PHO221 Lecture 3: Nervous System Overview
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Questions and Answers

What is the primary function of dendrites in a neuron?

  • Generate electrical impulses
  • Receive signals from other neurons (correct)
  • Transmit signals to other neurons
  • Produce the myelin sheath

What role do Schwann cells play in neuron function?

  • They produce the myelin sheath (correct)
  • They release neurotransmitters
  • They receive signals from other neurons
  • They generate impulses in neurons

How do chemical synapses predominantly communicate messages?

  • By ions flowing directly between cells
  • By altering the structure of the neurons
  • Through electrical impulses generated by axons
  • Using chemical messengers called neurotransmitters (correct)

What occurs at the axon hillock in a neuron?

<p>Electrical impulses are generated (C)</p> Signup and view all the answers

Which of the following statements about synapses is correct?

<p>Most synapses communicate using chemical messengers (D)</p> Signup and view all the answers

What is the primary function of the relay neuron in the reflex arc?

<p>To connect sensory neurons to motor neurons (C)</p> Signup and view all the answers

What characterizes a reflex action?

<p>It happens almost instantaneously and involuntarily (B)</p> Signup and view all the answers

Which of the following best describes the path taken by nerve impulses during a reflex action?

<p>The reflex arc involving spinal cord synapses and motor neurons (C)</p> Signup and view all the answers

How does the brain influence reflex actions, despite not being directly involved?

<p>It can completely override the reflex action (D)</p> Signup and view all the answers

In higher animals, what is the advantage of sensory neurons synapsing in the spinal cord rather than passing directly into the brain?

<p>It allows for quicker reflex actions (B)</p> Signup and view all the answers

Which part of the brain is primarily responsible for muscle control and balance?

<p>Cerebellum (C)</p> Signup and view all the answers

What is the function of the hypothalamus?

<p>Regulating hormones and homeostasis (A)</p> Signup and view all the answers

Which cranial nerve is responsible for the sense of smell?

<p>Olfactory nerve (C)</p> Signup and view all the answers

In which part of the central nervous system is grey matter predominantly located?

<p>Outer layers of the brain (A)</p> Signup and view all the answers

What is the primary function of the cerebrum?

<p>Processing sensory information (B)</p> Signup and view all the answers

Which cranial nerve plays a crucial role in motor functions for the face?

<p>Facial nerve (B)</p> Signup and view all the answers

Which structure connects the brain and spinal cord?

<p>Medulla (A)</p> Signup and view all the answers

Which of the following structures is included in the subcortical structures of the brain?

<p>Olfactory bulb (B)</p> Signup and view all the answers

Which nerve is considered vital for hearing?

<p>Vestibulocochlear nerve (B)</p> Signup and view all the answers

The cerebrum is composed of which main parts?

<p>Cerebral cortex and cerebral hemispheres (A)</p> Signup and view all the answers

What is the role of the vagus nerve?

<p>Origin of the parasympathetic nervous system (A)</p> Signup and view all the answers

Which structure is NOT a part of the cerebral cortex?

<p>Hippocampus (C)</p> Signup and view all the answers

What role does the basal ganglia play in the brain?

<p>Facilitating voluntary motor control (C)</p> Signup and view all the answers

Which of the following is a correct description of the telencephalon?

<p>It encompasses the cerebral cortex and basal ganglia. (A)</p> Signup and view all the answers

What is the largest part of the human brain?

<p>Cerebrum (C)</p> Signup and view all the answers

Which subcortical structure is involved in memory formation?

<p>Hippocampus (C)</p> Signup and view all the answers

What property of neurons allows them to respond to stimuli?

<p>Excitability/Irritability (A)</p> Signup and view all the answers

Which statement describes the 'All or none law' in relation to action potentials?

<p>An action potential occurs fully or not at all once the threshold is reached. (A)</p> Signup and view all the answers

In myelinated nerve fibers, what process contributes to the faster velocity of impulse transmission?

