1. Ch. 40 Warm up Define and give an example of homeostasis.
Sequence the organization of living things from cell to biome.
Describe negative and positive feedback.

2. Chapter 40 Basic Principles of Animal Form and Function

3. Overview: Diverse Forms, Common Challenges
Anatomy: the study of the biological form (STRUCTURE) of an organism
Physiology: the study of the biological FUNCTIONS an organism performs
Structure dictates function!

4. Figure 40.1
Figure 40.1 How does a jackrabbit keep from overheating?
The jackrabbit’s large ears provide an expansive area of exposed skin loaded with blood vessels. When the surrounding air temperature is slightly below the rabbit’s body temperature, as when it retreats from hot desert sun into shade, the blood vessels in the outer part of its ears widen. This increases the surface-area-to-volume ratio of the vessels, a response that favors heat loss to the surrounding air, lowering the rabbit’s body temperature. This reduces the need for evaporative cooling mechanisms, such as panting or sweating, and is thereby an important water-conservation technique given the jackrabbit's arid habitat.  At air temperatures around 30° C, convection from the jackrabbit's ears can shed all of the animal’s excess heat. 4

5. Animal form and function are correlated at all levels of organization
Size and shape affect the way an animal interacts with its environment
Many different animal body plans have evolved and are determined by the genome

6. Hierarchical Organization of Body Plans
Cells  Tissues  Organs  Organ Systems

7. Four main types of tissues:
Epithelial: covers the outside of the body and lines the organs and cavities within the body
Connective: binds and supports other tissues (cartilage, tendons, ligaments, bone, blood, adipose)
Muscle: controls body movement (skeletal, smooth, cardiac)
Nervous: senses stimuli and transmits signals throughout the animal (neurons, glia)

12. Coordination and Control Within a Body
Endocrine system: transmits chemical signals (hormones) to receptive cells throughout body via blood
Slow acting, long-lasting effects
Nervous system: neurons transmit info between specific locations
Very fast!
Info received by: neurons, muscle cells, endocrine cells

14. Homeostasis
Maintain a “steady state” or internal balance regardless of external environment
Fluctuations above/below a set point serve as a stimulus; these are detected by a sensor and trigger a response
The response returns the variable to the set point

16. Negative Feedback Positive Feedback
“More gets you less.”
Return changing conditions back to set point
Examples:
Temperature
Blood glucose levels
Blood pH
Plants: response to water limitations
“More gets you more.”
Response moves variable further away from set point
Stimulus amplifies a response
Examples:
Lactation in mammals
Onset of labor in childbirth
Plants: ripening of fruit
Speed Sign Example: Responding to the feedback by slowing down or speeding up to remain around the “set point”
Negative Feedback Loop: Body temperature increases: Start to sweat and vasodilation. Temperature goes down. Start to shiver and vasoconstriction holding the body heat close to my body.
Negative: Hormone production; insulin (when blood sugar levels rise, the pancreas produces more insulin, and once it takes effect and blood sugar levels lower, the pancreas stops insulin production.) blood pressure.
Dance back and forth around a “set point”!!!!
Positive: want to go in one direction away from the “set point”
Example: Child birth- head of the baby on the cervix… pressure gets stronger and positive feedback brings childbirth to completion.

17. The homeostatic control system example: Receptor (thermometer)
The homeostatic control system example: Receptor (thermometer). When a room falls below a “set point”, the thermostat (control center) switches the heater (the effector).

18. Figure 40.16
Figure The thermostatic function of the hypothalamus in human thermoregulation. 18

19. Thermoregulation
Maintain an internal temperature within a tolerable range
Endothermic animals generate heat by metabolism (birds and mammals)
Ectothermic animals gain heat from external sources (invertebrates, fishes, amphibians, and nonavian reptiles)
Q: Which is more active at greater temperature variations?
Q: Which requires more energy?
Many endotherms and some ectotherms can alter the amount of blood (and hence heat) flowing between the body core and the skin. Elevated blood flow in the skin results from vasodilation, an increase in the diameter of superficial blood vessels triggered by nerve signals that relax the muscles of the vessel walls. In endotherms, vasodilation usually warms the skin, increasing the transfer of body heat to a cool environment by radiation, conduction, and convection. The reverse process, vasoconstriction, reduces blood flow and heat transfer by decreasing the diameter of superficial vessels.
It may involve physiological changes such as panting, sweating, shivering, or behavioral changes such as burrowing and sunning.

20. Figure 40.10
Figure Endothermy and ectothermy. 20

21. Balancing Heat Loss and Gain
Organisms exchange heat by four physical processes: radiation, evaporation, convection, and conduction
Radiation: the emission of electromagnetic waves by all objects warmer than absolute zero
Evaporation: the removal of heat energy from the surface of a liquid that is losing some of its molecules
Convection: the mass movement of warmed air or liquid to or from the surface of a body or object
Conduction: the direct transfer of thermal motion (heat) between molecules of objects in direct contact with each other

22. Five adaptations for thermoregulation:
Insulation (skin, feather, fur, blubber)
Circulatory adaptations (countercurrent exchange)
Cooling by evaporative heat loss (sweat)
Behavioral responses (shivering)
Adjusting metabolic heat production (“antifreeze”)
Many species of flying insects use shivering to warm up before taking flight.
Honeybees: huddle together if it is too cold and if it is too hot they control the temperature of their hive by transporting water to it in hot weather and fanning with their wings, which promotes evaporation and convection.
Shedding fur or growing a thicker coat of fur or blubber: acclimatization (could take a few days or a few weeks)

23. Figure 40.12
An important arrangement of the blood vessels for reducing heat loss in many endotherms, including many marine mammals and birds.
Traps heat in the body core, thus reducing heat loss from the extremities, which are often immersed in cold water or in contact with the snow. In essence, heat in the arterial blood emerging from the body core is transferred directly to the return in the venous blood instead of being lost to the environment.
Some specialized bony fishes and sharks also possess countercurrent exchangers. Many endothermic insects have countercurrent heat exchangers that help maintain a high temperature in the thorax.
Evidence for common ancestry in animals: Countercurrent exchange systems 23

24. Energy Use
Metabolic rate: amount of energy an animal uses in a unit of time
Basal metabolic rate (BMR): endotherm at rest at a “comfortable” temperature
Standard metabolic rate (SMR): ectotherm at rest at a specific temperature
Ectotherms have much lower metabolic rates than endotherms of a comparable size
Basal Metabolic Rate (BMR): the metabolic rate of a nongrowing endotherm that is at rest, has an empty stomach, and is not experiencing any stress.
Standard Metabolic Rate (SMR): the metabolic rate of a fasting, resting, nonstressed ectotherm

25. Figure 40.19
Figure The relationship of metabolic rate to body size. 25

26. Torpor and Energy Conservation
Torpor is a physiological state in which activity is low and metabolism decreases
Save energy while avoiding difficult and dangerous conditions
Hibernation: torpor during winter cold and food scarcity
Estivation: summer torpor, survive long periods of high temperatures and scarce water
Bats go into daily torpor during the day. Chickadees and hummingbirds during cold nights.