Stanbridge - T1 - Physiology - W4 - Nervous System: Neurons and Action Potentials

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Questions and Answers

Which type of neuron is primarily responsible for transmitting impulses from sensory receptors to the central nervous system?

Efferent Neurons

Interneurons

Sensory Neurons (correct)

Motor Neurons

What is one primary role of astrocytes in the nervous system?

Conducting electrical impulses

Releasing neurotransmitters

Providing structural support (correct)

Forming the myelin sheath

Which of the following statements accurately differentiates between graded potentials and action potentials?

Graded potentials are all-or-nothing responses.

Graded potentials always lead to action potentials.

Action potentials are variable in amplitude.

Graded potentials decrease in strength over distance. (correct)

Which component is essential for the generation of an action potential?

Influx of sodium ions Signup and view all the answers

Which of the following cells is NOT classified as a type of neuroglia?

Dendrites Signup and view all the answers

What is the primary function of neurotransmitters in the nervous system?

Facilitating communication between neurons Signup and view all the answers

Which of the following statements best describes the structure of a motor neuron?

They are characterized by multiple dendrites. Signup and view all the answers

Which protective mechanism surrounds the central nervous system and helps maintain the blood-brain barrier?

Astrocytic end-feet Signup and view all the answers

What is the role of norepinephrine in neuronal communication?

It triggers action potentials in the next neuron. Signup and view all the answers

Which of the following brain regions contains the cerebral cortex?

Cerebrum Signup and view all the answers

What is a primary function of the blood-brain barrier?

To protect the brain from infectious agents and toxins. Signup and view all the answers

Which structure is primarily responsible for the integration of sensory and motor information?

Cerebellum Signup and view all the answers

What is the average weight of the human brain?

2.95 lbs for males and 2.64 lbs for females Signup and view all the answers

How long can the brain survive without oxygen before leading to unconsciousness?

10 seconds Signup and view all the answers

What happens to neurotransmitters after they have exerted their effect?

They are broken down by enzymes and taken up by endocytosis. Signup and view all the answers

Which of the following is NOT a major structure in the central nervous system (CNS)?

Liver Signup and view all the answers

What is the primary function of astrocytes in the central nervous system?

Support and brace neurons while controlling their environment Signup and view all the answers

Which characteristic differentiates action potentials from graded potentials?

Action potentials only occur in axons Signup and view all the answers

What effect does depolarization have on a neuron's membrane potential?

It decreases membrane potential making it less negative Signup and view all the answers

Which type of glial cell is responsible for forming myelin sheaths in the peripheral nervous system?

Schwann cells Signup and view all the answers

What property of neurons allows them to generate action potentials?

Excitable membranes Signup and view all the answers

What role do microglial cells play in the central nervous system?

Clear neural debris by acting as macrophages Signup and view all the answers

What must occur for an action potential to be initiated?

Sufficient depolarization to reach the threshold Signup and view all the answers

What is the function of ependymal cells in the central nervous system?

Line central cavities and circulate cerebrospinal fluid Signup and view all the answers

In regarding the blood-brain barrier, which of the following statements is true?

It maintains a stable environment for neurons Signup and view all the answers

What is the role of dendrites in a neuron?

Receive information and transmit it to the cell body Signup and view all the answers

Which of the following ions is primarily involved in the depolarization phase of an action potential?

Na+ Signup and view all the answers

What is a key difference between the functions of oligodendrocytes and Schwann cells?

Oligodendrocytes myelinate multiple axons, Schwann cells myelinate single axon Signup and view all the answers

Which process increases the permeability of the neuron's membrane to sodium ions during action potential generation?

Threshold depolarization Signup and view all the answers

What distinguishes the central nervous system (CNS) from the peripheral nervous system (PNS)?

The CNS is enclosed by bone, while the PNS is not. Signup and view all the answers

Which of the following accurately describes the role of interneurons?

