CONNECTIVE TISSUES

Connective tissues are the supporting tissues of the body and hold parts of the body together. They originate from the mesoderm layer of the embryo, contain large amounts of intercellular material or matrix. The matrix is normally secreted by the connective tissue cells, and form the bulk of the tissue.

The connective tissues comprise the fibrous and elastic connective tissue, the adipose (fatty) tissues and skeletal (cartilage and bone) tissues.

i. Fibrous tissues, found throughout the body, connect to one another by an irregular network of strands, forming a soft, cushiony layer that also supports blood vessels, nerves and other organs
ii. Elastic tissues, found in ligaments, the trachea, and arterial walls, stretches and contracts again with each pulse beat
iii. Adipose tissues, contain and store fat
iv. cartilage, differs from bone as it is not so hard and can be flexible but of high tensile strength
· Cartilage is produced by chondrocytes that secrete the protein matrix called chondrin with no calcium carbonate
· Chondrocytes are also found in lacunae but there is no canaliculus. They can receive oxygen and nutrients through diffusion
· Cartilage is divided into three types : hyaline, elastic and fibrous depending on the types of proteins in the matrix
· The examples is hyaline cartilage found in the entire skeleton of the embryo, and rings of trachea. The U-shape rings prevent the trachea from collapsing for easy air passage. In adults, hyaline cartilage is restricted to the surfaces of bones at joints, the flexible connections between sternum and ribs
· Matrix of the hyaline cartilage consist of glycoprotein and collagen fibrils that make it looks translucent
· Elastic cartilage occurs in the pinna of the outer ear and the epiglottis
· Some cartilage contains collagen fibres, which give substantial additional strength and rigidity. This fibro-cartilage occurs in the invertebral disc of spinal column

Note:
Bone is a very strong and rigid tissue, make up the greater part of the skeleton in many vertebrates, and approximately 15% of the body mass of an adult mammal. Chemically, it is composed of approximately 70% mineral and 30% organic matter


v. Bone
· Bone is formed from osteocytes that secrete the matrix of calcium phosphate (85%), calcium carbonate (10%), together with magnesium, calcium fluorides (5%) and proteins
· There are two types of bone tissue; compact bone and spongy bone

Compact Bone
· Compact bone consists of Haversian systems of cylindrical shape with a haversian canal in the centre. Each cylinder consist of concentric rings of osteocytes and the calcified matrix.
· The Haversian canal is supplied with blood vessels that bring raw materials for the construction of the bone or it can be reversed as in osteoporosis
· The Haversian canals are linked by a Volkmann canal forming an inter-connecting system for the blood circulation
· The osteocytes are found in small spaces called lacunae with intricate tiny canaliculi (singular canaliculus) for distributing the matrix during bone formation. Canaliculi are the routes by which nutrients, waste materials and respiratory gases move between blood plasma and bone cells.

Spongy Bone
· It occurs within larger bones and always surrounded by compact bone, consist of thin sheets of bone called trabeculae
· Trabeculae contain osteocytes, which are more or less irregularly dispersed in the matrix.
· The matrix contains a rather smaller proportion of inorganic material than does of compact bone
· The spaces within the spongy bone at the head of the long bones contain red bone marrow tissue. This very soft tissue is less dense and is the site of red blood cell formation.
· Yellow marrow tissue, consisting principally of fat, fills the spaces within the spongy bone of the shaft

Note:

Most bones of the body are formed by ossification (the aying down of the inorganic components of bone) of pre-existing cartiage by the bone forming cells called osteoblast.
Examples of bones of cartilaginous origin are the limbs, girdles, and vertebral column. The bones of the skull and the clavicles (collar bones) are not formed by the ossification of cartilage. These bones, called dermal or membrane bones, are formed by direct ossification of the dermis skin.

i. Blood
Blood is a fluid connective tissue contained within a closed system of tubes (arteries, veins and capillaries). Blood cells are divided into erythrocytes (red blood cells), leucocytes (white blood cells) and platelets (thrombocytes).

