Chapter 1: Homeostasis and Regulation Flashcards
4 Unifying Themes of Animal Physiology
1) it’s integrative. There are multiple levels of organization and it addresses both APPLIED and BASIC questions
2) it obeys design laws: the laws of physics and chemistry
3) Physiological processes are shaped by evolution
4) most physiological processes are regulated by positive and negative feedback
_____ feedback maintains homeostasis, and ____ feedback generates an explosive response.
POSITIVE feedback maintains homeostasis, and NEGATIVE feedback generates an explosive response.
2 Central questions and EXPLANATIONS about animal physiology
1) Mechanistic explanation: “How does this work”: emphasized composition, structure and function
2) Evolutionary explanation:” “How does this become like this?” : emphasizes and loots at the roles of NATURAL SELECTION and selective environmental pressures that contribute to specific functions or structures being studied.
Homologous Traits
seen in 2 different evolutionarily related organisms (related by common ancestry), that have the same BASIC TRAIT but are FUNCTIONALLY different
(ex/ human arms vs wings)
Analogous Traits
similar structures and functions of unrelated species that evolved independently. ex/ birds and insects have WINGS (same function) but they are not related.
Hypothetico-deductive method
the process of creating a scientific theory. Using INduction and deduction
outline the hypothetico-deductive method
1) ask a question about the phenomena of nature
2) propose a bunch of hypotheses to possibly explain the phenomena via INDUCTION
3) use DEDUCTION to design the experiment and observations that test the hypothesis.
4) conduct the experiment
5) refine the hypothesis and desgin the new test
when does a new theory arise?
when a hypothesis is consistently supposed and all the alternative hypotheses have been falsified.
The Krogh Principle and an example
there is an ideal research animal that can be used to study and explore every type of phenomena.
ex/ studying nerves: use an animal with large nerves rather than a mouse. a giant squid with large axons may be the ideal animal
_____ is the father of MODERN physiology
_____ is the father of COMPARATIVE physiology
claude bernard: father of modern physiology
arther crowe; father of comparative physiology
Teleological Approach
method of studying by assuming that organism traits are explained in terms of their purpose in fulfilling a need, without questioning how this outcome is accomplished or evolved.
- there is no “mechanism” or “ultimate/evolution” question
refuting the teleological approach
some features are convoluted and not logical: why would an organism have a design that does not completely fulfill a need?
some features are vestigiaL: they no longer have purposes or fulfills a need, so why is it still in the organism?
Cost Benefit Trade Offs in Terms of evolution
adaptations have consts that negatively impact other adaptations. the largest trade off is energy. the larger structures for protection are made at a cost of reduced speed and flexibility. Many structures an organism has is not FULLY OPTIMAL, but it does balance the energy costs.
___ ___ compares systems of different species utilizing the horizontal approach.
comparative physiology
Why are comparative studies so important?
1) you can learn about the diversity of life
2) comparative studies allows us to determine universal functions.
comparative physiology research is motivated by the ____ principle.
Krogh principle: for any particular physiological process, some speices will have adapated in such a way that it proves an ideal model system for studying that process
biomimicry
the emulation of organismal adaptations by humans to create useful products (ex/ velcro imitates seed-spreading mobility mechanism)
Why are there no complex unicellular organisms?
there is a PHYSICAL SIZE CONSTRAINT that PREVENTS SPECIALIZATION. There are also diffusion limitations that effect the maximum size of a cell. If the size is too large, materials could not spread efficiently to all parts of the cell
4 main cellular functions of life
1) self organiztion
2) self regulation
3) self support and movement
4) self replication
how does a cell self-organize?
uses resources from the enviornmnet to reate the cell. It obtaines energy and raw materials and performs chemical reactions in specialized sequences (organized)
how does a cell self-regulate
maintains self-integrity in the face of disturbances aka maintains homeostasis.
the cell regulates by controlling the exchange of materials between the cell and its surrounding environment. It repairs damage to the cell and corrects deviations in internal conditions
how does a cell self-support and move
has sturctures that give form to specific cell types. Usually involves microfilaments and microtubules that allows or material and vesicle movemnet
how does a cell self-replicate
via mitosis and meiosis, it reproduces to carry on species and to repair damage.
4 main types of tissues
1) epithelial tissue
2) connective tissue
3) muscular tissue
4) nervous tissue
what is a tissue?
groups of cells with similar structure and function
function of epithelial tissues. give two types of epithelial tissues
epithelial tissues: cells that can exchange materials
includes
1) sheet tissues: covers and lines various organs. Serves as boundaries that separate the organism from external environment and from the contents of cavities
2) gland cells: cells that specialize in secretion.
