intriduction to physiology [Autosaved].pptx

Introduction to Physiology

1. INTRODUCTION OF PHYSIOLOGY BY DR.EUSIVIA PASI MPT COMMUNITY REHABILITATION

2. CONTENTS Introduction – What is Physiology? Branches of Physiology Physiological Systems Levels of Organization of living organisms Physiological Organ systems in the human body Homeostatic Regulation Negative Feedback Mechanisms Positive Feedback Mechanisms Structure and function of a cell Cell membrane Nucleus and its chromosomes Cytoplasm and its organelles Junctional complexes; cell junction Apoptosis- programmed cell death

3. PHYSIOLOGY The term Physiology is a combination of two Greek words Physis means nature Logos means science or study Physiology is the science of studying the functional activities and its mechanisms in biological body BRANCHES OF PHYSIOLOGY Applied Physiology Clinical Physiology Nutrition Physiology Neuro Physiology Cardiovascular Physiology Respiratory Physiology Exercise Physiology Pathophysiology Cellular Physiology Renal Physiology

4. HISTORY OF PHYSIOLOGY GALEN was the first to perform experiments to understand the function of the body ; so known to be the father of physiology The first “ physiologist” of the world ,in the modern sense , was WILLIAM HARVEY . In the 17 th century William Harvey first describes the circulatory system and its interaction with the body CLAUDE BERNARD ( 1813- 1878) propounded the concept of ‘milieu interieu ’ or internal environment and established physiology as the scientific basis of medicine. THE FATHER OF MODERN PHYSIOLOGY IS THE FRENCH PHYSIOLOGIST CLAUDE BERNARD

5. ORGAN SYSTEMS OF THE HUMAN BODY SYSTEM NAME ORGANS (OR TISSUES) FUNCTION(S) 1 CIRCULATORY Heart, blood vessels, blood Transport of materials all cells of the body 2 DIGESTIVE Stomach, intestines,liver,pancreas Conversion of food into particles that 3 ENDOCRINE Thyroid gland, adrenal gland etc. Coordination of body function through synthesis and release of regulatory molecules 4 IMMUNE Thymus, spleen, lymph nodes Defence against foreign invaders 5 INTEGUMENTARY Skin Protection from external environment 6 MUSCULOSKELETAL Skeletal muscles ,bones Support and movement 7 NERVOUS Brain, spinal cord Coordination of body function through electrical signals and release of regulatory molecules 8 REPRODUCTIVE Ovaries and uterus ,testes Production of the species 9 RESPIRTORY Lungs,airways Exchanges of oxygen and carbon dioxide between the internal and external environment 10 URINARY Kidneys ,bladder Maintenance of water and solutes in the internal environment ,waste removal

6. WHY DO WE SHIVER , WHEN WE FEEL COLD ?

7. HOMEOSTATIC REGULATION Homeo : same ; stasis : Stay( maintenance of a constant internal environment) 19 th century , CLAUDE BERNARD was first recognized the importance of maintaining a stable Internal environment Homeostatic mechanisms A term coined by W.B.Cannon an American physiologist) The adjustments in physiological systems that are responsible for the preservation of homeostasis are referred to as homeostatic regulation Feedback system : is a cycle of events in which the status of a body condition is monitored , assessed , changed and re-monitored. Receptor(sensitive to a particular stimulus ) Control center(Brain) Effector (receive signals from control center) Are broadly controlled by two mechanisms.

8. MILIEU INTERIEU MILIEU- environment INTERIEUR- internal THE INTERNAL ENVIRONMENT or milieu interieur Extracellular Importance fluid 19 th French psychologist Concept of internal environment of an organisms Blood – as the internal environment. All the cells in the body live in the same environment ,the ECF They get nutrition from it and discharge their waste products in it

9. REGULATORY MECHANISM NEGATIVE FEEDBACK MECHANISM A corrective mechanism involving an action that directly opposes a variation from normal limits The initial stimulus produces a response that depresses the stimulus i.e. stimulus and response are opposi te to each other This system regulates conditions in the body that remain fairly stable over long periods.