· Erythrocytes
- It is formed in the bone marrow, though the liver can form it in the fetus
- It has nucleus before matures, and digested later to enable more haemoglobin to be filed for carrying oxygen
- Its membrane is very thin enabling easy gaseous exchange i.e oxygen and carbon dioxide to go in or out
- Its shape is biconcave so that its surface to volume ratio is increased for gaseous exchange too
· Leukocytes, are short-lived cells and divided into granulocytes and agranulocytes
Granulocytes
- have granules in their cytoplasm and they are formed in the bone marrow and matured there
- are divided into three types (Neutrophils, eosinophils, basophils) depending on pH of dye that can stain it
Agranulocytes
- do not have granules in their cytoplasm and are formed in the bone marrow but may mature in the thymus gland
- are divided into monocytes and lymphocytes
- Lymphocytes are divided into lymphocyte T, which mature in thymus gland and lymphocyte B, which mature in bone marrow> lymphocyte B produces antibody
· Platelets, are cell fragments produced by large cells in the bone marrow
- They are disc-shape and very small (only 2 mm in diameter)
- They are have an important role in the process of blood clotting

Note:
Blood makes up 6-10 % of the body mass in mammals. The fluid matrix of blood is caed plasma. Plasma makes up 55% of the blood by volume, surrounded by blood cells. Each cubic millimeter of blood contains about five million erythrocytes with the lifespan of an erythrocyte is about 120 days. There are relatively few leucocytes in the blood; about one leucocyte for every 700 erythrocytes and there are between 150 000 and 400 000 platetelets in each cubic millimetre of blood.

Nervous tissues

NERVOUS TISSUES
Nervous tissue is made up of cells known as neurons, which are adapted for the transmission of electrical impulses, together with associated neuroglia cells.
i. Commonly, all neurons have three things in structure
· a cell body, containing a nucleus. Surrounded by a plasma membrane, has a lot of mitochondria, golgi apparatus, endoplasmic reticulum, ribosomes but no centriole
· a dendron, Nerve fibres take/transmit impulses towards the cell body. The terminal branches of dendron are called dendrites
· an axon, a single fibre takes impulses away from the cell body
Neuroglia cells, are ten times more numerous than neurons, are found through out the Central Nervous System. Neuroglia mechanically support the neurons, supply the nourishment to neurone fibres, removed wastes from neurons, guiding axon migration and provide immune functions. Some are involved in the memory process by storing information in the form of RNA.

ii. Three types of neurons
· Afferent/Sensory /Receptor neurons, transmits impulses from receptor organ to the Central Nervous System
· Efferent/Motor neurons, transmits impulse from the Central Nervous System to effector i.e muscles or glands
· Interneurone (associative/relay/intermediate neurons), receives impulses from sensory neurons and transmits it to the motor neurons. It is found in the brain or spinal cord. Some can generate impulse and other transmits impulse from one to the other. It has varies shapes, bipolar and multipolar with one or more dendrons or axons.

Epithelial tissue

Animal tissues take their first form when the blastula cells arising from the fertilized ovum, differentiate into three germ layers: the ectoderm, mesoderm, and endoderm. Through further cell differentiation or histogenesis, group of cells grow into more specialized units to form organs.
Animal cells are classified into four types based on fundamental tissues i.e epithelial, nervous, muscular and connective tissues.

EPITHELIAL TISSUES
They are divided into covering and glandular epithelia.

a. Covering Epithelia
i. Their structural features are as follows
· Epithelial cells generally have large nuclei, clear outlines, and a large amount of of granular protoplasm
· Their cells are attached to the underlying tissues by a basement membrane, made a network of white, wavy, non-elastic collagen fibres
· The junctions between epithelial cells tend to be strongly held together by desmosomes
· Epithelial tissue consisting of one or a few layers of cells, is found on the internal and external surfaces of organs
ii. Their functions are as follows
· protect the underlying tissues against mechanical injury
· protect against water loss and dehydration, infection of microorganisms and also radiant energy
· are involved in the physiological processes that take place across surfaces including respiratory gas exchange, excretion, elimination of waste and absorption
· Some of the modify to form special receptors for stimuli
iii. There are classified into two ways
Based on arrangement of cells,
· Simple epithelium, arranged in one/single layer
· Stratified/Compound epithelium, arranged in more than one layer
· Pseudo-stratified epithelium, Cells look like arranged in layers but every one is attached to the basement membrane
Based on their cell shapes,
· Squamous epithelium, Cells are flattened like scales or tiles
· Cuboidal epithelium, Cells more or less like cubes
· Columnar epithelium, Cells look like pillars, height is longer than their base
· Transitional epithelium, Cells can change shape when stretched
iv. There are eight types of covering epithelia
· Simple --à squamous ep. Is found in the outer layer of Bowman capsule,
endothelium of blood vessels and alveolar walls
--à cuboidal ep. Is found in the collecting ducts and tubules of
nephron
--à columnar ep. Is found in lining the innermost layer of intestine
and stomach
· Stratified --à squamous ep. Is found in the epidermis of skin and lining the
innermost layer of oesophagus
--à cuboidal ep. is found in the excretory ducts of sweat gland
--à columnar ep. Is found in the secretory ducts of the mammary
glands
· Pseudo stratified epithelium,is found in the innermost layer of trachea, bronchi and bronchioles
· Transitional epithelium, is found in the wall of urinary bladder

