Nervous System 1 and 2 Flashcards
Define and describe resting potential
Resting neuron not being stimulated; -70 mv
During RMP, where are the K+ ions located and where are the Na+ ions located?
More K+ inside the cell, more Na+ outside cell
Define and describe action potential
rapid change in membrane potential; first in positive direction, then negative, then returning to RMP
Define threshold
Degree of depolarization reaches -55mv, action potential occurs
Define depolarization
membrane potential less negative (more positive) and closer to 0 mv
Define repolorization
After depolarization, K+ ions diffuse out of cell
Define hyperpolarization
membrane potential more negative; below -70 mv
What are the chemicals responsible for pain sensation
Enkephalins, beta endorphin, and substance P
What is the function of substance P
Functions as neurotransmitter in neurons that conduct impulses associated with pain into spinal cord and brain
What is the function of Enkephalins
Relieve pain sensations by binding to receptors in brain
What is the function of beta endorphin
Acts longer than enkephalins, more potent pain reliever in brain and spinal cord
What are the components of a myelin sheath
Lipids and proteins
What is the structure and function of a unipolar neuron
Single process extends from cell body, divides into two branches that function as one, dendrites near peripheral body (top), other branch enters near spinal cord, most cell bodies found in ganglia
What is the structure and function of a bipolar neuron
Two processes, one arising from either end; one axon, one dendrite, found in specialized parts of eyes, ears, and nose
What is the structure and function of a multipolar neuron
Many processes arises from cell body, one is a axon, rest are dendrites, mostly in brain and spinal cord
Where are voltage gated channels located on a neuron
Axon hillock/initial segment/trigger zone at first part of axon
Where do action potentials begin and end
Begins at axon hillock and ends at axon terminal
Define motor (efferent) neuron and provide location
Located in PNS, carries impulses away from CNS
Define sensory (afferent) neurons and provide location
Located in PNS, carries impulses toward CNS
Define interneurons and provide location
Located in CNS, integrates sensory signals
Describe function and location of synaptic cleft
Space after axon terminal between next target cell; neurotransmitters released to target cell
Where are graded potentials formed and located on a neuron
localized temporary change in membrane potential that occurs at the dendrites in response to a stimulus; decay over distance and time. requires summation to reach threshold
What are the 4 neuroglia cell of the CNS
Astrocytes, Oligodendrocytes, Microglia, and Ependymal cells
What are some of the functions of an Astrocyte
Connects neurons to blood vessels, exchange nutrients and growth factors, for m scar tissue, aid in metabolism of certain substances, part of brain barrier
What are some functions of Oligodendrocytes
Myelinate CNS axons; also provide structural support
What are some functions of Microglia
Phagocytic cell; provides structural support
What are some functions of ependymal cells
Line central canal of spinal cord and ventricles of brain; cover choroid plexuses, help regulate CSF, ciliated columnar cells
What are some functions of Schwann cells
Produce myelin of the peripheral neurons
What are the two neuroglia of the PNS
Schwann cells and Satellite cell
What are some functions of Satellite cells
Provide nutritional support, help regulate concentrations of ions around neuron cells bodies with ganglia
Which are the most numerous neuroglia cells
Astrocytes
Define Summation
The addictive effect of several electrical impulses on a neuromuscular junction; junction between a nerve cell and muscle cell
Define Saltation
jumping action potentials across internodes
Define continuous conduction
Propagation along an unmyelinated axon
What is a dermatome
Area of skin innervated by the sensory nerve fibers of a particular spinal nerve
What is a plexus
Complex network formed by anterior rami (branches) of spinal nerves
What is a tract
Bundles of nerves in CNS
What is the function and location of the cervical enlargement
Thickening in spinal cord and neck region that supplies nerves to upper limbs
What is the function and location of the lumbar enlargement
Thickening in lower back that gives off nerves to lower limbs
What is the function of the filum terminale
Anchors spinal cord
What is the function and location of the conus medullaris
Inferior to lumbar enlargement, spinal cord tapered to structure, nervous tissue extend downward within vertebral canal to become spinal nerves
What is the location and function of the Cervical Plexus
Formed by anterior rami of C1-C4 spinal nerves, supply muscles of skin and neck; C3-C5 contribute to phrenic nerve (motor impulses to diaphragm)
