Lecture 1: Homeostasis Flashcards
What is homeostasis in terms of thermoregulation?
Maintenance of a constant (normal) internal environment by coordinated responses (more than 1 system) of organs/systems that automatically compensate for Environmental changes.
EX. blood pressure, body temperate, O2/CO2 levels
What is a thermoneutral zone?
What are critical temperatures?
Thermoneutralzone is the ambient temperature at which no adjustment is needed. Therefore no additional energy is required to maintain the body temp.
Critical temperatures: hot or cold temps which require energy to maintain homeothermic conditions. (produce or actively dissipate heat)
What is hyperthermia and hypothermia and how it affects the body?
Hyper: heat stress which is generally fatal, cells can’t function due to enzymes and proteins denatured
Hypo: Cold stress, cells can survive freezing but blood circulation and respiration can’t function and fail which results in death
What can mammals and birds be described as in terms of regulating body temperature?
What is the “sweet spot” temperature for most birds and mammals?
Why do Lactating dairy cows have a higher temperature then non-lactating.
They are known as endotherms which means they are able to maintain a stable internal body temperature regardless of external influence. (they are able to generate and dissipate heat on their own)
Sweet spot is known as 37-39 degrees C
Dairy cows that are lactating are using energy to create milk which generates heat, therefore they have a higher body temp.
What are the 3 physical processes of heat loss through gradient physical laws and 4 though evaporation? and what happens?
GRAD PHYSICAL LAWS
Radiation: electromagnetic radiation is emitted and absorbed to surface and temp of the object/animal
Conduction: Transfer through contact, depends on the conductivity ex animal to ground
Convection: transfer via moving air or water
EVAPORATION
Passive evaporation: normal water loss
Sweating: active SNS results in the loss of ions
Panting: Rapid shallow breathing (not in horses and pigs)
Bathing: Water absorbs energy before evaporating
How is Extra-Heat Produced?
Muscle activity: Shivering, rhythmic involuntary antagonistic muscle contractions simultaneously. NO EXERCISE.
Non-shivering thermogenesis: sympathetic nervous system results in secretion of adrenalin which increases metabolism from (brown fat usually). Thyroid hormones also increase metabolism.
How is Extra-Heat Lost?
Normal conditions, metabolic heat is removed from the core by the blood close to the skin.
Insulation property of the skin is inversely proportional to the blood flow. Ie low insulation, higher blood flow (vasodilation) to the skin so the heat can dissipate. (opposite is true for vasoconstriction.)
What is the automatic and volentary process of thermoregulation and the system components?
AUTOMATIC (REFLEX)
sensor+integration+effectors
Sensor: Thermoreceptors = nerve cells
Integration Centre: Hypothalamus = info compared to internal reference set points
Effectors: Neurons = connected to muscles for shivering
SNS = Blood flow, sweat glands, metabolism
Hormones
VOLUNTARY
Hypothalamus connected to the cortex = exchange of info
change in behavioural response = cognitive behaviour (cows going in shade on hot day)
Are cold sensory fibres or warm sensory fibres more numerous?
Cold sensory fibres.
