Lecture Notes Flashcards
(130 cards)
1
Q
Acclimation and acclimitization
A
Physiological or biochemical responses that function to keep processes within homeostatic limits even with dramatic changes in ambient conditions.
2
Q
Are organisms in complete equilibrium with their environment?
A
No. This creates gradients which encourages exchanges with the environment and the disruption of homeostasis.
3
Q
Basic model of an enzyme catalyzed reaction
A
E+S –>ES complex–>ES activate complex –> P+E
4
Q
Benefits of thermoconformity
A
- simplicity of various physiological systems
- don’t need systems to monitor environment
- don’t need underlying genetics or energy to production of receptors and systems
- don’t have to dedicate nervous system to thermoreceptors
- don’t need effectors to carry out instructions
5
Q
Brown fat
A
Full of mitochondria. Can uncouple phosphorylation to produce heat. This would result in no proton motive force and proton leak would occur to release energy as heat instead of using it for ATP production.
6
Q
Compare and contrast your cold-stress response with that of an Australian Aborigine. What seemed to be the priority for your response? For the Aborigine’s?
A
My cold stress response would be to vasocontrict and shiver to keep my body temperature up. An aborigine would vasoconstrict to lower the body temperature and conserve energy; would not shiver. The main concern for me would be to keep my body temperature up, for the aboriginie it would be to conserve energy
7
Q
Conformation
A
Temp conforms to the temperatue of surrounds. If it’s constant than the animal’s temp will be constant too. Animals are adapted to temperature. Which means that physiological processes don’t function outside of certain conditions.
8
Q
Conformation change
A
Enzymes need to be able to make a conformational change in order to bind with the substrate to make the product.
9
Q
Costs of being a thermoconformer
A
- habitat constraints; too hot, too cold, too much flux
- dangerous at high or low Tb; tolerance limits
- temperature effects rates of biological processes; could lead to a decrease in efficiency of physiological systems
10
Q
Costs of being a thermoconformer?
A
- habitat constraints: too hot, too cold, too much flux
- tolerance limits: dangerous if too high or low Tb
- temperature effects rates of bilogical process, decreases efficiency of physiological systems
11
Q
Define catalyst
A
Catalyst are enzymes that lower the activation energy of a reaction to allow it to proceed. They are not consumed or permanently changed by the reaction.
12
Q
Describe acclimation of sweating in humans over short-term (days) and ontogenetic time scales.
A
If humans are exposed to high heat for a period of 5-7 days, they will increase their sweating rates, but decreases the concentration of solutes in the sweat. In an ontogenetic time scale, humans lose sweat glands (through degredation) as they develop. Aren’t as sensitive to heat stress as you grow. The proportion of sweat glands lost depends on the enviroment you live in.
13
Q
Describe shivering
A
Short-duration, low-tension, contraction-relaxation cycles. This response requires energy and interferes with locomotion. It also disrupts the insulation layers.
14
Q
Describe the physiological response of a wolf whose foot is exposed to severe cold stress. Compare that with the response we’d expect to observe in you, and in an Inuit.
A
For a wolf, the immediate response is to vasocontrict in the paw and then vasodialate before it gets to freezing in cycles of contriction and dilation in order to conserve energy. In ‘me’ the response would be to vasocontrict in all my appendages in order to keep my core warm and conserve energy. This could cause a decrease in function of appendages. In an inuit, the reponse is to vasodilate and keep appendages at a constant temperatue and functioning. Is very energetically expensive.
15
Q
Discuss how S and modulators can affect reaction rate
A
- increase in S increases rate of reaction
- increase substrate and presence of a negative modulator has no effect on reaction rate.
- decreased substrate and a positive modulator has no effect on reaction rate.
16
Q
Graph showing the difference between a regulator and a conformer
A
17
Q
Ectotherms and acclimation
A
Tuning of preferred temperature to the general habitat Ta conditions. In constant environments this leads to tendency to lose acclimation and acclimitization ability.
