Physiology, Homeostasis, and Temperature Regulation

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Physiology, Homeostasis, and Temperature
Regulation
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Physiology

• study of the functions of organisms and their
  parts
• structural hierarchy
• cell
• tissue
• organ
• organ system
• organism

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Organ Systems

• Integumentary
• Digestive
• Circulatory
• Respiratory
• Immune and Lymphatic
• Excretory
• Endocrine

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Organ Systems

• Reproductive
• Nervous
• Muscular
• Skeletal

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Homeostasis

• maintenance of a constant internal environment
• dynamic equilibrium
• internal vs. external environment
• interstitial fluid

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Homeostasis

• feedback circuit
• receptor
• control center (integration)
• effector (controlled system)
• controlled by regulatory systems

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Homeostasis

• negative feedback
• positive feedback

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Body Plans and Homeostasis

• size, shape, and features
• demand for support as size increases
• exchange of energy and materials with
  surroundings
• maximize exposure
• surface area to volume ratio

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Body Plans and Energy Flow

• 1. Animals must ingest organic compounds
• use energy from nutrients to make own
  macromolecules
• use glucose to make ATP via oxidative metabolism

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Body Plans and Energy Flow

• 2. Surface areavolume ratio is critical
• cells can be thought of as closed systems
• e.g. use of O2 and glucose to make ATP
• How does cell get O2?
• rate of diffusion is proportional to the cells
  S.A. divided by its volume

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Body Plans and Energy Flow

• 3. As an animal becomes progressively larger
  (with no change in shape), the flow of the solute
  in or out of the cells will have progressively
  less effect on the internal concentration
• surface area to volume ratio decreases

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Body Plans and Energy Flow

• 4. Animals are closed systems and are subject to
  S.A.volume restrictions
• cells exchange solutes with the interstitial
  fluid
• Where do these chemicals come from?
• animals body plans are modified to maintain a
  high S.A.volume

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Body Plans and Energy Flow

• 5. Animals have evolved elaborate structures to
  increase S.Avolume
• folding and branching surfaces

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Temperature and Life

• most animals must maintain temperature above 0º C
  
• proteins tend to denature above 45º C

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Q10

• within thermal limits, temp change can cause
  problems
• most metabolic reactions are temperature
  sensitive
• Q10 is a measure of temp sensitivity

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Q10

• Q10 RT / RT-10
• rate of a reaction at temperature RT divided by
  the rate of the same reaction 10º C lower
• most biological values are 2-3
• true within a functional temperature range

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Acclimatization

• physiological change in response to seasonal
  climate changes
• accomplished through metabolic compensation

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Temperature Maintenance

• homeotherm
• poikilotherm
• heterotherm
• endotherm
• ectotherm

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Thermoregulation and Behavior
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Thermoregulation and Skin Perfusion
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Some Ectotherms Produce Heat
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Ectotherms and Heat Conservation

• cold fish vs. hot fish
• countercurrent heat exchange

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Endotherm Thermoregulation

• adjust metabolic rate or behavior in response to
  environmental temperature changes
• thermoneutral zone
• if below
• shivering thermogenesis
• nonshivering thermogenesis
• decreased blood flow to skin
• if above
• increased blood flow to skin
• evaporative water loss

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Endotherm Thermoregulation

• body plan modifications
• hair
• feathers
• shorter appendages
• rounder body shapes

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Internal Regulation

• vertebrates have the hypothalamus
• uses feedback to control internal body
  temperatures
• increase in heat production is proportional to
  the temperature the hypothalamus is cooled below
  the set point

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Conserving Energy

• achieved by lowering metabolic rate
• daily torpor
• hibernation

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