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72 Cards in this Set
- Front
- Back
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A synapse between a neuron and a muscle is called a
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neuromuscular junction.
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A synapse between a neuron and a gland is called a
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neuroglandular junction.
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There are three types of neurons:
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Sensory (afferent) neurons
Motor (efferent) neurons Interneurons (association neurons) |
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Sensory receptors are categorized as
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interoceptors
exteroreceptors proprioceptors |
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What are interoceptors responsible for?
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a type of sensory receptor
monitor digestive, respiratory, cardiovascular, urinary, and reproductive systems provide internal sense of taste, deep pressure, and pain |
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What are exteroreceptors responsible for?
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a type of sensory receptor
external senses of touch, temperature, and pressure distance senses of sight, smell, and hearing |
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What are proprioceptors responsible for?
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a type of sensory receptor
monitor position and movement of skeletal muscles and joints |
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What is the function of motor neurons?
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carry instructions from the CNS to peripheral effectors of tissues and organs via axons called efferent fibers
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What are the two major efferent systems?
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1. somatic nervous system (SNS) including all somatic motor neurons that innervate skeletal muscles
2. autonomic nervous system (ANS), including visceral motor neurons that innervate all other peripheral effectors (smooth muscle, cardiac muscle, glands, and adipose tissue) |
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Describe interneurons (association neurons).
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located in brain, spinal cord, and some autonomic ganglia between sensory and motor neurons
responsible for distribution of sensory information and coordination of motor activity involved in higher functions such as memory, planning, and learning |
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What are the domains of the peripheral nervous system (PNS) and the central nervous sytem (CNS)?
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PNS - outside of CNS
CNS - brain and spinal cord The main function of the PNS is to connect CNS to limbs and organs. |
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What are neuroglia and what four types of neuroglia are contained by the CNS?
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Neuroglia are cells that outnumber neurons and provide support and nutrition.
1. ependymal cells (think cerebrospinal fluid) 2. astrocytes (blood-brain barrier) 3. oligodendrocytes (myelin sheaths around axons) 4. microglia |
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What is the function of microglia?
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Microglia are small glia that migrate through neural tissue, cleaning up cellular debris, waste products, and pathogens.
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What are ganglia?
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Clusters of cell bodies of neurons in the PNS, which are surrounded and protected by neuroglia.
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List and describe the neuroglia of the PNS.
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1. satellite cells (amphicytes) - surround ganglia and regulate environment around the neuron
2. Schwann cells (neurilemmacytes) - form myelin sheath [neurilemma] around peripheral axons |
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What is the equilibrium potential?
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the cell potential at which there is no net movement of a particular ion across the cell membrane.
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Gated channels control the ion permeability to
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Na+, K+, Cl-, Ca2+
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What are the two types of electrical signals created by movement across a cell membrane?
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Graded potentials - variable strength, loose strength as they travel through cell
Action potentials - large uniform depolarizations, travel long distances without losing strength |
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Opening a sodium channel produces a
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graded potential. Any stimulus that opens a gated channel produces a graded potential.
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Describe the mechanism of opening a sodium channel.
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1. resting membrane is exposed to a chemical that opens sodium channel. Sodium ions enter, raising transmembrane potential.
2. the movement of sodium ions through the channel produces a local current that depolarizes nearby parts of the cell membrane (graded potential). The change in transmembrane potential is proportional to the stimulus. |
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What is repolarization?
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When the stimulus is removed and the transmembrane potential returns to normal.
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What effect does opening a potassium channel have?
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The opposite effect, as positive ions now move out of (instead of into) the cell. The negativity of the resting potential is increased (hyperpolarization).
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When will an action potential occur?
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If the graded potential is strong enough to reach the axon hillock region and still has a minimum level equal to or greater than the threshold voltage.
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Define "absolute refractory period."
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the period of time that another action potential cannot fire no matter how strong the stimulus
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Define "relative refractory period."
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the period of time that a larger than normal stimulus would be required to initiate another action potential
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What is an action potential?
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propagated changes in transmembrane potential that affect an entire excitable membrane.
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Does any depolarization occur at all if the threshold level is not reached?
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An action potential will not occur, but a local, graded depolarization will be produced.
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When Na+ channels open,
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Na+ enters the cell and the membrane potential increases, becoming positive.
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K+ channels open after Na+ begins to enter cell. Then,
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K+ leaves the cell and Na+ channels close. Then K+ likewise leaves the cell.
