12 Questions
What is the main role of efferent (motor) neurons within the reflex arc?
Transmit signals from the central nervous system to effector cells
Which of the following statements is true about autonomic motor neurons?
Control contraction of smooth muscles and gland secretion
What distinguishes somatic motor neurons from autonomic motor neurons?
Target cells they act on
Which type of motor neuron controls the contraction of skeletal muscles?
Somatic motor neurons
What is the function of efferent neurons in the reflex arc?
Initiate a response to a stimulus
Which neurons transmit signals from the central nervous system to effector cells like muscles and glands?
Efferent neurons
What is the main responsibility of autonomic motor neurons?
Regulating heart rate and blood pressure
How do sympathetic neurons differ from parasympathetic neurons?
Sympathetic neurons release norepinephrine, while parasympathetic neurons release acetylcholine.
Which neurotransmitter is released by parasympathetic neurons?
Acetylcholine
What distinguishes autonomic motor neurons from somatic motor neurons?
Autonomic motor neurons are smaller and lack myelin sheath compared to somatic motor neurons.
What is the primary function of sympathetic neurons when activated?
Dilating bronchioles and preparing for 'fight or flight' response
Why do autonomic efferent neurons play a crucial role within the reflex arc?
To allow for automatic responses without conscious control
Study Notes
Reflex Arc and Efferent (Motor) Neurons
The reflex arc is a neural pathway that governs automatic responses to stimuli without conscious control. It involves three main components: sensory receptors, interneurons, and motor effectors. In this context, we will focus on the role of efferent (motor) neurons within the reflex arc.
Efferent neurons are nerve fibers that transmit signals from the central nervous system (CNS) to effector cells, such as muscles and glands. They are responsible for initiating a response to a stimulus, such as causing a muscle to contract or a gland to release a substance. Efferent neurons can be either motor neurons or autonomic neurons, depending on their target cells.
Motor Neurons
Motor neurons are efferent neurons that transmit signals from the CNS to the muscles or glands. They are responsible for controlling voluntary movements and are divided into two types: somatic motor neurons and autonomic motor neurons.
Somatic Motor Neurons
Somatic motor neurons, also known as spinal motor neurons or alpha motor neurons, are efferent neurons that control the contraction of skeletal muscles. They are the largest type of motor neuron and typically have a myelin sheath, which allows for rapid and efficient transmission of signals to the muscles.
Autonomic Motor Neurons
Autonomic motor neurons, also known as postganglionic neurons, are efferent neurons that control the contraction of smooth muscles and the secretion of glands. They are part of the autonomic nervous system, which is responsible for regulating functions such as heart rate, blood pressure, and digestion. Autonomic motor neurons do not have a myelin sheath and are generally smaller than somatic motor neurons.
Autonomic Neurons
Autonomic neurons, also known as autonomic efferent neurons, are efferent neurons that control the contraction of smooth muscles and the secretion of glands. They are part of the autonomic nervous system and are divided into two types: sympathetic and parasympathetic neurons.
Sympathetic Neurons
Sympathetic neurons are efferent neurons that release the neurotransmitter norepinephrine. They are responsible for arousing the body and preparing it for the "fight or flight" response. When activated, they cause the dilation of bronchioles and the contraction of the sphincter of the iris, among other effects.
Parasympathetic Neurons
Parasympathetic neurons are efferent neurons that release the neurotransmitter acetylcholine. They are responsible for relaxing the body and returning it to a state of rest. When activated, they cause the contraction of the sphincter of the iris and the secretion of saliva, among other effects.
In summary, efferent (motor) neurons play a crucial role within the reflex arc, allowing for automatic responses to stimuli without conscious control. They are responsible for initiating a response to a stimulus, such as causing a muscle to contract or a gland to release a substance. Efferent neurons can be either motor neurons or autonomic neurons, depending on their target cells, and are further categorized into somatic and autonomic motor neurons, as well as sympathetic and parasympathetic neurons within the autonomic nervous system.
Test your knowledge on efferent (motor) neurons and the reflex arc, which are essential components of the neural pathway governing automatic responses to stimuli without conscious control. Explore the roles of somatic motor neurons, autonomic motor neurons, sympathetic neurons, and parasympathetic neurons in initiating responses to various stimuli.
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