Chapter 1
Define: Homeostasis "homeo" = ___________ "stasis" = ________ or ____________
"homeo" = similar "stasis" = state or condition
What are the 3 components of all control systems?
(1) Input signal (2) Integrating center {integrate, to restore}, that integrates incoming information and initiates an appropriate response (3) Output signal that creates a response.
What are examples of emergent properties in chemistry and biology?
*Chemistry (2 examples)* 1. The taste of saltiness is a property of NaCl but is not a property of sodium or chlorine. Thus, saltiness is an emergent property of NaCl. 2. The properties of water (H2O) are different from hydrogen or oxygen on their own. *Biology (1 example)* 1. The heart is made up of heart cells. Pumping of blood by the heart is an emergent property of the whole heart. An individual heart cell cannot pump blood on its own.
What are the similar words for teleological and mechanistic?
*Teleological:* Ultimate (what is the reason, evolutional fitness consequence of having this particular trait) *Mechanistic:* Proximate (an explanation as to how something occurs)
What are the 3 things that will occur to help increase the blood pressure to regulate a person experiencing hypovolemic shock?
1. Cardiac output increases (helps raise blood pressure) 2. Certain blood vessels vasoconstrict (helps to increase the blood pressure) 3. The kidney produces less urine (prevents the blood volume from decreasing too much)
EXAMPLE OF LOCAL CONTROL
A decrease in [O2] in tissue leads to relaxation of the muscles in the wall of a blood vessel, causing an increase in the diameter of the blood vessel, leading to an increase in blood flow, helping to increase the [O2]. This is a type of homeostatic mechanism (that is locally controlled) to would help to maintain the O2 tissue levels at an appropriate value.
Atoms and molecules A. Chemistry B. Molecular biology C. Cell biology D. Physiology E. Ecology
A. Chemistry
Why can humans produce concentrated urines? (Explain) A. Teleological question B. Mechanistic question
A. Teleological question The same scientist may also note that humans have been able to inhabit some of the most arid environments on earth. Thus, he or she might guess that the reason "why" humans are able to produce concentrated urine is that it helps them survive in very dry areas. This type of reasoning is called teleological.
________ is not a regulated variable because it is not directly monitored by the body. A. Blood pressure B. Heart rate C. Blood glucose levels
B. Heart rate
Molecules, cells, and tissues A. Chemistry B. Molecular biology C. Cell biology D. Physiology E. Ecology
C. Cell biology
Give an example of compartmentation.
Cell membranes separate cells from the fluid surrounding them and also create tiny compartments within the cell called organelles. This allows for different processes to occur in different compartments that all make up the cell.
Define: Systemic changes
Changes throughout the body).
(T/F): Living organisms do not *need* energy.
False; they do *need* it
How do organisms maintain an internal stability?
Homeostasis
What does a molecule's function depend on?
Its structure and shape
Define: Homeostasis
The internal environment of the body is maintained relatively constant. (The maintenance of a relatively stable internal environment.)
What does it mean when we say that physiology is an integrative science?
There are two reason: 1. It means that in order to understand a physiological phenomenon it is often necessary to learn about the phenomenon at multiple levels, from molecules, to cells, to tissues, to organs, etc. 2. The organ systems of the body do not work in isolation. The proper function of the body involves the integration (coordination) action of different organs of the body.
What is the set point with a positive feedback loop?
There is no true set point.
Systemic changes require (short/long)-distance signaling.
long
What does "hypo" mean?
lower
In addition to E coming into our system to live, we need materials in the form of ____________-.
nutrients
What are the two general groups (according to their origin) that diseases fall into?
1. Internal failure of some normal physiological process 2. Failure due to some outside source.
If the body fails to maintain homeostasis of the critical variables listed by Walter Cannon, then normal functions are disrupted and what can happen?
A disease state, or pathological condition {pathos = suffering}, may result.
In the aquarium example (Fig. 1.10), what keeps the heater from sending the temperature up to, say, 50 °C?
