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mb2005 mb2005
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Posts: 13
13 years ago
Need some assistance with these. No need to post activity 5 because its already here.
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Staff Member
13 years ago
Activity 2: Determining the Effect of Thyroxine on Metabolic Rate (p. 47)

7. On the normal rat, the metabolic rate after thyroxine injection is faster than the baseline
metabolic rate.
The action of thyroxine is to increase the metabolic rate of all cells.
On the thyroidectomized rat, the metabolic rate after thyroxine injection is faster than
the baseline metabolic rate.
The injected thyroxine compensated for the thyroxine lost when the thyroid was removed.
On the hypophysectomized rat, the metabolic rate after thyroxine injection is faster than
the baseline metabolic rate.
The injected thyroxine compensated for the thyroxine lost when the pituitary gland was
removed. The pituitary gland did not produce TSH, therefore the thyroid gland did not
produce thyroxine.

Activity 3: Determining the Effect of TSH on Metabolic Rate (pp. 47–48)

7. On the normal rat, the metabolic rate after TSH injection is faster than the baseline
metabolic rate.
The TSH increased production of thyroxine.
On the thyroidectomized rat, the metabolic rate after TSH injection is the same as the
baseline metabolic rate.
Since there is no thyroid gland in the thyroidectomized rat, the injected TSH had nothing
to act upon. There was no organ to receive the pituitary TSH and produce thyroxine,
On the hypophysectomized rat, the metabolic rate after TSH injection is faster than the
baseline metabolic rate.
The injected TSH compensated for the TSH lost when the pituitary gland was removed,
and spurs production of thyroxine.

Activity 4: Determining the Effect of Propylthiouracil
on Metabolic Rate (p. 48)

7. On the normal rat, the metabolic rate after propylthiouracil injection is slower than the
baseline metabolic rate.
Propylthiouracil is antagonistic to thyroxine and will tend to decrease the effects of
thyroxine.
On the thyroidectomized rat, the metabolic rate after propylthiouracil injection is the
same as the baseline metabolic rate.
Since the thyroidectomized rat cannot make any thyroxine, the propylthiouracil has
nothing to be antagonistic to and therefore has no effect.
On the hypophysectomized rat, the metabolic rate after propylthiouracil injection is the
same as the baseline metabolic rate.

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- Master of Science in Biology
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mb2005 Author
wrote...
13 years ago
okay.
wrote...
Donated
13 years ago
Activity 1: Electrical Stimulation (pp. PEx-39–40)
2. At 1.0 V, there is no response—the screen displays a flat line.
The threshold voltage is at 3.0 V.
4. The slight increase in voltage results in a slight increase in the height of the action potential peak.
At threshold voltage, the smaller fibers in a nerve are stimulated and an action potential is seen.
Increasing the voltage will cause most, if not all, of the neural fibers to undergo depolarization. A given
nerve is made up of literally thousands of neuron processes (axons), so this slight increase is noted when
all fibers in the nerve fire.
5. The maximal voltage is 4.0 V.

Activity 2: Mechanical Stimulation (pp. PEx-40–41)
2. An action potential is generated when you touch the rod to the nerve.
The tracing is identical to the tracing generated at the threshold voltage.

Activity 3: Thermal Stimulation (p. PEx-41)
An action potential is generated when you touch the heated rod to the nerve.
The tracing shows the action potential peaking slightly higher than the peak generated by the unheated rod.
Thermal stimulation can also elicit a nerve response. Heat generates action potentials in more of the neurons in a nerve than
are generated by touch.

Activity 4: Chemical Stimulation (p. PEx-41)
1. Yes, dropping sodium chloride on the nerve generates an action potential.
2. No, the tracing does not differ from the original threshold stimulus tracing.
4. Yes, dropping hydrochloric acid on the nerve generates an action potential.
No, the tracing does not differ from the original threshold stimulus tracing.
6. Electrical, mechnical, thermal, and chemical stimulation are all capable of generating an action potential
in a nerve.

Inhibiting a Nerve Response
Activity 5: Testing the Effects of Ether (pp. PEx-42–43)
2. The screen displays a flat line, indicating no nerve response.
The nerve has been anesthesized by the ether.
4. The nerve begins to respond to electrical stimuli again after about 6 minutes.

