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434                                             MEDICAL JURISPRUDENCE

2.    Vesicants :    Producing blisters.   These may "be infected to form
pustules, e.g. cantharis, mylabris wasps ; war gases like lewisite,
mustard gas, etc.

3.   Necrotics   or   Corrosives :    Eroding   the   tissues   resulting   in
destruction and debris or ulceration, e.g. concentrated mineral
acids and alkalies; creosote, formaldehyde, oxalic acid, phenol,
salicylic acid, etc.

(Note. — In different concentrations some substances can produce either
of these effects externally or internally.)

II.   SYSTEMIC POISONS :    Substances  acting,  after being  absorbed,  at
remote sites.

A.   Non-specific  or  indiscriminate tissue  poisons,   causing  damage  to
many tissues.

1.   Affecting tissue respiratory  enzymes :   cyanide  ion,   etc.,  e.g.
hydrocyanic acid and cyanides, etc.

2.   Affecting  enzyme-components,  like  sulphydril  radical   (-SH),
e.g. antimony and arsenic preparations  (late, systemic effects).

3.   Affecting haemoglobin  (impeding oxygen transport), e.g. aceta-
nilide, carbon dioxide, carbon monoxide, coal-gas, phenacitin, etc.

4.   Affecting general metabolism, e.g. dinitrophenols, thyroid prepa-
rations, etc.

B.    Specific or Selectively acting poisons :

(Note. — Substances can have toxic actions, simultaneously, on more than
one system, giving a mixed picture.)

1.   Neurotropic Poisons:    affecting primarily the nervous system.
A.   Irritants :    Substances causing nervous hyperactivity.

(Note. — On admission the patient is quite likely to be in. a depressed
condition, due to fatigue from over-activity.)

(i)  Cerebral (including thalamic) :

(a)  Delirients :    Mild irritants of the brain producing
excitatory effects short of convulsions, e.g. amphe-
tamine, atropine, belladonna, datura, homatropine,
hyoscyamine, etc.

(b)  Convulsants :    Producing clonic  convulsions,  e.g.
absinthe, camphor, cocaine and derivatives, insulia
leptazol, nikethamide, nupercaine, picrotoxine, etc.

(Note. — There are other * apparent ? irritant poisons which,
really * depressants *.   These are classified Tinder Depressants

(ii) Spinal :    Causing    tetanic     (tonic)

brucine, nux vomica, strychnine, t^eT^aMe, etc,
(iii) Medullary :    Chiefly    affecting    tfee   vomiting   centre,
e.g. apomorphine.

B.   Depressants :    Decreasing   the  functional, activity   of  the
nervous system.                                     "

(i) Cerebral including thalanjic :

(a) Inebrl&nts :    Promoting exhifersttion and crafte
hj^peractiviiy due to aft ft infeMtiorL of hitter i

of
ether ;