<p>Localized depolarization occurring only at nodes. (A)</p> Signup and view all the answers

What is the primary role of the myelin sheath surrounding nerve fibers?

<p>To prevent injury to the nerve fiber. (C)</p> Signup and view all the answers

What occurs during an action potential in excitable cells?

<p>A transient reversal in the membrane potential. (C)</p> Signup and view all the answers

Which type of stimulus is necessary to trigger an action potential?

<p>An adequate threshold stimulus. (B)</p> Signup and view all the answers

What effect does myelination have on the conduction of impulses?

<p>Allows for impulses to jump between nodes. (A)</p> Signup and view all the answers

Which of the following does NOT occur during the action potential of a nerve cell?

<p>A decrease in membrane permeability to sodium. (A)</p> Signup and view all the answers

What is the primary cause of resting membrane potential in neurons?

<p>Presence of negatively charged intracellular proteins (A)</p> Signup and view all the answers

During which phase of action potential is it impossible to generate another action potential?

<p>Absolute refractory period (B)</p> Signup and view all the answers

What occurs during the depolarization phase of an action potential?

<p>Sodium channels open and Na+ rushes into the cell (A)</p> Signup and view all the answers

What is the role of the Na+/K+ pump in neuron function?

<p>To maintain resting membrane potential by pumping Na+ out and K+ in (A)</p> Signup and view all the answers

What is hyperpolarization in the context of action potentials?

<p>An increase in membrane potential making it more negative (C)</p> Signup and view all the answers

What defines a reflex action?

<p>An involuntary movement in response to a stimulus (C)</p> Signup and view all the answers

What distinguishes the relative refractory period from the absolute refractory period?

<p>It can generate action potentials with sufficient stimulation (A)</p> Signup and view all the answers

How many neurons are typically involved in most reflex arcs?

<p>Three neurons (C)</p> Signup and view all the answers

Flashcards

Cerebrum

Largest part of the brain, containing the cerebral cortex and several subcortical structures.

Cerebral cortex

Outer layer of the cerebrum, divided into two hemispheres.

Telencephalon

Another name for the cerebrum.

Endbrain

Another name for the cerebrum.

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Subcortical structures

Brain structures located beneath the cerebral cortex.

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Hippocampus

Subcortical structure involved in memory.

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Basal ganglia

Subcortical structures involved in movement.

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Olfactory bulb

Subcortical structure involved in smell.

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Neuron Excitability

The ability of a neuron to respond to stimuli

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Neuron Conductivity

The transmission of an impulse along a neuron

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Neuron Secretion

The release of neurotransmitters from a neuron

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All-or-None Law

Neurons fire completely or not at all, with a stimulus exceeding the threshold.

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Refractory Period

The time neuron is unresponsive after firing, consisting of absolute and relative phases

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Myelin

Fatty tissue that insulates nerve fibers, speeding up impulse transmission by jumping between nodes of Ranvier.

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Action Potential

A rapid change in membrane potential, acting as the nerve impulse.

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Impulse Velocity in Myelinated Nerves

Faster than in unmyelinated nerves due to depolarization occurring at the Nodes of Ranvier, appearing as jumping impulses.

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Neuron Structure

Neurons have dendrites to receive signals, axons to transmit signals, and an axon hillock to generate impulses. Schwann cells produce myelin sheaths.

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Synapses

Synapses are junctions where neurons communicate. Most use chemical messengers (neurotransmitters), while some use direct ion flow.

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Neuron Function

Neurons are the fundamental units of the nervous system, transmitting electrical signals throughout the body.

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Chemical Synapse

In a chemical synapse, an impulse triggers neurotransmitter release. Neurotransmitters bind to the postsynaptic cell, changing its activity.

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Neuron Unit

A neuron is the basic functional and structural unit of the nervous system.

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Cerebrum location

The uppermost region of the central nervous system.

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Cranial Nerves

12 pairs of nerves connecting directly to the brain.

