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this is an anatomy question

You walk out of a dark movie theater into bright sunlight. Yourpupils constrict, you squint your eyes and raise your arm to shieldyour face.

what are the neural pathways taken to do each thing? (pupilsconstrict, squint, move arm)

where do these signals go in the brain? where are the neuronssynapsing?

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Patrina Schowalter
Patrina SchowalterLv2
28 Sep 2019
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Related questions

Jim, A 19-year-old college student, was rock climbing when he fell 30 feet to the ground. Paramedics arriving at the scene found him lying in the supine position, unable to move any extremities and complaining of neck pain. He was awake, alert, and oriented to his current location, the date and day of the week, and the details of his fall. His responses to questioning were appropriate. He complained that he could not feel his arms and legs. His pupils were equal and reactive to light. He showed no other signs of injury except for several scrapes on his arms. His vital signs revealed a blood pressure of 110 / 72, heart rate of 82 beats per minute, respirations of 18 per minute. The paramedics applied a cervical collar, placed him on a back board, immobilized his head, and transported him to the trauma center by helicopter. Upon examination at the hospital, Jim had minimal biceps brachii stretch reflexes, but no triceps or wrist extensor reflexes. All other muscle stretch reflexes in the upper and lower extremities were absent. His perception of sensory stimuli ended bilaterally at an imaginary line drawn across his chest about 3 inches above the nipples (i.e. everything below felt numb). He had some sensation in his arms, but could not localize touch or describe texture with any consistency there. He was able to raise his shoulders and tighten his biceps brachii slightly in each arm, but could not raise either arm against gravity. His lower extremities were flaccid, despite attempts to move them. Vital signs were taken again at the hospital and were as follows: blood pressure=94 / 55; heart rate=64; respiratory rate=24 (with shallow breathing). X-rays taken upon arrival revealed a fractured vertebra at a particular location. A chest X-ray showed a decreased lung expansion upon inhalation. The neurosurgeons immobilized his neck by inserting tongs into the skull above the ears to hold his neck in a position so that no further injury could occur. Jim was transferred to intensive care and his condition was stabilized. A physical examination four days later revealed normal vital signs and no change in his arm strength or sensation, but also marked spasms and exaggerated stretch reflexes of the lower extremities. He also had urinary incontinence which required the placement of a Foley catheter connected to a urine collection bag.

Questions:

1. Why did Jim's heart rate and blood pressure fall in this time of emergency (i.e. at a time when you'd expect just the opposite homeostatic responses)?

2. Upon admission to the hospital, Jim's breathing was rapid and shallow. Can you explain why?

3. Why did he lose some sensation in his arms and all sensation from the upper trunk down?

4. What is the primary muscle of respiration? Which spinal nerves contribute to innervate this muscle? (It’s almost like this question is review…)

5. Based upon the physical exam findings, which vertebral bone do you think was fractured? Give reasons for your answer. (Life’s anatomy knowledge is cumulative…)

6. By four days after the injury, some of Jim's signs and symptoms had changed. His arm muscles were still flaccid, yet his leg muscles had become spastic and exhibited exaggerated stretch reflexes. How would you explain these findings?

Answer question part a-d

Question part A

Diffusion Lab

Purpose: To investigate the diffusion of a substance across a semipermeable membrane.

Materials:

iodine (must be colored, clear won't work)

cornstarch/water solution

plastic sandwich bags (cheap is good)

beakers or clear plastic cups

Set-Up and Procedure
1. Fill beaker about halfway and put about ten drops of iodine.
2. Put about a teaspoon of starch and about 3 ounces of water in baggie and tie.
3. Make sure that it is water tight
4. Put the baggie in the beaker or glass and wait.
5. In about 15 minutes the solution in the baggie will turn blue/black. (purple)
This is a result of the iodine diffusing through the bag.
You should know that iodine is an indicator for starch. It turns blue/black in color.
Test it by dropping some iodine on a piece of white paper.

Questions and Conclusions :

Define permeability

To which substance is the plastic bag is permeable ?

Why did the iodine enter the bag ?

Why didn't the starch enter the beaker?

How is the plastic bag like the cell membrane?

Question part b

Reflex Lab

Procedures for Reflex Lab

In this lab we will test muscle stretch reflexes and cutaneous reflexes.

A partner is needed to be the subject for this lab.

Purpose: To test and observe normal muscle stretch and cutaneous reflexes.

Equipment: Reflex hammer,

Background: In the most narrow sense, a reflex is an involuntary, unpremeditated response by the body to an external stimulus. Reflexes allow reaction to a stimulus more quickly than would be possible if conscious thought were involved. A reflex can be described as a stimulus-response cycle. Most reflexes involve the brainstem or the spinal cord and do not require interaction from higher brain centers. The muscle stretch reflexes are the simplest reflexes. They involve the sensory neuron synapsing directly upon the motor neuron. They are sometimes called monosynaptic reflexes. They are also called spinal reflexes because the reflexive action does not require input from the brain. The other reflexes we will be testing in this lab are the cutaneous reflexes. They are also called superficial reflexes because the receptors are in the superficial areas of the body. They are more complex and require the message to go up the spinal cord to the brain and then back down to elicit the response. These can be used to test for CNS injury.