2 types of glands
1) exocrine gland: secrete through ducts to the outside or into a cavity that communicates with the outside (ex/ sweat gland)
2) endrocrine gland: secrete their products directly into the blood stream with no ducts. (ex/ parathyroid hormong)
both glan systems are made of epithelial tissues.
function of connective tissues
connective tissue: a few cells dispersed within abundance of extracellular material to CONNECT, SUPPORT, and ANCHOR various body parts
all connective tissues produce ____ into the extracellular space to facilitate stretching and reecoiling of body structures
elastin
loose connective tissue
attaches epithelial tissues to underlying structures
tendons
type of connective tisse that attaches skeletal muscles to bone
bone
type of connective tissue that gives vertevrates shape, support and protection
blood
considered a connective tissue that transports material around the body
function of muscular tissue
cell groups that are specialized for contraction and force generation.
3 main types of muscle tissue
1) skeletal muscle
2) cardiac muscle
3) smooth muscle
specialization of nervous tissue
cells specialized for inititation and transmission of electrical impulses. typically found in the brain, spinal cord and epithelial linings that monitor the external environment to monitor HR BP and gut contents.
also found in junctions of muscles and glans and effector organs.
a _____ is 2 or more primary tissue types organized to perform a particular function
organ
Define homeostasis
the dynamic steady state in which changes that do occur are minimized by compensatory physiological responses. Animals keep their internal environment around an optimal level wihtin a narrow limit by carefully regulating mechanisms.
_____ coined the term “homeostasis,” but the orginal thought of homeostasis was ____
Walter Cannon coined homeostasis, but the idea started with Claude Bernard (the father of modern physiology)
homeostasis is a _____, ____ , ___-___ process that occurs at the level of the whole _____
homeostasis is a DYNAMIC, REGULATORY , STEADY-STATE process that occurs at the level of the whole ORGANISM
how can cells exchange materials with the external environment if most aren’t even in contact with it?
via the extracellular fluid
2 components of ECF
blood plasma and interstitial fluid
usually, its the ____ layers of cells that accomplish exchanges between the external environment and internal environment
typically epithelial layers
In most animals, macromolecule concentrations, O2 levels, waste products, pH and electrolytes are homeostatically controlled. However, what are superorganisms also able to do?
In adittion to regulating concentrations and levels of various chemicals, superorganisms are also able to regulate social parameters ( termites move in a group)
Regulators:
use internal mechanisms to define a regularly constant internal state.
what is a thermoregulator?
an organism that has internal mechanisms in place to maintain its body temperature.
conformer
an organism whose internal state varies with that of the environment (cold blooded reptiles)
Avoiders
minimize internal variation by completely avoiding environments that could disrupt their homeostasis (ex/ migratory organisms)
enantiostasis
when an organism can maintain its normal function despite the outside environment changing. BUT the organism is NOT in homeostasis
example of enantiostasis
the blue crab. it typically lives in the ocean (that has high salt concentration). But when the tide pulls in, the crab is left in an estuary with LESS SALT CONTENT in the water. the less salt PREVENTS O2 from binding to its hemocyanin (crab version of Hb).
the less salt= less O2 = the crab becomes more acidic.
in order to prevent O2 loss, the crab begins to INCREASE AMMONIA PRODUCTION to INCREASE the PH (DECREASE ACIDITY), allowing more O2 to bind.
thus, the crab gets the needed O2, but it changes its internal conditions. It undergoes the process of enantiostasis.
if the crab was to maintain homeostasis, it would have an internal mechanism in place to prevent any acidity and lack of O2 problems in the first place when it moved to the esturary.
define negative feedback and the two types of negative feedback
negative feedback: a change in a controlled variable that triggers a response that opposes change, driving the variable in the opposite direction of the initial change.
1) unreferenced feedback: imprecise control
2) references negative feedback: negative feedback with a built in set point that gives an ideal state and then shuts off.
3 main components of referenced negative feedback
1) a sensor: detects change and communicates the error signal to the integrator
2) integrator: compares levels of controlled variable to set point and initiates a response to CORRECT THE DEVIATION by sending a signal to the effector
3) effector: restores controlled variable to a SET POINT.
