intro to nervous system (4a) Flashcards
what are the functions of the nervous system
detecting sensory stimuli/input
integrating sensory imput
deciding if motor output is necessary
what are examples of sensory input
pressure, taste, sound, light, blood pH, hormone levels
was is a visceral sensory pathway
stimulus that is detected involuntarily (change in blood pH, organ pressure sensors)
what is motor output
electrochemical signal that is transmitted to organs from the central nervous system that is converted into some form of action
examples of motor output
movement
change in heart rate
release of hormones
sweating
release/storage of glucose
what are the components of the nervous system
the central nervous system: brain and spinal cord
the peripheral nervous system: cranial and spinal nerves
what are the functions of the brain and spinal cord
integration of information
interprets sensory information
sends outgoing instructions
what are the functions of spinal and cranial nerves
carry impulses to and from spinal cord/brain
communication lines among sensory organs, brain and spinal cord and glands/muscles
what is the sensory/afferent division and what are its components
nerve fibers that carry information to CNS
somatic sensory
visceral sensory
what is the somatic sensory division
fibers that carry information from the skin, skeletal muscles and joints
what is the visceral sensory division
fibers carry information from visceral organs (ventral cavities)
what does somatic refer to regarding voluntary/involuntary control
somatic means voluntary control is present
what is the motor/efferent division and what are its components
nerve fibers that carry impulses away from the CNS to effector organs (muscles and glands)
somatic nervous system
autonomic nervous system
what is the somatic nervous system
system that controls skeletal muscles (voluntary)
what is the autonomic nervous system and its components
system that controls smooth and cardiac muscles and glands (involuntary)
divided in sympathetic and parasympathetic nervous systems
what is the one organ made of skeletal muscles that is not voluntary control
diaphragm
what are the four types of neuroglia in the CNS
astrocytes
microglial cells
ependymal cells
oligodendrocytes
what is the structure and function of astrocytes
star shaped
anchor neurons to blood capillaries and mediate exchanges between them
provides nutrients to neurons (glucose)
absorb excess potassium and neurotransmitters released from neurons and extracellular space
function of microglia
monitor health of nearby neurons
engulf debris (dead brain cells) and bacteria (phagocytes)
functions and location of ependymal cells
cilia on the cells help with the circulation of cerebrospinal fluid
secrete CSF
line cavities of the brain and spinal cord
what are the components and functions of cerebrospinal fluid
blood plasma, ions, sugars
protects brain, regulates blood pressure, transport of chemicals
structure and functions of oligodendrocytes
wrapped around neurons’ axons
produce myelin sheaths
what are the types of neuroglia in PNS
satellite cells
schwann cells
what is the function of satellite cells
surround the neuron cell body and provide cushioning
what is the function of schwann cells
produce myelin sheaths around axon
what are the differences between schwann cells and oligodendrocytes
oligodendrocytes wrap around multiple axons/neurons while schwann wrap only one axons
schwann cells can be repaired/regenerated since they have neurilemma)
characteristics of neurons
functional unit of the nervous system
about 100 billion in the brain
high metabolic rate (need constant supply of glucose and oxygen)
function of a neuron
generating and conducting nerve impulses/action potential
results in the excitation or inhibition of nearby neuron/muscle/gland
what are the components of the neuron
cell body
dendrites
axon
characteristics of the cell body of a neuron
metabolic center
has organelles, neurofibrils for cell shape but no centrioles (neurons are non-mitotic)
characteristics of dendrites (neuron)
fibers conduct impulses toward the cell body
a neuron can have hundreds of dendrites
neuron axon characteristics
fibers conduct impulses away from the cell body
only one per neuron
what are the components of the axon and what are they
axon hillock: beginning of axon
axon terminals: contain neurotransmitters
synaptic cleft: gap between terminals and next neuron
synapse: junction where impulse is transmitted (between terminal and cell body/dendrites of next neuron)
characteristics of myelin sheath
white fatty material that covers most of the axons in the PNS and some in the CNS (called myelinated axons)
unmyelinated axons are usually smaller
how are myelin sheath formed by schwann cells
it rolls around the axons at the same place multiple times to form layers
the cytoplasm and nucleus are forced into the outer region away from the axon (called neurilemma)
how does the impulse move across the axon
in saltatory conduction (jump from one node of ranvier to the other not in a straight line)
what is a node of ranvier
space between schwann cells
function of the myelin sheath
protects axon
increases rate of conduction due to electrical insulation
ions cant enter/exit axon where there is myelin
what is multiple sclerosis and characteristics
autoimmune disease where the myelin sheath in the brain and spinal cord is progressively destroyed
the scars (scleroses) slow the transmission of impulses, eventually stops completely
can result in paralysis and loss of sensation
treatment: drugs that affect the activity of the immune system
mainly affects young adults
what are the structural classifications of neurons and their characteristics
based on how many processes extend from the cell body
multipolar: all motoneurons and interneurons
bipolar: special sense organs (ears, eyes, nose) rare in adults
unipolar: majority of sensory neurons
characteristics of sensory, inter and motor neurons
sensory: sensory receptors to CNS, its receptors, dendrites and cell body are in the PNS
inter: connects sensory and motor neurons, cell body is in the CNS
motor: CNS to viscera, muscles and glands, its dendrites and cell body are in the CNS
what are the characteristics of sensory receptors and its subcategories
specialized receptors made by the dendritic ends of sensory neurons
there are cutaneous receptors and proprioreceptors
where are cutaneous receptors and what do they sense
in the skin
sense pain, temperature, touch and pressure
where are proprioreceptors and what do they sense
located in muscles and tendons
sense stretch/tension
what is a cluster of cell bodies called in the CNS vs the PNS
CNS: nuclei
PNS: ganglia
what are bundles of fibers running together called in the CNS vs PNS
CNS: tract
PNS: nerve
what is a large area of nuclei/unmyelinated axons called
gray matter
what is a large area of tracts called
white matter
what are the components of a nerve (small to big)
endoneurium
perineurium
epineurium
what is endoneurium
a connective tissue sheath that surrounds each myelinated axon
what is perineurium
wraps groups of fibers into fascicles
what is epineurium
wraps and binds groups of fascicles
what are the types of nerves and an example of each
sensory: optic
motor: trochlear (rotates eyeball)
mixed: phrenic (senses stimuli from pleura and activates diaphragm)
what are mixed nerves
nerves that contain both sensory and motor fibers
spinal cord has mixed nerves
