Central Nervous System
The central nervous system is the complex of nerve tissues that control the activities of the body and mind. It consists of two parts, the brain and the spinal chord.
Peripheral Nervous System
The peripheral nervous system is the nervous system outside the brain and spinal cord. Its main function is to connect the Central Nervous System to the limbs and organs. In doing this, the Peripheral Nervous System serves as a relay between the brain and spinal cord and the rest of the body.
Somatic Nervous System
The Somatic Nervous System is apart of the Peripheral Nervous System. It is associated with skeletal muscle voluntary control of body movements and consists of sensory (afferent) nerves and motor (efferent) nerves. Its major functions include voluntary movement of the muscles and organs and reflex movements. Also, sensory neurons carry impulses to the brain and the spinal cord in the process of voluntary movement.
Autonomic Nervous System
The Autonomic Nervous System acts largely unconsciously and regulates bodily functions. It is responsible for the control of breathing, heartbeat, heart rate, digestion, etc. Its two main divisions are the sympathetic and parasympathetic nervous systems. The Sympathetic Nervous System's functions are to maintain homeostasis and to stimulate the body's fight-or-flight response. The Parasympathetic Nervous System stimulates body functions such as sexual arousal, salivation, lacrimation, urination, and digestion.
Sensory neurons are nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses. Sensory neurons can also activate motor neurons in order to achieve muscle contraction.
An inteneuron is a neuron that transmits impulses between other neurons. Interneurons create neural circuits, enabling communication between sensory or motor neurons and the central nervous system. They function especially as part of reflexes.
A motor neuron is a nerve cell forming part of a pathway along which impulses pass from the brain or spinal cord to a muscle or gland.
Neuromuscular Junction is a chemical synapse formed by the contact between a motor neuron and a muscle fiber. At the neuromuscular junction, a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction. The function of the NMJ is to transmit signals from the motor neuron to the skeletal muscle fiber quickly and reliably, to ensure precise control of skeletal muscle contraction and voluntary movement.
The Acetylcholine activates muscles in the Peripheral Nervous System. It is also a major neurotransmitter in the Autonomic Nervous System.
Norepinephrine and epinephrine
The Sympathetic Nervous System releases norepinephrine in response to stress. It is classified as a neurotransmitter and can also be referred to as a stress hormone. Epinephrine is a hormone secreted by the medulla of the adrenal glands. When released, it causes an increase in heart rate, muscle strength, blood pressure, and sugar metabolism.
A synapse is a junction between two nerve cells. It consists of a minute gap across which impulses pass by diffusion of a neurotransmitter. Synapse transfers information from one cell to another, siuch as nerve to nerve, or nerve to muscle.
White matter is composed of axons that connect various gray matter areas of the brain to each other, and carry nerve impulses between neurons.
Gray matter contains most of the brain's neuronal cell bodies. It includes regions of the brain involved in muscle control, and sensory perception such as seeing, hearing, memory, etc.
The cerebral cortex is the outer layer of the cerebrum. It is composed of folded gray matter and plays an important role in consciousness. Most information processing in the cerebrum occurs in the cerebral cortex. The cerebral cortex is divided into four lobes, the frontal lobe, parietal lobe, occipital lobe, and temporal lobe. The frontal lobe is for thinking, memory, behavior and movement. The parietal lobe is for language and touch. The occipital lobe is for sight, and the temporal lobe is for hearing, learning, and feelings.
The Limbuc system is a complex system of nerves and networks in the brain. It controls basic emotions and drives, and includes the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus.