A three-neuron reflex arc consists of a receptor, a sensory (afferent) neuron, and a motor (efferent) neuron. The reflex arc is designed to help keep the body safe, and is the mechanism that permits immediate responses to danger related stimuli. A conduction pathway of a reflex arc consists of the motor neuron innervation of the peripheral nervous system, and at least one association neuron from the central nervous system. After the conduction pathway, an impulse follows. The reflex arc is composed of a sensory receptor, sensory nerve, integrating center, motor nerve, and effector organ.
The sensory receptor detects the presence of a stimulus in the skin, muscle, or other organ. The sensory neuron, which is also the afferent neuron, carries sensory information to the central nervous system. The integrating center is found only in gray matter of the central nervous system in the brain or spinal cord. This is where information is processed, and the motor command to stimulate the effector is initiated. The motor neuron, also called the efferent neuron, carries the motor command to the effector organ. Finally, the effector organ carries out the response to the stimulus, which may be to a muscle, gland or adipose tissue.
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A simple reflex arc would be you touching a hot pan and automatically pulling your hand away, whereas a more complex reflex arc would be you stepping on a sharp object, you might pull your foot away quickly after you step on the object, then you might fall over depending on what you other leg is doing. Although, the interneuron also would synapse with motor neurons that control the muscles of your other leg to adjust your position so you do not fall. Then the interneurons synapses with other neurons will carry information about what just happened to the cerebellum and the cerebrum so you can become cautious of what happen and take the appropriate action that needs to be
Each individual nerve is made up of: afferent nerves and efferent nerves where afferent nerves transmit impulses towards the nervous system from different parts of the body and efferent nerves transmit impulses away from the nervous system to the different parts of the body. The autonomic nervous system is another type of PNS responsible for involuntary actions like movement of heart, lungs, etc.
The components of the nervous system that are involved in the physical sensation is the peripheral nervous system, which is divided into two groups they are, sensory and motor divisions. The sensory impulse moves through the body by stimulating a receptor in the skin, and it goes through the sensory neurons and also travels through the afferent fibers, the spinal cord and also into the brain.
A mechanoreceptor in the papillary layer of the dermis that responds to fine touch is a
These receptors record on a extensive form of sensory modalities including changes in temperature, stress, touch, sound, mild, style, odor, physique and limb actions, and even blood pressure and chemistry. Scientists have recognized for nearly a hundred thirty years that distinct afferent nerve fibers of the peripheral nervous procedure are in contact with specialized non neural receptive buildings which realize and transmit sensory knowledge from the periphery to the Central Nervous System. The non neural receptive structure in conjunction with its afferent nerve fiber is mainly called a
The part of the peripheral nervous system that carries sensory information to the CNS is designated
send this information to the central nervous system. The motor neurons in turn carry processed
* Sensory neurons or Bipolar neurons carry messages from the body's sense receptors (eyes, ears, etc.) to the CNS. These neurons have two processes. Sensory neuron account for 0.9% of all neurons. (Examples are retinal cells, olfactory epithelium cells.)
Receptor - is a body structure that monitors changes in a controlled condition and sends input in the form of nerve impulses to the control center Control
The CNS contains the brain and spinal cord. Its main functions include: processing, integrating, and coordinating sensory information and motor instructions. The sensory data conducts information that is being processed from internal and external conditions the body is experiencing. Motor commands regulate and control peripheral organs (skeletal muscles). The brain functions under memory, emotions, learning, and intelligence. The PNS consist of the neural tissue found outside of the CNS. It functions in sending data to the CNS which motor commands are than carried out to the peripheral tissues/systems. Multiple nerve fibers send sensory data and motor commands in the PNS. The nerves that assist with transmitting data include the cranial nerves and spinal nerve. However, the PNS can be divided into afferent (to bring in) and efferent (to bring out) divisions of transferring data. The afferent division functions in bringing in sensory data to the CNS. Sensory structures are receptors that detect internal/external environmental change and adjusting accordingly. The efferent division functions in carrying out motor commands from the CNS to glands, muscles, and adipose tissue. The efferent division contains somatic
The peripheral nervous system (PNS) is connected directly to the central nervous system, and consists of neurons and nerves that send information back and forth the CNS. Furthermore, the peripheral nervous system can be divided into two sections, the sensory nervous system and the motor nervous system. The Sensory The sensory nervous system is in charge of transmitting data from a variety of internal organs or from external stimuli to the central nervous system using sensory nervous cells. On the other hand, the cells of the motor nervous system (motor neurons), take the impulse from the CNS to effectors, which include glands and muscles. In addition, the motor nervous system can be further divided into the somatic nervous system, controls voluntary actions of the skeletal muscle and external sensory organs, whilst the autonomic nervous system operates
The autonomic system targets cardiac and smooth muscle as well as glandular tissue. A visceral reflex is an autonomic reflex in the efferent branch. The output of visceral reflex starts with the preganglionic fiber emerging from a lateral horn neuron in the spinal cord or in a cranial nucleus neuron in the brain stem to a ganglion followed by a postganglionic fiber projecting to a target effector. Autonomic reflexes are integrated into the brain and brain stem primarily in the hypothalamus, thalamus, and brain stem. These regions contain centers that coordinate body functions needed to maintain homeostasis; for example, the heart, breathing, maintenance of body temperature, and blood pressure. The brainstem contains the integrating centers
Balance is achieved and maintained by a complex set of senorimotor control systems that include sensory input from vision and motor output to the eye. Maintaining balance depends on information received by the brain from 3 peripheral sources:eyes, muscles and joints and vestibular organs. These information sources send signals to the brain in the form of nerve impulses from special nerve endings called sensory receptors. Sensory receptors in the retina are called rods and cones. When light strikes the rods and cones, they send impulses to the brain that provide visual cues identifying how a person is orientated in terms of other objects such as the tightrope. As sensory integration takes place, the brain stem transmits impulses to the muscles
The compound action potential adds up all the action potentials that each individual neuron experiences in the sciatic nerve. Different stimulus amplitudes cause different neurons to fire an action potential; this is due to the fact that each neuron has a different threshold potential, or the minimum voltage the neuron needs to fire an action potential. The individual neuron action potential is an ‘all-or-nothing’ event, but the CAP, as a summation of different individual neurons, is not. The CAP amplitude will increase with larger stimulus potentials because more neurons with higher individual thresholds will be recruited. For this frog sciatic nerve, there are three fiber types, A, B, and C. A fibers are further divided, in the order of decreasing diameter, into α, β, γ, and δ fibers. There is an inverse relationship between the diameter of the nerve fiber and the threshold potential: the larger the diameter, the lower the threshold. Thus, as the largest fibers, the Aα neurons will be the first to be stimulated at a low stimulus potential, and the Aδ neuron fibers will be the last to be recruited. Because the sciatic nerve is mostly composed of A fibers, the recruitment of A-subtype nerve fibers are more readily distinguishable from the data. The minimum potential required to stimulate the Aα fibers was between 75 mV and 80 mV. Once the stimulus potential reached 90 mV, Aβ neurons were recruited and contributed to the increase in amplitude of the CAP. At a stimulus
There are two groups of reflexes in the human body, with two ways to categorize each of them. Reflexes can either be inborn and connected through the nervous system, or they can be learned through practice. Another way to explain a reflexive category would be autonomic reflexes or somatic reflexes. Autonomic reflexes are those which are unaware to us and act on visceral organs of the body, whereas somatic reflexes involve skeletal muscle stimulation. Both types of reflexes are put into effect via the nervous system. (1)
head, and this apparatus sends a signal to the brain so that your reflex action