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Osmosis
Osmosis is defined as the movement of solvent particles (usually water) from a region of
high concentration to a region of low concentration through a partially permeable
membrane
...

So, water moves from an area where it is in high concentration (abundant), to an area where
it is in low concentration (less abundant) until both areas have the same concentration of
water
...
Osmosis occurs until there is an equal
concentration on either side (until equilibrium is met)
...

The arrows represent the direction in which water molecules will move across the semipermeable membrane
...
This tendency is measured as the water
potential
...
Pure water has the highest

water potential
...
Because of this, the more solute particles that are present, the lower the water
potential of the solution

How Osmosis Applies To Organisms
Cell membranes are often compared with a Visking tube as they only allow certain substances
to pass through them
...

The body is made up of approximately 70% water
...
This means that a lot of osmosis occurs within the body as the concentration of the
cytoplasm may vary from time to time
...
A hypotonic solution has higher water concentration
than the contents of the cell
...

Osmosis and animal cells
Because animal cells have no cell wall, they are not strong enough to withstand the pressure
caused from swelling
...
The bursting of a cell is called lysis of the cell
...
In this case, the cell will most likely
shrink and become shrivel (flaccid)
...
The cell remains normal
...

Unlike an animal cell, plant cells have a cell wall
...
As water moves in
the plant and the concentration of water in the plant gets greater, eventually equilibrium is
reached (equal concentration of water inside and outside the cell)
...
This

water movement inside plants is essential for building pressure, called turgid pressure
...
In a
highly concentrated solution, plant cells will become shrivelled
...
Plasmolysis occurs when the cell membrane
surrounding the cytoplasm shrinks further and further away from the cell wall
...


Many times the movement of ions requires movement against a concentration gradient,
this is called active transport
...
Many times plants (roots) require
more minerals from their surroundings although they have a greater concentration of
minerals inside their cells already
...

Previous | Next

Introduction To Plant Nutrition
All living things feed/need nourishment
...
This food is in the form of a sugar (often
glucose)
...
The end products, organic compounds, are composed from the simple inorganic

compounds water and carbon dioxide
...

The two raw materials required for photosynthesis are acquired by different means
...

Photosynthesis occurs inside special organelles called chloroplasts
...
The conversion of light energy to chemical energy is done by
the chloroplast
...
The glucose is dissolved and transported throughout the plant
via vascular tissues called phloem
...

The whole process of photosynthesis involves two stages: the light dependent stage and the
light independent stage
Also referred to as the light reactions, this stage of photosynthesis occurs on the thylakoid
membrane of the chloroplast
...
The light energy is used to split the water molecule (H2O) into
hydrogen and oxygen (photolysis)
...
)
The equation used to depict photolysis is:

(oxygen is given off as a by-product)
The energy produced in the light stage is used to produce ATP (adenosine triphosphate)
...
The oxygen that
is given off is released from the plants
...

The hydrogen produced is attached to NADP (nicotinamide adenine dinucleotide
phosphate) to form NADPH, where H signifies the hydrogen atom
...
NADPH is
therefore referred to as an electron carrier as it only transports the hydrogen electron from
one place to another
...
This stage of
photosynthesis is also known as the Calvin Cycle or the dark reactions
...
This reaction uses the energy (in the form of
ATP) produced from the light stage to provide the energy needed to combine the hydrogen
(also produced from the light stage) with carbon dioxide to form glucose (C6H12O6)
...
The overall process is
represented by the equation below:

Word equation for overall reaction:
Chemical equation for overall equation:

Recall:
-Carbon dioxide is obtained from the air by the leaves of the plant via diffusion
...

-Sunlight is absorbed by the chlorophyll in the leaves and supplies the light energy needed for
the process
...
Oxygen is merely a by-product
...
Three major factors that will be discussed
are light intensity, carbon dioxide concentration, and temperature
...

