Podcast
Questions and Answers
What percentage of the body's mass does the brain occupy?
What percentage of the body's mass does the brain occupy?
What is the average rate of action potentials per neuron in the cortex?
What is the average rate of action potentials per neuron in the cortex?
How much power does the CNS use, approximately?
How much power does the CNS use, approximately?
What constitutes the central nervous system (CNS)?
What constitutes the central nervous system (CNS)?
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What type of signals does the dorsal root of a spinal nerve carry?
What type of signals does the dorsal root of a spinal nerve carry?
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Which statement about the energy consumption of the CNS is correct?
Which statement about the energy consumption of the CNS is correct?
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Which of the following statements is true regarding the peripheral nervous system (PNS)?
Which of the following statements is true regarding the peripheral nervous system (PNS)?
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What does the ventral root of the spinal cord carry?
What does the ventral root of the spinal cord carry?
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How many neurons are estimated to be in the human brain?
How many neurons are estimated to be in the human brain?
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Which system controls visceral functions such as heart rate and breathing?
Which system controls visceral functions such as heart rate and breathing?
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How much of the brain's energy does it use compared to the heart's pumping blood?
How much of the brain's energy does it use compared to the heart's pumping blood?
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What percentage of neurons in the brain are typically firing at a given moment?
What percentage of neurons in the brain are typically firing at a given moment?
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What is a reason the CNS has low neuron firing rates?
What is a reason the CNS has low neuron firing rates?
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Which part of the nervous system can function independently despite getting input from the spinal cord?
Which part of the nervous system can function independently despite getting input from the spinal cord?
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What major function does the somatic nervous system serve?
What major function does the somatic nervous system serve?
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What is the primary role of glial cells in the nervous system?
What is the primary role of glial cells in the nervous system?
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What percentage of neurons does Dr. Herculano estimate the human brain contains compared to the previously thought 100 billion?
What percentage of neurons does Dr. Herculano estimate the human brain contains compared to the previously thought 100 billion?
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Which statement correctly describes the organization of gray matter in the central nervous system?
Which statement correctly describes the organization of gray matter in the central nervous system?
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What is the function of oligodendrocytes in the central nervous system?
What is the function of oligodendrocytes in the central nervous system?
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What is cerebrospinal fluid primarily contained within?
What is cerebrospinal fluid primarily contained within?
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Which part of the nervous system contains bundles of myelinated axons known as tracts?
Which part of the nervous system contains bundles of myelinated axons known as tracts?
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How many lateral ventricles are present in the brain?
How many lateral ventricles are present in the brain?
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What are clusters of neurons in the peripheral nervous system called?
What are clusters of neurons in the peripheral nervous system called?
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Which statement accurately represents the structural difference between gray matter and white matter?
Which statement accurately represents the structural difference between gray matter and white matter?
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What direction does the term 'dorsal' refer to in relation to the spinal cord?
What direction does the term 'dorsal' refer to in relation to the spinal cord?
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Which type of nuclei is located in the dorsal horn of the spinal cord?
Which type of nuclei is located in the dorsal horn of the spinal cord?
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What do ascending tracts in the spinal cord primarily carry?
What do ascending tracts in the spinal cord primarily carry?
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Where are the autonomic efferent nuclei located in the spinal cord?
Where are the autonomic efferent nuclei located in the spinal cord?
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Which nuclei are responsible for processing sensory information from internal organs?
Which nuclei are responsible for processing sensory information from internal organs?
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What is the primary component of white matter in the spinal cord?
What is the primary component of white matter in the spinal cord?
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What type of tracts remain within the spinal cord without ascending or descending?
What type of tracts remain within the spinal cord without ascending or descending?
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Which nuclei in the spinal cord send commands to skeletal muscle?
Which nuclei in the spinal cord send commands to skeletal muscle?
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Which structure is responsible for processing information between the sensory systems and the cerebral cortex?
Which structure is responsible for processing information between the sensory systems and the cerebral cortex?
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Which part of the brain is primarily involved in regulating behavioral drives and maintaining homeostasis?
Which part of the brain is primarily involved in regulating behavioral drives and maintaining homeostasis?
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What connects the two hemispheres of the brain and is composed of myelinated axons?
What connects the two hemispheres of the brain and is composed of myelinated axons?
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Which of the following structures is included in the diencephalon?
Which of the following structures is included in the diencephalon?
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Which structure is involved in controlling movement and is part of the cerebral gray matter?
Which structure is involved in controlling movement and is part of the cerebral gray matter?
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What is the outer layer of the cerebral gray matter known as?
What is the outer layer of the cerebral gray matter known as?
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Which gland secretes hormones and is considered part of the endocrine system?
Which gland secretes hormones and is considered part of the endocrine system?
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What distinguishes the functions of the left and right hemispheres of the brain?
What distinguishes the functions of the left and right hemispheres of the brain?
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Which lobe of the brain is primarily responsible for speech and writing?
Which lobe of the brain is primarily responsible for speech and writing?
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What is the role of the cingulate gyrus within the brain?
What is the role of the cingulate gyrus within the brain?
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Which brain region is not considered part of the limbic system?
