ANAPHY

• Central Nervous System composed of the brain and spinal cord
• Peripheral Nervous System composed of cranial and spinal nerves
• Sensory Division or Afferent Division conducts action potentials from sensory receptors to the CNS.
• The neurons that transmit action potentials from the periphery to the CNS are called SENSORY NEURONS.
• Motor Division or Efferent Division conducts action potentials from the CNS to effector organs, such as muscles and glands.
• The neurons that transmit action potentials from the CNS toward the periphery are called MOTOR NEURONS.
• Somatic nervous system transmits action potentials from the CNS to skeletal muscles
• Autonomic nervous system transmits action potentials from the CNS to cardiac muscle, smooth muscle, and glands.
• Enteric Nervous system is a unique part of the peripheral nervous system and has both sensory and motor neurons contained wholly

  within the digestive tract
• Cell body contains a single nucleus. Nucleus is the source of information for gene expression. Contains rough endoplasmic reticulum, Golgi bodies, mitochondria and lysosomes
• Dendrites are short, often highly branched cytoplasmic extensions that are tapered from their bases at the neuron cell body to their tips
• Dendrites receive information from other neurons or from sensory receptors and transmit the information toward the neuron cell body
• Axon is single long cell process extending the neuron cell body. The area where the axon leaves the neuron cell body is called AXON HILLOCK.
• Action potential are impulses, exist across the membranes of essentially all cells of the body. These impulses can be used to transmit signals along the cell membranes
• Glial cells/Neuroglia are the primarily supportive cells of the CNS and PNS, meaning these cells do not conduct action potentials.
• Astrocytes serve as the major supporting cells in the CNS. Can stimulate or inhibit the signaling activity of nearby neurons. Participate with the blood vessel endothelium to form a permeability barrier, called the blood-brain barrier, between the blood and the CNS.
• Ependymal cells line the fluid-filled cavities (ventricles and canals) within the CNS.
• Some ependymal cells produce cerebrospinal fluid, and others, with cilia on the surface, help move the cerebrospinal fluid through the CNS.
• Microglia act as immune cells of the CNS. They help protect the brain by removing bacteria and cell debris
• Oligodendrocytes provide an insulating material that surrounds axons in

  the CNS
• Schwann cells provide an insulating material that surrounds axons in the PNS
• Myelin sheaths are specialized layers that wrap around the axons of

  some neurons. Axons with these myelin sheaths are called myelinated axons.
• Gaps in the myelin sheath, called nodes of Ranvier occur about every

  millimeter between the oligodendrocyte segments or between individual

  Schwann cells.
• Spinal Cord extends from the foramen magnum at the base of the skull to the second lumbar vertebra
• The inferior end of the spinal cord and the spinal nerves exiting there are

  called the Cauda equina.
• Ascending tracts consist of axons that conduct action potentials toward the brain.
• Descending tracts consists of axons that conduct action potentials away from the brain
• Central canal is a fluid-filled space in the center of the spinal cord
• Lateral horn exist in levels of spinal cord associated with autonomic

  nervous system (interneurons)
• Dorsal horns (posterior) combined dorsal rootlets on the dorsal side of the spinal cord at each segment (sensory neurons)
• Ventral horns (anterior) combined ventral rootlets on the ventral side of the spinal cord (cell bodies of motor neurons)
• The neuronal cell bodies of the dorsal root are located in an enlarged area called DORSAL ROOT GANGLION.
• Reflex is an involuntary reaction in response to a stimulus applied to the

  periphery and transmitted to the CNS.
• Reflex Arc is the neuronal pathway by which a reflex occurs.
• Reflex Arc is the basic functional unit of the nervous system because it is the smallest, simplest pathway capable of receiving a stimulus and

  yielding a response.
• Major Regions of the Brain: Brainstem, Cerebrum, Diencephalon, Cerebellum.
• Brainstem connects the spinal cord to the remainder of the brain
• Brainstem consists of the medulla, pons and

  midbrain
• Brainstem contains several nuclei involved in vital body functions, such as the control of heart rate, blood pressure and breathing.
• Medulla Oblongata is the most inferior portion of the brainstem. Contains discrete nuclei with specific functions, such as regulation of heart rate and blood vessel diameter, breathing, swallowing, vomiting, coughing, sneezing, balance, and coordination.