Effect of light intensity on the rate of photosynthesis
Photosynthesis is dependent on light from the sun; as the light intensity increases, the rate of
photosynthesis increases at a similar rate
...
This is called light saturation and is usually reached at 10000 lux
...
Carbon dioxide concentration in the atmosphere is
about 0
...
There is also a point where any further increase in
carbon dioxide concentration will not lead to an increase in the rate of photosynthesis
...
As with all enzyme controlled reactions there is an optimum

temperature
...


Other factors that may affect photosynthesis include:
-Chlorophyll concentration
-Water
-Pollution
-The stomata on leaves (whether they are open or closed)

Investigating Photosynthesis
Several experiments may be carried out to test what substances/conditions are necessary for
photosynthesis to take place
...
To confirm the products, additional tests may also be
done
...
If the substance missing is
indeed essential for the photosynthetic process, there will be some hindrance to the process
...

If tests are being carried out to determine whether a leaf photosynthesizes, the leaves have to
be de-starched before experimentation
...
The iodine test can then be performed to verify the absence of
starch in the leaf
...

This glucose is often converted to starch
...
Iodine solution is used for the starch test and a
positive result is indicated by a blue-black colour after iodine has been added to the leaf
...


The Leaf
Being the main food-making organ in plants, leaves are often green in colour as they contain a
lot of chlorophyll
...
In these veins, there
are vascular bundles which contain xylem vessels as well as phloem which carry substances to
and from the leaf
...


TRANSVERSE SECTION THROUGH PART OF A LEAF

Functions of parts of the leaf
Epidermis- protects the inner layers of cells in the leaf
...
The
cells of the upper epidermis often secretes a waxy substance (cuticle) that stops water from
evaporating from the leaf
...

Stomata- singular stoma, these are small holes on the leaf that are surrounded by guard
cells
...
The guard cells contain chloroplasts
...
(meso- middle, phyll- leaf)
...

-Palisade layer- these cells are closer to the top of the leaf and are arranged like a fence/
palisade
...

Vascular bundle- this makes up the vein in a leaf
...

-Xylem vessels- these carry water around the plant
-Phloem tubes- carries food around the plant that has been made by the lea

Introduction To Enzymes
Enzymes exist in both plant and animal cells
...

Enzymes are known as biological catalysts
...
They are referred to as biological
catalyst because enzymes are protein molecules made by living organisms
...
The substrate is simply the substance that is
being broken down while the product, as the name suggests, is the end result
...
Without enzymes in a
living organisms body several reactions would occur too slow to sustain life
...
The name an enzyme receives is often done according to the substrate
whose breakdown is being catalysed
...

Properties of Enzymes
-Enzymes are protein in nature
...

-Enzymes are biological catalysts
...
The presence of enzymes does not alter the nature of the end product of the reaction
...
A very small amount of a catalyst brings about
the change in a large amount of substrate
...
That’s how specific they are
...
g
...

-Enzyme activity is affected by factors such as pH, temperature, substrate
concentration and enzyme concentration
...
Some enzymes work best in acidic conditions
(low pH), while other enzymes work best in alkaline conditions (high pH)
...
Above and below these temperatures,
respectively, there may be very little or no enzyme activity
...
This is referred to as the optimum
temperature
...
However since
enzymes are protein structures, they may be denatured by excessive heat
...

-The substrate concentration refers to the amount of substance that needs to be broken down
...
If there is a low enzyme substrate concentration, the reaction rate will be quite
slow
...


ffect Of Temperature On The Rate Of Reaction

THE ABOVE GRAPH SHOWS THE EFFECT OF TEMPERATURE ON REACTION RATES
At region A on the graph, the rate of reaction steadily increases
...
The enzymes are denatured, slowing the
rate of reaction (e
...
photosynthesis)
...


Effect Of PH On Rate Of Reaction

Enzymes are pH sensitive
...
The optimum pH usually occurs at about 7
(neutral)
...
g
...


