ENVIRONMENT EPIDEMIOLOGY

                                                          Amirul-skeletal-unisel.jpeg



DEFINE EPIDEMIOLOGY                                                             

Epidemiology is the science that studies the patterns, causes, and effects of health and disease conditions in defined populations. It is the cornerstone of public health, and informs policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare

FUNCTION OF EPIDEMIOLOGY

 Epidemiologists help with study design, collection, and statistical analysis of data, and interpretation and dissemination of results (including peer review and occasional systematic review). Epidemiology has helped develop methodology used in clinical research, public health studies, and, to a lesser extent, basic research in the biological sciences.

Major areas of epidemiological study includedisease etiology, transmission,outbreak investigation, 
disease surveillance and screening, biomonitoring, and comparisons of treatment effects such as in clinical trials. Epidemiologists rely on other scientific disciplines like biology to better understand disease processes, statistics to make efficient use of the data and draw appropriate conclusions, social sciences to understand proximate and distal causes better, and engineering for exposure assessment.

JOHN SNOW & EPIDEMIOLOGY

-John Snow is famous for his investigations into the causes of the 19th century cholera epidemics, and is also known as the father of (modern) epidemiology.He began with noticing the significantly higher death rates in two areas supplied by Southwark Company. His identification of the Broad Street pump as the cause of the Soho epidemic is considered the classic example of epidemiology. Snow used chlorine in an attempt to clean the water and removed the handle. Other pioneers include Danish physician Peter Anton Schleisner, who in 1849 related his work on the prevention of the epidemic of neonatal tetanus on the Vestmanna Islands in Iceland. Another important pioneer was Hungarian physician Ignaz Semmelweis, who in 1847 brought down infant mortality at a Vienna hospital by instituting a disinfection procedure. Disinfection did not become widely practiced until British surgeon Joseph Lister 'discovered' antiseptics in 1865 in light of the work of Louis Pasteur.

-Another breakthrough was the 1954 publication of the results of a British Doctors Study, led by Richad Doll and Austin Bradford Hill, which lent very strong statistical support to the suspicion that tobacco smoking was linked to lung cancer.

In the late 20th century, with advancement of biomedical sciences, a number of molecular markers in blood, other biospecimens and environment were identified as predictors of development or risk of a certain disease. Epidemiology research to examine the relationship between these biomarkers analyzed at the molecular level and disease was broadly named “molecular epideiologym”..While most molecular epidemiology studies are still using conventional disease diagnosis and classification systems, it is increasingly recognized that diseaseluti evoon represents inherently heterogeneous processes differing from person to person.
 Studies to examine the relationship between an exposure and molecular pathologic signature of disease (particularly cancer) became increasingly common throughout the 2000s. However, the use of molecular pathology in epidemiology posed unique challenges including lack of research guidelines and standardized statistical methodologies, and paucity of interdisciplinary experts and training programs. To resolve these issues and advance population health science in the era of moleculare, precision medicine “ prmoleculaathology” and “epidemiology” was integrated to create a new interdisciplinary field of “molecular pathological epidemiology” (MPE), defined as “epidemiology of molecular pathology and heterogeneity of disease.

SOURCE;;http://en.wikipedia.org/wiki/Epidemiology#cite_note-25

http://www.dugdug.com/wp-content/uploads/2013/10/8-epidemiology.jpg

FUNCTION OF THE INTEGUMENTARY SYSTEM

                                       

                                          Amirul-skeletal-unisel.jpeg

The integumentary system (skin) has been called a membrane and an organ but, it is generally considered a system because it has organs that work together as a system. It is sometimes considered an organ because it contains several types of tissues and a membrane and it covers the body. 

    

The skin is the largest organ of the body and includes associated organs and derivatives of the skin such as hair, nails, glands, and specialized nerve endings. One square centimeter of skin contains approximately 70 cm of blood vessels, over 100 glands, and well over 200 sensory receptors!  For this reason, it is virtually impossible to find an area of the skin that is insensitive to sensations of touch, pressure, heat, cold, pain, or vibration.

   

 Skin serves the primary function of protection. It also cushions internal organs and serves as the first line of defense from infection and injury. It is waterproof, stretchable, and capable of repairing itself. 

    

Three main layers make up the skin:

1. Epidermis: the outer layer of skin. It is made up of 5-6 layers with no blood vessels. The layers (outer to innermost) are the stratum corneum, stratum granulosum, stratum spinosum, and the stratum germinativum which replaces the outer layers with new cells. The stratum lucidum is found primarily in the palms of the hands and the soles of the feet. It adds additional thickness to the skin where greater friction typically occurs.

2. Dermis: also called corium or "true skin". The dermis contains elastic connective tissue, blood vessels, involuntary muscle, sweat and oil glands, and hair follicles. The dermis consists of two principal portions. The more superficial portion consists of areolar connective tissue with many fine elastic fibers.  Papillae cover the top of the dermis which fit into ridges on the stratum germinativum. These ridges form lines (fingerprints or footprints) on the skin which is unique to each individual. This region is called the papillary region. The deeper portion of the dermis is the region which consists of dense, irregular connective tissue intertwined with course elastic fibers.

3. Hypodermis: also called subcutaneous fascia. It is the innermost layer and is made up of loose, connective tissues like areolar and adipose (fatty) tissue. About half the body's supply of adipose tissue is found in the subcutaneous fat. It is an excellent insulator and shock absorber, and anchors the skin to the organs below.

    

The integumentary system has two main types of glands: sudoriferous (sweat) glands and sebaceous (oil) glands. 

   

 The principal types of sudoriferous glands are eccrine, apocrine, ceruminous, and mammary. Eccrine are the most common and function primarily in thermoregulation by the production of sweat. The sweat (perspiration) eliminated by these glands contain water, salts, and some body wastes. Apocrine are confined to the anogenital and axillary regions of the body and produce sweat that contains fatty substances and proteins and may be analogous to sexual scent glands of animals. 

    The sebaceous glands produce a lipid based secretion called sebum, an oil that keeps the skin and hair from becoming dry and brittle ans serves as a bactericide. When an oil gland becomes plugged, the accumulation of dirt and oil results in a blackhead or pimple.

    Hair consists of a root, which grows in a hollow tube called a follicle, and a shaft. Hair helps protect the body. 

    Nails are made of tightly packed, keratinized cells. The nail body is the visible portion with a free edge which may extend past the distal end of the digit. The nail root extends into a fold of skin and is continuous with the stratum basale of the epidermis. The region of the nail body that overlies the nail matrix appears as a white crescent called the lanula. Nails protect the end of the digits and serve as "tools" for the manipulation of small objects. 

SOURCE:
http://www.hopperinstitute.com/cap_skin.html