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3-D model biology
Bio - Excretion
Biology Scheme of work 2010-2011
HOW ALCOHOL AFFECTS THE BRAIN
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HOW ALCOHOL AFFECTS THE BRAIN
Parts and Function of the Brain
- the part of the brain below the back of the cerebrum. It regulates balance, posture, movement, and muscle coordination.
Frontal Lobe of the Cerebrum
- the top, front regions of each of the cerebral hemispheres. They are used for reasoning, emotions, judgment, and voluntary movement.
- the lowest section of the brainstem (at the top end of the spinal cord); it controls automatic functions including heartbeat, breathing, etc.
Occipital Lobe of the Cerebrum
- the region at the back of each cerebral hemisphere that contains the centers of vision and reading ability (located at the back of the head).
Parietal Lobe of the Cerebrum
- the middle lobe of each cerebral hemisphere between the frontal and occipital lobes; it contains important sensory centers (located at the upper rear of the head).
- a gland attached to the base of the brain (located between the Pons and the Corpus Callosum) that secretes hormones.
- the part of the brainstem that joins the hemispheres of the cerebellum and connects the cerebrum with the cerebellum. It is located just above the Medulla Oblongata.
- a thick bundle of nerve fibers that runs from the base of the brain to the hip area, running through the spine (vertebrae).
Temporal Lobe of the Cerebrum
- the region at the lower side of each cerebral hemisphere; contains centers of hearing and memory (located at the sides of the head).
How Alcohol Affects the Brain
General Effects of Alcohol on the Brain
Alcohol can affect several parts of the brain, but in general, alcohol contracts brain tissue and depresses the central nervous system. Also, alcohol destroys brain cells and unlike many other types of cells in the body, brain cells do not regenerate. Excessive drinking over a prolonged period of time can cause serious problems with cognition and memory.
When alcohol reaches the brain, it interferes with communication between nerve cells, by interacting with the receptors on some cells. The alcohol suppresses excitatory nerve pathway activity and increases inhibitory nerve pathway activity. Among other actions, alcohol enhances the effects of the inhibitory neurotransmitter GABA. Enhancing an inhibitor has the effect of making a person sluggish. Also, alcohol weakens the excitatory neurotransmitter glutamine, which enhances the sluggishness even farther.
Chemical Effects of Alcohol on the Brain
To understand how alcohol interferes with brain function, it is necessary to know a little bit about normal brain function. The brain is the control center of the body - it controls all the systems in your body including your muscular system, your respiratory system and your digestive system. But how does the brain control these functions? It does so by using a series of chemical, electrical and physical signals from cell to cell. Within the cell, electrical signals are used for transmission, but between cells, chemical signals are used - these chemical signals are called neurotransmitters.
The gap between cells where neurotransmitters are active is called the synapse. The expelled neurotransmitter travels across the synapse and binds to a protein on the receiving cell membrane called a receptor, which is specific for that neurotransmitter. This action causes some change in the receiving cell, either chemical, electrical or physical, which can excite the receiving cell to perform an action or inhibit the receiving cell from performing an action.
When alcohol is introduced to the synapse, the normal neurotransmission may be affected.
Effects of Alcohol on Brain Parts
The cerebral cortex and alcohol
The cerebral cortex processes information from your senses, processes thoughts, initiates the majority of voluntary muscle movements and has some control over lower-order brain centers. In the cerebral cortex, alcohol can:
Affect thought processes, leading to potentially poor judgement.
Depresses inhibition, leading one to become more talkative and more confident.
Blunts the senses and increases the threshold for pain.
As the BAC increases, these effects get more pronounced.
The cerebellum and alcohol
The cerebellum coordinates muscle movement. The cerebral cortex initiates the muscular movement by sending a signal through the medulla and spinal cord to the muscles. As the nerve signals pass through the medulla, they are influenced by nerve impulses from the cerebellum, which controls the fine movements, including those necessary for balance. When alcohol affects the cerebellum, muscle movements become uncoordinated.\
The hypothalamus, pituitary gland and alcohol
The hypothalamus controls and influences many automatic functions of the brain (through the medulla), and coordinates hormonal release (through the pituitary gland). Alcohol depresses nerve centers in the hypothalamus that control sexual arousal and performance. With increased alcohol consumption, sexual desire increases - but sexual performance declines.
By inhibiting the pituitary secretion of anti-diuretic hormone (ADH), alcohol also affects urine excretion. ADH acts on the kidney to reabsorb water, so when it is inhibitted, ADH levels drop, the kidneys don't reabsorb as much water and the kidneys produce more urine.
The medulla and alcohol
The medulla (brain stem) influences or controls body functions that occur automatically, such as your heart rate, temperature and breathing. When alcohol affects the medulla, a person will start to feel sleepy. Increased consumption can lead to unconscious. Needless to say, alcohol's effect on the medulla can be fatal if it is excessive.
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