Thermoregulation

dehydration as a source of heat?

-loss of water → loss of evaporative cooling or sweating (less heat escape)

-reduced BV → less heat transfer to skin surface

-dehydration → increased metabolic activity via sympa → increase in heat residual

summary:

convection

-heat transfer through the movement of a fluid (air or water) over a surface

-breeze blowing over an animal’s skin increases heat loss → cooling by convection

-water currents moving past the body greatly affect heat exchange (since water conducts heat much better than air)

definition:

conduction

-direct heat transfer between two objects in contact

(ie. animal laying on ground)

definition:

convection

-heat transfer via moving air or water

(ie. wind over skin)

definition:

radiation

-heat transfer through electromagnetic waves

(ie. sun warming animal)

definition: 

evaporation

-heat loss via vaporizing water

(ie. sweating, panting)

where are peripheral thermoreceptors located?

-skin

-mucous membrane

summary:

insensible heat loss

-occurs without being noticed, such as through respiration or diffusion through the skin

-not necessarily tied to active thermoregulation

summary: 

sensible heat loss 

-noticeable and measurable, such as through sweating

What do central thermoreceptors do?

– continuous sensor of core body T

Examples:

Heat losing mechanisms

-vasodilation

-sweating

-pantingpanting

Examples:

Heat conserving mechanisms

-shivering

-metabolism increase through hormone control

-vasoconstriction

definition:

sheep grazier warnings

-official warnings for sheep farmers and grazers that there might be hypothermic conditions for sheep

-Cold weather only

– Particularly young or recently shorn sheep

summary:

apocrine glands

-found in the dermis

-secrete a thick, protein-rich, milky fluid into hair follicles rather than directly onto the skin surface

-fx: scent, communication, and minor thermoregulation

definition:

wallowing

(pigs)

-when they cover themselves in mud to promote evaporation

Summary:

Respiratory evaporation

-animal breathes out moist, warm air and breathes in cooler, drier air, water evaporates from the respiratory surfaces → heat is lost with that water vapor

Inhaled air cooler and drier than body T → passes over nasal cavity/mouth/trachea mucosa → warmed and humidified → exhalation → water leaves as vapor → heat away from the body