Activity 6: Testing the Effects of Curare (p. PEx-43)
2. There is no change to the action potential tracing.
Nerve propagation is unaffected because curare works on the synaptic ends of the nerve.
Curare would ultimately kill the organism by blocking nerve transmission.

Activity 7: Testing the Effects of Lidocaine (p. PEx-43)
1. No.
2. At threshold voltage, the screen still displays a flat line.
Lidocaine is a sodium ion channel antagonist which will block sodium channels from opening, thus
inhibiting any action potential from being generated.

Nerve Conduction Velocity
Activity 8: Measuring Nerve Conduction Velocity (pp. PEx-44–46)
5. 5 volts

(COULDNT COPY CHART CORRECTLY HERE, SORRY)

11. The earthworm has the slowest conduction velocity.
The speed of the earthworm nerve was about 8.85 m/sec.
Rat nerve 2 had the fastest conduction velocity.
The speed of rat nerve 2 was about 46.74 m/sec.
The larger the nerve, the faster the conduction velocity.
Conduction velocity is faster if the nerve is myelinated than if it is not.
In myelinated nerves, conduction velocity is faster as the action potential jumps from node of Ranvier
(internode) to node of Ranvier and does not travel along the cell membrane.
wrote...
Donated
13 years ago
Suppose someone will have to delete that; It appears I posted the wrong exercise because the lab manual physioEx exercises are numbered differently. I have posted the answers for the Neurophysiology of Nerve Impulses Lab. Neutral Face
mb2005 Author
wrote...
13 years ago
Exercise 4
Activity 1:  Determining the Baseline Metabolic Rates
Activity 2:  Determining the Effect of Thyroxine on Metabolic Rate
Activity 3:  Determining the Effect of TSH on Metabolic Rate
Activity 4:  Determining the Effect of Propylthiouracil on Metabolic Rate
Activity 5:  Hormone Replacement Therapy
Activity 7:  Measuring Fasting Plasma Glucose
Activity 8:  Measuring Cortisol and Adrenocorticotropic Hormone
wrote...
Donated
13 years ago
Hormone Replacement Therapy
Activity 5: Hormone Replacement Therapy (pp. PEx-55–56)
9. Student answers will vary.
12. T score (control): –2.7 ± 0.15
15. T score (estrogen): –2.0 ± 0.15
16. T score (calcitonin): –2.6 ± 0.15
17. Estrogen injections changed the rat’s T score from the osteoporosis range to the osteopenia range.
The calcitonin injections had little to no effect on the rat.
Insulin and Diabetes

Activity 7: Measuring Fasting Plasma Glucose (pp. PEx-58–61)
20. Sample 1: glucose concentration of 95–105 mg/deciliter
23. Sample 2: glucose concentration of 110–120 mg/deciliter
Sample 3: glucose concentration of 126–136 mg/deciliter
Sample 4: glucose concentration of 115–125 mg/deciliter
Sample 5: glucose concentration of 135–145 mg/deciliter

Patient 1’s glucose reading was in the normal range.
Patient 3’s and Patient 5’s glucose readings were in the diabetic range.
Patient 2’s and 4’s glucose readings were in the impaired fasting glucose range.
A special diet would be recommended where simple sugars are restricted.
The diagnosis would be gestational diabetes. A special diet would be recommended where simple sugars
are restricted.

Activity 8: Measuring Cortisol and Adrenocorticotropic Hormone (pp. PEx-61–63)
17. Patient 1: cortisol 3 ± 1 mcg/dL Low ACTH 18 ± 2 pg/ml Low
Patient 2: cortisol 35 ± 5 mcg/dL High ACTH 13 ± 2 pg/ml Low
Patient 3: cortisol 45 ± 5 mcg/dL High ACTH 86 ± 5 pg/ml High
Patient 4: cortisol 3 ± 1 mcg/dL Low ACTH 100 ± 5 pg/ml High
Patient 5: cortisol 50 ± 5 mcg/dL High ACTH 18 ± 2 pg/ml Low
PhysioEx
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