Download B) Nervous System Introduction NtG Spring

Chapter 7: The Nervous System
Functions of the Nervous System
1. __________________________________________
 Monitor changes occurring _________________________ and ______________________ the body
2. __________________________________________
 Processes and interprets sensory input and decide what to be done
 Mainly occurs in brain and spinal cord
3. __________________________________________
 A response to integrated stimuli by activating effector organs – muscles and glands
Organization of the Nervous System
 Classified based on structure and function
 Structure
 ______________________ ____________________ __________________________
 Function
 Sensory: __________________________________________
 Motor: __________________________________________
___________________________ Classification of the Nervous System
 Central nervous system (_______________)
 Brain and spinal cord
 Integrating and command center
 Peripheral nervous system (________________)
 Cranial nerves and spinal nerves
 Communication lines between the CNS and the rest of the body
____________________________ Classification of the Nervous System
 Peripheral nervous system
 Two subdivisions
 Sensory (____________________________) division
 Carry information _____________________ the CNS
 Motor (____________________________) division
 Carry information _____________________ from the CNS
 Somatic nervous system
 ____________________________ and conscious control
 ____________________________ muscles
 Autonomic nervous system
 ____________________________ and subconscious
 __________________ muscles, ______________ muscles and ______________
 Sympathetic
 ____________________________
 Parasympathetic
 ____________________________
Nervous Tissue
 Two principal types of cells
 Support cells (__________________________)
 Support, insulate and protect the neurons
 Cannot transmit nerve impulses
 Continue to divide
 4 in the CNS and 2 in the PNS
 ________________________
 Structural units of the nervous system
 Transmit electrical impulses from one area of the body to another area using neurotransmitters
Nervous Tissue: Support Cells (neuroglia) in ___________________________
 Astrocytes
 Abundant, star-shaped cells
 ______________________ and ______________________ neurons
 Form barrier and make exchanges between capillaries and neurons
 Control the chemical environment of the brain by cleaning up potassium ions and neurotransmitters
 Microglia
 Small ovoid cells with thorny processes
 Spider-like ___________________________________
 Dispose of debris
 Ependymal cells
 Line central cavities of the brain and spinal cord
 Cells are squamous and columnar shaped and ciliated
 _____________________________ cerebrospinal fluid
 Oligodendrocytes
 Produce ______________________ __________________ (fatty insulation) around nerve fibers
Nervous Tissue: Support Cells in ____________________________
 Satellite cells
 Surround neuron cell bodies located in the PNS
 ____________________________ and ________________________ neurons
 Similar to astrocytes
 Schwann cells
 Surround and form ______________________ _____________________ in the PNS
 Help with regeneration of damaged peripheral nerve fibers
Nervous Tissue: Neurons
 Structural unit of the nervous system
 Highly specialized cells that conduct messages in the form of impulses from one part of the body to another
 Special characteristics
 ____________________________ (about 100 years)
 ____________________________ (cannot divide)
 ____________________________
 Vary in structure but all have a cell body and one or more slender processes
 Plasma membrane is the site of electrical signaling
Major regions of neurons
 Cell body (___________________________)
 Nucleus and metabolic center
 Most are located in the CNS
 Clusters of cell bodies in the CNS are called _________________________
 Lie along the nerves in the PNS are called ___________________________
 Processes (__________________________ and ____________________________)
 Arm like processes that extend from the body of all neurons
 CNS contain both cell bodies and their processes
 PNS consists mainly of neuron processes
 Bundles of neuron processes are called __________________ (CNS) or ___________________ (PNS)
Neuron Processes
 Dendrites
 Main receptive or input region
 ________________________ signals from other neurons
 Conduct impulses ________________________ the cell body

Axons
 Each neuron has only ____________________ axon
 Conducting region of the neuron
 _____________________________ nerve impulses
 Transmits impulses _________________ from the cell body
 Initial region of the axon arises from the ________________ ____________________
 Narrows to form a slender process the rest of the length
 In some neurons the axon is very short and in others it is very long
 Ex: axons of toes extend from your spine to your foot (about 3-4 feet) – the longest cells in your body
Axons and Axonal Terminals
 Axons can branch many times but all end in _________________ ______________________
 Axon terminals
 Knoblike distal endings
 When impulses reaches the terminal it causes ___________________________________ to be released
 Neurotransmitters either ________________________ or __________________________ neurons
 Neurons never touch other neurons
 Separated from the next neuron by a gap
 ________________________________
 Gap between adjacent neurons
Axon Coverings
 Many axons are covered with a whitish, fatty, segmented ________________ ______________
 _________________________
 Covering that protects and insulates the axons and increases the speed of transmission of nerve impulses
 ________________________ ____________________________
 A tight coil of wrapped myelin encloses the axon
 Peripheral nervous system
 Formed by ___________________________ which wrap themselves around the axon in jelly-roll fashion
 Central nervous system
 Formed by ______________________________
 _______________________ of ____________________________
 Adjacent Schwann cells and oligodendrocytes do not touch each other so there are gaps in the myelin
 _______________________________ fibers conduct nerve impulses rapidly
 _______________________________ fibers conduct impulses slowly
Multiple Sclerosis (______________________________)
 Myelin sheath in the CNS are damaged and demyelination occurs
 Affects the ability of nerve cells to communicate with each other
 Caused by an __________________ disease where the body’s own immune system attacks and damages the myelin
 Electrical signals are slowed or stopped from reaching different parts of the body.
 Person loses ability to control his/her muscles
 Cause is unknown and there is no cure
Neuron Cell Body Locations
 Most are found in the ______________________________________________
 White matter
 Dense collections of __________________________ fibers
 Gray matter
 ___________________________ fibers and cell bodies
 Nuclei
 Clusters of cell bodies within the ________________________ matter of the central nervous system
 Outside the CNS
 ________________________: Collections of cell bodies
Neuron Classification
 Neurons classified based on their structure and function
Structural Classification of Neurons
 Multipolar neurons
 Three or more processes
 One axon and the rest dendrites
 Most common neuron type (_____________________ and _____________________________)
 Major neuron type in CNS
 Bipolar neurons
 Two processes
 An axon and a dendrite from opposite sides of the cell body
 _______________________________, found in special sensory organs
 Unipolar neurons
 Have a short single process leaving the cell body
 Mainly found in ______________________________ of PNS (sensory neurons)
Functional Classification of Neurons
 Neurons classified based on the _________________________ the nerve impulse travels in relation to the CNS
 _________________________________________
 _________________________________________
 _________________________________________

Sensory (__________________________________) neurons
 Transmit impulses _______________________________ the CNS
 Sensory receptors in the skin or internal organs
 Cutaneous sense organs (________________________ and ____________________ corpuscles)
 ___________________________ (detect stretch or tension in organs)
 Motor (____________________________________) neurons
 Transmit impulses ____________________________ from the CNS
 Muscles or glands
 Association (____________________________________)
 Found between motor and sensory neurons
 In neural pathways in the CNS
 Make up 99% of the neurons of the body
Amyotrophic lateral sclerosis (ALS) “Lou Gehrig’s Disease”
 Disease of the _________________________ neurons in the CNS that control voluntary movements
 Motor neurons degenerate or die and can no longer send messages to voluntary muscles
 Condition gets worse and usually ends in paralysis and death in about 3-5 years
 Cause is unknown (about 10% are genetic)
 Amyotrophic
 Muscle without ___________________________________
 Sclerosis
 ___________________________________ of tissue