b. Glandular Epithelia
i. Glandular epithelia are gland cells derived from epithelia and can secrete liquid containing mucus, hormone or enzymes
ii. There are two types of glandular epithelia i.e exocrine glands and endocrine glands
iii. Exocrine glands
· they have ducts that secrete substances out
· there are little capillaries in them
· they produce liquid with proteins or enzymes
· their formation is by invagination of epithelia
iv. Endocrine glands
· they have no duct and the secretion is directly emptied into the blood capillaries around them
· a lot of capillaries are found within
· they produce hormones
· their formation is by detachment from epithelia as shown below
· examples are thyroid and adrenal gland

------------------------------------------------------------------------------------------------------------------------------------------------------------------

Clegg, C. J. and D. G. Mackean, 1994, Advanced Biology, Principles and Application, John Murray Pub.
Encarta
Kooi, Foo Yuen, 2003, STPM Biology, Volume 1, Penerbitan Pelangi SDN. BHD. Malaysia
Kwan, Lam Peng and Eric Y. K. Lam, Federal Publications, An Imprint of Times Media, Singapore

Ibn al-Baitar

Abu Muhammad Abdallah Ibn Ahmad Ibn al-Baitar Dhiya al-Din al-Malaqi (Arabic: ابن البيطار‎) (died 1248) was an Arab scientist, botanist, pharmacist and physician. He is considered one of the greatest scientists of Al-Andalus and is believed to be one of the greatest botanists and pharmacists of the Islamic Golden Age and Muslim Agricultural Revolution.

Born in the Andalusian city of Málaga at the end of the 12th century, he learned botany from the Málagan botanist Abu al-Abbas al-Nabati with whom he started collecting plants in and around Spain. Al-Nabati was responsible for developing an early scientific method, introducing empirical and experimental techniques in the testing, description and identification of numerous materia medica, and separating unverified reports from those supported by actual tests and observations. Such an approach was thus adopted by Ibn al-Baitar.^[1]

In 1219, Ibn al-Baitar left Málaga to travel in the Islamic world to collect plants. He travelled from the northern coast of Africa as far as Anatolia. The major stations he visited include Bugia, Constantinople, Tunis, Tripoli, Barqa and Adalia.

After 1224, he entered the service of al-Kamil, an Ayyubid Sultan, and was appointed chief herbalist. In 1227 al-Kamil extended his domination to Damascus, and Ibn al-Baitar accompanied him there which provided him an opportunity to collect plants in Syria. His researches on plants extended over a vast area including Arabia and Palestine. He died in Damascus in 1248.

------------------------------------------------------------------------------------------

Source : http://en.wikipedia.org/wiki/Ibn_al-Baitar

James D. Watson

James Dewey Watson (born April 6, 1928) is an American molecular biologist, best known as one of the co-discoverers of the structure of DNA. Watson, Francis Crick, and Maurice Wilkins were awarded the 1962 Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material".^[3] He studied at the University of Chicago and Indiana University and subsequently worked at the University of Cambridge's Cavendish Laboratory in England where he first met his future collaborator and personal friend Francis Crick.

In 1956 he became a junior member of Harvard University's Biological Laboratories until 1976, but in 1968 served as Director of Cold Spring Harbor Laboratory on Long Island, New York and shifted its research emphasis to the study of cancer. In 1994 he became its President for ten years, and then subsequently served as its Chancellor until 2007, when he was forced into retirement by controversy over several comments about race and intelligence. Between 1988 and 1992 he was associated with the National Institutes of Health, helping to establish the Human Genome Project. He has written many science books, including the seminal textbook The Molecular Biology of the Gene (1965) and his bestselling book The Double Helix (1968) about the DNA Structure discovery.

----------------------------------------------------------------------------------

Source : http://en.wikipedia.org/wiki/James_D_Watson

History of cell

The cell was first discovered by Robert Hooke in 1665. He examined very thin slices of cork and saw billions of tiny pores that he remarked looked like the walled compartments of a honeycomb. Because of this association, Hooke called them cells, the name they still bear. However, Hooke did not know their real structure or function. ^[1] Hooke's description of these cells (which were actually non-living cell walls) was published in Micrographia.^[2]. His cell observations gave no indication of the nucleus and other organelles found in most living cells.

