Efferent Pathways in Nervous System

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Questions and Answers

Which of the following actions is associated with the sympathetic division of the autonomic nervous system?

  • Pupil Constriction
  • Bronchodilation (correct)
  • Salivation Stimulation
  • Heart Rate Reduction

What is the primary neurotransmitter released at the neuromuscular junction?

  • Serotonin
  • Dopamine
  • Acetylcholine (correct)
  • Norepinephrine

What characterizes the thick filaments in muscle fibers?

  • They are composed of actin.
  • They create the Z-lines.
  • They are involved in the sliding filament theory.
  • They are made up of myosin. (correct)

Which event occurs during muscle contraction?

<p>Actin filaments slide over myosin filaments. (B)</p> Signup and view all the answers

In the muscle fiber, what is primarily responsible for carrying nerve impulses from the brain?

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

Which option is a function of the parasympathetic division?

<p>Stimulation of Intestinal Motility (C)</p> Signup and view all the answers

What structural unit is responsible for the striated appearance of skeletal muscle?

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

What occurs at the motor end plate during muscle contraction?

<p>Release of neurotransmitters (D)</p> Signup and view all the answers

What is the primary function of the sympathetic nervous system?

<p>To produce the 'fight or flight' response (D)</p> Signup and view all the answers

Which neurotransmitter is primarily associated with the sympathetic nervous system?

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

Which statement best describes the autonomic nervous system?

<p>It regulates the functions of organs independently of will. (B)</p> Signup and view all the answers

What is a key difference between the somatic and autonomic nervous systems?

<p>The somatic nervous system innervates skeletal muscles. (B)</p> Signup and view all the answers

Which of the following is primarily controlled by the parasympathetic nervous system?

<p>Stimulated gastrointestinal activity (B)</p> Signup and view all the answers

What physiological response is primarily induced by sympathetic stimulation?

<p>Increased heart rate (C)</p> Signup and view all the answers

Which of the following components is a part of the peripheral nervous system?

<p>Spinal nerves (B)</p> Signup and view all the answers

In the context of the autonomic nervous system, which of the following accurately depicts the role of acetylcholine?

<p>It acts in the transmission of nerve impulses in the parasympathetic system. (A)</p> Signup and view all the answers

What initiates the muscle contraction process after the action potential is generated in the muscle fiber?

<p>Release of calcium ions from the sarcoplasmic reticulum (A)</p> Signup and view all the answers

Which of the following accurately describes a primary difference between the nervous and endocrine systems?

<p>The endocrine system operates through blood vessels while the nervous system uses neural pathways. (C)</p> Signup and view all the answers

In neuroendocrine regulation, what role does the adrenal gland primarily play?

<p>It releases adrenaline and cortisol into the blood. (D)</p> Signup and view all the answers

Which statement correctly describes the effect of signals produced by the nervous system compared to the endocrine system?

<p>Nervous system effects are rapid but of short duration. (C)</p> Signup and view all the answers

What is described as a situation where both the nervous and endocrine systems interact for a physiological response?

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

Which components make up the effector tissues for the endocrine system?

<p>Target tissues with hormonal receptors (B)</p> Signup and view all the answers

What term is used to describe stimuli that trigger a stress response in the body?

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

Which function does the sarcolemma serve in muscle fibers?

<p>It transmits electrical signals. (A)</p> Signup and view all the answers

Flashcards

Efferent pathways

Nerves that carry information from the central nervous system toward the organs.

Sympathetic Nervous System

The part of the nervous system responsible for the 'fight or flight' response.

Parasympathetic Nervous System

The part of the nervous system responsible for regulating normal, restful body functions.

Adrenaline and Noradrenaline

The neurotransmitter used in the sympathetic nervous system, responsible for the 'fight or flight' response.

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Acetylcholine

The neurotransmitter used in the parasympathetic nervous system, responsible for restful body functions.

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Afferent pathways

The type of nerve that carries information towards the central nervous system.

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Cranial nerves

Afferent and efferent fibers make up this type of nerve.

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Spinal nerves

Afferent and efferent fibers make up this type of nerve.

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What is the cholinergic system?

The parasympathetic nervous system is also known as the cholinergic system because it uses acetylcholine as its primary neurotransmitter.

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What does the sympathetic nervous system do?

The sympathetic nervous system is responsible for the 'fight or flight' response, preparing the body for action and stress.

