Translational Physiology Block 8 Flashcards Preview

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Flashcards in Translational Physiology Block 8 Deck (21):

How can someone reverse obesity and diabetes?

Roux en Y bypass; pharmacotherapy, and lifestyle modifications (diet and exercise)


What gene is involved in muscle growth and remodeling? negative regulator of muscle mass?

Fn14; myostatin


Describe euglycemic-hyperinsulinemic clamp.

The amount of glucose needed to maintain euglycemia provides a measure of insulin-mediated glucose uptake, or insulin resistance.


T/F: healthy aging is associated with a decline in glucose tolerance and insulin sensitivity?



When does aging (senescence) begin?



Define homeostenosis.

Older persons have limited physiologic reserves with which to maintain the internal physiologic milieu


What is frailty?

is a pathologic syndrome that results in a constellation of signs and symptoms, and is characterized by high susceptibility, impending decline in physical function and high risk of death.


Describe heat stroke.

Excessive cutaneous vasodilation can lead to a fall in arterial pressure and therefore to a decrease in brain perfusion

High body temperature can cause fibrinolysis and consumption of clotting factors and thus disseminated intravascular coagulation

Heat-induced damage to the cell membranes of skeletal and myocardial muscle leads to rhabdomyolysis (in which disrupted muscle cells release their intracellular contents, including myoglobin, into the circulation) and myocardial necrosis.

Cell damage may also cause acute hepatic insufficiency and pancreatitis

Renal function, already compromised by low renal blood flow, may be further disrupted by the high plasma levels of myoglobin


Describe training regimens for diabetic patients.

Goal of exercise in treating diabetic patients is not to improve maximal oxygen uptake but rather to improve insulin sensitivity (GLUT4 translocation)

Requires a training regimen that limits muscle stress and TNF alpha


What is frailty?

is a pathologic syndrome that results in a constellation of signs and symptoms, and is characterized by high susceptibility, impending decline in physical function and high risk of death.

anorexia, sarcopenia, immobility, atherosclerosis, balance impairment, depression, cognitive impairment

"loss of functional reserve"

3/5 criteria: unintentional weight loss, muscle weakness, slow walking speed, exhaustion, and low physical activity

etiology: other disease and/or aging


Describe acclimatization to altitude.

adaptive processes of acclimatization reduce, as much as possible, the size of each step in the oxygen cascade (the process of declining oxygen tension from atmosphere to mitochondria; throughout the cascade oxygen is either extracted or lost) resulting in a final partial pressure (mixed-venous blood) at high altitude that is not greatly different from the sea level value (HYPERVENTILATION)

After 20 days, at altitude, sea level values of alveolar carbon dioxide partial pressure produce a massive increase in ventilation (hypercapnic ventilatory response)


What happens in conditions of mild hypoxia?

Exposure to even mild hypoxia stimulates the peripheral chemoreceptors (increase in carotid sinus nerve)

No change in minute ventilation up to an altitude of around 3000 meters

hypoxia increases cerebral blood flow and decreases cerebral extracellular partial pressure of carbon dioxide, which increases the pH around the central medullary chemoreceptors causing them to exert an equal and opposite inhibitory effect opposing any increase in ventilation


What is the result of respiratory alkalosis?

Respiratory alkalosis stimulate production of 2,3-diphosphoglycerate shifting the oxygen-hemoglobin dissociation curve to the right (affinity for hemoglobin for oxygen is decreased)


How is diffusion capacity change at high altitude?

At extreme altitude, even at rest, marked diffusion limitation occurs because of the feeble oxygen partial pressure gradient which does not permit equilibration of oxygen between the alveoli and capillary in the time that it takes for a red cell to traverse the alveolar capillary (also occurs with exercise at altitude)


T/F: Exposure to hypobaric hypoxia produces pulmonary vasoconstriction resulting in pulmonary hypertension



What happens to fluid content of the body with altitude?

Plasma volume is reduced on exposure to altitudes of between 3500 and 4000 meters (persists for months)

decreased AVP (less necessity for thirst)

urine output remains the same

aldosterone release decreased (renin elevated)


Why does average diameter of muscle shrink at altitude?

May reduce the distance that oxygen has to diffuse from the capillaries to the mitochondria

Muscle myoglobin appears to be increased at altitude improving oxygen diffusion through muscle cells and perhaps acting as an oxygen reservoir during periods of profound cellular hypoxia


What increase maximal oxygen consumption?

Barometric pressure, ventilation, diffusing capacity, cardiac output, hematocrit


What is termed acclimation in space flight? acclimatization?

hours to days; days to months


Which muscle fibers experience the greatest loss during space flight?

type 2; phenotypic shift from type 1 to type 2 (results in more fatigue)


Why might immune system be impaired during space flight?

Increased circulating levels of glucocorticoids and catecholamines may mediate changes in the immune system