Thermoregulation Flashcards
Define thermoregulation and its importance
regulation of body temperature to maintain bodily function.
Inadequate homeostatic balance of temperature commonly results in death
What is the preoptic- anterior hypothalamus role
Body’s thermostat, increases or reduces heat production by activating various physiological mechanisms.
Thermal receptors located in the skin, transmit nerve impulses
Define evaporation
Water vaporization from the skin surface and respiratory airways which transfer heat from body to the environment
Define radiation
Emission of heat from one object and absorbed by another via electromagnetic waves (w/o physical contact). Will always travel from hot to cold, assisting heat loss
Define conduction
Transfer of heat from one object to another through physical contact.
What are the hormonal response for training in the heat
Pituitary glands release vasopressin (antidiuretic hormones) stimulate water reabsorption for the kidney
Release aldosterone which stimulate water and sodium reabsorption in the blood
Why does heat illness occur
Symptoms: core temperature 39,flushed skin, negative water balance
Occurs: peripheral vasodilation occurs which induces hypotension , large amounts of blood going to the core to cool it.
why does heat stroke occur
Symptoms: core temp > 40, thermoregulatory failure
Internal organ tissue temp rise above critical levels, cell membrane damage, disrupts cell metabolism, acid base balance
What is the cardiovascular response to heat stress
comp for blood flow between the skin and working muscle increases, greater superficial (skin) blood flow reduces venous return, SV is also reduced.
In response, HR is increased - cardiovascular drift
Define the critical core temperature
when end core temperature is reported to be 40, CNS respond with reduced neural drive, used as a safety break to prevent dangerous overheating whereby we stop exercise or intensity is sig. reduce
Define cold stress
any environmental condition that promotes loss of body heat and threatens temperature homeostasis
Define Cold Induced Vasodilation
acute, periodic increase in peripheral blood flow observed during cold exposure
Arteriovenous anastomoses (AVA) connections ( shunts) between small veins and arteries, prevent blood bypass the capillaries and instead flow directly from the arterioles to venules
Release of noradrenaline controls the AVA
Define no non-shivering thermogenesis
Increase in metabolic heat production that is not associated with muscle activity, occurs mainly through metabolism in brown adipose tissue (BAT) - rich in mitochondria which have uncoupling proteins ( thermogenin)
Outline the role of thermogenin
The transport of H+ through the inner wall of mitochondria creates energy
When thermogenin proteins are present , the H+ bypasses the ATP synthase channel
This uncouples oxidative phosphorylation, energy created from the transport of H+ to the inner walls is disspiated as heat
Define shivering thermogenesis
Thermogenic response whereby skeletal muscles rapidly contract to increase metabolic heat production
