Nervous System Overview (VII)
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Questions and Answers

The response of the pupils of the eyes to light is a reflex of this type known as ______.

reflex

The adult brain weighs a little over ______ pounds.

3

The largest and most complex mass of nervous tissue in the body is the ______.

brain

The surface of the cerebrum exhibits elevated ridges called ______.

<p>gyri</p> Signup and view all the answers

The cerebral hemispheres are separated by the ______ fissure.

<p>longitudinal</p> Signup and view all the answers

The nervous system is the master control and communication system of the body, reflecting every thought, action, and ______.

<p>emotion</p> Signup and view all the answers

Beneath the cerebral hemispheres lies the ______ and the brain stem.

<p>diencephalon</p> Signup and view all the answers

Less numerous than gyri are the deeper grooves called ______.

<p>fissures</p> Signup and view all the answers

The nervous system communicates with body cells using ______ impulses.

<p>electrical</p> Signup and view all the answers

The endocrine system produces ______ that are released into the blood.

<p>hormones</p> Signup and view all the answers

Reflex testing is an important tool for evaluating the condition of the ______ system.

<p>nervous</p> Signup and view all the answers

The nervous system uses sensory receptors to monitor changes called ______.

<p>stimuli</p> Signup and view all the answers

The process of interpreting sensory input is known as ______.

<p>integration</p> Signup and view all the answers

The central nervous system consists of the brain and ______.

<p>spinal cord</p> Signup and view all the answers

The peripheral nervous system includes all parts of the nervous system ______ the CNS.

<p>outside</p> Signup and view all the answers

Spinal nerves carry impulses to and from the spinal ______.

<p>cord</p> Signup and view all the answers

The cerebellum is responsible for controlling our ______.

<p>balance</p> Signup and view all the answers

The outer cortex of the cerebellum is made up of ______ matter.

<p>gray</p> Signup and view all the answers

When the cerebellum is sedated by alcohol, its ability to maintain coordination becomes ______.

<p>impaired</p> Signup and view all the answers

A blow to the head can cause damage to the cerebellum, resulting in a condition called ______.

<p>ataxia</p> Signup and view all the answers

The meninges are the three connective tissue membranes that cover and protect the ______ structures.

<p>CNS</p> Signup and view all the answers

The outermost layer of the meninges is known as the dura ______.

<p>mater</p> Signup and view all the answers

Cerebrospinal fluid serves to protect the brain and spinal cord by acting as a ______.

<p>cushion</p> Signup and view all the answers

The brain is protected from harmful substances by the ______-brain barrier.

<p>blood</p> Signup and view all the answers

The major positive ions inside the cell are ______, whereas the major positive ions outside the cell are sodium (Na+).

<p>potassium (K+)</p> Signup and view all the answers

When the inside remains more negative than the outside, the neuron will stay ______.

<p>inactive</p> Signup and view all the answers

Many different types of stimuli, such as light or sound, can excite neurons to generate an ______.

<p>impulse</p> Signup and view all the answers

Sodium ions cannot diffuse through the plasma membrane until the neuron is ______ stimulated.

<p>adequately</p> Signup and view all the answers

The inward rush of sodium ions changes the polarity of the neuron’s membrane, resulting in ______.

<p>depolarization</p> Signup and view all the answers

The nerve impulse is an all-or-none response; it is either propagated over the entire ______ or it doesn’t happen at all.

<p>axon</p> Signup and view all the answers

After sodium ions rush into the neuron, the membrane becomes impermeable to sodium ions but permeable to ______ ions.

<p>potassium</p> Signup and view all the answers

The outflow of positive ions restores the electrical conditions at the membrane to the polarized, or resting state, in an event called ______.

<p>repolarization</p> Signup and view all the answers

Each cerebral hemisphere has three basic regions: a superficial cortex of ______ matter, an internal area of white matter, and the basal nuclei.

<p>gray</p> Signup and view all the answers

Functions of the cerebral cortex include speech, memory, logical and emotional responses, ______, and voluntary movement.

<p>consciousness</p> Signup and view all the answers

The primary somatic sensory area is located in the ______ lobe posterior to the central sulcus.