18
Q
effector
A
Any structure that helps restore the desired internal condition
19
Q
Enymology
A
Physiology of enzymes
20
Q
Enzyme-substrate affinity
A
Ease of binding of substrate to the active site; ability to bond. The higher the affinity the quicker the reaction will proceed.
21
Q
Epithelial cells and transport
A
Have proteins to regulate transport of ions, water, nutrients, wastes. No molecule can enter or leave body without crossing epithelium. Homeostasis is possible because epithelia control exchange
22
Q
Examples of ontogenetic changes
A
One example is sweat glands. Sweat glands degenerate with growth because you are not as sensitive to heat stress. The amount of sweat glands that degenerate depends on your environment. If you live in the tropics you would have less degeneration. Once sweat glands degenerate the do not regenerate.
23
Q
Explain dTb/dt= -CA(T0-TA)
A
Heat exchange is effected by the thermal conductance, (the rate of heat loss for an organism), surface area of the organism and the difference between the temperature of the body and the temperature of the environment (ambient).
24
Q
Explain Newton’s law of cooling (heat exchange)
A
rate of heat exchange is equal to ease of which heat can be exchanged times the magnitude of the gradient (driving force)
25
Explain the costs of adaptations in terms of ecology and evolution.
Every adaptation comes with a trade off. Regulators are able to live in more broad habitats and are not as dependent on the conditions in their environment. Conformers are able to expend less energy and processes for regulation but they are limited by their environment because their preferred may not exist, and when they are taken out of their enviroment they cannot survive.
26
Homeostasis
Defined as stability in chemical and physical conditions within an animals cells, tissues, and organs despite changing environmental conditions. Kept within a tolerable level (pH, temp, Ca++)
27
How do birds and mammals facilitate evaporative cooling? Is there a drawback to the mechanism(s) they employ?
Gular flutter, beaks open, flap under beak fluttlers. Drawback would be energy?
28
How do ectotherms benefit if they’re able to maintain their body temperature at Tpref? Can you offer a possible explanation for this?
They are able to maximize growth, development, and fecundity. This is because they do not have to spend time and energy to maintain their body temperatures and can allocate energy to growing and reproducing.
29
How do endotherms adjust to long term cold temperatures?
Increase synthesis and release of thyroxine (produced by thyroid and triggered by thyroid stimulating hormone) and prolactin.
30
How do gradients and exchanges relate to homeostasis?
The cells maintain gradients so that they can access substrates that they need in order to maintain homeostatic balances.
31
How do humans acclimate to high ambient temperatures?
Humans respond to heat stress over periods of more than 5-7 days. They increase sweating rates and decrease the solute concentration in the sweat in order to conserve the solutes.
32
How do modulators work?
They work by changing the shape of the active site. Negative modulators inhibit the activity of an enzyme. Positive modulators activate the enzyme.
33
How does a substrate bind to an active site
H bonds, van der Waals, Hydrophobic, etc
34
How does an endotherm maintain its temperature in the TNZ without changing its metabolic rate?
Endotherms make use of blood shunting; which is cheap energetically. When the endotherm is hot it can increase blood flow closer to the skin which allows for more heat loss and cools the animal. When it is cold, it can increase blood flow to the core so that it does not lose as much heat.
35
How does enzyme-substrate affinity affect reaction rates?
Higher affinities allow for higher reaction rates
36
How do thyroxine and prolactin affect LCT?
It lowers the LCT. Increase insulation effectiveness by reducing the thermal conductance of the insulation.
37
How is precise tuning of funtion to ambient temperature beneficial?
Increases efficiency, inceases growth and fecundity and maximizes fitness
38
How is the temperature regulation different for the periwinkle in summer and winter?
In the summer and winter the TNZ is different (lower in the winter months). This is made possible by the production of isozymes.
