What is metabolism?

[gene]

YT2095 said in post #25 :

Pyrogens are what the body releases in response to foreign "invaders".

 

But i thought that if the body is invaded by foreigh invaders or bacteria, anitibodies or white blood cells would be produced instead of Pyrogens to combat these foreign invaders?

[YT2095]

your quite right. white cells are 1`st on the scene, but don`t inherently generate heat of thier own, it`s the pyrogens that are released that are responsible for that, as we were discussing Hyperthermia

[gene]

Oh... so pyrogens is not a cell. But some sort of chemical whereby is released to kill bacteria and foreign invaders right?

[gene]

YT2095 said in post #6 :

the temp increase is also the bodys way of killing the viral agent as they often can only exist within a certain temperature range. to hot (even by only a few degrees) will kill them. so we run a temperature of 102 for a while, we feel bad, but they feel worse!

oh yA!

one more thing... i was thinking about it...

You said that increase in temp. also help kill bacteria (Is bacteria= viral agents?). But i thought only 100 degree celsius than the bacteria is completely killed? It will be crazy to run at 100 degrees... We would have become roast chicken...

anyway 102 farienheit? is equal to how many degrees c.?

[Glider]

jordan said in post #23 :

Does pyrogens refer to the bodies internal respnse rather than an external stimulus or is that just the way you worded your response?

The term Pyrogen refers to any substance that causes an elevation in core temperature. There are exogenous (exo = outside; gennan = to produce) pyrogens and endogenous (endo = within) pyrogens. The most common cause of fever (pyrexia) are exogenous pyrogens, which are usually toxins (particularly bacterial toxins) and those produced as a result of bacterial and viral infection. However, other causes of fever can include heart attacks, tumours, tissue trauma, reaction to vaccines and so-on.

 

The way it works is this: exogenous pyrogens cause monocytes and macrophages (both are kinds of white cell called phagocytes) to synthesise and release endogenous pyrogens, which are small proteins. These circulate to the anterior hypothalamus (the area responsible for the homoeostatic maintenance of body temperature), and cause cells in the preoptic area to release substances called prostoglandins, which re-set the hypothalamic 'thermostat' (internal comparator) to a higher level.

 

gene said in post #24 :

Is Hypothermia or Hyperthermia a chronic disease?

 

Base on my understanding, chronic diease means it exist for a very long time right?

Neither condition is a disease, but they can be chronic. However, you should note that Hyperpyrexia and hyperthermia are terms used to indicate fever above 40 degrees C. Prolonged hyperthermia is harmful (particularly in children), and can result in febrile seizures, tissue damage and death. So hyperthermia per se cannot be chronic, pyrexia can. On the other hand, hypothermia simply means a subnormal body temperature and is encountered (as a result of pathology) much less frequently than fever. What we are talking about here is Pyrexia, which indicated temperatures above 38 degrees C, but below 40 (104F). All these terms refer to body temperature (i.e. changes in core temperature), not changes in peripheral temperature. We are very much more tolerant of changes in temperature of, for example, skin, limbs hands and feet than we are of changes in core temperature, which must be maintained very closely around 38 degrees Celsius.

 

There are conditions which upset the hypothalamic 'temperature control'. For example, Hypo- and Hyperthyroidism. One of the symptoms of hyperthyroidism is heat intolerance. Hyperactivity of the thyroid results in an elevated metabolism, weight-loss, an elevated core temperature, profuse sweating and feeling uncomfortably hot in conditions that are comfortable to everyone else. There are also psychological effects, nervousness, anxiety and emotional lability (instability) are also manifest. The symptoms of hypothyroidism (also known as myxedema) are more or less the opposite of these; i.e. mild hypothermia and cold intolerance, reduced metabolism, weight gain sluggish mental processes, tiredness and flattened emotional responses. Lesions (damage) to the hypothalamus can also cause long-term temperature dysregulation.

 

gene said in post #26 :

But i thought that if the body is invaded by foreigh invaders or bacteria, anitibodies or white blood cells would be produced instead of Pyrogens to combat these foreign invaders?

They are. And phagocytes are a kind of white cell. White cells are the immediate defence, and directly attack the pathogens. They also release endogenous pyrogens.

