p.1
Resting Membrane Potential
What is the resting membrane potential?
The electrical potential difference across the membrane of a resting neuron.
p.1
Resting Membrane Potential
What ions are primarily involved in establishing the resting membrane potential?
Sodium (Na+) and Potassium (K+).
p.1
Action Potential Mechanism
What is an action potential?
A rapid change in membrane potential that propagates along the neuron.
p.1
Action Potential Mechanism
What is the ionic basis of an action potential?
The influx of sodium ions followed by the efflux of potassium ions.
p.1
Nerve Impulse Conduction
How does nerve impulse conduction occur?
Through the propagation of action potentials along the axon.
What is synaptic transmission?
The process by which a nerve impulse is transmitted across a synapse.
What role do neurotransmitters play in synaptic transmission?
They are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron.
p.1
Integration of Synaptic Inputs
What is integration of information by summation?
The process by which multiple synaptic inputs are combined to determine if an action potential will occur.
p.2
Nervous System Overview
What are the two main divisions of the nervous system?
Central Nervous System and Peripheral Nervous System.
p.2
Nervous System Overview
What does the Central Nervous System consist of?
The brain and spinal cord.
p.2
Nervous System Overview
What is the function of the Peripheral Nervous System?
To connect the Central Nervous System to the rest of the body.
p.2
Nervous System Overview
What are the two main components of the Peripheral Nervous System?
Autonomic nervous system and somatic nervous system.
p.60
Neuron Structure and Function
How does light enter the eye?
Through the cornea and pupil.
p.22
Myelination and Its Importance
What is the structure of the myelin sheath?
It consists of many concentric layers wrapped around the axon, but lacks cytoplasm.
p.22
Myelination and Its Importance
Where does the nucleus of the Schwann cell remain in relation to the myelin sheath?
In between the myelin sheath and the neurilemma.
p.62
Neuron Structure and Function
What is chemoreception?
The process by which organisms detect chemical stimuli in their environment.
p.44
Myelination and Its Importance
How much faster is conduction in myelinated fibers compared to fiber diameter?
Approximately 6 times the fiber diameter.
p.24
Myelination and Its Importance
What is the role of myelin sheath in action potential propagation?
It allows for very fast propagation of action potentials due to saltatory conduction.
p.107
Integration of Synaptic Inputs
Can a single postsynaptic cell receive input from multiple presynaptic cells?
Yes, it may receive synaptic input from a large number of presynaptic cells.
p.76
Action Potential Mechanism
What happens if the threshold potential is reached during an action potential?
More Na+ channels open, triggering an action potential.
p.110
Synaptic Transmission
What effect does an inhibitory synapse have on the postsynaptic cell's firing threshold?
It brings the postsynaptic cell further from the firing threshold.
p.88
Myelination and Its Importance
How does myelin sheathing affect the conduction of action potentials?
It allows neurons to conduct action potentials much faster than non-myelinated neurons.
p.95
Synaptic Transmission
Where are synaptic vesicles located?
Within the synaptic terminal.
p.47
Types of Neurons and Nerve Fibers
What classification system is used based on diameter and conduction of impulse?
Erlanger-Gasser classification.
p.111
Integration of Synaptic Inputs
How does a postsynaptic neuron integrate information?
By summing its synaptic potentials.
p.108
Synaptic Transmission
What are the two types of synapses between neurons?
Excitatory and inhibitory.
p.110
Synaptic Transmission
What is the function of an inhibitory synapse?
It releases a neurotransmitter that hyperpolarizes the postsynaptic cell, causing an inhibitory postsynaptic potential (IPSP).
p.24
Myelination and Its Importance
What is a key characteristic of myelinated nerve fibers?
They have a high insulating capacity, preventing cross stimulation.
p.2
Nervous System Overview
What does the parasympathetic nervous system do?
It promotes 'rest and digest' functions.
p.114
Integration of Synaptic Inputs
What is the role of inhibitory neurons in muscle response?
They help coordinate the response of effectors like muscles.
p.64
Integration of Synaptic Inputs
Why do foods not taste good when we have a cold?
Because we lose the sense of 'flavor'.
p.43
Types of Neurons and Nerve Fibers
How does the diameter of a nerve fiber influence the threshold of excitation?
A greater diameter leads to a lesser threshold of excitation.
p.58
Nervous System Overview
How do ears contribute to hearing?
They gather sound waves from the environment.
p.36
Neuroglia and Support Cells
What important role do fibrous astrocytes play?
In the formation of the blood-brain barrier.
p.16
Neuron Structure and Function
How many axons does each neuron have?
Each neuron has only one axon.
p.50
Nervous System Overview
What does sensory input refer to?
The information received by sensory receptors from the environment.
p.82
Nerve Impulse Conduction
Why is the axon considered a poor conductor of electrical charge?
Because it is leaky to charge in the form of ions.
p.16
Neuron Structure and Function
What is the primary function of an axon?
To carry impulses away from the cell body.
p.111
Integration of Synaptic Inputs
What is spatial summation?
The integration of synaptic potentials from multiple sources in space.
p.113
Integration of Synaptic Inputs
Do spatial and temporal summation occur together?