10. POSITIVE FEEDBACK MECHANISM An initial disturbance in a system sets off a chain of events that increases the disturbances even further A process in which the body senses a change and activates mechanisms that accelerate or increase that change The initial stimulus produces response that reinforces(exaggerates ) the original stimulus Child birth (parturition reflex) Uterine contractions due to oxytocin Baby’s head pushes against the cervix –stretch Send impulses to the uterus Stimulates further contraction of the uterus Pushing the baby out Milk ejection reflex

11. CELL STRUCTURE AND FUNCTION

12. CELL MEMBRANE or PLASMA MEMBRANE or UNIT MEMBRANE Basic living unit of structure and function of the body >100 trillion cells in body Very small ( 10 -5 μ m in diameter ) Highly organized Variety of shapes and sizes Each types of cells has a special function. 3 Principal part - plasma ( cell) membrane - Nucleus and its chromosomes - Cytoplasm & organelles The cytoplasm contains the major cell organelles and a fluid called CYTOSOL

13. PLASMA (CELL) MEMBRANE 75 to 100 Angstrom(Ặ) thickness Surrounds , hold cell together and gives its form Not solid Separates cell’s internal structures from extracellular environment Is selectively permeable , and controls passage of materials into and out of cell Participates in intracellular communication Composed of ; Double layer of phospholipids(hydrophobic /hydrophilic parts) Proteins span , or partially span the membrane Negatively charged carbohydrates attach to the outer surface Plasma membranes made up of phospholipids, proteins, cholesterol, and carbohydrates These components give a fluid character to the membranes Cholesterol and proteins are embedded in the bilayer that gives the membrane a mosaic look.

14. Components of Plasma Membrane Phospholipid:  The main fabric of plasma membrane Proteins:  Inner or outer and embedded within phospholipid layers Cholesterol:  Between phospholipids and phospholipid bilayers Carbohydrates:  Attached to proteins on outside membrane layers Role of the components of Plasma Membrane Phospholipids Phospholipids have a hydrophobic head and fatty acid tail, form a bilayer separating the cell from the outside. They are fluid and components can move around freely Permeable to small and  non-polar molecules Impermeable to large molecules and ions and prevent these substances from passing thorough

15. PROTEINS 60-70 % of the dry weight of the membrane , and are of 2 types L ipoproteins ( proteins containing lipid ): function as enzymes and ion channels Glycoproteins ( proteins containing carbohydrates):function as receptors for hormones and neurotransmitters; play a role in body’s immune response .They stabilize the membrane and are responsible for  intercellular communication Integral (intrinsic)Proteins: l ocated in the inner surface of the membrane. Serve mainly as ‘enzymes’ These proteins form channels to allow the movement of large molecules and ions across the  hydrophobic  layer of the membrane Peripheral (extrinsic)Proteins:  These are found embedded in a single leaflet of the membrane. They carry signals from one segment of the membrane and relay it to another. Contribute to the cytoskeleton.

16. Transmembrane proteins: serve as Channels, through which ions or small water soluble substances can diffuse Carriers, which passive ly and actively transport polar substance or ions to move across the lipid layer Pumps, which actively transport ions across the lipid layer Receptors , which when activated initiate intracellular reactions. They serve as cellular recognition sites. Each type of receptor recognizes and binds a specific type of molecule Enzymes that catalyze specific chemical reactions of the cell Cholesterol It helps the plasma membrane to retain the fluidity. It is present between the  phospholipids  and prevents the compaction of hydrophilic tails at low temperatures and their expansion at high temperatures.

17. FUNCTION OF CELL MEMBRANE Protective -it forms outermost boundary of the cell organelles Digestive –takes in food and excretes waste products Property of selective permeability – i ) non-polar charged uncharged molecules (gases like O2,CO2 and N2,lipids, steroid hormones,alcohol )can dissolve in non-polar regions of the membrane and move rapidly across the membrane ii) polar molecules (water soluble substances :ions, glucose,urea etc )have lower solubility ,penetrate the membrane more slowly iii) chemical and physical characteristics of the membrane control the free passage of ions and molecules into and out of the cell 4 . Insulating properties: it act as the dielectric material of a charged condenser ,the cell membrane has a very high insulating value It provides a frame work for the arrangement of an ordered sequence of protein molecules (enzymes, pumps, receptors, ions,channels,co-factors,carriers )in a functionally meaningful pattern It links adjacent cells together by junctional complexes to form tissues