Interneurons relay messages between other neurons within the CNS. Signup and view all the answers

Which glial cell type is involved in forming myelin in the central nervous system?

Oligodendrocytes Signup and view all the answers

What is the primary outcome when a neuron reaches the threshold potential during an action potential?

The neuron depolarizes rapidly. Signup and view all the answers

In what way do action potentials differ from graded potentials?

Action potentials are all-or-nothing events. Signup and view all the answers

Which ion primarily contributes to the repolarization phase of an action potential?

Potassium ions (K⁺) Signup and view all the answers

What role do astrocytes play in the functioning of the central nervous system?

They provide structural support and regulate the extracellular environment. Signup and view all the answers

Which type of stimulus can initiate an action potential in a neuron?

Both electrical and chemical stimuli Signup and view all the answers

Which statement about the brain's metabolic requirements is correct?

The brain requires a constant supply of glucose and oxygen. Signup and view all the answers

Which regions of the central nervous system are correctly identified?

Cerebrum, Diencephalon, Brainstem, and Cerebellum Signup and view all the answers

What is the weight range for the average adult human brain?

Approximately 2.64 to 2.95 pounds in males and females respectively Signup and view all the answers

Which statement regarding neurotransmitters is accurate?

They can be taken up by endocytosis after exerting their effects. Signup and view all the answers

Which component of the central nervous system is primarily responsible for the control of balance and coordination?

Cerebellum Signup and view all the answers

What is the consequence of the brain being deprived of oxygen for 10 seconds?

Loss of consciousness Signup and view all the answers

Which area does NOT comprise a major region of the central nervous system?

Neocortex Signup and view all the answers

What percentage of total blood flow is directed to the brain?

20% Signup and view all the answers

What is the primary function of the hypothalamus in the diencephalon?

Regulate body temperature Signup and view all the answers

Which part of the brainstem is primarily responsible for connecting the cerebellum to the brain?

Pons Signup and view all the answers

What mechanism allows myelinated axons to increase the speed of action potential conduction by about 30x?

The insulating properties of myelin Signup and view all the answers

What role does the epithalamus play in the human brain?

Regulation of sleep-wake cycles Signup and view all the answers

Which statement accurately describes the functions of the thalamus?

Sensory relay to the cortex Signup and view all the answers

Which characteristic distinguishes electrical synapses from chemical synapses?

Electrical synapses allow for synchronized activity. Signup and view all the answers

What is a crucial function of the basal nuclei in movement?

Inhibit unnecessary movements Signup and view all the answers

What event occurs during the repolarization phase of an action potential?

K+ exits the axon Signup and view all the answers

Which of the following structures serves as a continuation of the spinal cord?

Medulla Oblongata Signup and view all the answers

Which step in neurotransmitter release is immediately responsive to the arrival of the action potential at the axon terminal?

Calcium channels in the terminal open Signup and view all the answers

Which process converts an electrical signal to a chemical signal in the synapse?

Exocytosis of vesicles Signup and view all the answers

Which aspect of the brainstem is associated with reflexes of the eyes and ears?

Midbrain Signup and view all the answers

What body functions does the hypothalamus regulate for achieving homeostasis?

Sleep-wake cycles and body temperature Signup and view all the answers

What consequence occurs during hyperpolarization within an action potential?

The membrane potential becomes more negative than resting potential. Signup and view all the answers

What type of communication is characteristic of chemical synapses?

Unidirectional communication Signup and view all the answers

Which of the following accurately describes the role of neurotransmitters?

They facilitate communication between neurons by binding to receptors. Signup and view all the answers

Which statement is true about the sodium-potassium pump during an action potential?

It maintains the resting potential by transporting Na+ out. Signup and view all the answers

What role does calcium (Ca2+) play at the axon terminal during neurotransmitter release?

It facilitates the movement of neurotransmitter vesicles to the membrane. Signup and view all the answers

What is the primary function of commissural fibers in the cerebral white matter?

