Tip: Nervous system

The nervous system is capable of perceiving stimuli from the outside world and triggering a reaction if necessary. Its main components are the central nervous system (brain and spinal cord), and the peripheral nervous system, which is divided into the somatic nervous system and the autonomic nervous system. The main faculty of neurons is their ability to be stimulated and to translate impulses. Every neuron of the CNS is connected to countless other neurons. This allows complex reaction patterns such as locomotion or control of the circulatory system to be performed. Somatic nervous system The somatic nervous system is occupied with all conscious control mechanisms and actions. The peripheral part of the somatic nervous system includes thermal, tactile and pressure sensors of the skin, as well as the neurons of all sensory organs. Based upon incoming information collected from these sources, the brain may create a picture of the body’s position as well as its surroundings, and initiate respective movement through muscle stimulation. This process allows your pet to interact with his/her environment. Autonomic nervous system The autonomic nervous system controls mostly unconscious body processes. The dog is not initiating them voluntarily and may influence them only indirectly. Essential body functions such as breathing, heart rate, blood pressure and digestion have to be constantly adapted to changing conditions, i.e. ingestion of food, increased physical activity, sleep, which may occur at any time and in all situations. Even during unconsciousness these processes do not seize. Other organs (i.e. reproductive organs) are also controlled by the autonomic nervous system. It is, evolutionarily, the oldest part of the nervous system. Autonomic nervous system – spinal cord The spinal cord is embedded into the vertebral column of the dog. It starts at the back of the brain and continues downward almost to the tip of the tail. The inside of the spinal cord is white with a gray center. The gray matter contains the bodies of nerve cells, while the white matter contains axons, which are the long, thin projections of nerve cells that lead to and from the brain. The spinal cord is the central relay route of the nervous system. Autonomic nervous system – brain The brain lies protected inside the skull and represents the central control unit of all conscious and unconscious body processes. Even though the brain is smaller than many other body organs it receives the largest amount of the blood in circulation. Three tissue layers are covering the brain protecting it from mechanical insults. The outer most, superficial layer is the dura mater. Underneath the dura mater is the arachnoidea, and subsequently, the pia mater. The brain itself consists of nerve cell bodies and their projections, held together by a type of cell glue. The canine brain can be divided into the following parts: Cerebrum The cerebrum is the largest part of the canine brain, and controls both behavior and emotion. All consciously perceived processes are located here. Acts of association and memory are also performed inside the cerebrum. In contrast to the spinal cord, inside the brain, gray matter is located at the perimeter, while the white matter forms the center. Consciously perceived stimuli are relayed via neuron projections to the cerebral cortex where they are processed, and then transferred to other parts of the brain (cerebrum, brainstem, cerebellum, spinal cord). It is here where actual reaction is initiated. Dogs do not only use inborn behavior patterns, but - like all mammals - have the ability to learn. The "learned" information may be saved and accessed from memory at a later stage. They are considered more intelligent animals, albeit having limited abilities. Like humans they are capable of emotions (sadness, fear, anger) and therefore should be treated with care. Cerebellum The cerebellum is located behind the brain, and rests on top of the brainstem. The majority of all locomotion is coordinated here. In order to orchestrate complex movements i.e. running, leaping or catching, the various groups of muscles involved have to be coordinated precisely. The tonus of the muscles is also maintained by the cerebellum, and allows the body to maintain its equilibrium. Diencephalon (Interbrain) The diencephalon borders the mesencephalon (or midbrain) and projects towards the cerebrum. It consists of a number of layers on top of each other, all occupied with different tasks. The metencephalon serves as a filter preventing information from transgressing into the brain, and thus, to remain unconscious. Control centers for smell, vision, hearing, and sensing are also located here. Another section controls crude motor skills. The most important function of the diencephalon is the control of the autonomic nervous system. This is because all life maintaining functions are controlled and adjusted from here. This includes the maintenance of body temperature, blood pressure, nutrition and water intake, sleep and wake rhythms as well as sexual behavior. Brainstem The brainstem consists of midbrain, pons and the extension of the spinal cord. The midbrain processes optic stimuli and coordinates, amongst other things, the muscles of the eye. The pons connects the cerebrum and cerebellum, and relays crucial information between the two points. The extended spinal cord forms the boundary with the actual spinal cord, and also serves the purpose of passing neuronal stimuli. Additionally, parts of the brainstem control muscle activity, and receive orders from the cerebellum. Autonomic nervous system – brain The brain lies protected inside the skull, and represents the central control unit of all conscious and unconscious bodily processes. Even though the brain is smaller than many other body organs, it receives the largest fraction circulating blood. Three tissue layers are covering the brain protecting it from mechanical insults. The outer most layer is the superficial dura mater, followed by arachnoidea and the pia mater. The brain itself consists of nerve cell bodies and their projections, held together by a type of cell glue. A dogs brain may be divided into the following parts: Cerebrum The cerebrum is the largest part of the dogs brain controlling both behavior and emotions. All processes which are perceived and processed consciously are located here. Association and memory are also stored inside the cerebrum. In contrast to the spinal cord, inside the brain the gray matter is located at the perimeter while the white matter is froms the center. Consciously perceived stimuli are relayed via neuron projections to the cerebral cortex where they are processed and then transferred to other parts of the brain (cerebrum, brainstem, cerebellum, spinal cord). Here is where actual reactions are initiated. Additionally, as dogs do not only use inborn behavior patterns, but - like all mammals - have the ability to learn, it is here where "learned" information may be saved and accessed from memory at a later stage. While dogs have limited abilities, they are considered a more intelligent animal. Like humans, they are capable of emotions such as sadness, fear, and anger, and therefore, should be treated with care. Cerebellum The cerebellum is located behind the brain, and rests on top of the brainstem. The majority of all locomotion is coordinated here. In order to orchestrate complex movements i.e. running, leaping or catching, the various groups of muscles involved are coordinated precisely. The tonus of the muscles allows the body to maintain its balance. Diencephalon (Interbrain) The diencephalon borders the mesencephalon (or midbrain) and projects towards the cerebrum. It consists of a number of layers situated on top of each other, each layer occupied with different tasks. The metencephalon serves as a filter preventing information from transgressing into the brain thus remaining unconscious. Control centers for smell, vision, hearing, and sensing of the dog are also located here. Another section controls crude motor skills. The most important function of the diencephalon is the control of the autonomic nervous system. All life maintaining functions are controlled and adapted from here. This includes the maintenance of body temperature, blood pressure, nutrition and water intake, sleep and wake rhythms as well as sexual behavior. Brainstem The brainstem consists of midbrain, pons and the extension of the spinal cord. The midbrain processes optic stimuli and coordinates amongst other things the muscles of the eye. The pons is connecting cerebrum and cerebellum while relaying crucial information. The extended spinal cord forms the boundary to the actual spinal cord and also serves the purpose of passing neuronal stimuli. Additionally, parts of the brainstem control muscle activity receiving the respective orders from the cerebellum.