BIOL 3151: Principles of Animal Physiology

1. ANIMAL PHYSIOLOGY BIOL 3151: Principles of Animal Physiology Dr. Tyler Evans Email: tyler.evans@csueastbay.edu Phone: 510-885-3475 Office Hours: M,W 10:30-12:00 or appointment Website: http://evanslabcsueb.weebly.com/

2. PREVIOUS LECTURE Concept of UNITY IN DIVERSITY: despite great animal diversity, there are many commonalities within physiology and unifying themes that apply to all physiological processes

3. PREVIOUS LECTURE UNIFYING THEMES IN PHYSIOLOGY • Physiological processes obey physical and chemical laws • Physiological processes are regulated to maintain internal conditions within acceptable ranges • The physiological state of an animal is part of its phenotype, which arises as the product of the genetic make-up (genotype) and its interaction with its environment. • The genotype is a product of evolutionary change in a population of organisms over many generations

4. TODAY’S LECTURE Basic Principles of Chemistry and Biochemistry in Physiology (Chapter 2) • principles of chemistry and biochemistry underlie physiological processes textbook Fig 2.1 pg 22

5. TODAY’S LECTURE Basic Principles of Chemistry and Biochemistry in Physiology (Chapter 2) • chemical and biochemical processes occurring at the molecular level ultimately influence higher levels of function such as physiology

6. ENERGETICS • some of the most important chemical and biochemical processes that influence physiological function involve energy transfer or ENERGETICS • Energetics can occur on various scales: • e.g. LARGE-SCALE • transfer of energy between components of ecosystems

7. ENERGETICS • some of the most important chemical and biochemical processes that influence physiological function involve energy transfer or ENERGETICS • energetics can occur on various scales: • e.g. SMALL-SCALE • All the chemical reactions that occur within cells to make produce energy to drive physiological processes

8. ENERGETICS • in order to remain in energetic balance, cells must produce energy at rates that match demand • e.g. Mammalian heart • heart cells consume 30units of energy per minute • thus heart cells must produce at least 30 units of energy per minute to maintain cardiac function • even a 10% drop in energy production, would leave heart cells severely depleted of energy

9. ENERGETICS Acquiring, Storing and Using Energy • energy is the ability to do work, thus obtaining energy is of fundamental importance for animals • in the context of biological systems, energy comes in several forms: 1.) RADIANT ENERGY 2.) MECHANICAL ENERGY 3.) ELECTRICAL ENERGY 4.) THERMAL (HEAT) ENERGY 5.) CHEMICAL ENERGY • Different animals have evolved different strategies for acquiring and using energy textbook pg 23

10. CHEMISTRY Acquiring, Storing and Using Energy 1.) RADIANT ENERGY (i.e. energy from light) • energy released from an object and transmitted to another object by waves or particles of light. The sun is the most obvious source of radiant energy. • some animals are highly dependent on radiant energy • e.g. corals most reef-building corals contain photosynthetic algae, called ZOOXANTHELLAE, that live in their tissues zooxanthellae supply the coral with energy, which they then use to fuel their physiology

11. ENERGETICS Acquiring, Storing and Using Energy 2.) MECHANICAL ENERGY • energy that can be used to move objects from place to place • mechanical energy has important roles in animal locomotion • A kangaroo uses mechanical energy stored in its legs to hop • A flying bird uses its wings to produce the mechanical energy required for flight textbook pg 23

12. ENERGETICS Acquiring, Storing and Using Energy 3.) ELECTRICAL ENERGY • energy that results from the movement of charged particles down a charge gradient • important physiological processes depend on electrical energy: • last lecture we discussed how muscles and nerve cells use electrical signals to drive muscle contraction

13. ENERGETICS Acquiring, Storing and Using Energy 3.) ELECTRICAL ENERGY • in living systems, electrical energy is generated by CHEMICAL GRADIENTS or differences in the concentration of charged particles in between two regions • however, molecules within a system tend to disperse or DIFFUSE randomly within the available space (recall the 2nd law of thermodynamics)

14. ENERGETICS Acquiring, Storing and Using Energy 3.) ELECTRICAL ENERGY • biological systems invest energy to move molecules out of a random distribution • this creates a chemical gradient that is a form of stored energy • the cell can then release this energy to do physiological work • much more energy released, than it takes to form the gradient ENERGY

15. ENERGETICS Acquiring, Storing and Using Energy 3.) ELECTRICAL ENERGY • of particular importance to living systems are chemical gradients that form across cell membranes • ensuring that more negatively charged molecules are present inside cells than outside creates a chemical gradient or stored electrical energy • this electrical energy can be released to create electric signals that drive physiological processes • for example, muscle contraction textbook Fig 2.2 pg 24

16. ENERGETICS Acquiring, Storing and Using Energy 4.) THERMAL (HEAT) ENERGY • temperature governs virtually every aspect of physiological function • due to the fact that temperature strongly influences chemical reactions • importance of thermal energy is best shown inthe activity of ENZYMES • ENZYMES are proteins that catalyze (speed up) chemical reactions in cells

