Nervous System Structure and Function

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Questions and Answers

What roles do adrenergic receptors play in the body?

  • Stress response and energy mobilization (correct)
  • Mood regulation and gastrointestinal motility
  • Heart rate reduction and relaxation
  • Renal blood flow and motor control

Which pathway leads to the production of epinephrine?

  • Tyrosine → Dihydroxyphenylalanine → Dopamine → Norepinephrine → Epinephrine (correct)
  • Choline → AcetylCholine
  • Histidine → Histamine
  • Tryptophan → 5-Hydroxytryptophan → Serotonin

What neurotransmitter is predominantly released by the parasympathetic nervous system to affect heart rate?

  • Norepinephrine
  • Dopamine
  • Serotonin
  • Acetylcholine (correct)

In the autonomic nervous system, what is the primary role of serotonin?

<p>Mood regulation and gastrointestinal motility (C)</p> Signup and view all the answers

Which autonomic pathway is responsible for influencing heart rate during moments of crisis?

<p>Sympathetic nervous system activation (C)</p> Signup and view all the answers

Which receptors are primarily associated with the dopaminergic pathway?

<p>D1-D5 receptors (C)</p> Signup and view all the answers

What is the site of action for Acetaminophen (Paracetamol)?

<p>Brain and spinal cord (B)</p> Signup and view all the answers

Which neurotransmitter's pathway includes the enzyme Tryptophan-5-hydroxylase?

<p>Serotonin (D)</p> Signup and view all the answers

What mechanism do adrenergic receptors primarily utilize for signaling?

<p>cAMP-dependent signaling (B)</p> Signup and view all the answers

During the rest state, which division of the autonomic nervous system is dominant?

<p>Parasympathetic nervous system (B)</p> Signup and view all the answers

What type of neurons are found in the Posterior Root of the spinal column?

<p>Sensory neurons (D)</p> Signup and view all the answers

Which root of the spinal column contains motor neurons?

<p>Ventral Root (A), Anterior Root (C)</p> Signup and view all the answers

In the Reflex Arc, which component follows the Sensory Neuron?

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

Where do the sympathetic and parasympathetic nervous systems originate?

<p>Thoracolumbar and Craniosacral regions respectively (D)</p> Signup and view all the answers

Which type of receptors are activated by Acetylcholine in the pre-ganglionic neurons of both sympathetic and parasympathetic systems?

<p>Nicotinic receptors (B)</p> Signup and view all the answers

What is the characteristic of post-ganglionic neurons in the sympathetic nervous system?

<p>Long and non-myelinated (D)</p> Signup and view all the answers

What effect does the parasympathetic system typically have on physiological functions?

<p>Decrease and constrict (D)</p> Signup and view all the answers

Which neurotransmitter is primarily associated with adrenergic post-ganglionic neurons?

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

What is the role of the adrenal medulla in the sympathetic nervous system?

<p>Releases Epinephrine and Norepinephrine into bloodstream (C)</p> Signup and view all the answers

What does 'autonomic tone' refer to in autonomic motor neurons?

<p>A resting level of activity without stimulation (B)</p> Signup and view all the answers

Flashcards

Posterior Root (Dorsal Root)

The dorsal root of the spinal cord, containing sensory neurons that carry information from the body to the central nervous system.

Spinal (Dorsal) Root Ganglion

A cluster of sensory neuron cell bodies located within the dorsal root ganglion, relaying sensory information to the spinal cord.

Anterior Root (Ventral Root)

The ventral root of the spinal cord, containing motor neurons that carry commands from the central nervous system to muscles and glands.

Motor Neurons

Neurons that transmit signals from the central nervous system to muscles and glands, causing them to act.

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Sensory Neurons

Neurons that transmit signals from sensory receptors in the body towards the central nervous system, carrying information about the environment.

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Reflex Arc

A neural pathway that controls a reflex action, involving a sensory receptor, sensory neuron, interneuron in the CNS, motor neuron, and effector.

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Autonomic Nervous System (ANS)

The part of the nervous system responsible for controlling involuntary actions, such as heart rate, digestion, and breathing.

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Sympathetic Nervous System

A branch of the autonomic nervous system that prepares the body for 'fight-or-flight' response, increasing heart rate, dilating pupils, and releasing adrenaline.

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Parasympathetic Nervous System

A branch of the autonomic nervous system that promotes 'rest and digest' response, slowing heart rate, constricting pupils, and promoting digestion.