The graph above shows the activity of pepsin in comparison to that of trypsin – an enzyme
that works best in an alkaline environment
...
See table below for
list of where substances are absorbed
...
ATP is the form of
energy used in the body and provides cells with all the energy needed to carry out their daily
functions such as drive metabolic reactions which must occur fast enough if life is to be
sustained
...


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Gaseous Exhange
Gaseous exchange (e
...
breathing) as the name suggests involve the release/ transfer of
gases
...
Gaseous exchange provides these conditions by the trapping of oxygen from the
surroundings and the release of carbon dioxide to the surroundings
...

Gaseous exchange mechanisms
We know that all living things must metabolize energy rich organic molecules
...
To sustain life each organism must have a supply of
oxygen gas and an ability to release the carbon dioxide
...
As a result each organism must have a mechanism of gaseous
exchange
...

Simple organisms
Single celled organisms such as bacteria are in constant contact with their environment
...

Plants
Gaseous exchange is also very important in plants
...
In the presence of sunlight
plants photosynthesize using carbon dioxide to make simple sugars
...
At night when the rate of photosynthesis eases there will be an excess
of carbon dioxide produced
...

Plants do this by way of diffusion through pores in the leaves call the stomata
...

Less complex animals such as earthworms can survive with diffusion across the skin into their
tiny blood vessels
...
This is accomplished by
breathing
...


Mechanism Of Breathing
Inhaling
The contraction of the external intercostal muscles of the rib cage causes it to move upwards
...

These muscle contractions result in an increased space in the lungs and a reduction in
pressure of the thoracic cavity
...

Exhalation
This is the opposite of inhaling and occurs by the relaxing of the external intercostal muscles
and the relaxing of the diaphragm into a domed shape
...
Exhalation occurs because there is
more pressure in the thoracic cavity than the atmosphere, resulting in air rushing into the
lungs
...
Due to this, the transport of
food, water and minerals in plants must be efficient
...

-The xylem transports water and minerals throughout the plant
...

Sugars are carried from the source to the sink using osmotic pressure
...

It is important to note that water, minerals, and food (produced from photosynthesis) must
be transported throughout the plant otherwise the plant will wilt and/or have growth defects
...
The cells of
the root hairs have a semi-permeable membrane which allows water to enter through
osmosis
...
Since the root
hairs have a semi-permeable membrane, osmosis results in water entering the root hairs if the
concentration of water is greater in the growth medium (usually soil) than in the root hairs
...

The xylem acts as the vessels inside the plant that carries water and minerals from the root
hairs to the stem and leaves
...
Active transport is
needed because the concentration of some minerals may be greater in the root hairs than in

the growth medium
...
These minerals, once up taken by the root hairs, travel to the xylem
as solutes (dissolved particles)
...
Capillarity may be
accurately defined as the movement of a liquid up a narrow tube against the forces of
gravity due to inter-molecular forces of attraction
...
This
process is called capillarity and is due to the cohesive nature of water (ability to stick
together)
...
Water is continuously pulled up
the xylem tubes and carried up and throughout the plant
...
There is a continuous loss of water caused by transpiration
...


The Phloem
The phloem does not transport water and minerals, but food
...

Like xylem, the phloem is made of cells that are joined end to end
...
These plates have small holes
in them and these cells are called sieve tube elements
...
Next to each sieve tube element is a companion cell which

has no nucleus
...

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Transpiration
Transpiration is the loss of water from parts of the plant above the ground due to evaporation
...
Hence, it helps to cool down the plant
...

The rate of transpiration is affected by many factors such as: temperature, wind-intensity,
humidity, and light-intensity
...


Because water is constantly being taken from the top of the xylem vessels, the effective
pressure at that point is reduced
...


Factors Affecting Transpiration
Light intensity
Light intensity stimulates stomata opening
...
Photosynthesis requires gaseous exchange
and the stomata is the pore in which gaseous exchange takes place
...

