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Animal Physiology Zool 4230 General objectives: 1. Gain factual knowledge 2. Learning fundamental principles, generalizations, or theories
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Physiology is the study of life processes:
Study of physiology Physiology is the study of life processes: · How living systems work, from the molecular level to organ systems and to the whole organism · How the organism responds to physical activities and to the environment around it, whether it is the vacuum of space or the depths of the ocean · How disease can affect living systems · How the genome translates into function both within the cell and the whole organism
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Table 1.4
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Comparative physiology Environmental physiology
Introduction Comparative physiology Environmental physiology Evolutionary physiology
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Figure 1.17 The comparative method
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Figure 1.12 Performance in an oxygen-poor environment
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Migrating Pacific salmon
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Goal- to maintain life Need Nutrients Oxygen Water
Survival need Goal- to maintain life Need Nutrients Oxygen Water Maintain body temperature Atmospheric pressue
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Figure 1.1 The study of physiology integrates knowledge at all levels of organization (Part 1)
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Figure 1.1 The study of physiology integrates knowledge at all levels of organization (Part 2)
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Physiology’s two central questions
Origin– why do modern-day animals possess the mechanisms they have? Mechanism– how do modern-day animals carry out their functions?
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Why do modern-day animals possess the mechanism they have?
The Study of Origin Why do modern-day animals possess the mechanism they have? Products of evolution The study of evolutionary origins reveals the significance of mechanisms Reliance on indirect reasoning– very rarely understood
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Key process of evolutionary origin
Natural selection- increase in frequency of genes that produce phenotypes that improves an animal’s chances of survival and reproduction within the environment Adaptations- aid the survival and reproduction Adaptive significance evolved by natural selection
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Figure 1.4 Structures similar in performance & adaptive significance can differ dramatically (Part 1) anphys-fig jpg
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Figure 1.4 Structures similar in performance & adaptive significance can differ dramatically (Part 2) anphys-fig jpg
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Fitness– link to adaptation Environment– habitat
Natural selection Two basic concepts Fitness– link to adaptation Environment– habitat Biome: problems encounter Design and strategy Behavioral modification
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Environmental components
Stress Biotic– direct and indirect effects of other organisms, e.g. competition Abiotic– physical and chemical Magnitude of fluctuations Long term– tsunami outcome Short term– lunar or daily cycle Resource/energy availability
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Figure 1.9 Fish around Antarctica spend their entire lives at body temperatures near –1.9°C
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Figure 1.10 Butterfly biogeography
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Figure 1.11 A thermophilic (“heat-loving”) lizard common in North American deserts
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Adaptation Adaptation Traits observed– result of selection Natural selection adjusts the frequency of genes that code for traits affecting fitness Short term compensatory changes Acclimation Acclimatization
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Responses to changes in environmental conditions
Avoidance Conformity Regulation Behavior
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Conformity and regulation
Two principal types of relations between an animal’s internal and external environment Conformity/regulation Conformity- an animal permits internal and external conditions to be almost equal Regulation- an animal maintains internal constancy with external variability
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Figure 1.5 Conformity and regulation
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Figure 1.6 Mixed conformity and regulation in a single species
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Advantages and disadvantages of conformity and regulation
Regulation- disadvantage– costs energy Regulation- advantage– permits cells to function independently of outside condition Conformity- disadvantage- cells within the body are subject to change when outside condition changes Conformity- advantage– avoids energy costs of maintaining organization
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Responses to environmental change
Acute response Chronic response Acclimation Acclimatization Evolutionary response
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Figure 1.7 Heat acclimation in humans as measured by exercise endurance
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Figure Marine invertebrates have body fluids similar to seawater in their concentration of salts anphys-fig jpg
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Mechanisms of adaptation
Molecular level Genes/DNA Any changes at the DNA level Changes in protein expression Core of adaptation Anything that controls protein properties and degradation
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Genotype and environmental interaction
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Protein synthesis and degradation
Control of gene expression Intracellular proteolytic mechanisms Degradation may occur In cytoplasm In endoplasamic reticulum Ubiquitin (marker protein)serves as degradation signal
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Six steps at which gene expression can be controlled
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Activation of G protein by extracellular signal
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Interaction of two G proteins with a single cAMP-producing adenyl cyclase, giving both stimulatory and inhibitory pathways
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Extracellular control signals
Growth factor Hormones Neurotransmitters
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Size and scaling Body-size relations are important in making prediction of the species’ physiological and morphological traits. Length, area, and volume Isometric scaling Allometric scaling
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Figure 1.8 Length of gestation scales as a regular function of body size in mammals
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Figure 1.18 Physiological variation among individuals of a species
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Maintaining constancy of internal environment.
Homeostasis Maintaining constancy of internal environment. Dynamic constancy. Within a certain normal range. Maintained by negative feedback loops. Regulatory mechanisms: Intrinsic: Within organ being regulated. Extrinsic: Outside of organ, such as nervous or hormonal systems. Negative feedback inhibition.
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Sensor: Integrating center: Effector:
Feedback Loops Sensor: Detects deviation from set point. Integrating center: Determines the response. Effector: Produces the response.
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Reverses the deviation. Produces change in opposite direction.
Negative Feedback Defends the set point. Reverses the deviation. Produces change in opposite direction. Examples: Insulin decreases plasma [glucose]. Thermostat. Body temperature.
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Negative Feedback (continued)
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Action of effectors amplifies the changes.
Positive Feedback Action of effectors amplifies the changes. Is in same direction as change. Examples: Oxytocin (parturition). Voltage gated Na+ channels (depolarization).
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Confidence in rational ability, honesty and humility.
Scientific Method Confidence in rational ability, honesty and humility. Specific steps in scientific method: Formulate hypothesis: Observations. Testing the hypothesis: Quantitative measurements. Analyze results: Select valid statistical tests. Draw conclusion.
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