animal form and function ch 40 n.
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Animal Form and Function ch 40. What problems do all three share ? Differences?. Animals come in a variety of sizes and shapes yet all share similar problems obtain oxygen, food, get rid of waste (exchange with environment) fight infection reproduce homeostasis.

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slide3

Animals come in a variety of sizes and shapes yet all share similar problems

    • obtain oxygen, food, get rid of waste (exchange with environment)
    • fight infection
    • reproduce
    • homeostasis
i correlation between animal form and function
I. Correlation between Animal Form and Function
  • Form fits function at all the levels of life, from molecules to organisms.
  • What limits animal form?
    • Physical laws that affect strength, movement, heat exchange, diffusion
a exchange with the environment
A. Exchange with the Environment
  • Exchange of nutrients, waste, gases occurs at the cell membrane of all cells
  • Cell membrane MUST be bathed in aqueous environment for diffusion
  • What constrains this diffusion?
    • Surface area to volume ratio of cells
1 single celled organisms
1. Single celled organisms
  • Enough surface area in contact with environment to service cytoplasm
2 simple animals with gastrovascular cavity cnidarians flatworms
2. simple animals with gastrovascular cavity (cnidarians, flatworms)
  • body walls only 2 cell layers thick so enough surface area in contact with environment
3 more complex and larger animals have organ systems for exchange
3. more complex and larger animals have organ systems for exchange
    • respiratory
    • digestive
    • excretory
  • have highly folded internal surfaces for exchange
  • these are evolutionary adaptations for increased size and help animals in variable environments maintain steady internal conditions
ii coordination and control
II. Coordination and Control
  • organ system activity is under control of nervous and endocrine systems
  • these involve cell communication and help keep an organism in homeostasis
iii feedback control maintains homeostasis
III. Feedback Control Maintains Homeostasis

A. Regulators and Conformers

  • Regulators
    • Use internal mechanisms to maintain homeostasis
  • Conformers
    • Internal conditions change along with external environment
b homeostasis
B. Homeostasis
  • ability of an organism to maintain constant internal conditions
  • body temp, blood pH, blood glucose etc in humans
  • involves feedback loops
1 negative feedback loop
1. Negative feedback loop
  • Most homeostatic control mechanisms
  • Control mechanism that moves AWAY from the stimulus
  • Ex: body temp
  • Explain:
2 positive feedback loop
2. Positive feedback loop
  • Only stressful situations
  • Control mechanism that moves TOWARDS the stimulus
  • Ex: childbirth
iv homeostatic control of thermoregulation involves form function and behavior
IV. Homeostatic control of thermoregulation involves form, function and behavior
  • Thermoregulation = process by which animals maintain an internal body temp within a specific range
  • All enzymatic and physiological processes are sensitive to changes in temp
a endothermy and ectothermy
A. Endothermyand Ectothermy
  • Endotherms: gain heat thru metabolism
  • Ectotherms: gain body heat externally
  • Endotherms must consume more food than ectotherms
  • Ectotherms can tolerate greater fluctuations in body temp than endotherms
b poikilotherms vs homeotherms
B. Poikilothermsvs Homeotherms
  • Poikilotherms body temp changes with environment
  • Homeotherms body temp is relatively constant
slide24

Is an angelfish that inhabits the waters of the Caribbean a poikilotherm or homeotherm? Endotherm or ectotherm?

c exchanging heat with the environment
C. Exchanging Heat with the Environment
  • In order to thermoregulate, organisms must gain or lose heat with the environment
  • Which way does heat move?
slide27

Which mechanisms result in heat loss?

Which mechanisms result in heat gain?

slide28

What must occur in order to maintain constant body temp?

  • In order to maintain body temp, heat loss to environment and heat gain from environment must be balanced
b mechanisms that regulate body temp
B. Mechanisms that Regulate Body Temp

1. Insulation (endotherms)

  • Hair, fur, feathers, fat layers
  • Raised fur and feathers traps heat near skin
  • Excess fat near surface prevents core body heat loss in marine mammals
  • Oily secretions in many birds and mammals that spend time in water prevents heat loss
2 dilating or constricting blood vessels endotherms and a few ectotherms
2. dilating or constricting blood vessels (endotherms and a few ectotherms):
  • Vasodilation increases the diameter of the blood vessels. This increases vessel surface area and allows excess heat to be lost
  • Vasoconstriction constricts the diameter of blood vessels. This decreases vessel surface area and prevents heat from being lost
3 evaporative cooling endotherms
3. evaporative cooling (endotherms):
  • Humans lose excess heat thru their skin (sweating)
  • Furry mammals lose excess heat thru panting.
  • This is due to the excess heat absorbed to evaporate water . Why?
4 adjusting metabolic heat production endotherms and a few ectotherms
4. Adjusting metabolic heat production (endotherms and a few ectotherms)
  • Thermogenesis: adjustment of metabolic heat production to maintain body temp
  • Shivering thermogenesis: increased muscle contraction due to increased metabolic activity
  • Nonshivering thermogenesis: hormonal increase in metabolism in brown fat cells with the production of heat vs ATP
slide37

Graph O2 consumption as a function of external temp for endotherms and exotherms.

What does O2 consumption measure?

5 behavioral changes
5. Behavioral changes
  • Ectotherms change locations
  • Hibernation/migration
v hormonal control of thermoregulation
V. Hormonal Control of Thermoregulation
  • Under control of hypothalamus
vi energy requirements are related to size activity and environment
VI. Energy requirements are related to size, activity, and environment
  • Bioenergetics = flow and transformation of energy in an animal
  • determines how much food is needed and relates to animal’s size, activity, and environment
slide42

metabolic rate: amount of NRG animal uses in a given time

  • how can metabolic rate be measured?
  • basal metabolic rate: minimum metabolic rate of endotherm in fasting, nonstressed, nongrowing, constant temp conditions
  • standard metabolic rate: minimum metabolic rate of ectotherm in fasting, nonstressed, nongrowing, constant temp conditions
slide43

1. Thermoregulation and metabolic rate

  • Who has a higher minimum metabolic rate, endotherm or ectotherm? Why?
2 size and metabolic rate
2. Size and metabolic rate

What is this graph telling?

slide46

Smaller mammals have a higher metabolic rate per gram of body and therefore a higher breathing rate, heart rate

  • Who consumes more food per unit body mass?