BASIC SKELETAL SYSTEM AND IT FUNCTION

BASIC SKELETAL

KRYSA-SKELETAL-UNISEL-JPEG

FUNCTION OF SKELETAL SYSTEM

- SHAPE

Bone structure gives shape to the body. This shape changes as you grow, and your skeletal system determines your height, width and other factors, such as the size of your hands and feet. Body shape or type is genetically inherited. There are three main body shapes -- ectomorphs (tall and thin), mesomorphs (shorter and muscular) and endormorphs (apple or pear-shaped).

- SUPPORT

The skeleton provides support to the body and keeps your internal organs in their proper place. The vertebral column allows you to stand erect, while cavities -- hollow spaces in the skeleton are designed to hold your organs. For example, the skull holds the brain, the chest cavity holds your lungs and heart while the abdominal cavity holds your gastrointestinal organs. Additionally, the pelvis and leg bones are strong and thick to support the weight of the entire skeleton.

- MOVEMENT

The skeletal bones are held together by ligaments. Tendons attach your muscles to the bones of your skeleton. The muscular and skeletal systems work together to carry out bodily movement, and together they are called the musculoskeletal system. When muscles contract, the skeleton moves.

The shape of the skeletal system also impacts movement. The small bones of the foot allow for adaptation to all sorts of terrain, while the small bones in the hands allow for precise and detailed movement.

- PROTECTION

The skeleton protects vital organs from damage, encasing them within hard bones. The cranium bone --skull -- houses the brain, while the vertebral, or spinal, column protects the delicate spinal cord, which controls all bodily functions through communication with your brain. The bony thorax, comprised of the ribs and sternum, protects your heart and lungs.

- BLOOD CELL PRODUCTION AND STORAGE

The spongy tissue inside long bones, such as the femur, or thigh bone, have two types of marrow responsible for blood cell production. On average, 2.6 million red blood cells are produced each second by the bone marrow. Red bone marrow gives rise to blood cells while yellow bone marrow stores fat, which turns into red bone marrow in case of severe red blood cell depletion or anemia.

Skeletal bones also function as a storage bank for minerals, such as calcium and phosphorus. These minerals are necessary for vital body functions, such as nerve transmission and metabolism.

SOURCE:

-http://www.livestrong.com/article/115165-functions-skeleton/

ENVIRONMENTAL EPIDEMIOLOGY

                        DEFINE EPIDEMIOLOGY

Epidemiology is the study of how often diseases occur in different groups of people and why. Epidemiological information is used to plan and evaluate strategies to prevent illness and as a guide to the management of patients in whom disease has already developed.

                  FUNCTION OF EPIDEMIOLOGY

• Health surveillance, monitoring and analysis
• Investigation of disease outbreaks, epidemics and risk to health
• Establishing, designing and managing health promotion and disease prevention programmes
• Enabling and empowering communities to promote health and reduce inequalities
• Creating and sustaining cross-Government and intersectoral partnerships to improve health and reduce inequalities
• Ensuring compliance with regulations and laws to protect and promote health
• Developing and maintaining a well-educated and trained, multi-disciplinary public health workforce
• Ensuring the effective performance of health services to meet goals in improving health, preventing disease and reducing inequalities
• Research, development, evaluation and innovation
• Quality assuring the public health function     

                 JOHN SNOW & EPIDEMIOLOGY

- John Snow was a British physician, born on the 15th of March, 1813. Born in one of the poorest regions of York in the United Kingdom. John Snow apprenticed as a surgeon, before becoming a physician in 1850 and moving to London.

- As the summer of 1854 wound down, a major cholera outbreak struck Soho, a neighbourhood in London, England. From August 31st to September 3rd, 127 people died of Cholera. Within a week, 500 people had died and around one in seven people who developed cholera eventually died from it. This all occurred within 250 yards of the Cambridge Street and Broad Street intersection.

- He examined the neighbourhood, and talked to everyone he could. He was looking for an underlying theme that linked these people together. He suspected some contamination of the water, but couldn’t find any organic matter in it, which you would expect under the Miasma theory. However, the more he looked, the more it seemed like the pump was responsible. Almost all the cases of cholera occurred close to the Broad Street Pump. There were only 10 cases that were closer to another pump. Of these, 5 preferred the water from the Broad Street Pump (and got their water from the Broad Street Pump) and 3 were children who went to school near the Broad Street Pump. The last two were unrelated, and likely just background levels of cholera in the population. This was pretty convincing, but Snow mapped it out to make sure that he was on the right track. You might recognize the map – it’s what we use for our blog banner here on Public Health Perspectives.

- Snow provided more evidence for his theory that the pump was responsible for the cholera outbreak. For example, there was a brewery on Poland Street where 535 people worked, that had a pump on the premises. However, while cholera raged outside, only 5 of these people developed it. He explained this by pointing out that those who worked at the brewery were allowed to drink some of the malt liquor they made – and the foreman suspected that they didn’t drink any water at all. And even if they did, they used the pump on site.

- The evidence Snow presented in favour of his findings were too compelling for the local council to ignore, and while there was resistance to this finding, Snow had said enough for the local council to remove the pump handle, halting the spread of the disease. But, as Snow later pointed out, he couldn’t be sure that this stopped the disease, and the incidence of the disease might have been declining. But the end result was the same – cholera cases went down.

- That is not to say that everyone believed him. The council may have taken the pump down, but it wasn’t until 1885, when Robert Koch identified V. cholerae as the bacillus causing the disease that he had proof of his theory. He was right, but wasn’t around to see this discovery himself.

- John Snow died on the 16th of June 1858, at the age of 45. His legacy still lives on, over a 150 years later.

