Neurobiology Quiz: Neurons and Reflexes

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Questions and Answers

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

Interneurons

Afferent neurons (correct)

Autonomic neurons

Efferent neurons

In which anatomical division do interneurons reside?

Peripheral nervous system

Central nervous system (correct)

Efferent division

Somatic nervous system

Which of the following describes the function of efferent neurons?

Process sensory information in the CNS

Transmit information from muscles to the CNS

Carry motor information from the CNS to effector structures (correct)

Innervate smooth muscle only

How many pairs of cranial nerves are part of the peripheral nervous system?

12 pairs Signup and view all the answers

What type of neurons have cell bodies located in the CNS and extend their axons to the periphery?

Efferent neurons Signup and view all the answers

Which division of the peripheral nervous system primarily innervates skeletal muscles?

Somatic nervous system Signup and view all the answers

What percentage of neurons in the human body do interneurons account for?

99% Signup and view all the answers

Which type of neuron activates a particular type of sensory receptor?

Afferent neurons Signup and view all the answers

What is the role of the spinal cord in the nervous system?

Transmit motor commands from the CNS to the PNS Signup and view all the answers

Which of the following functions is primarily handled by the spinal cord during reflex actions?

Integration of sensory input Signup and view all the answers

Which structure of the brainstem is NOT involved in basic life-sustaining processes?

Cerebrum Signup and view all the answers

What type of reflex involves comparatively few interneurons and does not require input from higher nervous centers?

Withdrawal reflexes Signup and view all the answers

Which neurons are responsible for carrying stimuli from the body to the spinal cord?

Afferent neurons Signup and view all the answers

Which part of the CNS primarily processes motor activities in the head, neck, and face?

Brainstem Signup and view all the answers

Which of the following responses is characterized by complexity and may involve millions of interneurons?

Higher cognitive functions Signup and view all the answers

Which of the following is a function of interneurons?

Connecting afferent and efferent neurons Signup and view all the answers

What is the primary role of the cerebral cortex in the central nervous system (CNS)?

Controlling voluntary movements and complex cognitive functions Signup and view all the answers

Which statement accurately describes the composition of the cerebrum?

It contains both gray matter on the outer surface and white matter underneath. Signup and view all the answers

How is the total surface area of the cerebral cortex significant in different species?

It increases in larger species, allowing for more complex functions. Signup and view all the answers

What is the term used for bundled axons in the central nervous system (CNS)?

Tracts Signup and view all the answers

What anatomical feature is primarily responsible for increasing the surface area of the cerebral cortex?

Gyri Signup and view all the answers

Which of the following is NOT a function of the cerebrum?

Regulation of heart rate Signup and view all the answers

What type of tissue is primarily located on the outer surface of the cerebrum?

Gray matter Signup and view all the answers

Which statement about the ventricles of the brain is true?

They are filled with cerebrospinal fluid (CSF). Signup and view all the answers

What is the primary function of the thalamus in relation to sensory information?

It acts as a relay station for sensory information. Signup and view all the answers

Which of the following structures is primarily involved in the control of voluntary movement?

Basal ganglia Signup and view all the answers

How does the thalamus filter sensory information?

By selectively allowing important information to pass. Signup and view all the answers

What is the composition of the basal ganglia?

Gray matter embedded in white matter. Signup and view all the answers

What role does the thalamus play in muscle contraction regulation?

It reinforces voluntary motor activity initiated by the cortex. Signup and view all the answers

Which lobe of the cerebral cortex is responsible for higher-level cognitive functions?

Frontal lobe Signup and view all the answers

Which is NOT a characteristic of the cerebral cortex?

It has a smooth surface. Signup and view all the answers

What percentage of sensory information is typically discarded by the thalamus as irrelevant?

99% Signup and view all the answers

Signup and view all the answers

Study Notes

Physiology & Pathophysiology MD 303

This is a Level 2 clinical pharmacy program
The nervous system is made up of billions of interconnected neurons in a highly organized circuit.
The nervous system is divided into two major anatomically distinct regions: Central Nervous System (CNS) and Peripheral Nervous System (PNS).
CNS includes the brain and spinal cord
PNS includes 12 pairs of cranial nerves arising from the brainstem and 31 pairs of spinal nerves arising from the spinal cord.

The Nervous System

Cranial nerves: Olfactory (smell), Optic (vision), Oculomotor (eye movement, pupil reflex), Trochlear (eye movement), Abducens (eye movement), Trigeminal (face sensation, chewing), Facial (face movement, taste), Vestibulocochlear (hearing, balance), Glossopharyngeal (throat sensation, taste, swallowing), Vagus (movement, sensation, abdominal organs), Accessory (neck movement), Hypoglossal (tongue movement).
Each nerve has a specific function.

Spinal Cord

The spinal cord is the most inferior portion of the CNS.
It receives sensory input from the peripheral body and contains the cell bodies of motor neurons for voluntary and involuntary movements.
The spinal cord processes sensory and motor activities in the trunk and limbs.
Involuntary and simple reflexes are processed at the spinal cord level.
Voluntary movements are initiated and controlled by thought processes in the cerebrum.

