Physiology of CNS and PNS Quiz

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Questions and Answers

What is primarily influenced by the number of receptors in the sensory area of the cerebral cortex?

Emotional responses

Memory formation

Intensity of stimuli (correct)

Motor coordination

Which type of signal is NOT directly associated with the efferent system from the sensory areas of the cerebral cortex?

Sensory feedback signals (correct)

Endocrine signals

Visceral responses

Somatic motor signals

What characteristic of an axon allows for the acceleration of electrical impulses?

Presence of myelin sheath (correct)

Diameter of the soma

Number of dendrites

Length of the neuron

What is formed by the Schwann cells that wrap around the axon?

Myelin sheath Signup and view all the answers

What is the role of the nodes of Ranvier in neuronal function?

To facilitate faster impulse transmission Signup and view all the answers

What distinguishes between the roles of neurons and neuroglia in the nervous system?

Neurons conduct electrical signals; neuroglia provide support. Signup and view all the answers

Which part of the neuron is primarily involved in transmitting impulses away from the cell body?

Axon Signup and view all the answers

What primarily determines whether a signal transmitted by a neuron is long or short in duration?

The length of the axon Signup and view all the answers

Which region of the gray matter is involved in higher brain functions?

Cerebral cortex Signup and view all the answers

Which of the following structures is NOT part of the brain stem?

Cerebellum Signup and view all the answers

What is the primary function of the neurons categorized as afferent?

Transmit sensory information to the spinal cord Signup and view all the answers

Which component is responsible for the coordination of movement?

Cerebellum Signup and view all the answers

What is the function of the corpus callosum?

Connect the left and right hemisphere of the brain Signup and view all the answers

Which part of the central nervous system is primarily responsible for integrating reflex actions?

Spinal cord Signup and view all the answers

The structures of the white matter primarily consist of what?

Myelinated axons Signup and view all the answers

Which statement about the diencephalon is correct?

It serves as a relay center for sensory information. Signup and view all the answers

What is the role of neurotransmitters in synaptic transmission?

They bind to receptors, influencing ion channels or G-proteins. Signup and view all the answers

Which synaptic potential is associated with ion channel binding?

Fast synaptic potential Signup and view all the answers

What kind of signal is characterized by faster conduction in synapses?

Electrical signal Signup and view all the answers

What is the primary function of the axon hillock?

To generate electrical signals that determine action potential. Signup and view all the answers

What type of signaling involves neurocrines?

Chemical signaling from presynaptic to postsynaptic neurons. Signup and view all the answers

Which of the following is NOT a condition of neuron states?

Depolarized Neuron Signup and view all the answers

How does slow synaptic potential occur?

By the binding of neurotransmitters to G-proteins. Signup and view all the answers

Which statement correctly describes the function of chemical signals in the synapse?

They require a wider space for effective transmission within the nervous system. Signup and view all the answers

What characterizes the preganglionic neurons in the sympathetic system?

Short and located in the thoracic and lumbar regions Signup and view all the answers

Which of the following statements about somatic motor pathways is true?

They consist of a single neuron from the CNS to skeletal muscle. Signup and view all the answers

What is the role of Schwann cells at the neuromuscular junction?

They form a thin layer around the axon terminals to accelerate action potentials. Signup and view all the answers

During the process of synaptic transmission at the neuromuscular junction, what occurs first when an action potential reaches the axon terminal?

Acetylcholine is released into the synaptic cleft. Signup and view all the answers

What type of receptors are primarily found in the neuromuscular junction that respond to acetylcholine?

Nicotinic cholinergic receptors Signup and view all the answers

What distinguishes the autonomic nervous system from the somatic system in terms of neuron behavior?

Autonomic pathways can be either excitatory or inhibitory. Signup and view all the answers

In which part of the nervous system are the cell bodies of preganglionic neurons located in the parasympathetic division?

Sacral region and brainstem Signup and view all the answers

What function does the NMJ (neuromuscular junction) serve?

To transmit signals from motor neurons to skeletal muscles Signup and view all the answers

What happens to neurotransmitters after they have fulfilled their role in neurotransmission?

They can diffuse out of the synapse or be inactivated by enzymes. Signup and view all the answers

What characterizes the resting membrane potential of a neuron at rest?

The resting membrane potential is typically -65 mV. Signup and view all the answers

What initiates an action potential in a neuron?

