.
- this saturated water vapour diffuse out of the leaf at
i) higher rate if the air outside is dry (higher
ii) lower rate if the air outside is damp (lower rate
d) Air movement
- In still air, water vapour that diffuse out through the
stomata forms a layer of still moist air around the
- Moist air decrease the rate of water vapour diffusion
and drop the rate of transpiration.
- Moving air carry away this layer of moist air formed
around a leaf and increase the rate of transpiration.
- The rate of transpiration is directly proportional to
the velocity of the air current.
THE OPENING AND THE CLOSING OF THE STOMA
- The uneven thickening of the outer and inner wall of
the guard cells provide a mechanism for the opening
and the closing of the stoma.
- The inner concave wall of each
guard cell is very thick, but
the outer convex wall is thinner
- For high light intensity, the rate
of photosynthesis increase and
the guard cells absorb water
and become turgid.
- Water in each guard cell push the thin outer wall
that enlarge the stomata opening.
- Under poor light, the turgor pressure of the guard cells
drop, it become flaccid and the stoma become
smaller or closes.
HOW STOMA OPENS IN DAYLIGHT
- Photosynthesis take place in the guard cell
Osmotic pressure in
guard cell increase
Water enter the guard
cell by osmosis
Guard cell become
- Photosynthesis take place in the leaf cells
CO2 in the leaf cell
pH goes up
Starch in the cell is
converted into sugar
HOW STOMA CLOSES AT NIGHT
- Photosynthesis in guard cells stop
sugar in guard
Osmotic pressure in
guard cell decrease
Water leaves guard
cell by osmosis
- Photosynthesis in the leaf cells stop
of CO2 in
pH goes down
Sugar is convert to
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