Chapter 1 Reading Questions
PHYSIOLOGY IS AN INTEGRATIVE SCIENCE
1. List the 10 human organ systems
 Circulatory
O Includes: heart, blood vessels, heart
O Function: transport of materials between all cells of the body
Digestive

O Includes: stomach, intestine, liver, pancreas
O Function: conversion of food into particles that can be transported into the
body; elimination of some wastes
 Endocrine
O Includes: thyroid gland, adrenal gland
O Function: coordination of body function through synthesis and release of
regulatory molecules
 Immune
O Includes: thymus, spleen, lymph nodes
O Function: defense against foreign invaders
 Integumentary
O Includes: skin
O Function: protection from external environment
 Musculoskeletal
O Includes: skeletal muscles, bones
O Function: support and movement
Nervous

O Includes: brain, spinal cord
O Function: coordination of body function through electrical signals and
release of regulatory molecules
 Reproductive
O Includes: ovaires and uterus, testes
O Function: perpetuation of the species
 Respiratory:
O Includes: lungs, airways
O Function: exchange of oxygen and carbon dioxide between the internal
and external environments
Urinary:

O Includes: kidneys, bladder
O Function: maintenance of water and solutes in the internal environment;
waste removal
4. Use possible answers to the question “Why do we breathe?” to explain the difference
between a teleological approach and a mechanistic approach.
 Teleological approach: because we need oxygen to survive
 Mechanistic: as we inhale, we obtain oxygen which is viable to our survival
6. Define homeostasis. (Fig. 1.4)
 Internal environment relatively stable
7.Explain what happens when homeostasis cannot be maintained.
 The normal function is disrupted and a disease state may result
 Diabetes. Type 1: beta cells of the pancreas are destroyed by the immune system, no insulin
is produce. Type 2: the pancreas produces insulin but target cells do not take up glucose.
Blood glucose remains high.
8. Explain the difference between extracellular fluid and intracellular fluid. How do they
relate to compartmentation? (Fig. 1.5)

Extracellular fluid is the watery internal environment that surrounds the cells. It
serves as the transition between an organism’s external environment. The
intracellular fluid is inside the cells.
9.
Define the law of mass balance. Express as an equation. (Fig. 1.6)

The law of mass balance says that if the amount of a substance in the body is to remain constant, any
gain must be offset by an equal loss.

Total amount of Substance X in the Body= Intake +Production-ExcretionMetabolism
10. How is mass balance maintained?

One option is excretion. A second output option for maintaining mass balance is
to convert the substance to a different substance through metabolism.
11. Express mass flow as an equation. What are scientists measuring when they calculate
mass flow of a substance?

Mass flow (amount X/min) = Concentration of X (amount X/vol) * Volume Flow
(vol/min)

Scientists use mass flow to follow material throughout the body
12. Define clearance. What organs are primarily responsible for clearance in the body?

Clearance: The rate at which the substance disappears from the blood.

Kidney and Liver
13. Explain the difference between equilibrium and steady state

Equilibrium implies that the composition of the body compartments is identical>
A steady state indicates that the compostion of both body compartments are
relatively stable. They are constantly moving back and forth between the 2
compartments. There is no net movement between the compartments.
14. If homeostasis does not mean equilibrium, then what does it mean?

Homeostasis means that the body is in a steady state. There are concetration
difference but they are relatively stable, keeping the body at homeostasis.
15. What is the goal of homeostasis?

The goal of homeostasis is to maintain the dynamic steady states of the body’s
compartments, not to make the compartments the same.
16. Diagram the four components of a simple control system.

Input signal  Integrating Center  Output Signal  Response
17. Define local control and give an example

Local control: homeostatic control that takes place strictly at the tissue or cell by
using paracrine or autocrine signals.

Ex. When oxygen concentration in a tissue decreases, the cells secrete a chemical
signal. The signal molecule diffuses to muscles in the blood vessel wall and sends
message for them to relax. This widens the blood vessel, which increases blood
flow to the tissue which brings more oxygen to the area
18. Define reflex control.

Any long distance pathway that uses the nervous system, endocrine system, or
both
19. Distinguish between a response loop and a feedback loop.

A response loop is a control pathway that begins with the stimulus and ends with
the response. Feedback loop: information about a homeostatic response that is
sent back to the integrating center
20. Diagram the seven steps of a reflex response loop.
21. Use the example of a house with both air conditioning and heating to explain how the two
climate-control systems exert antagonistic control over the temperature in the house

When the temperature in the house gets too high from the setpoint, the air
conditioning will kick in to cool it down to the setpoint. When the temperature in
the house gets too low from the setpoint, the heater will kick in to heat the house
to the setpoint. They two systems exert antagonistic control over the temperature
in the house because they work in opposition to each other.
22. What is the purpose of a feedback loop?

Regulates the response. Keeps it from exceeding the set point. Designed to keep
the system at or near a set point so that the regulated variable is relatively stable
23. Sketch a diagram of a negative feedback loop
24. Explain how the setpoint and sensitivity of a system play a role in maintaining
homeostasis

The set point is the point which the body is relatively stable. Sensitivity is the
range from the set point that is still acceptable.
25. Sketch a diagram of a positive feedback loop.
26. Explain how a positive feedback loop moves
a system away from homeostasis. How is a positive feedback loop shut off?

Positive feedback loop moves away from homeostasis because the response sends
the regulated variable even further from its normal value. A positive feedback
loop is shut off by some intervention or event outside the loop to stop the
response.
27. Define feedforward control and give an example

Anticipatory responses that start a response loop in anticipation of a change that is
about to occur

Ex. Salivation reflex
o Mouth starts to water in expectation of eating the food, same stimuli can
start the secretion of hydrochloric acid as the stomach anticipates food on
the way
28. Define and describe biological rhythms (or biorhythms). Give some examples. (Fig. 1.14)

Biological rhythms are regulated variables that change predictably and create
repeating patterns or circles of change. The timing of biological rhythms
coincinde with predictable environment change (light-dark circles, seasons)
29. Distinguish between acclimation and acclimatization

Acclimatization occurs naturally. Acclimation occurs artificially in a lab.
Acclimatization: the adaptation of physiological processes to a given set of
environment conditions
30. In an experiment, what is an independent variable? What is a dependent variable?

Independent variable: the one u change

Dependent variable: the response u are recording.
31. Why should every experiment have an experimental control?

To ensure that any observed changes are due to the manipulated variable and not
to changes in some other variable.