Tampilkan postingan dengan label Health Study. Tampilkan semua postingan
Tampilkan postingan dengan label Health Study. Tampilkan semua postingan

Gram positive bacteria

23.00 | Label:


Gram positive bacteria: are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain (safranin or fuchsine) and appearing red or pink. Gram-positive organisms are able to retain the crystal violet stain because of the high amount of peptidoglycan in the cell wall. Gram-positive cell walls typically lack the outer membrane found in Gram negative bacteria.
gram positive bacteria
gram positive bacteria
 Characteristics
  • cytoplasmic lipid membrane
  • thick peptidoglycan layer
  • teichoic acids and lipoids are present, forming lipoteichoic acids, which serve to act as chelating agents, and also for certain types of adherence.
  • capsule polysaccharides (only in some species)
  • flagellum (only in some species)
  • if present, it contains two rings for support as opposed to four in Gram-negative bacteria because Gram-positive bacteria have only one membrane layer.
  • The individual peptidoglycan molecules are cross-linked by pentaglycine chains by a DD-transpeptidase enzyme. In gram-negative bacteria, the transpeptidase creates a covalent bond directly between peptidoglycan molecules, with no intervening bridge.
Both Gram-positive and Gram-negative bacteria may have a membrane called an S-layer. In Gram-negative bacteria, the S-layer is attached directly to the outer membrane. In Gram-positive bacteria, the S-layer is attached to the peptidoglycan layer. Unique to Gram-positive bacteria is the presence of teichoic acids in the cell wall. Some particular teichoic acids, lipoteichoic acids, have a lipid component and can assist in anchoring peptidoglycan, as the lipid component is embedded in the membrane.
Daftar Pustaka:

  • Digg
  • Del.icio.us
  • StumbleUpon
  • Reddit
  • RSS

read comments

GENES & BLOOD TYPE

21.42 | Label:

Blood is a complex, living tissue that contains many cell types and proteins. A transporter, regulator, and defender, blood courses through the body carrying out many important functions.
PROTEINS & BLOOD TYPES 
Distinct molecules called agglutinogens (a type of antigen) are attached to the surface of red blood cells. There are two different types of agglutinogens, type "A" and type "B". Each type has different properties. The ABO blood type classification system uses the presence or absence of these molecules to categorize blood into four types:

.Another level of specificity is added to blood type by examining the presence or absence of the Rh protein. Each blood type is either positive "+" (has the Rh protein) or negative "-" (no Rh protein). For example, a person whose blood type is "A positive" (A +), has both type A and Rh proteins on the surface of their red blood cells.

BLOOD TYPE IS GENETIC 

The A and B antigen molecules on the surface of red blood cells are produced by two different enzymes. These two enzymes are encoded by different versions, or alleles, of the same gene: A and B.The A and B alleles code for enzymes that produce the type A and B antigens respectively. A third version of this gene, the O allele, codes for a protein that is not functional and does not produce surface molecules. Two copies of the gene are inherited, one from each parent. The possible combinations of alleles produce blood types in the following way:


Daftar Pustaka:

  • Digg
  • Del.icio.us
  • StumbleUpon
  • Reddit
  • RSS

read comments

What is diarrhea?

02.30 | Label:


Diarrhea is an increase in the frequency of bowel movements or a decrease in the form of stool (greater looseness of stool). Although changes in frequency of bowel movements and looseness of stools can vary independently of each other, changes often occur in both.

Diarrhea needs to be distinguished from four other conditions. Although these conditions may accompany diarrhea, they often have different causes and different treatments than diarrhea. These other conditions are:
  1. Incontinence of stool, which is the inability to control (delay) bowel movements until an appropriate time, for example, until one can get to the toilet
  2. Rectal urgency, which is a sudden urge to have a bowel movement that is so strong that if a toilet is not immediately available there will be incontinence
  3. Incomplete evacuation, which is a sensation that another bowel movement is necessary soon after a bowel movement, yet there is difficulty passing further stool the second time
  4. Bowel movements immediately after eating a meal

How is diarrhea defined?

Diarrhea can be defined in absolute or relative terms based on either the frequency of bowel movements or the consistency (looseness) of stools.
Frequency of bowel movements. Absolute diarrhea is having more bowel movements than normal. Thus, since among healthy individuals the maximum number of daily bowel movements is approximately three, diarrhea can be defined as any number of stools greater than three. "Relative diarrhea" is having more bowel movements than usual. Thus, if an individual who usually has one bowel movement each day begins to have two bowel movements each day, then relative diarrhea is present-even though there are not more than three bowel movements a day, that is, there is not absolute diarrhea.
Consistency of stools. Absolute diarrhea is more difficult to define on the basis of the consistency of stool because the consistency of stool can vary considerably in healthy individuals depending on their diets. Thus, individuals who eat large amounts of vegetables will have looser stools than individuals who eat few vegetables. Stools that are liquid or watery are always abnormal and considered diarrheal. Relative diarrhea is easier to define based on the consistency of stool. Thus, an individual who develops looser stools than usual has relative diarrhea--even though the stools may be within the range of normal with respect to consistency.
daftar pustaka:

  • Digg
  • Del.icio.us
  • StumbleUpon
  • Reddit
  • RSS

read comments

Hemoglobin

01.30 | Label:


