The Nervous System Flashcards
What is the Nervous System?
The body’s communication network that transmits and processes information between the brain and other body parts.
Define:
Central Nervous System
The body’s coordinating center for mechanical and chemical actions; it consists of the brain and spinal cord that integrates and coordinates sensory and motor functions.
What is the function of the brain?
The brain serves as the control center of the nervous system, responsible for perception, thought, emotion, and bodily functions.
Explain the role of the spinal cord.
The spinal cord is a long, thin, tubular bundle of nerves that extends from the brainstem down the back and serves as a pathway for nerve impulses between the brain and the body.
Fill in the Blank:
The ______________ Nervous System is the network of nerves outside the central nervous system that connects the brain and spinal cord to the rest of the body.
The Peripheral Nervous System is the network of nerves outside the central nervous system that connects the brain and spinal cord to the rest of the body.
True or False…
The Somatic Nervous System controls involuntary movements and sensory information from the body’s external environment.
False; the Somatic Nervous System controls VOLUNTARY movements and sensory information.
Define:
Sensory (Afferent)
Sensory or afferent relates to the senses or perception, such as touch, taste, smell, sight, and hearing.
What is the Motor (Efferent) function?
Motor or efferent relates to movement or muscle control, responsible for executing voluntary and involuntary actions.
Explain the role of the Autonomic Nervous System.
The Autonomic Nervous System is responsible for regulating involuntary bodily functions such as heart rate, digestion, and respiratory rate.
What is the function of the Sympathetic part of the Autonomic Nervous System?
The Sympathetic part prepares the body for fight or flight responses during stress or danger.
Define:
Parasympathetic
Parasympathetic is the part of the autonomic nervous system that helps the body to rest and recover by conserving energy and promoting digestion and relaxation.
What are Neurons?
Neurons are the functional units of the nervous system that conduct nerve impulses when a threshold is reached.
What are Dendrites?
Dendrites are branch-like extensions of a neuron that receive signals from other neurons or sensory receptors.
Define:
Neuron Cell Body
The Cell Body is the central part of a neuron that contains the nucleus and other organelles, functioning as the control center of the cell.
What is the function of an Axon?
An Axon is a long, slender projection of a neuron that carries nerve impulses away from the cell body, serving as the communication highway of the nervous system.
Explain the role of Schwann Cells.
Schwann Cells are specialized cells that wrap around and provide insulation to axons in the peripheral nervous system, resembling protective sheaths for efficient signal transmission.
What is a Myelin Sheath?
A Myelin Sheath is a fatty, insulating layer surrounding certain axons that speeds up the transmission of nerve impulses, functioning like an electrical wire insulation for efficient signal conduction.
Fill in the blank:
The part of the autonomic nervous system that prepares the body for fight or flight responses during stress or danger is the _______.
The part of the autonomic nervous system that prepares the body for fight or flight responses during stress or danger is the sympathetic
True or False…
The parasympathetic part of the autonomic nervous system helps the body to rest, recover, and promotes digestion and relaxation.
True
Define:
Neurons
Neurons are the functional units of the nervous system that conduct nerve impulses when a threshold is reached.
What are the three main parts of a neuron?
- Dendrites
- Cell Body
- Axon
Define:
Dendrites
Dendrites are branch-like extensions of a neuron that receive signals from other neurons or sensory receptors.
Fill in the blank:
The _______ is the central part of a neuron that contains the nucleus and other organelles, functioning as the control center of the cell.
The cell body is the central part of a neuron that contains the nucleus and other organelles, functioning as the control center of the cell.
Define:
Axon
An axon is a long, slender projection of a neuron that carries nerve impulses away from the cell body, serving as the communication highway of the nervous system.
What is the function of a Schwann Cell?
A Schwann Cell is a specialized cell that wraps around and provides insulation to axons in the peripheral nervous system, resembling protective sheaths for efficient signal transmission.
Fill in the blank:
The _______ is a fatty, insulating layer surrounding certain axons that speeds up the transmission of nerve impulses.
The myelin sheath is a fatty, insulating layer surrounding certain axons that speeds up the transmission of nerve impulses.
What is the Node of Ranvier?
