Central Nervous System

CNS

• 2% of animal's weight
• contains 15% of blood volume
• uses 20% of all oexygen
• uses 50% of all glucose
• brain and spinal cord: encased in bone
• has interneurons
• processes, integrates, stores and responds to info from PNS

PNS going to CNS

involves sensory neurons

Peripheral Nervous System

PNS

• is the nervous tissue outside of CNS
• consists of sensory receptors and nerves
• detects stimuli and transmits info to the CNS and receives info from CNS
• 2 divisions: sensory and motor

• conducting zone
• extension of plasma membrane
• typically single
• send signals

• Output zone
• convey electrical or chemical message to other cells
• Ca2+ enters here through open channels and bind to synaptic vessicles
• here synaptic vesicles fuse w/ membrane and release neurotransmitter

• In CNS
• cell bodies of neurons involved in a similar function
• similar to ganglion of PNS 

• In PNS
• structure is cell bodies of neurons involved in similar functions

• Similar to nucleus of CNS

• in CNS
• myelinated axons that run in parallel bundles
• analogous to the nerve in PNS

• in PNS
• myelinated axons that run in parallel bundles
• analogous to the tract in CNS

• part of the PNS that carries action potentials away from the CNS in cranial or spinal nerves
• 2 divisions: somatic nervous system and autonomic nervous system

• part of the motor division of the PNS
• innervates cardiac muscle, smooth muscle and glands
• 3 divisions
• is a balance between activity of the sympathetic and parasympathetic branches
• is essential for normal homeostasis of many physiologic systems
• nerves here contain both afferent and efferent fibers

part of the autonomic nervous system (ANS)

is most active during physical activity(fight or flight)

Part of the autonomic nervous system (ANS)

regulates resting functions (rest and digest division)

part of Autonomic nervous system

controls the digestive system

• detect info from the outside world or internal body conditions
• afferent neurons transmit to CNS

• send signals AWAY from CNS to elicit response
• efferent transmit away from CNS

• small cells of the CNS with spiny processes
• immune cells, scavenging invaders and debris
• have phagocytes that monitor the health of neurons

• support cells of the CNS
• most abundant, versatile and highly branched
• make up the blood-brain barrier
• guide migrations of neurons
• mop up leaked potassium(K) ions recycling neurotransmitters
• supply energy sources for neurons (glycogen, lactate) in the metabolism

produce myelin that covers the neurons

cell of the CNS

• produces the cerebrospinal fluid (CSF)
• lines the brain ventricles and central canal of the spinal cord
• cells of the CNS

• extensions of plasma membrane
• may be single or branching
• incoming signals

a.k.a. the cell body

contains nucleus and organelles

• fatty(protein lipid), sheath around most long axons
• protects the axon
• electrically insulate axons
• increase the speed of nerve impulse
• "white matter

• passive transport
• gases and a few small, uncharged molecules can passively diffuse across

• passive transport
• rate of diffusion depends on chemistry of solute and its concentration

• selectively permeable- only some solutes can cross
• their function is to compartmentalize

Na+/K+-ATPase

fixed anions in the cell

proteins in the cell

communication

coordinating activity of tissues

sensing the environment

provides passive energy for transport of nutrients across membranes

allows for nerve impulses (action potentials)

allows for muscle contraction