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Grey matter in spinal cord

Butterfly-shaped core of the spinal cord.

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Hippocampus's Role

Memory, learning, and emotion functions.

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Hypothalamus role

Regulates bodily functions like temperature and hunger

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Medulla function

Connects brain and spinal cord, controls basic functions like heartbeat.

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Cerebellum's function

Controls motor functions, balance, and movement.

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Spinal Cord Structure

Grey matter is found in core; white matter makes up the outer layers in the spinal cord.

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Reflex Arc

The nerve pathway involved in a reflex action, like pulling your hand away from a hot stove.

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Reflex Action

An involuntary, almost immediate response to a stimulus.

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Sensory Neuron

A neuron that transmits information from a stimulus to the spinal cord.

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Relay Neuron

A neuron in the spinal cord that connects sensory and motor neurons.

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Motor Neuron

Neuron that carries signal from spinal cord to muscles causing movement.

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Resting Membrane Potential

The difference in electrical charge across a neuron's membrane when it's not firing a signal – a state of relaxation.

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Depolarization

A change in membrane potential where the inside of the neuron becomes more positive.

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Repolarization

The return of the membrane potential to its resting state after depolarization.

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Hyperpolarization

A change in membrane potential where the inside of the neuron becomes more negative than the resting state.

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Action Potential

A brief reversal of membrane potential that serves as the nerve impulse.

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Refractory Period

The time after an action potential where it is difficult or impossible to trigger another action potential.

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Reflex Arc

An automatic response to a stimulus that doesn't involve conscious thought, a simple neural pathway.

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Spinal Cord Reflex

An involuntary and nearly instantaneous movement in response to a stimulus, routed through the spinal cord rather than the brain.

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Study Notes

Physiology and Pathophysiology (PHO221) - Lecture 3: Nervous System

  • Course information:
    • Course title: Physiology and Pathophysiology (PHO221)
    • Lecturer: Prof. Dr. Noha Nassar
    • Department: Pharmacology Department, Faculty of Pharmacy, MSA University
    • Semester: Fall 2024
    • Lecture number: 3
    • Topic: Nervous System

Interactive Methods

  • Teaching methods:

    • Explanations with Q&A to enhance student engagement
    • Videos and diagrams
    • Online quiz on Google Sheet

  • Video links:

    • (List of YouTube video links)

References

  • Textbook of Medical Physiology
  • Guyton and Hall Textbook of Medical Physiology

Nervous System Overview

  • The nervous system is comprised of two main parts:
    • Central nervous system (CNS): brain and spinal cord
    • Peripheral nervous system (PNS): all nerves outside the CNS
  • The CNS controls the body's functions by sending and receiving signals through nerves.

Nervous System Subdivisions

  • Autonomic nervous system:
    • Controls self-regulated, involuntary actions of internal organs, including glands and internal organs.
    • Further subdivided into sympathetic and parasympathetic divisions
  • Somatic nervous system:
    • Controls voluntary movements of skeletal muscles

Subdivisions of peripheral nervous system (PNS):

  • Sympathetic division:
    • Arousing actions
  • Parasympathetic division:
    • Calming actions

Divisions of the nervous system diagrammatically:

  • Illustrates the relationships among peripheral, central and autonomic and somatic systems

Diagrammatic descriptions:

  • Illustrates central parts of the brain and spinal cord
  • Illustrates different types of nerves
  • Diagram of nerve cells
  • Shows functions of the brain in overall diagram
  • Indicates location of CNS and PNS components

Human Brain: Major Divisions

  • Forebrain:
    • Processes sensory information, reasoning and problem solving
  • Midbrain:
    • Regulates movement and processes visual and auditory information
  • Hindbrain:
    • Regulates autonomic functions, relays sensory information, coordinates movement, and maintains balance

