Human SkeletonThehuman skeletonis the internal framework of the body. It is composed of 270bonesat birth [1][2][3] this total decreases to 206 bones by adulthood after some bones have fused together. The bone mass in the skeleton reaches maximum density around age 30. The human skeleton can be divided into theaxial skeletonand the append circular skeleton. The axial skeleton is formed by thevertebral column, therib cageand theskull. The append circular skeleton, which is attached to the axial skeleton, is formed by thepectoral girdles, the pelvic girdleand the bones of the upper and lower limbs.The human skeleton serves six major functions; support, movement, protection, production ofblood cells, storage of ions and endocrine regulation.The human skeleton is not assexually dimorphicas that of many other primate species, but subtle differences between sexes in the morphologyof theskull,dentition,long bones, and pelvis exist. In general, female skeletal elements tend to be smaller and less robust than corresponding male elements within a given population. The pelvis in female skeletons is also different from that of males in order to facilitate child birth.The skeleton serves six major functions; support, movement, protection, production of blood cells, storage of minerals and endocrine regulation.The joints between bones allow movement, some allowing a wider range of movement than others, e.g. the ball and socket joint allows a greater range of movement than the pivot joint at the neck. Movement is powered by skeletal muscles, which are attached to the skeleton at various sites on bones. Muscles, bones, and joints provide the principal mechanics for movement, all coordinated by the nervous system.

Functions Of Blood Circulatory System

Blood circulates in two linked circuits: the pulmonary, which carries blood to the lungs to be oxygenated, and the systemic, which supplies oxygenated blood to the body. Arteries carrying blood from the heart divide into smaller vessels called arterioles and then into capillaries, where nutrient and waste exchange occurs. Capillaries join up to form venules, which in turn join to form veins that carry blood back to the heart. The portal vein does not return blood to the heart but carries it to the liver.In both the pulmonary and systemic circulations, the exchange of oxygen, nutrients, and waste products occurs in the capillaries that join arterioles to venules.The heart powers the pulmonary and the systemic circulations. In the pulmonary circulation, deoxygenated blood (blue) travels to the lungs, where it absorbs oxygen before returning to the heart. This oxygenated blood (red) is pumped around the body in the systemic circulation. Body tissues absorb oxygen, and deoxygenated blood returns to the heart to be pumped to the lungs again.The blood pressure in the veins is about a tenth of that in the arteries. Various physical mechanisms ensure that there is adequate venous return (blood flow back to the heart). Many deep veins lie within muscles. When the muscles contract, they squeeze the veins and force blood back to the heart. The action of inhalation during breathing also draws blood to the heart. In addition, venous return from the upper body is assisted by gravity.

