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3) Mammalian Physiology > Case Studies > Flashcards

Case Studies Flashcards

1
Q

What symptoms are present in cystic fibrosis (CF)?

A
  • Chronic cough
  • Diarrhea
  • Wheezing, respiratory issues
  • Runny nose
  • Salty skin
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2
Q

What is CF characterized by?

A

Defective epithelial ion transport

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3
Q

What are the secretory consequences of having CF?

A
  • Thick, viscous secretions in the lungs, pancreas, liver, intestine and reproductive tract
  • Increased salt content in sweat gland secretions
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4
Q

Where is the faulty CF gene located?

A
  • Chromosome 7

- Autosomal recessive

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5
Q

What chance is there that an offspring of carriers of CF develops CF?

A

25%

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6
Q

What chance is there that an offspring of carriers of CF does not develop CF?

A

75%

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7
Q

What does the CF gene code for?

A

CF transmembrane conductance regulator (CFTR)

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8
Q

What is the consequence of defective CFTR?

A
  • Defective cAMP-activated chloride and sodium channel that is present on the surface of many epithelial cells
  • NaCl becomes trapped in the cell, which pulls water in and dehydrates mucus
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9
Q

What is the mutation in the CF gene?

A
  • The amino acid phenylalanine in position 508 is missing (delta F508)
  • Three letter codon is missing
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10
Q

What are the underlying molecular mechanisms of CF?

A
  1. Mutated CFTR gene (gene is transcribed in the nucleus)
  2. Abnormal mRNA sequence (mRNA exits the nucleus) and binds to ribosome on RER (translation)
  3. Protein goes to the Golgi where it is processed or targeted for destruction
  4. Either no channel or faulty channel that does not allow NaCl out of the cell
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11
Q

70-80% of patients with CF lack what?

A

The receptor

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12
Q

What homeostasis is altered in CF?

A

Na+ and Cl- intracellular concentrations increase drastically

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13
Q

What causes salty skin in CF?

A
  • When CF is missing, chloride ions are not reabsorbed

- As sweat rises in the cell in the CFTR duct, cells do not reclaim the NaCl

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14
Q

What are the accepted treatments for children and adults with CF?

A
  • Airway clearance therapy
  • Antibiotics
  • Bronchial dilators
  • Vitamin supplements
  • Enzymes to aid digestion
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15
Q

What is happening in cancer cells that explains the large size of their nucleus and the relatively small amount of cytoplasm?

A

Actively dividing cells (such as cancer cells) are duplicating the amount of DNA within their nucleus, which explains why it is larger (as it takes more room)

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16
Q

What are symptoms of Tay-Sachs disease?

A
  • Slow loss of muscle control and brain function
  • Accumulation of gangliosides (loss of hexoaminidase A enzyme)
  • Vision problems or blindness
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17
Q

Why might the genetic test for mutations in the Tay-Sachs gene be more accurate than the test that detects decreased amounts of hexosaminidase A?

A
  • Hexosaminidase A detection is an INDIRECT measurement

- The genetic test is a DIRECT measurement

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18
Q

Is CFTR a chemically-gated, a voltage-gated, or a mechanically-gated channel protein?

A

Chemically-gated since it binds to ATP, allowing the channel to open and transport Cl- out of epithelial cells and into the lumen

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19
Q

Why would failure to transport NaCl into the airways cause the secreted mucous to be thick?

A
  • If NaCl is secreted into the lumen of the airways, water moves into the lumen as well, which thins the mucous
  • If NaCl cannot be secreted into the lumen, there will be no fluid movement to thin the mucous
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20
Q

Is CFTR protein on the apical or basolateral surface of the sweat gland epithelium?

A

The epithelial surface that faces the lumen of the sweat gland is the APICAL membrane

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21
Q

Why would an individual with cystic fibrosis require pancreatic enzymes to be taken whenever they eat?

A

Because the thick mucus in the pancreatic ducts block the secretion of digestive enzymes into the intestine

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22
Q

In which type of diabetes is the signal pathway for insulin more likely to be defective?

A

Type 2 diabetes

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23
Q

In which form of diabetes are the insulin receptors more likely to be up-regulated?

A
  • In type 1 diabetes, insulin is not secreted by the pancreas
  • Type 1 is therefore more likely to cause up-regulation of the insulin receptors
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24
Q

In the insulin reflex pathway, name the stimulus, sensor, integrating center, output signal, target, and response.