39
If Ta is relatively constant
1. can fine tune enzymes, physiology systems to work well and maximize efficiency
2. maximizes survival and reproduction (fitness)
40
Importance of driving force in homeostasis
In heat regulation, the temperature gradient is the driving force for an organism to exchange heat with its environment. And the rate of the heat exchange between the environment and the organism.
41
integrator
evaluates incoming sensory information and "decides" whether a response is necessary to acheive homeostasis
42
Intermediate time scale
Longer than the time it takes transcription and translation to occur, but shorter than the lifespan on the organism
43
Isozymes
Enzymes that perform the same function but at different temperatures (at different conditions). This is done by new gene expression for the enzyme. A single aa substitution near the C terminus allows the enzyme to shift optimum temperature.
44
Lock and key model
Enzymes have a high specificity for substrates.
45
Long term time scale
greater than lifespan (evolution).
Example: epigenetics
46
Metabolic disruption
changes the ratios of metabolic products; can impact outputs in huge ways
Alzheimers ration of phosphatidychlorine and phsophatidylethanolamine is different than "normal"
47
metabolic rate
- measure O2 cosumption rate
- indirect measure of energy consumption/production
- reflects overall health and ability of homeostasis
48
negative feedback
effectors reduce or oppose change in internal conditions when a molecule level becomes too high.
49
Newton's law of cooling (heat exchange)
Rate of heat exchange is equal to ease of which heat can be exchanged times magnitude of the gradient. Increased area increases ease of heat loss.
50
Non shivering thermogenesis
Triggered by norepinepherine and epeinepherine. Increases glycolysis and lipoltsis. In humans this increases metabolic rate by 25% over BMR
51
Ontogenetic time scales
during development. An example of this would be sweat glands
52
Osmoconformers
allow concentrations to fluctuate wiht environment. most marine invertebrates are osmoconformers, many freshwater invertebrates.
53
Osmoregulation
Regulation of the concentration, volume, and composition of body fluids. Death is the penalty of this getting outside of homeostatic limits.
54
Phenotypic plasticity
animals in constant environments aren't as good at this. if phenotypic plasticity is not used it an organism can lose it's effectiveness at this.
55
Q10
* temperature coefficient; primarily concerned with energy of activation
* can model immune system, growth rates, muscle strength, info processing
* Q10= (R1/R2)((10/(T2-T1))
* Q10=(rate+10)/(rate T)
56
Regulation
Adjust internal stat to keep within limits that can be tolerated no matter the external conditions. They can do this by processes such as panting and shivering. Limits to this occur if it is too hot or too cold.
57
Role of epithelium
Interface between internal and external and the key to acheiving homeostasis. THey are responsible for forming an internal environment that can be dramatically different from external environment. This allows internal conditions to be maintained at relatively constant levels.
58
Role of regulation and feedback
- have monitors of homeostasis and can quickly modify if something changes
- each system has a set point; target range of values for a controlled variable
59
Sensor
structure that senses some aspect of external or internal environment
60
Temperature compensation
ability to keep metabolism and homeostasis constant using what's already in the cell
61
The form of energy that moves in response to a temperature gradient?
Thermal conductance of kinetic energy. Heat.
62
Two approaches to acheiving homeostasis
conformitiy and regulation
63
UCT and sweat
When we overheat we sweat. This requires energy because you have to produce the sweat in your sweat glands. This requires the taking up of water and removal of useful solutes to give to the body. This causes a dramatic increase in cardiac output (increased hr and strength of contraction) This also requires energy and increases metabolic rate.
64
What are some benefits to being a thermoconformer?
- If Ta is relatively constant; it adds simplicity because do not need receptors to maintain it
- don't need to dedicate parts of your nervous system to moinitor data from thermoreceptors
- don't need parts of your brain to issue instructions detailing appropriate response
- don't need effectors that will carry out instructions
65
What are the consequences of rhabdomyolysis?
