Neuroscience Chapter on CNS Functions

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Questions and Answers

Which of the following is NOT a function of the cerebrospinal fluid (CSF)?

Nourishing the brain and transporting chemical signals

Protecting the CNS from blows and trauma

Providing buoyancy to the central nervous system (CNS) structures

Transporting oxygen to the heart (correct)

What is the primary mechanism that permits the passage of lipid-soluble substances through the blood brain barrier (BBB)?

Facilitated diffusion

Active transport

Endocytosis

Simple diffusion (correct)

Which of the following substances are typically prevented from entering the brain by the blood-brain barrier?

Proteins (correct)

Amino acids

Oxygen

Glucose

What is the significance of the blood brain barrier being absent in certain areas of the brain, such as the vomiting center?

To enable the vomiting center to detect harmful substances in the blood. (D) Signup and view all the answers

Which of the following cell types contribute to the formation of the blood brain barrier?

Astrocytes (D) Signup and view all the answers

What is the primary function of a synapse?

To facilitate the transfer of information between neurons using neurotransmitters. (C) Signup and view all the answers

Which of the following best describes the difference between a nerve and a tract?

A nerve is a bundle of axons in the peripheral nervous system, while a tract is a bundle of axons in the central nervous system. (D) Signup and view all the answers

What is neuroplasticity?

The ability of the brain to compensate for damage or disease by forming new connections. (A) Signup and view all the answers

What is the primary function of the meninges?

To protect the central nervous system, enclose blood vessels, and contain cerebrospinal fluid. (B) Signup and view all the answers

Which of the following layers of the meninges is the outermost and strongest?

Dura mater (B) Signup and view all the answers

Which of the following is NOT a characteristic of white matter in the brain?

It is found in the cerebral cortex. (B) Signup and view all the answers

What is the significance of the convolutions in the brain?

They increase the surface area of the brain, allowing for more neurons to develop. (B) Signup and view all the answers

What is the purpose of myelination in the nervous system?

To increase the speed of signal transmission along axons. (B) Signup and view all the answers

What is the main function of the primary motor area in the frontal lobe?

Controlling voluntary movements (B) Signup and view all the answers

Which of the following is NOT a function of the basal nuclei?

Regulate body temperature (D) Signup and view all the answers

What lobe is responsible for the conscious awareness of odors?

Temporal lobe (C) Signup and view all the answers

What is NOT a function of the parietal lobe?

Visual processing (C) Signup and view all the answers

Which brain structure is closely associated with the basal nuclei?

Thalamus (C) Signup and view all the answers

Which lobe is responsible for processing and giving meaning to what we hear?

Temporal lobe (D) Signup and view all the answers

Which of the following is a disorder of the basal nuclei?

Parkinson's disease (A) Signup and view all the answers

What is the role of Broca's area in the frontal lobe?

Producing speech (A) Signup and view all the answers

What is the main difference between short-term memory (STM) and long-term memory (LTM)?

STM has a limited capacity of 7-8 pieces of information, while LTM has a limitless capacity. (D) Signup and view all the answers

Which factor is NOT directly related to the transfer of information from short-term memory (STM) to long-term memory (LTM)?

Sleep duration (B) Signup and view all the answers

Which type of memory is responsible for remembering how to ride a bicycle?

Motor (B) Signup and view all the answers

Which of these is NOT a characteristic of REM sleep?

Increased muscle activity (A) Signup and view all the answers

Which part of the brain plays a key role in regulating sleep-wake cycles?

Hypothalamus (D) Signup and view all the answers

What is the primary function of the orexins released by the hypothalamus?

Helping the cortex to wake up (A) Signup and view all the answers

What is the primary difference between NREM and REM sleep?

NREM sleep is associated with decreased heart rate and blood pressure, while REM sleep is associated with increased heart rate and blood pressure. (B) Signup and view all the answers

What is the relationship between sleep duration and memory consolidation?

Proper sleep, including both NREM and REM stages, is crucial for memory consolidation. (A) Signup and view all the answers

Which of the following structures is responsible for regulating sleep-wake cycles?