Hemoglobin is the protein molecule in red blood cells that carries oxygen from thelungs to the body's tissues and returns carbon dioxide from the tissues to the lungs. Hemoglobin is made up of four protein molecules (globulin chains) that are connected together. The normal adult hemoglobin (Hbg) molecule contains 2 alpha-globulin chains and 2 beta-globulin chains. In fetuses and infants, there are only a few beta chains and the hemoglobin molecule is made up of 2 alpha chains and 2 gamma chains. As the infant grows, the gamma chains are gradually replaced by beta chains.
Each globulin chain contains an important central structure called the heme molecule. Embedded within the heme molecule is iron that transports the oxygen and carbon dioxide in our blood. The iron contained in hemoglobin is also responsible for the red color of blood.
Hemoglobin also plays an important role in maintaining the shape of the red blood cells. Abnormal hemoglobin structure can, therefore, disrupt the shape of red blood cells and impede its function and its flow through blood vessels.
Hemoglobin is usually measured as a part of the complete blood count (CBC) from a blood sample. Several methods exist for measuring hemoglobin, most of which are done currently by automated machines designed to perform several different tests on blood. Within the machine, the red blood cells are broken down to get the hemoglobin into a solution. The free hemoglobin is exposed to a chemical containing cyanide which binds tightly with the hemoglobin molecule to form cyanmethemoglobin. By shining a light through the solution and measuring how much light is absorbed (specifically at a wavelength of 540 nanometers), the amount of hemoglobin can be determined.
The hemoglobin level is expressed as the amount of hemoglobin in grams (gm) per deciliter (dl) of whole blood, a deciliter being 100 milliliters.
The normal ranges for hemoglobin depend on the age and, beginning in adolescence, the gender of the person. The normal ranges are:
  • Newborns: 17-22 gm/dl
  • One (1) week of age: 15-20 gm/dl
  • One (1) month of age: 11-15gm/dl
  • Children: 11-13 gm/dl
  • Adult males: 14-18 gm/dl
  • Adult women: 12-16 gm/dl
  • Men after middle age: 12.4-14.9 gm/dl
  • Women after middle age: 11.7-13.8 gm/dl
All of these values may vary slightly between laboratories. Some laboratories do not differentiate between adult and "after middle age" hemoglobin values.
What does a low hemoglobin level mean?
A low hemoglobin is referred to as anemia. There are many reasons for anemia.
Some of the more common causes are:
  • loss of blood (traumatic injury, surgery, bleeding colon cancer or stomach ulcer),
  • nutritional deficiency (iron, vitamin B12, folate),
  • bone marrow problems (replacement of bone marrow by cancer,
  • suppression by chemotherapy drugs,
  • kidney failure), and
  • abnormal hemoglobin (sickle cell anemia).
What does a high hemoglobin level mean?
Higher than normal hemoglobin levels can be seen in people living at high altitudes and in people who smoker. Dehydration produces a falsely high hemoglobin which disappears when proper fluid balance is restored.
Some other infrequent causes are:
  • advanced lung disease (for example, emphysema),
  • certain tumors,
  • a disorder of the bone marrow known as polycythemia rubra vera, and
  • abuse of the drug erythropoietin (Epogen) by athletes for blood doping purposes.
Sickle cell disease is a genetic condition in which the quality of hemoglobin is defective. This condition can cause abnormal hemoglobin which, in turn, can result in abnormally shaped (sickled) red blood cells. These abnormal red blood cells cannot easily pass through small blood vessels and, therefore, could deprive the body organs of adequate oxygen.
Sickle cells also have a shorter life span than normal red blood cells (10-20 days compared to 120 days). This rapid turn over may result in inadequate time to replace the red blood cells and may result in anemia.
When red blood cells die, the hemoglobin within them is released and broken up: the iron in hemoglobin is salvaged, transported to the bone marrow by a protein called transferrin and used again in the production of new red blood cells; the remainder of the hemoglobin becomes a chemical called bilirubin that is excreted into the bile which is secreted into the intestine, where it gives the feces their characteristic yellow-brown color.
Although the changes that produce abnormal hemoglobins are rare, several hundred abnormal (or more precisely, "variant") hemoglobins exist. These have accumulated over the millions of years of human existence. Most variant hemoglobins function normally, and are only found through specialized research techniques. Some hemoglobins, however, do not function normally and can produce clinical disorders, such as sickle cell disease.
Genes can suffer damage to an extent that they no longer produce normal amounts of hemoglobin. Usually, only one of the sets of hemoglobin genes is affected, that is the alpha gene set or the beta gene set. For example, one of the two beta globin genes may fail to produce a normal quantity of beta chain protein. The alpha globin gene set will continue to produce a normal quantity of alpha chain protein. An imbalance develops in the amount of alpha chain and beta chain protein in the cell. There is too much alpha chain for the amount of beta chain that is present. This imbalance is called "thalassemia ". In this example, it would be beta thalassemia, because it is the beta chain gene that has failed. An analogy would be cars coming out of the factory. Engines and bodies must be made in equal numbers to have functional automobiles. If the engine plant goes on strike (thalassemia), the bodies produced by the body plant are useless.

daftar pustaka:

  • Digg
  • Del.icio.us
  • StumbleUpon
  • Reddit
  • RSS

read comments
Langganan: Postingan (Atom)