Leakage of ions. Especially K+ in serium, and also leakage of myoglobin. This leads to renal damage and failure.
-Decreased ATP production causes the influx of Ca++ into the muscle fibers which increases protease activity, increases phospholipase activity, and increases production of reactive oxygen species (free radicals)
66
What are the consequences of star fish being in the Baltic sea?
1. look sickly, slimy, puffy
2. decreased growth rate
3. decreased immune response to infection
4. decreased metabolic rates
5. sterile
This is all due to the fact that their body fluids are dilute.
67
What are the costs and benefits of being an osmoconformer?
- It is beneficial because organisms do not have to allocated resources and energy to maintain body fluids.
- It is cosltly because if it cannot be maintained by the environment then the organism will die once they get outside of homeostatic limits.
68
What are the costs of being a thermoconformer?
Have habitat contraints because the conditions can exceed tolerance limits. Suitable Ta may not be available at all. Decreased efficiency in physiological systems.
69
What are the three contributors to homeostatic systems?
Sensors, integrators, effector
70
What does DIC stand for?
Disseminated intravascular coagulation
71
What does enzyme modulation depend on?
Enzymes ability to change shape
72
What happens in muscle fibers during rhabdomyolysis?
Production of ATP decreases. This causes and increase in Ca++ in the cell. Which increases protease activity, increases phospholipase activity, and increases production of reaction oxygen species (free radicals)
73
What is an enzyme?
Protein that is responsible for helping a reaction occur. Usually caused by a conformational change.
74
What is a poikilotherm?
It is a temeperature conformer. When the ambient temperature changes, its "response" is to allow body temperature to change as well.
75
What is a homeotherm?
It is a temperature regulator. When the ambient temperature changes it reponds by regulating its temeperature. They have perfect regulation within limits.
76
What is flux?
Constantly changing, flowing in and flowing out. Exchanges with environment are always happening and cells are adjusting and changing their responses to it.
77
What is homeostasis?
Maintenance of constant internal conditions with in limits conducive to proper physiological function.
78
What is meant by modulation?
regulation of catalytic activity
79
What is meant by the term homeostatic parameter?
-the things being maintained with in limits --body temperature, pH, electrolytes, plasma, glucose, CO2, O2
80
What is meant by the term phenotypic plasticity? How is it adaptive? Does it impose any ecological/evolutionary costs on organisms? Cite an example to support your point
Phenotypic plasticity involves the ability to acclimmate. It is adaptive because it allows organisms to be able to adjust to their environments in changing conditions. It does impose a cost because animals in constant environments lose the ability to acclimate.
81
What is piloerection and what is its role in thermoregulation?
Piloerection is the contraction of muscles on hair follicles to either pull hair or feathers closer or further away from the body to either heat or cool.
82
What is rhabdomyloysis?
Breaking open of muscle fibers
83
What is the BMR?
The basal metabolic rate. It is the minimum cost of keeping alive.
84
What is the difference between competitive and non competitive modulators?
Non competitive modulators bind to a modulation/regulatory site of an enzyme. Competitive modulators bind to the active site of an enzyme.
85
What is the effect of thyroxine and prolactin?
Enter cells and stimulate hormone expression of genes involved in metabolic function (upregulate metabolic genes). Increase rates of enzyme catalyzed reaction and increase rate of metabolic heat production.
86
What is the importance of enzyme modulation for cells?
Cells require certain levels of products, and too much can become toxic to cells. Enzymes need to be regulated in order to maintain homeostasis and the desired cell conditions.
87
What is the law of Mass action? And relevance to enzymes.
The amount of substrate or product dictates what happens to the reaction and reaction rate. High substrate concentrations drive the reaction forward and increase the rate. High levels of product can cause the reverse reactions to occur. Higher levels of substrate make binding to the enzyme happen more frequently and will increase the rate of the catalyzed reaction.
88
What is the LCT?