Epithalamus (D) Signup and view all the answers

Which lobe of the brain is involved in processing and relaying information between the cerebral cortex and other parts of the nervous system?

Thalamus (B) Signup and view all the answers

Damage to the substantia nigra, located in the midbrain, can lead to which of the following diseases?

Parkinson's disease (A) Signup and view all the answers

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

Processing visual information (C) Signup and view all the answers

Which brain region is primarily responsible for conscious awareness of balance?

Insula (B) Signup and view all the answers

Which of the following brain regions is responsible for coordinating movement?

Cerebellum (C) Signup and view all the answers

Which of the following statements accurately describes the function of the Pons?

It is located between the midbrain and medulla oblongata and helps regulate breathing. (C) Signup and view all the answers

Which of the following statements is TRUE about the Cerebrum?

The Cerebrum is the largest part of the brain and is responsible for higher-order functions, such as thinking, language, and memory. (A) Signup and view all the answers

Which of the following structures plays a role in regulating heart rate and blood pressure?

Medulla Oblongata (A) Signup and view all the answers

Which of the following describes the function of the occipital lobe?

Processing visual information and giving meaning to what we see. (C) Signup and view all the answers

Which of the following brain structures is responsible for regulating hunger and satiety?

Hypothalamus (D) Signup and view all the answers

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

Controlling voluntary movements. (D) Signup and view all the answers

Which of the following statements accurately describes the primary visual area of the brain?

It is located in the occipital lobe and is responsible for processing visual information. (B) Signup and view all the answers

Which of the following is a major function of the cerebral peduncles which are located in the midbrain?

They form pillars that hold up the cerebrum and contain motor tracts. (B) Signup and view all the answers

Which of the following structures secretes melatonin and is involved in regulating sleep-wake cycles?

Pineal gland (B) Signup and view all the answers

Which part of the brain is responsible for the "fight or flight" response?

Midbrain (C) Signup and view all the answers

Which of the following arteries supplies the brainstem, cerebellum, and spinal cord?

Vertebral arteries (A) Signup and view all the answers

What is the name of the circle of arteries at the base of the brain?

Circle of Willis (D) Signup and view all the answers

What does the term 'ischemia' refer to?

Tissue death due to lack of blood supply (A) Signup and view all the answers

Which of the following is NOT a type of brain injury?

Hemiplegia (D) Signup and view all the answers

What is the main function of the Circle of Willis?

To provide an alternative route for blood flow in case of an artery blockage (A) Signup and view all the answers

Which of the following substances is an excitotoxin that can worsen the condition of a stroke?

Glutamate (B) Signup and view all the answers

What is the most common cause of a cerebrovascular accident (CVA)?

Blood clot blocking a cerebral artery (A) Signup and view all the answers

What does the term 'cerebral edema' refer to?

Swelling of the brain (A) Signup and view all the answers

Study Notes

Nervous System Functions

The nervous system utilizes electrochemical signals for communication between neurons.
The cell membrane creates resistance to the flow of current in these signals.
Action potentials (nerve impulses) move over longer distances.
Action potential generation depends on a resting membrane potential.

Types of Nervous Tissue

Ganglion: Cluster of cell bodies in the peripheral nervous system (PNS)
Nucleus: Cluster of cell bodies in the central nervous system (CNS)
Nerve: Bundle of axons in the PNS
Tract: Bundle of axons in the CNS
Gray matter: Unmyelinated axons, cell bodies, dendrites, axon terminals, and blood vessels
White matter: Myelinated axons and blood vessels

Axon's Functional Characteristics

Axons generate and transmit nerve impulses along the axolemma.
Neurotransmitters (chemical signals) are released into the extracellular space when the impulse arrives at the axon terminal.
These neurotransmitters send signals to excite or inhibit nearby neurons.