18. STRUCTURE (FLUID MOSAIC MODEL)

19. FLUID MOSAIC MODEL Fluid mosaic model was proposed by  S.J. Singer  and  Garth L. Nicolson This model explains the structure of the plasma membrane The Fluid Mosaic Model states that membranes are composed of a  Phospholipid Bilayer  with  various protein molecules  floating around within it. The ‘ Fluid ’ part represents how some parts of the membrane can move around  freely , if they are  not attached to other parts of the cell . The ‘mosaic’ part illustrates the  ‘patchwork’ of proteins  that is found in the Phospholipid Bilayer. ‘Fluid’-th e individual phospholipid and protein molecules move around within their layer ‘Mosaic ’ – described the pattern produced by the scattered protein molecules when the surface of the membranes is viewed from above

20. GENERAL CELL STRUCTURE AND FUNCTION COMPONENT STRUCTURE FUNCTION Plasma (cell) membrane Membrane composed of double layer of phospholipids in which proteins are embeded Surrounds, hold cell together and gives its form;control passage of materials into and out of cell CYTOPLASM Fluid, jelly like substance b/w cell membrane & nucleus in which organelles are suspended Serves as matrix substances in which chemical reaction occur NUCLEUS - NUCLEAR ENVELOPE Double- layered membrane that surrounds nucleus , composed of proteins and lipid molecules Supports nucleus and control s passage of materials b/w nucleus and cytoplasm - NUCLEOLUS Dense nonmembranous mass composed of protein and RNA molecules Produces ribosomal RNA for ribosomes -CHROMATIN Fibrous strands composed of protein and DNA Contains genetic code that determine which protein( including enzymes) will be manufactured by the cell

21. CONSISTS OF CELL MEMBRANE

22. NUCLEUS STRUCTURE It is a spherical structure (10 μ m diameter) Surrounded by relatively permeable membrane called NUCLEAR MEMBRANE (or envelope), It is made up of chromosomes Gene is a portion of DNA molecule which carries a complete blue print for all heritable species During cell division ,pairs of chromosomes become visible ,between cell divisions the irregular clumps of dark material called CHROMATIN are presence It contains a NUCLEOLUS which is densest Nucleoli are most prominent and numerous in growing cells, They synthesize the RNA for the ribosomes FUNCTION DNA in nucleus serves as ‘ template’(block) for synthesis of RNA Genes are units of hereditary characteristics It is concerned with cellular reproduction and multiplication

23. CYTOPLASM AND ORGANELLES The aqueous content of cell (fluid, jellylike substance)that lies between cell membrane and nucleus in which organelles are suspended Serves as matrix substances in which chemical reaction occur ‘ cytosol ‘is the term used to describe fluid portion of the cytoplasm

24. 1. ENDOPLASMIC RETICULUM (ER): it is a complex series of tubules whose walls are made up of unit membrane Types 1. Agranular or smooth ER : contains no granules a) it is the site of steroid (adrenocortical hormone ) synthesis in steroid secreting cells and site of detoxification processes in other cells b) Sarcoplasmic reticulum ,it plays important role in skeletal and cardiac muscle 2. Granular or rough ER or ergastoplasm Contains granules called ribosomes, which are attached to the cytoplasmic side of the membrane ,3-5 ribosomes clump together to form polyribosomes or polysomes It is the site of protein synthesis Free ribosomes are also found in the cytoplasm ,

25. GOLGI COMPLEX (OR GOLGI BODIES) It is a collection of membranous tubules and vesicles Prominent in actively secreting gland cells FUNCTIONS Wrapping and packaging department of the cell Produces secretion granules i.e membrane enclosed complexes, store hormone and enzymes in protein secreting cells; it packages proteins iii. Site of formation of lysosomes iv. It adds certain carbohydrates to proteins to form glycoprotein