Connect corresponding gray matter of two hemispheres Signup and view all the answers

Which area of the cerebral cortex is primarily associated with complex learning and personality traits?

Anterior association area Signup and view all the answers

What is the role of the basal nuclei in the brain?

Filter out inappropriate responses and monitor movement intensity Signup and view all the answers

What do the projection fibers in the cerebral white matter primarily connect?

Higher brain areas with the spinal cord and lower brain areas Signup and view all the answers

Which component of the brain is associated with recognizing patterns and faces?

Posterior association area Signup and view all the answers

What are association fibers responsible for in the cerebral white matter?

Connecting different parts within a single hemisphere Signup and view all the answers

Which structure is part of the limbic association area and plays a significant role in memory?

Hippocampus Signup and view all the answers

What characterizes the corona radiata in relation to projection fibers?

It forms a branch of fibers radiating from the internal capsule Signup and view all the answers

Which of the following is NOT a function of the anterior association area?

Recognition of self in space Signup and view all the answers

What primarily distinguishes the roles of projection fibers from association fibers in the cerebral white matter?

Projection fibers transmit impulses to and from lower brain areas, while association fibers connect different parts in a hemisphere Signup and view all the answers

What is the primary function of the axon in a neuron?

Conducts impulses away from the cell body Signup and view all the answers

Which of the following functions is NOT attributed to astrocytes?

Forming the myelin sheath around axons Signup and view all the answers

What is the role of microglial cells in the central nervous system?

To monitor neuron health and remove debris Signup and view all the answers

What significant change occurs during depolarization?

The membrane potential briefly reverses, becoming positive Signup and view all the answers

Which of the following statements accurately reflects the action potential process?

Action potentials occur as an all-or-none event along the axon Signup and view all the answers

What role do ependymal cells play in the central nervous system?

Line the central cavities and circulate cerebrospinal fluid Signup and view all the answers

How do Schwann cells function in the peripheral nervous system?

Creating myelin sheaths and aiding in nerve regeneration Signup and view all the answers

In resting membrane potential, which ion has a higher concentration outside the cell compared to inside?

Na+ (Sodium) Signup and view all the answers

What distinguishes oligodendrocytes from Schwann cells?

Oligodendrocytes form myelin in the CNS, Schwann cells in the PNS Signup and view all the answers

What characteristic of neurons allows them to generate an action potential?

The existence of excitable membranes Signup and view all the answers

During hyperpolarization, which of the following occurs?

The internal potential further decreases beyond the resting potential Signup and view all the answers

What is the primary role of dendrites in a neuron?

Receiving information and transmitting it to the cell body Signup and view all the answers

Which statement is true regarding graded potentials?

They can vary in magnitude and duration Signup and view all the answers

What effect does the refractory period have on action potentials?

It prevents backward propagation of action potentials Signup and view all the answers

What is one characteristic feature of action potentials?

They are always triggered by depolarization reaching a specific threshold Signup and view all the answers

Study Notes

Nervous System: Neurons and Action Potentials

The nervous system is composed of the central nervous system (CNS) and the peripheral nervous system (PNS).
The CNS includes the brain and spinal cord.
The PNS includes cranial nerves, spinal nerves, and ganglia.
Glial cells support neurons. Types include astrocytes, ependymal cells, Schwann cells, oligodendrocytes, microglia, and satellite cells.
Neurons are the basic structural and functional units of the nervous system. They respond to stimuli, conduct electrochemical impulses, and release chemical regulators.
Types of neurons include motor, sensory, and interneurons.
Neurons have dendrites, an axon hillock, a cell body, and an axon.
The parts of a neuron communicate via electrochemical signals.
Myelin sheaths insulate axons.
Myelin ensures faster action potentials by saltatory conduction.
Multipolar, bipolar, and unipolar are types of neurons classified by their structure.
Electrical synapses connect adjacent neurons through gap junctions.
The speed of electrical signals depends on the type of neuron.
Chemical synapses release neurotransmitters.
Steps of an action potential from a chemical synapse involve: depolarization, repolarization, and hyperpolarization.
Different neurotransmitters have different roles in the nervous system.
Neurons communicate with each other via action potentials generated from electrical and chemical signals.

