Lecture 23 - Form and Function II Flashcards
Why does body size matter?
Bones of small animals are relatively thin compared to bones of large animals. Metabolic rates increase as body mass decreases. Very small animals can breathe through skin whereas larger animals require specialized organs to breathe. (many fish larvae breathe thru their skin and adult fish breathe with their gills).
Why are the bones of small animals relatively thinner than the bones of large animals?
THey are relatively less massive, mass scales with volume. Elephants need relatively larger bones to support their relatively greater mass.
How do big animals get enough oxygen with relatively small surface area to volume ratios?
They increase surface area within their bodies - folding, branching, and flattening.
Adaptations that increase the surface area
Alveoli are highly folded to increase oxygen uptake, Capillaries are highly branched to increase oxygen uptake and delivery. Lamellae on fish gills are very flat in order to increase oxygen uptake
How do African Elephants increase their surface area to stay cool?
Many capillaries that are in their big ears can help them lose heat. Asian elephants live in cooler climates and thus have smaller ears.
What is homeostasis?
The stability in chemical and physical conditions within an organism’s cells, tissues, and organs. Temperature, pH, calcium ion concentration, and salinity levels are used to measure homeostasis. Organisms function optimally when homeostasis is achieved.
Importance of thermo-homeostasis
At high temperatures; proteins denature and cease functioning, and there is excessive water loss and dehydration. At low temperatures, enzyme function and energy production is slowed.
Endothermic regulation
Is the gain of body heat from internal metabolic processes. Elephants always maintain a body heat of around 97.7 F regardless of outside environment.
Endothermic regulation regulators
Sensors: read inside and outside temp (skin, spinal cord, hypothalamus)
Integrators: Change body temperature to return it to set point (blood vessels dilate/contract near skin when hot/cold, sweat glands stimulate and evaporate sweat to cause heat loss, respiratory sensors cause panting to cause heat loss, shivering to produce heat, chemical signals arrive at cells to cause more cellular respiration and heat production)
Ectothermic regulation
Gaining of body heat from an external source. A turtle’s body temperature matches the temperature of its environment. A sensor senses external or internal temperature, an integrator evaluates temp and sees if a response is necessary, and an effector is the behavioral response.
Example of ectothermic effector response
Too cold - sunbathe
Too hot - return to water
Endotherms vs ectotherms
Endotherms: basal metabolic rates are extremely high, metabolic heat warms the body, have insulating structures such as feathers or fur.
Ectotherms: basal metabolic rates are relatively low, gain heat directly from the environment, lack insulating structures
Relative to body mass, do ectothermic or endothermic animals require more food? Why?
Endotherms require more food, as producing metabolic heat costs a lot of energy