Nervous System Support Tissues (Neuroglia)

Astrocytes: Most abundant, support neurons, anchor neurons to capillaries for nutrients, and maintain the chemical environment around neurons.
Microglial cells: Important in immunity, help destroy microorganisms near neurons.
Ependymal cells: Circulate cerebrospinal fluid (CSF), cushioning the brain and spinal cord.
Oligodendrocytes: Produce myelin sheaths, insulating layers around nerve fibers in the CNS.
Satellite cells: Surround cell bodies in the PNS, similar to astrocytes.
Schwann cells: Surround nerve fibers in the PNS, forming myelin sheaths similar to oligodendrocytes; vital for regeneration of damaged peripheral nerves.

Blood-Brain Barrier

It helps maintain a stable environment for the brain.
Substances from blood must pass through continuous endothelium of capillary walls before entering neurons.
Tight junctions ensure substances pass through, not around endothelial cells.
Simple diffusion allows lipid-soluble substances to pass freely through cell membranes.
Specific transport mechanisms facilitate the movement of substances like glucose, amino acids, and ions crucial to the brain.
Basement membrane of endothelial cells contains enzymes that destroy chemicals that could activate brain neurons.

Nervous System Divisions

Central Nervous System (CNS): Includes the brain and spinal cord; integrative and control centers.
Peripheral Nervous System (PNS): Includes cranial and spinal nerves; communication lines between the CNS and the rest of the body.
- Sensory (afferent) Division: Conducts impulses from receptors to the CNS.
  - Somatic and visceral nerve fibers.
- Motor (efferent) Division: Conducts impulses from the CNS to effectors (muscles and glands).
  - Somatic nervous system (voluntary).
  - Autonomic nervous system (involuntary).
    - Sympathetic division.
    - Parasympathetic division.

Efferent vs Afferent Division of the PNS

Efferent (Motor): Signals from the CNS to effector organs.
- Somatic (voluntary): Carries impulses to skeletal muscles.
- Autonomic (involuntary): Regulates activity of smooth , cardiac muscles, and glands.
Afferent (Sensory): Signals to the CNS from sensory organs.
- Somatic: Sensory fibers from the skin, muscles, joints.
- Visceral: Sensory fibers from internal organs.

Myelin Sheath Importance

Whitish, fatty (protein-lipoid segmented cover on nerve fibers.
Protects and electrically insulates nerve fibers
Increases speed of nerve impulses (action potentials).
Myelinated fibers conduct impulses faster than non-myelinated fibers.

Multiple Sclerosis

Autoimmune disorder, demmyelinating of CNS.
The immune system attacks the myelin surrounding nerve fibers.
Hardened patches (sclerosis) in the brain and spinal cord.
Disrupts communication between CNS and the rest of the body.

Membrane Potentials

Neurons communicate through electrochemical signals.
Cell membrane resistance impacts current flow.
Action potentials—electrochemical signals over long distances.
Action potentials depend on resting membrane potential.

Action Potentials

Dendritic nerve endings trigger the opening of gated ion channels, allowing ion flow across the plasma membrane.
If the inside of the plasma membrane becomes more positive than the resting membrane potential, an action potential is triggered (depolarization).
If the inside does not reach threshold, no action potential occurs.
Action potentials propagate along the axon.
At the axon terminal, action potentials cross to neighboring neurons via a synapse.

Stages of Action Potential Crossing a Synapse

Action Potential (AP) arrives at the axon terminal.
Calcium channels open, releasing calcium into the terminal.
Neurotransmitters (e.g., acetylcholine) are released.
Formation of a postsynaptic potential.
Action potential at the postsynaptic neuron.

Synapse

A chemical synapse is a specialized junction that mediates the transfer of information between neurons or neurons and effector cells.
Action potentials arriving at the axon terminal stimulate voltage-gated calcium channels to open.
Calcium influx causes synaptic vesicles to release neurotransmitters.
Neurotransmitters diffuse across the synaptic cleft & bind to receptors on the postsynaptic membrane.
Binding of neurotransmitters opens ion channels.

Nerve vs. Tract

Nerve: Bundle of axons in the PNS
Tract: Bundle of axons in the CNS

White Matter vs Gray Matter

White matter consists mainly of myelinated axons, some are nonmyelinated, while gray matter consists of mostly non-myelinated neurons, including those located in the cerebral cortex.

