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What are the 2 central questions in the study of physiology?
- What is the mechanism by which function is accomplished.
- How did the mechanism come to be?
are the 5 timeframes over which physiology changes? Which of these are
internally programmed?Be sure you understand the difference
between acute vs chronic/compensatory changes.
- Acute changes, chronic changes, evolutionary changes,
- developmental changes and changes controlled by periodic biological clocks.
- Developmental changes and changes controlled by periodic
- biological clocks are internally programmed.
. How and why does
oxygen availability change with depth (see Fig. 1.14)? Give an example for how
aquatic animals cope with low levels of dissolved oxygen (hypoxia).From a
medical standpoint, when might humans experience hypoxic conditions?
- Oxygen availability changes with depth due to the lack of
- mixture of surface and deep layers. This is due to heat from the sun creating
- warm and cold layers.
- Aquatic animals cope with hypoxia by taking inhaled O2
- across well-vascularized mouth linings or lung like structures.
- A person experience hypoxic conditions when they are at high
Define non-adaptive evolution and describe the relationship between
non-adaptive evolution and genetic drift. Can you think of an example of a
trait that is nonadaptive?
- Non-adaptive evolution is when a allele is lost by chance
- causing the population to lack alternative alleles which lower survivability.
- Non-adaptive evolution is a scenario for genetic drift where
- chance assumes a predominant role in alternating gene frequencies.
. What are the 3 main response options for organisms facing
global climate change (GCC)?
Flexibility in Performance
What do comparative physiologists study and why is it
relevant for understanding how species will respond to environmental change?
- Comparative physiologist study the tolerance of organisms to
- environmental change and the underlying mechanisms that define the limits or
- thresholds of physiological capacity.
- Knowing where an animal exist today within its tolerance
- threshold and to what degree predicted climate change will shift this position
- will help determine which species is most vulnerable.
What must comparative physiologists understand in order to
forecast how animals will fare in the face of GCC?
- Mechanism that species can use to adjust their
- physiology to changes in the environment.
- How these mechanism might contribute to
- compensatory responses to GCC drivers.
- Trade-offs regarding these mechanisms especially
- in a multiple stressor situation expected in GCC scenarios.
Give an example for how temperature affects each of the
- protein stability: Temperature change over an
- evolutionary timescale results in the development of orthologous enzymes that
- function efficiently under specific habitat temperatures.
- cellular membranes: Temperature disrupts
- membrane fluidity which affects process on the membrane. Cells increase or
- decrease saturation of the phospholipids in order to have stable membrane.
- organismal level processes: Consistent high
- temperatures results in decreases activity, growth and reproduction due to its
- affect on aerobic capacity.
- is the maximum velocity at which a saturated
- enzyme-catalyzed reaction converts substrate to product.
- is the turnover number which is the number of
- substrate molecules converted to product per second by each enzyme molecule
- when saturated.
- is the half saturation constant which is the
- substrate concentration required to attain one-half of the maximal reaction
- Physiological substrate concentration is usually
- not saturated because they will eventually use up the surrounding substrate.
1. Icefish have
white blood! Is the loss of blood hemoglobin adaptive? Describe the
evolutionary pressure that may have led to the loss of hemoglobin and how this
may have occurred at the genetic level.
- The loss of hemoglobin is a non-adaptive
- trait it is a consequence of genetic drift where the allele was lost by mere
1. How can
phylogenetic relationships be used to understand the loss of functional genes?
Does this information tell us whether the loss of hemoglobin was advantageous?
Why or why not?
- Phylogenetic are used to determine whether the
- loss of a functional gene occurred once in a common ancestor or occurred
- several times in a phylogenetic tree. The information does not indicate if the
- loss was advantages because it does not help determine the adaptive
does it mean for an animal to enter the postgenomic era?
- The time after the genome of an animal has been
- fully sequenced.
describe the usefulness of knockout genes, forced over expression, and RNAi to
the study of physiology.
- These three strategies are used to
- clarify gene function. In the postgenomic era of a species, a scientist may
- want to what specific protein came from a targeted sequence. They can use these
- strategies to find the protein and annotate the gene sequence.
1. We tend to think that each expressed gene
has a particular effect on an animal’s phenotype. Why, therefore, if a gene is
knocked out by genetic engineering methods, is the consequent change in an
animal’s phenotype not necessarily a direct reflection of the gene’s effect?
For example, how is it possible to knock out a gene that in fact has a
phenotypic effect and yet not, in some cases, see any measurable change in an
animal’s overall ability to function?
- The organism may
- have physiological alterations that enable it to compensate for the loss of the
- protein. In the example in the book, the mouse was able to compensate for the
- loss of myoglobin by having more capillaries in its heart and increased blood
1. Gene expression
often follows a rhythm, e.g., over a 24 hours cycle or across tidal cycles in
intertidal animals. Why might this be?
- The organism needs different proteins
- depending on its environment. In order to be more efficient, the animal might
- need a different set of proteins when it is exposed under the sun opposed to
- when it is submerged.
1. Compare a
top-down vs a bottom up approach to the study of physiology.
