Case Study 1 - The Female Body Case Study 1 Hematology AIDS An...

Interactive Case Studies and the Human Body (1-10) The Female Body

Case Study 1 Hematology AIDS

Answers:

• This individual has Acquired Immunodeficiency Syndrome (AIDS) caused by the

Human Immunodeficiency Virus (HIV).

• 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.

• The individual is experiencing hypokalemia prior to treatment.
• This abnormal potassium level could cause cardiac arrhythmias due to the

hyperpolarization of the resting membrane potential.

Case Study 2 Gastrointestinal Hiatal Hernia

Answers:

• The disorder is a hiatal hernia. This is a structural defect in which a weakened

diaphragm allows a portion of the stomach to pass through the esophageal diaphragmatic opening into the chest when intra-abdominal pressure increases.

• Adequate lower esophageal pressure at the lower esophageal sphincter normally

prevents gastric reflux into the esophagus when lying down or bending over.

• The parasympathetic division of the autonomic nervous system (cholinergic)

innervates the lower esophageal sphincter (LES). Therefore, cholinergic agonists would increase LES contraction, preventing gastric reflux. Anticholinergic agents would decrease LES pressure.

• Histamine (H2) antagonists are recommended because they reduce gastric

acidity by selectively blocking the H2 receptors (which mediate gastric secretion).

• Elevation of the head of the bed is recommended to encourage gravitational flow

of the gastric contents toward the pyloric end of the stomach.

• The normal pH of the esophagus is 6-7.

The normal pH of the stomach is 2-5.(Anatomy & Physiology An Integrative Approach, 4e Michael McKinley, Valerie O'Loughlin, Theresa Bidle) (Solution Manual, For Complete File, Download link at the end of this File) 1 / 3

The lower esophageal pH for this individual may be approximately 3-5. The stomach pH would not change (pH = 2-5).

Case Study 3 Reproductive Endometriosis

Answers:

• This condition is known as endometriosis.
• It may be caused by (a) a retrograde flow of menstrual tissue back through the

uterine (fallopian) tubes, (b) an in situ formation from hormonally induced metaplasia, or (c) a combination of transport of tissue and metaplastic changes.

• Ectopic endometrial tissue is endometrial tissue occurring in a place other than

the uterus, such as the abdominal cavity or uterine tubes.

• Danazol, a gonadotropin inhibitor, blocks Gn-RH output to decrease FSH and LH

output, thus decreasing circulating estrogen and progesterone. This will prevent endometrial growth, vascularization, and menses, and allow the aberrant endometrial implants to regress.

• Oral contraceptives could also be used as a treatment since they too can

suppress ovarian luteal function and decrease circulating estrogen and progesterone.

Case Study 4 Muscle Physiology Heat Cramps

Answers:

• 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.

• Carpopedal spasms are spasmodic contractions of the muscles of the hands and

feet.

• Salt and water ingestion is beneficial because NaCl and water have been lost

during profuse sweating. Therefore, hypovolemia (decreased circulating body 2 / 3

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 Study 5 Muscle Physiology Neuromuscular Blocking Agents (for Surgery)

Answers:

• 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.

• ACh is hydrolyzed by the enzyme acetylcholinesterase (AChE), which is on the

postsynaptic membrane, with its active site facing the synaptic cleft.

• 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.)

• / 3