nervous system Flashcards
CNS (parts, protection, function)
central nervous system
parts-brain and spinal cord
protection-encased by bone
function-processes info and acts as the integrating and command center- interprets sensory info and sends out instructions based on past experiences and current conditions
tracts
bundles of nerve fibers
PNS (parts, protection, function)
peripheral nervous system
parts-anything on the perimeter of the CNS- 12 pairs of cranial nerves and 31 pairs of spinal nerves
protection- bundled together by connective tissue
function- afferent and efferent
afferent
sensory
- transmits action potentials that travel to the CNS
- keeps the brain informed
somatic messages
from the skin, skeletal muscles, or joints
visceral messages
from internal organs
efferent (branches?)
- transmits action potentials that travel away from CNS
- carries out the choice from the brain to body
- 2 branches- somatic and autonomic
somatic
- voluntary movements
- CNS to skeletal muscles
autonomic (branches?)
- involuntary movements
- CNS to smooth or cardiac muscle and glands
- regulates automatic events
- 2 branches- sympathetic and parasympathetic
sympathetic nervous system
- most active during physical activity
- “fight or flight”
parasympathetic nervous system
- regulates resting functions
- “rest and digest”
nervous tissue
-made of neuroglia and neurons
neuroglia (function)
- “nerve glue”
- support and protect neurons
- make up more than half of the brain’s weight
- mitosis (responsible for brain tumors)
nerves (functions)
- receive stimuli, conduct action potentials, and transmit signals to other neurons
- amitotic
resting neurons
- polarized (higher concentration of Na+ outside and higher concentration of K+ inside the cell)
- -70 mV charge
Na+/ K+ pump
-maintain the distribution of Na+ and K+
how are nuerons fired
- dendrites stimulated
- Na+ gates open to allow Na+ to flood in (depolarization- more positive)
- causes graded potential cause its getting stronger
- graded potential reaches axon hillock at -55mV which causes an action potential (nerve impulse)
- Na+ gates ate opened causing a change from -55 to 30mV
- action potential reaches the terminal and triggers the Ca+ gates to cause the terminal to release neurotransmitters into the synaps through exocytosis
- repolarization is K+ flooding the cell to regain the -70 mV charge
axon hillock
-where the axon joins the cell body
axon terminals
- synaptic terminals, synaptic knobs, synaptic boutons.
- play role in communication with another cell
dendrites
- extend out from the cell body
- intercellular communication.
- receives info
synapse
- specialized site where the neuron communicates with another cell
- synaptic cleft separates the 2 cells
presynaptic cell
-sends message and includes axon terminal, typically a neuron
three types of neurons
- bipolar nuerons
- unipolar nuerons
- multipolar nuerons
bipolar nuerons
- 2 extensions from cell body
- special sense organs
- small
- optic and auditory sensory
- least common
unipolar nuerons
- 1 extension from cell body
- dendrites and axon are continuous
- cell body lays off to the side
- sensory neurons
- long, end at synapses in CNS
multipolar nuerons
- 2 or more dendrites
- most common in CNS
- motor and association neurons
interneurons
- located between sensory and motor neurons
- most common
- most located within brain and spinal cord
- distribute sensory info and coordinate motor activity
resting membrane potential
- -70 in neurons
myelin
-protects and electrically insulates axons from one another
nodes of ranvier
- gaps between each myelin sheath
- increases speed of nerve impulse conduction
saltatory conduction
-impulses jump from node to node due to myelin
how does communication between PNS and CNS occur
- afferent nerves enter the dorsal horn
- message goes up the spinal cord (sensory tracts) to the brain
- brain makes a choice
- efferent nerve tract carries command down the spinal cord
- exits out the ventral horn
reflex arc
- rapid, predictable and involuntary response to stimuli
- receptor recieves stimuli
- message goes up the afferent pathway to dorsal horn
- message transferred to ventral horn (help of association neuron)
- travels down efferent pathway and causes a reaction
- afferent message travels to brain but after action
cerebrum
- largest part of brain
- surfaces are folded and covered by a neural cortex called the cerebral cortex.
- forms elevated ridges (gyri )
- separated by shallow depressions called sulci or by deeper grooves called fissures
- conscious thoughts and all intellecutal functions originate in the cerebral hemispheres
- processing somatic sensory and motor information
- sends info to oppositie side of body
longitudinal fussure
-deep groove down the middle of the cerebral hemispheres
corpus callosum
-connection of nerve fibers between the hemispheres
frontal lobe
- output center
- functions-problem solving- personality- voluntary motor control
- broca’s area
broca’s area
speaking ability (left hemisphere)
parietal lobe
- input lobe
- -functions- recesses and evaluates sensory info, but not smell, hearing, or vision- understand speech- ability to use words
- integrate and interpret sensations
- storage of memories of sensory experiences
occipital lobe
- input lobe
- visual area
- functions- recognize objects visually- combine images
temporal lobe
- input lobe
- functions- receives and evaluates inpot for smell and hearing
- wernicke’s area
wernicke’s area
- understand oral/ written words
- in the temporal lobe
cerebellum
- second larges part of brain
- attached to brain stem
- functions- controls coordination of muscles- regulates posture and balance
arbor vitae
-white matter of the cerebellum
diencephalon
- grey matter
- found between brainstem and cerebrum
thalamus
- gateway to the cerebrum
- relays incoming info to the cerbral cortex and outgoing motor impulses to their destinations
hypothalamus
-regulates autonomic functions (sleep, hunger, thirst, etc)
brain stem
-pons and medulla oblongata
pons
- “bridge”
- nerve fiber tracts that connect the brain
medulla oblongata
- controls bital functions (brathing, heart beat, blood pressure, etc)
- found under the pons and ends at the foramen magnum
foramen magnum
- where spinal cord ends
- injury here could cause quadriple gia
spinal cord
- extends from foramen magnum to end of first lumbar vertebrae
- take messages to and from brain
- end of spinal cord is the conus medullaris
conus medullaris
- names due to cone shape
- end of spinal cord
meninges
- protects the brain and spinal cord
- dura mater
- arachnoid
- pia matter
dura mater
- “tougher mother”
- thickest and toughest
- epidural space- space superficial to the dura mater and deep to the vertebra and skull bones
arachnoid mater
- looks like spider web
- subarachnoid space- space between arachnoid mater and pia mater
- blood vessels and cerebral spinal fluid can be located here
pia mater
- “gentle mother”
- lies directly on top of the brain and spinal cord
menengitis
- inflammation of the meninges
- a virus or bacteria can cause this
- could be life threatening (spread to CNS)
ependymal cells
-lines hollow fluid filled spaces
Astrocytes
-regulate the external chemical environment of neurons by removing excess ions
Oligodendrocytes
cells that coat axons in the central nervous system (CNS) with their cell membrane, forming a specialized membrane differentiation called myelin
Satellite cells
- small cells that surround neurons in sensory, sympathetic, and parasympathetic ganglia
- regulate the external chemical environment