Evaporation of water from the plant occurs primarily through the stomata, so as you can
understand, an increase in light intensity results in an increase in transpiration due to an
increase stomata opening
...
This is because the rate of evaporation
increases with temperature
...
If the air is dry,
then the diffusion gradient would be greater from the plant to the atmosphere
...
If

the air is humid (containing a lot of water in the atmosphere) then the opposite would be true,
and very little water would diffuse out of the atmosphere
...
Because of this, there is an increase in humidity of the air
directly surrounding the leaves
...


Water supply
If the plant has little water available, it will close its stomata
...

PIntroduction To Excretion
Excretion is the process by which metabolic waste is removed from the body of an organism
...
The unwanted metabolic waste is called excreta and
they are removed by the excretory organs
...
If the accumulation is allowed to continue, these reactions can stop
altogether
...

Waste in Animals
Waste in Plants
Carbon Dioxide
Oxygen
Urea
Carbon Dioxide
Uric Acid
Organic Salts
Water
Gums
Excess Salts
Resins
Excess Hormones
Latex
Excess Bile
Alkaloids
Excess Medicines
Calcium Oxalate
* Substances in excess, such as salts, are also created from the body
...

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Excretory Products
Carbon Dioxide
This is a by-product of respiration of both plants and animals
...
Since enzymes are pH sensitive,
the Carbon dioxide must be removed
...
In man, carbon dioxide is
transported by the blood from the cells, where it is produced
...
Here carbon dioxide diffuses from the blood into
the air sacs and leaves the body through exhalation
...
Too little or too much
water can have a negative effect on the osmotic condition in and around the cell
...
Plant cells are protected from bursting by their cell walls
...
Excess water is lost from the
surface of gaseous exchange in both plants and animals
...

Urea
This is a compound produced in mammals from the breakdown of excess amino acids
...
They are therefore converted into
a less toxic substance
...

De-amination results in the amino acid being broken down into 2 parts
...
The other part of the
broken amino acid contains ammonia and is highly toxic
...
Urea is transported by blood to the kidneys where they are excreted
...

Calcium oxalate
This is a waste material produced by plants and is stored as an insoluble crystalline structure
in the cells
...

Oxygen
Through the process of photosynthesis, oxygen is produced as a by-product
...

In plants, some waste substances are stored in parts of the plant that are dead
...
The purpose of the storage of waste material ranges from protection to
a decreased risk of being consumed
...
Plants are less complex in structure than animals, and have their own means of
excretion
...
During the day, excess oxygen gas produced
by photosynthesis is released through the stomata
...
At night, however, as photosynthesis slows, carbon
dioxide is not used up as fast as it is produced, and it is released as a waste product
...
The oxygen that is not used for
respiration is also excreted through the stomata
...
These leaves will eventually die and fall off, removing waste in the process
...

In temperate countries, such as the UK and the USA, during autumn the leaves change to a
bright array of colours
...

Have you ever noticed sticky, milky or oily substances being oozed from the bark of trees?
These are excretory products and may be resins, gums, latex and or other excretory products
...


The Kidneys
Functions of the kidney

The two main functions of the kidney are:
- Removal of metabolic waste (excretion)
- Osmoregulation, which involves regulating water and salt concentration in the blood
...

They are dark red organs shaped liked kidney beans
...
Deoxygenated blood is returned to the circulatory system from
the kidneys by the renal vein
...

Internal structure of the kidney
A kidney has several layers, as shown in the diagram below
...
Beneath this layer lies the cortex, a
smooth textured area
...
Within the
medulla are the triangular structures called pyramids, which appear striated in structure
...
These tubules drain into
the renal pelvis situated on the concave side of each kidney
...
The functional unit of the kidney is the nephron
...
The nephron starts as a small
cup-like structure known as the Bowman’s capsule and leads into what is known as the first
convoluted tubule (also known as the proximal convoluted tubule)
...

These tubules drain into the collecting duct
...
From the renal pelvis the
excretory product, urine, drains into the ureter
...


