Week 7: Textbook readings Flashcards
What is a regulator in terms of environmental variables?
An animal that uses internal mechanisms to keep its internal conditions stable despite external changes
What is a conformer in terms of environmental variables?
An animal that lets its internal conditions change along with external environmental changes.
Homeostasis
The process by which an organism maintains a stable internal environment
Negative feedback
A control mechanism that reduces or reverses a change to maintain stability
Positive feedback
A control mechanism that amplifies a change, moving the system further from stability
Acclimatization
When an animal remodels itself in response to complex environmental changes
Acclimation
When an animal remodels itself in response to a single environmental factor, usually in a controlled setting
Thermoregulation
- Process by which animals maintain an internal temperature within a tolerable range
- Each animal species has an optimal temperature range
Endotherm
animal that uses internal metabolic processes as a major heat source
Ectotherm
An animal that relies on external sources of heat to regulate its body temperature
Poikilotherm
has a body temperature that varies with environmental conditions
Homeotherm
has a relatively constant body temperature
Heterotherm
- An animal that switches between endothermy and ectothermy, depending on conditions
- Ex. when hibernating
Spatial heterothermy
animal that maintains different temperatures in specific regions of the body
Temporal heterothermy
An animal that temporarily changes its body temperature by adjusting heat production and loss
Integumentary system
The outer covering of the body, consisting of the skin, hair, and nails
Why do animals use insulation?
To reduce overall heat exchange and help thermoregulate
How do land mammals and birds respond to cold temperatures?
They raise their fur or feathers to trap a thicker layer of air, increasing insulation
insulation - marine mammals
- They use blubber for insulation
- they swim in cold water, often near freezing, which is much colder than their body core temperature
Vasodilation
- The widening of blood vessels to increase blood flow
- usually to help the body lose heat
Vasoconstriction
- The narrowing of blood vessels to reduce blood flow
- Helps the body conserve heat
Countercurrent Exchange
- When heat or substances are transferred between fluids flowing in opposite directions
- Helps keep a stable internal environment
What is brown adipose tissue (BAT)?
- A special type of fat tissue that produces heat instead of ATP
- Produces the protein thermogenin
What does thermogenin do?
- Makes mitochondria generate heat instead of ATP
- process called nonshivering thermogenesis (NST)
In general which animals produce BAT?
- Infants, small mammals, and cold-climate animals
- Larger or tropical mammals usually don’t produce BAT due to gene mutations
What part of the brain regulates body temperature in mammals?
- The hypothalamus
- using feedback mechanisms and warm/cold receptors
How does the hypothalamus respond to cold temperatures?
It activates heat-saving (vasoconstriction, fur raising) and heat-generating mechanisms (shivering)
How does the hypothalamus respond to high temperatures?
It promotes cooling (vasodilation, sweating, panting) and shuts down heat-retention mechanisms