Levels of CNS Function

The spinal cord processes reflexes and transmits nerve impulses to and from the brain, receives sensory input, and initiates motor output. It also controls life-sustaining processes.
The Brain stem (consisting of medulla, pons, and midbrain) receives sensory input, initiates motor output, and is continuous with the spinal cord, controls subconscious, involuntary functions like cardiovascular activity, respiration, swallowing, and vomiting.
The brainstem is a relay station for information transfer between the cerebrum and cerebellum, also aids in breathing. The midbrain controls eye movement, auditory, and visual reflexes.
The cerebrum and cerebral cortex are responsible for processing, integrating, and analyzing information, involved with cognition, voluntary movement, sensory perception, and language.
The cerebrum accounts for 80% of the total brain weight
Voluntary movements are initiated in the cerebrum
Convolutions increase surface area for more neurons
The cerebral cortex processes information for intellect, thoughts, personality, sensory perception, voluntary movement initiation.

The Brain

The brain is the integrative portion of the nervous system for receiving, processing, storing sensory information, and orchestrating motor response.
The brain is divided into several distinct regions.
The forebrain consists of the cerebrum, basal ganglia, thalamus, hypothalamus.
Midbrain is part of the brainstem
Hindbrain consists of pons, medulla, and cerebellum.

The Cerebrum

The cerebrum is composed of two hemispheres.
The hemispheres are connected to allow communication
Gray matter (unmyelinated cell bodies) forms the cerebral cortex on the outer surface.
White matter (myelinated axons) is within the core.
Axons are bundled into tracts by function.

Nerves versus Tracts

Nerves are bundles of axons found in the PNS only.
Tracts are bundles of axons found in the CNS only.

Frontal Section of the Brain

The cerebrum is made of white matter internally and gray matter externally forming the cerebral cortex.
Basal ganglia and the thalamus are embedded within the cerebral hemispheres.
The ventricles are filled with cerebrospinal fluid (CSF).

The Cerebral Cortex

The cerebral cortex is folded, not smooth, increasing neuron space
It's divided into four lobes: frontal, temporal, parietal, and occipital. Each lobe has a specific processing function.

The Basal Ganglia

Masses of gray matter embedded in the white matter of each cerebral hemisphere.
They contribute to voluntary movement control.

The Thalamus

Located between the cerebrum and brainstem.
Acts as a relay station for sensory input to the cerebral cortex (except olfactory).
Acts as a filter for the cerebral cortex
Involves the regulation of skeletal muscle contraction by positively reinforcing voluntary motor activity.

The Hypothalamus

Lies beneath the thalamus.
It plays a vital role in homeostasis.
Its functions include regulating the autonomic nervous system, endocrine system, temperature, plasma volume, thirst, hunger, urine output, behavior, and emotions.

The Brainstem

Consists of midbrain, pons, and medulla of the hindbrain.
Contains control centers for subconscious, involuntary functions (cardiovascular, respiration, and swallowing)
It acts as a relay station for information transfer between the cerebrum and cerebellum.
It also plays a vital role in breathing, auditory, and visual reflexes.

The Reticular Formation

A diffuse network of neurons in the brainstem.
It plays key roles in cortical alertness, attention, sleep, emotional facial expressions, eating, breathing, and pain response.

The Cerebellum

Part of the hindbrain
Accounts for >50% of all brain neurons
Important role in coordinating movement and maintaining balance and equilibrium.
Plays a role when movements are in progress and during repetitions.

Cerebrospinal Fluid (CSF)

Derived from the choroid plexus
CSF composition differs from plasma composition.
The CSF maintains a consistent chemical environment for neurons, which optimizes function.
Serves as a protective shock absorber.
Constant turnover facilitates removal of harmful metabolites

The Spinal Cord

Lowest level of the CNS.
Divided into cervical, thoracic, lumbar, sacral, and coccygeal regions, each subdivided into functional segments.
A pair of spinal nerves extend from each segment.

Functional Types of Neurons in the Spinal Cord

Second-order sensory neurons (dorsal horn): receive input from afferent neurons.
Visceral motor neurons (lateral horn): related to the autonomic nervous system (ANS).
Somatic motor neurons (ventral horn): innervate skeletal muscles.
Interneurons (throughout gray matter): small, unmyelinated, receive input from higher CNS levels and sensory neurons to perform integrative functions like reflexes.

Spinal Reflexes

Reflexes are categorized based on the effector (skeletal muscle, smooth muscle, glands) and region of the CNS processing the reflex (cranial or spinal).
Simple (preprogrammed) reflexes, and acquired (learned) reflexes
Reflex arcs involve sensory receptors, afferent neurons, integrating centers in the spinal cord, efferent neurons, and effector tissues which produce a reflex response.
Monosynaptic vs. polysynaptic reflexes

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Description

Test your knowledge on the types of neurons, their functions, and the role of the spinal cord in reflex actions. This quiz covers essential concepts related to the nervous system and its anatomical divisions. Understand how sensory information is processed and transmitted within the human body.