A feedback loop, where the response "feeds back" to influence the input portion of the pathway. Turning on the heater increases the temperature of the water. The sensor continuously monitors the temperature and sends that information to the control box. When the temperature warms up to the maximum acceptable value, the control box shuts off the heater, thus ending the reflex response.
________ is a regulated variable because blood pressure is directly monitored by the body. A. Blood pressure B. Heart rate C. Blood glucose levels
A. Blood pressure C. Blood glucose levels
The response is restricted to the region where the change took place. A. Local Control B. Reflex Control
A. Local Control
Why do red blood cells transport oxygen? (Explain) A. Teleological question B. Mechanistic question
A. Teleological question "Because cells need oxygen and red blood cells bring it to them."
The target is the same as the effector (which is an organ or muscle that produces a response in the body) like the pancreas producing insulin. A. Response loop B. Feedback loop
B. Feedback loop
How are people and animals are able to move to other places in the world (Africa or Antarctic) and be able to keep their internal environment around 37°C.
Because we have homeostasis
A glucose steady state is maintained how?
Due to the continual influx of glucose and/or materials that can be transformed into glucose through the intake of food.
Organisms, population, ecosystems, biosphere A. Chemistry B. Molecular biology C. Cell biology D. Physiology E. Ecology
E. Ecology
What type of control is the simplest form of control?
Local
What are the levels of (Na+), (Cl-), and (K+) in the ECF?
Na+ = high Cl- = high K+ = low
What are the levels of (Na+), (Cl-), and (K+) in the ICF?
Na+ = low Cl- = low K+ = high
The amount of Na+ that is lost from the body by excretion (urine and sweat) must be offset by ?
Na+ intake (dietary intake) by absorption in the intestines.
What does the "law of mass balance" say?
That if the amount of a substance in the body is to remain constant any gain must be offset by an equal loss OR any loss must be offset by gain.
Define: Physiology
The study of the function of the body.
(T/F): Homeostasis involves elaborate physiological processes that have evolved to keep the ECF composition relatively stable.
True
(T/F): In science, structure and function are closely related.
True
(T/F): Information flow coordinates body functions.
True
(T/F): Local control is not effective for causing systemic changes.
True
What is the formula for the mass flow rate of a substance?
[substance] × volume flow rate
Most cells in our bodies (are/are not) very tolerant of changes in their surroundings.
are not
What is hypovolemic shock due to?
rapid blood loss/decreased blood volume
What is diabetes mellitus?
A metabolic disorder characterized by abnormally high blood glucose concentrations.
How can humans inhabit some of the most arid places on the earth? (Explain) A. Teleological question B. Mechanistic question
B. Mechanistic question For example, how does a person live in an arid environment with limited access to water, conserve water. What mechanisms is used by their kidneys to make concentrated urine; thereby conserving water?
Molecules and cells A. Chemistry B. Molecular biology C. Cell biology D. Physiology E. Ecology
B. Molecular biology
Any long-distance pathway that uses the nervous system, endocrine system, or both is called ____________. A. Local Control B. Reflex Control
B. Reflex Control
Why is a regulated blood pressure so important?
Because we need to force blood through the various organ systems (perfusion); when the blood goes thought the various capillaries within an organ.
Who defined homeostasis as a relatively constant internal environment?
Claude Bernard
Who said this? "The constancy of the internal environment is the condition for a free and independent life."
Claude Bernard
The concept of a relatively stable internal environment is attributed to the French physician __________________ in the mid-1800s. During his studies of experimental medicine, he noted the stability of various physiological functions, such as?
Claude Bernard -body temperature -heart rate -blood pressure.
What happens when the ECF composition varies outside its normal range of values?
Compensatory mechanisms activate and try to return the fluid to the normal state.
(Excretion/Secretion): tears, feces, urine, carbon dioxide, and sweat.
Excretion
______________ is defined as the elimination of material from the body, usually through the urine, feces, lungs, or skin.