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What does the parasympathetic nervous system do?

The parasympathetic nervous system is responsible for 'rest and digest' functions, promoting relaxation and slowing down the body.

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What is the neuromuscular junction?

The neuromuscular junction is the specialized synapse where a motor neuron communicates with a muscle fiber, initiating muscle contraction.

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What are muscle fibers?

Muscle fibers are long, cylindrical cells that make up skeletal muscle tissue. They are responsible for muscle contraction.

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What are myofibrils?

Myofibrils are bundles of protein filaments within muscle fibers. They are responsible for muscle contraction.

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What is myosin?

Myosin is a protein that forms the thick filaments in myofibrils, responsible for muscle contraction.

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What is actin?

Actin is a protein that forms the thin filaments in myofibrils, responsible for muscle contraction.

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Sarcolemma

The membrane surrounding a muscle fiber, responsible for transmitting the action potential that triggers muscle contraction.

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Sarcoplasmic Reticulum

A network of internal membranes within a muscle fiber that stores and releases calcium ions (Ca²+) essential for muscle contraction.

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Neuroendocrine Regulation

The process by which the nervous and endocrine systems work together to regulate bodily functions.

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Stressors

External or internal stimuli that trigger a stress response in the body.

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Stress Response

The body's defense response to a stressor, involving the release of hormones and physiological changes aimed at coping with the threat.

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Hormones

Chemical messengers produced by endocrine cells that travel through the bloodstream to target tissues.

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Nervous System

Specialized cells (neurons) that transmit signals through electrical impulses for rapid communication.

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Endocrine System

The system of glands (endocrine cells) that produce hormones, regulating long-term and widespread effects.

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Study Notes

Efferent Pathways

  • Nervous system information flow: Information entering or leaving the central nervous system travels along nerves comprising the peripheral nervous system.
  • Afferent vs. Efferent: Nerves carrying information to the brain/spinal cord are afferent. Nerves carrying information from the central nervous system to effector organs are efferent.
  • Cranial and Spinal Nerves: Nerves originating from the brain or spinal cord, respectively, contain both afferent and efferent fibers.
  • Efferent Pathway Subdivision: Efferent pathways are categorized based on the target: somatic nervous system for skeletal muscles; autonomic nervous system for smooth muscle, cardiac muscle, and glands
  • Autonomic Nervous System (ANS): This system regulates organ function in response to environmental changes using antagonistic mechanisms (sympathetic and parasympathetic). It operates independently of conscious control.

Autonomic Nervous System (ANS)

  • General Function: The ANS regulates organ function in response to environmental changes.
  • Sympathetic Nervous System: ("Fight or Flight") Increases physiological activity during stress. Effects include increased blood pressure, heart rate, pupil dilation, respiration, and piloerection. Uses adrenaline and noradrenaline as neurotransmitters (adrenergic).
  • Parasympathetic Nervous System: Coordinates normal body functions during rest. Effects include decreased breathing and heart rate, stimulation of digestive system, urination and defecation. Uses acetylcholine as neurotransmitter (cholinergic).

Neuromuscular Junction

  • Muscle Structure: Skeletal muscle is composed of muscle fibers (cells) containing myofibrils (protein filaments). These filaments are arranged in sarcomeres, the basic contracting units.
  • Muscle Contraction: Muscle contraction involves sliding filaments of actin over myosin, shortening the sarcomere.
  • Neuromuscular Junction Function: Nerves control skeletal muscle contraction via neuro-muscular junctions. Motor neuron action potentials release acetylcholine which triggers an action potential in the muscle fiber.
  • Calcium Release: Muscle action potential causes calcium release from the sarcoplasmic reticulum.
  • Contraction Mechanism: Calcium initiates the myosin-actin interaction resulting in muscle contraction.
  • Relaxation: Calcium is removed and the muscle relaxes.

Neuroendocrine Regulation

  • Nervous and Endocrine Systems: The nervous system regulates quickly, via nerve impulses, while the endocrine system uses hormones and takes longer.
  • Neuroendocrine Regulation: In many cases they work together to coordinate a response to stressors (e.g., stress response).
  • Stress response: The nervous system initially responds to stressors, while the endocrine system provides a longer-lasting response by activating hormones.
  • Examples: Adrenal hormones (adrenaline/noradrenaline and cortisol) released by the endocrine system help sustain the faster response from the nervous system.

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