W6 Thermoregulatory System Flashcards
What is Thermoregulation?
- To regulate temperature, in this case within your body.
- What is Vasodilation?
- What is Vasoconstriction?
- Vasodilation occurs when the body is too hot. Blood vessels get larger (dilate) and get closer to the surface of the skin allowing blood to be cooled.
- Vasoconstriction occurs when the body is too cold. Blood vessels become narrower (constrict) to keep the blood warmer and away from the surface of the skin.
What are the three types of Thermoregulation? Please describe each of them
- Homeotherms
- Constant regulation of internal body temperature regardless of external stimulus - Endotherms
- Generate heat internally
- Maintain high basal (base layer) heat production - Ectotherms
- Depend on external heat sources
- Temperature changes with environment
What is the internal temperature of our core?
36.5 - 37.5 degrees
What is hypothermia?
- When the bodies core drops below 35 degrees
- COLD ONE!
What is hyperthermia?
- When the bodies core rises above 38 degrees
- HOT ONE!
Give a few factors influencing body temperature:
- Body mass/composition
- Heat loss via environment (e.g. humidity)
- Heat loss via Skin (e.g. surface area)
- Metabolic heat production
What is the definition of Specific Heat Capacity?
- The amount of energy required to raise the temperature of a given substance by 1 degree
What is the law of the conservation of energy?
- Energy cannot be created or destroyed, it can only be transformed from one state to another
How do we produce heat?
- Chemical energy in the food we eat (use it to re-synthesize ATP but its inefficient)
- Voluntary = Exercise
- Involuntary = Shivering & Action of hormones
Can we use VO2 as an indicator as the amount of heat produced?
Yes, 1L of O2 is ~20KJ of heat
Name a few place you can measure core temperature with a thermometer:
- Oral (under tongue)
- Ear drum
- Rectum
- Oesophagus
- Intestinal
Name three things skin temperature depends on:
- Ambiant temperature
- Distance from core
- Skin blood flow
How does heat loss occur? (4 things)
- Evaporation (liquid into vapour)
- Radiation (emission/electromagnetic waves)
- Convection (hot rises, cold falls creates currents/movement)
- Conduction (directly transmitted through)
How can we receive external heat gain?
- Sky thermal radiation
- Solar radiation (reflected)
- Ground thermal radiation
What is thermal gradient?
Heat transfer is always from high temperature to low temperature.
- What is evaporation?
- 1 gram of sweat = how many KJ’s of heat energy
- Process of changing liquid (sweat) into vapour
- 1g sweat = 2.41KJ of heat
What system activates our sweat glands?
- Our Sympathetic Nervous System (SNS) stimulates our sweat glands which is where sweat is released from
- Increased SNS when exercising (anticipation or nerves)
What factors influence evaporation? Do they increase or decrease it?
- Air temperature (humidity) = decreases
- Convection currents (wind) = increases
- Skin exposure (surface) = increases
What does sweat rate depend on?
- Body size
- Absolute VO2
- Aerobic fitness
- Heat accumulation
- Environment
What is a negative feedback loop?
- This is where you are trying to get the body back to homeostasis (by either heating or cooling)
What are the physiological responses to hyperthermia (high temperature)?
- Starts with Heat Load is can be detected in the skin or the core
- Signals sent to hypothalamus (brain)
- Lastly, either start vasodilation and/or begin sweating
What are the physiological responses to hypothermia (cold temperature)?
- Starts with Heat Load is can be detected in the skin or the core
- Signals sent to hypothalamus (brain)
- Lastly, either start vasoconstriction, shivering, release catecholamine and/or release thyroxin
Whats the definition of Q10 (temperature coefficient)?
- It is a measure of the rate of change of a biological or chemical system as a consequence of increasing the temperature by 10 degrees
Why is performance impaired with a high core temperature?
Cascade of affects:
- Increases sweating
- This decreases plasma volume
- This decreases blood volume
- Which starts venous return
- Lastly, decreases end diastolic volume
What are the cardiovascular consequences of a high core temperature?
- Stroke volume = Decreased
- Heart rate = Increase
- Cardiac output = Decreased
- Blood pressure = Decreased
- Total peripheral resistance = Increase
- Muscle blood flow = Decreased
What are the metabolic consequences of a high core temperature?
- VO2max = Decreased
- Anaerobic metabolism = Increase
- Muscle lactate = Increase
What are the cognitive consequences of a high core temperature?
Impairment in: - Reaction Time - Attention - Visual motor tracking - Fatigue perception increased Central fatigue: - Brain stops sending out the neural impulses to contract the muscles to stop you exercising.
What’s the treatment for heat exhaustion and heat stroke?
Treatment for Heat Exhaustion: - Cooler environment - Elevate feet - Saline (Oral or Intravenous) Treatment for Heat Stroke: - Rapidly cool body (cold water, ice bath, wet towel) - Seek medical attention
What are the affects of heat acclimation?
- Body temperature will be lower at a given heat
- Sweat rate increases and sweat becomes more dilute
- Skin blood flow is reduced more blood to muscles
- Blood volume increases or doesn’t decrease
- Stroke volume maintained
What is the importance of hydration?
- Staying hydrated
- Cool drinks can help lower temperature
- Cool drinks are absorbed in the GI tract quicker