Yes, both often occur together.
p.109
Synaptic Transmission
What is the function of an excitatory synapse?
It releases a neurotransmitter that depolarizes the postsynaptic cell, causing an excitatory postsynaptic potential (EPSP).
p.61
Neuron Structure and Function
What happens when light breaks pigments in photoreceptor cells?
It releases energy that stimulates neurons connecting to the optic nerve.
p.67
Resting Membrane Potential
What does the microelectrode measure?
The electrical potential inside the axon relative to the outside.
p.28
Nerve Impulse Conduction
What is the function of the conductive zone in neurons?
It transmits propagated impulses to the nerve ending.
p.41
Neuroglia and Support Cells
What are Schwann cells?
Major glial cells in the peripheral nervous system (PNS).
p.17
Neuron Structure and Function
What are the two types of axons based on myelination?
Medullary and non-medullary.
p.79
Action Potential Mechanism
What is the state of K+ channels during the initial phase of the action potential?
K+ channels are still open.
p.73
Resting Membrane Potential
What happens when K+ channels open?
K+ efflux occurs, driving the cell interior more negative (hyperpolarization).
p.51
Nervous System Overview
What does the Peripheral Nervous System (PNS) consist of?
Cranial nerves and spinal nerves.
p.50
Nervous System Overview
What is a sensory receptor?
A specialized cell that detects and responds to sensory stimuli.
p.16
Neuron Structure and Function
Where does the axon arise from?
From the axon hillock of the soma.
p.4
Neuron Structure and Function
What unique structures do neurons contain?
Nissl granules and neurofibrillae.
p.35
Neuroglia and Support Cells
What are the two types of astrocytes?
Fibrous astrocytes and protoplasmic astrocytes.
p.108
Synaptic Transmission
What role do chemically gated ion channels play in synapses?
They determine the response of the postsynaptic cell.
p.107
Integration of Synaptic Inputs
What determines the response of the postsynaptic cell to synaptic inputs?
The type of chemically gated ion channel that has been opened.
p.114
Integration of Synaptic Inputs
How do inhibitory neurons affect opposing muscle contraction?
They prevent the contraction of an opposing muscle.
p.112
Integration of Synaptic Inputs
What is temporal summation in the context of postsynaptic potentials?
It refers to the summation of postsynaptic potentials as long as the events have not faded out.
p.44
Nerve Impulse Conduction
What is the speed of conduction in myelinated fibers?
Varies from 6 to 120 meters per second.
p.76
Action Potential Mechanism
What is the role of Na+ channels in the action potential?
They open to depolarize the membrane potential.
p.110
Synaptic Transmission
What is the result of K+ channels opening in an inhibitory synapse?
It allows the efflux of K+ from the postsynaptic cell.
p.114
Integration of Synaptic Inputs
When do inhibitory neurons become active in relation to excitatory neurons?
They become simultaneously active with excitatory neurons stimulating the quadriceps muscle.
p.47
Types of Neurons and Nerve Fibers
What are the two types of nerve fibers based on function?
Sensory nerve fibers (afferent) and motor nerve fibers (efferent).
p.26
Myelination and Its Importance
What role does neurilemma play in myelinated nerve fibers?
It is necessary for myelinogenesis.
p.87
Action Potential Mechanism
What happens to Na+ channels during the repolarizing and undershoot phases?
The inactivation gates of the Na+ channels are closed, blocking any Na+ influx.
p.46
Types of Neurons and Nerve Fibers
What are the two types of nerve fibers based on origin?
Cranial nerves (arising from the brain) and spinal nerves (arising from the spinal cord).
p.65
Nervous System Overview
What is chemoreception?
The process of detecting chemical stimuli, including the sense of pain.
p.62
Neuron Structure and Function
What do taste buds detect?
Certain ions dissolved in saliva.
p.82
Nerve Impulse Conduction
What happens to the flow of electrical charge over a short distance in an axon?
It is greatly diminished.
p.16
Neuron Structure and Function
Can an axon synthesize its own proteins?
No, it depends upon the soma for protein synthesis.
p.83
Action Potential Mechanism
How is the action potential propagated along the axon?
It is regenerated like a series of relay stations.
p.83
Action Potential Mechanism
What causes the adjacent membrane to depolarize during action potential propagation?
Localized flow of current from the region undergoing an action potential.
p.13
Neuron Structure and Function
What is the location of the nucleus in a neuron?
Centrally placed in the soma.
p.14
Neuron Structure and Function
What is the role of the Golgi apparatus in nerve cells?
It is concerned with processing and packing of proteins into granules.
p.76
Action Potential Mechanism
What initiates the depolarization of the membrane potential in an action potential?
A stimulus opens the activation gate of some Na+ channels.
p.43
Types of Neurons and Nerve Fibers
What is a general feature of nerve fibers regarding diameter?
Greater diameter leads to greater speed of conduction.
p.53
Types of Neurons and Nerve Fibers
What type of neurons are found in the bipolar structure?
Bipolar neurons are found in the eye, ear, and olfactory system.
p.41
Neuroglia and Support Cells
What important role do Schwann cells play?
They play an important role in nerve regeneration.
p.63
Nervous System Overview
What is chemoreception?
