Central Nervous System consists of brain and spinal cord, contains neural tissue, connective tissues, and blood vessels and are to process and coordinate sensory data, motor commands, and higher functions of brain 

(Afferent of PNS) 

-Sends info to CNS

-Monitors internal environments (visceral sensory neurons)

-Monitors the effects of external environments 

1.  Interoceptors: Monitor internal systems and internal senses (taste, digestion, cardiovascular, pain)

2.  Exteroceptors: Monitor external senses and distance senses (touch, temperature, sight, smell, hearing)

3.  Proprioceptors: Monitor position and movement of the skeletal muscles/joints 

(Efferent Neurons from CNS)

Efferent fibers (axons) travel to PNS via Somatic Nervous System (voluntary) 

OR

via Autonomic Nervous System (involuntary) 

Mostly located in the brain, spinal cord and autonomic ganglia

Respsonsible for distributing sensory information and coordinating motor activity 

Involved in higher functions such as learning, memory and planning 

Long, carries electrical signal (action potential) to target

Axoplasm is its cytoplasm that contains neurotubules, neurofibrils, enzymes, and organelles (vesicles, mitochondria, lysosomes) 

1.  Dendrites: 80-90% of the surface area of neuron, receive information from other cells 

2.  "Gray Matter" nissil bodies dense with RER and ribosomes 

3. Soma/Cell Body 

4. Axolemma: Cell membrane that covers axoplasm

5.  Axon

6. Telodendria (at their ends is the axon terminal) 

1.  Afferent carries sensory information from PNS TO CNS

2.  Efferent divisions carries out motor cammands from CNS to PNS muscles and glands

Both are effectors which respond to efferent signals by doing something: 

-SNS (Somatic): Muscle contractions both voluntary and involuntary 

-ANS (Autonomic): Subconcious contractions of smooth muscle, cardiac muscles and glandular secretions 

(Sympathetic: Stimulating effect)
(Parasympathetic: Relaxing effect) 

Detect changes or respond to stimuli, can be  neurons and other specialzed cells or complex sensory organs like eyes and ears

A. Anaxonic: all processes are dendrites, no axon (brain and sense organs)

B.  Bipolar: two processes separated by cel body(sight, hearing, smell) 

C.  Unipolar: single, elongated process, cell body to the side (SENSORY of PNS)

D. Multipolar: more than two processes, single axon and multiple dendrites (MOTOR in CNS) 

Where a neuron communicates with another cell: 
Presynaptic cell: Sends the message via its axon terminal

Postsynpatic cell: receives message via its dendrites

Synaptic Cleft: gap that separates the membranes

Neuromuscular and Neuroglandular junctions 

Cytoplasmic, elongated portion of the axon that contains synaptic vesicles of neurotransmitters 

Neurotransmitters are chemical messegners that are release by the presynaptic membrane and received by the postsynaptic membrane. 

Broken down by enzymes and reassmbled at the synaptic knob 

Movement of materials between the cell body and axon terminals.  

Neurotubules within the axon transport raw material between the cell body and the synaptic Knob powered by mitochondria in two directions: 
Aneterograde: powered by Kinesin moves material from cell body to axon

Retrograde: Powered by Dinesin moves material from the axon to cell body 

-Large nucleus and nucleolus 

-Perikaryon (cytoplasm) has a rough/grainy appearance due to the RER and free ribosomes, helps sysnthesize orangic material 

-RER and ribosomes synthesize proteins and produces neurotransmitters 

-Numerous mitochondria to meet the high energy requirements of an active neuron

-Cytoskeleton of neurofilaments, neurotubules, and neuronfibrils

1. Ependymal Cells 

2.  Astrocytes

3. Oligodendrocytes 

4. Microglia 

Highly branched and contact the neurglia directly

Form Epithelium called Ependyma

Line the central canal of spinal cord and ventricles of brain

Secrete CSF (cerebrospinal fluid): 

cilia/microvilli circulate CSF continuously, monitors the CSF, contains stem cells for repair, CSF provides protective cushion and transports dissolved gases, nutrients, waste and other materials 

(largest and most numerous) 

1. Maintain the blood-brain barrier (isolates the CNS from general circulation so neurons aren't affected by hormones, amino acids or other chemicals in the blood)

2. Creates a 3-D framework for CNS via microfilaments to provide a structual framework for neurons of brain and SC

3. Repairing Damaged Neural Tissue: can make structural repairs that stabilize tissue

4.  Guide Neuron Development

5.  Control the Interstitial Environment: Regulating ion concentrations, provding a rapid transit system, controlling blood flow, absorbing neurotransmitters, releasing chemicals that enhance (or suppress) communication 

Helps to form the Myelin sheath along the length of the axon.  

Myeline is the membranous wrapping that serves as electrical insulation and icrease the speed at which an action potential travesl the axon and are formed from oligodendrocytes.  

White Matter: regions of CNS that are covered in Myelin sheaths (Internodes)

Nodes: gaps between internodes 

1.  Satellite Cells (aka amphicytes): surround the ganglia and regulate the environment around these neurons 

2.  Schwann Cells (aka neurilemmocytes): form a myelin sheath around peripheral axons; 1 Schwann cell can sheath only one segment of an axon (many schwann cells needed to sheath entire axon)

1.  More axons are likely to be involved in injury 

2.  astrocytes produce scar tissue that can preven axon growth

3.  Astrocytes release chemicals that block regrowth of axons