Pathophysiology Daily Quizzes for Exam 4
Fluid and Electrolyte Balance:
Because they have more water, who is most likely to experience dehydration? Infants. They are about 75% water, as opposed to adults whichare 62-55% water.
You are losing more water than you are taking in. What type of balance are you in?  Negative balance.
What hormone is the most critical to maintaining water balance? Antidiuretic hormone. If this is not produced, the distal convoluted tubules and collecting ducts cannot absorb water, and it is lost in the urine regardless of how much sodium is reabsorbed.
Which one of the following in a cation? Cl^-, Ca⁺⁺, C₆H₁₂O₆   Calcium, it forms a positively charged ion when dissolved in water.
When a cell is placed in a hypotonic solution it will...take in water, swell and possibly burst.
What influences the osmolarity of a solution? The number of particles in that solution.
How does blood pressure or hydrostatic pressure influence water movement? The physical force (pressure) of the solution will cause water to leave the blood vessels and enter the tissues. In inflammation, the vessels dilate, which increases the blood flow to an area. This, plus the leakiness of the capillaries moves fluid into the tissues.
The sodium (and water) retaining hormone is... aldosterone.
The sodium (and water) losing hormone is... atrial natriuretic peptide - ANP.
What common hormonal imbalance causes osmotic diuresis? Diabetes mellitis - the high amount of glucose in the urine draws water after it resulting in polyuria, and also polydipsia to compensate.
What would be the result if a person was secreting too much aldosterone? hypernatremia  and hypokalemia - too much sodium and too little potassium - remember sodium and potassium are linked in the kidney.
 You are dealing with a patient that is experiencing hyperactive neuromuscular reflexes and tetany. What electrolyte imbalance does he have? Hypocalcemia.
Massive cellular trauma would result in...hyperkalemia. Remember that there is a lot of potassium inside the cells which is released abruptly with cellular damage.

Acids and Bases:
A solution with a pH of 3 would be considered acidic, and would have a high concentration of hydrogen ions.
A patient with a blood pH of 7.25 would be considered to be in a state of  acidosis.
The fastest means of controlling pH within the body is through...the use of buffer systems where we substitute a weak acid for a strong acid. The weak acids breaks up only partially, releasing fewer hydrogen ions and changing the pH much less than a strong acid (or base).
What is the most effective means of controlling acids within the body ? Renal mechanisms. If the kidney fails, pH balance fails. The kidneys can excrete acids and get them out of the body while conserving base. The kidneys can also manufacture bicarb when it is needed.
You have a patient that is in a state of acidosis. What electrolyte imbalance should you be watching for ? You should be watching for changes in the levels of potassium. Initially blood potassium levels will go up as the excess hydrogen ion diffuses into the cells, forcing the potassium out to maintain the balance of electrical charges inside the cell. The excess potassium will be excreted by the kidneys over time. Then, if the acid/base balance is corrected, the potassium in the blood will be taken back into the cells, and will result in hypokalemia.
A patient has the following lab results: pH= 7.6      HCO₃^- = 30 mEq/liter          pCO₂ = 44 mm Hg
The normal range of HCO₃^- is 22 to 26 mEq/liter
The normal range of pCO₂ is 35 to 45 mm Hg.
What is his problem?  From the pH value you should be able to recognize the condition as alkalosis. The only value that is outside the normal range is the bicarbonate, which is too high - bicarbonate excess - this is the definition of metabolic alkalosis.
Is the patient compensating? No. The carbon dioxide levels are in the normal range. However, remember how difficult it is to compensate for a metabolic alkalosis - the person has to decrease their respirations low enough to allow the build up of carbon dioxide to lower the pH. This would probably also result in hypoxia, which is not a good thing.
What could you do to help? Administer electrolytes to replace those lost. (If we are seeing hyperactive reflexes and tetany, what has the patient lost?) Administer I.V. chloride solution to maintain the balance of charges within the body (replacing bicarb ions).

Musculoskeletal review:
What bone cell lays bone down? The osteoblast
The cell that breaks bone down is the osteoclast and is derived from the fusion of monocytes.
What substance gives bone its flexibility? Collagen - this protein acts like rebar in a concrete building, allowing the bone to bend with out cracking.
How could you tell if someone was still growing? Take an x-ray of the long bones. If the epiphyseal plate is still visible, the person is still growing. If the plate has closed, and only the epiphyseal line is visible, the individual is done growing.
What neurotransmitter is always used at the neuromuscular junction?  Acetylcholine.