There is a branch of the renal artery, the afferent arteriole, entering the small cup-like space
of the Bowman’s capsule as a network of blood capillaries
...
Emerging from this network, the capillaries re-unite to form a small arteriole,
known as the efferent arteriole
...
The efferent arteriole divides into capillaries at several
points along the length of the tubules, absorbing various substances
...
The efferent arteriole is smaller than the
afferent arteriole
...

Some animals do not have a well developed kidney; they may have structures called
nephridia
...


Production Of Urine
The blood from the afferent arteriole, which enters the Bowman’s capsule, is rich in nutrients
such as glucose, fatty acids, amino acids, vitamins, proteins, urea and excess salts
...
Because the lumen of the afferent arteriole is significantly
smaller than the efferent arteriole there is a large amount of pressure in the glomerulus
...

Larger particles such as proteins and red blood cells do not pass through the walls of the
glomerulus and pass through to the efferent arteriole
...

Re-absorption from the Convoluted Tubules
The glomerular filtrate moves along the proximal convoluted tubule where the absorption of
most of its contents takes place
...
About 80% of the water entering the Bowman’s
capsule is absorbed into the surrounding capillaries, as well all as glucose and other nutrients
...
The remaining solution passes
along the Loop of Henle to the second convoluted tubule which joins the collecting duct
...
The reabsorbed substances are returned to the general circulation
by the renal vein
...


Previous | Next

Osmoregulation
This is the regulation of the amount of water present in the human body
...
If the body
fluids become too diluted, water will enter cells by osmosis causing them to swell or even
burst
...
This is
similar to what happens when animal cells are placed in hypotonic and hypertonic solutions
...
This process is controlled by the hormone ADH (anti-diuretic
hormone)
...

The Hypothalamus controls the secretion of ADH
...
For example, if the blood is too concentrated

(very little water), the pituitary gland releases ADH
...
As a result less water will be lost through urine
...


Introduction To Homeostasis
Homeostasis is the term used for the body’s ability to maintain a constant internal
environment
...
This constant state must be maintained in spite of changing the external
environment
...
Apart from water, which is regulated by the kidneys (the kidneys are responsible for
maintaining the levels of mineral salts as well), other substances and conditions must be kept
relatively constant such as carbon dioxide concentration, blood glucose levels, and body
temperature
...
If
carbohydrates are ingested in excess, they will be digested and the excess converted to animal
starch (also known as glycogen) by the linking of glucose molecules
...

We know what happens when carbohydrates are ingested in excess, but what happens if we
skip a meal? The first thing is we often feel a bit weak as there is a lack of sugar in the body
...


Negative Feedback
When a condition in the body changes from the norm, this information is sent to a control
center
...
This is known as negative feedback and is process by which
homeostasis takes place
...
The skin
contains many layers that aid in various processes, one such process is temperature
regulation
...
Many times the body gets too hot
or too cold
...




When the body temperature rises



Arterioles in the skin dilate, allowing increased blood flow and more loss of heat by
radiation
...
Sweat is then
evaporated from the skin causing a cooling effect due to the loss of heat from the body
...




When the body temperature falls



Arterioles in the skin contract causing less blood flow and less heat to be lost by
radiation
...
The body also generates heat through



muscular shivering
...
Many plants and animals have what
is known as an endoskeleton because it is inside the organism
...
Earthworms and insects have the two
types of skeleton respectively
...


The diagram above shows the exoskeleton on a grasshopper (insect)
...
To grip the sides of burrows, they have chaetae on their underside
...
These are thecircular muscles and
the longitudinal muscles respectively
...
So, although their skeletons are somewhat similar to the human
skeleton, the adaptations mentioned help to account for the difference
...
As a result, they have a flexible vertebral
column, a swim bladder and have fins as well as their streamlined shape
...

The limbs are connected to the main axis by girdles
...
For mammals however, the direction of
the axial skeleton is usually horizontal
...
Although
bone is hard, it contains collagen fibres which give it some amount of elasticity
...
Hence, bone contains living cells
...


