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AP Exam 1: Nervous System
Both CNS and PNS
26
Biology
Undergraduate 3
09/30/2015

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Term
CNS
Definition

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 

 

Term
Sensory Neurons
Definition

(Afferent of PNS) 

-Sends info to CNS

-Monitors internal environments (visceral sensory neurons)

-Monitors the effects of external environments 

 

Term
Three Types of Sensory Receptors
Definition

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 

 

Term
Motor Neurons
Definition

(Efferent Neurons from CNS)

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

OR

via Autonomic Nervous System (involuntary) 

Term
Interneurons
Definition

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 

Term
Axon of Neurons and its Axoplasm
Definition

Long, carries electrical signal (action potential) to target

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

Term
[image]
Definition

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) 

Term
PNS
Definition
Peripheral Nervous System includes all neural tissue outside the CNS delivers sensory information to CNS and carries out motor commands to peripheral tissues and systems
Term
Afferent vs Efferent Divisons of the PNS
Definition

1.  Afferent carries sensory information from PNS TO CNS

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

Term
Efferent Divisions: SNS vs. ANS
Definition

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) 

Term
Receptors (Afferent Division)
Definition

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

 

 

Term
[image]
Definition

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) 

 

Term
Syanpse
Definition

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 

Term
Synaptic Knob and Neurotransmitters
Definition

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 

Term
Axoplasmic Transport
Definition

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 

Term
Major Organelles in a Neuron's Cell Body
Definition

-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

Term
Neuroglia
Definition
Supporting and protecting cells of the neurons by preserving physical and biochemical structure of neural tissue and are essential to the survival and function of neurons
Term
Four Types of Neuroglia in the CNS
Definition

1. Ependymal Cells 

2.  Astrocytes

3. Oligodendrocytes 

4. Microglia 

Term
Ependymal Cells
Definition

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 

Term
Astrocytes
Definition

(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 

Term
Oligodendrocytes
Definition

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

 

Term
Myelin/Myelination/White Matter
Definition

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 

Term
Microglia
Definition
Phagocytic cells that migrate through the CNS cleaning up cellular debris, waste products and any pathogens
Term
Neuroglia in the PNS
Definition

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)

Term
Wallerian Degeneration
Definition
Axon degenerates and macrophages migrate to clean debris.  Schwann cells proliferate and form a solid cord that wraps around the injured axon.  Occurs primarily in PNS
Term
Limited Regeneration in CNS...Why?
Definition

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

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