Chapter 7 mega review 2 Flashcards
The cellular unit of the nervous system is the neuron. What is the major function of this type of cell
Neurons are highly specialized to transmit messages (nerve impulses) from one part of the body to another
Central nervous system
the brain and spinal cord collectively
Synapse
junction or point of close contact between neurons
Ganglion
a bundle of nerve processes outside the central nervous system
Association neuron (interneuron)
neuron connecting sensory and motor neurons
PNS
spinal and cranial nerves and ganglia
Nuclei
collections of nerve cell bodies inside the CNS
Efferent neurons
neuron that conducts impulses away from the CNS to muscles and glands
Afferent neuron
neuron that conducts impulses toward the CNS from the body periphery
Neurotransmitter
chemicals released by axon terminals
Which part of the neuron is the axon?
An axon is a long, tail-like structure which joins the cell body at a specialized junction called the axon hillock. Many axons are insulated with a fatty substance called myelin. Myelin helps axons to conduct an electrical signal. Neurons generally have one main axon.
Where is the nucleus of an axon located?
The nucleus is in the cell body (soma)
What are the gaps between Schwann cells called?
Nodes of ranvier
What is the function of the axon terminal?
Axons branch profusely at their terminal end, forming hundreds to thousands of axon terminals; contain hundreds of vesicles that contain neurotransmitters
What is the function of the dendrite?
Dendrites are neuron processes that convey impulses toward the cell body
What is the function of the schwann cell?
Schwann cells envelop part of an axon, deposits myelin around small segments of the nerve fiber
What is the metabolic center of the neuron?
Cell body
What is a reflex?
A reflex is a rapid, predictable, and involuntary response to stimuli
Name the 5 essential components to the reflex arc.
Sensory receptor
Effector organ
Sensory neuron
Motor neuron
Synapse between the sensory and motor neurons : CNS integration center
In general, what is the importance of reflex testing in a routine physical examination?
To determine the general health of the motor portion of the nervous system
What is irritability?
The ability to respond to a stimulus
What is conductivity?
The ability to transmit an electrical impulse
What is an action potential?
A long- distance signal (also called nerve impulse) that occurs if the stimulus is strong enough and the Na+ influx is great enough, the local depolarization (graded potential) activated the neuron to initiate an action potential
What are the steps involved in the propagation of an action potential?
Resting membrane is polarized - in the resting state, the external face of the membrane is slightly positive, tis internal face is slightly negative (fewer K+ internally than Na+ externally). The membrane is relatively impermeable to both ions
Stimulus initiates local depolarization - a stimulus changes the permeability of a local “patch” of the membrane, and Na+ diffuses rapidly into the cell. This changes the polarity of the membrane (the inside becomes more + and the outside becomes more negative) at that site
Depolarization and generation of an action potential - if the stimulus is strong enough, depolarization causes membrane polarive to be completely reverses, and an action potential is initiated
Propagation of the action potential - depolarization of the first membrane patch causes permeability changes in the adjacent membrane, and the events described in step 2 are repeated. Thus, the action potential propagates rapidly along the entire length of the membrane
Repolarization - K+ diffuse out of the cell as the membrane permeability changes again, restoring the negative charge on the inside of the membrane and the positive charge on the outside surface. Repolarization occurs in the same direction as depolarization
Explain the difference between a synaptic cleft and a synapse. How is a stimulus transmitted across a synapse?
The synapse consists of three elements:
1) the presynaptic membrane which is formed by the terminal button of an axon,
2) the postsynaptic membrane which is composed of a segment of dendrite or cell body, and
3) The synaptic cleft itself.
Once an action potential reaches the axon terminal, chemicals fuse with the axonal membrane, releasing the neurotransmitter. The neurotransmitter diffuses across the synapse and binds to the receptors on the membrane of the next neuron
What is myelin and where is it found?
Many axons are insulated with a fatty substance called myelin. Myelin helps axons to conduct an electrical signal. (released by Schwann cells in PNS and oligodendrocytes in CNS)
What is the difference between a tract and a nerve?
Tracts are bundles of nerve fibers (neuron processes) in the CNS
Nerves are bundles of nerve fibers (neuron processes) in the PNS
What is the difference between nuclei and ganglia?
Nuclei: cell bodies are found in the CNS in clusters called nuclei
Ganglia: small collections of cell bodies are found in a few sites outside the CNS in the PNS
What is the difference between white matter and gray matter?
White matter consists of dense collections of myelinated fibers (tracts)
Gray matter contains mostly unmyelinated fibers and cell bodies
What is a dendrite?
Dendrites are neuron processes that convey impulses toward the cell body
What are neuroglia (supporting cells)?
– Astrocytes: star shaped cells between neurons and blood vessels. Astrocytes provide structural support and transport substances between blood vessels and neurons.