26. MITOCHONDRIA STRUCTURE Length 5-12μm; diameter 0.5 -1μm; filamentous or globular in shape occur in variable numbers Made up of outer membrane and inner membrane Inner membrane folded to form cristae Outer membrane :studded with enzymes concerned with ‘biological oxidation’ Interior (matrix) of mitochondria contains enzymes concerned with ‘citric acid cycle’ and ‘respiratory chain oxidation’ 5. Inner membrane contains (ATPase) and other enzymes concerned with synthesis and metabolism of ATP FUNCTION Are power generating units of the cells Contains DAN and can synthesize proteins

27. 4. LYSOSOMES STRUCTURE Large irregular structure surrounded by unit membrane and found in the cytoplasm;250-750nm in diameter It is filled with large number of small granules ,5-8 nm in diameter contain variety of enzymes , called Lysozymes The interior is kept acidic (near pH 5.0) by the action of proton pump or H+ or ATPase Lysosomes are all acid hydrolases FUNCTIONS Acts a form of digestive (lytic) system for the cell Engulf worn out components of the cells Engulf exogenous substances e.g bacteria and degrade them Lysosomes are called as SUICIDAL BAG

28. 5. PEROXISOMES Structure is similar to lysosomes but with different chemical composition It contain oxidases( enzymes that remove hydrogen atom from organic substances to produce H2O2) They consume oxygen in small amounts They destroy certain products formed from oxygen, esp hydrogen peroxide ,that can be toxic to the cells, hence the name peroxisomes

29. Cytoplasmic organelles;Structure and function Component Structure Function Endoplasmic reticulum System of interconnected membrane- forming canal and tubules AGRANULAR(Smooth)ER metabolises nonpolar compounds & stores Ca2+in straited muscles cells;GRANULAR (rough)ER assists in protein synthesis Ribosomes Granular particles composed of protein and RNA Synthesis proteins Golgi complex Cluster of flattened membranous sac Synthesizes carbohydrates and packages molecules for secretion. Secretes lipids and glycoprotein Mitochondria Membranous sac with folded inner partitions Release energy from food molecules and transform energy into usable ATP Lysosomes Membranous sacs Digest foreign molecules and damaged organelles

30. 6. CENTRIOLES OR CENTROSOMES STRUCTURE Are two short cylinders called ‘ centrioles ’ visible only during cell division Are located at each pole near the nucleus and arranged at right angels to each other Tubules in group of three(triplets) run longitudinally in the walls of the centrioles FUNCTION They are concerned with the movement of the chromosomes during cell division

31. CYTOSKELETON

32. All cells have a system of fibers called c ytoskeleton that maintain the structure of the cells. The cytoskeleton is a network of fibers extending throughout the cytoplasm It allows a cell to change shape and also permits its movement They provides mechanical support and maintains shape of the cell Also plays a role in cell motility by interacting with motor protein The Cytoskeleton is composed of 3 well defined- filamentous structure – 1. Microtubules 2.Microfilaments and 3. Intermediate filaments with distinct function .

33. MICROTUBULES AND MICROFILAMENTS Microtubules are long unbranched hollow tubes approx. 25nm in diameter Are the central structural supports both cilia and flagella Make up structures or tracts on which chromosomes ,mitochondria and secretion granules move from one part of the cell to another Microfilaments are long solid 4-6nm in diameter . They comprise the contractile protein actin and are most abundant at the edge of a cell They are responsible for cell motion Intermediate filament Diameter is about 10nm Made up of fibrous intermediate proteins Different cell types ,different intermediate filaments They have great tensile strength ,main function is to help the cells withstand mechanical stress Bears tension, reinforces cell shape, fix organization of certain organelles

34. FUNCTION Movement of the chromosomes Cell movement ;and provide mechanical support Processes that move secretion granules in the cell and Movement of proteins within the cell membrane Migration of skin cells during wound healing

35. 8. SECRETION GRANULES Secretory granules are specialized intracellular organelles that serve as a storage pool for selected secretory products. Secretory granules  function as storage compartments for secretory products and are the main organelles involved in regulated secretion. Contain specific proteins and other macromolecules that are destined for secretion into the extracellular space. Membrane enclosed complexes, which store hormones and enzymes in protein secreting cells It packages proteins

