This pamphlet is a synopsis on the topic: 'Brain damage associated with
alcohol abuse,' from several perspectives. Firstly, a definition of alcohol,
its potency; factors involved in ingestion and absorption. Secondly, an outline
emphasizing the anatomical and physiological components of the brain. Their
orientations and ensuing direct and indirect effects on the afferent neurones
( that transmit impulses to the central nervous system ( CNS )), and efferent
fibres,
exempli gratia
, the effectors of the muscle or glands. Concluding with a soupçon of
information about behavioural effects, organ systems, anterograde amnesia,
three consecutive phases in physical dependence syndrome; and
Wernicke-Korsakoff's syndrome.
ETHANOL
Alcohol is known as 'ethyl alcohol' and 'ethanol'. The word 'ethanol', rather
than 'alcohol', is employed in this pamphlet, to conform with its approval by
the International Union of Pure and Applied Chemistry ( IUPAC ).
Ethanol is developed by either fermentation or distillation from agricultural
products and comprises of Hydroxyl ( OH ) type organic compounds connected to a
single carbon atom,
videlicet
, three hydrogen atoms adjoining a single carbon atom ( CH
3
OH ). The potency of ethanol beverages are variable. The Alcohol & Drug
Foundation ( Victoria ) report that 'beer has an approximate ethanol content
range between 2-5% x volume of 425 and 285 ml respectively, wine approximates
between 10-20% x volume of 120 and 60 ml, and distilled spirits; 40% x volume
of 30 ml' (
i.
).
INGESTION
Ethanol is usually ingested orally and is absorbed into the body from both the
upper and lower aspects of the alimentary canal at absorption levels of
approximately 75% and 25% respectively (
ii.
). Its rate of absorption is greater in the small intestine than the stomach (
iii.
). Following ingestion, the blood ethanol ( alcohol ) level ( BAL ) may peak
within 30 to 60 minutes (
iv.
).
The level of ethanol, and the determining factors in absorption are based on:
the percentage level of ethanol per drink, the condition of the stomach, the
variable time factors of absorption, and the rate of metabolism determined by
liver mass, tolerance and genetic factors.
The absorption rate is less at the low level of the ethanol percentage range,
whereas it is more at the high level (
v.
). A high level of ethanol in a void stomach may cause pylorospasms,
videlicet,
convulsions of the
pyloric sphincter
, that will obstruct the path into the small intestine; thus retarding the
absorption rate. The rate is also determined by either presence or absence of
food stuffs ( solids/liquids ) in the upper aspects of the
gastrointestinal
( GI ) tract (
vi.
).
Presence of food stuffs, particularly some fatty substances, slow down the
rate of ethanol absorption, whereas its absence - or ethanol combined with
carbonated fluids - may accelerate absorption by approximately 20% per dose (
vii.
). Inflamed peptic ulcers may either inhibit or stimulate absorption. The rate
of absorption is affected also by temperature. At environmental temperature, it
is absorbed rather rapidly, whereas chilled, it absorbs slowly (
viii.
).
The ethanol molecule ( CH
3
CH
2
OH ) is water and fat soluble and therefore absorb quite readily into all
tissue including the brain. It also passes over the placenta - a structure that
exchanges oxygen, nutrients, carbon dioxide and wastes between the
foetal
and maternal circulation - to an infant's BBB.
Pregnant women consuming several drinks per day expose their unborn infants to
foetal alcohol syndrome ( FAS ), which include: anomalous cardiac function,
arrested intellectual development, head and facial disfigurement, and
abnormalities to the cartilaginous, fibrous and synovial joints; as well as the
extremities ( see: Cox C.
et al.
'Drugs & Drug Abuse', Addiction Research Foundation,
2nd ed
, p.283 ). The scientific community has not established safe levels of ethanol
intake for pregnant women.
INSPIRATION & EXCRETION
Vaporized, ethanol can be absorbed by inspiration ( inhalation of air
into the lungs ) into the blood stream, and small quantities can be excreted by
expiration ( exhalation of air from the lungs ). The interchange of oxygen ( O
2
> CO
2
)
from the left ventricle, and carbon
dioxide ( CO
2
> O
2
) from the right ventricle of the pulmonary blood supply, ocurrs - during
inhalation - between the capillary network and the
alveoli
; and during exhalation the carbon dioxide is removed from the lungs. Ethanol
retards the rate of incoming atmospheric air and the interchange process
between the
alveoli
and the pulmonary blood capillaries.
Vaporized, ethanol can be absorbed by inspiration ( inhalation of air
into the lungs ) into the blood stream, and small quantities can be excreted by
expiration ( exhalation of air from the lungs ). The interchange of oxygen ( O
2
> CO
2
)
from the left ventricle, and carbon
dioxide ( CO
2
> O
2
) from the right ventricle of the pulmonary blood supply, ocurrs - during
inhalation - between the capillary network and the
alveoli
; and during exhalation the carbon dioxide is removed from the lungs. Ethanol
retards the rate of incoming atmospheric air and the interchange process
between the
alveoli
and the pulmonary blood capillaries.
