Unit 1: Intro to Physiology, Homeostasis and Molecules

Question 1

Definition of Physiology

Answer 1

the study of the normal functions of
living organisms and their parts (cells, tissues,
organs, organ systems)

This includes all of the
chemical and physical processes involved in cell, tissue, organ and organismal function that are necessary to maintain life.

Question 2

Describe the different levels of organization for living organisms.

Answer 2

chemical
cellular
tissue
organ
organ system
organism
pop. of 1 species
ecosystem of diff species
biosphere

Question 3

Chemical Level

Answer 3

Ø Atoms and molecules important for life. E.g. hydrogen and oxygen atoms combine to form water molecules

Question 4

Cellular Level

Answer 4

Molecules combine to form organelles, which form cells
Cells are the basic structural and functional units of the human body (and of all living things)

Question 5

Tissue Level

Answer 5

a group of structurally similar cells performing a common function.
4 types

Question 6

list the 4 major tissue types

Answer 6

i. Epithelial tissue
ii. Connective tissue
iii. Muscle Tissue
iv. Nervous Tissue

Question 7

Organ Level

Answer 7

Ø Two or more tissues working together to perform a common function
Ø E.g. the stomach contains all 4 major tissue types working together to perform the function of digestion.

Question 8

Organ System Level

Answer 8

Several related organs working together for a common purpose

E.g. Urinary System: Kidneys, ureters, bladder and urethra work together to perform waste elimination.

10 systems

Question 9

Organism Level

Answer 9

All organ systems function together to maintain life.

Question 10

List the 10 different organ system:

Answer 10

a. Circulatory (cardiovascular)
b. Digestive (gastrointestinal)
c. Endocrine
d. Immune (includes lymphatic system)
e. Integumentary (skin)
f. Musculoskeletal
g. Nervous
h. Reproductive
i. Respiratory (pulmonary)
j. Urinary (renal)

Question 11

Circulatory (cardiovascular)

Answer 11

– distributes materials by
pumping though blood vessels

Question 12

Digestive (gastrointestinal)

Answer 12

• takes up nutrients (including
  water) and removes wastes

Question 13

Endocrine

Answer 13

coordinates body functions

Question 14

Integumentary (skin)

Answer 14

protection from external environment

Question 15

Musculoskeletal

Answer 15

support and body movement

Question 16

Nervous

Answer 16

– coordination of body function

Question 17

Reproductive

Answer 17

produces gametes (eggs and sperm)

Question 18

i. Respiratory (pulmonary)

Answer 18

exchanges gases (O2 and CO2

Question 19

Urinary (renal)

Answer 19

controls water and electrolyte balance;
removes wastes

Question 20

Contrast the differences between teleological and mechanistic approaches in physiology.

Answer 20

Teleological approach – considers the adaptive significance of a physiological event and answers questions
like “why does this happen”.
Ø E.g.1: Why do humans shiver? Answer: to elevate a low body temperature.
Ø E.g.2: Why do red blood cells transport oxygen? Answer: Cells need oxygen to make ATP.

2. Mechanistic approach – answers questions about how a particular physiological event takes place and looks at the cause and effect sequences of physical and chemical processes that lead to its occurrence (i.e. what is the mechanism of action).

Question 21

List and explain the four key themes in physiology

Answer 21

Structure and function are closely related
Ø Most physiological functions can be traced back to molecular interactions within and between cells. Cellular processes then affect
how tissues and organs function.
Ø Compartmentalization: Tissues (epithelial tissues) separate the external environment from the internal environment of the body; cell
membranes separate cells from surrounding fluids; the body can be divided

Living organisms need energy
Ø Most of the molecular and chemical processes in the body that
regulate everything from growth and reproduction, to skeletal
muscle movements to the movement of molecules across cell
membranes are powered by the energy molecule ATP (adenosine
triphosphate; and to a lesser extent by GTP, guanosine
triphosphate).

Information flow coordinates body functions
Ø Cell to cell communication – chemical (paracrines, hormones,
neurohormones) or electrical (neurotransmitters) signals
Ø Occurs locally (between neighboring cells) and over long distances
(e.g. from the brain to another organ).

