Reflexes theories

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1. GROUP 1 Daisy Barbon John Paolo Tenorio Anjanette Saplan Christian James Leaño Ellyn Mondares Rom Azusano Patricia Jazzeth Feudo Romel Dela Cruz Ancel David Kim Bullanday Ma. Micka Maminta

2. MOTOR CONTROL is the study of nature and cause of movement. Is the systematic regulation of movement in organisms that possess nervous system. As a field of study is primary a sub—discipline of psychology or neurology.

3. 1.) Individual – Action, Perception, Cognition 2.) Task – Stability, Mobility , Manipulation 3.) Environment – Regulatory, Nonregulatory Movement emerges from Three Factors

4. A theory of motor control is a group of abstract ideas about the control of movement. A theory is a set interconnected statements that describe unobservable structures or processes & relate them to each other & to observable events . THEORY OF MOTOR CONTROL

5. Stimulus applied to muscle results in stereotypical responses referred to as a   reflex  (peripherally based) -afferent sensory inputs are necessary pre- requisite for efferent motor output . REFLEXES THEORIES

6. It is the Integrative action of the Nervous System. Sherrington   found that   reflexes   must be regarded as integrated activities of the total organism, not as the result of the activities of isolated “ reflex  arcs,” a notion that was currently accepted . building blocks of complex behaviors or movements. He believed that complex behaviors could be occur through combined action of individual reflexes that were chained together. Charles Sherrington

7. Actions performed automatically in response to a stimulus without conscious thought or decision are called reflex actions or reflexes . Simple reflex actions are handled by the spinal cord without involvement of the brain. Other reflexes are carried out in various relay centers in the lower brain or brainstem , but no conscious thought is involved. REFLEXES

8. Reflexes are classified according to the degree of complexity of the neuron (nerve) organization within the reflex arcs. CLASSIFICATIONS ARE : MONOSYNAPTIC (OR MONOSEGMENTAL) ♥ reflexes , which involve only one segment of the central nervous system,   MULTISYNAPTIC (OR INTERSEGMENTAL) ♥ reflexes , which involve more than one segment of the central nervous system.

9. Reflex actions carried out by the spinal cord occur automatically, but at the same time as the reflex occurs, sometimes a signal is sent to the brain by a connecting interneuron. When this happens, a stimulus is processed by the spinal cord as an arc and a response is sent back to the periphery, but a signal is also sent to the brain for interpretation and additional reaction .

10. Ex. Knee jerk response (simple/spinal cord only)

11. Sneezing – one of the reflex centers in the medulla (involves brainstem activity only )

12. Hand on a hot stove /a fire – a simple reflex pulls the hand away (spinal cord arc only, no brain involvement) followed by a reaction due to an interneuron connection to the brain from the spinal cord.

13. The systems described above represent the simplest units of the nervous system and are called REFLEX ARCS . There are 5 parts to these : 1. Sensory receptor(s) is/are stimulated . 2. Sensory neuron(s ) - send(s ) message to the spinal cord . 3. Interneuron(s ) - in CNS transmit the message to one or more motor neurons. 4. Motor neurons - transmit the message to the effector . 5. Effector (muscle) is stimulated.

14. A process of the sensory neuron carrying the stimulus to the spinal cord and brain, and then the brain sending message to the motor neuron. REFLEX ARC

15. * LIMITATIONS OF REFLEX THEORY * Unable to explain 1. Spontaneous and Voluntary Movements Reflex can be considered basic unit of behavior as reflex must be activated by an outside agent. 2 . Movement can occur without a sensory stimulus 3. Fast Sequential Movements ex. Typing 4. A single stimulus can trigger various responses 5. Novel movements can be carried out.

16. : TYPES OF REFLEXES

17. STRETCH REFLEX The stretch reflex ( myotatic reflex) is a muscle contraction in response to stretching within the muscle. This reflex has the shortest latency of all spinal reflexes. It is a monosynaptic reflex that provides automatic regulation of skeletal muscle length. When a muscle lengthens, the muscle spindle is stretched and its nerve activity increases. This increases alpha motor neuron activity, causing the muscle fibers to contract and thus resist the stretching. A secondary set of neurons also causes the opposing muscle to relax. The reflex functions to maintain the muscle at a constant length .

18. TENDON REFLEX The Golgi tendon reflex is a normal component of the reflex arc of the peripheral nervous system. The tendon reflex operates as a feedback mechanism to control muscle tension by causing muscle relaxation before muscle force becomes so great that tendons might be torn . Although the tendon reflex is less sensitive than the stretch reflex, it can override the stretch reflex when tension is great, making you drop a very heavy weight, for example. Like the stretch reflex, the tendon reflex is ipsilateral . The sensory receptors for this reflex are called Golgi tendon receptors, and lie within a tendon near its junction with a muscle. In contrast to muscle spindles, which are sensitive to changes in muscle length, tendon organs detect and respond to changes in muscle tension that are caused by a passive stretch or muscular contraction .

19. THE FLEXOR & CROSSED EXTENSOR REFLEX The crossed extensor reflex is a withdrawal reflex. The reflex occurs when the flexors in the withdrawing limb contract and the extensors relax, while in the other limb, the opposite occurs. An example of this is when a person steps on a nail, the leg that is stepping on the nail pulls away, while the other leg takes the weight of the whole body . The crossed extensor reflex is contralateral, meaning the reflex occurs on the opposite side of the body from the stimulus. To produce this reflex, branches of the afferent nerve fibers cross from the stimulated side of the body to the contralateral side of the spinal cord. There, they synapse with interneurons, which in turn, excite or inhibit alpha motor neurons to the muscles of the contralateral limb.

20. : THANK YOU!