BIOL 3151: Principles of Animal Physiology

BIOL 3151: Principles of Animal

Physiology

ANIMAL PHYSIOLOGY

Dr. Tyler EvansEmail: [email protected]: 510-885-3475Office Hours: M,W 10:30-12:00 or appointmentWebsite: http://evanslabcsueb.weebly.com/

mailto:[email protected]

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

UNIFYING THEMES IN PHYSIOLOGY1. Physiological processes obey physical and chemical

laws2. Physiological processes are regulated to maintain

internal conditions within acceptable ranges 3. 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.

4. The genotype is a product of evolutionary change in a population of organisms over many generations

PREVIOUS LECTURE

TODAY’S LECTURE

textbook Fig 2.1 pg 22

• principles of chemistry and biochemistry underlie physiological processes

BASIC PRINCIPLES OF CHEMISTRY AND BIOCHEMISTRY IN PHYSIOLOGY

TODAY’S LECTURE

• chemical and biochemical processes occurring at the molecular level ultimately influence higher levels of function such as physiology

BASIC PRINCIPLES OF CHEMISTRY AND BIOCHEMISTRY IN PHYSIOLOGY

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

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

ENERGETICS• in order to remain in energetic balance, cells must produce

energy at rates that match demand

• e.g. Mammalian heart

• heart cells consume 30 units 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

ENERGETICSAcquiring, 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 ENERGY2.) MECHANICAL ENERGY3.) ELECTRICAL ENERGY4.) THERMAL (HEAT) ENERGY5.) CHEMICAL ENERGY

• different animals have evolved different strategies for acquiring and using energy

textbook pg 23

CHEMISTRYAcquiring, 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 energye.g. corals

most reef-building corals contain photosynthetic algae, called ZOOXANTHELLAE, that live in their tissueszooxanthellae supply the coral with energy, which they then use to fuel their physiology


2.) MECHANICAL ENERGY

• A flying bird uses its wings to produce the mechanical energy required for flight

• A kangaroo uses mechanical energy stored in its legs to hop

textbook pg 23

• energy associated with the motion and position of an object • animals generate mechanical energy during locomotion


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 cause muscle contraction


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)


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 is released than it costs to maintain the gradient

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



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 in the activity of ENZYMES

• ENZYMES are proteins that catalyze (speed up) chemical reactions in cells


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


4.) THERMAL (HEAT) ENERGYEnzymes exhibit a two-phase response to temperature:1. activity increases as a consequence of the of the rate-enhancing effects of

temperature on enzymes.2. at higher temperatures the destructive effects of temperature take over

and rates of activity decline

rate enhancing effects

destructive effects

enzy

me

reac

tion

rate

Temperature (°C)


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


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


4.) THERMAL (HEAT) ENERGY• thermal stability of enzymes in animals from different habitats

What range of temperatures would you expect these crabs to encounter?


4.) THERMAL (HEAT) 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



5.) CHEMICAL ENERGYImportant ATP-Dependent Pathwaysi. 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


5.) CHEMICAL ENERGYImportant ATP Dependent Pathwaysii. 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


5.) CHEMICAL ENERGYImportant ATP Dependent Pathwaysiii. 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)



5.) CHEMICAL ENERGYImportant ATP Dependent Pathwaysiv. 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


5.) CHEMICAL ENERGY

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.

• A cell activates pathways of energy production when it needs energy, but stores energy when it is abundant

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 ENERGY2.) MECHANICAL ENERGY3.) ELECTRICAL ENERGY4.) THERMAL (HEAT) ENERGY5.) CHEMICAL ENERGY

• most biologically available energy is stored in the form of chemical energy. Important energy producing pathways include:

1.) GLYCOLYSIS2.) GLUCONEOGENESIS3.) TRICARBOXYLIC ACID (TCA) CYCLE4.) FATTY ACID OXIDATION

• pathways like the TCA cycle are sensitive to CELLULAR INDICES OF ENERGY, such as acetyl-CoA.

LEARNING OBJECTIVES

LECTURE 2: BASIC PRINCIPLES OF CHEMISTRY AND BIOCHEMISTRY IN PHYSIOLOGY

What are the five forms of energy used by biological systems and provide an example of each?

What are electrical gradients and why are they important for animal physiology?

Draw an enzyme activity curve and explain the two-phase response.

Predict the habitat of a particular organism based only on the enzyme activity curve

Why is Acetyl CoA a suitable energetic sensor?

NEXT LECTUREMembrane Physiology (Chapter 2)

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BIOL 3151: Principles of Animal Physiology