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As K+ leaves the cell towards the end, hyperpolarization occurs, preventing an action potential from being generated immediately after. K+ channels then close and
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Excess K+ outside the cell diffuses away, restoring the membrane potential to its original value.
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List the steps involved in the generation of action potentials.
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1. a graded depolarization brings an area of excitable membrane to threshold (from resting potential of -70mV to threshold potential of -60mV).
2. Activation of sodium channels and rapid depolarization: voltage-regulated Na+ channels open. Na+ ions, driven by chemical gradient, flood into cell. Transmembrane potential goes from -60mV (threshold level) to about +30mV. 3. Inactivation of Sodium channels and activation of potassium channels: voltage-regulated sodium channels close at +30mV. Voltage-reg potassium channels are now open, K+ ions diffuse out of cell. Repolarization begins. 4. Return to normal permeability: membrane is capable of generating another action potential if a larger-than-normal stimulus is provided. Voltage-regulated K+ channels close at -70mV. They do not close at same time; K+ loss continues to temporary hyperpolarization to -90mV. At end of relative refractory period, all voltage-reg. channels have closed; membrane is back to resting state. |
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How does saltatory propagation differ from continuous propagation?
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Saltatory propagation occurs only in myelinated axons. It occurs more quickly and takes less energy than continuous propagation. Depolarization only occurs at unmylinated sectiosn called "nodes."
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The diameter of an axon affects the speed of an action potential. The larger the diameter,
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the lower the resistance.
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Describe Type A fibers of axons.
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myelinated
large diameter high speed (140m/sec) carry most time-sensitive info to and from CNS (senses of position, balance, touch, motor impulses to skeletal muscles) |
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Describe Type B fibers of axons.
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myelinated
medium diameter medium speed (18m/sec) sensory info, peripheral effectors, involuntary muscle/gland controls |
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Describe Type C fibers of axons.
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unmyelinated
small diameter slow speed (1m/sec) sensory info, peripheral effectors, involuntary muscle/gland controls |
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Describe the steps of synaptic activity.
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1. an arriving action potential depolarizes the synaptic knob.
2. Ca2+ ions enter cytoplasm of synaptic knob. ACh is released through exocytosis of neurotransmitter vesicles. 3. ACh diffuses across synaptic cleft and binds to receptors on postsynaptic membrane. Chemically regulated Na+ channels on posynaptic surface are activated, producing a graded depolarization. ACh release ceases because calcium ions are removed from cytoplasm of synaptic knob. 4. Depolarization ends as ACh is broken down into acetate and choline by AChE. Synaptic knob reabsorbs choline from the synaptic cleft and uses it to resynthesize ACh. |
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Compounds that have a direct effect on membrane potential:
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ionotropic effects
they open or close gated ion channels |
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Compounds that have an indirect effect on membrane potential
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work through second messengers
link between neurotransmitter (first messenger) and the second messenger may be a G protein which binds GTP binding may activate the enzyme adenylate cyclase, which produces the second messenger cyclic AMP |
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Lipid soluble gases that affect the inside of the cell:
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nitric oxide and carbon monoxide
bind to enzymes in brain cells |
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Temporal summation is
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when two or more action potentials arrive in rapid succession along a single pre-synaptic neuron.
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Spatial summation is
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a way of achieving action potential in a neuron that involves input from multiple cells.
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Neuronal pools are
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functional groups of interconnected neurons in which interneurons are organized. Each has a limited number of input sources and output destinations. A pool may stimulate or depress activity in other parts of CNS.
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The five patterns of neuronal interactions (neural circuits) within neuronal pools are
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1. Divergence - spreading stimulation to many neurons/neuronal pools in the CNS
2. Convergence - bringing input from many sources to a single neuron 3. Serial processing - moving info in a single line 4. Parallel processing - moving same info along several paths simultaneously 5. Reverberation - positive feedback mechanism which continues to function until actively inhibited |
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Describe the cerebrum.
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largest part of the brain
controls thought, memory, conscious movement divided into left and right cerebral hemispheres covered by surface of gray matter |
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Describe the cerebellum.
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coordinates repetitive body movements
second largest part of the brain two hemispheres covered in cerebellar cortex |
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Describe the diencephalon.
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underneath cerebrum and cerebellum
links cerebrum with brain stem divided into left and right thalamus, which relay and process sensory information hypothalamus - involved in hormone production, emotion, autonomic function, and the epithalamus |
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The mesencephalon (midbrain)
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processes sight and sound and maintains consciousness.
