homeothermy book notes

homeothermy book notes - Stress Adaptation Homeorhesis...

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Stress, Adaptation, Homeorhesis, Pathogenesis Physiologic Comfort Zone - can take an value within the comfort zone without compensatory reactions---if moves out of comfort zone- those reactions then come into play Stressed- When physiological variables are greatly disturbed—and much greater effort required to set it right Animals divert resources so corrective mechanisms receive priority---- growth, fiber production, reproduction, egg-laying, lactation will all be compromised until stress taken care of Fight of Flight —Profound activation of the sympathetic nervous system--- responses include: increasing breathing, elevated HR, elevated BP, redistribution of blood flow from cutaneous and visceral tissues to favor perfusion of skeletal muscle Also, sympathetic discharge— medullary hormones, provokes hyperglycemia due to mobilization of hepatic glycogen reserves Hypothalamo-Pituitary Adrenal Cortex Axis —is activated and the resulting hypercortisolism prevails for duration of stress--- cortisol favor hyperglycemia—gluconeogenesis and antagonization of glucose utilization is many tissues Adaptation— With sustained stress—make adjustments to variety of physiologic systems Increased appetite is an adaptation to increased energy expenditure as a result of pregnancy and lactation---they would otherwise cause negative energy balance Homeorhesis - form of physiological regulation that permits major alterations in how animals expend metabolic resources Chronic hypertension can be a result of homeostatic regulators of arterial blood pressure are functioning, but the set-points and comfort range for pressure are chronically adjusted upward.---comfort range widened in some situations thereby reducing requirement for rigid control Thermoregulatory Mechanism Heat production part of catabolism ---oxidation of glucose to carbon dioxide, water, and energy in ATP still results in 50% energy lost as heat Heat Exchanges—heat loss Sensible —occurs when thermal energy directly transferred through physical processes of radiation, convection, and conduction Radiation —causes both heat gain and loss---transfer by electromagnetic waves without heating the space between the emitter and absorber Warming effect of the sun Radiant heat losses or gains are: 1. proportional to temperature raised to the forth power. 2. proportional to available surface area, and
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This note was uploaded on 03/26/2008 for the course AN SC 150 taught by Professor Butler,wr during the Spring '06 term at Cornell.

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homeothermy book notes - Stress Adaptation Homeorhesis...

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