A
  • Stimulus: increase glucose concentration in the blood
  • Sensor: beta cells of the pancreas
  • Integrating center: beta cells
  • Output signal: insulin
  • Target: any tissues of the body that responds to insulin
  • Response: decrease in blood glucose
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25
Q

Why can’t glucose simply leak into cells when the blood glucose concentration is higher than the intracellular glucose concentration?

A

Because glucose is lipophobic; must enter through facilitated diffusion

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26
Q

What happens to the rate of insulin secretion when blood glucose levels fall? What kind of feedback loop is operating?

A
  • A decrease in blood glucose decreases insulin release

- Negative feedback loop

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27
Q

To which of the three classes of hormones do the thyroid hormones belong?

A

Amino-acid derivatives (tyrosine + iodine)

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28
Q

If a person’s diet is low in iodine, predict what happens to thyroxine production.

A

A person is unable to make thyroid hormones

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29
Q

In a normal person, when thyroid hormone levels in the blood increase, will negative feedback increase or decrease the secretion of TSH?

A

Decrease the secretion of TSH

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30
Q

In a person with a hyperactive gland that is producing too much thyroid hormone, would you expect the level of TSH to be higher or lower than in a normal person?

A

Lower (strong negative feedback)

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31
Q

Why is radioactive iodine (rather than some other radioactive element, such as cobalt) used to destroy thyroid tissue?

A
  • Radioactive iodine is concentrated in the thyroid gland, and therefore selectively destroy the tissue
  • Other radioactive elements distribute more widely throughout the body and may harm normal tissues
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32
Q

If levels of TSH are low and thyroxine levels are high, is Grave’s disease a primary disorder or a secondary disorder (one that arises as a result of a problem with the anterior pituitary)? Explain your answer.

A
  • In secondary hypersecretion disorders, you would expect the levels of the trophic hormones to be ELEVATED (which is not the case)
  • The oversecretion of thyroid hormones is NOT the result of elevated TSH
  • Grave’s disease is a primary disorder that is caused by a problem in the thyroid gland itself
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33
Q

Antibodies are proteins that bind to the TSH receptor. From that information, what can you conclude about the cellular location of the TSH receptor?

A

The TSH receptor is a membrane receptor, as antibodies (proteins) cannot cross the cell membrane

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34
Q

In Graves’ disease, why doesn’t negative feedback shut off thyroid hormone production before it becomes excessive?

A
  • Negative feedback is capable of shutting off endogenous TSH production
  • But, it fails to respond to the thyroid gland’s production of hormones as a result of the binding of antibody to the TSH receptor
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35
Q

What is Guillain-Barré syndrome? When does it appear?

A
  • Relatively rare paralytic condition
  • Strikes after a viral infection or an immunization
  • Lost sensation returns slowly as the body repairs itself
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36
Q

What division(s) of the nervous system may be involved in Guillain-Barré syndrome?

A
  • Problems with both afferent and efferent motor neurons

- Or, problems with the CNS integrating center

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37
Q

In GBS, what would you expect the results of a nerve conduction test to be?

A
  • In GBS, myelin around neurons is destroyed

- Decreased conduction speed or blocked conduction

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38
Q

What is AMAN? What might it be triggered by?

A
  • Acute motor axonal polyneuropathy (AMAN)

- Triggered by a bacterial infection

39
Q

How is AMAN initiated?

A

Damage of axons at neuromuscular junctions, the synapses between somatic motor neurons and skeletal muscles

40
Q

Name diseases involving altered synaptic transmission.

A
  • Parkinson’s disease
  • Depression
  • Schizophrenia
41
Q

What is the periodic paralysis disorder caused by?

A

Na+ or Ca2+ ion channel mutations in the membranes of the skeletal muscle fibers

42
Q

What effect would continued movement of Na+ have on the membrane potential of muscle fibers?

A

The influx of positive charge depolarizes the muscle, and it remains depolarized

43
Q

What is hypokalemic periodic paralysis characterized by?

A

Decreased blood levels of K+ during paralytic episodes

44
Q

What is hyperkalemic periodic paralysis (hyperKPP) characterized by?

A

Either normal or increased blood levels of K+ during episodes

45
Q

What ion is responsible for the repolarization phase of the muscle action potential, and in which direction does this ion move across the muscle fiber membrane? How might this be linked to hyperKPP?

A
  • K+ leaves the cell during repolarization

- The movement of K+ from the muscle fiber could contribute to elevated extracellular K+

46
Q

In people with hyperKPP, when do attacks occur?