Depolarization reaching a certain threshold. Signup and view all the answers

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

It increases sodium permeability allowing influx. Signup and view all the answers

What occurs during the repolarization phase of an action potential?

Potassium ions exit the neuron, returning it to a negative state. Signup and view all the answers

In an inhibited state, which ions primarily influence the membrane potential of a neuron?

Chloride ions and potassium ions. Signup and view all the answers

What defines the term Inhibitory Post Synaptic Potential (IPSP)?

Hyperpolarization caused by increased chloride influx. Signup and view all the answers

What factor(s) affect the resting membrane potential of a neuron?

Permeability to potassium ions and additional membrane conditions. Signup and view all the answers

Study Notes

Physiology of the Central Nervous System (CNS) and Peripheral Nervous System (PNS)

Neurons transmit electrical impulses, initiating responses via neurotransmitters and neuromodulators.
Constituents of the brain include gray and white matter:
- Gray Matter: Comprises the cerebral cortex, basal ganglia, and limbic system.
- White Matter: Responsible for neural communication between regions.

Brain Structure and Function

The brain consists of six major divisions:
- Cerebrum: Responsible for higher brain functions.
- Diencephalon: Acts as a central relay for sensory information.
- Midbrain: Involved in vision, hearing, motor control, and sleep/wake.
- Cerebellum: Coordinates movement and balance.
- Pons: Connects different parts of the brain and aids in regulating functions such as breathing.
- Medulla Oblongata: Regulates vital autonomic functions like heart rate and breathing.

Spinal Cord and Reflexes

The spinal cord integrates sensory information and coordinates reflex responses before sending data to the brain.
Reflex actions occur rapidly without direct involvement of the brain, enhancing response times.

Peripheral Nervous System (PNS) Divisions

The PNS includes:
- Afferent Neurons: Relay sensory information from receptors throughout the body to the central nervous system (CNS).
- Efferent Neurons: Carry signals away from the CNS to effectors (muscles and glands).
  - Somatic Motor Pathway: Controls skeletal muscles, providing excitatory signals.
  - Autonomic Nervous System: Involves both sympathetic and parasympathetic divisions.

Sympathetic and Parasympathetic Nervous System

Sympathetic Nervous System:
- Originates from thoracic and lumbar regions.
- Features short preganglionic neurons and long postganglionic neurons; prepares the body for "fight or flight."
Parasympathetic Nervous System:
- Emerges from cranial and sacral regions.
- Long preganglionic neurons and short postganglionic neurons; promotes "rest and digest" activities.

Neuron Structure and Function

Neurons are the functional units for carrying electric signals; neuroglia provide support.
Axon Morphology:
- Axons covered in myelin sheath by Schwann cells, enhancing the speed of nerve impulses.
- Notable feature includes Nodes of Ranvier, which facilitate faster conduction through saltatory conduction.

Neuromuscular Junction (NMJ)

NMJ connects motor neurons to skeletal muscles; critical for muscle contraction.
- Components of NMJ include axon terminals, synaptic clefts, and postsynaptic muscle membranes.
- Neuron action potential leads to calcium influx, triggering vesicle release of acetylcholine (ACh).

Signal Transmission and Neurotransmitter Dynamics

Neurotransmitter actions:
- ACh binds to nicotinic receptors on skeletal muscle, inducing muscle activation.
- Neurotransmitter effects may be excitatory or inhibitory, influencing post-synaptic potentials (EPSP or IPSP).
Resting Membrane Potential:
- Neurons at rest exhibit a potential of approximately -65 mV, influenced by ion permeability, particularly sodium and potassium.
- Initiation of action potential occurs upon depolarization when threshold is achieved.

Neurotransmitter Recycling and Termination

Following neurotransmission, mechanisms include:
- Reuptake into axon terminals.
- Enzymatic degradation.
- Diffusion away from synaptic cleft.

Excitation and Inhibition

Action potentials are characterized by phases of depolarization followed by repolarization.
IPSPs are triggered by chloride influx and potassium efflux, leading to hyperpolarization.

Summary of Neurophysiological States

Neurons can exhibit three states:
- Resting: Stable negative charge; ready to transmit signals.
- Excited: Increased permeability allows action potentials.
- Inhibited: Hyperpolarized state, reducing likelihood of action potentials.

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Description

Test your knowledge on the physiology of the central and peripheral nervous systems. This quiz covers neuron functions, brain structure, and the role of different brain regions. Challenge yourself with questions on reflexes and neural communication!