Human Reflex Physiology Exercises

R E V I E W S H E E T EXERCISE 2 Human Reflex Physiology The Reflex Arc 1. The five components of a reflex are shown in the figure below. 2. In general, what is the importance of reflex testing in a routine physical examination? It allows the condition of the nervous system to be assessed. Somatic and Autonomic Reflexes 3. Use the key terms to complete the statements given below. (Some terms are used more than once.) Key: a. abdominal reflex d. corneal reflex g. patellar reflex b. calcaneal tendon reflex e. crossed-extensor reflex h. plantar reflex c. ciliospinal reflex f. gag reflex Reflexes classified as somatic reflexes include a Of these, the stretch reflexes are B  and   A  , i. pupillary light reflex B  ,  D , E  , G , and the superficial reflexes are Reflexes classified as autonomic reflexes include C  and I  . F  ,  G , and  A and    H  . H  . 4. One of the somatic spinal reflexes is Calcaneal tendon reflex. Name two other somatic spinal reflexes that are mediated at the spinal cord level. patellar reflex, and crossed-extensor reflex  5. One of the three somatic spinal reflexes in which the higher brain center participate is Abdominal. Name the other two. ------------------------------------------- cremaster, and plantar reflexes 6. Can the stretch reflex be elicited in a singly pithed animal (that is, an animal in which the brain has been destroyed but the spinal cord is still intact.)? Yes.  Explain your answer. It is a cord-mediated reflex, it is initiated and executed at the spinal cord level and the higher brain centers do not need to be intact for this to occur.  7. Trace the reflex arc, naming efferent and afferent nerves, receptors, effectors, and integration centers, for the two reflexes listed. (Hint: Remember which nerve innervates the anterior thigh, and which nerve innervates the posterior thigh.) patellar reflex: Proprioceptors (stretch receptors) in the quadriceps muscle → afferent fibers of femoral nerve → spinal cord → efferent fibers of femoral nerve → quadriceps muscle 9. Name the division of the autonomic nervous system responsible for each of the reflexes listed. ciliospinal reflex: sympathetic salivary reflex: parasympathetic  pupillary light reflex: parasympathetic  10. The pupillary light reflex, the crossed-extensor reflex, and the corneal reflex illustrate the purposeful nature of reflex activity. Describe the protective aspect of each. pupillary light reflex: Itprotectstheretinafromexcessiveillumination,whichisdamagingtothephotoreceptors.   corneal reflex: Itprotectstheeyefromtrauma.   crossed-extensor reflex: Itwithdrawstheinjuredlimbfromthepainfulstimuluswhilesimultaneouslyextendingthe oppositelimb.Iftheupperlimbsareinvolved,extensionoftheoppositelimbactstopushawaythestimulus.Ifthelower   limbsareinvolved,extensionoftheoppositelimbpreparesthelimbtoreceivethebodyweight.   11. Was the pupillary consensual response contralateral or ipsilateral? Contralateral  Why would such a response be of significant value in this particular reflex? Helps to even out the light rays making it less stressful for the affected eye. -----------------------------------12. Differentiate between the types of activities accomplished by somatic and autonomic reflexes.. Somatic includes all pathways that are voluntary, and autonomic includes all pathways that are involuntary actions      Reaction Time of Intrinsic and Learned Reflexes 14. How do intrinsic and learned reflexes differ? Basic reflexes are inherited - born with them. Learned/acquired reflexes are not inherited - not born with them. ------------------------------------------------------------------- 15. Name at least three factors that may modify reaction time to a stimulus. Illness, age, and fatigue.  16. In general, how did the response time for the learned activity performed in the laboratory compare to that for the simple patellar reflex? learned reflexes are not as fast as basic reflexes.  17. Did the response time without verbal stimuli decrease with practice? Yes.     Explain the reason for this. Because it is being leaned/stored by repetition. General Sensation Structure of General Sensory Receptors 1. Differentiate between interoceptors and exteroceptors relative to location and stimulus source. interoceptor: in viscera or deep in body tissues; internal stimuli  exteroceptor: at or close to the body surface; stimuli in external environment 2. The cutaneous receptors are labelled on the diagram below. 3. Match the general sensory receptors with their descriptions.  