The process of detecting chemical stimuli, such as smell.
p.15
Neuron Structure and Function
What are dendrites?
Tapering and branching extensions of the soma.
p.74
Action Potential Mechanism
How does an action potential differ from graded potentials?
An action potential is an all-or-none response, while graded potentials increase with stimulus strength.
p.8
Neuron Structure and Function
What is a characteristic structure of motor neurons?
Generally, they have a long axon and short dendrites.
p.72
Integration of Synaptic Inputs
What is a consequence of altering the concentration of ions in the body?
It can disrupt cellular functions and lead to health issues.
p.42
Neuroglia and Support Cells
How do satellite cells contribute to the PNS?
By helping in the regulation of the chemical environment of the extracellular fluid around PNS neurons.
p.66
Resting Membrane Potential
What type of proteins are involved in creating resting potential?
Transmembrane proteins (ion channels).
p.40
Neuroglia and Support Cells
How do oligodendrocytes support CNS neurons?
By forming semi-still connective tissue between neurons.
p.39
Neuroglia and Support Cells
What role do microglia play in the CNS?
They act as macrophages of the CNS.
p.13
Neuron Structure and Function
What does the prominent nucleoli in the neuron contain?
Ribose nucleic acid (RNA).
p.27
Action Potential Mechanism
What is generated in the origin of conducted impulse zone?
Propagated action potential.
p.92
Synaptic Transmission
What is a characteristic of electrical synapses regarding delay?
They have a very short delay.
p.108
Synaptic Transmission
What determines whether a synapse is excitatory or inhibitory?
The type of neurotransmitter released by the presynaptic cell.
What role do hair cells in the cochlea play in sound transmission?
They vibrate to certain frequencies and send signals down the auditory nerve.
p.2
Nervous System Overview
What is the role of the sympathetic nervous system?
To prepare the body for 'fight or flight' responses.
p.110
Synaptic Transmission
What happens when Cl- channels open in an inhibitory synapse?
It allows the influx of Cl- into the postsynaptic cell.
p.56
Neuron Structure and Function
What do sensory receptors do?
They receive stimuli from the environment and transmit stimuli to neurons.
p.28
Nerve Impulse Conduction
What type of transmission occurs in the conductive zone?
All or none transmission.
p.58
Nervous System Overview
What is mechanoreception?
A sensory process that includes hearing.
p.36
Neuroglia and Support Cells
What do fibrous astrocytes cover?
Nerve cells and synapses.
p.79
Action Potential Mechanism
What effect does the continued efflux of K+ have on the membrane potential?
It keeps the potential below resting level.
p.73
Action Potential Mechanism
What is the effect of open Na+ channels on the cell?
Na+ influx drives the cell interior more positive (depolarization).
p.97
Synaptic Transmission
What happens to neurotransmitters after they are released into the synaptic cleft?
They diffuse across the synaptic cleft and bind with receptors on chemically gated ion channels in the postsynaptic membrane.
p.35
Neuroglia and Support Cells
Where are astrocytes found?
Throughout the brain, joining to blood vessels.
p.50
Nervous System Overview
What is integration in the context of the nervous system?
The process of interpreting sensory input and deciding on a response.
p.20
Myelination and Its Importance
What happens to myelin when the extracellular membrane protein (Po) is compacted?
It locks the extracellular portion of Po against the apposing membrane.
p.33
Neuroglia and Support Cells
Do neuroglia transmit nerve impulses?
No, they are non-excitable and do not transmit nerve impulses.
p.48
Myelination and Its Importance
Which type of nerve fibers are myelinated?
All fibers except Type C fibers.
p.39
Neuroglia and Support Cells
What is the size comparison of microglia to other neuroglial cells?
They are the smallest neuroglial cells.
p.3
Neuron Structure and Function
What is the specialized function of neurons?
Integration and transmission of nerve impulses.
p.14
Neuron Structure and Function
Is the Golgi apparatus in nerve cells the same as in other cells?
Yes, it functions similarly to the Golgi apparatus in other cells.
p.114
Integration of Synaptic Inputs
What happens in the knee-jerk reflex regarding inhibitory neurons?
The flexor muscle is prevented from contracting by an inhibitory neuron.
p.56
Neuron Structure and Function
What are the primary human senses?
Photoreception, chemoreception, mechanoreception, thermoreception.
p.28
Synaptic Transmission
What happens in the secretory zone of a neuron?
Action potentials cause the release of neurotransmitters.
p.78
Action Potential Mechanism
What is the effect of K+ efflux on membrane potential?
It drops the membrane potential back to and below resting potential.
p.98
Synaptic Transmission
What occurs when the neurotransmitter is no longer bound to the ion channels?
The channel closes and the postsynaptic cell begins to return to its resting condition.
p.10
Types of Neurons and Nerve Fibers
Where are Golgi Type II neurons typically found?
In the cerebral cortex and spinal cord.
p.42
Neuroglia and Support Cells
Where are satellite cells located?
On the extensor surface of PNS neurons.
p.5
Types of Neurons and Nerve Fibers
What classification of neurons is based on the length of the axon?