Movement in the forearm

Of course we all should know that our arms can be bent at the elbow
...
This bending is known as flexing and the biceps
called flexor muscles
...
These
muscles are therefore called extensor muscles
...
When one contracts, the other relaxes
...

-Tendons join muscles to bone and are made of collagen fibres so they do not stretch

Muscles And Movement
The three types of muscle in mammals are:
1
...
Smooth- also known as involuntary muscle as the individual has no control over it
...
Striated- these muscles are attached to the bone and are also called voluntary muscles as
they are often controlled consciously
...

Note: You don’t need to be able to draw these diagrams
...
When they do this, they
allow movement to occur
...
Cardiac
muscles are the only muscles in the body that will never tire
...

In the walls of the alimentary canal, the smooth muscle operates similarly to the cardiac
muscle during peristalsis
...

The following diagram shows the relaxation and contraction of muscles

Structure And Function Of Bone
The compact bone that is seen in the diagram below is the hardest bone
...
The bone marrow is in the centre of the bone structure
...
The ends of the bone are covered
with cartilage which prevents friction between bones
...

The difference between the spongy bone and the compact bone is shown below
...


The human skeleton has several functions:
-Support: examples –leg bones, vertebral column, pelvic girdle
-Movement: examples- leg and arm bones, vertebral column
-Protection: examples- skull, ribs, vertebral column
-Making red and white blood cells- this is done by the marrow in the leg bones and the
ribs

Joints
Joints are located where two bones meet each other
...
Synovial joints- example: the shoulder joint and elbow joint
...
Ligaments hold the bones together (they stretch when the bones move)
...
Names
are given to these types of joints depending on the movement of the joint
...
(The shoulder joint is an
example)

2
...
This is where bones are
joined firmly by fibres as well as cartilage and only very slight movement (or none) can occur
...
The cartilage with fibres is known asintervertebral discs
...
Animals
The skeletons in plants are mainly for the purpose of support as plants do very little
movement
...

Growth Movements

This involves movement due to stimuli such as gravity, light, water, touch and chemicals
...

An example of growth movement is shown below
...
The
structural composition of plants and animals are built to allow different types of movements
...

 Previous | Next

Introduction To Reproduction In Plants
Reproduction may be described as the process by which an offspring (new organism) is
produced
...
Some plants may utilize both means
of reproduction depending on the circumstances
...

Asexual methods of reproduction include:
-Mitosis

-Binary fission
-Vegetative propagation
On the contrary, sexual reproduction involves gametes which must be fertilized
...
Sexual reproduction may
involve one or two plants
...
This means that it is very
unlikely for different species to fertilize each other
...

Natural means of vegetative propagation includes:
Runners/stolons: some plants produce long side shoots that develop roots, eventually
forming a new plant
...


Leaves: some plants, such as the Leaf of Life, have young plants on their leaves which will
grow into new plants if planted or when they fall off
...
They grow
sideways in the soil and have a shoot with leaves
...


Suckers: Banana is a good example of a plant that reproduces in this manner- a new stem
grows from the base of an old one, forming a new plant
...


Tuber: swollen underground stems that can develop into new plants
...
Some tubers have swollen roots which are called root tubers
...


Corm: this consists of one or more internodes with at least one growing point
...


Germination
Germination is the process by which a seed develops into a seedling
...
Some seeds may be dormant for very long periods before
they start to develop into new plants
...

*Oxygen- which is needed for respiration
...


The diagram above shows the germination of dicotyledon seeds
...
The epicotyl elongates and
forms a hook in the soil rather than growing straight up
...
Notice that the
germination is epigeal as the cotyledon does not stay below the surface of the soil
...

 Previous | Next

Seed Structure
Flowering plants may be monocotyledon or dicotyledon in nature
...
Monocotyledons have one cotyledon as
the name suggests while dicotyledons have 2
...


Structure of a red pea seed (monocotyledon)

Important parts of the seed
Testa (seed coat) – protective coat that surrounds the seed
...

