What is the primary function of the nervous system in human beings?
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It serves as the master control and communication system of the body.
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What is the primary function of the nervous system in human beings?
It serves as the master control and communication system of the body.
What role does the nervous system play in decision making?
It is involved in processing information for decision making.
What is the role of neuroglia in the PNS?
They completely surround axons and cell bodies.
What do Schwann cells produce?
The myelin sheath that surrounds the axons of peripheral nerves.
What is the primary function of a synapse?
To transmit signals between neurons.
How do Schwann cells affect axon conduction?
They insulate the axons and increase their conduction.
What is an action potential?
A rapid change in membrane potential that propagates along a neuron.
What is one function of Schwann cells related to injury?
They guide the regrowth of damaged axons.
What triggers the generation of an action potential?
A sufficient depolarization of the neuron's membrane.
What do satellite cells do?
They enclose the cell bodies of peripheral neurons and regulate their internal environment.
What role do neurotransmitters play in synaptic transmission?
They are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron.
What protective function do satellite cells provide?
They provide a protective coat around the cell bodies of peripheral neurons.
What happens during the depolarization phase of an action potential?
Sodium channels open, allowing Na+ ions to enter the neuron.
What is the role of potassium channels during an action potential?
They open to allow K+ ions to exit the neuron, repolarizing the membrane.
What is the refractory period?
A period during which a neuron cannot generate another action potential.
What is the charge distribution inside and outside most cells?
Most cells are negatively charged inside, while the extracellular space is positively charged.
How does the synapse contribute to signal integration?
By summing excitatory and inhibitory signals from multiple neurons.
What stimulates the adjacent region in impulse conduction?
An action potential in one region.
What is the term used to describe the difference in charges across a cell membrane?
Polarity.
What are the two divisions of the Peripheral Nervous System (PNS)?
Sensory and motor divisions.
What are satellite cells?
Flat cells that surround the cell bodies of neurons in PNS ganglia.
What are astrocytes?
Star-shaped cells that are the largest and most numerous of all glial cells.
What are the two main types of matter found in the cross section of the human brain and spinal cord?
White matter and gray matter.
What is the process called when a neuron changes from a negative to a positive charge?
Depolarization.
What does the local current do in the context of action potentials?
It stimulates the adjacent axon membrane to its threshold level, triggering another action potential.
What is the primary function of the nervous system in humans?
To coordinate and control body activities and respond to internal and external stimuli.
What is membrane potential?
The potential for charges to move across the cell membrane.
What does the sensory, or afferent division do?
Brings information into the Central Nervous System (CNS).
What percentage of cells in certain regions of the brain are astrocytes?
90%.
What do satellite cells regulate?
The exchange of materials between neuronal cell bodies and interstitial fluid.
What happens when neurotransmitter molecules bind to receptors on a postsynaptic cell?
They can have either an excitatory or inhibitory effect.
What is the primary function of gray matter in the brain and spinal cord?
Gray matter is involved in processing and integrating information.
What occurs along the axon as a result of action potentials?
A series of action potentials.
What structure provides protection against collisions for the spinal cord?
The vertebral column.
What type of response does the action potential exhibit?
All-or-none response.
What happens when charges flow from one area to another?
They create an electrical current.
What are the two main divisions of the human nervous system?
The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
What happens when an action potential reaches the membrane of a synaptic knob?
It increases the membrane’s permeability to calcium ions by opening calcium ion channels.
What are microglia?
Small 'spider-shaped' cells scattered in the CNS.
What do sensory receptors do?
Gather information by detecting changes inside and outside the body.
What surrounds the brain and spinal cord?
Cerebrospinal fluid (CSF).
What is one of the primary functions of astrocytes?
Preventing capillary leakage.
What are Schwann cells?
Flat cells that encircle PNS axons and form the myelin sheath around them.
What is divergence in the context of neuronal pools?
Divergence occurs when a neuron synapses with several other neurons, allowing an impulse to stimulate multiple neurons.
Where are ganglia located?
Outside the CNS, consisting of collections of neuronal cell bodies.
What is the effect of an excitatory neurotransmitter?
It stimulates an impulse.
What is the primary function of the nervous system in human beings?
To coordinate and control body activities and respond to internal and external stimuli.
What is the primary function of white matter in the brain and spinal cord?
White matter is responsible for transmitting signals between different regions of the brain and spinal cord.
How does a nerve impulse travel once begun?
At a constant strength.
What are the protective membranes that lie between the bony encasement and the nervous tissue?
Meninges.
What happens after depolarization in a neuron?
There is a quick return to the resting membrane potential.
What components make up the Central Nervous System (CNS)?
The brain and spinal cord.
What are the three structural classifications of neurons?