Long axon (projection neurons) and short axon (local circuit neurons).
p.42
Neuroglia and Support Cells
What is one function of satellite cells?
To provide physical support to PNS neurons.
p.35
Neuroglia and Support Cells
What structures do astrocytes invest?
Synaptic structures, neuronal bodies, and neuronal processes.
p.50
Nervous System Overview
What is motor input?
The signals sent from the nervous system to muscles or glands to elicit a response.
p.82
Nerve Impulse Conduction
What is the role of passive electrotonic spread in an axon?
It is an important component of the propagation of action potentials down the axon.
p.54
Neuron Structure and Function
What do motor neurons do?
They carry signals from the central nervous system to effectors.
p.21
Myelination and Its Importance
What is myelinogenesis?
The formation of myelin sheath around the axon.
p.48
Types of Neurons and Nerve Fibers
How are Type A nerve fibers further subdivided?
Into four groups: Aα (Type I), Aβ (Type II), Aγ (Type III), and Aδ.
p.34
Neuroglia and Support Cells
Name two types of central neuroglial cells.
Astrocytes and oligodendrocytes.
p.29
Neuron Structure and Function
In which directions does axonal transport occur?
In both anterograde and retrograde directions.
What are the functions of Endorphins?
Mood enhancement and pain reduction.
p.52
Neuron Structure and Function
What are dendrites?
Branch-like structures that receive signals from other neurons.
p.34
Neuroglia and Support Cells
What are Schwann cells associated with?
Peripheral neuroglial cells.
p.24
Myelination and Its Importance
How does myelination affect mobility in higher animals?
It results in quicker mobility.
p.109
Synaptic Transmission
What type of channels are opened by the neurotransmitter in an excitatory synapse?
Chemically gated Na+ channels.
p.2
Nervous System Overview
What does the autonomic nervous system regulate?
Involuntary bodily functions.
p.43
Types of Neurons and Nerve Fibers
How does the diameter of a nerve fiber affect the magnitude of spike potential?
A greater diameter results in a greater magnitude of spike potential.
p.91
Nerve Impulse Conduction
What is the significance of giant axons in the earthworm?
They facilitate rapid nerve impulse conduction.
p.46
Types of Neurons and Nerve Fibers
What are the two main types of nerve fibers based on structure?
Myelinated nerve fibers and non-myelinated nerve fibers.
p.87
Action Potential Mechanism
Why can't the region just recovering from an action potential be stimulated?
Because it is in the K+ outflow region and cannot be stimulated by local current flow.
p.10
Types of Neurons and Nerve Fibers
What are Golgi Type I neurons characterized by?
They have long axons and their cell body is situated in the CNS, reaching remote peripheral organs.
p.4
Neuron Structure and Function
What is a neuron?
The structural and functional unit of the nervous system.
p.51
Nervous System Overview
What is the role of the Central Nervous System (CNS)?
To process and transmit information throughout the body.
p.17
Action Potential Mechanism
What is the primary function of axons in relation to signals?
To convert electrical signals (action potentials) to chemical signals.
p.3
Neuron Structure and Function
How many neurons are estimated to be in the human CNS?
More than 100 billion neurons.
p.50
Nervous System Overview
What is an effector?
A muscle or gland that carries out the response to motor input.
p.69
Resting Membrane Potential
What is the K+ equilibrium potential?
It exists when the electric charge across the membrane prevents net diffusion of K+ ions down their concentration gradient.
p.33
Neuroglia and Support Cells
Can neuroglia multiply?
Yes, they are capable of multiplying by mitosis.
p.29
Neuron Structure and Function
What is the rate of slow axonal transport?
1 mm/day, transporting substances dissolved in cytoplasm, such as proteins.
p.68
Resting Membrane Potential
What ions are primarily involved in the resting membrane potential?
Sodium (Na⁺) and Potassium (K⁺).
p.23
Myelination and Its Importance
Do non-myelinated nerves have internodes or nodes of Ranvier?
No, they do not have internodes or nodes of Ranvier.
p.29
Neuron Structure and Function
What is transported during retrograde transport?
Neurotrophins and viruses.
p.90
Myelination and Its Importance
What role does myelin sheathing play in nerve impulse conduction?
It improves the speed of nerve impulse conduction through saltatory conduction.
p.107
Integration of Synaptic Inputs
What is the role of the postsynaptic cell in synaptic integration?
It integrates information from presynaptic cells.
p.2
Nervous System Overview
What are the two branches of the autonomic nervous system?
Sympathetic nervous system and parasympathetic nervous system.
p.57
Nervous System Overview
What do free nerve endings in the skin sense?
Changes in temperature (differences rather than absolutes).
p.73
Resting Membrane Potential
What can alter membrane potential?
The opening of specific ion channels.
p.98
Synaptic Transmission
What happens to the neurotransmitter after it binds to the ion channels?
It is either degraded by an enzyme or taken up by the presynaptic neuron.
p.51
Nervous System Overview
What are the main components of the Central Nervous System (CNS)?
The brain and spinal cord.
p.26
Neuroglia and Support Cells
Where is neurilemma absent?
In the central nervous system (CNS).
p.66
Resting Membrane Potential
What is the resting potential in neurons?
