The brain
Alcohol destroys vitamin B1 (thiamin), a nutrient that maintains a healthy central nervous system, and is necessary for the breakdown of alcohol in the body.
Wernicke-Korsakoff syndrome is a brain disorder due to malnutrition that occurs because of the thiamin deficiency in chronic alcohol dependence.
Once alcohol reaches the brain its ability to control behaviour and body functions is immediately affected. Rising BAC levels further affect the body and behavioural changes occur.
Alcohol is a central nervous system (CNS) depressant. Respiratory (breathing) rate, heart rate, and the control mechanisms in the brain are all depressed. This occurs due to the alcohol interfering with communications between nerve cells and all other cells - suppressing the activities of excitatory nerve pathways and increasing the activities of inhibitory nerve pathways.
As the BAC increases, more and more centres of the brain are affected.
The order in which alcohol affects the various brain centres is as follows:
Cerebral cortex - A person becomes more talkative, self-confident and less socially inhibited. They have trouble seeing, hearing, smelling, touching and tasting and the threshold for pain is raised.
Limbic system - subject to exaggerated states of emotion such as anger, aggressiveness, withdrawal and memory loss.
Cerebellum - muscle movements become uncoordinated.
Hypothalamus and pituitary gland - increased sexual behaviour, declined sexual performance and urinary excretion.
Medulla (brain stem) - the medulla controls or influences all of the bodily functions that you do not have to think about, like breathing, heart rate, temperature and consciousness. If the BAC gets high enough to influence the breathing, heart rate and temperature centres, a person will breath slowly or stop breathing altogether.
The heart
| Alcohol can: - protect the heart
- influence blood cholesterol levels
- make the blood clot less readily
|
It is thought that alcohol can lower levels of LDL (low-density lipoprotein) cholesterol and raise the levels of 'good' HDL (high-density lipoprotein) cholesterol in the blood.
This reduces the risk of plaque formation on the surface of arteries, helping to prevent blood vessels from narrowing and getting blocked. Alcohol also reduces the stickiness of blood, and so reduces the likelihood of clots.
It is generally accepted that no additional benefit comes from drinking more than two units a day, although a recent report in the BMJ (British Medical Journal) suggests that four units of alcohol a day may reduce the risk of coronary disease by about 25%.
19/05/2009