Neuroplasticity

The brain compensates for damage or disease by allowing nerve cells to form new connections.

Meninges

Tissues that cover and protect the central nervous system (CNS).
Protection for blood vessels.
Contain CSF.
Form partitions in the skull.
Consists of three layers: dura mater (strongest), arachnoid mater (middle), and pia mater (innermost).

Cerebrospinal Fluid (CSF)

Fluid that cushions the brain and spinal cord.
Constant volume.
Provides buoyancy to CNS structures.
Protects brain from blows and trauma.

Blood Brain Barrier

Helps maintain a stable environment for the brain.
Protects brain from toxins and harmful substances in the blood.
Substances from blood must pass through the continuous endothelium of capillary walls before gaining entry into neurons.
Tight junctions between endothelial cells and astrocytes control what passes through.

Blood Supply to Brain

Brain is supplied by two internal carotid arteries and two vertebral arteries.
Deep artery supplies brain, eyes and nose
Branches: ophthalmic and anterior cerebral, middle cerebral
Ascends through the neck, enters skull, branches to supply different parts of the brain.
Circle of Willis: A circle of interconnected arteries at the base of the brain; if one artery is blocked, other arteries can compensate to maintain blood flow to the brain.

Clinical Application: Traumatic Brain Injuries

Brain injuries include concussion (temporary alteration in function), contusion (permanent damage), and subdural or subarachnoid hemorrhage.
Cerebral edema swelling of the brain associated with head injuries.

Clinical Application: Cerebrovascular Accidents (CVAs)

Also known as "strokes."
Third leading cause of death in North America.
Ischemia (tissue deprived of blood supply.)
Caused by blockage of cerebral artery.
Glutamate can worsen condition acting as a excitotoxin.
Hemiplegia, sensory or speech deficits may result.

Cerebrum Areas

Involved in cognition and emotion, regulating slow movement, filtering out unnecessary movement.

Major Landmarks: Fissures

Longitudinal fissure, separates cerebral hemispheres.
Transverse fissure, separates cerebrum from cerebellum.

Hemispheres and Communication

Left and right hemispheres are divided by the longitudinal fissure.
Communicate through the corpus callosum.

Cerebral White Matter

Responsible for communication between cerebral areas and lower CNS.
Consists of myelinated fibers bundled into tracts.
Classified according to direction: association, commissural, and projection fibers.
Function: Communication and relay station, facilitating higher-level functions.

Premotor Cortex

Located in the frontal lobe; important in planning and staging of movement
Staging for skilled movements, repetitive or patterned motor skills.
Coordination of simultaneous or sequential movements.

What if Premotor Cortex is Injured?

Loss of control over movements, but not strength.
Difficulty using sensory feedback.

Basal Nuclei

Cognition and emotion.
Regulates intensity of slow movement.
Filters out incorrect responses, and inhibits unnecessary movement.
Associated with the subthalamic nuclei (diencephalon) and substantia nigra (midbrain).

Cerebrum Lobes

Frontal, parietal, temporal and occipital and insula.

Frontal Lobe Functions

Primary motor area, for movement (including planning).
Motor association areas.
Primary olfactory cortex (smell), Broca's area (speech).
Cognitive thought & voluntary movement.

Temporal Lobe Functions

Primary auditory area processing hearing
Auditory association – recognizing sounds
Wernicke's area—comprehension
Special senses (hearing, smelling)
Learning, and memory retrieval
Emotions
Processes sounds, smell, and language comprehension (Wernicke's area).

Parietal Lobe Functions

Primary somatosensory area (cortex) – sensory input from the body
General sensory association areas— processing and understanding sensations, relating them to previous memories.

Occipital Lobe Functions

Primary visual area (cortex) – processing visual information
Visual association areas— recognition of visual information relating it to past memories. Involved in visual memory.

Insula Function

Special senses (taste, hearing)
Vestibular and visceral sensations
Consciousness of balance and position of the head in space

Sensory Homunculus

A diagram representing the amount of cortical space assigned to different body parts involved in sense.

