Flashcards in Nervous System Deck (49):
What are neuroglia cells?
-AKA glial cells
-Supply oxygen and nutrients to neurons
-Protect and support neurons
What are the components of a neuron?
-Dendrite, cell body, axon
...are cytoplasmic extensions that receive information and transmit to cell body.
...transmit action potentials away from the cell body.
-Mostly sheathed by myelin
-End in synaptic terminal
What is the purpose of mylein sheath?
-Prevent leakage of signal from axon
-Faster conduction of signal
Nodes of Ranvier...
...gaps between myelin sheath.
-Signal propagates by saltutory conduction
-Type of glial cells
-Produce myelin in CNS
What type of cell produces myelin in the PNS?
Where are neurotransmitters released?
-From axon terminals into synapse to an adjacent dendrite
What are astrocytes?
-Maintain integrity of blood-brain barrier
-Regulate nutrient and dissolved gas conc
What are microglia?
-Remove cell debris and pathogens
What are ependymal cells?
-Line brain ventricles
-Make/maintain cerebral fluid
What are satellite cells?
-Surround neuron cell bodies in ganglia (autonomic nervous system)
What is the resting potential of a neuron?
-Maintained by Na+/K+ pump
-Membrane more permeable to K+, diffuse back out
Describe the transmission of action potentials.
-Causes depolarization (more positive inside cell)
-Reach threshold potential
-Na+ to flow down gradient --> depolarize more of axon
-Reach synaptic terminal --> Ca++ flow in
-Exocytosis of synaptic vesicles with neurotransmitters
-High voltage causes K+ channels to open
-K+ rush down gradient and out of cell
-Voltage gated Na+ channel closes
-Na+/K+ begins again
-Repolarized past resting potential due to K+ still being permeable
-Allows time for regeneration of neurotransmitters
-Potential only moves forward
What is the stimulus intensity coded by?
-Frequency NOT magnitude of action potential
What are factors that allow faster propagation of stimuls?
-More myelinated (only permeable to ions in Nodes of Ranvier)
-Larger diameter of axon
What are the ways neurotransmitters are removed from the synapse?
-Taken back up into the nerve terminal (reused/degraded)
-Degraded by enzymes in synapse
-Diffuse out of synapse
What are afferent neurons?
-Carry sensory information from external/internal environment to brain/spinal cord
What are efferent neurons?
-Carry motor commands from brain/spinal cord to body
What are interneurons?
-Participate only in local circuits
-Linking sensory and motor neurons
Organization of nerves
-Bundle of axons covered with connective tissue (nerves)
-Nerve fibers = plexus
-Neuronal cell body clusters = ganglia(PNS) or nuclei (CNS)
What is the difference between gray and white matter?
-Gray matter is outer portion of cell bodies
-White matter is inner portion of myelinated axons
-Telencephalon and diencephalon
-Cerebral cortex process/integrate sensory/motor
-Thalamus integrate spinal cord and cerebral cortex
-Hypothalamus controls visceral functions (hunger/thirst/sex/temp)
-Relay center for visual and auditory impulses
-Cerebellum, the pons, medulla
-Balance, hand-eye coordination, modulate motor impulses by cerebral cortex
-Relay center to allow cortex to communicate with cerebellum
-Vital functions (breathing, HR, GI)
What makes up the brainstem?
-Midbrain, pons, medulla
-Outer white matter, inner gray
-Can integrate motor responses itself
How does sensory information enter spinal cord?
-Through the dorsal horn (dorsal root ganglia) and exits ventral horn
What does the PNS consist of?
-Somatic and Autonomic
Somatic Nervous System
-Innervate skeletal muscles
-Voluntary movement and reflex arcs
Autonomic Nervous System
-Involuntary - cardiac and smooth muscles
-Sympathetic and parasympathetic
Where is smooth muscles located?
-Blood vessels, digestive tract, bladder, bronchi
Sympathetic Nervous System
-"Fight or Flight"
-Increase bp, HR, blood flow to skeletal muscle
-Decrease gut motility
-Dilate bronchioles to increase gas exchange
What is the primary neurotransmitter for sympathetic nervous system? Parasympathetic?
Parasympathetic Nervous System
-"Rest and digest"
-Lowers hr, increase digestion
-Vagus nerve - innervate thoracic and abdominal viscera
What bends and focuses light?
What controls the diameter of the pupil?
-Iris by responding to intensity of light
...focuses image onto retina.
Describe the synaptic pathway of photoreceptors.
Synapse onto bipolar cells --> ganglion cells --> optic nerve --> brain
What causes action potentials to transmit to brain in hearing?
-Ossicles vibrate and exert pressure on inner ear fluid which stimulates hair cells in basilar membrane
-Pressure --> action potential