, Chapter 1
Introduction to Physiology
1.1 Physiology is an integrative science
Physiology is the study of the normal functioning of a living organism and its component parts, including all its
chemical and physical processes.
Emergent properties: properties that cannot be predicted to exist based only on knowledge of the system’s
individual components.
Proteomics: the study of proteins in living organisms.
cell membrane/ plasma membrane:A lipid and protein barrier that separates cells from their external
environment.
Integration
The integration of function across many levels of organization
is a special focus of physiology
Cells: the smallest unit of structure capable of carrying out all
life processes.
Tissues: Collections of cells that carry out related functions
Organs: Tissues form structural and functional units
Organ systems: groups of organs integrate their functions
Immune system (lympathic system): protects the internal
environment from foreign substances by intercepting material
that enters through the intestines and lungs or through a break
in the skin.. Immune tissues are closely associated with the
circulatory system.
1.2 functions and mechanisms
Function: the “why” of the system or event:
Mechanism: the ‘how’ of a system or event
Mechanistic approach: examines process.
.
Thinking about a physiological event in terms of its adaptive significance is the teleological approach to science
.
Translational research uses the insights and results gained from basic bio- medical research on mechanisms to
develop treatments and strategies for preventing human diseases.
1.3 Themes in physiology
Physiology can be divided into five themes:
1. structure and function across all levels of organization
- Molecular Interactions: The ability of individual molecules to bind to or react with other molecules is
essential for biological function. A molecule’s function depends on its structure and shape, and even a small
change to the structure or shape may have significant effects on the function.
- Compartmentation is the division of space into separate compartments. Compartments allow a cell, a
tissue, or an organ to specialize and isolate functions.
2. energy transfer, storage, and use
3. information flow, storage, and use within single organisms and within a species of organism
4. homeostasis and the control systems that maintain it
5. evolution
, Chapter 1
Introduction to Physiology
1.4 homeostasis
The body monitors its internal state and takes action to correct disruptions that threaten its normal function.
If the body fails to maintain homeostasis, a pathological condition may result
Diseases fall into two groups
- the problem arises from internal failure of some normal physiological process
- the problem originates from some outside source.
Pathophysiology: The study of body functions in a disease state
What Is the Body’s Internal Environment?
For multicellular animals, the body’s internal environment, is the watery internal environment that surrounds the
cells, called the extracellular fluid (ECF). Extracellular fluid serves as the transition between an organism’s
external environment and the intracellular fluid (ICF) inside cells. It’s the buffer
Homeostasis Depends on Mass Balance
The law of mass balance: if the amount of a substance in the body is to remain constant, any gain must be
offset by an equal loss The amount of a substance in the body is also called the body’s load.
Total @ Mount of = intake + Production -
Substance ✗ inthebody excretion -
metabolisme
To maintain mass balance, the body has two options for output:
- Excretion: elimination of material from the body, usually through the urine, feces, lungs, or skin.
- Convert the substance to a different substance through metabolism.
Scientists use mass flow to follow material throughout the body.
Mass flow: the rate of transport of a substance x as it moves through body fluids or into and out of the body.
Mass flow = Concentration of ✗ ✗ volume flow
Excretion Clears Substances from the Body
Clearance: the rate at which the substance disappears from the blood. Clearance is usually expressed as a
volume of blood cleared of substance x per unit of time
Homeostasis Does Not Mean Equilibrium
Steady state is not the same as equilibrium
Because of these concentration differences in the ECF and the
ICF, the two fluid. compartments are not at equilibrium. Instead
the ECF and ICF exist in a state of relatively stable disequilibrium
, Chapter 1
Introduction to Physiology
1.5 Control Systems and Homeostasis
All control systems have three components:
(1) an input signal
(2) a controller, or integrating center that integrates incoming information and initiates an appropriate response
(3) an output signal that creates a response.
Local Control Is Restricted to a Tissue
The simplest form of control is local control, which is re- stricted to the tissue or cell involved
Reflex Control Uses Long-Distance Signaling
Response loop: Stimulus -> sensor -> input signal -> integrating center -> output signal -> target -> response
Feedback loop: response “feeds back” to influence the input portion of the pathway
- negative feedback loop: A pathway in which the response opposes or removes the signal
- positive feedback loop: the response reinforces the stimulus rather than decreasing or removing it.
(the response sends the regulated variable even farther from its normal value)
Feedforward control: A few reflexes have evolved that enable the body to predict that a change is about to
occur 1 and start the response loop in anticipation of the change.
Biological Rhythms Result from Changes in a Setpoint
circadian rhythm: some form of daily biological rhythm
acclimatization: The adaptation of physiological processes to a given set of environmental conditions
acclimation: the process takes place artificially in a laboratory setting
Introduction to Physiology
1.1 Physiology is an integrative science
Physiology is the study of the normal functioning of a living organism and its component parts, including all its
chemical and physical processes.