The Node of Ranvier refers to the gaps in the myelin sheath along the axon where the axon membrane is exposed, allowing for faster propagation of nerve impulses.
What is the function of the Axon Terminal?
The Axon Terminal is the end of an axon that forms synapses with other neurons or effector cells, enabling the transmission of nerve impulses to target cells.
What is the primary role of Sensory (afferent) neurons?
Sensory (afferent) neurons relay information or stimuli received by sensory receptors about the internal and external environment to the central nervous system for processing.
How do Motor (efferent) neurons function in the nervous system?
Motor (efferent) neurons relay information to the effectors (the cell or organ that responds to the stimulus). Muscles, organs, and glands are classified as effectors as they produce responses.
What is the purpose of an Interneuron?
An Interneuron links neurons to other neurons, they are found only in the brain and spinal cord, and they integrate and interpret the sensory information and connect to outgoing motor neurons.
Explain the concept of a Reflex Arch.
A Reflex Arch is the simplest nerve pathway, which is involuntary and unconscious. It does not require coordination by the brain. It consists of a Receptor, sensory neuron, interneuron, motor neuron, and effector.
What is the Resting Potential in a neuron?
The Resting Potential refers to the voltage difference across the nerve cell membrane when it’s not actively firing an action potential. It is usually around -70 millivolts
What is the meaning of depolarization?
Depolarization refers to the process during the firing of a neuron when the neuron’s charge becomes less negative or even positive due to the influx of positively charged sodium ions.
Define:
Action Potential
Action Potential is the change in electrical potential associated with the passage of an impulse along the membrane of a neuron. It’s essentially the “firing” of the neuron.
What is Repolarization in the context of a neuron’s activity?
Repolarization is the return of the cell membrane potential to resting potential after the peak of the action potential has been reached. It’s mainly due to the outflow of positively charged potassium ions from the cell.
What is Hyperpolarization in a neuron’s activity?
Hyperpolarization is the increase in the membrane potential of a cell relative to its normal resting potential. It makes the inside of the neuron more negative and is usually due to the outflow of potassium ions or the inflow of chloride ions.
What is the Refractory Period in a neuron’s activity?
The Refractory Period is the time after an action potential during which the neuron is resistant to another action potential. It ensures the one-way transmission of nerve impulses.
What is the meaning of Saltatory Conduction?
Saltatory Conduction is the process by which nerve impulses jump from one Node of Ranvier to the next along a myelinated axon, significantly speeding up the propagation of the action potential.
Define:
Synapse
A Synapse is the junction between two neurons or a neuron and an effector cell, where electrical or chemical signals are transmitted.
Describe the process and significance of repolarization during an action potential.
Repolarization is the process where the neuron returns to its resting membrane potential after an action potential. It’s achieved by the opening of voltage-gated potassium channels and the outflow of potassium ions. This restores the negative charge inside the neuron, allowing it to potentially fire another action potential.
How do Glial Cells contribute to the function of the nervous system?
Glial cells support and protect neurons in the nervous system. They provide physical and nutritional support, participate in the immune response of the nervous system, produce and maintain the myelin sheath around axons, and regulate the extracellular fluid around neurons.
How does the myelin sheath contribute to the function of neurons?
The myelin sheath, produced by glial cells (Oligodendrocytes in the CNS and Schwann Cells in the PNS), wraps around the axon of neurons. It acts as an insulator and increases the speed of electrical signal transmission along the axon by allowing the action potential to jump between gaps in the myelin sheath, a process known as saltatory conduction.
How does the voltage-gated ion channel mechanism contribute to the “all or nothing” nature of an action potential?
Voltage-gated ion channels open when the membrane potential reaches a certain threshold. If the threshold is not reached, the channels remain closed, and no action potential is generated. However, once the threshold is reached, a full action potential is triggered regardless of the strength of the stimulus.
Describe the role of the sodium-potassium pump in the aftermath of an action potential. Why is it crucial for neuron function?
The sodium-potassium pump works to restore the resting membrane potential following an action potential by actively transporting three sodium ions out of the neuron for every two potassium ions it brings in. This helps maintain the electrochemical gradient necessary for the neuron to fire subsequent action potentials.
