2nd October 2019

britannica

15

What are the 3 major components of a reflex arc?

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Sensory cells carry afferent impulses to a central interneuron, which makes contact with a motor neuron. The motor neuron carries efferent impulses to the effector, which produces the response. Three types of neurons are involved in this reflex arc, but a two-neuron arc,…

Keeping this in consideration, what is the reflex arc and how does it work?

A motor neuron carries the message from the central nervous system to the effector. In a knee-jerk reflex arc the sensory neuron directly connects to the motor neuron in the spinal cord. This is called a simple reflex arc. from the spindle (receptor) to where it connects with the motor neuron in the spinal cord.

What are the five components of a reflex arc?

Receptor - sense organ in skin, muscle, or other organ.
Sensory neuron - carries impulse towards CNS.
Interneuron - carries impulse within CNS.
Motor neuron - carries impulse away from CNS.
Effector - structure by which animal responds (muscle, gland, etc).

What is the Monosynaptic reflex arc?

When a reflex arc consists of only two neurons, one sensory neuron, and one motor neuron, it is defined as monosynaptic. Monosynaptic refers to the presence of a single chemical synapse.

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What is a superficial reflex?

Superficial reflexes are motor responses to scraping of the skin. They are graded simply as present or absent, although markedly asymmetrical responses should be considered abnormal as well. Classic examples of superficial reflexes include the abdominal reflex, the cremaster reflex and the normal plantar response.

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Why do nerve impulses travel in one direction?

Neurotransmitters are molecules that fit like a lock and key into a specific receptor. The receptor is located on the next cell in the line. Therefore, nerve impulses cannot travel in the opposite direction, because nerve cells only have neurotransmitter storage vesicles going one way, and receptors in one place.

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How nerve impulses are transmitted?

The transmission of a nerve impulse along a neuron from one end to the other occurs as a result of electrical changes across the membrane of the neuron. The membrane of an unstimulated neuron is polarized—that is, there is a difference in electrical charge between the outside and inside of the membrane.

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What is the role of the brain in a reflex action?

The sensory nerves that detect the heat are connected to the nerves that move the muscles of the hand. Such a connection of detecting the signal from the nerves and responding to it quickly is known as reflex arc. Reflex arcs are formed in the spinal cord and the information reaches the brain and brain responses to it.

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Why is it important to have reflexes?

The Importance of Reflexes - Parents With Purpose. A reflex is an involuntary motor response to a sensory stimulus. Reflexes perform many jobs for our central nervous system. They protect us from danger, they help us move our body, they help us see, etc.

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What is a reflex action in science?

When a receptor is stimulated, it sends a signal to the central nervous system, where the brain co-ordinates the response. But sometimes, a very quick response is needed, one that does not need the involvement of the brain. This is a reflex action. Reflex actions are rapid and happen without us thinking.

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Which are functions of the spinal cord?

The spinal cord carries out two main functions: It connects a large part of the peripheral nervous system to the brain. Information (nerve impulses) reaching the spinal cord through sensory neurons are transmitted up into the brain.

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What do you mean by reflex action?

A reflex, or reflex action, is an involuntary and nearly instantaneous movement in response to a stimulus. The reflex is then an automatic response to a stimulus that does not receive or need conscious thought.

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What is meant by spinal reflex?

A reflex mediated by a nerve pathway with a sensory afferent to the spinal cord, linkages within the cord, and an efferent to muscle from the cord. Spinal reflexes commonly occur without brain influence.

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What happens in reflex action?

When a receptor is stimulated, it sends a signal to the central nervous system, where the brain co-ordinates the response. But sometimes a very quick response is needed, one that does not need the involvement of the brain. This is a reflex action. Reflex actions are rapid and happen without us thinking.

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What controls the autonomic nervous system?

The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal.

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What tissue is in the effector?

1. As defined by Sherrington, a peripheral tissue that receives nerve impulses and reacts by muscular contractioon, glandular secretion, or electric discharge (from an electric organ, as in the case of certain bony fishes such as the electric eel). 2.

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What is the major descending voluntary motor tract?

The pyramidal tract is the major descending voluntary motor tract. The primary motor cortex is located in the postcentral gyrus.

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How does a muscle cell know how to move?

The muscle cells move by contraction and relaxation by utilizing the energy in the form of ATP. During relaxation the muscle fibres come to their original position. Thismovement of muscles cells or the muscle fibres results in the movement of the body parts.

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What is the function of the stretch reflex?

The stretch reflex (myotatic reflex) is a muscle contraction in response to stretching within the muscle. It is a monosynaptic reflex which provides automatic regulation of skeletal muscle length. When a muscle lengthens, the muscle spindle is stretched and its nerve activity increases.

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What type of reflex causes blinking?

The corneal reflex, also known as the blink reflex, is an involuntary blinking of the eyelids elicited by stimulation of the cornea (such as by touching or by a foreign body), though could result from any peripheral stimulus.

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Why is it important for animals to have a reflex arc?

A reflex action often involves a very simple nervous pathway called a reflex arc. A reflex arc starts off with receptors being excited. They then send signals along a sensory neuron to your spinal cord, where the signals are passed on to a motor neuron. As a result, one of your muscles or glands is stimulated.

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What is the medical term for reflex?

2 a : an automatic and often inborn response to a stimulus that typically involves a nerve impulse passing inward from a receptor to the spinal cord and then passing outward from the spinal cord to an effector (such as a muscle or gland) without reaching the level of consciousness and often without passing to the brain.

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What happens in the reflex arc?

A motor neuron carries the message from the central nervous system to the effector. In a knee-jerk reflex arc the sensory neuron directly connects to the motor neuron in the spinal cord. This is called a simple reflex arc. from the spindle (receptor) to where it connects with the motor neuron in the spinal cord.

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What are the sensory receptors?

A sensory receptor is a structure that reacts to a physical stimulus in the environment, whether internal or external. It is a sensory nerve ending that receives information and conducts a process of generating nerve impulses to be transmitted to the brain for interpretation and perception.

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