General rules & guidelines
• Punctuality in all classes
• 100% attendance
• No absenteeism in assessments university rule strictly
applied
• Submission of practical reports within 1 week-delay will
invite penalty by the day
• Interaction with lecturer and other students
(within time constraints)
• How to study
i. Notes in class
ii. Lecturer’s notes
iii. Standard text books
• 1. Be regular in attending classes. Your lecturer has taken a
lot of pains to prepare the subject. You must draw maximum
benefit from this.
• 2. If you have doubts, have them clarified
• 4. Take down points during the lecture/tutorial which you
feel are important, and also those which you don’t seem to
understand. Compare your notes with the information in the
book, and make whatever additions you feel are important.
Inn this manner you can compile your own information on a
given topic and use it for the exams.
• 5. You are now studying a clinically oriented syllabus. So
don’t be alarmed by clinical terms being htrown at you.
• 6. Read standard prescribed text books regularly
Introduction to Human Physiology
• Course Co-ordinator
•
•
•
Dr Sami Al Rawas MD PhD
Consultant, Clinical Physiology
(Neurophysiology)
• Introduction:
• Text Book
• i. Principles of Anatomy & Physiology. Tortora
& Grabowsky. Wiley &
Sons; 2003
• Reference books
• i. . Text Book of Medical Physiology . Guyton &
Hall. 12th edn. Saunders, London. 2011
• Ii. Ross ands Wilson. Anatomy and Physiology in
Health and Disease. 10th Edn. Churchill
Livingstone. 2006
•
•
Homeostasis
•
•
&
Control Mechanisms - I
•
•
•
•
Objectives
1. Explain the meaning of the term internal environment and homeostasis (Giving
examples) and appreciate the importance of constancy of the milieu interior.
2. State that homeostasis involves maintaining the internal environment at a
constant level or between narrow limits.
3. Explain that homeostasis involves monitoring levels of variables and correcting
changes which may occur under various situations –Physiological or Pathological
•
4. Understand what is meant by controlled variable and set point.
•
5. Explain the feed back mechanisms in control system i.e negative feedback
mechanisms.
•
6. List examples of negative feed back systems, and describe 2 such
•
7. Give an example of positive feedback mechanisms e.g. parturition (child birth).
•
8. Understand that disease alters homeostasis of the internal
environment and may cause death
• Definition of Physiology
“Is the science of how the body systems work, and
the ways in which their integrated cooperation
maintains life and health of an individual”
• Pathology is the study ofabnormsalities in body
tissues and how they affect body functions and
cause illness
• Pathophysiology is how the body function resposnds
to Pathology
Atoms
Molecules
Organelles
Cells
Tissues
Organs
Systems
Organism
• Integumentary (Skin) Physiology
(system)
• Cardiovascular Physiology (system)
• Respiratory Physiology (system)
• Gastrointestinal Physiology (system)
• Renal Physiology (system)
• Reproductive Physiology (system)
• Musculo-skeletal Physiology (system)
• Neurophysiology Nervous system
• Endocrine Physiology (system)
“La fixité du milieu
intérieur est la condition
de la vie libre.”
“The fixity of the internal
environment is the
condition for free life.”
What is the INTERNAL ENVIRONMENT?
•
•
•
•
•
•
•
ECF
1. Na+ mMol/L
2. K+
3. HCO34 Cl
5. Anions (proteins)
6. Glucose (mg%)
145
ICF
15
5
150
28
10
105
5
100
5
40
10
• Egs of ECF: plasma; CSF; lymph; aqueous humor
•
Examples of constancy of the Internal Environment
1.
Body core temperature: 370C
2.
Arterial Blood: PaO2 100 mmHg; PaCO2 40 mmHg;
pH 7.4
3.
Blood sugar (glucose) :
4.
Blood pressure: 120/80 mmHg
5.
Electrolytes: Na+ 140 mmol/L; K+ 4 mmol/L
pH : stomach= 2-4 , small intestinal pH about 8
urine about 6
100 mg% (5 mmols)
All body cells and systems contribute towards this
•
•
Homeostasis
&
Control Mechanisms -II
• Definition :
• Claude Bernard’s “Milieu Interieur” or the
Internal Environment:
• Maintenance of the constancy of this, which is the
EXTRA CELLULAR fluid of the body, is called
HOMEOSTASIS
Concept by Walter Canon
Bottom line in Physiology:
Maintain Homeostasis
• Process of maintaining the composition of the internal body
compartments within fairly strict limits (ion concentrations,
pH, osmolarity, temperature etc).
• Require regulatory mechanisms to defend against changes
in external environment and changes due to activity.
• Cellular homeostasis - intracellular fluid composition
• Organismal homeostasis - extracellular fluid composition.
• Control system designed to maintain level of given variable
(concentration, temperature, pressure) within defined
• Feedback loops  Negative & Positive
•
• Negative feedback loop requires 
• Sensor (Detector): specific to variable needing to
be controlled
• Comparator (Control system): reference point
for sensor to compare against
• Effector: if sensor  comparator  Error Signal
 restore
variable to desired level
• Biofeedback systems in maintaining homeostasis
Controlled condition : eg body temp.
Control centre
(COMPARATOR)
Sets range of normal
Effector structure that receives
out put from control centre
values  SET POINT
Receptor
response
(sensor/detector)
stimulus
Feed back systems
• Negative feedback of Blood Pressure (BP)
• Negative feedback: BP regulation; CO2 regulation of breathing; body
temp. control; ADH & water retention by kidneys
Controlled condition : eg BP 120/80.
•
Control centre
Effector
(heart & blood vessels)
receptor
BP
disturbance
Negative feedback
Control of BP
-Ve Feed back control
of body temperature
Properties of negative feed back systems
• 1. They have a GAIN Effectiveness
• 2. Usually fast response
• 3. Incomplete correction  leaves behind an ERROR
•
Ideal Systolic BP : 120mmHg
•
Stimulus(shock) changes BP to 60mmHg
•
Coorected BP after feed back mechanism : 90mmHg
•
ERROR: 30 mmHg
• Positive feedback system
effector
controller
Response +++
receptor
stimulus
+++
• Positive feedback
• Normal labour
• Other examples:
• Action potential
• Coagulation of blood :
cascade
• Factors that affect performance of
homeostasis mechanisms
• Aging
• Severe environmental conditions beyond
control
• Nutrition status
• Disease
• Failure to maintain homeostasis:
disease
Disturbed
internal environment
Signs: observed by doctor
Symptoms: pts. complaints
diagnosis
investigations
Homeostasis
not restored
Morbidity/
death
failure
treatment
success
homeostasis restored
Maintenance of constancy of the
Internal Environment
Recapitulate
• 1. Internal environment with egs
• 2. Homeostasis
• 3. Feed back loops- -ve and + ve with egs
• 4. What happens when homeostasis is disturbed