Plant Support SystemA plant is any organism in the kingdom Plantae. Kingdoms are the main divisions into which scientists classify all living things onEarth. The other kingdoms are: Monera (single-celled organisms without nuclei), Protista (single-celled organisms with a nucleus), Fungi, and Animalia (animals). The scientific study of plants is called botany.A general definition of a plant is any organism that contains chlorophyll (a green pigment contained in a specialized cell called a chloroplast) and can manufacture its own food. Another characteristic of plants is that their rigid cell walls are composed mainly of cellulose, a complex carbohydrate that is insoluble (cannot be dissolved) in water. Because of the vast number of plants that exist, cellulose is the most abundant organic compound on Earth. Biologists have identified about 500,000 species of plants, although there are many undiscovered species, especially in tropical rain forests.Plant structureThose plants that produce seeds are the dominant and most studied group of plants on the planet. The leaves of these plants are all covered with a cuticle, a waxy layer that inhibits water loss. The leaves have stomata, microscopic pores, that open during the day to take in carbon dioxide and release oxygen during photosynthesis (process by which sunlight is used to form carbohydrates from carbon dioxide and water, releasing oxygen as a by-product).Plant developmentAs a plant grows, it undergoes developmental changes. Most plants continually produce new sets of organs, such as leaves, flowers, and fruits. In contrast, animals typically develop their organs only once and these organs merely increase in size as the animal grows.A plant begins its life as a seed. Various environmental cues such as sunlight, temperature changes, and the presence of nutrients signal a seed to germinate (grow). During early germination, the young seedling depends upon nutrients stored within the seed itself for growth. As the seedling grows, it begins to produce chlorophyll and turn green. Most plants become green only when exposed to sunlight because the production of chlorophyll is light-induced.meristem is a special tissue that contains actively growing and dividing cells. Apical meristems are at the tips of shoots and roots and are responsible for elongation of a plant. Lateral meristems are located along the outer sides of the stem of a plant and are responsible for thickening of the plant.Plant DiseasesPlant diseases can be infectious (transmitted from plant to plant) or noninfectious. Noninfectious diseases are usually referred to as disorders. Common plant disorders are caused by a shortage of plant nutrients, by waterlogged or polluted soil, and by polluted air. Too little (or too much) water or improper nutrition can cause plants to grow poorly. Plants can also be stressed by weather that is too hot or too cold, by too little or too much light, and by heavy winds. Pollution from automobiles and industry and the excessive use of herbicides (to kill weeds) can also cause noninfectious plant disorders.Infectious plant diseases are caused by living microorganisms that infect a plant and rob it of nutrients. Bacteria, fungi, and viruses are the living agents that cause plant diseases. None of these microorganisms are visible to the naked eye, but the diseases they cause can be detected by the symptoms of wilting, yellowing, stunting, and abnormal growth patterns.Some plant diseases are caused by rod-shaped bacteria. The bacteria enter the plant through natural openings, like the stomata of the leaves, or through wounds in the plant tissue. Once inside, the bacteria plug up the plant's vascular system and cause the plant to wilt. Other common symptoms of bacterial disease include rotting and swollen plant tissues. Bacteria can be spread by water, insects, infected soil, or contaminated tools.About 80 percent of plant diseases can be traced to fungi, which can grow on living or dead plant tissue. They can penetrate plant tissue or grow on the plant's surface. Fungal spores, which act like seeds, are spread by wind, water, soil, and animals to other plants. Warm, humid conditions promote fungal growth.Viruses are the hardest pathogens (disease-causing organisms) to control. Destroying the infected plants to prevent spreading to healthy plants is usually the best control method. While more than 300 plant viruses have been identified, new strains continually appear because these organisms are capable of mutating (changing their genetic makeup). Viruses are spread by contaminated seeds and sucking insects (aphids, leafhoppers, trips) that act as carriers of the virus. The symptoms of viral infection include yellowing, stunted growth in some part of the plant. Leaf rolls and narrow leaf growth are other indications of viral infection. The mosaic viruses can infect many plants. Plants infected with this virus have mottled or streaked leaves.