e    1. muscle spindle a. touch receptor located in the deepest layer of the epidermis  d    2. tactile corpuscle b. deep pressure receptor located in the dermis  a    3. epithelial tactile complex c. pain receptors  c    4. free nerve endings d. touch receptor located in the dermal papillae  b    5. lamellar corpuscles e. proprioceptor located in skeletal muscle Receptor Physiology 5. Explain how the two-point discrimination test illustrates how the density of touch receptors in a receptive field varies in different areas of the body. two point discrimination test tries to determine how far apart each receptive field is. On fingers, there are lots of pressure/touch receptors and the receptive fields are small because we can feel the two points when they're at close distances. other places, receptive fields are larger, and two-point distances are larger accordingly 6. Explain how the error of localization correlates to the size of the receptive field as demonstrated by the tactile localization experiment. having specific localization or found at certain discrete points the larger the size of the receptor field the larger the error of localization can be  7. Several questions regarding general sensation are posed below. Answer each by placing your response in the appropriately numbered blanks to the right. 1. Which cutaneous receptors are the most numerous? 2–3. Which two body areas tested were most sensitive to touch? 4–5. Which two body areas tested were least sensitive to touch? 1 pain receptors 2–3. Lips and fingertips 4–5. Ventral forearm and back of neck 6. Lumbar region  6–8. Where would referred pain appear if the following organs were receiving painful stimuli: (6) gallbladder, (7) kidneys, and (8) appendix? (Use your textbook if necessary.) 9. Where was referred pain felt when the elbow was immersed in ice water during the laboratory experiment? 10. What region of the cerebrum interprets the kind and intensity of stimuli that cause cutaneous sensations? 2 R E V I E W 7. Lumbar region 8. Lumbar region 9. Medial aspect of the hand 10. somatosensory association cortex  S H E E T EXERCISE NAME _____________________________ LAB TIME/DATE ____________________ Special Senses: Anatomy of the Visual System Anatomy of the Eye 1. Name five accessory eye structures that contribute to the formation of lacrimal fluid (tears) and/or help lubricate the eyeball, and then describe the major secretory product of each. 5 Accessory structures Product lacrimalglands Salinesolution Conjunctiva Mucus Tarsalglands oilysecretion Caruncle Whitishoilysecretion Ciliaryglands Sweat 4. Identify the extrinsic eye muscle predominantly responsible for each action described below.  Lateralrectus         1. turns the eye laterally  Medialrectus         2. turns the eye medially   Inferioroblique     3. turns the eye up and laterally  Inferiorrectus        4. turns the eye down and medially  Superiorrectus      5. turns the eye up and medially  Superioroblique   6. turns the eye down and laterally 5. What is a sty? inflammation of a small oil or sweat gland associated with the eye exterior  What is a Conjunctivitis? inflammation of the conjunctiva  6. Correctly identify each lettered structure in the diagram by writing the letter next to its name in the numbered list. Use an appropriate reference if necessary.  7. Match the key responses with the descriptive statements that follow. (Some choices will be used more than once). e. cornea j. retina b. choroid f. fovea centralis k. sclera c. ciliary body g. iris d. ciliary processes of the h. lens ciliary body i. optic disc Key: a. aqueous humor l. scleral venous sinus m. vitreous humor A_____________________ 1. fluid filling the anterior segment of the eye  k   2. the “white” of the eye   i     3. part of the retina that lacks photoreceptors   c     4. modification of the choroid that contains the ciliary muscle   l   5. drains aqueous humor from the eye   j     6. layer containing the rods and cones  m      7. substance occupying the posterior segment of the eyeball  b       8. forms the bulk of the heavily pigmented vascular layer ________c,g ,   9. composed of smooth muscle structures (2)   f   10. area of critical focusing and detailed color vision D     11. form (by filtration) the aqueous humor ________d,____________   12. light-bending media of the eye (4)  E,a,h,m    ,   e   13. anterior continuation of the sclera—your “window on the   k   world” 14. composed of tough, white, opaque, fibrous connective tissue Visual Pathways to the Brain 13. The visual pathway to the occipital lobe of the brain consists most simply of a chain of five cells. Beginning with the photoreceptor cell of the retina, name them, and note their location in the pathway. 1. Photoreceptor cell: Retina 2. Bipolar cell: retina 3 Ganglion cell: retina 4. Neuron: lateral geniculate nucleus of the thalamus 5. cortical neuron:primary visual cortex of the cerebral hemisphere