An electric charge difference across their plasma membranes.
p.19
Myelination and Its Importance
What is the structure of the myelin sheath?
Concentric layers of protein alternating with lipid.
p.97
Synaptic Transmission
What occurs when neurotransmitters bind to receptors on chemically gated ion channels?
The ion channel opens, allowing ions (such as Na+) to diffuse into the postsynaptic cell.
p.6
Types of Neurons and Nerve Fibers
What is a unipolar neuron?
A neuron having only one pole, from which both axon and dendrites arise, present in the embryonic stage in humans.
p.96
Synaptic Transmission
What is the effect of elevated Ca2+ in the synaptic terminal?
It causes synaptic vesicles to fuse with the presynaptic membrane.
p.15
Neuron Structure and Function
What structures are found in dendrites?
Nissl granules and neurofibrils.
p.14
Neuron Structure and Function
What is the primary function of mitochondria in nerve cells?
To serve as the powerhouse of the nerve cell where ATP is produced.
p.70
Resting Membrane Potential
What is resting potential?
The electrical potential difference across the membrane of a neuron when it is not actively transmitting a signal.
p.34
Neuroglia and Support Cells
What are the two types of astrocytes?
Fibrous astrocytes and protoplasmic astrocytes.
p.18
Myelination and Its Importance
What is the function of the myelin sheath?
Insulates the nerve fiber.
p.111
Integration of Synaptic Inputs
What is temporal summation?
The integration of synaptic potentials over time.
p.113
Integration of Synaptic Inputs
What is spatial summation?
It occurs when more than one synaptic input becomes simultaneously active.
p.109
Synaptic Transmission
What ions flow into the postsynaptic cell during an EPSP?
Positive charge (Na+ ions).
p.77
Action Potential Mechanism
What happens to Na+ channels when the threshold potential is reached?
All Na+ channels' activation gates open.
p.79
Action Potential Mechanism
What happens to the Na+ channels at the beginning of the action potential?
Both gates of the Na+ channel are closed.
p.98
Synaptic Transmission
What causes the bound neurotransmitters to dissociate from the ion channels?
The uptake of neurotransmitter by the presynaptic neuron.
p.5
Types of Neurons and Nerve Fibers
What are the classifications of neurons based on the number of poles?
Unipolar, bipolar, and multipolar.
p.17
Synaptic Transmission
What do synaptic knobs contain?
Granules or vesicles with synaptic transmitters.
p.15
Neuron Structure and Function
What are dendritic spines?
Knobby projections found on the dendrites of the cerebral cortex and cerebellar cortex.
p.8
Types of Neurons and Nerve Fibers
What do sensory or afferent neurons do?
Carry impulses from the periphery to the CNS.
p.97
Action Potential Mechanism
What effect does the influx of Na+ ions have on the postsynaptic cell?
It depolarizes the postsynaptic cell.
p.6
Types of Neurons and Nerve Fibers
What characterizes a bipolar neuron?
A neuron having two poles, with the axon arising from one pole and dendrites from the other pole.
p.96
Synaptic Transmission
What do vesicles do after fusing with the presynaptic membrane?
They dump their contents into the synaptic cleft.
p.72
Integration of Synaptic Inputs
What is a fourth situation that can alter ion concentration in the body?
Certain medications or diuretics.
p.92
Synaptic Transmission
What is the effect of electrical synapses on action potentials?
The action potential in the presynaptic neuron can directly trigger an action potential in the postsynaptic cell.
p.23
Myelination and Its Importance
What characterizes a non-myelinated nerve?
It has no myelin sheath formation.
p.68
Resting Membrane Potential
What is the primary reason for the resting membrane potential?
The passive efflux of K⁺ from the cell.
p.11
Neuron Structure and Function
What are the main components of a neuron?
Nerve cell body, axon, and dendrites.
p.18
Neuron Structure and Function
What organelles are contained within the axis cylinder?
Mitochondria, neurofibrils, and vesicles.
p.23
Myelination and Its Importance
What is the relationship between neurilemma and axis cylinder in non-myelinated nerves?
Neurilemma and axis cylinder are close to each other.
p.11
Neuron Structure and Function
What direction does the axon carry impulses?
Centrifugally (away from the soma).
p.13
Neuron Structure and Function
What type of granules are Nissl granules?
Small basophilic granules or membrane-bound cavities.
p.109
Synaptic Transmission
What effect does an EPSP have on the postsynaptic cell?
It brings the postsynaptic cell closer to its firing threshold.
p.110
Synaptic Transmission
What types of channels open in an inhibitory synapse?
Chemically gated K+ channels or Cl- channels.
p.95
Synaptic Transmission
What do synaptic vesicles contain?
Large numbers of neurotransmitter molecules.
p.43
Types of Neurons and Nerve Fibers
What is the relationship between nerve fiber diameter and the duration of spike?
Greater diameter results in a smaller duration of spike.
p.77
Action Potential Mechanism
What is the state of K+ channels at threshold potential?
K+ channels are mostly closed but begin to slowly open.
p.91
Neuron Structure and Function
What is a stellate ganglion?
A cluster of nerve cell bodies in the nervous system.
p.47
Types of Neurons and Nerve Fibers
What are the two types of nerve fibers based on neurotransmitter secretion?