Which brain region is not considered part of the limbic system?
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Which hemisphere of the brain is primarily associated with language and math skills?
Which hemisphere of the brain is primarily associated with language and math skills?
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What is one function of the amygdala within the limbic system?
What is one function of the amygdala within the limbic system?
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The limbic system is primarily concerned with which of the following?
The limbic system is primarily concerned with which of the following?
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Which of the following is NOT a lobe of the brain?
Which of the following is NOT a lobe of the brain?
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What type of analysis is often associated with the right hemisphere of the brain?
What type of analysis is often associated with the right hemisphere of the brain?
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Study Notes
Welcome to PSL300 Section 4: CNS and Senses
- Instructor: Douglas Tweed
- Testable material: Facts and concepts from the slides only.
- Excluded material: Text printed in gray on the slides.
- Additional resources: Watch lectures for longer explanations, and read Silverthorn's Human Physiology.
Central Nervous System (CNS)
- The CNS includes the brain and spinal cord.
- The brain accounts for approximately 86 billion neurons.
- The spinal cord contains roughly 1 billion neurons.
- The enteric nervous system has an estimated 100–600 million neurons.
- Glial cells support and protect neurons.
Question of the Day
- Why are only 4% of brain neurons active at any given moment? (This is a question, not information)
Outline
- Overview of the CNS: Anatomy and energy supply.
- Spinal cord: Structure, nuclei, tracts, and reflexes.
- Brain: Divisions (including brain stem and cerebrum).
Overview of the CNS (cont.)
- The CNS is the brain and spinal cord. Diagrams show a human brain and spinal cord.
Peripheral Nervous System (PNS)
- Neurons outside the CNS comprise the PNS.
- The PNS includes the somatic (voluntary actions) and autonomic nervous systems.
- The enteric nervous system is part of the autonomic system and controls digestion It's independent.
CNS Composition
- The brain and spinal cord have a vast number of neurons.
- Most neurons reside within the CNS.
- The CNS and PNS also include glial cells, with abundance comparable to the neurons.
CNS Ventricles
- The CNS contains ventricles filled with cerebrospinal fluid (CSF).
- The ventricles include: Lateral ventricles, Third ventricle, Fourth ventricle and Central canal of spinal cord
Gray and White Matter
- Gray matter: nerve cell bodies, unmyelinated axons, and dendrites.
- White matter: myelinated axons in bundles (called tracts)
- Ganglia are clusters of neurons (in the peripheral nervous system)
CNS Energy Use
- The CNS uses a significant amount of energy.
- It has a high metabolic rate, using roughly 15% of cardiac output, and half the body's glucose, despite only being 2% of the body's mass.
- Compared to computers, the CNS consumes very little energy, around 40 watts.
Spinal Cord
- The spinal cord has 31 segments each with a pair of spinal nerves.
- Each spinal nerve has a dorsal root (incoming sensory signals) with a dorsal root ganglion, containing cell bodies of the sensory neurons.
- The ventral root (outgoing, motor signals) connects to skeletal muscles.
Spinal Reflexes
- A spinal reflex provides a quick response to a stimulus without the brain's direct involvement, as in the knee jerk reflex.
- Sensory fibers carry stretch signals relayed via interneurons towards the ventral horn which activates signals to leg muscles to counter the stretch.
Brain
- The brain has six major divisions: Cerebrum, Diencephalon, Midbrain, Pons, Medulla, and Cerebellum
Brain Stem
- The medulla, pons, and midbrain form the brain stem.
- The brain stem is central to autonomic functions like breathing, swallowing, and regulating blood pressure.
- Cranial nerves III–X and XII emerge from the brain stem.
Cranial Nerves
- Cranial nerves connect to the brain, not the spinal cord.
- There are 12 pairs.
Diencephalon
- The diencephalon comprises the thalamus, hypothalamus, pituitary, and pineal glands.
- The thalamus processes sensory information routed to the cerebral cortex.
- The hypothalamus regulates behavioral drives and homeostasis. The pituitary and pineal glands secrete hormones.
Cerebrum
- The cerebrum is divided into two hemispheres joined by the corpus callosum.
- Gray matter in the cerebrum includes the cortex, limbic system (aimed at emotion, motivation, and memory) and deep structures like basal ganglia related to movement control.
Cerebral Lateralization
- The two hemispheres exhibit specialization in function (left and right brain).
Lobes of the Cerebrum
- Each hemisphere has four lobes (frontal, parietal, temporal, and occipital.)
Limbic System
- The limbic system is a group of brain regions including the cingulate gyrus, amygdala, and hippocampus, related to emotion, memory, and motivation.
Reading in Silverthorn's Human Physiology
- Consult specific sections in Silverthorn's Human Physiology 8th edition. The chapters specified in pages 274, 289–290, and relevant sections 9.4 and 9.5 provide details on CNS. Similar guidance for 6th and 7th edition is also described.
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Description
Test your knowledge on the central and peripheral nervous systems with this quiz. Explore topics such as neuron function, brain energy consumption, and nervous system anatomy. Ideal for students studying neuroscience or related fields.
