Nervous System

Central nervous system (CNS)

Brain and spinal cord

Peripheral nervous system (PNS)

Paired spinal and cranial nerves carry messages to and from the CNS

Sensory division

Responsible for perceiving both the internal and external environment

Motor division

Responsible for carrying commands to your muscles and glands

Somatosensory

muscles, (mostly skin) - touch, temperature

viscerosensory

internal organs, PH of blood, body temperature, level of O2 in blood

somatic motor

controls skeletal muscles and voluntary movements

visceral motor / autonomic nervous system

controls involuntary muscles, smooth muscles, cardiac muscles

ANS (autonomic nervous system)

sympathetic division, parasympathetic division

sympathetic nervous system

division of the ANS, fight or flight, prepares body for emergencies and heightened activities

ex: increases heart rate and blood flow

parasympathetic nervous system

other division of ANS, called rest and digest division, calms and maintains the body

ex: decreases heart rate and increases digestion

Two main classes of cells

neurons and neuroglial cells

Neurons

generate nerve signals called action potentials

neuroglial cells

supporting cells

neuroglial cells

about a trillion (10^12) neurons in the nervous system, neuroglia outnumber the neurons by as much as 50 to 1

neuroglia cells of the CNS

astrocytes, oligondendrocytes, ependymal cells, microglia

neuroglia of PNS

schwann cells, satellite cells