<p>parietal</p> Signup and view all the answers

Impulses traveling from the body’s sensory receptors are localized and interpreted in this area of the brain called the primary somatic ______ area.

<p>sensory</p> Signup and view all the answers

A spatial map called the sensory ______ has been developed to show how much tissue is devoted to various sensory functions.

<p>homunculus</p> Signup and view all the answers

Body regions with the most sensory receptors, such as the ______ and fingertips, send impulses to a larger part of the sensory area.

<p>lips</p> Signup and view all the answers

The sensory pathways are ______ pathways, meaning that the left side of the sensory area receives impulses from the right side of the body.

<p>crossed</p> Signup and view all the answers

The primary somatic sensory area allows you to recognize ______, differences in temperature, or a light touch.

<p>pain</p> Signup and view all the answers

The parasympathetic division is often referred to as the '______' system of the body.

<p>housekeeping</p> Signup and view all the answers

The key functions of the parasympathetic division can be remembered by the letter '______'.

<p>D</p> Signup and view all the answers

The sympathetic division is associated with '______', excitement, emergency, and embarrassment.

<p>exercise</p> Signup and view all the answers

Maternal infection early in pregnancy can have harmful effects on the '______' system.

<p>nervous</p> Signup and view all the answers

Cerebral palsy is a neuromuscular disability resulting from damage to the '______'.

<p>brain</p> Signup and view all the answers

Cerebral palsy is the largest single cause of physical disabilities in '______'.

<p>children</p> Signup and view all the answers

The '______' rate of nervous tissue in the body is the highest.

<p>metabolic</p> Signup and view all the answers

A significant cause of potential brain damage in infants can arise from a '______' mother.

<p>smoking</p> Signup and view all the answers

Flashcards

Nervous System

The body's master control and communication system, using electrical impulses to regulate body functions.

Sensory input

Information gathered by sensory receptors about changes inside and outside the body.

Integration

The processing and interpretation of sensory input to determine the appropriate response.

Effectors

Muscles or glands that respond to the instructions sent by the nervous system.

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Central Nervous System (CNS)

The brain and spinal cord, which act as the body's integrating and command centers.

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Peripheral Nervous System (PNS)

All parts of the nervous system outside the CNS, mainly the nerves extending from spinal cord and brain.

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Spinal Nerves

Nerves that carry impulses to and from the spinal cord.

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Stimuli

Changes in the internal or external environment that trigger a response in the nervous system.

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Neuron resting state

The state of a neuron when it is not transmitting an impulse; the inside of the neuron is more negative than the outside.

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Depolarization

A change in the neuron's membrane potential where the inside becomes more positive than the outside, caused by the influx of sodium ions.

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Action potential

A rapid, large change in membrane potential that travels along a neuron; an 'all-or-none' response.

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Graded potential

A small, localized change in membrane potential; not a long-distance signal.

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Repolarization

The restoration of the resting membrane potential, where the inside of the neuron returns to a more negative state; caused by potassium outflow.

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Sodium-Potassium pump

A specialized pump that moves sodium ions out of the neuron while moving potassium ions in, which is essential for maintaining resting potential.

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Nerve impulse

Another term for action potential.

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Brain Reflexes

Some reflexes involve the brain evaluating multiple pieces of information to decide on the correct response.

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Pupil Reflex

The pupil's response to light is a reflex needing brain involvement.

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Reflex Testing

Assessing reflexes helps evaluate the health of the nervous system.

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Abnormal Reflexes

Exaggerated, distorted, or missing reflexes suggest nervous system problems

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Cerebral Hemispheres

The top part of the brain, the largest parts; they form the main part of the cerebrum.

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Cerebrum

Paired cerebral hemispheres collectively; top portion of brain

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Gyri and Sulci

Elevated ridges (gyri) and grooves (sulci) in the brain's surface.

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Longitudinal Fissure

The deep groove separating the two cerebral hemispheres

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Cerebral Cortex

The outer layer of the brain, responsible for higher-level functions like speech, memory, and voluntary movement.

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Gray Matter

The tissue that makes up the cerebral cortex, containing nerve cell bodies and unmyelinated axons.

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White Matter

The tissue found beneath the cerebral cortex, composed of myelinated axons that connect different areas of the brain.