17. ENERGETICS Acquiring, Storing and Using Energy 4.) THERMAL (HEAT) ENERGY • every enzyme has a characteristic optimal activity under certain temperatures: • temperature accelerates reaction rates until the enzyme itself becomes damaged by excess heat and no longer functional textbook Fig 2.16 pg 39

18. ENERGETICS Acquiring, Storing and Using Energy 4.) THERMAL (HEAT) ENERGY Enzymes exhibit a two-phase response to temperature: activity increases as a consequence of the of the rate-enhancing effects of temperature on enzymes. at higher temperatures the destructive effects of temperature take over and rates of activity decline rate enhancing effects destructive effects enzyme reaction rate Temperature (°C)

19. CHEMISTRY Acquiring, Storing and Using Energy 4.) THERMAL (HEAT) ENERGY • because physiological function is dependent upon enzymes, a number of physiological processes show this two phase response. e.g. Heart rate in marine crabs

20. CHEMISTRY Acquiring, Storing and Using Energy 4.) THERMAL (HEAT) ENERGY • enzymes have evolved to function under temperatures most frequently encountered in nature • as a result, the range of conditions enzymes remain active is a good indication of the temperature ranges experienced by particular organisms e.g. humans vs. hot spring bacteria

21. CHEMISTRY Acquiring, Storing and Using Energy 4.) THERMAL (HEAT) ENERGY • thermal stability of enzymes in animals from different habitats

22. ENERGETICS Acquiring, Storing and Using Energy 4.) THERMAL (HEAT) ENERGY What range of temperatures would you expect these crabs to encounter?

23. ENERGETICS Acquiring, Storing and Using Energy 5.) CHEMICAL ENERGY • animals re-arrange or break down chemical bonds to release or store energy • adenosine-5’-triphosphate (or ATP) is the most versatile high energy molecule and participates in many reactions • metabolism, the sum of energy producing and energy consuming pathways in the cell, centers around the production of ATP textbook Fig 2.19 pg 42

24. ENERGETICS Acquiring, Storing and Using Energy 5.) CHEMICAL ENERGY Important ATP-Dependent Pathways • GLYCOLYSIS: • pathway that breaks down glucose (sugar obtained from food) to produce ATP • glycolysis is a vital source of energy because it can proceed in the absence of oxygen and produce ATP very rapidly (albeit for only brief periods) • produces four ATP per molecule of glucose GLUCOSE textbook pg 49

25. ENERGETICS Acquiring, Storing and Using Energy 5.) CHEMICAL ENERGY Important ATP Dependent Pathways ii. GLUCONEOGENESIS • used when cellular glucose levels are inadequate • Converts a molecule called pyruvate into glucose • requires a great deal of energy so is only used when cells have excess energy available PYRUVATE textbook pg 48

26. ENERGETICS Acquiring, Storing and Using Energy 5.) CHEMICAL ENERGY Important ATP Dependent Pathways iii. TRICARBOXYLIC ACID (TCA) CYCLE • Uses the metabolite Acetyl-CoA, arising from the metabolism of glucose and other energy-rich compounds, to fuel ATP production • Acetyl-CoA is produced by many different pathways (see fig) textbook Fig 2.38 pg 57

27. ENERGETICS Acquiring, Storing and Using Energy 5.) CHEMICAL ENERGY Important ATP Dependent Pathways iv. FATTY ACID OXIDATION • fatty acids are an important fuel for may tissues (e.g. mammalian heart) • sequentially cuts acetyl-CoA off the ends of fatty acids, which can then be used to generate ATP textbook pg 53

28. ENERGETICS Acquiring, Storing and Using Energy 5.) CHEMICAL ENERGY • A cell activates pathways of energy production when it needs energy, but stores energy when it is abundant How do cells “sense” energetic needs? • Pathways like the TCA cycle are sensitive to CELLULAR INDICES OF ENERGY, such as acetyl-CoA. • When acetyl-CoA concentrations are high, storage of energy is favored. Conversely, when acetyl-CoA concentrations are low, energy production is favored.

29. LECTURE SUMMARY • chemical and biochemical processes occurring at the molecular level ultimately influence higher levels of function such as physiology • some of the most important chemical and biochemical processes that influence physiological function involve energy transfer or ENERGETICS. • in the context of biological systems, energy comes in several forms: • 1.) RADIANT ENERGY • 2.) MECHANICAL ENERGY • 3.) ELECTRICAL ENERGY • 4.) THERMAL (HEAT) ENERGY • 5.) CHEMICAL ENERGY • most biologically available energy is stored in the form of chemical energy. Important energy producing pathways include: • 1.) GLYCOLYSIS • 2.) GLUCONEOGENESIS • 3.) TRICARBOXYLIC ACID (TCA) CYCLE • 4.) FATTY ACID OXIDATION • pathways like the TCA cycle are sensitive to CELLULAR INDICES OF ENERGY, such as acetyl-CoA.

30. LECTURE SUMMARY • a lot of material in Chapter 2 was not included in this lecture • only a portion of the SUMMARY and CONCEPT CHECKS at the end of this chapter is relevant to today’s lecture

31. NEXT LECTURE Membrane Physiology (Chapter 2)