Adrenergic nerve fibers and cholinergic nerve fibers.
p.57
Nervous System Overview
What type of temperature changes do thermoreceptors detect?
Differences in temperature.
p.87
Action Potential Mechanism
What is unidirectional propagation in the context of action potentials?
The action potential moves in one direction, from the axon hillock to the axon terminals.
p.26
Myelination and Its Importance
What is the function of neurilemma in non-myelinated nerve fibers?
It serves as a covering membrane.
p.41
Neuroglia and Support Cells
How do Schwann cells assist during nerve regeneration?
By removing cellular debris through their phagocytic activity.
p.17
Neuron Structure and Function
What are the terminal branches of an axon called?
Terminal buttons or telodendria.
p.47
Types of Neurons and Nerve Fibers
What are the three major groups of nerve fibers classified by Erlanger-Gasser?
Type A, Type B, and Type C nerve fibers.
p.46
Types of Neurons and Nerve Fibers
What type of nerve fibers supply internal organs?
Visceral or autonomic nerve fibers.
p.17
Neuron Structure and Function
What do axons divide into at their ends?
Terminal branches ending in synaptic knobs.
p.74
Action Potential Mechanism
What triggers an action potential?
A depolarizing potential that reaches the threshold potential.
p.63
Nervous System Overview
What is the primary function of the olfactory patch?
To detect and distinguish between different chemicals in the air.
p.8
Types of Neurons and Nerve Fibers
What are motor or efferent neurons responsible for?
Carrying impulses from the CNS to peripheral effector organs like muscles, glands, and blood vessels.
p.79
Action Potential Mechanism
What occurs when K+ channels finally close?
Na+ channel inactivation gates open to return to resting state.
p.36
Neuroglia and Support Cells
How do fibrous astrocytes contribute to the blood-brain barrier?
By sending processes to blood vessels of the brain.
p.87
Action Potential Mechanism
What is the refractory period?
The time during which a neuron cannot be stimulated to fire another action potential.
p.63
Nervous System Overview
How many different chemicals can human olfactory receptors distinguish?
About 1000 different chemicals.
p.82
Nerve Impulse Conduction
How does the conduction of action potentials differ from conduction along a wire?
It is not like conduction of charge along a wire conductor.
p.4
Neuron Structure and Function
What are the main components found in the cytoplasm of a neuron?
Nucleus and most organelles.
p.51
Nervous System Overview
What is the function of the Peripheral Nervous System (PNS)?
To connect the CNS to the limbs and organs.
p.65
Nervous System Overview
How is pain related to chemoreception?
The sense of pain is a form of chemoreception.
p.5
Types of Neurons and Nerve Fibers
How can neurons be classified based on their function?
Sensory neurons, motor neurons, and interneurons.
p.96
Synaptic Transmission
What triggers the opening of voltage-gated Ca2+ channels at the synaptic terminal?
Arrival of an action potential.
p.15
Neuron Structure and Function
What is the function of dendrites?
Conduct impulses towards the cell body and generate local potentials.
p.66
Resting Membrane Potential
What is the function of the Na+/K+ pump?
It helps maintain ion concentration differences across the membrane.
p.74
Action Potential Mechanism
Is the size of an action potential dependent on the stimulus strength?
No, it is independent of the stimulus.
p.29
Neuron Structure and Function
What is the primary function of axonal transport?
To transport substances from the soma to the synaptic ending.
p.92
Synaptic Transmission
How do electrical synapses function?
They allow ionic currents to pass directly from one cell to another through gap junctions.
p.34
Neuroglia and Support Cells
What are the two main classifications of neuroglial cells?
Central neuroglial cells and peripheral neuroglial cells.
p.45
Nerve Impulse Conduction
What is the relationship between the speed of conduction and the diameter of nonmyelinated fibers?
The speed of conduction is proportional to the square root of the diameter.
p.68
Resting Membrane Potential
What happens to the charge inside the cell as K⁺ leaves?
A net negative charge is left behind due to large anions (A⁻) that cannot cross the membrane.
p.23
Myelination and Its Importance
Is there a neurilemma in the CNS for non-myelinated nerves?
No, there is no neurilemma in the CNS.
p.90
Myelination and Its Importance
Why do some invertebrates need to rapidly conduct nerve impulses?
For escape responses to distant muscles.
p.66
Resting Membrane Potential
What creates the resting potential in neurons?
Ion concentration differences created by ion pumps and ion channels.
p.19
Myelination and Its Importance
What is a myelinated nerve fiber?
A nerve fiber insulated by myelin sheath.
p.62
Neuron Structure and Function
What are the basic tastes identified by taste buds?
Salty, sweet, sour, and bitter.
p.33
Neuroglia and Support Cells
What are neuroglia?
Supporting cells of the nervous system.
p.14
Neuron Structure and Function
What are neurofibrillae?
Thread-like structures present all over the cell, consisting of microtubules and microfilaments.
p.6
Types of Neurons and Nerve Fibers
What defines a multipolar neuron?
A neuron with multiple poles, where the axon arises from one pole and all other poles give rise to dendrites.
p.94
Synaptic Transmission
What is required for communication at a chemical synapse?