Cardiovascular diseaseCardiovascular disease(also calledheart disease) is a class of diseases that involve theheart, theblood vessels(arteries,capillaries, andveins) or both. Cardiovascular disease refers to any disease that affects thecardiovascular system, principally cardiac disease, vascular diseases of the brain andkidney, andperipheral arterial disease.The causes of cardiovascular disease are diverse butatherosclerosisand/orhypertensionare the most common. In addition, with aging come a number ofphysiologicaland morphological changes that alter cardiovascular function and lead to increased risk of cardiovascular disease, even in healthy asymptomatic individuals. Cardiovascular disease is the leading cause of deaths worldwide, though, since the 1970s, cardiovascular mortality rates have declined in manyhigh-income countries.At the same time, cardiovascular deaths and disease have increased at a fast rate in low- and middle-income countries.Although cardiovascular disease usually affects older adults, the antecedents of cardiovascular disease, notably atherosclerosis, begin in early life, making primary prevention efforts necessary from childhood.There is therefore increased emphasis on preventing atherosclerosis by modifying risk factors, such ashealthy eating,exercise, and avoidance ofsmoking tobacco.Evidence suggests a number of risk factors for heart diseases: age, gender, high blood pressure, hyperlipidemia, diabetes mellitus, tobacco smoking, excessive alcohol consumption, sugar consumption,family history,obesity, lack of physical activity, psychosocial factors, andair pollution. While the individual contribution of each risk factor varies between different communities or ethnic groups the consistency of the overall contribution of these risk factors to epidemiological studies is remarkably strong. Some of these risk factors, such as age, gender or family history, are immutable; however, many important cardiovascular risk factors are modifiable by lifestyle change, social change, drug treatment and prevention of Serrano's Cardiac Triad: hypertension, hyperlipidemia, and diabetes.Age is by far the most important risk factor in developing cardiovascular or heart diseases, with approximately a tripling of risk with each decade of life.It is estimated that 82 percent of people who die of coronary heart disease are 65 and older.At the same time, the risk of stroke doubles every decade after age 55. Multiple explanations have been proposed to explain why age increases the risk of cardiovascular/heart diseases. One of them is related to serum cholesterol level. In most populations, the serum total cholesterol level increases as age increases. In men, this increase levels off around age 45 to 50 years. In women, the increase continues sharply until age 60 to 65 years.

Type of Blood GroupsAblood type(also called ablood group) is a classification ofbloodbased on the presence or absence ofinheritedantigenicsubstances on the surface ofred blood cells(RBCs). These antigens may beproteins,carbohydrates,glycoproteins, orglycolipids, depending on the blood group system. Some of these antigens are also present on the surface of other types ofcellsof varioustissues. Several of these red blood cell surface antigens can stem from oneallele(or very closely linkedgenes) and collectively form a blood group system.Blood types areinheritedand represent contributions from both parents. A total of 32human blood group systemsare now recognized by theInternational Society of Blood Transfusion(ISBT). The two most important ones areABOand theRhD antigen; they determine someone's blood type (A, B, AB and O, with + and - denoting RhD status).Manypregnantwomen carry afetuswith a blood type different from their own, and the mother can formantibodiesagainst fetal RBCs. Sometimes these maternal antibodies are a small immunoglobulin, which can cross the placenta and causehemolysisof fetal RBCs, which in turn can lead tohemolytic disease of the newborncalled erythroblastosis fetalis, an illness oflow fetal blood countsthat ranges from mild to severe. Sometimes this is lethal for the fetus; in these cases it is calledhydrops fetalis. Ablood type(also called ablood group) is a classification ofbloodbased on the presence or absence ofinheritedantigenicsubstances on the surface ofred blood cells(RBCs). These antigens may beproteins,carbohydrates,glycoproteins, orglycolipids, depending on the blood group system. Some of these antigens are also present on the surface of other types ofcellsof varioustissues. Several of these red blood cell surface antigens can stem from oneallele(or very closely linkedgenes) and collectively form a blood group system.Blood types areinheritedand represent contributions from both parents. A total of 32human blood group systemsare now recognized by theInternational Society of Blood Transfusion(ISBT).The two most important ones areABOand theRhD antigen; they determine someone's blood type (A, B, AB and O, with + and - denoting RhD status).Manypregnantwomen carry afetuswith a blood type different from their own, and the mother can formantibodiesagainst fetal RBCs. Sometimes these maternal antibodies areIgG, a small immunoglobulin, which can cross the placenta and cause hemolysisof fetal RBCs, which in turn can lead tohemolytic disease of the newborncalled erythroblastos is fetalis, an illness oflow fetal blood countsthat ranges from mild to severe. Sometimes this is lethal for the fetus; in these cases it is called hydrops fetalis.