3 Types of possible effectors than can exert an action to correct a deviation
1) antagonistic control: 2 effectors with opposite control (ex/ furnave vs AC)
2) behaviors as effects: specific movment plans to correct a deviation (ex/ avoiders migrate to prevent homeostatic deviation)
3) internal organs: can act as effectors by taking action to relieve deviated varialbe ( usually through hormones)
problems with negative feedback systems
1) overall delayed response: it takes time to relay the message that there is a deviation, and it takes time for the effector to correct the deviation. It also takes time for the effector to be turned off later once the problem has been corrected, resulting in an overshoot.
- many homeostatic process fluctuate due to delay in reponses (ex/ temperature)
2) negative feedback systems are situation specific. They may not work if the animal changes its environment.
How is the delayed reponse problem of negative feedback corrected?
there are anticipations and feed forward systems that can activate the effector before the disturbance ticks of the “sensory set point,” activating the appropriate response in advance of the change. Feed forward systems can also suppress the effector before it overshoots the ideal set point.
ex/ saliva production when you smell food before you even put food in your mouth.
How is the situation specific drawback of negative feedback accounted for?
organisms have phenotypic plasticity that allows for mechanisms to change over prolonged exposure to a new environment. ex/ mammals begin to increase fat stores before the winter comes, so it can maintain homeostasis while the cold temperatures are here.
If an animal cannot exhibit enough phenotypic plasticity so its feedback mechanisms work correctly during an environmental change, what may happen to the organism?
the animal may go into dormancy: a state of GREATLY REDUCED metabolism which occurs when negative feedback systems cannot be modified.
5 frames of physiological changes
1) acute changes: changes that individuals exhibit soon after their environment changes; they are REVERSIBLE (ex/ goosebumps)
2) chronic change: changes that are displayed when an individual has been in the new environment for a longer period of time (ex/ higher BPG levels after being exposed to higher altitudes with less oxygen. Is SLOWLY REVERSIBLE)
3) Evolutionary change: changes that occur by alteraction of gene frequencies over the course of multiple generations and are IRREVERSIBLE
4) Developmental change: programmed physiological change (puberty), and are MODERATELY REVERSIBLE with intervention
5) changes controlled by BIOLOGICAL CLOCKS: repeated change. ex/ fertility, circadian rythym.
what are the frames of physiological change that occurs due to environmental change? What about frames of physiological change that are internally programmed?
environmental change results in:
1) evolutionary change
2) acute change
3) chronic change
internally programmed change involves physiological frames:
1) biological clock
2) developmental change
rheostasis
non homeostatic regulation (variable state)
acclimation?
acclimatization processes that take place in a controlled setting.
2 methods for regulating non-homeostatic change
1) reset systems
2) positive feedback system
what is a reset system?
a method for regulating non-homeostatic change (maintaining rheostasis)
changes the SET POINT of a negative feedback system in a temporary, permanent, or cyclic fashion.
ex/ temporary reset of set point: fever resets the temperature set point so everything now functions at a higher temp while bacteria are being killed off
permanent set point reset; sex hormones during puberty are permanently reset to higher levels in adult hood
cyclic fashion set point reset: hiber nation
how does a positive feedback system regulate non-homeostatic change?
creates rapid change when a condition demands a rapid change from set point. Output is continually enhanced so that the controlled variable continues to move in the SAME DIRECTION of the initial change.
what are intrinsic controls?
controls that are regulated independently by a single tissue for a self serving process.
ex/ increased CO2 in muscles is detected by smooth muscle of blood vessel, and vessel relaxes and dilates to increase blood flow TO THE MUSCLE.
(this process is self serving, and it is regulated by the muslce itself, not the brain)
extrinsic controls. How do they contrast to intrinsic controls?
regulatory mechanisms initiated OUTSIDE an organ to alter its activity. Usually invovles two or more organs, and is governed by the nervous or endocrine system or immune system. There is often a COMMON GOAL, rather than a self serving function that intrinsic controls do.
they also have the ability to OVERRIDE the intrinsic controls (nervous system can cause the muscle to serve a non-self serving function)
Whole body control systems vs support movement systems
whole body control systems regulates and coordinates homeostasis, but support and movement systems are not necessary to homeostasis.
main whole body control systems and main suppot and movement systems
whole body systems:
1) nervous system
2) endocrine system
support and movement systems
1) skeletal systems
2) muscular systems
(also, reproductive systems are also not essential for homeostasis)
When do muscular systemas play a role in homeostatsis even though its a main support and movement system ?
in birds and mammals, muscular system is also involved in thermoregulation.
6 maintenance systems
1) circulatory system for material transport
2) immune system
3) respiratory system for gaseous waste removal
4) excretory systems
5) digestive systems
6) integumentary systems (skin and protection)
