INTRODUCTION TO
PHYSIOLOGY
BY DR QAZI IMTIAZ RASOOL
OBJECTIVES 24
1.
Define physiology and homeostasis as a method of study of
physiology.
2.
Overview the intracellular and extracellular compartments and
contrast the difference in their fluid composition.
3.
Explain the concept of extracellular fluid as internal environment
and relate this to the concept of steady state balance.
4.
Identify the control systems of the body (nervous and chemical)
and describe briefly their general roles.
5.
Identify the components of control system.
What is LIFE?
LIFE
“Things”organized to use energy and raw materials
from their environment, maintain their integrity and
reproduce
A physician and medical researcher who understands
physiology
a) -both its potential contributions and limitations
b) -is better equipped to make intelligent and
perceptive decisions about the body.
MEANING OF WORD PHYSIOLOGY?
GREEK;-
- PHYSIS
= "nature, origin";
-LOGIA,
="study of“ . ology- branch of learning
Physiology:biological sciences -deals with the study of body
functions, which r
-Biochemical
-Physical
-Mechanical
How can study of physiology help you?
1. Understanding the “normal” function gives incite into potential problems
that can occur
2. Gives an idea of the potential cause or extent of problems resulting from
disease - pathophysiology
3. Understanding the normal helps to search for potential treatments
4. Help understand how substances impact the body – drugs
1.
2.
3.
4.
- divided into the following specialties:
Cell physiology – study of cell
Special physiology - study of specific organ
Systemic physiology – study of system
Pathological physiology – study of the effect of disease on cell, tissue,
organ and system.
Human Physiology
Is base for different branches
e.g.Genomics,Pathophysiology,Pharmacolog,Immunology,Biochemistry,
Microbiology,Medicine
Physiology is the Basis of Medicine
It-
a)
-tries to correct dysfunction
b)
-or minimize its effects
c)
- trying to restore system towards normal homeostatic
setpoint
-need to understand physiological
Parameters that can be manipulated
d)
The Nobel Prize in Physiology or Medicine has been awarded 100 times to 195
.
Nobel Laureates between 1901 and 2009
Major Branches of Physiology
1.
Comparative Physiology
2.
Environmental Physiology
3.
Evolutionary Physiology
4.
Developmental Physiology /Stem- cell
5.
Molecular Cell Physiology
6.
Physiological cloning
Levels of Organization
Basic cell functions include:
1.
Self-organization: Using resources from the environment to create
the cell
2.
Self-regulation: Maintain self-integrity in the face of disturbances
3.
Self-support and movement: Having structrures that give specific
form to the cell and to move materials within the cell or to move the cell
itself
4.
Self-replication: Reproducing to carry on the species, and to repair
damage
Different Level of Physiological Research
Organization of the human body
Macromolecule
Organelle
ATOM
Cells
Tissues
Molecule
Organisms
Organ
Organs systems (Human body)
The integration between systems of the body
BODY AS AN OPEN SYTEM
What is Homeostasis?
1. The body’s attempt to maintain
“normal” levels within your
body
2. Homeostasis is often referred
to as a dynamic equilibriumwhich is a mechanism to
ensure that all body systems
function within an acceptable
range to sustain life.
Body Fluid Compartments
1. If you manipulate one body fluid
compartment, it has an effect on
another compartment.
2. Body fluid compartments have
different sizes and volumes, and
different compositions.
3. Although the volume and substances
dissolved in the fluid of one
compartment is different than another
compartment, each compartment
has the same number of particles
dissolved in the water.
FLUID COMPARTMENTS
EXTRA CELLUAR FLUID
INTRA CELLULAR FLUID
(cytosol
PLASMA
1.
2.
3.
4.
5.
6.
CSF
Intra ocular
Pleural
Peritoneal
Synovial
Digestive Secretions
INTERSTITIAL
FLUID
TRANSCELLULAR
FLUID
Water
1. Water makes up 60% of our body weigh 42 lt.
2. Divide this into two compartments
1. 40% Intracellular water 28 l
2.
20% Extracellular water 14 l
Body Fluid Compartments
1.
The total amount of water in your body is divided into two
compartments
1. Intracellular water is inside of your cells. Most of your water is
here.
2. Extracellular water is outside of your cells. There are three
types.
1. Interstitial fluid (the water immediately outside cells, between
and around cells) (16%)
2. Plasma fluid (the water inside blood vessels, but not in blood
cells)
(4-5%)
3. Transcellular fluid (the water enclosed in chambers lined by
epithelial membranes, including the GI tract and synovial
joints) (1-3%)
Different compositions across the membrane: How
can this be?