A chemical messenger must diffuse across a narrow gap between cells.
p.39
Neuroglia and Support Cells
What is one of the main functions of microglia?
To engulf and destroy microorganisms and cellular debris.
p.70
Resting Membrane Potential
What ions are primarily involved in establishing resting potential?
Sodium (Na+) and potassium (K+) ions.
p.21
Myelination and Its Importance
When is myelination of the pyramidal tract completed?
Around the end of the 2nd year of life.
p.70
Resting Membrane Potential
How does the sodium-potassium pump affect resting potential?
It actively transports 3 sodium ions out and 2 potassium ions into the cell, maintaining the negative resting potential.
p.23
Myelination and Its Importance
What cells are responsible for myelinogenesis in the CNS?
Oligodendrocytes, not Schwann cells.
p.25
Neuron Structure and Function
Where is the nucleus situated in relation to the myelin sheath?
Between the myelin sheath and the neurilemma.
p.52
Types of Neurons and Nerve Fibers
What type of neuron is a vertebrate spinal motor neuron?
A type of neuron that transmits signals from the spinal cord to muscles.
p.96
Synaptic Transmission
What happens to Ca2+ ions when an action potential arrives at the synaptic terminal?
There is an influx of Ca2+ ions into the terminal.
p.15
Neuron Structure and Function
Do dendrites generate action potentials?
No, they generate local potentials instead.
p.54
Neuron Structure and Function
What is the function of sensory receptors?
They detect stimuli from the environment.
p.20
Myelination and Its Importance
Is the myelin sheath continuous?
No, it is absent at regular intervals.
p.16
Neuron Structure and Function
Where does branching occur in an axon?
Only at its terminal end, called synaptic knob, terminal button, or axon telodendria.
p.33
Neuroglia and Support Cells
How many glial cells are there compared to neurons?
There are 10 to 50 times as many glial cells as neurons.
p.83
Action Potential Mechanism
What type of channels respond to the depolarization in the adjacent membrane?
Voltage gated Na+ channels.
p.69
Resting Membrane Potential
What opposes the K+ equilibrium potential?
The Na+ equilibrium potential.
p.89
Myelination and Its Importance
How does myelin sheathing affect electrical charge flow in axons?
It improves the ability of electrical charge to flow far enough down the axon to reach the next node.
p.39
Neuroglia and Support Cells
What do microglia do when there is an injury or infection in the CNS?
They migrate to the injured or infected area and act as mature macrophages.
p.21
Myelination and Its Importance
What is the structure of Schwann cells before myelinogenesis?
They have a double layer close to the axolemma, similar to non-myelinated nerve fibers.
p.25
Neuron Structure and Function
What surrounds non-myelinated nerve fibers?
The neurilemma surrounds the axolemma continuously.
p.8
Neuron Structure and Function
What is a characteristic structure of sensory neurons?
Generally, they have a short axon and long dendrites.
p.3
Neuroglia and Support Cells
How many glial cells are there compared to neurons in the human CNS?
50 to 100 times the number of neurons.
p.27
Neuron Structure and Function
What is the first zone of a neuron?
Receptor or dendritic zone.
p.94
Synaptic Transmission
Where are synapses located in relation to neurons?
At the ends of the axon terminals where a presynaptic neuron contacts the dendrites or cell body of a postsynaptic cell.
p.83
Action Potential Mechanism
What happens when the activation gates of voltage gated Na+ channels open?
A new action potential is triggered in the adjacent membrane.
p.83
Action Potential Mechanism
Do action potentials decay in strength as they travel down the axon?
No, they do not decay in strength.
p.23
Myelination and Its Importance
How are non-myelinated nerve fibers covered?
They are simply covered by Schwann cells without wrapping.
p.29
Neuron Structure and Function
What is transported during anterograde transport?
Synaptic vesicles and proteins.
p.101
Synaptic Transmission
Which neurotransmitter is an inhibitory neurotransmitter in the central nervous system?
Gamma-aminobutyric acid (GABA).
p.37
Neuroglia and Support Cells
How do protoplasmic astrocytes support nerve cells?
They twist around nerve cells and form a supporting network in the brain and spinal cord.
p.52
Neuron Structure and Function
What is the role of the nucleus in a neuron?
It contains the genetic material and controls cellular activities.
p.12
Neuron Structure and Function
What structures are found in the cytoplasm of the nerve cell body?
Nucleus, Nissl bodies, neurofibrillae, mitochondria, and Golgi apparatus.
p.65
Nervous System Overview
What do the chemicals released by injured tissues stimulate?
Free nerve endings in the skin.
p.4
Neuron Structure and Function
What is a significant difference between neurons and other cells regarding division?
Neurons have no centrosome, resulting in a loss of power of division.
p.15
Neuron Structure and Function
What do dendrites and soma together constitute?
The input zone of the neuron.
p.54
Neuron Structure and Function
What is the function of interneurons?
They connect sensory and motor neurons within the central nervous system.
p.29
Neuron Structure and Function
What characterizes fast axonal transport?
