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Questions and Answers
What does functional magnetic resonance imaging (fMRI) primarily measure?
What does functional magnetic resonance imaging (fMRI) primarily measure?
Which part of the spinal cord is responsible for integrating reflex activity without involving the brain?
Which part of the spinal cord is responsible for integrating reflex activity without involving the brain?
What distinguishes a nerve from a neuron?
What distinguishes a nerve from a neuron?
How many pairs of spinal nerves emerge from the spinal cord?
How many pairs of spinal nerves emerge from the spinal cord?
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What is the function of afferent fibers in the spinal cord?
What is the function of afferent fibers in the spinal cord?
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Which part of the nervous system is responsible for voluntary actions?
Which part of the nervous system is responsible for voluntary actions?
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What is primarily formed by astrocytes in the nervous system?
What is primarily formed by astrocytes in the nervous system?
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Which of the following is a characteristic of white matter in the brain?
Which of the following is a characteristic of white matter in the brain?
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What is the function of the cerebrospinal fluid (CSF)?
What is the function of the cerebrospinal fluid (CSF)?
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Which neurons are classified as pseudounipolar?
Which neurons are classified as pseudounipolar?
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Which lobe of the brain is primarily responsible for decision-making functions?
Which lobe of the brain is primarily responsible for decision-making functions?
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What type of glial cell is involved in myelination in the central nervous system?
What type of glial cell is involved in myelination in the central nervous system?
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The basal nuclei are primarily associated with which function?
The basal nuclei are primarily associated with which function?
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Which area of the cerebral cortex is important for language comprehension?
Which area of the cerebral cortex is important for language comprehension?
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What structure connects the left and right hemispheres of the brain?
What structure connects the left and right hemispheres of the brain?
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Which of the following correctly describes the sequence of material exchange at the blood-brain barrier?
Which of the following correctly describes the sequence of material exchange at the blood-brain barrier?
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Which component of the CNS is primarily filled with cerebrospinal fluid?
Which component of the CNS is primarily filled with cerebrospinal fluid?
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Which type of neurons carry impulses away from the central nervous system?
Which type of neurons carry impulses away from the central nervous system?
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Study Notes
Nervous System I - Structure
- The nervous system is comprised of three major components: central, peripheral, and enteric.
- The central nervous system (CNS) includes the brain and spinal cord.
- The peripheral nervous system (PNS) has afferent (sensory) and efferent (motor) divisions.
- The somatic nervous system controls voluntary actions, whereas the autonomic nervous system controls involuntary actions.
- The autonomic nervous system can be further subdivided into sympathetic and parasympathetic components.
- The enteric nervous system controls digestion.
Cellular Components of CNS and PNS
- Glial cells make up 90% of the volume of the brain.
- Glial cells support neurons structurally and metabolically.
- Astrocytes are star-shaped glial cells that are crucial for maintaining the proper spatial relationships within the CNS.
- Astrocytes form the blood-brain barrier (BBB).
- The BBB regulates the passage of materials from the blood to the brain.
- Oligodendrocytes produce myelin sheaths around axons.
- Microglia are involved in removing foreign invaders or tissue debris.
- Ependymal cells create cerebrospinal fluid (CSF).
- CSF provides cushioning for the brain and spinal cord.
Gray and White Matter
- Grey matter consists of densely packed cell bodies (non-myelinated).
- White matter is composed of myelinated axons.
- The brain's cortex (outer layer) is mostly grey matter, while the interior is predominantly white matter.
- The spinal cord exhibits superior white matter and interior grey matter.
Protection of CNS
- The cranium (skull) and vertebral column protect the CNS.
- The meninges (dura mater, arachnoid mater, pia mater) are protective membranes surrounding the CNS.
- CSF (cerebrospinal fluid) cushions and protects the brain and spinal cord.
- The blood-brain barrier (BBB) selectively controls the entry of substances into the brain.
The Blood-Brain Barrier (BBB)
- Astrocytes form the blood-brain barrier by surrounding brain capillaries.
- Tight junctions between endothelial cells of brain capillaries limit the movement of substances.
- Lipid-soluble substances (like oxygen, carbon dioxide, alcohol, and steroids) readily pass through the BBB.
