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Chapter Nine; Nervous System (meninges (Three Layers of Meninges (third,…
Chapter Nine; Nervous System
meninges
meninges are protective covering of both brain and spinal cord
meninges help to set up layer that act as cushioning and shock absorbers for the brain and spinal cord
Three Layers of Meninges
third, innermost layer
fused to neural tissue, is pia mater, containing blood vessels that serve brain and spinal cord
middle layer is wispy delicate layer resembling spider web called arachnoid mater, composed of collagen and elastic fibers acting as shock absorber and transporting dissolved gases and nutrients as well as chemical messengers and waste products
outer layer
thick fibrous tissue called dura mater
between dura mater and vertebral column is space filled with fat and blood vessels called epidural space
between dura mater and arachnoid mater is subdural space filled with tiny bit of fluid
between arachnoid and pia mater is large sybdural space filled with CSF that acts as fluid cushion
They also transport dissolved gases and nutrients as well as chemical messenger and waste products since there is no blood in the cns its self
these three membranes and their fluid filled spaces, together with bones of skull and verterbral column, form strong protective system against CNS injury
Horns
Dorsal horn
involved in sensory function
ventral horn
involved in motor function
lateral horn
dealing with automatic functions
Amyotrophic lateral
rapidly progressive, fatal degeneration of the motor system
5 years of diaimessis results in death
begins to 40 or 60 years old
symptoms muscle weakness, twitching, cramping, difficulty in speaking and swallowing
nervous system
is complex and important to body's control
nervous system monitors conditions and takes corretice ciction, when necessary to keep everything running smoothing
control system, the body, nervous, endocrine systems, receives help, special senses
large complex, sometimes difficute, understand
systems themselves are complex and vital systems
brain stem is stalk-like structure inferior to and partially covered by, cerebrum
divided into three sections
medulla oblongata
continuous with spinal cord, responsible for impulses that control heart beat respiration and blood vessel diameter. reflex center for coughing, sneezing, swallowing and vomitting
pons
just superior to medulla oblongata and it plays a role in breathing
midbrain
most superior portion of brain stem and is completely covered by cerebrum
the brainstem contains reticular system, diffuse network of brainstem neurons responsible for "walking up" cerebral cortex
general anesthesia inhibits reticular system causeing unconscious
injury to reticular system can lead to coma
brain stem recieves sensory information and contains control systems for vital process such as blood pressure heart rate and ventilation
basic operations
brain and spinal cord are central nervous control total nervous system
everything outside brain and spinal cord is part of peripheral nervous system
input side of nervous system is sensory system
takes everything in and brings it to the nervous system
outside of nervous system is nerve systems
somatic nervous system controls skeletal muscle and mostly voluntary movement
motor system
somatic nervous system
controls skeletal muscle and voluntary movement
autonomic nervous system
controls smooth cardiac muscle in your organs and several glands
involuntary and not underconcious control
can be further divided into parasympathere and sympathetic nervous system
CNS four types of glial cells
microgilia removes debris and microbes
oligodendrocytes
hold nerve fibers together and make lipid insulation called myelin
specialized cells in nervous system called neruroglia or glial cells, perform specialized functions
neurons specific functions
body
cell metabolism
dendrites
recieve information from the enviroment
axon
generates and sends signal to other cells
where signal leaves cells
synapse
where axon terminal and recieving cell combine
how neurons work
neurons are called excitable cells
each time change particles flow across cell membrane there is tine charge generated
spinal cord and spinal nerves :
meninges are protective covering of both brain and spinal cord
menings help to set up layers that act as cushioning and shock absorbers for the brain and spinal cord
three columns
columns
area o white matter (contains axon running up and down spinal cord, to form brain) act as nerve tracts pathways
ascending pathways
carry sensory information up to brain
dorsal column tract
carries fine touch and vibration information to cerebral cortex
descending pathways
carry motor information (voluntary movement) down/from the brain
corticospinal tract
carries order from brain to motor neurons in ventral horn and spinal cord
coricobular tract
carries orders from brain to motor neurons in brain stem
reticulospinal
rubrospinal tract
carry information which helps coordinate movement from brain to brainstem and ventral horn of spinal cord