PERCENTAGE OF H2O IN TISSUES
Disorders of H2O Balance: Dehydration
1 Excessive loss of H2O from
ECF
(a) Mechanism of dehydration
2
ECF osmotic
pressure rises
Cells lose H2O
3 to ECF by
osmosis; cells
shrink
“Homeostasis”
GREEK ‘’ HOMOI= SAME”
STASIS= ‘’ STANDING STILL”
Definition
the maintenance of a relatively constant steady stable state of
internal environment
Two general points within homeostasis
1.
Autoregulation or Intrinsic regulation – results when cell, organ or system
adjusts its activity automatically.
2.
Extrinsic regulation - results from activity of nervous system or endocrine
system
PROPERTIES OF HOMOSTASIS
1. Central concept of physiology
2.
Maintenance of the relative stable “internal
environment” in an ever changing world.
3.
Balance or equilibrium of all functions.
4.
It is a dynamic steady state.
5.
Dynamic: parameters do change
6.Steady state: parameters change in very narrow limits.
7.It has to respond to both internal and external threats to that
stability
8.Disease, by and large, is a failure of homeostasis
9.Excessive perturbations result ultimately in death of the
organism
Extracellular fluids
Intracellular
fluid
Plasma
Interstitial fluid/tissue fluid
Fluid of special compartments:
pericardial fluid, pleural fluid, cerebrospinal fluid ,plasma ,lymph
Internal environment
Intracellular
fluid
Plasma
Interstitial fluid
Extracellular fluid directly baths body cells
Internal environment = Extracellular fluid
Balancing the Internal and External Environment
1.Cells, the fundamental units of life, exchange nutrients
and wastes with their surroundings:
2.The intracellular fluid is “conditioned by”…
3. the interstitial fluid, which is “conditioned by”
4. the plasma, which is “conditioned by” …
5. the organ systems it passes through.
ICF
ISF
plasma
internal environment
organs
external
environment
Control Systems
In order to maintain homeostasis, control system must
be able to
1.
Detect deviations from normal in the internal
environment that need to be held within narrow
limits
2.
Integrate this information with other relevant
information
3.
Make appropriate adjustments in order to
restore factor to its desired value
Feedback Loops
1.Sensor:
Detects deviation from set point.
2.Integrating center:
Determines the response
ACCORDING TO THE SET-PIONT
3.Effector:
Produces the response.
Homeostatic Control Mechanisms
3 Input:
Information
sent along
afferent
pathway to
Control
center
4 Output:
Information sent
along efferent
pathway to
Effector
Receptor (sensor)
2 Change
detected
by receptor
5
1
Stimulus:
Produces
change
in variable
Variable (in homeostasis)
Response of
effector feeds
back to influence
magnitude of
stimulus and
returns
variable to
homeostasis
Control Systems
Reference
Signal
Error
Signal
Comparator
Controller
Feedback
Signal
Sensor
Effectors
Regulated
Variable
Law of Mass Balance
Most simply, ins = outs
Homeostasis is not the
same as equilibrium
E.g., membrane
potentials
Regulation of the Body Functions
3 regulatory systems have to coordinated and acts as one
system, “feedback control system”.
1. Endocrine/ Chemical Regulation- process performed by
hormone or active chemical substance in blood or tissue.
-It response slowly, acts extensively and lasts for a long time.
2. Nervous Regulation- a process in which body functions are
controlled by nerve system
- Pathway: nerve reflex
- Types: unconditioned reflex and conditioned reflex
- Example: baroreceptor reflex of arterial blood pressure
- Characteristics: response fast; acts exactly or locally, last for a
short time
3. Autoregulation – a tissue or an organ can directly respond to
environmental changes that are independent of nervous and
hormonal control
Characteristics：
Amplitude of the regulation is smaller than other two types.
Extension of the effects is smaller than other two types.
REGULATION OF HOMEOSTASIS
The 2 work together or independently to regulate
homeostasis


1. NERVOUS SYSTEM. Active muscle contraction – produces 
CO2 and  O2 in blood. Nerve cells detects changes in blood
gases  sends impulses to brain  brain send impulses to heart
to  heart rate  brain also sends impulses to respiratory centre
in brain to  breathing rate  blood gases are quickly restored
back to normal.
2. ENDOCRINAL SYSTEM
 E.g. Active muscle contraction  produces  CO2 and  O2 in
blood   CO2 causes the release of epinephrine into blood 
epinephrine causes  in heart rate  delivery to and removal of CO2
in lungs .
Nervous
Endocrine
Wired
Wireless
Neurotransmitters
Hormones
Short Distance
Long Distance
Closeness
Receptor Specificity
Rapid Onset
Delayed Onset
Short Duration
Prolonged Duration
Rapid Response
Regulation
Homeostasis & Controls
 Successful compensation
 Homeostasis reestablished
 Failure to compensate
•Pathophysiology
•Illness
•Death