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Ch 40 – Animal Form & Function. Form & function. Evolution of Animal size & shape Constrained by physical forces Convergent evolution i.e. fusiform shape for aquatic animals. Seal. Penguin. Exchange with Environment. Mouth. Gastrovascular cavity.

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form function
Form & function
  • Evolution of Animal size & shape
    • Constrained by physical forces
    • Convergent evolution
      • i.e. fusiform shape for aquatic animals

Seal

Penguin

exchange with environment
Exchange with Environment

Mouth

Gastrovascular

cavity

  • All cells need access to aqueous environment
  • Why?
  • How do surface area & volume relate to exchange of materials?

Exchange

Exchange

Exchange

0.1 mm

1 mm

(a) Single cell

(b) Two layers of cells

slide4

More complex animals – have highly folded internal surfaces for maximum exchange

Villi

Advantages of a complex body:

Protection

Sensory organs

Better able to deal with environmental changes

nutrition microvilli
Nutrition/ Microvilli

http://www.youtube.com/watch?v=AJ1wKsmBPvA

excretion nephron
Excretion/Nephron

http://www.youtube.com/watch?v=glu0dzK4dbU

organization of body plan
Organization of body plan
  • Cells  Tissues  Organs  Organ systems
  • What coordinates & controls the systems?
feedback control helps maintain a stable environment
Feedback control helps maintain a stable environment
  • regulator – animal that uses internal mechanisms to control internal environment
  • conformer – animal that allows internal environment to change in response to external variable
homeostasis
Homeostasis
  • -maintain a “steady state” or internal balance regardless of external environment
  • In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level
  • For a given variable, fluctuations above or below a set point serve as a stimulus
  • - sensor detects & triggers response
negative feedback
Negative feedback –
  • Control that reduces the original stimulus; maintains homeostasis by returning to “normal range”
positive feedback
Positive feedback
  • Control mechanism that amplifies the stimulus (is not used for maintenance of homeostasis)
alterations in homeostasis
Alterations in homeostasis
  • Set points and normal ranges can change with age or show cyclic variation
  • In animals and plants, a circadian rhythm governs physiological changes that occur roughly every 24 hours
  • Homeostasis can adjust to changes in external environment, a process called acclimatization
thermoregulation an example of homeostasis
Thermoregulation: an example of homeostasis
  • the process by which animals maintain an internal temperature within a tolerable range
endothermy and ectothermy
Endothermy and Ectothermy
  • Endothermic animals generate heat by metabolism; birds and mammals are endotherms, some insects
  • (have more stable temperature in a changing environment)
  • Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and nonavianreptiles
  • (tolerate larger range of temperatures)
balancing heat gain heat loss
Balancing heat gain & heat loss
  • Organisms exchange heat by four physical processes:
adaptations for heat regulation
Adaptations for heat regulation
  • Insulation
  • - major thermoregulatory adaptation in mammals and birds
  • Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment
  • The integumentary system is frequently involved in regulation
  • - skin, hair, nails
circulatory adaptations
Circulatory adaptations
  • Regulation of blood flow near the body surface significantly affects thermoregulation
  • Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin
  • Vasodilation - blood flow in the skin increases, facilitating heat loss
  • Vasoconstriction - blood flow in the skin decreases, lowering heat loss
circulatory adaptations1
Circulatory adaptations

Countercurrent heat exchange – in many birds & mammals, also sharks, dolphins

  • Warm blood from arteries is used to warm blood in adjacent veins
  • allows for transfer of heat to colder blood coming from extremities
circulatory adaptations2
Circulatory adaptations
  • Evaporative heat loss –
  • water absorbs heat when it evaporates, so heat is carried away from surface by water vapor
  • Adaptations: sweat glands, birds with pouch with blood vessels in mouth
behavioral responses
Behavioral responses
  • move to warmer or cooler area
  • move closer together
  • Some insects have specific postures for thermoregulation
adjusting metabolic heat production
Adjusting metabolic heat production
  • Thermogenesis:
  • - adjustment of metabolic heat production to maintain body temperature
  • - increased by muscle activity such as moving or shivering
  • - Nonshiveringthermogenesis takes place when hormones cause mitochondria to increase their metabolic activity (heat vs. ATP)
  • - Some ectotherms can also shiver to increase body temperature
acclimatization in thermoregulation
Acclimatization in Thermoregulation
  • Birds and mammals can vary their insulation to acclimatize to seasonal temperature changes
  • When temperatures are subzero, some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells
slide28

Thermoregulation is controlled by a region of the brain called the hypothalamus

  • The hypothalamus triggers heat loss or heat generating mechanisms
  • Fever is the result of a change to the set point for a biological thermostat – helps fight infection.
bioenergetics
Bioenergetics
  • - the overall flow and transformation of energy in an animal
  • - determines how much food an animal needs and it relates to an animal’s size, activity, and environment
  • Ectotherms use less energy than endotherms
slide30

Metabolic rate is the amount of energy an animal uses in a unit of time

How can metabolic rate be measured?

slide31

Influences on metabolic rate

Size – rate is proportional to body mass, smaller animals have higher metabolic rate per gram than larger animals

activity metabolic rate
Activity & metabolic rate
  • Activity greatly affects metabolic rate for endotherms and ectotherms
  • In general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity
  • Endotherms – high energy strategy, can have intense, long-duration activity
  • Ectotherms – low energy strategy,usually incapable of intense activity over long periods
energy budgets
Energy budgets

Reproduction – high energy cost

strategies: seasonal reproduction,

life history strategy – i.e. diapause (in insects)

torpor energy conservation
Torpor & Energy conservation
  • Torpor – physiological state of decreased activity -small mammals & birds – daily torpor (i.e. bats feed at night, torpor in day)
  • Hibernation – body’s thermostat is turned down in winter, due to cold & food scarcity (seasonal response)
  • Estivation – summer torpor – due to high temp & scarce water supplies
slide35

bear hibernation

  • http://animal.discovery.com/tv-shows/animal-planet-presents/videos/natural-world-bear-hibernation.htm
  • Thermoregulation in animals (4:08)
  • http://www.youtube.com/watch?v=NJEBfl_LKno
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