The human brain is part of the central nervous system. The brain is protected by the skull on the outside and meninges, a three-layer membrane, on the inside. The average weight of an adult brain is about 3 lbs. An interruption in blood flow to the brain can cause a stroke, which may cause permanent damage to the specific area in which blood flow was interrupted.
Cerebrospinal Fluid
The cerebrospinal fluid serves as a liquid cushion for the brain and spinal cord, supporting and protecting them. The brain monitors the concentration of carbon dioxide in a person’s cerebrospinal fluid. If carbon dioxide is higher than normal, the brain sends a signal to the breathing center in the brain stem to increase respiration to remove excess carbon dioxide.
Cerebrum
The cerebrum is the largest part of a person’s brain. The cerebral cortex is the outermost, visible part of the cerebrum, the part with all the folds. It consists of the right cerebral hemisphere and the left cerebral hemisphere. Each hemisphere is further divided into a frontal lobe, parietal lobe, temporal lobe, occipital lobe and the insula lobe. The cerebral cortex senses touch, temperature, pressure, body position, vision and hearing. Signals to control wrist, hand, finger, ankle and foot movements are generated in the cerebral cortex of the frontal lobe. The cortex also integrates information that enables a person to use language, emotion and memory. The left hemisphere has motor control of the right side of the body and the right hemisphere has motor control of the left side of body. A stroke in the right hemisphere may cause motor issues on the left side of the body.
Cerebellum
The cerebellum is a small part of the brain just below the posterior lobe of the cerebrum. The cerebellum is the fine-tuner of muscle action. For instance, a person’s smooth performance of a biceps curl where the biceps muscles are contracting and triceps muscles are relaxing is possible through the cerebellum. The original signal to move comes from the cerebrum but is coordinated through the cerebellum.
Diencephalon
The diencephalon is not visible from the outside of the brain. It lies in the center of the brain just below the inner part of the cerebrum. A person's thalamus and hypothalamus lie in the diencephalon. The thalamus plays a role in associating sensory information with pleasantness and unpleasantness. The hypothalamus is the link between the nervous system and endocrine system. The pineal gland also lies in the diencephalon. It regulates the secretion of melatonin, a hormone that controls the body's biological clock.
Brain Stem
The brain stem is divided into the midbrain, pons and medulla oblongata. The brain stem provides sensory, motor and reflex functions. The medulla is responsible for reflexes to your heart, blood vessels and lungs. It controls how fast and hard your heart contracts, the diameter of your blood vessels and your breathing rate. Damage to this part of your brain is usually fatal.
References
- “Anatomy & Physiology”; Gary Thibodeau, Ph.D. and Kevin Patton, Ph.D.; 2007
- “First Aid/CPR/AED for Schools and the Community”; American Red Cross; 2006
