HSCI Chapter 6

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Questions and Answers

What role does the presynaptic neuron play in neurotransmission?

It receives signals from the postsynaptic neuron.

It facilitates the reuptake of neurotransmitters.

It generates action potentials in the postsynaptic neuron.

It releases neurotransmitters into the synaptic cleft. (correct)

What terminates the activity of a neurotransmitter at a synapse?

Continuous release of neurotransmitters.

Breakdown by enzymes or reuptake by the presynaptic neuron. (correct)

Binding to the presynaptic membrane.

Increased action potential frequency.

Which of the following is true regarding the action of neurotransmitters?

They bind to receptors and trigger a response in the postsynaptic neuron. (correct)

They are stored in the synaptic cleft until needed.

They create action potentials in the presynaptic neuron.

They can only inhibit neuronal activity.

Which component of the central nervous system provides cushioning for the brain and spinal cord?

Cerebrospinal fluid Signup and view all the answers

What is the primary effect of serotonin in the brain?

Determining mood and emotional state. Signup and view all the answers

What is the first step in the nerve impulse transmission process?

Stimulus activates receptor Signup and view all the answers

Which part of the nervous system is primarily responsible for involuntary control over heart rate?

Sympathetic nervous system Signup and view all the answers

Which component of the reflex arc directly carries nerve impulses from sensory neurons to the central nervous system?

Spinal cord Signup and view all the answers

What is the role of efferent nerves in the nervous system?

Transmit signals from CNS to muscles Signup and view all the answers

How does the sympathetic nervous system achieve efficiency in responding to stimuli?

By branching a single spinal nerve to multiple organs Signup and view all the answers

What is a primary function of the parasympathetic nervous system?

To maintain homeostasis and body systems at rest Signup and view all the answers

What structure serves as the gap between neurons where neurotransmitters are released?

Synapse Signup and view all the answers

In the nerve impulse transmission pathway, which structure is responsible for receiving the impulse after it crosses the synapse?

Dendrite of the next neuron Signup and view all the answers

What happens at the synapse during nerve impulse transmission?

Chemical signals are sent across the synapse Signup and view all the answers

Which component is essential for increasing the speed of impulse travel along the axon?

Myelin sheaths Signup and view all the answers

In a two-neuron reflex arc, what types of neurons are involved?

Sensory and motor neuron Signup and view all the answers

What defines the phase of depolarization in a neuron?

Na+ ions influx creating a positive charge inside Signup and view all the answers

What primarily causes the change in membrane potential during an action potential?

The influx of Na+ ions Signup and view all the answers

What role do Nodes of Ranvier play in nerve impulse conduction?

They facilitate ion flow along the axon Signup and view all the answers

In a three-neuron reflex arc, which additional component is included besides the sensory and motor neurons?

Interneuron Signup and view all the answers

What triggers the next segment of a neuron to depolarize?

The entry of Na+ ions into the previous segment Signup and view all the answers

Study Notes

Synapse

A synapse is a point where "electrical" information is converted to "chemical" information
Occurs at the end of dendrites and axons
It is the junction between two neurons or a neuron and another cell

Synapse Components

Presynaptic neuron: Neuron sending the signal
Postsynaptic neuron: Neuron receiving the signal
Neurotransmitter: Chemical messenger released from the presynaptic neuron
Synaptic vesicle: Small sac containing neurotransmitters
Synaptic cleft: Gap between the presynaptic and postsynaptic neurons

Neurotransmitters

Chemicals released from presynaptic axons
Bind to receptors on the postsynaptic membrane triggering an action potential in the receiving neuron
Activity is terminated by breakdown (enzymes) or reuptake (presynaptic neuron)
Over 30 different neurotransmitters have been identified

Neurotransmitter Imbalances: Antidepressants

Serotonin is a neurotransmitter related to mood
Depression is thought to be linked to a decrease in serotonin levels

Central Nervous System

Composed of the brain and spinal cord

Protection of the Central Nervous System (CNS)

Bone: Skull protects the brain, vertebral column protects the spinal cord
Membranes (meninges): Dura mater, pia mater, and arachnoid mater surround the brain and spinal cord
Cerebrospinal fluid: Fills the meninges, circulates between ventricles and the blood

Nerve Impulses

Action potential: Propagation of a charge differential down the axon
Myelin sheaths increase the speed of action potential travel
Depolarization: Shift in the charge of a neuron from negative to positive
Ion flow occurs at the Nodes of Ranvier

Nerves and Synapses

Carry information between the central nervous system (CNS) and peripheral nervous system (PNS)
Nerve impulse transmission: Stimulus --> dendrite --> cell body --> axon --> synapse --> dendrite --> cell body --> axon --> synapse --> muscle

Reflex Arc and Action Potential

Afferent nerves carry impulses from sensory stimuli to the CNS
Efferent nerves carry impulses from the CNS to motor neurons, leading to movement

Autonomic Nervous System (Involuntary)

Responsible for controlling involuntary functions
Controls cardiac muscle tissue, smooth muscle tissue, and glandular epithelial tissue
Divided into sympathetic and parasympathetic divisions

Sympathetic Nervous System (SNS)

Prepares the body for stress (threat, injury)
Increases heart rate and muscle contraction
Controlled by spinal nerves
One spinal nerve can activate several secondary branches, maximizing efficiency

Parasympathetic Nervous System (PNS)

Maintains homeostasis
Slows down bodily functions - decreases heart rate, relaxes muscles
Controlled by cranial nerves
Important for regulating breathing, digestion, and other involuntary functions

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Description

Explore the intricate world of synapses and neurotransmitters in this quiz. Learn about the components of a synapse, including the roles of presynaptic and postsynaptic neurons, and the importance of neurotransmitters in neural communication. Understand how imbalances in these chemicals can affect mood and may lead to conditions like depression.