– Oligodendrocytes: Form myelin sheaths in the brain and spinal cord, produce nerve growth factors
microglial cells: Provide structural support and phagocytosis (immune protection)
- Ependymal Cells : Form a porous layer through which substances diffuse between the interstitial fluid of the brain and spinal cord and the cerebrospinal fluid.
2 types of neuroglia in the PNS
Satellite cells: support ganglia, mop up excess ions and neurotransmitters.
Schwann Cells : Form myelin sheaths, mop up excess ions an neurotransmitters, support neuron regeneration in PNS.
What are bipolar neurons and where are they found?
Bipolar neurons are neurons with 2 processes (an axon and a dendrite)
Are rare in adults, found only in some special sense organs (eye, nose)
What are multipolar neurons and where are they found?
Multipolar neurons are the most common – include all motor and association (interneurons)- found throughout the CNS and PNS
What are unipolar neurons and where are they found?
Have a single process emerging from the cell body
Sensory neurons in PNS ganglia
What are association neurons (or interneurons) and where are they found?
Connect motor and sensory neurons in neural pathways; cell bodies are always in the CNS
What is the difference between a myelinated and an unmyelinated neuron?
Myelinated fibers increase the rate of transmission
What is myelin and where is it found?
Many axons are insulated with a fatty substance called myelin. Myelin helps axons to conduct an electrical signal. (released by Schwann cells in PNS and oligodendrocytes in CNS)
What are the three major regions of the cerebrum?
Frontal Lobe: higher level processes for concentrating, planning, complex problem solving, and judging the consequences of behavior.
Parietal Lobe: Sensory areas provide sensations of temperature, touch, pressure, and pain involving the skin. Association areas function in understanding speech and in using words to express thoughts and feelings.
Temporal lobes: Sensory areas are responsible for hearing. Association areas interpret sensory experiences and remember visual scenes, music and other complex sensory patterns.
Occipital lobes: Sensory areas are responsible for vision. Association areas combine visual images with other sensory experiences.
What is the composition of white matter in the brain?
Myelinated axons
Which region of the brain controls such vital activities as breathing and blood pressure?
Brainstem (medulla oblongata)
What is the function of the cerebellum?
The cerebellum provides the precise timing for skeletal muscle activity and controls our balance.
In what major brain region are the thalamus, hypothalamus, and pineal gland found?
Diencephalon
What are the 4 major regions of the brain?
Cerebral hemispheres
Diencephalon
Brain stem
cerebellum
What is the function of the cerebrum?
Speech, memory, logical emotional response, consciousness, interpretation of sensation, voluntary movement
What is a gyrus?
Elevated ridges
What is a sulcus?
Shallow grooves
What is a fissure?
Deeper grooves (less numerous than sulci)
What are the 4 lobes of the cerebrum and their functions?
Frontal Lobe: higher level processes for concentrating, planning, complex problem solving, and judging the consequences of behavior.
Parietal Lobe: Sensory areas provide sensations of temperature, touch, pressure, and pain involving the skin. Association areas function in understanding speech and in using words to express thoughts and feelings.
Temporal lobes: Sensory areas are responsible for hearing. Association areas interpret sensory experiences and remember visual scenes, music and other complex sensory patterns.
Occipital lobes: Sensory areas are responsible for vision. Association areas combine visual images with other sensory experiences.
Which lobe is the primary somatic sensory area located?
Parietal
What is the function of the primary somatic sensory area?
processing afferent somatosensory input and contributes to the integration of sensory and motor signals necessary for skilled movement
What is the function of the primary motor area?
Impulses traveling from the body’s sensory receptors (except for the special senses) are localized and interpreted in this area of the brain, allows you to recognize pain, coldness, or light touch
What is the function of the corpus callosum?
One very large fiber tract that connects the cerebral hemispheres (left and right)
What are the three regions of the diencephalon and their functions?
–Thalamus: encloses the 3rd ventricle; acts as a relay station for sensory impulses passing upward to the sensory cortex
– Hypothalamus: “under” thalamus; important autonomic nervous system center – plays a role in body temperature, water balance, metabolism, center for drives, emotions (limbic system = emotional -visceral brain)
– epithalamus: forms the. Roof of the 3rd ventricle; includes the pineal body (part of the endocrine seep/wake cycle regulator) and choroid plexus (form CSF)
What are the three regions of the brainstem and their functions?
– Midbrain: reflex centers involved with vision and hearing
– Pons: rounded structure that protrudes just below the midbrain; controls breathing
– Medulla oblongata: most inferior part, regulates vital visceral activities: heart rate, blood pressure, breathing, swallowing, vomiting
What are the 3 connective tissue membranes covering and protecting the CNS structures (meninges)
–Dura mater (most superficial): means “tough or hard mother” is a double layered membrane and surrounds brain
– Arachnoid mater (middle layer): weblike, means “spider”
– Pia mater (innermost): “gentle mother” - is delicate and clings tightly to the surface of the brain and spinal cord following every fold