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Autonomic Tone

The spontaneous level of activity in autonomic motor neurons, even in the absence of stimulation. It influences various physiological processes like heart rate and digestion.

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Autonomic Plexuses

Nerve networks found in the thoracic and abdominopelvic cavities, formed by SNS post-ganglionic and PNS pre-ganglionic fibers, traveling along blood and lymphatic vessels that supply visceral organs.

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Dual Innervation

The state where a particular organ receives input from both the sympathetic and parasympathetic nervous systems, allowing for fine-tuned control.

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Parasympathetic Control of Heart Rate

The release of acetylcholine (ACh) by the parasympathetic nervous system to slow down the heart rate.

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Sympathetic Control of Heart Rate

The release of norepinephrine (NE) by the sympathetic nervous system to accelerate the heart rate.

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PNS Dominance at Rest

The dominant influence of the parasympathetic nervous system during rest.

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Sympathetic Stimulation and PNS Inhibition in Crisis

The sympathetic nervous system's stimulation and parasympathetic system's inhibition during moments of stress or crisis.

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Serotonin

Neurotransmitter used in the nervous system, mainly involved in mood, sleep, and appetite. It interacts with receptors 5-HT1 through 5-HT7.

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Epinephrine Pathway

A pathway that converts tyrosine into epinephrine, involving multiple enzymes and intermediate steps.

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Histamine Pathway

A pathway where histidine is converted into histamine, utilizing the enzyme histidine carboxylase.

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Study Notes

Spinal Cord Structure

  • The posterior root is the dorsal root, containing sensory neurons
  • The spinal (dorsal) root ganglion also contains sensory neurons
  • The anterior root is the ventral root, containing motor neurons
  • Motor neurons send signals out of the central nervous system (CNS)
  • Sensory neurons carry messages to the brain

Reflex Arc

  • Sensory receptor detects stimuli
  • Sensory neuron transmits signal to CNS
  • Information processing occurs in CNS
  • Motor neuron carries signal
  • Effector (muscle) responds

Sympathetic Nervous System (SNS)

  • Originates in the thoracolumbar region (T1-L2)
  • Pre-ganglionic fibers are short and myelinated
  • Post-ganglionic fibers are long and non-myelinated
  • Pre-ganglionic neurons are cholinergic, nicotinic
  • Post-ganglionic neurons are adrenergic
  • Generally increases and dilates

Parasympathetic Nervous System (PNS)

  • Originates in the craniosacral region
  • Pre-ganglionic fibers are long and myelinated
  • Post-ganglionic fibers are short and non-myelinated
  • Pre-ganglionic neurons are cholinergic, nicotinic
  • Post-ganglionic neurons are cholinergic, muscarinic
  • Generally decreases and constricts

Neurotransmitters

  • Acetylcholine (ACh) primarily in the preganglionic neurons of both systems, and some postganglionic in the PNS
  • Some postganglionic neurons release Norepinephrine or Epinephrine (SNS)
  • These responses can be excitatory or inhibitory, depending on the target organ and receptor type

Autonomic Tone

  • Autonomic motor neurons maintain a background level of activity
  • This is important in situations where dual innervation is present

Dual Innervation

  • Heart, blood vessels, and other visceral organs receive input from both sympathetic and parasympathetic branches
  • Autonomic plexuses are nerve networks in thoracic and abdominopelvic cavities formed by pre and post ganglionic fibers
  • ACh (parasympathetic) usually slows heart rate. NE (sympathetic) accelerates heart rate.

Autonomic Pathways

  • Parasympathetic and sympathetic pathways vary
    • Pathway a shows parasympathetic, b sympathetic, c adrenal pathway
  • Autonomic targets: smooth and cardiac muscles, some glands and adipose tissues

Neurotransmitters and Receptor Types

  • Sympathetic division uses norepinephrine, which binds to adrenergic receptors (alpha and beta)
  • Parasympathetic division uses acetylcholine, which binds to cholinergic receptors (nicotinic and muscarinic)
  • Specific receptors and their effects vary
    • Norepinephrine effects are often alpha or beta, and acetylcholine effects are muscarinic.

Additional Info

  • Norepinephrine(NE), a prominent neurotransmitter, has specific receptor types (α, β) affecting physiological responses
  • Specific enzyme pathways for NE (tyrosine → dopamine → norepinephrine) and other neurotransmitters(serotonin, histamine) are shown
  • Different neurotransmitter pathways exist (histamine, serotonin) with distinct origins, synthesis, and actions

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