The lower critical temperature. This is the temperature where your metabolism increases in order to produce heat to keep you warm.
89
What is the mechanism that allows the periwinkle to acclimate?
The periwinkle can acclimate because it has isozymes that lower the LCT for the winter months by allowing enzymes to function at lower temperatures
90
What is the name of the hormone that mediates acclimation of endotherms to temperature changes in the seasons?
Thyroxine and prolactin (thyroxine if just asked for one would be my guess)
91
What is the only heat-dissipation option available to endotherms when exposed to high ambient temperatures? Why does it work to dissipate heat?
Sweat. When the water evaporates off of the skin it allows heat to dissipate
92
What is the relevance of enzyme function to homeostasis?
Enzymes can be used to keep internal conditions constant because they are susceptible to regulation based on the concentrations of substrates, products, and other regulators in a cell. (Their performance can also be affected by temperature and pH)
93
What is the term we apply to the response exhibited by the periwinkle to changes in temperature over immediate time scales?
Thermocompensation. Ability to maintain homeostatic limits over a short period of time and temperatures
94
What is the thermal neutral zone?
This is the range of temperatures where the metabolism is not as effected by the temperature and is able to keep the temperature and metabolic rate in a normal range.
95
What is UCT?
The upper critical temperature. This is when your metaboism increases to cool you down.
96
What other processes (other than enzyme catalyzed reactions) exhibit the Q10 response?
immune response, ATP synthesis, growth rates, muscle strength, information processing
97
What role did enzyme-substrate affinities play in the ability of the periwinkle to survive drastic changes in temperature?
They are able to change their E-S affinities. At temperatures from 20C to 35C have lower substrate affinity, and 0-10C has higher affinity.
98
What sets the LCT?
The temperature at which the heat being lost exceeds the heat being produced.
99
What stabilizes protein (enzyme) tertiary structure?
1. disulfide bridges- covalent, and strong 2. h bonds- electrostatic and weak 3. hydrophobic or hydrophillic interactions 4. other electrostatic interactions
100
What would we observe in a mammal suffering from DIC?
- increased body temp disrupts function of proteins in endothelial cells lining the blood vessels.
- Irritation of endothelial cells activates coagulation cascade and produces fibrin clots. RBCs get trapped in these.
- activation of coagulation cascade leads to fibriholysis that breaks down the clot at the same time. Balance of this and clot forming determines size and persistence.
- During DIC, coagulation factors would be exhausted.
101
What's the problem with star fish not osmoregulating?
The north sea has a NaCl concentration of 3.5%. Starfish in water with higher concentrations than this will dehydrate, and star fish in water with lower concentrations will water overload. In the Balitic Sea the concentration is 1.0-2.5%. The star fish drift here when they are larva.
102
When does DIC occur and what is the result of?
It occurs during heat stroke and results from loss of control of body temperature regulation.
103
When we speak of physiological adaptation over intermediate time scales, what sets the lower limit for the time scale?
Intermidate is longer than transcription and translation but shorter than lifespan
104
Where is thyroxine produced and how is it regulated? What are the consequences of thyroxine release?
Thyroxine is produced in the thyroid and it is regulated by the changing in season. If the organism is opporating under its lower critical temperature, thyroxine is released to lower the temperature limit by increasing metabolic rates through the increased expression of metabolic genes. Metabolic genes increase the rates of enzyme catalyzed reaction and heat production. It also increases effectiveness of insulation by reducing thermal conductance.
105
Which term is the ease with which heat can leave or enter an organism?
thermal conductance; C
106
Why are poikilotherms at the mercy of their environment?
Poikilotherms body temperature varies with the enviroment and it's constantly changing; no thermoregulation. Have to be able to function over a larger range of temperatures.
107
Why do enzymes depend on weak electrostatic interactions for their structural stability
Need to be able to make conformational changes by breaking and making those weak bonds.