36. JUNCTIONAL COMPLEXES :CELL JUNCTION Connection between the neighboring cells or contact between cell and extracellular matrix It is a type of structure that exist within the tissue of some multicellular organisms

37. The different types of cell junctions Tight junctions (blue dots) between cells are connected areas of the plasma membrane that stitch cells together. Adherens junctions (red dots) join the actin filaments of neighboring cells together. Desmosomes are even stronger connections that join the intermediate filaments of neighboring cells. Hemidesmosomes (light blue) connect intermediate filaments of a cell to the basal lamina, a combination of extracellular molecules on other cell surfaces. Gap junctions (yellow) are clusters of channels that form tunnels of aqueous connectivity between cells.

38. The cells are associated into tissues by various means Tight Junction: -In this membrane of two cells become apposed and outer layers of the membranes fuse strongly -Is seen in the apical margins of cells in epithelium such as in the intestinal mucosa ,walls of the renal tubules, and the choroid plexus -Forms a barrier to the movement of ions and other solutes from one side of the epithelium to the other

39. 2. Desmosomes or Adherens junction Desmo mean band Two membranes are separated by a 150 -350 Ȧ space. There is dense accumulation of proteins on both the surfaces of the membrane with fibers extending from the cytoplasmic surface of each membrane into the cell Transmembrane glycoproteins called cadherins join the cells. Holds adjacen t cells firmly together in areas that are subjected to stretching e,g skin Also resist separation during various contractile activities such as when food moves through the GIT

40. 3. Gap Junction or Nexus: There is 2nm to 20nm space between the opposing membranes Gap is filled with densely packed particles through which each appears a channel (tiny fluid filled tunnels) that connects the two cells The diameter of each channel is regulated by intracellular  Ca 2+ ,pH and voltage It permits rapid propagation of electrical potential changes from one cell to another e.g,cardiac and smooth muscle cells It permits the direct transfer of ions and other small molecules ( sugars,amino acids) between the cells without traversing the extracellular space

41. CELL ADHESION MOLECULES (CAMs) Cells are attached to each other by cell adhesion molecules(CAMs) They transmit signals into and out of the cell These adhesion proteins ( viz,laminin,integrin,IgG , cadherin ,selectin) play an important role in: Embryonic development Formation of the nervous system Holding tissues together Inflammation and wound heling, and metastasis of tumours , Cells with abnormal CAMs have a higher rate of APOPTOSIS

42. APOPTOSIS :PROGRAMMED CELL DEATH Apo means ‘away’ and Ptosis means ‘fall’ It is a Greek word which means loosening or falling APOPTOSIS is a process of programmed cell death in which body cells die and get absorbed (phagocytosed)under genetic control Cell’s own gene plays an active role on its death ,therefore also called as cell suicide MECHANISMS: apoptosis is initiated by Environmental processes such as inflammation Internal stimuli-lack of oxygen and nutrients Fas , a transmembrane protein produced by natural killer cells and T-lymphocytes Tumour necrosis factor

43. The pathway initiating apoptosis is Activation of group of cysteine proteases inactivate enzymes (together called as (CASPASES)within the mitochondria The activated apoptotic gene causes the cell to undergo DNA fragmentation ,condensation of cytoplasm and chromatin Finally the cell breaks up and remnants are removed by phagocytes

44. PHYSIOLOGICAL SIGNIFICANCE Plays an important role during embryonal development and also in adulthood It removes un-needed cells It is responsible for regression of duct system during sex differentiation in the foetus It is responsible for degeneration and regeneration of neurons within the CNS and for the formation of the synapse It is responsible for removal of inappropriate clones of immune cells It is responsible for cyclical shedding of endometrium at the time of menstruation ; and It is responsible for cell shed from the tip of the villi in the small intestine

45. STUDY QUESTION CELLULAR CYTOSKELETON MILIEU INTERIEU HOMEOSTATIC REGULATION JUNCTIONAL COMPLEXES PEROXISOMES LYSOSOMES CELL ADHESION MOLECULE NEGATIVE VERSUS POSITIVE FEEDBACK MECHANISMS FLUID MOSAIC MODEL