Multipolar, bipolar, and unipolar neurons.
What occurs after calcium ions diffuse inward during synaptic transmission?
Some synaptic vesicles fuse with the membrane and release neurotransmitter molecules into the synaptic cleft.
What does the motor division of the PNS do?
Conducts impulses from the CNS to effectors.
From which cells do microglia develop?
From white blood cells (monocytes).
What are neurons?
The fundamental units of the brain and nervous system responsible for receiving sensory input and sending motor commands.
What types of changes do sensory receptors detect?
External environmental factors (e.g., light, sound) and the body's internal environment (e.g., temperature, oxygen level).
Where does cerebrospinal fluid occupy?
The subarachnoid space of the meninges.
How do astrocytes contribute to the blood-brain barrier (BBB)?
They help maintain the integrity of the BBB.
How many unmyelinated axons can a single Schwann cell enclose?
As many as 20 or more.
What are the two main divisions of the nervous system?
The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
How does divergence amplify an impulse?
Divergence spreads an impulse to more neurons in the pool, increasing its overall effect.
What is a synapse?
A connection between two neurons, which is the site of nerve signal transmission.
What are the three layers of the meninges?
The dura mater, arachnoid mater, and pia mater.
What is the primary function of sensory neurons?
To conduct impulses from peripheral body parts into the brain or spinal cord.
What are neurons?
Nerve cells that transmit impulses in the nervous system.
What is the role of neurotransmitters in synaptic transmission?
They can be either excitatory or inhibitory.
What type of signal travels along the surface of the membrane of a neuron?
An electrical signal.
What is one function of satellite cells?
Providing structural support to neuronal cell bodies.
What are oligodendrocytes aligned along?
Axons of neurons.
What are neurons specialized for?
To transmit messages (nerve impulses) from one part of the body to another.
What is the effect of an inhibitory neurotransmitter?
It prevents an impulse.
What is the function of cerebrospinal fluid (CSF)?
It acts as a shock absorber and hydraulic cushion.
What occurs during repolarization?
Potassium channels open, allowing potassium to rush out of the cell.
What is the role of the Peripheral Nervous System (PNS)?
To connect the CNS to the limbs and organs, facilitating communication.
Where are most multipolar neurons located?
Within the brain or spinal cord.
What do neurotransmitter molecules do after being released into the synaptic cleft?
They diffuse across the synaptic cleft and may bind to specific receptors on the postsynaptic cell.
What is one of the primary functions of microglia?
Act as phagocytes to remove bacterial cells and cellular debris.
What are effectors?
Responsive structures that cause a response, such as muscles and glands.
What do neurons use to send signals?
Nerve impulses (electrical signals).
What is the function of cerebrospinal fluid?
To support and protect the brain and spinal cord by absorbing forces.
What do astrocytes regulate in neurons?
Ions and nutrients.
What role do Schwann cells play in axon regeneration?
They participate in axon regeneration, which is easier in the PNS than in the CNS.
What is the outermost layer of the meninges?
The dura mater.
What is the significance of divergence in the CNS?
It allows the effect of a single neuron to be amplified, enabling impulses to reach enough motor units for forceful muscle contraction.
What does the Central Nervous System consist of?
The brain and spinal cord.
Are the pre-synaptic and post-synaptic neurons in direct physical contact?
No, they are separated by a gap called the synaptic cleft.
What specialized structures do sensory neurons have?
Specialized receptor ends at the tips of their dendrites.
What happens during an inhibitory stimulus?
Cl– ions flow in or K+ ions flow out, making the charge more negative.
What is the function of the cell body in a neuron?
It maintains the proper diameter of the axon for impulse conduction.
What is the dura mater?
A strong, tubular sheath that surrounds the spinal cord.
What is the main difference between myelinated and unmyelinated axons?
Myelinated axons are covered with a myelin sheath, which increases the speed of nerve impulse transmission, while unmyelinated axons lack this sheath and transmit impulses more slowly.
What do oligodendrocytes produce?
Insulating layers known as the myelin sheath.
What determines the net effect on the postsynaptic cell?
The combined effect of excitatory and inhibitory inputs from presynaptic neurons.
What is the role of the vertebral column in relation to the spinal cord?
It provides protection against collisions.
What is reestablished after repolarization?
Polarity between both sides of the neuron.
How does the nervous system contribute to homeostasis?
By regulating bodily functions and maintaining internal balance.
What type of neurons are found in specialized parts of the eyes, nose, and ears?
Bipolar neurons.
What is the role of calcium ions in synaptic transmission?
Calcium ions facilitate the fusion of synaptic vesicles with the membrane to release neurotransmitters.
What are the three distinct parts of a neuron?