There are five components to a reflex; these components together are called the reflex arc. The components are as follows:

sensory receptor – receives the stimulus and generates an impulse (is usually a nerve ending)

afferent pathway – a neuron that carries the impulse from the receptor to a central integrating center

integrating center –this is where the afferent component connects to the efferent component- this is in the CNS. One or more synapses must occur here. Interneurons are not involved in stretch reflexes but are always found in all other types of reflexes.

efferent pathway - a neuron that carries the impulse from the integrating center to an effector.

effector -receives the impulse and responds. The effector may by skeletal muscle, smooth muscle, or glands.

For more information please read chapter 12 : "Muscle" ( Pages 380-390) in Human Physiology book ( 12th edition by Stuart Ira Fox)

Part I. Stretch reflexes.

First do muscle stretch reflexes which are also called deep tendon reflexes.

It is important the subject relax the muscle being tested. Tell the subject to let the muscle go limp.

Rate each response according to the following scale:

+4 very brisk, hyperactive, large movement at joint.

+3 brisker than average, medium movement at joint

+2 average, small movement at joint

+1 somewhat diminished, very small or no movement at joint

0 no response

A. Patellar (also called the knee jerk reflex) – activation of femoral nerve. The receptor is located in the quadriceps muscle, the effector is the quadriceps muscle. The nerve ending is responding to the stretch of the muscle caused by striking the tendon.

1. A subject is allowed to sit comfortably on a table with knees dangling over the edge.

2. Using a reflex hammer (or substitute as described above) strike the patellar tendon just below the kneecap.

3. Observe the action caused by the reflex.

4. Record your results using the graded scale above.

B. Biceps Reflex – activation of the musculocutaneous nerve

1. Rest subject’s left forearm along your left forearm.

2. Subject’s hand should rest in or near the bend of your elbow.

3. Press your left thumb on the subject’s biceps tendon, apply a little pressure.

4. Strike your thumb with the reflex hammer, this will transfer the pressure to the biceps tendon.

5. Watch carefully for twitching of the biceps muscle. Usually, the forearm will not move.

6. Record your results using the graded scale above.

C. Triceps reflex – activation of the radial nerve.

This is a difficult reflex to observe, but give it a try.

1. The subject should have the arm relaxed and elbow bent.

2. Support the entire weight of the arm with your left hand.

3. Strike the triceps tendons, just above the elbow.

4. Watch carefully for twitching of the biceps muscle.

5. Record your results using the graded scale above.

Both B and C show up best on someone who doesn’t have a lot of subcutaneous fat and who has good muscle definition.

D. Achilles reflex (also called ankle-jerk reflex) – activation of the poplitealnerve. The principle is similar to the knee-jerk reflex. Here the stretch receptors are located in the gastrocnemius muscle.

1. Have the subject take her/his shoes and socks off, exposing the Achilles tendon on the back of the ankle.

2. Strike the Achilles with the reflex hammer (or substitute) and observe the extension of the foot downward.

3. Record the results using the graded scale above.

Part II. Cutaneous reflexes

A. Plantar reflex

This reflex differs from the four muscle stretch reflexes. In this reflex, receptors are stimulated in the sole of the foot (cutaneous receptors). The reflex pathway travels up the leg to the integrating center. While in the integrating center, the reflex travels up the spinal cord through the pyramidal tracts, which are nerve pathways between the spinal cord and brain.

1. The subject needs to lie on his or her back, with shoes and socks off.

2. Using the end of the handle of the reflex hammer, trace a path along the lateral side from heel to the little toe to the big toe.

3. Observe for the flexion (toe curling) which is recorded as a normal plantar reflex.

4. If the toes curl, this is called a Negative Babinski response and is normal. If the toes flare, then an abnormal response is recorded and is called a Positive Babinski response and indicates CNS damage.

5. Record the results.

B. Ciliospinal reflex – This reflexive pathway is from the skin to the thoracic spinal cord, through the sympathetic trunk, then to the dilator pupillae muscle of the eye. This is another test of the CNS.

1. Pinch the back of the subject’s neck,

2. Watch pupils for a response.

3. A normal response is dilation of the pupil.

4. Record your results.

question part c

Homeostasis Lab - Heart Beat Regulation


This lab is designed to help explore the process of homeostasis as it applies to regulating heart rate. It also should help how a sampling process works.

Make two copies of the data sheet (or make your own) and paste them into your report.

1. Take a pulse for six seconds, record this number in the table below.

2. Every 15 seconds for the next three minutes, take a pulse again for six seconds, record each of these values.

3. Multiply each of these values by 10 to get the beats per minute.

4. Now average these numbers (this is the setpoint for the pulse at resting). Note the range of values (that is how far they can deviate from the set point).

5. The next step is to take a 30 second reading. Multiply this number by 2 to get beats per minute.

6. How does this compare to the setpoint?

7. Repeat steps 1 through 6 after running in place for 30 seconds. Record the same data.

8. After getting 8 readings, stop and plot these numbers on a piece of graph paper. The X-axis should be minutes and the Y-axis should be heart rate.(Don't forget to connect the points ). You can do this in Excel and then import it into Word. Or you can e-mail this to me.

Submit your lab report in the correct format.. Respond to the questions above. Explain WHY the results were what they were. Compare the resting and post-exercise and postulate explanations for the differences. You should have two data tables and one graph with your heart rate data from both tables on it in your report.

Time in seconds

Heart rate (bpm)

0 (initial recording)

15

30

45

60

75

90

105

question part d

What was one thing you found interesting, confusing or surprising about any of the lab activities? Why?

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