108
Why is Ca++ important?
It is a second messenger -too much Ca++ can be hyperactive and toxic to the cell
109
Why is homeostasis important?
- Temp, pH, etc have dramatic effect on structure and function of enzymes (most function best under narrow range of conditions)
- temperature affects membrane permeability and solute diffusion speed
- homeostasis allows molecules, cells, tissues. etc to function at optimal levels
110
Ectotherms
behaviors to adjust rate of heat gain and loss from environment. microhabitat selection. Spend a lot of time and energy regulating body temp
111
endothermy
biochemical and physiological processes to regulate body temperature. metabolic behaviours play a role too
112
adaptation
trait that increases or maximizes fitness in a given set of environmental conditions (trait=phenotypic trait)
113
Shivering
short, low tension, contraction-relaxation cycles. Requires energy, interferes with locomotion, disrupts insulation layers
114
epithelial cells and transport
regulate transport and exchange; makes homeostasis possible. This is important because enzymes function at specific conditions
115
Thyroxine and prolactin
* increase expression of metabolic genes; increase rates of enzyme catalyzed reactions
* LCT is lower after adjusting for thyroxine
* increase insulation effectiveness by reducing thermal conductance
116
What happens is ectotherm's habitat allows them to acheive preferred temperature?
* maximizes growth
* advantages in the predator prey system/model
* higher fecundity
* can protect territory/young better
117
Naked mole rats
* no insulation
* small
* no thermal neutral zone
* can't regulate temperature without expending energy
* burrows have almost constant temperatures
118
artctic fox
* have really efficeint thermal regulation; does not require energy output (shunting and piloerection)
* have really effective insulation
* rarely ever cold stressed
119
habitat conditions
can drive and constrain evolutionary derived responses to temperature and stress and opportunities
120
In constant environment
acclimation is lost; suggests it is costly because evolution selects against it
121
Enzymes must be capable of conformation change in order to
respond to modulators and activate E-S complex
122
Immediate time scale of responses
* limits set by: time required for transcription and translation
* example: temp comensation of periwinkle
* how it works: ES affinity changes allow periwinkle to keep metabolic rate (VO2) within homeostatic limits in spite of large changes in its body temp
123
Intermediate time scale of responses
* lower limit: time required for t and t
* upper limit: life span of organism
* example: temperature acclimaztion in periwinkle
* how it works: seasonal production of isozymes shifts temp compensation plateau interval so that it corresponds with the ambient temperature conditions in different seasons; metabolic rate stays within homeostatic limits in different seasons
124
long term time scale of responses
* lower limit: life span of organism
* 1. general correspondence of preferred body temp with habitat thermal conditions
* 2. loss of acclimation ability in constant temperature habitats
* how it works: ectotherms reduce the cost of thermoregulation or acclimation ability by making changes over evolutionary time
125
the fact that most organisms thermoregulate if given the opportunity implies that
the ecological costs of thermoconformity can be severe
126
a comparison of thermobiology of ectotherms or endotherms from constant and variable temperature environments suggest that
the ability to acclimate is ecologically slash evolutionary costly
127
the purpose of superimposing a q10 effect graph on the graph of a summer periwinkle's met response to chnaging temp was to
give us a null model with which to compare our experimental data
128
What is happening in the TNZ zone physiologically and or biochemically
* the "squirrels" metabolic rate is at the minimum value that is compatible with staying alive (bmr)
* the squirrel is adjusting piloerection and peripheral vasodilation to regulate Tb with minimal energy expenditure. as Ta drops, piloerection activity increase; increased insulation effectiveness. and peripheral vasoconstrictio pulls more blood awat from the body surface; decreased heat losses
129
what is happening in the LCL zone physiologically and or biochemically
At and below LCL first non-shivering thermogenesis, then shivering kick in to increase heat production. this is necessary to offset the increased heat losses as the gradient between body temperature and ambient temperature increases
130
