integrate incoming signals that Contains an abundance of mitochondria, fixed and free ribosomes and RER (Nissl bodies), but lack centrioles

• Act as ‘receptors’
• Extend out from the cell body and branch into dendritic spines; account for 80-90% of the total surface area of a neuron

• Propagates electrical impulses known as action potentials

Initial segment, Axon collaterals, Telodendria, Synaptic knob

joins the cell body at the axon hillock

branches of an axon; enable communication with more than one cell

terminal, finger-like projections of the axon

at the end of a telodendrion; contain vesicles full of neurotransmitters

• Presynaptic neuron

• Postsynaptic neuron

• Neuromuscular junction

• Neuroglandular junction

Roughly 10 million sensory neurons transmit electrical impulses along afferent fibers from sensory receptors in the PNS into the CNS

Cell bodies in collections outside of the CNS

monitor respiratory, digestive, cardiovascular, reproductive, and urinary systems; deep pressure, distension and pain

monitor stimuli from outside the body, i.e. pressure, temperature, touch, smell, vision, hearing, taste and equilibrium

monitor position and movement of skeletal muscles and joints

Roughly 500,000 motor neurons transmit electrical impulses along efferent fibers from the CNS through the PNS to effectors (i.e. muscle, glands, adipose tissue)

Cell bodies in collections inside of the CNS

Roughly 20 billion, most of which are found in the CNS

• Distribute sensory input and coordinate motor output

Somatic and Visceral

signals from receptors in skin, muscle, and joints

signals from receptors in heart, lungs, digestive organs, bladder

Somatic and Visceral (autonomic)

signals to skeletal muscles for voluntary contraction and involuntary somatic reflexes

signals to glands, cardiac, and smooth muscle; primarily involuntary:

• Sympathetic: fight or flight division
• Parasympathtic: rest and digest division