Interactive Case Studies and the Human Body (1-10)
The Female Body
Case Study 1
Hematology
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.
Case Study 2
Gastrointestinal
Hiatal Hernia
Answers:
1. 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.
2. Adequate lower esophageal pressure at the lower esophageal sphincter normally
prevents gastric reflux into the esophagus when lying down or bending over.
3. 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.
4. Histamine (H2) antagonists are recommended because they reduce gastric
acidity by selectively blocking the H2 receptors (which mediate gastric secretion).
5. Elevation of the head of the bed is recommended to encourage gravitational flow
of the gastric contents toward the pyloric end of the stomach.
6. The normal pH of the esophagus is 6-7.
The normal pH of the stomach is 2-5.
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:
1. A. This condition is known as endometriosis.
B. 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.
2. Ectopic endometrial tissue is endometrial tissue occurring in a place other than
the uterus, such as the abdominal cavity or uterine tubes.
3. 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.
4. 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:
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 Study 5
Muscle Physiology
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.)
Case Study 6
Hematology
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 Study 7
Respiratory
Asthma
Answers:
1. The disorder is asthma.
2. This is primarily an obstructive disorder as evidenced by the reduced
FEV1.0/FVC.
3. RV = TLC - VC.
4. RV before using the bronchodilator = 3.92 L.
RV after using the bronchodilator = 1.81 L.
(RV = TLC - VC. Normal RV = approximately 1.2 L.)
5. Expiration is more difficult than inspiration in this person because of the following
facts: Inspiration is an active process. Expiration is passive. Bronchoconstriction
increases expiratory difficulty by further narrowing of the airways, thus increasing
the work of expiration. Also, inspiration causes expansion of the airways during
the negative pressure breathing, whereas expiration leads to further narrowing of
the already narrowed airways.
6. The change in pulmonary function after the bronchodilator therapy indicates that
the airways were narrowed (bronchoconstriction) and relieved with bronchodilator
therapy-a reversible process.
7. The bronchodilator exaggerates the tachycardia because epinephrine is a
sympathomimetic agent (mimics the sympathetic nervous system) and therefore
increases heart rate.
8. The hypoxemia (PaO2 = 70) is due to the bronchoconstriction, increased RV, and
increased diffusion distance in the alveoli due to the mucus accumulation as
evidenced by the wheezing.
The hypocapnemia (PaCO2 = 26) is due to the increased frequency of breathing.
CO2 also diffuses between the blood and the alveoli (the alveolar-capillary
membrane) twenty times as fast as O2; therefore, CO2 is more easily removed
from the blood.
9. The beta2-adrenergic agent was prescribed due to its reduced cardiostimulatory
(beta1) effects based upon these facts: the heart has primarily beta1 receptors
on cardiac muscle and the sinoatrial node, whereas bronchial smooth muscle
has primarily beta2 receptors. A beta2-adrenergic agent causes relaxation of
bronchial smooth muscle (bronchodilation) with minimal cardiostimulatory effect.
(Epinephrine stimulates both beta1 and beta2 receptors.)
10. An anticholinergic agent might also help the breathing problem for the following
reasons: Bronchial smooth muscle is innervated by both the parasympathetic
(cholinergic) and sympathetic (adrenergic) divisions of the autonomic nervous
system. Parasympathetic innervation causes bronchoconstriction. An
anticholinergic agent would therefore cause bronchodilation.
Case Study 8
Endocrine
Diabetes Mellitus
Answers:
1. Noncompliant is the failure or refusal to comply (as in the taking of prescribed
medication).
2. This person is experiencing ketoacidosis as suggested by the acetone odor on
his breath due to elevated fatty acid metabolism. This indicates that there was
not enough insulin to allow the blood glucose to get into the cells, so the cells
shifted to their second preferred fuel (fats) for metabolism, thus dumping keto
acids, causing the acetone breath odor.
3. The serum bicarbonate is low due to the buffering of the keto acids by the
bicarbonate ions.
4. This is an example of metabolic acidosis.
5. Dyspnea is caused by the acidosis, which stimulates the respiratory center,
producing the rapid, deep respiration known as Kussmaul breathing (as
described by Kussmaul). Hypotension is caused by fluid loss from an osmotic
diuresis (glucose loss in the urine). Tachycardia is a reflex response in an
attempt to overcome the hypotension.
6. This person needs a rapid-acting insulin and IV fluids in the form of 0.9% sodium
chloride (plus bicarbonate if the blood pH is <7.1 and the serum bicarbonate is
<10 mEq/L). (There are approximately seven forms of insulin currently available
in the United States with different rates of onset, effectiveness, and duration of
action. They are generally classified into rapid-, intermediate-, and long-acting
insulins.)
Case Study 9
Renal
Renal Failure
Answers:
1. A. This individual has chronic renal failure (CRF). B. This is due possibly to an
obstruction of the ureters or of the renal arteries, or due to a kidney infection or
renal tumors.
2. Hyponatremia is a deficiency of sodium in the blood. Hyperkalemia is an excess
of potassium in the blood.
3. The hyponatremia may be caused by volume dilution. The hyperkalemia may be
caused by cellular breakdown or may be due to dietary sources of potassium
(meat, vegetables, fruit). There may also be tubular dysfunction, especially at the
aldosterone site of the distal tubule of the nephron.
4. The blood in the urine may be due to glomerular disease (altered porosity of the
glomerular membrane; damage to the glomerular tuft) or may occur from the
action of tubular enzymes that degrade red blood cells.
5. The renal function tests for this individual show marked reduction in the renal
blood flow (23% of normal) and marked reduction in GFR (33% of normal).
6. The "puffy" feeling is due to fluid retention from decreased RBF and GFR.
7. The cause of the chronic renal failure needs to be determined first and then
treated specifically. Meanwhile, dietary and fluid intake need to be monitored.
Reduced dietary protein (to reduce nitrogenous waste production) with sufficient
carbohydrate and fat to meet energy requirements and prevent ketosis or muscle
wasting is recommended. Water intake should be controlled to maintain a serum
sodium of 135-145 mEq/L. Sodium should be restricted or permitted, depending
on whether the individual is accumulating or losing sodium.
8. Fluid and dietary control may be adequate to support this individual through the
diagnosis and treatment. If not, intermittent dialysis may be necessary.
Case Study 10
Muscle Physiology
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