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/
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
PREVIOUS LECTURE
UNIFYING THEMES IN PHYSIOLOGY
1. Physiological processes obey physical and chemical
laws
2. 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
TODAY’S LECTURE
BASIC PRINCIPLES OF CHEMISTRY AND
BIOCHEMISTRY IN PHYSIOLOGY
• principles of chemistry and biochemistry underlie physiological processes
textbook Fig 2.1 pg 22
TODAY’S LECTURE
BASIC PRINCIPLES OF CHEMISTRY AND
BIOCHEMISTRY IN PHYSIOLOGY
• chemical and
biochemical processes
occurring at the
molecular level
ultimately influence
higher levels of
function such as
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
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
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
ENERGETICS
Acquiring, Storing and Using Energy
2.) MECHANICAL ENERGY
• energy associated with the motion and position of an object
• animals generate mechanical energy during locomotion
• 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
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
cause muscle
contraction
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)
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 is released than it costs to maintain the gradient
ENERGY
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
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 in the activity of ENZYMES
• ENZYMES are
proteins that
catalyze (speed
up) chemical
reactions in
cells
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
ENERGETICS
Acquiring, Storing and Using Energy
4.) THERMAL (HEAT) ENERGY
Enzymes 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
enzyme reaction rate
rate enhancing effects
destructive effects
Temperature (°C)
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
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
CHEMISTRY
Acquiring, Storing and Using Energy
4.) THERMAL (HEAT) ENERGY
• thermal stability of enzymes in animals from different habitats
ENERGETICS
Acquiring, Storing and Using Energy
4.) THERMAL (HEAT) ENERGY
What range of temperatures would you expect these
crabs to encounter?
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
ENERGETICS
Acquiring, Storing and Using Energy
5.) CHEMICAL ENERGY
Important ATP-Dependent Pathways
i. GLYCOLYSIS:
• pathway that breaks down glucose
(sugar obtained from food) to
produce ATP
GLUCOSE
• 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
textbook pg 49
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
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 energyrich compounds, to fuel
ATP production
• Acetyl-CoA is produced
by many different
pathways (see fig)
textbook Fig 2.38 pg 57
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 acetylCoA off the ends of fatty
acids, which can then be
used to generate ATP
textbook pg 53
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.
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.
LECTURE 2: BASIC PRINCIPLES OF CHEMISTRY
AND BIOCHEMISTRY IN PHYSIOLOGY
LEARNING OBJECTIVES
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 LECTURE
Membrane Physiology (Chapter 2)