A

After a period of exercise (i.e., after a period of repeated muscle contractions

47
Q

What are the characteristics of hyperkalemic periodic paralyses?

A
  • Only last a few minutes to a few hours
  • Generally involve only the muscles of the extremities
  • Muscles become weak and unable to contract (flaccid paralysis)
48
Q

What drugs may prevent hyperkalemic flaccid paralyses?

A

Diuretics, which increase the rate at which the body excretes water and ions (including Na+ and K+)

49
Q

Why does an Na+ channel that does not inactive result in a muscle that cannot contract (flaccid paralysis)?

A

If the muscle fiber is unable to repolarize, it cannot fire additional action potentials

50
Q

Why does oral glucose help individuals with hyperkalemic flaccid paralysis?

A
  • Glucose stimulates insulin release, and insulin increases Na+-K+-ATPase activity
  • Removes Na+ from the cells and helps them repolarize
51
Q

What is a heart attack?

A

Area of the heart that is dying because of a lack of blood supply (myocardial infarction)

52
Q

Why would oxygen and nitroglycerin help during a myocardial infarction?

A
  • Administration of oxygen increases O2 that reaches the heart and the brain
  • Nitroglycerin is metabolized to nitric oxide, which dilates blood vessels and improves blood flow
53
Q

What effect would the injection of isotonic saline have on an individual undergoing a heart attack? On their intracellular fluid volume? On their total body osmolarity?

A
  • The extracellular volume increases

- The intracellular volume and total body osmolarity does not change

54
Q

What are the effects of tissue plasminogen activator (t-PA) during a myocardial infarction?

A
  • Activates plasminogen
  • Dissolves blood clots that are blocking blood flow to the heart muscle
  • Helps limit the extent of ischemic damage
55
Q

What enzymes or other substances may serve as a marker for a heart attack?

A
  • Cardiac creatine kinase (CK-MB)

- Troponin I (TnI)

56
Q

Why would elevated blood levels of troponin indicate heart damage?

A

If troponin escapes from the cell and enters the blood, this is an indication that the cell either has been damaged or is dead

57
Q

What happens to contraction in a myocardial contracile cell if a wave of depolarization passing through the heart bypasses it?

A
  • It will not contract

- Failure to contract creates a non-functioning region of heart muscle and impairs the pumping function of the heart

58
Q

What is the function of beta blockers (B1-adrenergic receptors) following a heart attack? What does it cause to an individual’s heart rate?

A
  • Decreases heart rate and lowers oxygen demand, which decreases chances of cells dying
  • Antagonist to the B1-adrenergic receptors, which function to increase the heart rate
59
Q

What are common symptoms of myasthenia gravis?

A
  • Blurred vision
  • Drooping eyelids
  • Muscle weakness
60
Q

What are the results of a conduction test and an electromyography test in individuals with mysthenia gravis?

A
  • Conduction velocity is fine
  • Muscle response decreased QUICKLY during repeated nerve stimulation
  • Indicates that muscle response fatigued over time
61
Q

What is the cause of myasthenia gravis?

A
  • Autoimmune disease
  • Antibodies block or destroy Ach receptors at the neuromuscular junction
  • Prevents nerve impulses from triggering muscle contractions
62
Q

How is end-plate potential influenced in myasthenia gravis?

A

Declines in amplitude as the disease progresses, until the nerves no longer produce an AP

63
Q

What are treatment options for individuals with myasthenia gravis?

A
  • The removal of the thyroid gland

- Neostigmine (acetylcholinesterase inhibitor) allows a greater amount of Ach to accumulate in the synaptic space

64
Q

What are possible symptoms that may arise from a tumor near the pituitary?

A
  • Abnormal growth
  • Joint swelling and the presence of sores
  • Underweight
65
Q

Why would joint damage be associated with rapid growth and low testosterone levels?

A
  • Testosterone is involved in the hardening of bones during growth
  • Damage to the joints is related to low cortisol
66
Q

What is the Eric’s primary problem? What are secondary problems?

A
  • Pituitary gland has issues (primary)
  • Thyroid gland isn’t working (secondary)
  • Testes didn’t mature (secondary)
67
Q

Why would Eric be infertile?

A
  • Because he is taking replacement end-level hormones (testosterone)
  • Spermatogenesis requires FSH
68
Q

What may potentially be able to solve Eric’s infertility?

A

hCG, which acts as LH to attempt to initiate spermatogenesis

69
Q

What is acromegaly?

A

Joints continue to grow due to the increase in growth hormone in adulthood

70
Q

Why does Eric urinate so often at night?