Musculoskeletal Pathophysiology :
Osteogenesis imperfecta is caused by a defect in collagen synthesis.  Inheritance is by  dominant and recessive genes, as well as new mutation.
The common name for this disease is brittle bone disease.
What would you expect to see in a severe case that survived birth?  Stunting of growth, incomplete ossification, and other skeletal defects, such as scoliosis. (If this affects respiration, what might you also expect?) You may also see blue sclera, defective tooth formation and faulty hearing.
How would achondroplasia affect bone growth? Most bones in the body are formed from a model made of hyaline cartilage through a process known as endochondral ossification. The articular cartilages and epiphyseal plates are remnants of this original cartilage model. Long bones, such as the humerus and femur, grow in length by ossifying cartilage at the epiphyseal plates. If there is a defect in the production of cartilage, the plates will close early, resulting in a person with a normal sized head and torso, but shortened arms and legs.
True or False: Two "little people" will always produce short offspring and two normal sized people with never produce a "little person." False. This trait has a dominant inheritance, so a person with the gene will normally express it, but even if two little people produce offspring there is a one in four chance that their child will be normal. Also, because this disease can arise through new mutation, it can occur in a child born to two normal parents.
What is the most common disease affecting the bones? Osteoporosis.
Who is affected more by this condition, men or women? Why? Women are most often affected and are affected sooner than men because of their lower starting bone density: They have less bone to lose, so problems show up sooner.
What is the major risk with osteoporosis? The risk of bone fractures.
What spinal deformity is caused by osteoporosis? Kyphosis- an increase in the thoracic curvature of the spine caused by the collapse of the vertebrae.
What does the World Health Organization use to define the disease? Bone density. Is this the only factor involved? No, also the microarchitecture of the bone as well.
What causes rickets and osteomalacia?  These diseases are caused by inadequate mineral deposition in a normal organic matrix. The result is softened bone that is subject to malformation and distortion, causing pain.
How are they different from each other? Rickets is due to a vitamin D deficiency in infants and children. Osteomalacia is rarely due to a vitamin D deficiency (except in cases where the patient is institutionalized and/or poorly cared for) but is more often due to an absorption problem, or renal or liver disease (organs that activate vitamin D).
Can osteoporosis and osteomalacia affect the same individual at the same time? Yes, and they intensify the effects of the other.
What causes osteoarthritis? This is classified as a degenerative joint disease; there is only a minimal inflammatory component. It is caused mostly by "wear and tear" on the joints and tends to affect the articular cartilage and causes a hardening or sclerosis, of the bone beneath the cartilage. Bone spurs or osteophytes may also form and enlarge the joint and cause pain and limit mobility.
What causes rheumatoid arthritis? This is a systemic inflammatory disease with involvement of the joints. It is usually an autoimmune disease that causes chronic inflammation of the connective tissues, primarily in the joints, but can also affect the heart, lungs, kidneys and skin and decrease life expectancy. Like osteoporosis, it affects more women than men, and shows the seasonal variations typical of autoimmune disfunctions.
What is Duchenne muscular dystrophy? This form of muscular dystrophy is due to a deficiency in a muscle protein called dystrophin which plays an essential role  in maintaining the structural integrity of muscle cells and may help to regulate the activity of muscle proteins. When the affected cells contract there is damage and tearing of muscle fibers. The damaged muscle is repair through fibrosis, or scar formation, which contracts and can distort the developing skeleton.
Which gender is most often affected by Duchenne muscular dystrophy and why?  This is an X linked recessive defect that affects males almost without exception. Most cases arise as a new mutation in families without a history of the disorder.  The gene is located on the short arm of the X chromosome, and is one of the largest genes ever found in the human.
How can it be diagnosed? Through high levels of creatine kinase, which is an enzyme released from damaged muscle fibers.
What is myasthenia gravis? Myesthenia gravis is an autoimmune disease in which  antibodies attack acetylcholine receptors at the neuromuscular junction. The loss of receptors causes muscle weakness and fatigability.
What are the symptoms of myasthenia?
In most cases we see pathological changes in what organ? There are pathologic changes or tumors in the thymus in up to 80% of the people with this condition.
How do we test for myasthenia gravis? Administer edrophonium chloride (Telison). The symptoms will improve for several minutes, but this is not long lasting enough to be used as a treatment.