THEME: REACTIVITY and RESISTANCE
TEXT: ONTOGENESIS OF REACTIVITY
Listen to the recording. Repeat each medical term during the pause in the recording. Mind the stress.
| acidosis | ацидоз |
| adrenal medulla | мозговое вещество надпочечника |
| basal metabolic rate (BMR) | основной обмен |
| bradycardia | брадикардия |
| brown fat | бурая жировая клетчатка |
| cardiomyocyte | кардиомиоцит |
| catatoxic reactions | кататоксические реакции |
| catecholamine | катехоламин |
| epinephrine | адреналин, эпинефрин |
| fetal hemoglobin (Hb) | фетальный гемоглобин |
| phosphofructokynase | фосфофруктокиназа |
| lactate | лактат |
| pathogenic | патогенный, болезнетворный |
| sanogenic | саногенный, оздоравливающий |
| secretory | секреторный (относящийся к процессу или продуктам секреции) |
| syntoxic reactions | синтоксические реакции |
Without looking into the text listen to the recording,
Say what information you have gathered.
Listen to the text again.
Now, read the text silently, trying to grasp all the details of the contents.
Then, read it simultaneously with the speaker, trying to catch up with the tempo.
After that read the text aloud, trying to imitate the intonation.
According to Hans Selye1, the term "catatoxic reactions" means active protection while the term "syntoxic reactions" is used to define passive protection. Catatoxic and syntoxic reactions are intermingled parts of any adaptive process.
The dependence of many protective reactions on central mechanisms integrating reactivity is not too strong. Being adaptive at the level of the cell, tissue and organ, they may be pathogenic at the level of the organism as a whole. Thus, the effects of the mediators of inflammation within the limits of the inflammed zone may be sanogenic; however, the effects of their massive penetration into the systemic circulation are pathogenic. Mechanisms of reactivity are only relatively beneficial and potentially pathogenic.
Ontogenesis is the process of asynchronous expression and repression of the unfolding genetic programs. That is why individuals of different ages have different reactivity. New born human beings, like vertebrate and invertebrate animals at early stages of their ontogenesis, are more resistant to acute hypoxia (Sirotinin's2 rule), since:
1) isoenzymes of PhFK (phosphofructokynase) are insensitive to increased levels of lactate acidosis;
2) the amount of fetal Hb in blood circulation is much greater;
3) the absolute basal metabolic rate (BMR) is markedly lower;
4) there are certain peculiarities in the catecholamine status and the amount of receptors of catecholamines on cardiomyocytes, such as:
a) secretion of catecholamines by the adrenal medulla cells occur in response to hypoxia in secretory cells;
b) epinephrine/nor-epinephrine ratios in adrenal medulla secretions are 1:1; compared to predominance of epinephrine in adults. Nor-epinephrine effectively increases surfactant secretion in lungs. It is also significant for cold adaptation of neonates via urgent lipolysis in brown fat.
c) the number of epinephrine receptors in cardiomyocytes is not sufficient for induction of tachycardia. Bradycardia is more effective response for hypoxia for fetal conditions. All this is also true for anti-hypoxial mechanisms of diving animals, like seal or cachalot.
Hans Hugo Bruno Selye (see p. 31 below), Austrian-Hungarian (after 1932 — Canadian) pathophysiologist and endocrinologist, born January 26, 1907, Vienna, Austria-Hungary, died October 16, 1982, Montreal, Canada. Discovered stress, formulated the concept of eustress and distress, experimentally proved the existence of polyetiological diseases.
2 Sirotinin Nicolay Nicolaevich — Russian pathophysiologist, born November 26,1896, Saratov, Russia, died April 4, 1977, Kyev, USSR. Founder of Aerospace Pathophysiology, made outstanding contribution in research of high altitude disease, invented stepwise principle of mountain acclimatization.
Do the following statements agree with the information given in the text?
| Write | |
| TRUE | if the statement agrees with the information |
| FALSE | if the statement contradicts the information |
1. The term "catatoxic reactions" is used to define passive protection while the term "syntoxic reactions" is used to define active protection.
2. Catatoxic and syntoxic reactions are parts of any adaptive process.
3. The dependence of many protective reactions on central mechanisms integrating reactivity is very strong.
4. The effects of the mediators of inflammation within the limits of the inflammation zone may be pathogenic; however, the effects of their penetration into the circulation are sanogenic.
5. Mechanisms of reactivity are only relatively beneficial and potentially pathogenic.
6. Ontogenesis is the process of asynchronous repression and expression of the unfolding genetic programmes.
7. Individuals of different ages have different reactivity.
8. New born human beings, unlike vertebrate and invertebrate animals at early stages of their ontogenesis, are more resistant to acute hypoxia.
Listen to the following questions and repeat them. Mind the intonation in general and special questions. Then answer the questions and practice them with your partner.
1. Is the term "catatoxic reaction" used to define passive protection?
2. What does the term "catatoxic reactions" express?
3. Parts of what process are catatoxic and syntoxic reactions?
4. How strong is the dependence of protective reactions on central mechanisms integrating reactivity?
5. How may the mechanisms of reactivity be characterized in terms of usefulness?
6. What is ontogenesis?
7. Why are new born human beings more resistant to acute hypoxia then adults?
8. Who was Nicolay Sirotinin and what is his contribution into ontogenetic aspects of reactivity doctrine? (Use the text "Medi cine through Biographies" )
9. Who was Hans Selye and what is his contribution into reactivity doctrine? (Use the text "Medicine through Biographies")