The Reflex Arc Reflexrapid predictable and involuntary response

The Reflex Arc § Reflex—rapid, predictable, and involuntary response to a stimulus § Occurs over pathways called reflex arcs § Occur without the use of the brain § Brain is usually “advised” that the reflex has occurred (Sometimes resulting in a secondary response- OUCH, which occurs after the reflex) Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord (c) Figure

Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord Sensory (afferent) neuron (c) Figure 7. 11 c, step 2 Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord Sensory (afferent) neuron Interneuron (c) Figure 7. 11 c, step 3 Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord Sensory (afferent) neuron Interneuron Motor (efferent) neuron (c) Figure 7. 11 c, step 4 a Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord Sensory (afferent) neuron Interneuron Motor (efferent) neuron Effector (biceps brachii muscle) (c) Figure 7. 11 c, step 4 b Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

2 Types of Reflexes and Regulation 1. Somatic reflexes § Activation of skeletal muscles Examples: Gag Reflex This reflex helps to prevent choking. Withdrawal Reflex Sharp, sudden pain causes the affected arm or leg to be withdrawn. Scratch Reflex An irritant to the skin causes scratching movement to relieve the itch. Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

2. Autonomic reflexes § Smooth muscle regulation § Heart and blood pressure regulation § Regulation of glands § Digestive system regulation § Saliva § Sweating § Pupil dilation § For more examples see next slide Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings