Case Histories in Human Physiology

Answer Key

Third Edition

Donna Van Wynsberghe

University of Wisconsin-Milwaukee

Gregory M. Cooley

Radiation Oncology Associates, Mequon, Wisconsin

Printed for the exclusive use of the University of Wisconsin-Milwaukee summer session Anatomy & Physiology course. Further reproduction of this material is strictly forbidden.
Contents

Neurophysiology Case Histories 3

Case 1 Bell’s Palsy 3

Case 2 Multiple Sclerosis 3

Case 3 Sciatica 4

Case 4 Seizures (Epilepsy) 4

For Your Consideration: Neurology 4

Muscle Physiology Case Histories 5

Case 5 Muscular Dystrophy (Duchenne) 5

Case 6 Heat Cramps 5

Case 7 Neuromuscular Blocking Agents 5

For Your Consideration: Muscles 6

Hematology Case Histories 7

Case 8 Chronic Myelocytic Leukemia (CML) 7

Case 9 Iron Deficiency Anemia 7

Case 10 Polycythemia 8

Case 11 AIDS 8

For Your Consideration: Hematology 8

Cardiovascular Case Histories 9

Case 12 Angina Pectoris 9

Case 13 Mitral Incompetence 9

Case 14 Primary Hypertension 10

Case 15 Stroke 11

For Your Consideration: Cardiovascular 11

Respiratory Case Histories 12

Case 16 Asthma 12

Case 17 Emphysema 13

Case 18 Respiratory Muscle Paralysis 13

For Your Consideration: Respiration 14

Gastrointestinal Case Histories 15

Case 19 Hiatal Hernia 15

Case 20 Duodenal Ulcer 15

Case 21 Appendicitis 16

For Your Consideration: Gastrointestinal 16

Renal Case Histories 17

Case 22 Renal Failure 17

Case 23 Kidney Stones 17

Case 24 Dialysis 18

For Your Consideration: Renal 18

Endocrine Case Histories 19

Case 25 Diabetes Insipidus (DI) 19

Case 26 Primary Hypothyroidism 19

Case 27 Addison’s Disease (Primary Adrenocortical Insufficiency) 20

Case 28 Diabetes Mellitus 21

Case 29 Hypoparathyroidism/Hypocalcemia 22

For Your Consideration: Endocrine 22

Reproductive Case Histories 23

Case 30 Secondary Hypogonadism 23

Case 31 Endometriosis 23

Case 32 Pregnancy 23

Case 33 Breast Cancer 24

Case 34 Prostate Cancer 25

For Your Consideration: Reproduction 25

Neurophysiology Case Histories

Case 1 Bell’s Palsy

Answers:

1. The cranial nerve involved in this individual is the facial (VII) nerve.

2. This condition is known as Bell’s palsy.

3. This disorder results in blocked conduction of motor impulses along this cranial nerve, which innervates muscles of facial expression. (The conduction block may result from inflammation, hemorrhage, tumor, meningitis, or local traumatic injury around the nerve.) This motor impairment results in facial paralysis, inability to smile, and inability to close her left eye.

4. Her taste was distorted because there are also sensory fibers in this compressed cranial nerve originating from the taste buds on the anterior two-thirds of the tongue.

5. The major disorder of cranial nerve V (trigeminal) is trigeminal neuralgia (also known as tic douloureux), a painful disorder of one or more of the three major branches of the trigeminal nerve (ophthalmic, maxillary, mandibular). Trigeminal neuralgia is characterized by excruciating searing or burning pain that occurs in lightninglike jabs and lasts around one to two minutes in an area innervated by one or more branches of the trigeminal nerve.

6. Bell’s palsy is a disorder of the cranial nerve VII (facial) that produces unilateral facial weakness or paralysis.

7. Trigeminal (V): mixed nerve; the “great sensory nerve”; carries sensory information from the face from the three major branches (ophthalmic, maxillary, and mandibular). Motor fibers innervate the muscles of mastication.

8. Facial (VII): mixed nerve; the “great motor nerve”; motor fibers innervate the muscles of facial expression. Sensory fibers arise from taste buds on the anterior two-thirds of the tongue.

Case 2 Multiple Sclerosis

Answers:

1. The demyelinating disease affecting this individual is multiple sclerosis.

2. Myelin is a lipoprotein substance that forms a sheathlike covering around neurons. Myelin provides insulation for an axon and increases conduction velocity by only allowing action potentials to “leap” from node of Ranvier to node of Ranvier( i.e., saltatory conduction).

3. Because this disease is thought to have allergic and inflammatory causes, prednisone is used to reduce the associated edema of the myelin sheath during exacerbations (bouts).

4. Oligodendrocytes form myelin sheaths around the axons of the CNS. Schwann cells form myelin sheaths around axons of the PNS.

Case 3 Sciatica

Answers:

1. The disorder of this individual is a slipped (ruptured, herniated) disk resulting in sciatica.

2. The sciatic nerve is the major nerve involved. It leaves the spinal cord at L4–S3, and is part of the lumbosacral plexus.