Excretion
(Excretion/Secretion) is the removal of material from a living thing while (excretion/secretion) is the movement of material from one point to another.
Excretion; secretion
(T/F): To maintain constant level, output does not have to equal input.
False; it does
(Most/Some) cells of multicellular animals do not tolerate much change. They depend on the constancy of __________________ to maintain normal function.
Most; extracellular fluid
What is the purpose of compartmentation?
The internal division of a cell, tissue, organ, or the body into different compartments allows for isolation and specialization of function to different areas.
Define: Tidal volume
The volume of air that is inhaled in one breath.
Since structure and function are closely related, is compartmentation a part of this idea? Explain.
Yes, because it is how something is divided up into different compartments.
For multicellular animals, the internal environment of the body is the watery internal environment that surrounds the cells, called _________.
extracellular fluid (ECF) {extra-, outside of}
In positive feedback, the response sends the regulated variable even (closer to/farther form) its normal value.
farther from (It initiates a vicious cycle of ever-increasing response.)
In a ______________________, the response reinforces the stimulus rather than decreasing or removing it.
positive feedback loop
Recall that a reversible chemical reaction is in an equilibrium state when?
the rate of the forward reaction equals the rate of the reverse reaction.
What are the steps/integration of function across many levels of organization?
*Atom* (smallest unit or particle of life) > *Molecules* > *Cells* > *Tissues* (cells that are grouped together having a common function) > *Organs* (i.e. muscles made up of nerves, blood vessels) > *Organ systems* (i.e. the entire gastrointestinal system - mouth going al the way down the body to help absorb food) > *Organisms* > *Population* (of one species) > *Ecosystem* (of different species) > *Biosphere* (living beings interacting with inorganic matter)
The idea of homeostasis was derived from what properties?
-Temperature -Salinity -pH -osmotic concentration (and more)
What are the two categories that reflex control can be broken down into?
1. Response loop 2. Feedback loop
What are the two type of concept maps used?
1. Schematic representation 2. Physiological process
What are the two fundamentally different types of questions that are often asked in science?
1. Teleological questions 2. Mechanistic questions
How does the response loop work?
A specialized *sensor* monitors the variable. If the sensor is activated by the *stimulus*, it sends an *input signal* to the *integrating center*. The integrating center evaluates the information coming from the sensor and initiates an *output signal*. The output signal directs a *target* (or effector) to carry out a *response*. If successful, the response brings the regulated variable back into the desired range. If unsuccessful, there is an issue in the loop which can lead to death or a disease.
How does red blood cells transport oxygen? (Explain.) A. Teleological question B. Mechanistic question
A. Mechanistic question "Oxygen binds to hemoglobin molecules contained in the red blood cells. Hemoglobin is the oxygen-carrying pigment of the blood."
What is an example of a common feedforward control in dogs?
An easily understood physiological example of feedforward control is the salivation reflex. The sight, smell, or even the thought of food is enough to start our mouths watering in expectation of eating the food. This reflex extends even further, because the same stimuli can start the secretion of hydrochloric acid as the stomach anticipates food on the way.
What are emergent properties?
An emergent property is a property which a collection or complex system has, but which the individual members do not have.
How do organisms that survive in challenging habitats cope with external variability?
By keeping their internal environment relatively stable, an ability known as homeostasis
Molecules, cells, tissues, organs, organ systems, organisms, population A. Chemistry B. Molecular biology C. Cell biology D. Physiology E. Ecology
D. Physiology
(T/F): Reflexive control is very effective for causing changes in specific organs (e.g., increased blood flow to leg muscles while biking).
False; Local control
(T/F): A small change to the structure, or shape, of a molecule will not have a significant effect on the function.
False; it may have significant effects on the function.
(T/F): The concentration of glucose in the blood is relatively stable, because of a chemical equilibrium.
False; not because of a chemical equilibrium, but because there are homeostatic mechanisms in the body that work to constantly maintain the blood concentration within a limited range of values.
