Nervous system

• Neuron or nerve cell -unit of nervous system.
• Neuroglial cells -human nervous system consist of billions of neurons plus supporting cells.
• Cell body (suma) -nucleus and most of the cytoplasm of the neuron is located at it
• Axons -conduct impulses away from the cell body
• Dendrites -conduct impulses toward cell body
• Dendrites -Receive signals from other cells.
• Cell body -Organizes and keeps the cell functional
• Cell membrane -Protects the cell
• Axon hillock -Generates impulse in the neuron.
• Node of Ranvier -Allow diffusion of ions.
• Schwann cells -Produces the myelin sheath, special neuroglial cells located at regular intervals
• Nucleus -Controls the entire neuron
• Axon -Transfers signals to other cells and organs.
• Myelin Sheath -Increases the speed of the signal, secrete a fatty layers over axons
• Axon terminal -Forms junctions with other cells
• Sensory neurons -they conduct sensory information from receptors towards CNS.
• Interneurons -Form brain and spinal cord, they receive information, interpret them and stimulate motor neurons.
• Motor neurons -carry information to muscles or glands, They have many dendrites but only one axon.
• Nerve -union of several axons t are enveloped by a covering made of lipid..
• Sensory nerves: contains the axuns of sensory neurons unly
• Motor nerves: Contain the axons of motor neurons only
• Mixed nerves: Contain the axons of both sensory and motor neurons
• Peripheral nervous system. -composed of nerves and ganglia.
• Ganglion -group of neuron cell bodies in the peripheral nervous system. mass of nerve cell bodies.
• Ganglia -avoid structures containing call bodies of neurons.
• Cranial and Spinal nerves -nerves arise or lead to brain and spinal cord
• Spinal Nerves -31 nerves connecting the spinal wrd and various budy regions
• Central Nervous System -brain and spinal cord
• Brain -Interprets and stores information and sends orders to muscles, glands
• Spinal cord -Pathway connecting the brain and the peripheral nervous system
• Peripheral Nervous System -Transmits information to and from the central nervous system.
• Autonomic nervous system -Automatically regulates glands, internal organs and blood vessels, pupil dilation, digestion, and blood pressure
• Somatic nervous system -carries sensory information and controls movement of the skeletal muscles.
• Parasympathetic division -maintains body functions under ordinary conditions; saves energy
• Sympathetic division -prepares the body to react and expend energy in times of stress
• Sensory system (afferent) -Carries messages from senses to CNS
• Motor system (efferent) -carries messages from CNS to muscles and glands