Introduction to Human Physiology Abdul Aleem Khan

1. Introduction to Human Physiology Abdul Aleem Khan

2. Le Milieu Intérieur And Homeostasis I and II

3. STRUCTURE FUNCTION WHAT IT “IS” HOW IT “WORKS”

4. What is human Physiology • A branch of science that deals with the functioning of Human body • How does the heart beat ? • How do we breathe ? • How do we see ? • How do we remember ? • How do we move ? • How do we reproduce?

5. To answer these global questions it is essential to understand that the functional unit of the body is the cell. • How cells (like muscle, nerve) function? • And how similar and dis-similar types of cells work together at various organisational levels (integration)  as a whole organism • All most all life processes are governed by laws of physics and chemistry

6. Divisions of Physiology • Integumentary 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) • Immune Physiology (system)

7. Various levels of structural organization Atoms Molecules Organelles Cells Tissues Organs Systems Organism

9. A Cell

10. Cell theory • The cell is the basic structural and functional unit of living organisms • The activity of an organism depends on both the individual and collective activity of its cells • The biochemical activities of cells are dictated by their specific subcellular structures (principle of complementarity) • Continuity of life has a cellular basis (cells come from cells)

11. Cell Diversity • There is really no “typical” cell. Cells have different shapes, different sizes, different functions, different life spans. • Stem cells is pluripotent. • Examples of Specialized cells: Many different types of blood cells Three different types of muscle cells Fat Storage cells Nerve cells that transmit electrical impulses Cells for reproduction

12. Cells internal Environoment

13. Claude Bernard (1813-1878) “La fixité du milieu intérieur est la condition de la vie libre.” “The fixity of the internal environment is the condition for free life.”

14. Internal Environment Claude Bernard in 1829 said: The proper functioning of the cells depends on precise regulation of the composition of their surrounding fluid. Surrounding fluid = Internal environment = Le Milieu interier

15. Internal Environment

16. Body water • Water is main solvent in living cells • Hydrophilic molecules dissolve in water • Hydrophobic molecules do not dissolve in water • Amphiphilic - molecule part hydrophilic/part hydrophobic Body Water Extracellular fluid (outside cells) Intracellular fluid (inside cells) Interstitial Fluid (outside blood vessels) Plasma (inside blood vessels)

17. Chemical composition of body Major Elements % body wt Oxygen 65% Carbon 18% Hydrogen 10% Nitrogen 3.4% Mineral Elements Sodium 0.17% Potassium 0.28% Chloride 0.16% Calcium 1.5% Magnesium 0.05% Phosphorus 1.2% Sulphur 0.25% Trace Elements Iron 0.007% Zinc 0.002% Water = 60% adult male = 50% adult female • Principal organic constituents • carbohydrates  sugars • fats  fatty acids • proteins  amino acids • nucleic acids  nuclotides

18. Organ system Interrelationship • Nutrients and oxygen are distributed by the blood • Metabolic wastes are eliminated by the urinary and respiratory systems

19. Co-ordination of Organ System

20. Homeostasis Maintenance of constancy of the Internal Environment Walter Cannon (1929)

21. Control center (Set point) Controlled variable Controlled variable Effector Control center Effector Sensor Control Systems Open Loop Systems Closed Loop Systems (Feedback Systems) Feedback Systems are of two types: 1. Negative feedback 2. Positivefeedback

22. Homeostasis Maintenance of constancy of the Internal Environment

23. Physiological variables maintained by controlled systems

24. 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 range following disturbance.

25. Disturbance Error signal Comparator (reference point) Controlled variable Effector Sensor Feedback loop 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

26. Homeostasic Setpoint • Homeostatic range -oscillation around setpoint • Change in setpoint 1. Acclimatization 2. Biorhythms

27. Negative feedback System The response reverses the original stimulus. Example:Blood pressure and blood glucose regulation The response enhances the original stimulus Example child birth Negative feedback System

28. Maintenance of body temperature • Composed of • Detector • Control system • Effector The effector response Decreases or increases the effect of the original stimulus

29. Negative feedback System Stimulus: change in BP Receptors: Baroreceptors Control Center: Brain Effector: Heart

30. Negative feedback System

31. Negative feedback System

32. Negative feedback System

33. Limitation of negative feedback • Negative feedback control is initiated after variable is disturbed • Amount of correction to be applied, is assessed by magnitude of error signal  incomplete correction • Overcorrection  oscillations in controlled variable • Disadvantages overcome by multiple regulatory mechanisms. Regulation of blood [glucose] Insulin   [glucose]blood Glucagon   [glucose]blood

34. disturbance + + controlled variable effector sensor Positive feedback • Negative feedback - error signal  reducesdeviation from reference point • Positive feedback - error signal  increasesdeviation from reference point (vicious circle) Error signal

35. Positive feedback System Stimulus: stretch of the uterus Receptors: stretch receptors (cervix) Control Center: Brain Effector: Uterus

36. Positive feedback System

37. Homeostasis • Homeostasis is the ability to maintain a relatively stable internal environment in an ever-changing outside world. • The internal environment of the body is in a dynamic state of equilibrium. • Concepts of homeostasis dynamic. • Chemical, thermal, and neural factors interact to maintain homeostasis.