A

Because he does not make enough ADH, causing diabetes insipidus

71
Q

Can you live without a pituitary?

A
  • Yes, if you get replacement pituitary hormones (FSH, LH)

- Yes, if you get replacement end-stage hormones (thyroid, testosterone)

72
Q

What are signs and symptoms of Grave’s disease?

A
  • Fast heartbeat
  • Poor tolerance of heat
  • Diarrhea
  • Unintentional weight loss
  • EYE BULGING
  • Enlarged thyroid
73
Q

With blood doping, would you expect a hematocrit value to be lower or higher than normal?

A

Higher hematocrit to increase oxygen-carrying capacity

74
Q

What is the molecular cause of sickle cell anemia?

A
  • Glutamate is replaced by valine

- Results in abnormal hemoglobin that crystallizes when it gives up oxygen

75
Q

How does sickle cell anemia result in tissue damage and pain from hypoxia?

A
  • Sickled cells become tangled with other sickled cells as they pass through smallest blood vessels
  • The blockage creates tissue damage and pain from hypoxia
76
Q

What is a treatment for sickle-cell anemia?

A
  • Administration of hydroxyurea
  • Compound that inhibits DNA synthesis
  • Alters bone marrow function so that immature blood cells produce the fetal form of hemoglobin, instead of adult hemoglobin
77
Q

What are hallmarks of a recent blood transfusion?

A
  • Elevated hemoglobin

- Elevated hematocrit

78
Q

How might an individual, who has undergone blood doping, reduce his hematocrit without removing red blood cells?

A
  • By drinking fluids, he would increase his plasma volume quickly
  • If plasma volume increases, hematocrit will decrease even if RBC volume does not change
79
Q

One hallmark of illegal EPO use is elevated reticulocytes in the blood. Why would this suggest greater-than-normal EPO activity?

A
  • Reticulocytes are the final immature stage of RBC development
  • If RBC development is more rapid, more reticulocytes may be released into the blood before they have time to mature
80
Q

What occurs physiologically in a cleft palate?

A
  • Palatine bones fail to unite completely
  • Only partially separate the nose and mouth
  • Produces difficulty in swallowing and speech
81
Q

What are the causes of cleft palates?

A
  • Genetic: mutant gene (trisomy 13)

- Non-genetic: teratogenics (corticosteroids, benzodiazepines, and anticonvulsants)

82
Q

Cleft palates result from a developmental defect due to decreased _________________.

A

migration of neural crest cells

83
Q

What may be used to correct cleft palates?

A

Bone graft

84
Q

How may you reduce the changes of cleft palates?

A

By taking a multivitamin with folic acid (48% reduction)

85
Q

What is chronic obstructive pulmonary disease?

A
  • Air exchange is impaired by narrowing of the lower airways

- Most people with COPD have emphysema or chronic bronchitis, or both

86
Q

What do patients with chronic bronchitis ressemble?

A
  • “Blue bloaters”
  • Bluish tinged skin (low blood O2 levels)
  • Tendency to be overweight
87
Q

What do patients with emphysema ressemble?

A
  • “Pink puffers”
  • Thin, have normal (pink) skin coloration
  • Often breathe through pursed lips, which helps open their airway
88
Q

What causes recurrent lung infections in cystic fibrosis?

A
  • There is no solute movement from the ECF to the lumen
  • Cilia become trapped in thick, sticky mucus and can no longer move
  • Mucus cannot be cleared, and bacteria colonize the airways
89
Q

Why do people with chronic bronchitis have a higher-than-normal rate of respiratory infections?

A

Bacteria trapped in the mucus can multiply and cause respiratory infections

90
Q

What occurs in a pneumothorax?

A
  • If the sealed pleural cavity is opened to the atmosphere, air flows in
  • The bond holding the lung to the chest wall is broken, and the lung collapses, creating a pneumothorax (air in the thorax)
91
Q

A victim has been stabbed in his left lung. Why does the left side of his rib cage seem larger than the right side?

A
  • Loss of adhesion between the lung and chest wall would release the inward pressure exerted on the chest wall
  • The rib cage would expand outward
92
Q

Name the muscles that patients with emphysema use to exhale actively.

A
  • Internal intercostal muscles

- Abdominal muscles

93
Q

Why would an individual with emphysema have an increased RBC count and hematocrit?

A
  • Her arterial partial pressure of oxygen is low
  • The major stimulus for RBC synthesis is hypoxia
  • Triggers EPO release

3) Mammalian Physiology (24 decks)

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