Homeostasis
Control systems regulate the internal environment to stay within a
narrow range of conditions.

Question 22

Define and describe homeostasis

Question 23

Extracellular fluids (ECF) –

Answer 23

fluid outside ofcells

i. Interstitial Fluid (ISF) – fluid surrounding cells
in tissues
ii. Intravascular Fluid (IVF) – fluid contained in
blood vessels (plasma) or lymphatic vessels
(lymph)

Question 24

Intracellular fluid (ICF)

Answer 24

fluid inside of cells

Question 25

emergent properties

Answer 25

result from the non-linear interaction between all of the parts (in the case of
physiology: cells, organs, organ systems).

i. A property that the whole organ/system has, that the individual parts do
not. i.e. the whole is greater than the sum of its parts.

• property that can’t be predicted based on the knowledge of the individual components of a system

Question 26

proteomics

Answer 26

study of proteins in living organisms

Question 27

Homeostasis

Answer 27

the ability of the body to maintain a relatively
constant internal environment (stability of ECF) despite changes in the external environment

Question 28

describe homeostasis

Answer 28

cells of the body can only survive in a narrow range of conditions (physiological limits). The body’s organs and organ systems function together to maintain this narrow range and therefore keep cells alive

Ø Disease is a failure to maintain homeostasis. Medical interventions can help to restore homeostasis and may help to prevent damage to organs/tissues.

• depends of mass balance

-

Question 29

list the variables in the body that are regulated

Answer 29

1. Temperature
2. pH
3. Blood gases (O2 and CO2)
4. Salinity (concentrations of ions and other solutes)
5. Nutrients

Question 30

What does Homeostasis not mean?

Answer 30

1. Equilibrium between the ECF and ICF(this would mean the composition is identical) (the composition of each is quite different, and can vary within physiological limits)
2. “Never changing”

Question 31

What does homeostasis mean?

Answer 31

1. A dynamic steady state between the ICF and ECF.
2. That internal conditions/parameters can change (and do so often) in response to environmental challenges.
3. That regulated variables have a range of values, not a single value (e.g. normal body temperature has a range of 35.5 – 37.7○C). The normal range for the value is the setpoint within
   which the body’s systems will not initiate compensation.

Question 32

what does it mean that there is a dynamic steady state between the ICF and ECF?

Answer 32

materials are moving back and fourth between the ICF and ECF but there’s no net movement and under normal conditions, the composition of each compartment, while different from one another (disequilibrium), is relatively stable.

Question 33

Law of mass balance (definition, what is maintained thru it)

Answer 33

if the amount of substance in the body is to remain constant any gain has to be offset by equal loss
- load, gain loss
- O2 CO2 salts and H+ are maintained thru this

Question 34

What does it mean to “keep the internal environment stable”

Answer 34

balance water loss with appropriate water intake

Question 35

load

Answer 35

the amount of substance (e.g. water, Na+.
Ca++, glucose, etc).
- Remains constant if gains of the substance are offset by losses of the substance.

Question 36

What is the equation of law of mass balance

Answer 36

Total amount of substance in the body (X)= intake + production - excretion - metabolism

Question 37

Gains

Answer 37

adds to load from two sources:
i. Enters the body from the outside (e.g. ingestion)
ii. Produced metabolically by the body.

Question 38

Loss

Answer 38

subtracts from load from two sources:

i. Excretion (urine, feces, sweat, etc.)
ii. Metabolically removed from the body (convert a substance to something else)
Ø e.g. glucose is metabolized to CO2 and water – a loss of glucose, but a metabolic gain of CO2 and water).

Question 39

excretion

Answer 39

elimination of material from the body thru urine feces lung or skin

Question 40

mass flow

Answer 40

the rate of transport of a substance (x) as it moves thru the body fluids or into/out of the body

Question 41

what is the equation of mass flow

Answer 41

mass flow= concentration of x X volume flow

amount x/ min= amount/ vol X vol/min

Question 42

describe what mass flow is

Answer 42

applies not only to the entry, production, and removal of substances but also to the movement of substances from one compartment in the body to another. When materials enter the body, they first become part of the extracellular fluid.

