Parts of the Nervous System in Cats
The central nervous system includes the spinal cord and the brain. The brain is divided into 3 main sections—the brain stem, which controls many basic life functions, the cerebrum, which is the center of conscious decision-making, and the cerebellum, which is involved in movement and motor control. The spinal cord of cats is divided into regions that correspond to the vertebral bodies (the bones that make up the spine) in the following order from neck to tail: cervical, thoracic, lumbar, sacral, and caudal segments. Specialized tissues called meninges cover the brain and spinal cord, and cerebrospinal fluid surrounds and protects the brain and spinal cord.
The peripheral nervous system consists of the nerves that are found throughout the rest of the body.
Both the central and peripheral nervous systems contain billions of cells known as neurons. Neurons connect with each other to form neurological circuits. Information travels along these circuits via electrical signals.
All neurons have a center portion called a cell bodyand 2 extensions called dendrites and axons. Dendrites receive signals from other neurons and transmit electrical charges to the cell body. Axons transmit the electrical charges away from the cell body. When the current reaches the end of the axon, the axon releases chemicals called neurotransmitters. Neurotransmitters pass the signal to the dendrites of other neurons, or to muscles or glands.
Neurons in the peripheral nervous system combine to form pairs of spinal nerves and pairs of cranial nerves. The spinal nerves arise from the spinal cord and extend axons outward into the front and hind legs and to the bladder, anus, and tail. These nerves subdivide into smaller nerves that cover the entire surface and interior of the body. The cranial nerves include sensory and motor neurons that connect the head and face to the brain.
Types of Neurons
Sensory neurons carry information from the body to the spinal cord or brain stem, and then on to the cerebellum and cerebrum for interpretation. Sensory information includes sensations of pain, position, touch, temperature, taste, hearing, balance, vision, and smell.
Motor neurons carry responses to the sensory information from the spinal cord and brain to the rest of the body. Inside the spinal cord, the axons of motor neurons form bundles known as tracts, which transmit this information to motor peripheral nerves going to muscles in the limbs. Motor neurons are important for voluntary movements and muscle control.
A specialized set of neurons controls and regulates basic, unconscious bodily functions that support life, such as the pumping of the heart and digestion. These neurons make up what is called the autonomic nervous system, which sends axons from the brain stem and spinal cord to various areas of the body, such as the heart muscle, the digestive system, and the pupils of the eyes.
The effects of the mechanism of the disease of the nervous system in cats.
A change in an animal’s ability to sense its environment can be caused by disease in either the central nervous system or the peripheral nervous system. The primary signs of nervous system disorders include behavioral changes, seizures, tremors, pain, numbness, lack of coordination, and weakness or paralysis of one or more legs. The effects of an injury on sensory and motor functions depend on its location and severity.
A spinal cord injury can cause loss of feeling and paralysis below the level of the injury. Mild spinal cord injuries can result in clumsy movement and mild weakness of the limbs. Moderate spinal cord injuries can cause a greater weakness of the limbs. In severe spinal cord injuries, a complete loss of movement (paralysis) and feeling can occur. However, not all spinal cord injuries cause paralysis. For example, injury to the spinal cord in the lower back can result not in limb paralysis but in loss of bladder control.
Brain injuries result in different effects, again depending on which part of the brain is affected. Injuries to the brain stem can cause a loss of balance, weakness of the limbs, hyperactive reflexes, stupor, or coma. Injuries to the cerebellum can result in a lack of coordination of the head and legs, tremors, and a loss of balance. Injuries to the cerebrum can cause complete or partial blindness, loss of the sense of smell, seizures, coma, stupor, pacing or circling behavior, and inability to recognize an owner.
Some injuries to the nervous system can cause damage that is not evident until 24 to 48 hours after the injury occurs. Longterm damage is usually caused by swelling or internal bleeding of the vessels in the brain. Strokes caused by clogged arteries or high blood pressure are rare in pets.