Experimental fever

Pyrogenalum is a highly potent nonprotein exogenous pyrogen consisting of LPS. It may be synthesized or produced by Pseudomonas aeruginosa bacteria and by Salmonellae of Typhus-Paratyphus group. The onset of fever in response to pyrogen injection begins after a certain latent period whose duration is shorter in the case of an endogenous pyrogen injection. The latent period depends on the nature and potency of pyrogen, and the way of injection. In the case of intravenous injection the latent period is 15-40 minutes, in the case of subcutaneous injection it is 30 to 80 minutes, in the case of injection into cerebral ventricles - it is considerably less than 15 minutes. Repeated injections of exogenous pyrogens produce tolerance, while repeated injections of endogenous ones do not. The blockade of the system of mononuclear phagocytes with Indian ink prevents development of fever after introduction of exogenous pyrogens.

Hyperthermia, unlike fever, is a temporary increase of body temperature due to the disturbance of thermoregulatory mechanisms and brake-down of the balance between thermogenesis and heat emission (loss). Hyperthermia is extremal heat stress, when the ability of the organism to emit heat is lower than heat production, hence an abnormal rise of body temperature against the background of thermoregulatory failure. Hyperthermia results in dehydration, circulatory disorders and hypoxia. Fever does not produce either of the aforementioned changes characteristic of hyperthermia.

¹ Sir Hans Adolf Krebs, German (after 1933 English) biochemist, born August 25, 1900, Hildesheim; died November 22, 1981, Oxford. Nobel prize winner of 1953 in Physiology or Medicine.

² Max Rubner (1854-1932), German physiologist, pathologist and hygienist. Founder of scientific Dietetics and Nutritiology, pioneer of biocalorimetry, who has precisely correlated animal heat to oxidation and catabolism in the body.

3. Complete the sentences below. Insert no more than three words in each gap.

1. Fever in adults is characterized by the limitation of ____ with the simultaneous intensification of ____.

2. The limitation of heat loss is carried out by the vasoconstriction of _____.

3. The decrease in skin temperature results in the ________ signalization of cold thermo receptors and shivering.

4. The spinal oscillator is responsible for the shivering reflex showing itself as simultaneous contraction of __________.

5. The first stage of the fever is _________.

6. Contractile and non-contractile thermogeneses increase from 20%to 60% due to ________ and the stimulation of the _________.

7. At stadium incrementi the activation of the hypothalamus-hypophysis-___ takes place.

4. Choose the correct answer from а, в or c.

1. Domination of carbohydrates oxidation causes the increase of the respiratory _____ up to 1.0.

1. capacity

2. expansion

3. coefficient

2. Heat production and heat are balanced at stadium fastigii.

1. exhaustion

2. elimination

3. emission

3. Stadium decrementi results from a recourse of the set-point of temperature _____ down to normal.

1. homeostasis

2. drop

3. indicator

4. The onset of fever in response to pyrogen injection begins after acertain period.

1. calm

2. latent

3. important

5. The latent period depends on the nature and potency of ____, and the way of injection.

1. solution

2. drug

3. pyrogen

6. Repeated injections of pyrogens produce tolerance.

1. exogenous

2. different

3. endogenous

7. Hyperthermia, unlike fever, is a increase of body temperature.

1. constant

2. temporary

3. sudden

8 Hyperthermia results in dehydration, circulatory and hypoxia.

a. effect

b. collapse

c. disorders