- In the top down approach, the initial
- questions begin at the level of animal functions. As the study continues the
- scientist ask questions relating to lower levers of biology such as tissue
- function, tissue-specific proteins, and finally genes. The bottom-up approach
- works the opposite way and begins by knowing the genes present and asks about
- the protein that comes from the gene.
1. Suppose you carry out genomic,
transcriptomic, and proteomic studies on a single tissue. What type of
information would you obtain from each sort of study? For understanding
physiology, what are the uses and shortcomings of each type of information?
- Genetic sequences are made available
- from the study of genomics which can be used to find the evolutionary origin of
- a specific gene. A shortcoming would be from the fact the each individual of a
- species has a unique genome.
- In this area of study, the indication that a gene is being currently expressed
- can be determined by analyzing the mRNA that is being generated in the body.
- This useful in determining which gene is being unregulated when the individual
- is performing a task or is in a specified environment. The shortcoming is that
- the concentration of mRNA is very loosely correlated to the concentration of
- This study is useful in finding the sequence and structure of a protein that
- the tissue is synthesizing. This study helps narrow down the genes that are
- being expressed for that protein. Its shortcoming is that non-protein molecules
- are left out of the study.
- Metabolomics: This study focuses on the small molecules with lower
- molecular weight such as sugars, amino acids, and fatty acids. This is useful
- in determining the metabolic pathways of a cell. A shortcoming is that there is
- a mixing of cell compartments when retrieving a sample for analyzing. More
- research then required to conclude the study.
Indirect calorimetry measures an animal’s metabolic rate by meansother than quantifying heat and work
(1) measuring an animal’s rate of respiratorygas exchange with its environment (termed respirometry) and (2)measuring the chemical-energy content of the organic matter thatenters and leaves an animal’s body (the material-balance method).4
respiratory exchange ratio (R) rq
moles of CO produced per unit timemoles of O consumed per unit time
What is metabolism
- the subject of this chapter, is the sum of the processes by
- which animals acquire
energy, channel energy into useful functions, and dissipate
energy from their bodies
of the problems with this method is that animals are not always burning
glucose, and there is a different amount of heat produced depending on whether an
animalis consuming carbs, proteins or lipids (or a mixture of all three). Why
is this problematic?
An animal’s recent diet often does not provide accurate insightinto the foodstuffs its cells are oxidizing, because animals storeand interconvert foodstuffs. We can determine the foodstuffs thatcells are oxidizing only by looking at indices of cellular function. Oneuseful index of this sort is obtained by simultaneously measuringboth CO2 production and O2 consumption and taking their ratio
is the RQ value sometimes difficult to interpret?
Unfortunately, R values that are not close to 1.0 or 0.7 are oftendifficult to interpret. For example, if an animal has an R value of 0.8,a researcher cannot simply conclude that its cells are catabolizingproteins, because the catabolism of a mixture of carbohydrates andlipids (or of all three foodstuffs) could also produce an R value of0.8. The potential for ambiguity stems from the fact that althoughthree unknowns exist (the proportions of the three foodstuffs beingoxidized), the R or RQ value encompasses only two knowns (O2consumption and CO2 production). The ambiguity can be resolved,but only by measuring additional indices of cellular function besidesO2 consumption and CO2 production.
What is another indirect method for measuring metabolic rate besides
respirometry? How does this method work?
materialbalance. To apply the method, one measures the chemical-energycontent of all the food an animal eats over a period of time, as wellas the chemical-energy content of the feces and urine eliminatedover the same period.7 Subtracting the energy content of the excretafrom that of the food then gives an estimate of the animal’smetabolic rate. The logic of the method is straightforward: Anyenergy that an animal ingests as chemical energy, but does notvoid as chemical energy, must be consumed.
why the mouse would be likely to die sooner if
these animals could not find any food and thus had to live on their fat
I has a higher basal metabolic rate
smaller mammals have low surface area to volume tto the lose heat faster
weight-specific metabolic rate
rate per unit ofbody weight, termed the weight-specific metabolic rate, and plot itas a function of body weight.
standard metabolic rate (SMR
poikilotherms(ectotherms), animals that allow their body temperatures tofluctuate freely with variations in environmental temperature, suchas amphibians, molluscs, and most fish.
basal metabolic rate (BMR)
standardized measure ofmetabolic rate that applies to homeotherms, animals that physiologicallyregulate their body temperatures, such as mammals and birds.
specific dynamic action (SDA),
This increase in metabolic ratecaused by food ingestion is known as specific dynamic action (SDA),the calorigenic effect of ingested food, or the heat increment of feeding
M = aWb
likelihood that an enzyme will form a complex with the substrate during a
collision is called the
- enzyme‒substrate affinity.
2 ATP, 2 pyruvate, 2NADH2, 2H+
ATP, 2NADH2, 2FADH2
e- transport chain
inner mitochondrial membrane
- uses e- and pumps H+ intermembrane space
- Reducing agents NADH FADH
inner mit membrane
- no o2 needed
- Environmental hypoxia
- Functional anoxia
- lactate , NAD+
- regenerates NAD+ for glycolysis
non-proportional relationships between body size and physiological process