3. A dermatome is an area of the skin innervated by all the cutaneous neurons of a certain spinal or cranial nerve. The dermatomes for this individual (L4–S3) involve the genitalia, gluteal region, posterior thigh, and leg region. (See your textbook for a dermatome diagram.)

4. These conditions cause peripheral nerve root compression from the intervertebral disk protrusion.

5. The compression was affecting both the dorsal (sensory) and ventral (motor) rootlets or was compressing the nerve root (which has both sensory and motor fibers).

6. Relieving muscle spasms with bed rest, local heat, oral analgesics, and oral muscle relaxants is the first form of treatment. Diathermy (deep heat) may also help reduce muscle spasms and pain. Steroidal anti-inflammatory agents may be beneficial in long-term control. Surgical removal of the intervertebral disk protrusion may eventually be necessary.

Case 4 Seizures (Epilepsy)

Answers:

1. This individual is experiencing seizures (epilepsy).

2. Seizures can be classified as: 1) partial (local) and 2) generalized. Simple partial seizures usually do not result in impairment of consciousness while generalized seizures do.

3. Ictal means pertaining to a sudden attack or seizure; interictal means occurring between seizures.

4. The skull X-ray and CT scan are performed to rule out pathologic causes (brain tumors, etc.) and skull fractures, including injuries to the brain.

FOR YOUR CONSIDERATION: NEUROLOGY

1. Anticonvulsants 4 Cerebrovascular insufficiency

2. Cholinergics 3 Mild, moderate, severe pain

3. Narcotic and opioid analgesics 2 Myasthenia gravis

4. Vasodilators 1 Seizures

Muscle Physiology Case Histories

Case 5 Muscular Dystrophy (Duchenne)

Answers:

1. This hereditary X-linked recessive disease characterized by progressive muscular weakness is Duchenne-type muscular dystrophy.

2. Dystrophy means defective nourishment. In muscular dystrophy there is death to muscle and replacement by fat and connective tissue, with concomitant metabolic defects.

3. Muscles involved in walking “on the toes” are the gastrocnemius and the soleus. The tibialis anterior muscles are “weakening,” failing to pull the toes up (opposing the gastrocnemius muscles).

4. The trunk muscles that weaken in certain cases of lordosis and abdominal protuberance are the following:
Lordosis: quadratus lumborum and iliocostalis lumborum
Abdominal protuberance: external oblique, internal oblique, transversus abdominis, and rectus abdominis

Case 6 Heat Cramps

Answers:

1. A cramp within a muscle is an involuntary, painful, and prolonged contraction. The precise cause of cramping is not known but is probably due to conditions within the muscle, such as altered calcium or oxygen levels, or to stimulation of the motor neurons.

2. Carpopedal spasms are spasmodic contractions of the muscles of the hands and feet.

3. Salt and water ingestion is beneficial because NaCl and water have been lost during profuse sweating. Therefore, hypovolemia (decreased circulating body fluid volume) is occurring. This is causing blood to be redistributed to the vital organs of the body (brain, heart, lungs) and directed away from exercising skeletal muscle. The skeletal muscle is therefore exposed to low oxygen and increased waste metabolites (lactic acid, etc.). This causes the severe cramping. Body fluids are isotonic to a 0.9% NaCl solution. Since NaCl and water have both been lost during sweating, replacement of both is essential to restore the blood volume back to normal. (In individuals who become unconscious during heat shock, intravenous infusions of 0.9% NaCl are administered.)

Case 7 Neuromuscular Blocking Agents (for Surgery)

Answers:

1. The depolarizing impulse releases acetylcholine (ACh) from the nerve ending, which diffuses across the neuromuscular junction. At the muscle membrane or motor end-plate, the ACh attaches to its specific receptor sites. The ionic channels (primarily sodium) open, allowing the ions to cross the membrane. If a sufficient quantity of the neurotransmitter is released and threshold is reached, action potentials will be elicited. This electrical activity will cause the release of calcium from the terminal cisternae. The calcium will interact with the contractile proteins (troponin) of the thin filaments, allowing tropomyosin to be moved away from the actin active sites so myosin heads can form cross-bridges with the binding sites on the actin proteins, resulting in sarcomere shortening and muscle contraction.

2. ACh is hydrolyzed by the enzyme acetylcholinesterase (AChE), which is on the postsynaptic membrane, with its active site facing the synaptic cleft.

3. Agents or drugs that block or compete for the ACh receptors themselves will prevent the normal interaction of the transmitter and the receptors, thus blocking muscle contraction and causing flaccid paralysis. (Curare competes with ACh for the receptor proteins on the muscle cell membrane, thus reducing the size of the end-plate potential. Thus, curare can be used as a muscle relaxant during anesthesia.)

