Surface Area Grows...

Volume Grows...

Surface Area grows as a square (2 dimensional)

Volume grows as a cube (3 dimensional)

Smaller animals have more surface area to volume ratio

Bigger animals have more volume to surface area ratio

Physiology=Function 

Dynamic: physical-chemical events in time and space 

Proximate (Mechanistic) Cause

Ultimate (Evolutionary) Cause

How does it work?

Ex- warm bodied tuna body temp are higher than ocean temp cuz of countercurrent blood flow

How did it get to be this way?

They are fast swimmers; the warmer the muscle, the greater the power output

Adaptation: beneficial features that enhance the survival of the specie

Homologous: two diff organisms, but have similar trait related by common ancestry

Ex-bird wings and human arm

Analagous: similar structure or function traits, but evolved independently

Ex- bird and insect wings ( similar function, but no common ancestral structure)

phenomena that occur in organisms are explained in terms of their purpose

Exception: Vestigial--> having no useful function 

Adaptations have cost-benefit trade offs

Example?

Seastars produce many embryos (BENEFIT), but they do not protect nor provide much yolk (energy) for them (COST). 

Revers: birds 

Some animals have the same trait, but for one it is useful and for others it is not useful. 

Ex- dog dewclaw

Vestigial genes

Ex- humans cannot synthesize vitamin C, but the we have a nonfunctional gene for a protein to make the vitamin. 

Gene mutated and shut off

Comparative Physiology

August Krogh Principle

For every problem or question in physiology, there is one particular animal or species which can best be utilized to investigate the question (Model Organism)

Ex- Squid: giant axon for neurophysiology

       Fruit Fly: genetics

Convergent Adaptation (Homoplastic)

Phenotypic Plasticity

Similar features in species of different lineages 

         Ex- wings; birds and insects have wings, but are from diff ancestors. 

Similar genotype, but different phenotype due to the influence of the env

      Ex- anole lizards that live in green vegetation are green and those in trees are brown

Cells-->tissues-> organ -> organ system-> organism 

Tissue:

Epithelial, connective tissue, muscle, and nerve

Epithelial: exhange materials and seperate the animal from the external env. (protect, secrete, and absorb)

Connective: structural support

Muscle: movement

nerve: communication, control, coordination

Tissue: groups of cells with similar structure and function

Organ: two or more types of primary tissue organized to perfrom a particular function

Organ System: collection of organs that interact that accomplish an activity essential for survival.

self-organization

self regulation

self replication

support and movement

Homeotherm vs. Poikilotherm

Endotherm vs. Ectotherm

Homeotherm: maintain constant body temp

Poikilotherm: variable body temp

*not perfect term cuz body temp changes like during sleep, etc.

Endotherm: heat comes from within [birds & mammals]

         Ex- humans metabolism produces heat

Ectotherm: heat source comes from without [amphibians & invertebrates]

        Ex- lizard sits out in the sun to obtain heat, not from metabolism cuz its too slow

Claude Bernard homeo-> "similar"

stasis-> "stand or stay" "state"

Walter Cannon: "Constancy of the internal env is the condition of free life"

Internal heat production is imp for mammals. even when its cold, we can move because of our internal heat production unlike the lizard. 

Cells make up body systems--> 

Body systems maintain homeostasis-->

Homeostasis is essential for the survival of the cells

Regulators

Conformers

Avoiders

Regulators: use internal mechanisms to defend a relative constant state

Conformers: internal states varies with that of the env

Avoiders: not capable of internal regulation, but can minimize internal variation by avoiding env disturbances

*lowest energy state

*no energy required to maintain system

*cannot get useful work from system

Ex- Dead body: no food, air, etc required. Cannot move.

*matter/ energy are quantitively stable (constant body temp), but their is a flow of matter/energy thru system (got to eat and muscles have to move to maintain body temp)

*rates of gain=rates of loss (losing heat to env is replaced by internal heat production)

*requires energy input (food or stored energy)

*capacity to do work (move, activity)

Ex- alive body 

[Na] inside < [Na] outside  (energy is required to maintain system- active transport)

When we are just sitting, blood, oxygen, CO2, body temp are constant, but then we exercise and temp rises, heart pumps faster and then that becomes constant, but there was a transition (transient state). 

Control

Regulation

Control: ability to alter variable

Regulation: active stabalization of a parameter at or near some particular value or level (amount, intensity, or concentration)

REGULATION + BALANCE= STABILITY

Controlled Variable: Bath temp

Disturbance: heat loss to env

Effector: Heater

Controller or integrator: thermostat

sensor: thermometer

Sensor: measures the variable being regulated

Integrator: compares teh sensed information with the set point

Effector: device or process that makes the corrective response

Feedback

Negative Feedback

Positive Feedback

Feedback: information about the controlled variable comes back to regulate or change the variable

Negative Feedback: opposes deviations (somewhere you have to have an inversion)

Positive Feedback: reinforces deviations

deviation of controlled variable from set point

ref-bath temp

sign and magnitude

Reduces the delay phenomenom by detecting or predicting an oncoming disturbance before a regulated state is changed. 

The anticipator activatates the appropriate responsein advance of the change before it overshoots the set point. 

Acclimatization System

Acclimation

Mechanisms that alter existing feedback usually over many days to work better in a new situation

Ex- Mammals may inc their hair or fat layer

Upregulation: muscle mass inc. if undergo a lot of activity

Downregulation: muscle mass dec. if very sedentary

Acclimation: acclimatization that takes place in a controlled situation; laboratory. 

one that changes the set point of a negative feedback system, in a temporary, permanent, cyclic fashion. 

Ex: annual hibernation adn many reproductive cycels are additional examples of cyclical resets regulated by internal biological clocks. 

Proportional Control 

vs. 

On-off control

Proportional: input-output change in proportion; compensation response is proportional to disturbance.

On-off: input from controller has to reach a point for the heater (effector) to turn on