 

gene said in post #28 :

Oh... so pyrogens is not a cell. But some sort of chemical whereby is released to kill bacteria and foreign invaders right?

Partially right. A pyrogen is not a cell. It is a small protein released by cells, but it is not released to kill bacteria and viruses (see below).

 

gene said in post #29 :

oh yA!

one more thing... i was thinking about it...

You said that increase in temp. also help kill bacteria (Is bacteria= viral agents?). But i thought only 100 degree celsius than the bacteria is completely killed? It will be crazy to run at 100 degrees... We would have become roast chicken...

 

Quite right. The increase in core temperature does not help kill bacteria and viruses to any significant extent.

 

Bacteria are not viruses; bacteria are alive and capable of reproduction, viruses are not alive (they are 'viable') and are incapable of independent reproduction. They require a host cell to produce more of themselves. In some cases, fever can inhibit the rate of bacterial reproduction, but many bacteria can live in temperatures higher than those that would kill us very quickly (a core temperature of around 110 - 112 Fahrenheit, 43.3 - 44.4 Celsius is fatal to us). Viruses can exist in very high temperatures. Even the HIV virus (which, as viruses go, is quite pathetic outside of a host) requires temperatures of at least 60 degrees Celsius to destroy it. Many viruses can cope easily with temperatures in excess of 100 degrees Celsius.

 

A core temperature sufficient to kill most pathogens would kill us instantly. There are a very few exceptions, for example, the causative organisms in gonorrhea and neurosyphilis don't like heat, but even then, the temperature required to wipe them all out would also severely damage us, if not kill us. As for viruses, they can't reproduce on their own. They insert their RNA into our cells and our own cells begin producing new viruses, so the only way to kill them would be to kill our own cells.

 

The principal benefit of fever is the elevated metabolism. This means our own chemical process are occurring at a higher rate, which means we heal faster (repairing and replacing damaged cells more quickly) and we produce more white cells and antibodies faster.

 

anyway 102 farienheit? is equal to how many degrees c.?

102 Fahrenheit is about 39 degrees Celsius.

 

For more detailed information see:

 

Kandel, E.R., Schwartz, J. H., & Jessell, T. M. (1991). Principles of Neural Science. International: Prentice-Hall international Inc.

 

Tortora, G. J. and Anagnosticos, N. P. (1987). Principles of Anatomy and Physiology (5th Ed.). New York: Harper and Row.

 

Watson, J. E., (1979). Medical-Surgical Nursing and Related Physiology (2nd Ed.). London: W.B. Saunders.

[gene]

Woo. I need some clarification. What actually is Pyrogen? (Sorry i got confused with the intense amount of information )

So, pyrogen is a small protein realeased by white blood cell to increaese the tempeature? Beacause this is what i am understanding.

1. Exogenous pyrogens: are they pyrogens that are released outside of body? To prevent them from entering our body or what?

2. Endogenous pyrogens: substances that are released within out body to combat the bacteria or invaders already existing in our body. is it?

Thanks

[Glider]

You answered your own question (what is a pyrogen?) in your post.

 

The answer to question 1. is in the first paragraph of the above post. The answer to question 2. is in the second paragraph.

 

Endogenous pyrogens are not released to combat bacteria or other 'invaders'. They are released to re-set the neural 'thermostat' to a higher level to help the body combat the infection by elevating metabolism (faster healing and antibody production). The elevation in core temperature can also inhibit bacterial growth in some cases. One of the mechanisms of inhibition is that fever and the elevation in metabolism causes certain minerals (particularly iron) that bacteria need for reproduction to be locked up in the liver.

[gene]

er. Yah, i read your post. But i do no understand what is the difference between

There are exogenous (exo = outside; gennan = to produce) pyrogens and endogenous (endo = within) pyrogens.

EEEEeee... I'm confused. What do you mean but "outside" pyrogens and "within pyrogens"????

 

I simply do not understand your explanation.

[Glider]

Exogenous pyrogens are introduced into the body from the ouside (e.g. bacteria etc.), or produced within the body by organisms that came from the outside (e.g. bacterial toxins). Either way, the original source is outside the body.

 

Endogenous pyrogens are produced inside the body, by the body (monocytes and macrophages).

[gene]

OH..... oK...

I got it now...

Thanks