- The BBB protects the brain from harmful substances in blood and limits the penetration of many drugs.
- The pituitary and hypothalamus are not fully protected by the BBB.
Cerebrospinal Fluid (CSF)
- CSF is produced by choroid plexuses in brain ventricles.
- It flows through the ventricles and spinal cord, providing cushioning and buoyancy.
- CSF is reabsorbed into the dural sinuses.
Brain Injury
- Coup injuries occur when the brain strikes the skull on the side of impact.
- Contrecoup injuries occur when the brain strikes the opposite side of the skull.
Cerebral Spinal Fluid (CSF) Composition
- CSF has a similar composition to plasma, but with key differences in ion concentrations (like lower K+).
- It contains trace amounts of protein and facilitates ion transport for proper impulse formation.
Organization of the Brain
- The brain stem controls basic life functions.
- The cerebellum coordinates motor activity.
- The diencephalon includes the hypothalamus (involved in homeostasis) and the thalamus (sensory processing).
- The cerebrum is the largest part of the brain and is associated with higher-level functions like decision making.
Characteristic of Cerebral Cortex
- The cerebral cortex is highly convoluted, with gyri (folds) and sulci (grooves).
- It is divided into 6 layers based on neuronal distribution and functional differences.
- The left and right hemispheres of the cerebrum are connected by the corpus callosum.
Types of Neurons
- Neurons are classified structurally by the number of processes (axons and dendrites).
- Pseudounipolar neurons have a single process that branches into an axon and dendrite.
- Bipolar neurons have one axon and one dendrite.
- Multipolar neurons have multiple dendrites and one axon.
- Neurons can also be classified functionally as motor, sensory, or interneurons.
Functional Areas of the Cortex
- The cortex is divided into lobes (frontal, parietal, occipital, and temporal).
- Specific regions within these lobes are responsible for particular functions, such as primary motor and somatosensory cortices.
Homunculus
- The homunculus depicts the amount of brain cortex devoted to sensory and motor functions for different body parts.
- The representation is uneven, with greater cortical area assigned to highly sensitive areas.
- The homunculus is unique to each individual, and its organization can be modified over time.
Interaction of Different Brain Parts
- Language involves both comprehension and expression, mediated by specific brain regions.
- Broca's area is responsible for speech production; Wernicke's area for comprehension.
- Damage to these areas can lead to aphasia, impacting language abilities.
Identifying Brain Regions for Specific Activity
- Functional Magnetic Resonance Imaging (fMRI) can detect changes in blood flow associated with neural activity in specific brain areas.
- These changes enable us to locate and identify brain regions involved in specific activities.
Spinal Cord
- The spinal cord is a long, cylinder-shaped nerve tissue that extends from the brain stem.
- It's protected by the vertebral column.
- Spinal nerves emerge from the spinal cord, connecting to different body parts.
- The spinal cord carries sensory and motor information.
- It also plays a vital role in reflex actions.
Structure of Spinal Cord
- Ascending tracts carry sensory information from the periphery to the brain.
- Descending tracts carry motor commands from the brain to the periphery.
- The spinal cord contains both afferent (sensory) and efferent (motor) fibres, organized in ascending and descending tracts.
Nerve vs Neuron
- A nerve is a bundle of peripheral neuronal axons, rather than a single component.
- Nerves are comprised of myelinated axons along with connective tissues.
- In contrast, neurons are individual cells that are part of a nerve.
Renewal of Neurons
- Most neurons are formed during embryonic development and typically don't regenerate.
- Neurogenesis (the creation of new neurons) does occur in specific brain regions, particularly the hippocampus.
- Ependymal cells may function as neural stem cells.
Review Points After Lecture
- The lecture covered the structure, components, functions, and protective mechanisms of the central and peripheral nervous systems (CNS & PNS).
- Core concepts and related functional regions of the brain were meticulously detailed.
- Important processes and functions of the brain and spinal cord, including sensory & motor pathways, were discussed.
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Description
Explore the intricacies of the nervous system, including its major components such as the central, peripheral, and enteric systems. Learn about the functions of glial cells, the significance of the blood-brain barrier, and the distinctions between the somatic and autonomic nervous systems. This quiz will help solidify your understanding of the foundational elements of neuroanatomy.
