Special Topics Flashcards
Regulation of body temperature is mediated by:
Hypothalamus
Initiate heat generating mechanisms
Set-point Temperature
Initiate heat loss mechanisms
Detected Temperature
Shivering, Thyroid hormone production, decreased sweating, piloerection, skin vasoconstriction (alpha 1), brown fat in babies (beta 3)
Heat-generating Mechanisms
Sweating, skin vasodilation, decreased heat production
Heat-loss Mechanisms
What is the role of fat in terms of regulation of body temperature?
Insulator
What is the role of skin in terms of regulation of body temperature?
Radiator System (when cold: blood vessels constrict; when hot: blood vessels dilate)
Most of the body heat is lost through which way?
Radiation>Evaporation>Conduction of air>Conduction of objects
What is the pathophysiology of fever?
Pyrogens➡️Increases IL-1➡️Increases Prostaglandins➡️ Increases set-point temperature in Hypothalamus
Excessive sweating causing fainting
Heat Exhaustion
High temperature causing tissue damage & impaired responses
Heat stroke
High temperature secondary to the use of succinylcholine & halothane?
Malignant Hyperthermia
What is the basis for muscle endurance?
Glycogen levels in the body
What is the best diet for muscle glycogen recovery?
High carbohydrate diet
How long does it take to recover muscle glycogen?
2 days (high carbohydrate diet)
An increase in muscle strength is always due to what?
Increase in muscle size
Maximal breathing capacity
150-170L/min
Pulmonary ventilation during maximal exercise
100-110L/min
Difference (50L/min) is used to compensate for:
Exercise at high altitudeExercise under hot conditionsAbnormalities of the respiratory system
During most strenuous exercise, muscle blood flow increase up to?
20x
At maximal exercise, CO is at ? Of its maximum
90%
At maximal exercise, pulmonary ventilation is at ? Of its maximum
65%
At high altitude, oxygen molecules are farther apart so?
Decreases oxygenation
At high altitude, its most important effect is?
Decreased mental proficiency
High altitude: Coma and death at ? Feet
23,000 feet
High altitude: Twitching and seizures at ? Feet
18,000 feet
High altitude: Drowsiness, Lassitude, Mental & Muscle fatigue, Headache, Nausea, & Euphoria at ? Feet
12,000 feet
Mechanisms of Acclimatization to Low PO2: Respiratory rate increases by 5x
Increased Pulmonary Ventilation
Mechanisms of Acclimatization to Low PO2: Shift to the right of the O2-HgB dissociation curve
Polycythemia
Mechanisms of Acclimatization to Low PO2: Increased pulmonary capillary blood volume, Increased lung volume, Increased pulmonary arterial BP
Increased Diffusing Capacity of Oxygen
Mechanisms of Acclimatization to Low PO2: Cardiac Output increases by 30%
Increased vascularity of the Peripheral tissues
Mechanisms of Acclimatization to Low PO2: Increased cell mitochondria and cellular oxidative enzymes
Increased ability of cells to use Oxygen despite low PO2
Changes seen in natural acclimatization
Decreased body massIncreased chest sizeLarger hearts and lungsBetter O2 delivery (increased HgB, better O2 utilization)
Manifestations of Acute Mountain Sickness
Acute Pulmonary EdemaAcute Cerebral Edema
Manifestations of Chronic Mountain Sickness
Pulmonary VasoconstrictionRight-sided Heart Failure
Adaptations to Flight: Pilot pushed against seat, more dangerous, blood shunted to the lower extremities
Positive G
Adaptations to Flight: Pilot pushed against his seatbelt, less dangerous, blood shunted to the head
Negative G
Motion sickness, Translocation of fluids, Diminished physical activity
Acute effects in Space
Decreased blood volume, Decreased RBC, Decreased muscle strength, Decreased maximum cardiac output, Loss of calcium and phosphate from bones
Chronic effects in Space
May lead to toxicities from high nitrogen, oxygen and carbon dioxide pressures
Diving
High Nitrogen Pressures: “Raptures of the depths”
Beyond 250 feet
High Nitrogen Pressures: Drowsiness
At 200-250 feet
High Nitrogen Pressures: Joviality
At 120 feet
Breathing oxygen at 4atm (PO2=3040mmHg) will cause sudden brain seizures followed by coma; Due to Oxygen Free Radicals (O2 and H2O2)
High Oxygen Pressure
Happens only if diving apparatus has a malfunction; Severe respiratory acidosis, lethargy, narcosis
High Carbon Dioxide Pressure
Sudden ascent a can lead to formation of nitrogen bubbles a blocks blood vessels
Decompression Sickness
Pain in the joints and muscles
“Bends”
Dyspnea
“Chokes”
Chronic Decompression Sickness
Caisson’s Disease