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Basal Nuclei

Clusters of gray matter deep within the white matter, involved in controlling movement and coordination.

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Primary Somatic Sensory Area

The region in the parietal lobe responsible for receiving and interpreting sensory information from the body (except for special senses like sight, smell, taste, hearing, and balance).

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Sensory Homunculus

A distorted representation of the human body, illustrating the relative amount of brain tissue devoted to different sensory functions.

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Crossed Pathways

The phenomenon where sensory information from the right side of the body is processed in the left side of the brain, and vice versa.

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What does the primary somatic sensory area allow you to do?

It allows you to recognize pain, differences in temperature, or a light touch.

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Cerebellum's role

The cerebellum coordinates muscle activity for smooth movements and maintains balance.

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Cerebellum damage

Damage to the cerebellum can lead to ataxia, a condition characterized by clumsy, uncoordinated movements and difficulty maintaining balance.

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Why is the CNS protected?

The brain and spinal cord are delicate and can be easily damaged by pressure, so they are protected by bone, meninges, cerebrospinal fluid, and the blood-brain barrier.

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Meninges

Three connective tissue membranes that protect the CNS structures, acting as protective cushions.

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Dura mater

The outermost, tough layer of the meninges, providing strong protection to the CNS.

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Periosteal layer

One of the layers of the dura mater that attaches to the inner surface of the skull, helping to anchor the brain within the skull.

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Cerebrospinal fluid

A clear fluid that circulates around the brain and spinal cord, providing cushioning and protection.

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Blood-brain barrier

A selective barrier that protects the brain from harmful substances in the blood.

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Parasympathetic Division

The 'rest and digest' part of the autonomic nervous system, responsible for calming the body and conserving energy.

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Sympathetic Division

The 'fight or flight' part of the autonomic nervous system, preparing the body for action and stress.

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Dynamic Balance of ANS

The sympathetic and parasympathetic divisions don't work in an all-or-none fashion, but rather continuously adjust to maintain a balanced state.

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Maternal Infection's Impact

Maternal infections during early pregnancy can severely damage the fetal nervous system due to its rapid development.

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Oxygen Deprivation's Effect

Lack of oxygen, even for a short time, can cause significant damage to neurons due to their high metabolic rate.

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Smoking's Impact on Fetus

Smoking during pregnancy reduces oxygen supply to the fetus, potentially causing brain damage.

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Cerebral Palsy's Cause

Cerebral palsy, a neuromuscular disability, is often caused by temporary lack of oxygen during difficult deliveries.

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Cerebral Palsy's Symptoms

Cerebral palsy often causes poor muscle control, spasms, seizures, intellectual disability, and sensory impairments.

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Study Notes

Nervous System

  • The nervous system is the master control and communication system of the body, responsible for thoughts, actions, and emotions.

  • It communicates with body cells using electrical impulses which are rapid and specific.

  • The nervous system works with the endocrine system to maintain homeostasis. While the nervous system uses electrical nerve impulses, the endocrine system uses hormones released into the blood.

  • The nervous system has three main overlapping functions:

    • Sensory input: Monitoring internal and external changes using millions of sensory receptors.
    • Integration: Processing and interpreting sensory input.
    • Motor output: Activating effectors (muscles or glands) to cause a response.

Organization of the Nervous System

  • Structural Classification:

    • Central Nervous System (CNS): Brain and spinal cord; integrating and command centers.
      • Interprets sensory information and issues instructions.
    • Peripheral Nervous System (PNS): All nervous system components outside the CNS.
      • Cranial nerves carry impulses to/from the brain.
      • Spinal nerves carry impulses to/from the spinal cord.
      • Communication lines.
  • Functional Classification:

    • Sensory (Afferent) division: Carries impulses TO the CNS from sensory receptors.
      • Somatic sensory fibers: Impulses from skin, skeletal muscles, and joints
      • Visceral sensory fibers: Impulses from visceral organs.
    • Motor (Efferent) division: Carries impulses FROM the CNS to effector organs (muscles and glands).
      • Somatic nervous system: Voluntary control of skeletal muscles (also involuntary reflexes in skeletal muscles).
      • Autonomic nervous system: Involuntary control of cardiac and smooth muscle, glands.

