The spinal cord can shoot out a reflex command without bothering the brain. The nervous system does more than route information and process commands. Why do certain smells immediately raise particular memories? The answer appears to lie in the limbic system. The limbic system forms two paired rings within the brain, consisting of the hippocampus, the amygdala, the cingulate gyrus, and the dentate gyrus, along with other structures and tracts.
As with other brain segments, the limbic system is involved in multiple nervous system functions and levels of activity. It helps to process both memory and olfaction—our sense of smell—and it manages a range of emotions. The aroma rising from a pot on the stove may send your hand reaching for a spoon. It may also call up a dinner from earlier times, and make you happy, regretful, or nostalgic.
See more from our free eBook library. Cells that Form the Nervous System. Sight, Sound, Smell, Taste, and Touch. Nerves connect the brain and spinal cord to the peripheral nervous system, which is what nerve tissue outside of the central nervous system is called. It is made up of two main parts: the autonomic and the somatic nervous systems.
The autonomic nervous system is part of the peripheral nervous system. One of its main roles is to regulate glands and organs without any effort from our conscious minds.
The autonomic nervous system is made up of two parts: the sympathetic and the parasympathetic. These systems act on the body in opposite ways. Together, they coordinate a multitude of adjustments required for our changing personal needs as we move through our environment.
For example, the size of our pupils is adjusted automatically to allow the correct amount of light into our eyes for optimum vision, our sweat glands are turned on when we get too hot and our salivary glands produce saliva when we eat food or even think about it! The somatic nervous system is also a part of the peripheral nervous system. One of its roles is to relay information from the eyes, ears, skin and muscle to the central nervous system brain and spinal cord. It also obeys commands from the central nervous system and makes muscles contract or relax, allowing us to move.
This page has been produced in consultation with and approved by:. The long-term effects of brain injury will be different for each person and can range from mild to profound. A person with alcohol related brain impairment ARBI might experience problems with coordination, thinking, planning and memory. If a person with alcohol related brain impairment is aware of their memory limits, they can learn how to deal with them.
People with alcohol related brain impairment benefit when their life is organised and follows a good structure. Loss of memory can be temporary or permanent, but 'amnesia' usually refers to the temporary variety.
The nerve fiber is like a wire transmitting impulses through the body. These fibers are covered by a substance called myelin. Myelin protects the nerve fibre and helps the messages go fast through the neurons. When your brain receives that information it elaborates the order of withdrawing the finger. Other nerves bring this message to the muscle of the hand. The result? Hypothalamus: sitting just above the brain stem and roughly the size of an almond, the hypothalamus secretes a number of neurohormones and influences body temperature control, thirst, and hunger.
Thalamus: positioned in the center of the brain, the thalamus receives sensory and motor input and relays it to the rest of the cerebral cortex.
It is involved in the regulation of consciousness, sleep, awareness, and alertness. Amygdala: two almond-shaped nuclei deep within the temporal lobe. They are involved in decision-making, memory, and emotional responses; particularly negative emotions.
The spinal cord, running almost the full length of the back, carries information between the brain and body, but also carries out other tasks. Along its length, it connects with the nerves of the peripheral nervous system PNS that run in from the skin, muscles, and joints. Motor commands from the brain travel from the spine to the muscles and sensory information travels from the sensory tissues — such as the skin — toward the spinal cord and finally up to the brain.
The spinal cord contains circuits that control certain reflexive responses, such as the involuntary movement your arm might make if your finger was to touch a flame. The circuits within the spine can also generate more complex movements such as walking. Even without input from the brain, the spinal nerves can coordinate all of the muscles necessary to walk.
For instance, if the brain of a cat is separated from its spine so that its brain has no contact with its body, it will start spontaneously walking when placed on a treadmill.
The brain is only required to stop and start the process, or make changes if, for instance, an object appears in your path. The CNS can be roughly divided into white and gray matter. As a very general rule, the brain consists of an outer cortex of gray matter and an inner area housing tracts of white matter.
Both types of tissue contain glial cells, which protect and support neurons. White matter mostly consists of axons nerve projections and oligodendrocytes — a type of glial cell — whereas gray matter consists predominantly of neurons. Also called neuroglia, glial cells are often called support cells for neurons. In the brain, they outnumber nerve cells 10 to 1. Without glial cells, developing nerves often lose their way and struggle to form functioning synapses.
The following are brief descriptions of the CNS glial cell types:. Astrocytes: these cells have numerous projections and anchor neurons to their blood supply. They also regulate the local environment by removing excess ions and recycling neurotransmitters. Oligodendrocytes: responsible for creating the myelin sheath — this thin layer coats nerve cells, allowing them to send signals quickly and efficiently.
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