Central Nervous System (CNS)

The CNS is composed of the brain and spinal cord.
The brain has five major regions: cerebrum, diencephalon, cerebellum, and brainstem (midbrain, pons, medulla oblongata). The spinal cord is located below the brainstem.
The brain has approximately 100 billion neurons.
The brain has high metabolic demands and requires a constant supply of oxygen and glucose.
Gray matter is composed of cell bodies and dendrites, while white matter consists primarily of axons.
White matter tracts in the brain include association fibers, commissural fibers, and projection fibers.
The five brain regions are involved in sensation, communication, memory, motor functions, emotions, cognition, and the regulation of the visceral activities.
The brain stem relays and transmits signals from the brain.

Cerebrum

The cerebrum is involved in higher mental functions such as intelligence, speech, motivation, and judgment.
It has five major lobes (frontal, parietal, temporal, occipital, and insula.)
Different cortical areas associated with speech, sensation, motor, memory, and emotions are in each of these areas.
The different areas of consciousness are located in different sections of the cerebral cortex.

Diencephalon

The diencephalon is composed of the thalamus, hypothalamus, and epithalamus.
The thalamus is a sensory relay station that integrates information from different sensory neurons.

Brainstem

The brainstem is composed of the midbrain, pons, and medulla oblongata
The midbrain connects the cerebrum to the lower nervous system (including the spinal cord.)
The pons connects the cerebellum to the brain and is involved in breathing and other reflexes.
The medulla oblongata relays signals between the brain and spinal cord. It also carries out some reflexes and controls vital functions like breathing.

Cerebellum

The cerebellum coordinates voluntary movements.
It also monitors and maintains posture and balance.

Functional Brain Systems

Limbic system: involved in emotion and memory formation. Parts include the amygdala, rhinencephalon (olfactory bulb and tract), cingulate gyrus, and hippocampus.
Reticular formation: responsible for alertness and filters stimuli. It communicates with various brain structures to maintain alertness, control autonomic functions and regulate skeletal muscle activity.

Meninges

Meninges are three connective tissue membranes that cover and protect the CNS.
Pia mater is the innermost layer.
Arachnoid mater is the middle layer.
Dura mater is the outermost layer in the Meninges.

Cerebrospinal Fluid (CSF)

CSF is continuously produced in the brain's ventricles.
It fills the subarachnoid space in the brain and spinal cord, providing cushioning and protection.
CSF bathes the brain and spinal cord.

Blood Brain Barrier

Astrocytes induce tight junctions in the endothelial cells in brain capillaries.
This creates a very selective barrier between blood and nervous tissue.
The blood brain barrier protects brain neurons from harmful substances in the blood.
However, some materials can pass through the BBB in some regions.

Spinal Cord

The spinal cord is a major part of the CNS that extends from the medulla oblongata in the brainstem through the vertebral column to the lumbar vertebrae (approx.L1-L2 in humans).
Cervical and lumbar enlargements are present where nerves to the upper and lower limbs emerge.
The spinal cord finishes as the conus medullaris and is connected via a filum terminale.
The spinal cord has 31 spinal nerves.
The spinal cord contains ascending and descending tracts.
Gray matter within the spinal cord is organized into dorsal, ventral, and lateral horns.

Spinal Nerves

There are 31 pairs of spinal nerves that form a network of connections between the spinal cord and parts of the body.

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Description

Explore the fundamental components of the nervous system, including the central and peripheral systems, the types of neurons, and the role of glial cells. This quiz covers the structure and function of neurons, the process of action potentials, and the importance of myelin sheaths in nerve signal transmission.