What is the location and function of the Brachial Plexus
Formed by anterior branches C5-T1, deep within shoulders; 5 branches
What are the 5 branches of the Brachial Plexus
Musculocutaneous Nerve, Ulnar/median nerves, Radial nerves, Axillary nerves
What is the function of the Musculocutaneous Nerve
Supply muscles of anterior arms and skin of forearms
What is the function of the Ulnar/Median Nerves
Supply muscles of forearms and hands, skin of hands
What is the function of the Radial Nerve
Supply posterior muscles of arms and skin of forearms and hands
What is the function of the Axillary Nerve
Supply muscles and skin of anterior, lateral, and posterior arms
What is the location and function of the Lumbosacral Plexus
Formed by anterior branches L1-S4, in regions of abdomen and sacral portions in pelvic cavity
What is a monosynaptic reflex
Consists of two neurons; sensory and motor; 1 synapse in spinal cord ex: knee-jerk reflex
What is the withdrawal reflex
Occurs when a person touches or steps on something painful; polysynaptic- sensory, interneuron, and motor neuron
What is a cross extensor reflex
During withdrawal reflex, flexors on affected side contract, extensors inhibited; shifts body weight
How many pairs of spinal nerves are there
31 pair; 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal nerve
Where does the spinal cord begin and end
Begins at brainstem and ends in lower lumbar region, tapering off to form conus medullaris
Define and give location of the meninges
Membranes that protect the brain and spinal cord; 3 layers; Dura mater, Arachnoid mater, pia mater
Where is CSF located within meninges
Within Arachnoid mater, in subarachnoid space
What is the function of the Pia Mater
Inner layer of meninges attached to brain surface, contains blood vessels, and nerves that nourish CNS
What is the function of the Dura Mater
Outer layer of tough dense connective tissue; contains dural sinuses and epidural space
What is the function of the posterior/dorsal root
Dorsal roots allow sensory neurons to enter spinal cord
Define ascending tracts
Spinal tracts that conduct sensory information to brain
Define descending tracts
Spinal tracts that conduct motor commands from brain via motor neurons reaching muscles and glands
Define and give location of Fasciculus Gracilis and Fasciculus Cuneatus (Ascending tract)
Located in posterior funiculi; conduct sensory impulses associated with senses of touch, pressure, and body movement from skin, muscles, tendons, and joints to brain
Define and give location of Spinothalamic tracts (lateral/anterior) (Ascending tract)
Located in the lateral and anterior funiculi; conduct sensory impulses associated with the senses of pain, temperature, touch, pressure, from various regions to brain
Define and give location of Spinocerebellar tracts (posterior/anterior) (Ascending tract)
Located in lateral funiculi; conduction of sensory impulses required for coordination of muscles movements from muscles of lower limbs and trunk to cerebellum
Define and give location of Corticospinal tracts (lateral/anterior) (Descending tract)
Located in lateral and anterior funiculi; conduct motor impulses associated with voluntary movements from the brain to skeletal muscles
Define and give location of Reticulospinal tracts (lateral/anterior/medial) (Descending tract)
Located in lateral and anterior funiculi; conduct motor impulses associated with the maintenance of muscle tone and activity of sweat glands from brain
Define and give location of Rubrospinal tract (Descending tract)
Located in lateral funiculi; conduct motor impulses associated with muscular coordination from the brain
What nerve is associated with Carpal Tunnel syndrome
Median nerve (compressed in carpal tunnel)
What are the five parts of reflex arc
Receptor, Sensory neuron, Interneuron, Motor neuron, and effector
What is a receptor
Receptor end of a dendrite or specialized receptor cell; sensitive to a specific type of internal or external change
What is a sensory neuron
Dendrite, cell body and axon of sensory neuron; conducts an impulse from the receptor into brain or spinal cord
What is a motor neuron
Dendrite, cell body, axon of motor neuron; conducts an impulse from brain or spinal cord out to synapse with an effector
What is an interneuron
Dendrite, cell body, axon of a neuron with brain or spinal cord; serves as a processing center, conducts impulse from sensory to its synapse with motor neuron
What is an effector
Muscle or gland; responds to stimulation by the motor neuron and produces the reflex or behavioral action
What is the structure of a peripheral nerve
Nerves are bundles of axons with 3 coverings; endoneurium (surrounds individual axons), perineurium(encloses each fascicle), and epineurium(surrounds group of bundles fascicles, outermost layer)
