organization of the nervous system

sensory (afferent) division

• sends signals from senses to CNS

• somatic & visceral

central nervous system

• brain and spinal cord

• integration center

peripheral nervous system

all nerves not found in the brain or spinal cord

motor (efferent) divison

impulses from CNS to muscles or glands

somatic NS

a part of the peripheral nervous system that controls voluntary movements by transmitting signals from the CNS to skeletal muscles.

autonomic NS

a part of the peripheral nervous system that regulates involuntary bodily functions, including heart rate, digestion, and respiratory rate. It is divided into the sympathetic and parasympathetic divisions.

sympathetic divison

fight or flight instincts in emergency situations

parasympathetic division

rest and digest functions

dendrites

receive impulses from sensory organs or other neurons then directs the signal towards the cell body

cell body

• houses all organelles and receives impulses from dendrites

• nissi substances a granular endoplasmic reticulum found in the cell body of neurons, important for synthesizing proteins.

axon

• arises from cone shaped region called axon hillock

• carries signal away from cell body towards axon terminal multiple branches at axon terminal and transmits electrical impulses to other neurons or muscles

nodes of ranvier

gaps in myelin sheath that allow the impulse to travel faster through axon the signal

myelin sheath

insulated layer of lipids, fat produced cells increases and “maintains” the speed/strength of impulses

astrocytes

support and anchor neurons to surrounding capillaries “mop up” leaked K+, recycle neurotransmitters, mitochondria, tissue repair. cns

microgolia

immune response in CNS act as macrophages when needed remove damaged neurons and infections

ependymal cells

cells that line the ventricles of the brain and the spinal cord, producing and circulating cerebrospinal fluid

oligodendrocytes

• similar to schwann cells only in CNS

• produce myelin sheath

schwann cells

• surround nerve fibers in PNS

• produce myelin sheath

satellite cells

• similar to astrocytes

• support and anchor neurons in PNS