FOR YOUR CONSIDERATION: MUSCLE

1. Corticosteroids 4 Muscle spasticity

2. Gold compounds 3 Osteoarthritis; bursitis

3. Nonsteroidal anti-inflammatory drugs (NSAIDS) 2 Rheumatoid arthritis (RA)

4. Skeletal muscle relaxants 1 Severe inflammation

Hematology Case Histories

Case 8 Chronic Myelocytic Leukemia (CML)

Answers:

1. The primary disorder of this person is chronic myelocytic leukemia (CML).

2. Leukocytosis is an increase in the number of white blood cells, characteristic of many infections and other disorders.

3. The cause of the leukocytosis (elevated leukocytes) is abnormal production and release of leukocytes from bone marrow, spleen, and lymph nodes.

4. Thrombocytopenia is a reduction in the number of platelets in the blood.

5. The cause of the thrombocytopenia (decreased platelet count) is the tightly packed bone marrow (from the leukocytosis), which inhibits the production of platelets.

6. Anemia is a blood condition in which the number of functional red blood cells or their hemoglobin content is below normal.

7. The cause of the anemia (decreased erythrocyte count) is the tightly packed bone marrow (from the leukocytosis), which inhibits the production of erythrocytes.

8. The feeling of abdominal fullness is caused by the enlarged spleen.

Case 9 Iron Deficiency Anemia

Answers:

1. The primary disorder of this individual is iron deficiency anemia.

2. Ferrous sulfate or ferrous gluconate provides a source of iron. This iron source is necessary in the bone marrow for hemoglobin production by developing erythrocytes.

3. Suggested dietary inclusions of foods rich in iron:

mg Iron/100 gm

Liver 8.8

Egg yolks 7.2

Cashews 3.8

Turkey 2.1

Chicken 1.8

Potatoes 1.1

Vegetables 1.0

4. A gynecologic examination is important (a) to determine if the amount of blood lost during the monthly menstrual cycle can be reduced, and (b) to help rule out other reasons for heavy blood loss.

5. Bone marrow iron is an important clinical indicator in this individual because it indicates a lack of the precursor, iron, at the site where erythrocytes are produced.

Case 10 Polycythemia

Answers:

1. The disorder of this individual is polycythemia.

2. The arterial O2 saturation and erythropoietin levels are important in confirming that the increased hematocrit is not due to hypoxemia or an abnormally elevated erythropoietin level. The O2 saturation level would indicate if there is a physiologic stimulus for the increased erythrocyte production.

3. Phlebotomy is the letting of blood for transfusion pheresis, diagnostic testing, or experimental procedures.

4. Phlebotomy (removal of the whole blood) removes both blood cells and plasma. The plasma volume is replaced within days, whereas the erythrocytes take several weeks to be replaced.

5. Myelosuppressive therapy is therapy for the suppression of the bone marrow’s production of blood cells and platelets.

6. Myelosuppressive therapy may be needed to suppress the erythrocyte production in the myeloid tissue if the hematocrit continues to rise after the phlebotomies.

Case 11 AIDS

Answers:

1. This individual has Acquired Immunodeficiency Syndrome (AIDS) caused by the Human Immunodeficiency Virus (HIV).

2. The hematocrit abnormality is caused by the dehydration.

3. Some current treatments include: AZT (Zidovudine) and ddI (Didanosine), both antiretroviral agents which slow the replication of the virus, prevent occurrence or recurrence of opportunistic infections, and boost the immune system.

4. The individual is experiencing hypokalemia prior to treatment.

5. This abnormal potassium level could cause cardiac arrhythmias due to the hyperpolarization of the resting membrane potential.

FOR YOUR CONSIDERATION: HEMATOLOGY

1. Anticoagulants 1 Emboli; deep vein thrombosis

2. Hematinics 3 Hemophilia

3. Hemostatics 4 Heparin overdose

4. Heparin antagonists 2 Iron deficiency anemia

5. Vitamins (B12) 5 Pernicious anemia

Cardiovascular Case Histories

Case 12 Angina Pectoris

Answers:

1. The term for the type of chest pain experienced by this individual in angina pectoris. The cause of this pain is myocardial ischemia (lack of blood flow to the heart muscle) and the resultant accumulation of metabolites from the hypoxia.

3. The site of action for each of the pharmacologic drug therapies follows:
Nitroglycerin: potent smooth-muscle relaxer and vasodilator, especially in the venous or capacitance system; it probably has little effect on the coronary blood vessels. It also lowers systolic pressure, thus reducing myocardial wall tension, a major determinant of myocardial oxygen need. Overall, this drug brings myocardial oxygen supply and demand into more favorable balance.
Beta-blockers: beta receptor blockers act on the heart to reduce cardiac workload.
Calcium channel blockers: act on the heart and vascular smooth muscle (especially arterial vessels, reducing spasms and promoting vasodilation) to reduce cardiac workload.

4. The right and left coronary arteries are paired branches off the ascending aorta. The right coronary artery branches into a marginal artery, which supplies blood to the right atrium and ventricle, and a posterior interventricular (descending) artery, which supplies blood to the right and left ventricles. The left coronary artery divides into a circumflex artery, which supplies blood to the left atrium and left ventricle, and an anterior interventricular (descending) artery, which supplies blood to the right and left ventricles.