SOURCE:

- http://blogs.plos.org/publichealth/2013/03/11/john-snow-the-first-epidemiologist/

- http://en.wikiversity.org/wiki/Epidemiology_and_Public_Health

- http://www.bmj.com/about-bmj/resources-readers/publications/epidemiology-uninitiated/1-what-epidemiology

FUNCTION OF THE INTEGUMENTARY SYSTEM

Epidermis

Structurally, the epidermis is a thick keratinued stratified squamous epithelium consisting of four distinct cell types and five distinct layers.

Cells of the Epidermis

Cells populating the epidermis include: Keratinocytes, Melanocytes, Merkel cells, and Langerhans cells.

Keratinocytes: The most numerous cells are the keratinocytes which produce keratin, a fibrous protein responsible for protective properties of the epidermis. They arise from the deepest part of the epidermis from cells undergoing almost continuous mitosis. The keratinocytes are organized into 4-5 cell layers depending on body location. By the time the cells reach the surface of the skin, they are dead, scale-like structures. Every 35-45 days a totally new epidermis occurs. In areas of highest friction ( hands, feet) both cell production and keratin formation is accelerated.

Melanocytes: located at the base of the epidermis. Specialized cells that synthesize the pigment melanin. Melanin protects the cell nucleus from the destructive effects of UV radiation. Since all humans have the same relative number of these cells, individual and racial differences in skin coloring are probably due to differences in melanocyte activity.

Langerhans cells: arise from the bone marrow and migrate to the epidermis and other areas of the body containing stratified squamous epithelial tissue. They are macrophages and cooperate with T helper cells to assist in the immune response.

Merkel cells: present in small numbers at the epidermal-dermal junction. Associated with a disc-like ending of a sensory nerve fiber, called a Merkel disc, which functions as a sensory receptor.

Layers of the Epidermis: 

In thick skin (palms, fingertips, soles of feet) the epidermis consists of five layers or strata: (from deep to superficial) stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum. Thin skin, which covers the rest of the body has only 4 layers, with the stratum lucidum absent.

Stratum basale: single layer of cuboidal to columnar shaped cells. It is separated from the dermis by the basement membrane. Some cells move toward the surface while others migrate into the dermis and gives rise to sweat and oil glands. Many mitotic cells are seen. About 25% of the cells in this layer are melanocytes.

Stratum spinosum: contains 5-10 rows of cells fitted closely together. The surface of the cells display minute spiney projections. Mitosis occurs here but not as frequently. Langerhans cells are scattered among the keratinocytes. Because cells superficial to this layer do not receive adequate nutrients, they become less viable and finally begin to die.

Stratum granulosum: thin zone consisting of 3-5 layers of flattened cells. Keratinization begins in this third epidermal layer. The plasma membranes of these cells also thicken so that they become more resistant to destruction. Langerhans cells are also found in this layer. At the upper border of this layer, the cells die and lysosomes begin to digest their organelles.

Stratum lucidum (clear layer): translucent band just above the S. granulosum. Consists of a few rows of flattened dead keratinocytes with indistinct boundaries. Present only in thick skin.

Stratum corneum: outermost layer; a broad zone 20-30 cell layers thick. Accounts for about 3/4 of the epidermal thickness. The shingle-like dead cells are remnants, completely filled with keratin fibrils, and are referred to as cornified or horny cells. Keratin provides a durable abrasion resistant and water-repellent "overcoat" protecting deeper cells from the environment.

Dermis:

The second major skin region, is a strong but flexible connective tissue layer. The cell types found in the dermis are fibroblasts, macrophages, and occasional mast cells and white blood cells. Its gel-like matrix is heavily embedded with collagen, elastin, and reticular fibers. The dermis is your "hide" and is richly supplied with nerve fibers, blood vessels, and lymphatic vessels. The major portions of hair follicles, as well as oil and sweat glands, reside in the dermis, but are derived from epidermal tissue. The dermis varies in thickness and it has two major layers: papillary and reticular.

Nails:

Scale-like modifications of the epidermis that forms a clear protective covering on the dorsum of the distal part of a finger or toe. Each nail has a free edge, a body, and a root embedded in the skin. The thickened proximal part of the nail bed - nail matrix - is responsible for nail growth. Nail cells are heavily keratinized. Nail body slides distally over the nail bed during growth.

Sweat Glands:

More than 2.5 million sweat glands are distributed over the entire body. Two types of sweat glands: eccrine and apocrine.

 Eccrine - more numerous especially on the palms, soles and forehead. They secrete a hypotonic solution (sweat) derived from blood plasma. It is 99% water with some other substances in it. Sweating is regulated by the sympathetic nervous system. Assists in thermoregulation. 

Apocrine - largely confined to the axillary and anogenital regions. They are larger in size. The secretions are the same as eccrine with the addition of fatty substances and proteins which make the secretions viscous. The secretions are odorless until bacterial decomposition occurs. Precise function unknown. Activated by the sympathetic nervous system during pain or stress.

Ceruminous Glands - secrete ear wax.

Mammary Glands - secrete milk.

Sebaceous (oil) Glands: Simple glands found all over the body except on the palms and soles. They are small on the body trunk and limbs and larger on the face, neck, and upper chest. Secrete an oily secretion called sebum. The sebum is usually ducted into a hair follicle. Sebum softens and lubricates the hair and skin and it has a bactericidal action. Acne is an active inflammation of the glands accompanied by "pimples." Acne is usually caused by bacteria, especially staphylococcus.


SOURCE:

- http://www.augustatech.edu/anatomy/chapter5.html