Human Brain: Subcortical Structures

  • Hippocampus: memory, learning and emotion
  • Hypothalamus: hormonal production, heart rate, body temperature, hunger, sleep-wake cycle
  • Medulla: connection between brain and spinal cord, transmitting signals, controlling autonomic activities (heartbeat, breathing)
  • Cerebellum: muscle control, balance, and movement

Human Brain: Lobes

  • Frontal lobe: problem-solving, emotions, reasoning, voluntary motor activity, judgment, speaking
  • Parietal lobe: right and left perception, sensation, reading, body orientation
  • Temporal lobe: understanding language, behavior, memory, hearing
  • Occipital lobe: vision, color perception

Human Brain: Brain Stem

  • Breathing, body temperature, digestion, alertness, sleep cycles, swallowing

Cranial Nerves

  • 12 pairs of nerves connecting brain to body
    • Olfactory nerve(smell), Optic nerve (eyes), Oculomotor nerve (eyes), Trochlear nerve (eyes), Trigeminal nerve (face sensory), Abducens nerve (eye), Facial nerve (face), Vestibulocochlear nerve (ear), Glossopharyngeal nerve (tongue, throat), Vagus nerve (organs), Accessory nerve (neck), Hypoglossal nerve (tongue)

Spinal Cord

  • Spinal cord structure, segmental organization
    • Cervical, thoracic, lumbar, sacral, coccygeal regions
  • Different nerves associated with regions of the spinal cord (regions, and functions)

Gray Matter and White Matter

  • Gray matter: neuronal cell bodies (40% of the brain)
  • White matter: bundles of nerve axons (60% of the brain)
  • Describes the location, composition and functions in spinal cord

Neuron Structure and Function

  • The neuron is the basic structural and functional unit of the nervous system.

    • Dendrites: receive signals
    • Cell body (soma): integrates signals
    • Axon: transmits signals
    • Myelin sheath: increases signal speed (Schwann cells produce)

  • Types:

    • Sensory: (afferent) receive internal and external stimuli, take signals to the CNS
    • Motor: (efferent) transmit signals from CNS to effectors (muscles and glands)
    • Interneurons: connect sensory and motor neurons

  • Types of neurons (diagrammatic description, types and function):

    • Unipolar, Bipolar and Multipolar neuron

Synapses

  • Neurons communicate at synapses.
  • Most synapses use chemical messengers (neurotransmitters).
  • Some synapses are electrical.

Action Potential

  • Brief reversal in the membrane potential that is transmitted along the axon
  • Occurs in nerve and muscle cells
  • Consists of depolarization, repolarization and hyperpolarization phases

Resting Membrane Potential

  • Electrical potential difference across the neuron's membrane when it's not sending a signal.
  • Maintained by ion pumps and channels.

Causes of Resting Membrane Potential

  • Differences in ion concentration across the membrane, especially Na+ and K+
  • Active transport by Na+/K+ pump
  • Ion channels (passive leak of ions)
  • Intracellular proteins with negative charges

Refractory Period

  • Time period after an action potential when the neuron cannot readily generate another action potential.
  • Two parts (absolute and relative)

Spinal Cord Reflexes

  • Involuntary and nearly instantaneous movements in response to a stimulus.
  • Reflex arcs involve sensory neurons, interneurons, and motor neurons.
  • Reflexes do not always require conscious thought processing

Reflex Arc Components

  • Stimulus: initial event
  • Receptor: detects stimulus
  • Sensory neuron: transmits information to the spinal cord
  • Relay neuron: transmits information within the spinal cord
  • Motor neuron: transmits information from spinal cord to effector
  • Effector: muscle that reacts to response

Neuroglia (Glial Cells)

  • Astrocytes
  • Ependymal Cells
  • Oligodendrocytes
  • Microglia

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Physiology and Pathophysiology (PHO221) Lecture 3 PDF

Description

This interactive quiz is based on Lecture 3 of Physiology and Pathophysiology (PHO221), focusing on the Nervous System. Students will explore the structure and functions of the central and peripheral nervous systems, supplemented by videos and diagrams for enhanced understanding.

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