Cell body, dendrites, and axon.
What is the core structure of the spinal cord composed of?
Gray matter, which consists mostly of cell bodies and dendrites.
What is the primary function of the Nervous System?
To process sensory information and elicit appropriate responses.
What is the role of synapses in the nervous system?
They facilitate communication between neurons and the generation of action potentials.
What are the two categories of motor functions in the PNS?
Voluntary and involuntary.
How do microglia contribute to damaged areas in the CNS?
They form scars in damaged areas.
What are neuroglia?
A group of non-neuronal cells in the nervous system that support and protect neurons.
How does cerebrospinal fluid circulate?
Through the ventricles and central canal, entering the subarachnoid space, and being reabsorbed into the blood.
What is the role of the pre-synaptic neuron?
It is the impulse sender.
How does an inhibitory stimulus affect a neuron?
It makes the neuron less likely to get excited.
How does the dura mater relate to the vertebral canal?
It continues into the vertebral canal as a sheath.
What is the role of dendrites in neurons?
They provide a large surface area to receive information from other neurons.
What is the role of the myelin sheath?
It insulates the axon and prevents almost all ion movement.
How do Schwann cells compare to oligodendrocytes?
Both form myelin sheaths, but Schwann cells are in the PNS while oligodendrocytes are in the CNS.
How can sensory impulses utilize divergence?
An impulse from a sensory receptor may diverge to reach multiple regions of the CNS for processing and action.
What is the primary composition of the dura mater?
Tough, white, fibrous connective tissue.
What is the role of the Peripheral Nervous System?
To connect the CNS to the limbs and organs.
What triggers sensory impulses in sensory neurons?
Changes that occur inside or outside the body stimulate receptor cells.
How does the myelin sheath affect neural conduction speed in the CNS?
It increases the neural conduction speed.
How does myelination affect the conduction of action potentials?
Myelination allows for saltatory conduction, where action potentials jump between nodes of Ranvier, increasing the speed of transmission.
How many presynaptic neurons can influence a postsynaptic cell?
As few as 1 to as many as 10,000.
Where are the cell bodies of unipolar neurons located?
In ganglia, which are outside the brain and spinal cord.
What are the cell bodies of neurons in the gray matter called?
Horns.
What types of neuroglia are found in the Central Nervous System (CNS)?
Oligodendrocytes, astrocytes, ependymal cells, and microglia.
What is facilitation in the context of synapses?
Facilitation occurs when repeated impulses on an excitatory presynaptic neuron cause it to release more neurotransmitter in response to a single impulse, increasing the likelihood of reaching the postsynaptic cell's threshold.
What do sensory receptors detect?
Internal and external stimuli.
What is the spinal cord?
A column of nervous tissue that passes downward from the brain into the vertebral canal.
What are neuronal pools?
Groups of neurons organized in the CNS that make hundreds of synaptic connections with each other to perform common functions.
What disrupts continuous impulse conduction in myelinated axons?
The myelin sheath.
What does the dura mater contain?
Many blood vessels and nerves.
How does the nervous system contribute to homeostasis?
By regulating bodily functions and maintaining internal balance.
Which system controls voluntary (conscious) movements?
The somatic nervous system.
How do sensory impulses travel to the brain or spinal cord?
They travel along the sensory neuron axons.
What is the role of the post-synaptic neuron?
It is the impulse receiver.
What separates the dura mater from the vertebrae?
An epidural space.
What determines whether an action potential is triggered in a postsynaptic neuron?
If more excitatory than inhibitory neurotransmitters are released.
What role do microglia play in monitoring neurons?
They monitor the health of nearby neurons.
What do axons do?
They send impulses away from the cell body towards other neurons or cells.
What proportion of neural tissue volume do neuroglia represent?
About half the volume of neural tissue.
What is the role of the synapse in nerve communication?
The synapse is the junction where nerve impulses are transmitted from one neuron to another, allowing for communication between neurons.
What is the composition of the myelin sheath?
A multilayered lipid and protein covering.
What is a ganglion?
A specialized mass of nervous tissue where unipolar neuron cell bodies are found.
What is the function of the gray matter in the spinal cord?
It serves as an integrating and reflex processing center.
What types of neuroglia are found in the Peripheral Nervous System (PNS)?
Schwann cells and satellite cells.
What is convergence in neuronal pools?
Convergence is when a single neuron receives input from two or more incoming axons, allowing impulses from different sources to have an additive effect.
How many segments does the spinal cord consist of?
31 segments.
How is sensory information transmitted to the brain and spinal cord?
Through cranial and spinal nerves.
Where does conduction occur in a myelinated axon?
At the Nodes of Ranvier.