Emergent properties: properties that cannot be predicted to exist based only on knowledge of the system’s
individual components.
Proteomics: the study of proteins in living organisms.
cell membrane/ plasma membrane:A lipid and protein barrier that separates cells from their external
environment.
Integration
The integration of function across many levels of organization
is a special focus of physiology
Cells: the smallest unit of structure capable of carrying out all
life processes.
Tissues: Collections of cells that carry out related functions
Organs: Tissues form structural and functional units
Organ systems: groups of organs integrate their functions
Immune system (lympathic system): protects the internal
environment from foreign substances by intercepting material
that enters through the intestines and lungs or through a break
in the skin.. Immune tissues are closely associated with the
circulatory system.
1.2 functions and mechanisms
Function: the “why” of the system or event:
Mechanism: the ‘how’ of a system or event
Mechanistic approach: examines process.
.
Thinking about a physiological event in terms of its adaptive significance is the teleological approach to science
.
Translational research uses the insights and results gained from basic bio- medical research on mechanisms to
develop treatments and strategies for preventing human diseases.
1.3 Themes in physiology
Physiology can be divided into five themes:
1. structure and function across all levels of organization
- Molecular Interactions: The ability of individual molecules to bind to or react with other molecules is
essential for biological function. A molecule’s function depends on its structure and shape, and even a small
change to the structure or shape may have significant effects on the function.
- Compartmentation is the division of space into separate compartments. Compartments allow a cell, a
tissue, or an organ to specialize and isolate functions.
2. energy transfer, storage, and use
3. information flow, storage, and use within single organisms and within a species of organism
4. homeostasis and the control systems that maintain it
5. evolution
, Chapter 1
Introduction to Physiology
1.4 homeostasis
The body monitors its internal state and takes action to correct disruptions that threaten its normal function.
If the body fails to maintain homeostasis, a pathological condition may result
Diseases fall into two groups
- the problem arises from internal failure of some normal physiological process
- the problem originates from some outside source.
Pathophysiology: The study of body functions in a disease state
What Is the Body’s Internal Environment?
For multicellular animals, the body’s internal environment, is the watery internal environment that surrounds the
cells, called the extracellular fluid (ECF). Extracellular fluid serves as the transition between an organism’s
external environment and the intracellular fluid (ICF) inside cells. It’s the buffer
Homeostasis Depends on Mass Balance
The law of mass balance: if the amount of a substance in the body is to remain constant, any gain must be
offset by an equal loss The amount of a substance in the body is also called the body’s load.
Total @ Mount of = intake + Production -
Substance ✗ inthebody excretion -
metabolisme
To maintain mass balance, the body has two options for output:
- Excretion: elimination of material from the body, usually through the urine, feces, lungs, or skin.
- Convert the substance to a different substance through metabolism.
Scientists use mass flow to follow material throughout the body.
Mass flow: the rate of transport of a substance x as it moves through body fluids or into and out of the body.
Mass flow = Concentration of ✗ ✗ volume flow
Excretion Clears Substances from the Body
Clearance: the rate at which the substance disappears from the blood. Clearance is usually expressed as a
volume of blood cleared of substance x per unit of time
Homeostasis Does Not Mean Equilibrium
Steady state is not the same as equilibrium
Because of these concentration differences in the ECF and the
ICF, the two fluid. compartments are not at equilibrium. Instead
the ECF and ICF exist in a state of relatively stable disequilibrium
, Chapter 1
Introduction to Physiology
1.5 Control Systems and Homeostasis
All control systems have three components:
(1) an input signal
(2) a controller, or integrating center that integrates incoming information and initiates an appropriate response
(3) an output signal that creates a response.
Local Control Is Restricted to a Tissue
The simplest form of control is local control, which is re- stricted to the tissue or cell involved
Reflex Control Uses Long-Distance Signaling
Response loop: Stimulus -> sensor -> input signal -> integrating center -> output signal -> target -> response
Feedback loop: response “feeds back” to influence the input portion of the pathway
- negative feedback loop: A pathway in which the response opposes or removes the signal
- positive feedback loop: the response reinforces the stimulus rather than decreasing or removing it.
(the response sends the regulated variable even farther from its normal value)
Feedforward control: A few reflexes have evolved that enable the body to predict that a change is about to
occur 1 and start the response loop in anticipation of the change.
Biological Rhythms Result from Changes in a Setpoint
circadian rhythm: some form of daily biological rhythm
acclimatization: The adaptation of physiological processes to a given set of environmental conditions
acclimation: the process takes place artificially in a laboratory setting
