Animal Physiology Zool 4230 General objectives: 1.      Gain factual knowledge 2.      Learning fundamental principles, generalizations, or theories

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

Table 1.4

Introduction

• Comparative physiology

• Environmental physiology

• Evolutionary physiology

Figure 1.17 The comparative method

Figure 1.12 Performance in an oxygen-poor environment

Migrating Pacific salmon

Survival need

• Goal- to maintain life

• Need– Nutrients– Oxygen– Water– Maintain body temperature– Atmospheric pressue

Figure 1.1 The study of physiology integrates knowledge at all levels of organization (Part 1)

Figure 1.1 The study of physiology integrates knowledge at all levels of organization (Part 2)

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?

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

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

Figure 1.4 Structures similar in performance & adaptive significance can differ dramatically (Part 1)

Figure 1.4 Structures similar in performance & adaptive significance can differ dramatically (Part 2)

Natural selection

Two basic concepts

• Fitness– link to adaptation

• Environment– habitat– Biome: problems encounter– Design and strategy– Behavioral modification

Environmental components

• Environmental Component– 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

Figure 1.9 Fish around Antarctica spend their entire lives at body temperatures near –1.9°C

Figure 1.10 Butterfly biogeography

Figure 1.11 A thermophilic (“heat-loving”) lizard common in North American deserts

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

Responses to changes in environmental conditions

• Responses to changes in environmental conditions– Avoidance– Conformity– Regulation– Behavior

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

Figure 1.5 Conformity and regulation

Figure 1.6 Mixed conformity and regulation in a single species

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

Responses to environmental change

• Acute response

• Chronic response– Acclimation– Acclimatization

• Evolutionary response

Figure 1.7 Heat acclimation in humans as measured by exercise endurance

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

Genotype and environmental interaction

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

Six steps at which gene expression can be controlled

Activation of G protein by extracellular signal

Interaction of two G proteins with a single cAMP-producing adenyl cyclase, giving both stimulatory and inhibitory pathways

Extracellular control signals

• Growth factor

• Hormones

• Neurotransmitters

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

Figure 1.8 Length of gestation scales as a regular function of body size in mammals

Figure 1.18 Physiological variation among individuals of a species

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.

Feedback Loops

• Sensor: – Detects deviation

from set point.

• Integrating center: – Determines the

response.

• Effector: – Produces the

response.

Negative Feedback

• Defends the set point.• Reverses the deviation.• Produces change in opposite direction.• Examples:

– Insulin decreases plasma [glucose].– Thermostat.– Body temperature.

Negative Feedback (continued)

Positive Feedback

• Action of effectors amplifies the changes.

• Is in same direction as change.

• Examples:

– Oxytocin (parturition).

– Voltage gated Na+ channels (depolarization).

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.