The first man to witness a live cell under a microscope was Antonie van Leeuwenhoek, who in 1674 described the algae Spirogyra and named the moving organisms animalcules, meaning "little animals".^[3]. Leeuwenhoek probably also saw bacteria.^[4] Cell theory was in contrast to the vitalism theories that had been proposed before the discovery of cells.

The idea that cells were separable into individual units was proposed by Ludolph Christian Treviranus^[5] and Johann Jacob Paul Moldenhawer^[6]. All of this finally led to Henri Dutrochet formulating one of the fundamental tenets of modern cell theory by declaring that "The cell is the fundamental element of organization"^[7]

The observations of Hooke, Leeuwenhoek, Schleiden, Schwann, Virchow, and others led to the development of the cell theory. The cell theory is a widely accepted explanation of the relationship between cells and living things. The cell theory states:

1. All living things are composed of one or more cells.
2. The cell is the most basic unit of life.
3. All cells come from pre-existing cells.

The cell theory holds true for all living things, no matter how big or small, or how simple or complex. Since according to research, cells are common to all living things, they can provide information about all life. And because all cells come from other cells, scientists can study cells to learn about growth, reproduction, and all other functions that living things perform. By learning about cells and how they function, you can learn about all types of living things.

Credit for developing cell theory is usually given to three scientists: Theodor Schwann, Matthias Jakob Schleiden, and Rudolf Virchow. In 1839, Schwann and Schleiden suggested that cells were the basic unit of life. Their theory accepted the first two tenets of modern cell theory (see next section, below). However the cell theory of Schleiden differed from modern cell theory in that it proposed a method of spontaneous crystallization that he called "Free Cell Formation"^[8]. In 1858, Rudolf Virchow concluded that all cells come from pre-existing cells, thus completing the classical cell theory.

[edit] Classical interpretation

1. All organisms are made up of one or more cells.
2. Cells are the fundamental functional and structural unit of life.
3. All cells come from pre-existing cells.
4. The cell is the unit of structure, physiology, and organization in living things.
5. The cell retains a dual existence as a distinct entity and a building block in the construction of organisms.

[edit] Modern interpretation

The generally accepted parts of modern cell theory include:

1. The cell is the fundamental unit of structure and function in living things.
2. All cells come from pre-existing cells by division.
3. Energy flow (metabolism and biochemistry) occurs within cells.
4. Cells contain hereditary information (DNA) which is passed from cell to cell during cell division
5. All cells are basically the same in chemical composition.
6. All known living things are made up of cells.
7. Some organisms are unicellular, i.e., made up of only one cell.
8. Others are multicellular, composed of a number of cells.
9. The activity of an organism depends on the total activity of independent cells

------------------------------------------------------------------------------------------


Source : http://en.wikipedia.org/wiki/Cell_theory

Biology

Biology (from Greek βιολογία - βίος, bios, "life"; -λογία, -logia, study of) is the science that studies living organisms. Prior to the nineteenth century biology came under the general study of all natural objects called natural history. The term biology was first coined by Gottfried Reinhold Treviranus . It is now a standard subject of instruction at schools and universities around the world, and over a million papers are published annually in a wide array of biology and medicine

Biology examines the structure, function, growth, origin, evolution, distribution and classification of all living things. Five unifying principles form the foundation of modern biology: cell theory, evolution, gene theory, energy, and homeostasis.^[2]

Traditionally, the specialized disciplines of biology are grouped by the type of organism being studied: botany, the study of plants; zoology, the study of animals; and microbiology, the study of microorganisms. These fields are further divided based on the scale at which organisms are studied and the methods used to study them: biochemistry examines the fundamental chemistry of life, molecular biology studies the complex interactions of systems of biological molecules, cellular biology examines the basic building block of all life, the cell; physiology examines the physical and chemical functions of the tissues and organ systems of an organism; and ecology examines how various organisms interrelate with their environment.

----------------------------------------------------

source : http://en.wikipedia.org/wiki/Biology

Swine Flu Prevention

There is a lot of anxiety among our society concerning the Swine Flu. It wouldn't be my personal preference to catch the illness because it seems to give a hard swift punishment to the victim. This strain can carry morph into any one of the three strains of influenza. Pigs do carry influenza viruses and can adapt or morph in humans. The swine flu can also change to infect birds, causing the strain to switch genes and create a pandemic.