What happens when a neuron in a neuronal pool receives both excitatory and inhibitory inputs?
The net effect determines whether an outgoing impulse is triggered or not.
What does the autonomic nervous system control?
Effectors that are involuntary, such as cardiac muscle, smooth muscle, and various glands.
What is the common structural type of most sensory neurons?
Most sensory neurons are unipolar; some are bipolar.
What fills the synaptic cleft?
Interstitial fluid.
What does the epidural space contain?
Loose connective and adipose tissues.
What is an action potential?
An action potential is a rapid change in electrical potential across a neuron's membrane, allowing for the transmission of nerve impulses.
What is the overall effect of neurotransmitter activity in the nervous system?
A complex combination of excitation and inhibition.
What types of debris do microglia dispose of?
Dead brain cells and bacteria.
How do the structures of neurons vary?
They differ in structure, size, and shape.
Do neuroglia produce nerve impulses?
No, they do not produce nerve impulses.
What is the primary function of the myelin sheath?
To insulate axons and increase the speed of nerve impulse conduction.
What is a stimulus in the context of action potential?
Anything that can change the resting potential of –70 mV in either direction.
What forms the outer layer of the spinal cord?
White matter, formed by myelinated and unmyelinated axons.
How do neurons vary?
They vary in sizes and shapes.
What type of cells are ependymal cells?
Cuboidal to columnar cells.
What are the main structures of the human brain?
Cerebrum, cerebellum, and brainstem.
How does convergence affect neuronal function?
It allows impulses arriving from different sources to combine, potentially enhancing the overall response of the neuron.
What surrounds the organs of the Central Nervous System (CNS)?
Bones, membranes, and fluid.
What are the two main types of cells in the nervous system?
Neurons and neuroglia.
What is the integrative function of the nervous system?
To process sensory information by analyzing it and making decisions for appropriate responses.
What do the segments of the spinal cord give rise to?
A pair of spinal nerves.
What is the term for the jumping of an impulse from node to node?
Saltatory conduction.
What are the main functions of the nervous system?
Sensory input, integration, and motor output.
What is the role of neurotransmitters in synaptic transmission?
They carry out synaptic transmission by diffusing across the synaptic cleft.
What occurs if the net effect of inputs to a neuron is excitatory and reaches the threshold?
An outgoing impulse is triggered.
What type of process is synaptic transmission?
A one-way process, from presynaptic neuron to postsynaptic neuron.
What is the function of the tissues in the epidural space?
They pad the spinal cord.
What functions do neuroglia provide for neurons?
Protection, support, and insulation.
What happens to a released neurotransmitter in the synaptic cleft?
It is either decomposed or removed.
What is an action potential?
A rapid transitory and propagating change in the membrane potential, first positive, then negative, returning to resting potential.
What is the primary function of white matter in the spinal cord?
To pass information up and down the spinal cord.
What do ependymal cells line in the brain?
The cavities called ventricles.
What is the primary function of the cerebrum?
Responsible for higher brain functions such as thought and action.
Where does the brain lie?
In the cranial cavity of the skull.
What is the primary function of neurons?
To transmit electrical signals throughout the nervous system.
What are the main organs of the nervous system in humans?
The central nervous system (CNS) and the peripheral nervous system (PNS).
How does saltatory conduction benefit neurons?
It saves energy and speeds up the transmission of impulses.
What is the role of spinal nerves?
They branch to various body parts and connect them with the CNS.
What happens after sensory information is integrated?
The nervous system elicits an appropriate motor response by activating effectors.
What is the role of sensory neurons?
To transmit sensory input to the central nervous system.
What is the resting membrane potential of a neuron?
-70 mV (millivolts).
Where are most neurotransmitter molecules synthesized?
In the cytoplasm of the synaptic knobs.
What is the primary function of the spinal cord?
To transmit signals between the brain and the rest of the body.
What cannot cross the synaptic cleft?
Nerve impulse.
What happens if the net effect is excitatory but subthreshold?
An impulse is not triggered.
What is cerebrospinal fluid (CSF)?
A clear, colorless liquid composed primarily of water and small amounts of glucose, proteins, lactic acid, urea, and electrolytes.
Why is it important for neurotransmitters to be removed from the synaptic cleft?
To prevent continuous action on postsynaptic neurons.
What happens to neuroglia in case of injury?
They multiply to fill in the spaces formerly occupied by neurons.
What are the two main types of cells in the nervous system?
Neurons and neuroglia.
What are nerves composed of?
Bundles of axons located in the PNS.
What is produced by ependymal cells?
Cerebrospinal fluid (CSF).
What is the primary function of the blood-brain barrier?
To protect the brain from harmful substances while allowing essential nutrients to pass.