Down SyndromeDown syndrome is a chromosomal condition that is associated with intellectual disability, a characteristic facial appearance, and weak muscle tone (hypotonia) in infancy. All affected individuals experience cognitive delays, but the intellectual disability is usually mild to moderate.People with Down syndrome may have a variety of birth defects. About half of all affected children are born with a heart defect. Digestive abnormalities, such as a blockage of the intestine, are less common.Individuals with Down syndrome have an increased risk of developing several medical conditions. These include gastroesophageal reflux, which is a backflow of acidic stomach contents into the esophagus, and celiac disease, which is an intolerance of a wheat protein called gluten. About 15 percent of people with Down syndrome have an underactive thyroid gland (hypothyroidism). The thyroid gland is a butterfly-shaped organ in the lower neck that produces hormones. Individuals with Down syndrome also have an increased risk of hearing and vision problems. Additionally, a small percentage of children with Down syndrome develop cancer of blood-forming cells (leukemia).Delayed development and behavioral problems are often reported in children with Down syndrome. Affected individuals' speech and language develop later and more slowly than in children without Down syndrome, and affected individuals' speech may be more difficult to understand. Behavioral issues can include attention problems, obsessive/compulsive behavior, and stubbornness or tantrums. A small percentage of people with Down syndrome are also diagnosed with developmental conditions called autism spectrum disorders, which affect communication and social interaction.People with Down syndrome often experience a gradual decline in thinking ability (cognition) as they age, usually starting around age 50. Down syndrome is also associated with an increased risk of developing Alzheimer disease, a brain disorder that results in a gradual loss of memory, judgment, and ability to function. Approximately half of adults with Down syndrome develop Alzheimer disease. Although Alzheimer disease is usually a disorder that occurs in older adults, people with Down syndrome usually develop this condition in their fifties or sixties.

Genetic EngineeringGenetic engineering, also calledgenetic modification, is the direct manipulation of an organism'sgenomeusingbiotechnology. NewDNAmay be inserted in the host genome by first isolating and copying the genetic material of interest usingmolecular cloningmethods to generate a DNA sequence, or by synthesizing the DNA, and then inserting this construct into the host organism.Genesmay be removed, or "knocked out", using anuclease.Gene targetingis a different technique that useshomologous recombinationto change an endogenous gene, and can be used to delete a gene, removeexons, add a gene, or introducepoint mutations.An organism that is generated through genetic engineering is considered to be agenetically modified organism(GMO). The first GMOs were bacteria in 1973 and GM mice were generated in 1974.Insulin-producing bacteria were commercialized in 1982 and genetically modified food has been sold since 1994.Glofish, the first GMO designed as a pet, was first sold in the United States December in 2003.Genetic engineering techniques have been applied in numerous fields including research, agriculture, industrial biotechnology, and medicine. Enzymes used in laundry detergent and medicines such as insulin and human growth hormone are now manufactured in GM cells, experimental GM cell lines and GM animals such as mice orzebrafishare being used for research purposes, andgenetically modified cropshave been commercialized.Plants, animals or micro organisms that have changed through genetic engineering are termed genetically modified organisms or GMOs.Bacteria were the first organisms to be genetically modified. Plasmid DNA containing new genes can be inserted into the bacterial cell and the bacteria will then express those genes. These genes can code for medicines or enzymes that process food and othersubstrates.[17][18]Plants have been modified for insect protection, herbicide resistance, virus resistance, enhanced nutrition, tolerance to environmental pressures and the production of edible vaccines.Most commercialised GMO's are insect resistant and/or herbicide tolerant crop plants.[20]Genetically modified animals have been used for research, model animals and the production of agricultural or pharmaceutical products. They include animals withgenes knocked out,increased susceptibility to disease, hormones for extra growth and the ability to express proteins in their milk.

Genetic engineering is also being used to createBioArt.Some bacteria have been genetically engineered to create black and white photographs. Genetic engineering has also been used to create novelty items such as lavender-coloredcarnations,blue roses, andglowing fish.