Nerve Tissue

  • Composed of supporting cells (neuroglia or glia) and neurons.

  • Supporting cells (neuroglia/glia):

    • Astrocytes: Abundant, star-shaped cells support and anchor neurons.
    • Microglia: Spiderlike phagocytes monitor health and dispose of debris.
    • Ependymal cells: Line central cavities of brain and spinal cord; circulate cerebrospinal fluid.
    • Oligodendrocytes: Wrap nerve fibers in myelin sheaths in the CNS.
    • Satellite cells: Protect neuron cell bodies in the PNS.
    • Schwann cells: Surround fibers in the PNS; form myelin sheath
  • Neurons: Highly specialized cells transmit nerve impulses (action potentials).

    • Cell body (soma): Contains nucleus and metabolic center of the neuron.
    • Processes:
      • Dendrites: Transmit signals toward the cell body.
      • Axons: Conduct signals away from the cell body.

Processes

  • Neurons have varying length, from microscopic to 7 feet.
  • Dendrites are receptive regions receiving incoming messages (electrical signals) toward the cell body.
  • Axons are conducting regions carrying nerve impulses away from the cell body toward other neurons or effectors.
  • The end of an axon branches profusely forming hundreds of axon terminals. Axon terminals contain neurotransmitters.
  • Synapse: Functional junction between axon terminals and another neuron or effector cell.

Homeostatic Imbalance: Myelin Sheaths

  • Multiple sclerosis (MS): Gradual destruction of the myelin sheath.
    • Electrical current is short-circuited and signals don't reach the target.
    • Results in visual, speech, and motor control problems.
    • Caused by the body's immune system attacking proteins of the sheath.

Functional Classification of Neurons

  • Sensory neurons carry signals from receptors to the CNS.
  • Motor neurons carry signals from the CNS to effectors (muscles or glands).
  • Interneurons (association neurons) complete the communication pathway between sensory and motor neurons.

Physiology: Nerve Impulses

  • Irritability: The ability to respond to a stimulus and convert it into an electrical impulse.
  • Conductivity: The ability to transmit the impulse along the nerve fibers.

Physiology: Reflexes

  • Rapid, predictable, and involuntary responses to stimuli.
  • Include somatic reflexes (skeletal muscles involuntary responses).
  • Include autonomic reflexes (smooth and cardiac muscle, glands).
  • Have 5 essential components: Receptor, sensory neuron, interneuron, motor neuron, effector (target organ).

Central Nervous System Anatomy

  • Cerebral Hemispheres (cerebrum):
    • Largest and most superior region of the brain; divided into lobes.
    • Processes logical and emotional responses, sensations.
  • Diencephalon: Contains thalamus and hypothalamus.
    • Thalamus: Relay center for sensory impulses.
    • Hypothalamus: Regulates body temperature, water balance, etc.
  • Brain Stem: Midbrain, pons, and medulla oblongata.
  • Cerebellum: Posterior to the pons and medulla.

Protection of the Central Nervous System

  • Meninges: Protective membranes: dura mater, arachnoid mater, pia mater.
  • Cerebrospinal fluid (CSF): Watery "broth" with components similar to blood plasma; cushions the nervous tissue.
  • Blood-brain barrier: Special filtration system that isolates neurons from harmful substances in the blood.

Peripheral Nervous System Structure

  • Nerves: Bundles of neuron fibers outside the CNS.
  • Cranial nerves: Serve the head and neck.
  • Spinal nerves: Named for the region of the spinal cord they originate from.

Autonomic Nervous System

  • Regulates involuntary functions (smooth muscle, cardiac muscle, glands).
    • Parasympathetic Division: "Rest-and-digest".
      • Promotes digestion, elimination, and conserving energy.
    • Sympathetic Division: "Fight-or-flight".
      • Activates body during extreme situations (exercise, fear, injury).

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Explore the intricate functions and organization of the nervous system. This quiz covers sensory input, integration, and motor output, along with the structural classification of the Central Nervous System. Test your knowledge on how the nervous system maintains homeostasis in conjunction with the endocrine system.

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