Micropyle – hole through which water is absorbed for germination to occur
...
It develops into the first green leaves of
the plant
...

Plumule – develops into the new shoot of the plant
...
Animals often will eat
these fruits and in discarding the seed, aid with dispersal
...
If too many
plants of the same type are too close together, there will be too much competition for essential
substances needed by the plants
...
This means that only diffusion is needed to access the materials they require to
support life
...
It is because of this why plants
and animals have developed transport systems
...
In humans and other animals, the transport system
is made up of blood, blood vessels and a muscular pump (the heart)
...
If they are allowed to build up, they are potentially toxic
...


Blood
Blood is a rich red liquid that is transported through the body
...
Blood can be considered to be made of 2 parts, plasma and
blood cells (red and white blood cells)
...
The straw coloured liquid is called
plasma
...
Plasma accounts for approximately 55% of blood
...
Antibodies may also be found in plasma
...
The red blood cells would settle at the bottom followed by the white blood
cells and platelets, and plasma would be at the surface layer
...

Erythrocytes (Red blood cells)
These are disc shaped cells with no nucleus, and are produced in the red bone marrow by
hematopoietic cells
...
These cells are
used to transport oxygen around the body in the form of oxyhaemoglobin – Oxygen molecules
combined with the haemoglobin molecules found in the red blood cells
...
The iron readily combines with oxygen
...


Red blood cells are made very quickly as they do not live for very long (approximately 4
months)
...
Old red blood cells are
broken down in the liver, spleen and bone marrow
...


Leukocytes (White blood cells)
These are the body’s defence mechanism and are produced in the bone marrow as well as the
lymph nodes
...

How? They can ‘squeeze’ out through the walls of blood capillaries into all parts of the body
...
They are irregular in
shape and have a large nucleus which is sometimes lobed
...


Platelets
These are small cell fragments which are used in the clotting mechanism
...
It also
prevents further escape of blood
...

 Previous | Next

Functions of Blood
Since blood has several components and each of these components have a particular function,
then blood serves the collective function of all its sub-units
...

1
...

2
...
There are 3 main types of white blood cells:

Lymphocytes- These are responsible for the formation of anti-bodies
Granulocytes-These are responsible for engulfing germs
Monocytes- These have many functions such as replenishing Macrophages and response to
inflammation
...

3
...
This heat is transported through the body through blood
flow
...


Circulation In Man
Arteries take blood rich in oxygen (oxygenated blood) to the capillary network, which intern
feeds the cells in the body
...
It then goes to the lungs where gas exchange occurs so the carbon
dioxide can exit the body
...
A portal vein is a special
type of vein which links capillary networks
...
Arteries generally transport blood rich
in oxygen away from the heart, however the pulmonary artery transport deoxygenated blood
from the heart to the lungs where it is oxygenated and returned to the heart through the
pulmonary vein
...
The heart is made of a special type of muscle called the cardiac muscle
...

-Blood from the lower and upper part of the body enter the heart at the right atrium through
the posterior (also called inferior) and anterior (also called superior) vena cavarespectively
...
Oxygenated blood from the left ventricle is sent to this artery
where it then sub-divides sending blood around the entire body
...
The
two upper chambers are called the left and right atrium
...
The left and right side of the heart are separated by what is
known as a septum
...
This is because the blood from the body enters the right atrium and is sent
to the right ventricle where it is pumped to the lungs through the pulmonary artery
...
The pumping mechanism is discussed in the next section of these
notes
...
Diastole is the state of relaxation and
systole is the state of contraction
...

Blood from the lungs enter the left atrium through the pulmonary vein
...
The pace maker is ideally placed in the muscle of the right atrium
...
The excitation results in the contraction of both atria (plural for
atrium) at the same time resulting in blood rushing across the tricuspid and bicuspid valves
into the right and left ventricles
...
The wave of excitation
then reaches the ventricles which cause contraction at the same time
...


The diagram below shows the diastolic and systolic cycles

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