Transcript Introduction to MEDICAL PHYSIOLOGY

Introduction to
MEDICAL PHYSIOLOGY
BY
Dr. Arnold B. Fonollera, D.D.M.
Associate Professor
Biological Sciences Department
Medical Physiology defined
• The study of the various systems of the
body, from a molecular level through
integrated functioning as it relates to the
whole being.
• Generally, the term medical physiology
applies to human beings.
• What is understood about cellular
metabolism in any kind of plant or animal
can be extrapolated to human physiology.
• Therefore, the science of physiology
applies to all living things.
• Unlike branches of science focused on
form and structure, such as anatomy,
medical physiology is clearly concerned
with function.
DR. Walter Bradford Canon
1871-1945
• As a solo area of study, medical physiology stems from
the work of the early 20th century physiologist, Walter
Cannon, who presented his theory of homeostasis, or
body wisdom.
• Inspired by the earlier concept of milieu interieur,
Cannon proposed homeostasis as a state of internal
stability maintained by the body through deliberate
communication and regulation between body systems.
The Basis of Medical Physiology
• If one were to think of the human body
as a home heating system, it makes
perfect sense.
• When a heating thermostat, which has
been previously programmed, detects
that the ambient temperature has fallen
below an acceptable level, it sends an
electronic signal to the furnace to
produce more heat.
• The human body is equipped with
similar devices to trigger the
appropriate response to maintain
stability.
• However, the systems of the body are
not limited to electrical impulses and
use chemical messengers as well.
• The objective of this course is to help
students learn and comprehend
functions of the human body that are
essential for clinical medicine.
• Assist in acquiring a balanced
foundation in cellular and systemic
physiology in preparation for
advanced study in other basic
sciences and in clinical medicine.
• Emphasis is on understanding general
physiological principles and on how
cellular and organ system functions
are integrated within the organism.
• In this regard, physiology may be
distinguished from other basic
biomedical sciences because it deals
with the function of the whole
organism and emphasizes those
processes that regulate and control
entire organ systems.
Course
Objectives
• A systems approach will be used in concentrating on each of the
major organ systems individually.
• Examine the interrelationships and interdependencies that exist
among these various functional components.
• Illustrate the relevance of knowledge to the practice of medicine.
• A good working knowledge of physiology is a prerequisite for the
student and practitioner who must ultimately interpret and
evaluate disorders of function and provide rational treatment
plans.
Physiology is Different Than Histology or Anatomy
Concepts vs Memorization
like physics there are things to memorize
but it is the concepts that are essential
you must put in the intellectual effort to
understand the concepts
you must think about the ideas to become
comfortable with them
do not expect that you will learn
physiology by cramming for exams
Dynamic vs Static subject
new discoveries
new insights
so what you learn today may need to be
revised in the future
What is Physiology?
Focuses on homeostasis, the maintenance of important properties of living
organisms in a narrow range in the face of significant environmental fluctuations
Examples of properties
blood pressure
ionic composition of blood
osmolarity of blood
oxygen and carbon dioxide content of blood
acid-base balance of blood
glucose concentration of blood
body temperature
Goals are to identify the processes that control and regulate the important
properties of living systems
sensors – afferent pathways
integrating centers - set points
effectors – efferent pathways
SENSE
• How do these systems respond to perturbations
in order to return to normal?
• How does the body measure physiological
parameters?
molecular mechanisms
cellular mechanisms
RESPOND
Steady State vs Equilibrium:
The difference between Life and Death
equilibrium – no net change and no dissipation of energy
steady state – no net change but continuous dissipation of energy or
matter
Life is a steady state process. We continuously dissipate energy
to keep away from equilibrium.
steady state
rate of inflow
matches
rate of efflux
but flux through
the system
equilibrium
no net change
What is Physiology?
Focuses on homeostasis, the maintenance of important parameters in
living organisms in a narrow range (in the steady state) in the face of
significant environmental fluctuations
Example: body temperature
Sweat
Ducts
Core Body
Temperature
Sensors
elevated
Sweating
CNS
Integrating
Center
normal
range
Skeletal
Muscle,
Brown Fat
Shivering
decreased
Components of a Physiological System
EFFECTORS
elevated
INFORMATION INTEGRATION
Feedback control system
SENSORS
EFFECTORS
normal
range
decreased
Example: Factors Effecting a Physiological Parameter
INTEGRATING
CENTERS
SENSORS
stretch receptors
metabolic demands
DETERMINANTS
cardiac output
heart rate
stroke volume
contractility
vascular capacity
arterial vs venous
elasticity of vascular wall
blood volume
distribution arterial vs venous
FUNCTIONS
Blood Pressure
tissue perfusion
substrate delivery
waste removal
Physiology is the Basis of Medicine
many diseases cause organ dysfunction
medicine
tries to correct dysfunction
or minimize its effects
trying to restore system towards normal homeostatic setpoint
need to understand physiological parameters that can be manipulated
Example – Congestive Heart Failure (CHF)
leads to pump failure – inability to maintain adequate level of circulation
need to know causes of failure
some may be reversible others irreversible
if irreversible what else can be done to
maximize pumping
minimize symptoms
changes in blood volume, arterial or venous blood pressure
at molecular level need to know potential targets that can be modulated
Major Clinical Issues Related to the Course
1) What are the major determinants of blood
pressure?
2) Why do people develop hypertension
(HTN)?
3) How does knowledge of the physiology of
blood pressure regulation guide options
for the treatment of HTN?
4) What are the major determinants of
cardiac output and heart function?
5) How do people in heart failure
compensate for pump failure in order to
maintain output?
6) How does a knowledge of cardiac
physiology guide options for treatment of
heart failure?
7) How does the kidney regulate composition
and volume of body fluids?
8) How is acid-base balance maintained?
9) How does the respiratory system conduct
and regulate gas exchange?
STUDY WELL!