Chapter 18 Flashcards
What is the role of the nervous system?
- communication
- allows the body to work together like a machine
- responsible for behaviors, memories, and movements
What structures and organs make up the nervous systems?
- brain
- spinal cord
- nerves
What are the three functions of the nervous system?
- sensory
- integrative function
- motor
Describe the sensory function.
- senses changes in internal and external environment
- uses sensory neurons
Describe the integrative function.
- analyzes sensory information and makes decisions
- association or interneurons perform this function
Describe the motor function.
- responds to stimuli by initiating action
- uses motor neurons
What are the divisions of the nervous system?
- Central and Peripheral Nervous System
- Afferent and Efferent Divisions
- Somatic and Autonomis Systems
What is the role of the CNS?
- the structural and functional center of the entire nervous system
- integrates incoming pieces of sensory information, evaluate it, and initiate an outgoing response
What is the role of the PNS?
-nerve tissues that lie in the periphery
What structures are part of the CNS?
-brain and spinal cord
What structures are part of the PNS?
-cranial and spinal nerves
What type of information is sent afferently?
-incoming sensory pathways
What type of information is sent efferently?
-outgoing motor pathways
What are the target structures of the somatic nervous system?
- carry information to the skeletal muscles
- receives information from the somatic sensory division
What are the target structures of the autonomic nervous system?
- carry information to the visceral effectors
- involuntary
What are two types of autonomic responses?
- sympathetic (fight or flight)
- parasympathetic (rest and digest)
What is the enteric nervous system? What is unique about it?
- the second brain
- in the wall of the gut
- can act somewhat independently
What are glia?
- cells that support the function of neurons
- maintain their ability to divide throughout adulthood
What are the neuroglia of the CNS?
- astrocytes
- microglia
- ependymal cells
- oligodendrocytes
What are the neuroglia of the PNS?
-schwann cells
What is the function of astrocytes?
- attach neurons to tiny blood capillaries in the brain
- this feeds the neurons by picking up glucose in the blood
- coordinate the production of new neurons
- contribute to blood brain barrier
What do astrocytes look like?
-star shaped cells
What is the blood brain barrier? Function?
- a double barrier made up of astrocyte feet and endothelial cells
- prevents large molecules to pass through and enter the blood stream
Why is the blood brain barrier clinically important?
-it is difficult for brain disorder treatments to work
What are microglia? Function?
- cells that engulf and destroy microorganisms and cellular debris
- phagocytosis
What are ependymal cells? Function?
- cells that form sheets that line fluid-filled cavities in the brain and spinal cord
- produce fluid
What unique cell process do ependymal cells have?
-contain cilia that helps circulate fluid
What are oligodendrocytes? Function?
- cells that produce a fatty myelin sheath around nerve fibers
- help hold nerve fibers together
What are schwann cells? Function?
- cells that use themselves to wrap around a single nerve fiber
- nodes of ranvier
What is a satellite cell?
-surrounds the cell body of a neuron
Describe the differences between myelinated and unmyelinated.
- myelinated: white matter, wrapped with cells
- unmyelinated: grey matter, just held together, not wrapped
What is the structure of a neuron?
- soma
- axon
- dendrites
What is the cell body and what do you find inside?
- middle part
- contains the nucleus, cytoplasm, nissl bodies, and neurotransmitters
What are dendrites and what is their function?
- branch extensions from the body that has many receptors
- receive stimuli and conduct electrical signals toward the cell body
What is the axon and what is their function?
- single process from the bottom of the soma
- conducts impulses away from the cell body
How does diameter and myelination relate to the speed of an electrical impulse?
-the larger the diameter the more rapid the conduction
How does the cytoskeleton contribute to the function of the neuron?
-the microtubules form a railway for the rapid transport of small organelles to and from the far ends of the neuron
What are the three structural types or neurons? Describe
- multipolar
- bipolar
- unipolar
What are the three functional types of neurons? Define
- afferent
- efferent
- interneurons
Where do you find interneurons?
-in a three neuron arc
What is a reflex arc?
- a signal conduction route to and from the CNS
- like a regulatory feedback loop
What is a three neuron arc?
- the afferent neuron detects something like stepping on a nail
- it goes up to the integrator and the interneuron
- switches to the other side of the brain
- the efferent neuron tells the opposite leg to hold and support all the body’s weight
What is a two neuron arc?
-when the doctor hits you knee with a hammer and your leg kicks
What is a synapse?
-the place where the nerve information is transmitted from one neuron to another
What is a nerve?
-bundles of peripheral nerve fibers (axons and dendrites) that connect different regions of the nervous system
What is the structure of a nerve?
- endoneurium: surrounds the schwann cells
- perineurium: surrounds bundles of nerve fibers; makes a fascicle
- epineurium: surrounds many fascicles; the deep part separates each fascicle
What is a tract?
-bundles of nerve fibers
How are nerves different from tracts?
- tracts do not have connective tissue coverings
- tracts are in the spinal cord and brain
What is white matter?
- myelinated
- tracts and nerves
What is gray matter?
-unmyelinated
What do you call collections of cell bodies in the CNS and PNS?
- Nuclei in CNS
- Ganglia in PNS
How are nerves repaired?
- myelin and axon break into droplets
- WBCs phagocytose droplets
- axonal sprount enters damaged area
- Schwann cells form new myelin sheaths
Why is it hard for nerves to be repaired?
- only occurs when damage is not extensive
- soma and neurilemma are still intact
- scarring cannot have occured