What would happen if a neuron’s voltage-gated sodium channels failed to close during the action potential? How would this affect the neuron’s ability to transmit signals?
If the voltage-gated sodium channels didn’t close, the neuron would remain depolarized because sodium ions would continue to flow into the cell. This would prevent the neuron from repolarizing and entering the refractory period, effectively inhibiting the neuron’s ability to transmit further action potentials.
Why is saltatory conduction faster than continuous conduction along an unmyelinated axon? How does this impact the overall efficiency of signal transmission?
Saltatory conduction is faster because it allows the action potential to jump from one node of Ranvier (gap in the myelin sheath) to the next, rather than traveling continuously along the entire length of the axon. This increases the speed of signal transmission and reduces the metabolic cost for the neuron, as less energy is required to restore the resting membrane potential.
What are synapses
Small spaces connecting neurons (between neurons and effectors) where neurotransmitters are released, allowing communication between neurons.
True or False…
Terminal branches of one neuron may join with many different neurons.
True
What is the role of neurotransmitters in the nervous system?
Neurotransmitters are chemicals released from the end plates of axon terminals that diffuse across the synaptic cleft, bind to receptors, and depolarize dendrites on the postsynaptic neuron, facilitating communication between neurons.
What happens when the space between neurons increases?
Although the space is small (~20 nm), when it increases, diffusion across synapses becomes relatively slow, resulting in slower speed of transmission.
Fill in the blank:
Acetylcholine is an _______ neurotransmitter
Acetylcholine is an excitatory neurotransmitter
How does acetylcholine work?
The neurotransmitter works by opening Na+ channels, found in most nerve cells. Once Na+ channels open, Na+ rush into postsynaptic neuron, resulting in depolarization → action potential → nerve impulse
Define:
Cholinesterase and its function.
Cholinesterase is an enzyme released by the presynaptic membrane that destroys acetylcholine, allowing the Na+ channels to close and the neuron to enter a recovery stage.
What is the function of inhibitory neurotransmitters in the nervous system?
Inhibitory neurotransmitters make the postsynaptic membrane more permeable to K+, causing hyperpolarization and inhibiting action potentials.
Fill in the blank:
Dopamine is a neurotransmitter that affects the brain synapse in control of _______, _______ and _______.
Dopamine is a neurotransmitter that affects the brain synapse in control of body movement, reward, and most notably pleasure.
Fill in the blank:
Serotonin is a neurotransmitter that regulates _______, _______ and is involved in _______ control.
Serotonin is a neurotransmitter that regulates temperature, sensory perception, and most notably mood control
What are endorphins and their function in the nervous system?
Endorphins are neurotransmitters that act as natural painkillers in the brain synapses and affect emotional areas of the brain.
Fill in the blank:
Norepinephrine is a neurotransmitter that complements the actions of _______, which readies the body to respond to danger or other stressful situations.
Norepinephrine is a neurotransmitter that complements the actions of epinephrine which readies the body to respond to danger or other stressful situations.
What are neurotoxins and their effect on the nervous system?
Neurotoxins like botulinum and tetanus are bacterial proteins that inhibit the release of essential neurotransmitters at nerve endings, disrupting the nervous system function.
Define:
Summation
Summation is the effect in the postsynaptic neuron produced by the accumulation of neurotransmitters from two or more neurons.
Name the three protective layers surrounding the brain and spinal cord.
The meninges: dura mater (outer layer), arachnoid mater (middle layer), and pia mater (inner layer)
What is the function of cerebrospinal fluid in the nervous system?
Cerebrospinal fluid acts as a shock absorber and transport medium, carrying nutrients to and removing wastes from the central nervous system.
What is meningitis and how is it diagnosed?
Meningitis is inflammation of the meninges caused by a bacterial or viral infection. It can only be diagnosed by examining a sample of the fluid surrounding the brain and spinal cord.
Fill in the blank:
The spinal cord consists of two types of nerve tissue: _______ & _______ matter.
The spinal cord consists of two types of nerve tissue: grey & white matter.
What is the function of the cerebrum in the brain?