Question 43

clearance

Answer 43

rate at which substance disappears from the blood
- indirect measure
- volume of blood cleared of substance (x)/ time

Question 44

where does clearance take place in the body?

Answer 44

saliva sweat breast milk

Question 45

How do control systems help maintain homeostasis?

Answer 45

1. Monitoring/detecting changes to regulated variables (e.g. temperature, pH, blood pressure, etc.) that result in a loss of homeostasis.
   Ø Regulated variables in the body’s internal environment have a particular setpoint range (optimum values that will not activate compensation).
2. Initiating mechanisms that adjust regulated variables to compensate for the change.

Question 46

List the 3 components of control systems

Answer 46

1. input signal (initiated by a sensor/ receptor)
2. Integrating centre(integrates incoming input signals and initiates the appropriate response)
3. Output signal – creates the appropriate response

Question 47

local control

Answer 47

within a cell or tissue
eg; a change occurs in a tissue a nearby cell/cells sense the change in their area and respond by releasing a chemical, response happens only in the region where the change took place

Question 48

Long distance (reflex) control

Answer 48

involves signaling to distant cells using the nervous system or endocrine system (the body’s major control systems)
- can be broken down into a response loop and feedback loop

Question 49

Describe and diagram the seven steps of a reflex pathway

Answer 49

1. Stimulus – change in the regulated variable to a value outside of the setpoint range.
2. Sensor/Receptor – detects changes in a regulated variable
3. Input Signal – relays info about the change from sensor/receptor
4. Integrating center – integrates input signals; determines and initiates appropriate output signal for response. In nervous system – brain/spinal cord; in endocrine system = endocrine gland).
5. Output signal – signal sent from integrating center to adjust activity of the effector/target (neural signal/neurotransmitter or a hormone).
6. Effector/target – cells/organs/tissues whose activity will be modified to produce the appropriate response. Typically muscles or glands.
7. Response – causes a change/adjustment of the regulated variable

Question 50

Negative feedback loop

Answer 50

most common in the body)
a. are homeostatic – stabilize the variable (i.e. the response created by the effector returns the variable to within the optimal value range which shuts off the response loop).

b. Restores homeostasis but cannot prevent the initial change

Question 51

Positive feedback loops

Answer 51

a. usually described as non-homeostatic (although there are several examples that occur in the body, without which homeostasis might not be maintained).
b. Amplify (or reinforce) the stimulus, causing the regulated variable to get further away from the normal value.
c. Requires an outside signal to be shut off.

Question 52

Feedforward Control (Anticipatory Responses)

Answer 52

1. A change in a regulated variable is anticipated based on a small
   stimulus.
2. The anticipation allows the body to prevent a loss of homeostasis.

a. Sight, smell or thought of food triggers salivation and hydrochloric acid release by the stomach (anticipation of food entering the mouth/stomach).
b. Increased respiratory rate at the the start of exercise, before a change in blood gasses has occurred (anticipating that more O2 will be needed and more CO2 will need to be eliminated).
c. Can also be learned or behavioural (when it is -40C in Winnipeg, we put on several layers of clothes and a warm jacket, anticipating and preventing our body temperature from getting too low).

Question 53

Hypothesis

Answer 53

logical proposed explanation for an event based
on limited data/observations.

Question 54

Independent variable

Answer 54

is the cause, in “cause and effect”. It can be manipulated by the researcher, but its value is not dependent on other variables in the study. – in our example, the different sweeteners.

• on horizontal x axis

Question 55

Dependent variable

Answer 55

is the effect in “cause and effect”. Its value is dependent on the independent variable. – in our example, blood glucose levels.

• on the vertical y axis

Question 56

Experimental Control

Answer 56

duplicate of experimental group, but the independent variable does not change. – in our example – a control group would be the same group of individuals having coffee with no artificial sweetener.

Question 57

Data Collection and Analysis

Answer 57

Collect data points – in our example, test blood glucose levels after drinking a cup of coffee with each sweetener. Graph and statistically analyze data.

Question 58

Replication

Answer 58

Repeat the experiment – in our example do the trials again with the same group of people and with others.