Lab 8 Integration and Control EXERCISE Tisuis Study E amine a microscope slide c

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Lab 8 Integration and Control EXERCISE Tisuis Study E amine a microscope slide containing skeletesl mikei striations and Examine a microscope slide containing skeletal musele tissue. You darker striations and should be able to distinguish long fibers with alternate bands of lighter and multiple nuclei. On your Data Sheet, sketch several fibers and label the parts. Be sure your cells are large enough and eontain enough detail to be easily identified 2. NERVE CELLS: Examine a microscope slide containing neurons. How would you s appearance (long, short, globular, fibrous, etc.)? Can you distinguish the axons from the dendri tes? On your Data Sheet, sketch several neurons and label the parts. Be sure your are large enough and contain enough detail to be easily identified 3, NERVE CROSS SECTION: Examine a microscope slide containing a nerve cross section Does the interior of the nerve appear solid or is it packed with smaller units? You should be able to see that each neuron fiber has a wrapping around it. Sketch a low power view of the nerve cross section and a high power view of several neurons with the surrounding sheaths. EXERCISE 2 Reflexes A reflex is an automatic, coordinated reaction of an animal to a stimulus. You will observe several types of reflexes and diagram the pathway of the nerve impulse for one of them. Answer questions on the lab sheets provided. I. Knee-jerk (patella ligament) reflex--This is the most famous test used clinically to determine the excitability of the nervous system Have a partner sit on a high stool or table so that the lower legs hang freely. With the edge of your hand, strike the patellar ligament (located just below the patella or knee-cap and just above the tibial tuberosity). Observe the slight kicking motion. It may take a little practice to find the right spot to strike. This reflex involves only two neurons (a monosynaptic reflex). What types of neurons would they be? Where do they synapse? On your lab sheet, draw a simple diagram showing the route taken by the nerve impulse. 2. Swallowing Reflex-Allow a sip of water to come into contact with the back of your Stongue. What happens? Can you voluntarily prevent swallowing? 3. Pupillary Reflex-In a darker area of the lab, notice the size of your partner's pupil then shine a light into the eyes and notice the change in the pupil size. Shine the light into the right eye and notice the effect on the pupil of the left eye. 4 Accommodation Reflex-Have your partner look at something far away (100 meters or more). Hold a pencil about 50 centimeters in front of your partner and watch your partner's pupils. Have your partner now quickly look at the pencil. What happened to the pupils? EXERCISE 3 Sensitivity 1. To determine just how sensitive an area of the body is we can us a two point discrimination test. Use a pair is scissors to get two points that can be lightly touched to an are 93

Explanation / Answer

Answers to Exercise 2

1. During Knee Jerk the reflex involves two neurons with a monosynaptic reflex. These two neurons are Sensory Neuron and Motor neuron. Sensory neuron synapses the information to the motor neuron which carries the information.

Sensory neuron and Motor neuron in case of Knee Jerk synapse at the Spinal Cord.

2. When a sip of water comes in contact with the tongue then the tongue pushes the water into the back of the throat through the pharynx.

Swallowing can be prevented voluntarily only during the first phase which is known as the Oral phase. During Oral phase the food is chewed and mixed with saliva and later is pushed through the throat into the esophagus. During this oral phase we can voluntarily prevent swallowing.

3. In a darker room the size of the pupil gets bigger(dilates) in order to allow more light to enter. If we shine a bright light into the eyes then suddenly the size of the pupil gets smaller(constricts) in order to limit the amount of ligh to enter.

If we shine the light into the right eye then the pupil of both eyes left and right will get smaller that is both pupils constrict.

4. When the partner looks at the distant object then the size of the pupils is dilated that is bigger. But when the partner looks at the pencil quickly then both the pupils get smaller that is they constrict.

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