It transports membrane-bound organelles and mitochondria at a rate of 400 mm/day.
p.27
Neuron Structure and Function
What occurs in the receptor or dendritic zone?
Multiple local potentials generated by synaptic connections are integrated.
p.54
Neuron Structure and Function
What are effectors?
They are muscles or glands that respond to motor neuron signals.
p.21
Myelination and Its Importance
When does myelinogenesis start for peripheral nerves?
In the 4th month of utero.
p.90
Myelination and Its Importance
How do myelinated neurons compare to non-myelinated neurons in terms of conduction speed?
Myelinated neurons conduct faster than non-myelinated neurons.
p.45
Types of Neurons and Nerve Fibers
What functions are primarily associated with long axons?
Proprioceptive, pressure and touch sensation, and somatic motor functions.
p.70
Resting Membrane Potential
What is the significance of resting potential in neurons?
It sets the stage for action potentials and nerve impulse conduction.
p.90
Myelination and Its Importance
What is the relationship between the cross-sectional area of a neuron and its ability to conduct electrical charge?
The larger the cross-sectional area, the further it can conduct electrical charge along the axon.
p.37
Synaptic Transmission
How do protoplasmic astrocytes affect neurotransmitter levels?
They regulate neurotransmitter levels in synapses and recycle neurotransmitters during synaptic transmission.
p.25
Neuron Structure and Function
What happens to the neurilemma at the node of Ranvier?
It invaginates up to the axolemma.
p.54
Neuron Structure and Function
What role do sensory neurons play in the nervous system?
They transmit sensory information to the central nervous system.
p.69
Resting Membrane Potential
How can the K+ equilibrium potential be calculated?
Using the Nernst equation.
p.33
Neuroglia and Support Cells
What are Schwann cells?
They are a type of glial cell that invest axons.
p.29
Neuron Structure and Function
What are the requirements for axonal transport?
It requires ATP, Ca++, and microtubules for guidance.
p.13
Neuron Structure and Function
Where are Nissl granules found in a neuron?
In the cell body and dendrites, but absent in the axon and axon hillock.
p.34
Neuroglia and Support Cells
What is the function of satellite cells?
Support and protect neuronal cell bodies in the peripheral nervous system.
p.11
Neuron Structure and Function
What direction do dendrites bring impulses?
Centripetally (towards the soma).
p.27
Action Potential Mechanism
Where is the initial segment of the action potential generated in a spinal motor neuron?
At the initial segment of the spinal motor neuron.
p.13
Neuron Structure and Function
Who discovered Nissl granules?
Franz Nissl in the 19th century.
p.37
Neuroglia and Support Cells
What is one of the primary functions of protoplasmic astrocytes?
To form the blood-brain barrier and regulate the entry of substances from blood to brain tissue.
p.45
Types of Neurons and Nerve Fibers
What sensations are small axons primarily concerned with?
Pain and temperature sensation, as well as autonomic functions.
p.68
Resting Membrane Potential
How much more permeable is K⁺ compared to Na⁺?
K⁺ is about 50 times more permeable than Na⁺.
p.11
Neuron Structure and Function
Can dendrites be absent in a neuron?
Yes, dendrites may be absent, one, or many.
p.12
Neuron Structure and Function
What does the nerve cell body maintain?
The functional and anatomical integrity of the axon.
p.12
Neuron Structure and Function
Where are somas present in the nervous system?
In the grey matter of the CNS, nuclei of the brain, and ganglia of the CNS.
p.52
Neuron Structure and Function
What is the cell body or soma?
The part of the neuron that contains the nucleus and organelles.
p.25
Neuron Structure and Function
What is unique about the nuclei of Schwann cells?
They are flattened and elongated.
p.12
Neuron Structure and Function
What is unique about Nissl granules and neurofibrillae?
They are found only in nerve cells, not in other cells.
p.70
Resting Membrane Potential
What role do ion channels play in resting potential?
They allow selective permeability of ions, contributing to the resting membrane potential.
p.52
Synaptic Transmission
What is the function of presynaptic terminals?
They release neurotransmitters into the synaptic cleft.
p.37
Neuroglia and Support Cells
What do protoplasmic astrocytes maintain around CNS neurons?
The chemical environment of the extracellular fluid (ECF).
p.90
Myelination and Its Importance
How can small diameter neurons conduct impulses rapidly?
Through myelination, which enhances conduction speed.
p.12
Neuron Structure and Function
What are the various shapes of nerve cell bodies?
Stellate, round, and pyramidal.
p.52
Myelination and Its Importance
What is the function of the myelin sheath?
To insulate the axon and increase the speed of nerve impulse conduction.
p.90
Myelination and Its Importance
What adaptation do invertebrates use to speed up conduction in the absence of myelinated neurons?
They increase axon diameter.
p.37
Neuroglia and Support Cells
What ions do protoplasmic astrocytes provide and regulate?
Calcium (Ca+) and potassium.
p.52
Synaptic Transmission
What are axon terminals?
The endpoints of an axon where neurotransmitters are released.
p.52
Action Potential Mechanism
What is the axon hillock?
The region where the axon begins and action potentials are initiated.
p.12
Neuron Structure and Function
Do all neurons contain a soma?
Yes, all neurons contain a soma.