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The pons (component of midbrain)
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connects the cerebellum to the brain stem, and is involved in somatic and visceral motor control.
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The medulla oblongata (component of midbrain)
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connects the brain to the spinal cord. It relays information and autonomic functions (heart rate, blood pressure, digestion).
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The limbic system is
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a functional grouping that establishes emotional states, links conscious functions of the cerebral cortex with unconscious, autonomic functions of the brain stem, and facilitates memory storage and revival.
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The limbic system consists of
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the AMYGDALOID BODY interfaces between the limbic system, cerebrum, and sensory systems
the LIMBIC LOBE of the cerebral hemisphere, including the CINGULATE GYRUS, DENTATE GYRUS, PARAHIPPOCAMPAL GYRUS, and the HIPPOCAMPUS (long-term memory) the FORNIX, a tract of white matter that connects the hippocampus with the hypothalamus |
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One of the functions of the reticular formation, awakening from sleep.
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Arousal.
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State of consciousness is determined by
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complex interactions between the reticular formation and the cerebral cortex.
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The reticular activating system (RAS) is
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a diffuse network in the reticular formation that extends from the medulla obongata to the mesencephalon.
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What is an electroencephalogram (EEG)?
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A pattern of the electrical activity (brain waves) assessed when electrodes are placed on the skull.
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Typical brain waves are divided into four categories:
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1. alpha waves, found in healthy, awake adults at rest with eyes closed
2. beta waves, higher frequency, found when person is concentrating or mentally stressed 3. theta waves, found in children or intensely frustrated adults, may indicate brain disorder in adults 4. delta waves, found during sleep, or in adults with brain damage |
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A pacemaker mechanism functions to
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synchronize electrical activity between two brain hemispheres. Brain damage can cause them to become unsynchronized.
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What is a seizure?
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A temporary cerebral disorder that causes the electroencephalogram to change significantly.
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Describe the two types of sleep.
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1. Deep sleep, non-REM sleep, decrease heart rate and blood pressure and respiratory rate, entire body relaxes
2. Rapid eye movement (REM), dreaming, corresponding changes in BP and HR, less receptive to outside stimuli than in deep sleep periods of deep sleep and REM sleep alternate, starting with 1.5 hours of deep sleep and 5 to 20 min. of REM sleep |
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List several characteristics of deep sleep.
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also called "slow wave" or "non-REM (NREM)" sleep
entire body relaxes activity at cerebral cortex is at a minimum heart rate, blood pressure, respiratory rate, and energy utilization decline by up to 30% |
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List several characteristics of rapid eye movement (REM) sleep.
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active dreaming occurs, accompanied by changes in BP and HR
EEG resembles that of the awake state, but in REM sleep, one is less receptive to outside stimuli than in deep sleep muscle tone decreases markedly intense inhibition of somatic motor neurons prevents one from physically producing responses envisioned while dreaming neurons controlling the eye muscles escape this inhibition; eyes move rapidly as dream events unfold |
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_____ are specific bits of information.
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Fact memories
ex. color of a stop sign, scent of a perfume |
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_____ are learned motor behaviors.
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Skill memories
they become incorporated at the unconscious level with repetition complex skill memories involve the integration of motor patterns in the basal nuclei, cerebral cortex, and cerebellum |
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List several characteristics of short-term memories.
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also called "primary memories"
do not last long, but can be recalled quickly while they persist contain small bits of information, such as name or telephone number repeating info in short-term memory will reinforce it and help ensure conversion to a long-term memory |
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The conversion from short-term to long-term memory is called ______.
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memory consolidation.
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Describe secondary and tertiary memories.
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secondary - long-term that fade with time and may require considerable effort to recall
tertiary - long-term that are with you for a lifetime (ex. your name) |
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The _____ and the ____, two components of the limbic system, are essential to memory consolidation.
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amygdaloid body
hippocampus |
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Damage to the ____ leads to an inability to convert short-term memories to new long-term memories, although existing long-term memories remain intact and accessible.
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hippocampus
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Most long-term memories are stored in the _____.
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cerebral cortex.
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What is a memory engram?
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A single circuit that corresponds to a single memory that forms as the result of experience and repetition.
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Describe the two types of amnesia.
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retrograde - lose memory of past events
anterograde - unable to store additional memories, but earlier ones are intact |