The cerebrum acts as a major coordinating centre from which sensory information and motor actions originate.
Fill in the blank:
The right hemisphere of the cerebrum is associated with _________ & _________, while the left hemisphere is linked to _______.
The right hemisphere of the cerebrum is associated with visual patterns & spatial awareness while the left hemisphere is linked to verbal skills
The hypothalamus in the brain plays a large role in maintaining the body’s internal equilibrium. How does it connect the nervous and endocrine systems?
The hypothalamus’s direct connection with the pituitary gland unites the nervous and endocrine systems.
Fill in the blank:
The cerebellum, located in the hindbrain, controls _______, _______, and _______.
The cerebellum, located in the hindbrain, controls limb movements, balance, and muscle tone
The frontal lobe of the brain is responsible for _______, and its association areas are linked to _______, _______, _______, and _______.
The frontal lobe of the brain is responsible for Motor control, and its association areas are linked to intellect, memory, emotions, and personality
Define:
Association areas (in the context of different parts of the brain)
Association areas in the brain are regions that aren’t involved in the processing of sensory information or the control of motor functions. Instead, these areas are involved in more complex processes that integrate information from different parts of the brain to support higher cognitive functions.
True or False…
The parietal lobe of the brain is associated with vision and interpretation of visual information.
False; the occipital lobe is associated with vision and interpretation of visual information.
What are MRI, CT, and PET scans used for?
They are non-invasive tools used to map human brain function and screen for diseases.
Explain the process of transmission in the nervous system.
- Action potential reaches presynaptic terminal
- Voltage-gated Ca2+ channels open
- Influx of Ca2+
- Synaptic vesicles fuse with membrane (exocytosis)
- Neurotransmitters released into synaptic cleft and diffuse to postsynaptic terminal
- Neurotransmitters bind to receptor on postsynaptic membrane
- If threshold is reached, action potential is initiated
- Neurotransmitter is broken down by specific enzymes in synaptic cleft.
What is the role of the “blood-brain barrier” in protecting the CNS?
The blood-brain barrier is a unique property of the blood vessels that vascularize the CNS. It allows them to tightly regulate the movement of ions, molecules, and cells between the blood and brain.
True or False…
The spinal cord emerges from the skull through an opening called the foramen magnum.
True
Fill in the blank:
The _______ root brings sensory information into the spinal cord, while the _______ root carries motor information from the spinal cord to the peripheral nervous system.
The dorsal root brings sensory information into the spinal cord, while the ventral root carries motor information from the spinal cord to the peripheral nervous system.; ventral
Fill in the blanks:
The forebrain consists of the _______, _______, and _______.
The forebrain consists of the cerebrum, hypothalamus, olfactory bulbs.
What is the function of the thalamus in the brain?
The thalamus acts as a relay station for sensory information going to the cerebrum.
The midbrain, located just below the thalamus, acts as a relay centre for what type of reflexes?
Some eye and ear reflexes.
What is the role of the pons in the hindbrain?
The pons acts as a relay station for regions of the cerebellum and between the cerebellum and medulla.
What are the main functions of the medulla oblongata?
The medulla oblongata controls involuntary muscle action (like breathing, heart rate, etc.) and acts as the coordination centre for the autonomic nervous system.
Fill in the blank:
The temporal lobe of the brain processes _______ information and its association areas are linked to _______ and _______.
The temporal lobe of the brain processes auditory/sound/hearing (and some visual) information and its association areas are linked to visual and verbal memory, emotions, learning and interpretation of language
Fill in the blank:
The sensory areas of the parietal lobe are associated with _______ and _______ awareness.
The sensory areas of the parietal lobe are associated with touch and temperature awareness.
Fill in the blank:
The lateral ventricle is one of many ventricles that produce and store _______.
The lateral ventricle is one of many ventricles that produce and store cerebrospinal fluid
What is myopia?
It is a condition where an individual can see close objects, but not far ones, caused by the eyeball being “stretched” wider
What is hyperopia?
It is a condition where an individual cannot see close objects, but can’t see far ones, caused by the eyeball being “stretched” longer
What is astigmatism?
It is a condition where are the uneven shape of the cornea impairs the ability to focus light properly 