Motor Homunculus

Diagram showing the amount of cortical space assigned to different body parts involved in motor control

Diencephalon

Located between the brainstem and cerebrum.
Consists of three paired gray matter structures (thalamus, hypothalamus, and epithalamus)
Involved in relaying sensory information, regulating emotions, and controlling the endocrine system.

Thalamus

Relay station for sensory information to the cerebral cortex.
Processes and relays sensory information to cerebral cortex.
Involved in controlling emotions. (part of limbic system).
Important for receiving motor output from cerebellum to the cerebral cortex.

Hypothalamus

Homeostasis regulation
Body temperature control (sweating, shivering).
Hunger, satiety, and thirst regulation.
Sleep-wake cycles regulation.
Controls autonomic nervous system and endocrine functions.

Epithalamus

Contains the pineal gland, which secretes melatonin (regulates sleep-wake cycle).
Involved in emotional responses to odors

Brain Stem

Made up of midbrain, pons, and medulla oblongata.
Controls automatic behaviors.
Contains tracts connecting higher and lower neural centers.
Connected to 10 of the 12 cranial nerves.

Midbrain

Smallest part of the brain stem.
Important for sensory and motor integration
Cerebral peduncles (bundles of nerve fibers that carry motor impulses from the brain).
Substantia nigra (involved in motor control).
Visual and auditory responses, coordination, movement, and the "fight or flight" response

Pons

Relay station for sensory information.
Conduction tracts connecting cerebrum and cerebellum.
Origin of cranial nerves V (trigeminal), VI (abducens), VII (facial).
Motor control and coordination

Medulla Oblongata

Cardiac, respiratory, and vasomotor functions.
Autonomic reflexes (heart rate, breathing, blood pressure).
Cranial nerves IX (glossopharyngeal), X (vagus), XI (accessory), XII (hypoglossal) originate here.
A transition area to connect brain to spinal cord

Cerebellum

Posterior part of the brain.
Muscle coordination, balance, fine-tuning of movements, at conscious and subconscious levels.
Essential for motor coordination and skilled movements; important for posture and balance; involved in learning of new motor skills.
Receives input from the cerebral cortex and sensory receptors.
Sends signals to the cerebral cortex to coordinate movements.

Reticular Formation

Sends impulses to cerebral cortex to maintain consciousness—essential in arousal.
Filters out background stimuli from consciousness (keeps CNS alert and responsive to important stimuli).
Involved in motor control and arousal / sleep regulation.

Language

Language relies on a network of areas in the left hemisphere.
Broca's area (speech production): Patients with lesions here can understand words but cannot speak.
Wernicke's area (comprehension): Involved in understanding spoken and written words; patients with lesions here can speak but words lack meaning.

Memory

Different types include declarative (facts and events), procedural (skills), and emotional (experiences linked to emotions).
Short-term memories can become long-term memories through emotional arousal, rehearsal techniques, and associating information with existing knowledge.

Sleep and Sleep-Wake Cycles

Sleep is a state of partial unconsciousness.
Brain stem activity remains active during sleep.
Non-rapid eye movement (NREM) and rapid eye movement (REM) sleep.
Different stages of NREM sleep vary in depth/level of consciousness.
REM sleep associated with dreaming and active brain activity, with limited skeletal muscle activity.

How is Sleep Regulated?

Circadian rhythm.
Hypothalamus plays a major role in regulating sleep, particularly the biological clock.
Reticular activating system, releases chemicals that either increase or decrease consciousness (orexin).

Parkinson's Disease Pathophysiology

Degeneration of dopamine neurons in the substantia nigra.
Dopamine deficiency hinders signals from the substantia nigra to the corpus striatum.
This loss disrupts coordination, leading to tremors, rigidity, slowness of movement, and balance/coordination issues.

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Description

Test your knowledge of the central nervous system with this quiz covering cerebrospinal fluid, the blood-brain barrier, synapse functions, and neuroplasticity. Explore key concepts, including the roles of meninges and white matter, and the significance of brain convolutions and myelination.