(T/F): Our cells are not spoiled and will only accept a wide range of surrounding conditions compared to an amoeba cell which can only tolerate a few different changes in its surroundings.
False; our cells *are spoiled* and will only accept *a certain range* of surrounding conditions compared to an amoeba what can *tolerate a lot* of different changes in their surroundings.
(T/F): Negative feedback loops are not homeostatic.
False; they are In fact, most reflexes feedback loops are homeostatic—that is, designed to keep the system at or near a setpoint so that the regulated variable is relatively stable.
______________________ is response that allows the body to anticipate change that is about to occur.
Feedforward control
Define: Local Control
In local control, a relatively isolated change occurs in a tissue. A nearby cell or group of cells senses the change in their immediate vicinity and responds, usually by releasing a chemical.
Define: Teleological approach
It involves searching for a reason or explanation for something as a function of its end, purpose, or goal. It is derived from two Greek words: telos (end, goal, purpose) and logos (reason, explanation).
(Excretion/Secretion): includes enzymes, hormones, or saliva.
Secretion
What is an example of physiology being an integrative science?
The body's response to dehydration is to retain water (by making urine that is more concentrated than normal) and to stimulate thirst, (leading to the absorption of water through the gastrointestinal tract.)
What is an example of how structure and function are closely related?
The change in one AA of the hemoglobin protein converts a normal hemoglobin cell to the form into a sickle cell.
What is the job of the integrating center?
The integrating center will take the input signal and compare it to the setpoint and then the difference between the input signal and the setpoint will lead to the integrating center to produce an output signal to fix the input signal which will form a response in the body.
Define: Mass Flow Rate
The mass of a substance which passes a given point per unit of time. *(mass/unit time)* A stream in the woods has a Na+ mass flow rate. A given mass of Na+ passes by a certain point along the stream per unit time. Mass flow rate has units of mass per unit time (e.g., mg/min).
What is the goal of homeostasis?
To maintain the ECF concentration relatively stable
(T/F): Complex systems possess emergent properties.
True
(T/F): Mass balance in an open system requires input equal to output.
True
(T/F): Negative feedback loops stabilize the regulated variable and thus aid the system in maintaining homeostasis. In the aquarium example, the heater warms the water (the response) and removes the stimulus (low water temperature).
True
(T/F): Physiology includes multiple levels, from molecular and cellular biology to the ecological physiology of populations.
True
(T/F): Physiology is an integrative science.
True
(T/F): Physiology is closely tied with anatomy at all levels of organization. (It is nearly impossible to study the physiology of the body without understanding the underlying anatomy.)
True
(T/F): Physiology is integrative in the sense that in order to understand many phenomena we need to understand how organ systems work together.
True
(T/F): There *must* be a factor that leads to the shut off of a positive feedback loop.
True
(T/F): These important regulated variables are kept within their acceptable (normal) range by physiological control mechanisms that kick in if the variable ever strays too far from its setpoint, or optimum value
True
(T/F): To maintain homeostasis, the human body monitors certain key functions, such as blood pressure and blood glucose concentration, that must stay within a particular operating range if the body is to remain healthy.
True
(T/F): One very common pathological condition in the United States is diabetes mellitus. Is this due to an internal failure or outside source? Explain.
True internal failure; it's a type of failure of homeostasis since the body does not maintain the regular levels of glucose but has too much.
Are the following example of compartmentation? (T/F): Extracellular space VS intracellular space. (T/F): Nucleus VS the rest of the cell (cytoplasm). (T/F): Cytoplasm contains different organelles which further divide the cell.
True for all
Who defined homeostasis as a state of maintaining "a similar condition"?
Walter Cannon
In 1929, an American physiologist named _______________ created the word homeostasis to describe the regulation of the body's internal environment. He explained that he selected the prefix "homeo" (meaning like or similar) rather than the prefix "homo" (meaning same). Why? He also pointed out that the suffix "-stasis" in this instance means what?