Like any type of new illness there are precautions people can take to prevent infection and the spread of the Swine Flu. It natural for people to cough directly into their hands. All the germs coming from the reparatory system are transported from the internal body and passed along to places, like car keys, door knobs, drinking fountains, and door handles. This can devastate the main population if one is carrying the actual Swine Flu. Create a habit of coughing into your shoulder or into your arm to minimize the spread of all germs and not just the Swine Flu.

At night it would be favorable to spray Lysol spray on light switches, toilet seats, toilet handles, freezer and fridge handles to kill the Swine flu and other bacteria. Lysol is a powerful deterrent to assist in the spread of germs, and illness. Pump bottles of hand sanitizer will help kill the germs on the surface of the skin and can assist in preventing the spread of the Swine flu. But there is a more advanced and preferred method to preventing the spread of Swine Flu.

We have been taught from an early age to wash our hands. Many take for granted the hand washing philosophy. The truth is that Lysol, hand sanitizer, coughing into the arm are all good ways but a good solid deep hand wash is the number one method for preventing the spread of germs. Hand sanitizer, and Lysol only kill the surface of where these items are applied. A deep hand wash bypasses the surface of the skin and really digs down to the grooves and pits of the hand. Ridges within the hand can be microscopic and hard to get reach for the Lysol, and hand sanitizer. A good hefty dose of liquid soap will grind down to the microscopic ridges and pours in the hand and do real damage to destroy the Swine Flu.

------------------------------------------------------------------

About the Author:

You can learn more about your health on Nathans Health Website http://www.poundinghearts.com

Ezine Articles

Article Source: ArticlesBase.com - Swine Flu Prevention

What is Swine Flu?

Swine flu or swine influenza is a disease common in swine, with normal flu-like symptoms, but caused by any strain of the swine influenza virus (SIV - virus endemic in pigs). Though rare in humans, individuals with greater exposure to swine could contract swine influenza if the swine are carrying the particular rare strain of the SIV that is capable of affecting humans. Even then, it is a rare occurrence for the strain to be able to pass from human to human. This could occur if the SIV is able to mutate into a form that can be easily transmitted among humans.

The swine flu outbreak of 2009 is believed to be caused by such a mutated strain of the SIV. The current outbreak is called swine flu only because one of the surface proteins of the tested virus is similar to the one which infects pigs. It is still unknown if this is currently infecting pigs though it’s clearly spreading among people, leading the World Health Organization to raise the Phase 4 pandemic alert. This new strain responsible for the outbreak has been found to be a re-assortment of strains of the influenza A virus subtype H1N1. These strains are separately endemic in humans and in swine.

According to the Centers for Disease Control and Prevention (CDC), Tamiflu (oseltamivir) and Relenza (zanamivir) would help in treatment and prevention. Antiviral drugs, if started within two days of the manifestation of symptoms, succeed in reducing the severity of the symptoms, preventing further complications, and hastening cure. The most effective method of prevention is to wash hands frequently with soap or with a foam or alcohol-based gel hand wash that helps wipe away bacteria and viruses. Vaccines against the 2009 H1N1 strain outbreak are in the development stage and are expected to be ready by June 2009.

------------------------

About the Author:

Reliable Paper offers an extensive line of disinfectants, spray and wipes that will help alleviate the spread of swine flu!

Article Source: ArticlesBase.com - What is Swine Flu?

Eukaryotic cells

Eukaryotic cells are about 10 times the size of a typical prokaryote and can be as much as 1000 times greater in volume. The major difference between prokaryotes and eukaryotes is that eukaryotic cells contain membrane-bound compartments in which specific metabolic activities take place. Most important among these is the presence of a cell nucleus, a membrane-delineated compartment that houses the eukaryotic cell's DNA. It is this nucleus that gives the eukaryote its name, which means "true nucleus." Other differences include:

• The plasma membrane resembles that of prokaryotes in function, with minor differences in the setup. Cell walls may or may not be present.
• The eukaryotic DNA is organized in one or more linear molecules, called chromosomes, which are associated with histone proteins. All chromosomal DNA is stored in the cell nucleus, separated from the cytoplasm by a membrane. Some eukaryotic organelles such as mitochondria also contain some DNA.
• Eukaryotes can move using cilia or flagella. The flagella are more complex than those of prokaryotes.

------------------------------------
adopted from: http://en.wikipedia.org/wiki/Cell_(biology)

Biology

Life is so worth!
so start study biology
no matter who you are
no matter what you do ...