Walter Cannon Because the internal environment is maintained within a range of values (similar) *rather than* at an exact fixed value (same). A *condition*, not a state (that is static and unchanging).
One example of a positive feedback loop involves the hormonal control of uterine contractions during childbirth. Explain this process.
When the baby is ready to be delivered, it drops lower in the uterus and begins to put pressure on the cervix, the opening of the uterus. Sensory signals from the cervix to the brain cause release of the hormone oxytocin, which causes the uterus to contract and push the baby's head even harder against the cervix, further stretching it. The increased stretch causes more oxytocin release, which causes more contractions that push the baby harder against the cervix. This cycle continues until finally the baby is delivered, releasing the stretch on the cervix and stopping the positive feedback loop.
Define: Perfusion
blood flow and oxygen delivery to body tissues
The extracellular fluid serves as a ________ zone between an organism's external environment and ____________.
buffer; Intracellular fluid (ICF) inside cells {intra-, within}.
If we examine the composition of the ECF and ICF, we find that the concentrations of many substances are (different/identical) in the two compartments.
different
Note that homeostatic mechanisms are very (similar to/different from) a chemical equilibrium because chemical equilibrium (does/does not) require a constant influx of materials.
different from; does not
The body expends a considerable amount of E in order to maintain these ions (Na+, Cl−, and K+) in a state of _________________.
disequilibrium
CO2 produced during metabolism is (secreted/excreted) by the lungs.
excreted
Note: In order for a variable to be considered a regulated variable it must ?
have a sensor.
After a meal, blood glucose is (low/high), but then the body will intake the glucose into the cells to ____________ glucose levels. But when a diabetic person obtains a meal with high glucose their cells (will/will not) intake the glucose which can lead to _________. How can this be prevented?
high; regulate/maintain will not; death; if the diabetic is given synthetic insulin.
Furthermore, in a state of chemical equilibrium the chemical composition of the body compartments should be (different/identical).
identical
Life requires a nearly continuous (input/output) of energy. For most life on earth the ultimate source of this energy is __________.
input; the sun
The amount of oxygen that enters and *does not leave* the body equals the amount oxygen that?
is consumed by the body
At equilibrium, there (is/ is no) change in the ratio of the products to the reactants. The concentrations (are/ are not) stable.
is no; are
It (is/ is not) possible for a feedback system to perfectly control a regulated variable.
is not For this reason, there are *oscillations* in the value of a regulated variable *around the setpoint.*
Homeostasis (is/is not) different from equilibrium.
is; BECAUSE a common misconception is that homeostasis is somehow related to an equilibrium state...but it is NOT.
Thus, a Hohokam Indian living in Arizona who could conserve water by making concentrated urine (may/may not) have lived and had (less/more) offspring than another one who couldn't produce such concentrated urine. Making concentrated urine (has/does not have) adaptive significance for humans living in an arid environment.
may; more; has
(Na+) and (Cl−) are far (less/more) concentrated in the ECF than in the ICF, while (K+) is (less/more) concentrated in the ICF.
more; more
A pathway in which the response opposes or removes the signal is known as _________________.
negative feedback
Organisms are an (open/closed) system.
open
The human body is an (open/closed) system that exchanges heat and materials with the (inside/open) environment.
open; open
For example, when you drink a large volume of water, the dilution of your ECF triggers a mechanism that causes your kidneys to do what, and why?
remove excess water to protect your cells from swelling
The (response/feedback) loop starts with a____________ the change that occurs when the regulated variable moves out of its desirable range.
response; stimulus
For example, a drop-in blood glucose concentration that occurs as glucose is taken up by cells to be used for E, leads to the release of glucose from the liver. Thus, the concentration of glucose in the blood is in a (equilibrium/steady) state.
steady
Many foreign substances (called ___________) that enter the body, such as drugs or artificial food additives, are excreted by the liver and kidneys.
xenobiotics
