Introduction to Human Physiology

1. Introduction to Human Physiology What is physiology? It is the science that deals with the function of organs and systems and the way they do this functions and the way they integrate.

2. Exams and marks • 250 marks: • 125 final exam • 45 practical • 30 oral • 40 midterm • 10 shock exam

3. Man and the environment • External environment: (variable surroundings) • The environment man lives in, interacts with (benefits and hazards) • Major environmental factors are: oxygen, water, food, physical factors, social factors, micro organisms and parasites.

4. Body-Fluid Compartments H20: 60% of TB.Wt. in adult male. 75% of TB.Wt in infants Less than 60% in adult female and obese people TBW is disributed as:

6. Body water lungs Intravascular fluid=5% Stomach& intestine Interstitial fluid=15% Cell water= 40% Capillary wall Kidneys &skin

7. The concentration of the minerals in the intracellular fluid is different from the concentration of them in the extra cellular fluid. • The total blood volume is 8% of TBWt

9. Determination of the volumes of water in the body Fick`s principle Indicator: inert, non toxic, not utilized by tissues. • Known amount of indicator is injected intravenously 9gm • Time is allowed for uniform diffusion • A sample is withdrawn to determine the concentration in the plasma 3gm/L Volume of the compartment (volume of the distribution) = amount injected / concentration in plasma 9 gm/3gm/L= 3L

10. Application: 1- TBW: Heavy water (D2O) deuterium oxide 2- ECF: Inulin (polysaccharide fiber) or Na thiocyanate (NaSCN) 3- Plasma: Evan`s blue or radioactive plasma proteins 4- ICF: TBW- ECF 5-ISF: ECF-Plasma volume

11. Homeostasis • The internal environment is the interstitial fluid that surrounds the cells

12. The internal environment • The human body consists of organs& tissues that are formed of cells. • The cell is the smallest unit of life. • The cell is surrounded by interstitial fluid (Internal Environment). • The composition of the internal environment should remain constant within narrow limits.

13. Internal environment • All the life processes have only one goal, that is to keep the internal environment constant, and this fixity of the internal environment is necessary condition for life

14. Homeostasis: • It is all the physiological processes that are carried out by all body systems. • It is to insure that chemical and physical structure of the internal environment is kept constant in spite of external (e.g.: temp, oxygen tension, pressure) or internal (e.g.: increased muscular activity) changes. • It deals with all automatic reactions which take place to correct all deviations from normal • It is a necessary condition for the existence • Failure of homeostasis often leads to diseases and death.

15. Body water lungs Intravascular fluid=5% Stomach& intestine Cell water= 40% Interstitial fluid=15% Capillary wall Kidneys &skin Cell membrane

16. ICF ISF plasma organs external environment internal environment Exchange and communication are key concepts for understanding physiological homeostasis.

18. Homeostasis: The body’s ability to maintain a stable internal environment. Toxic Chemicals Trauma Viruses Bacteria Cancer Autoimmune Disease Sickle cell anemia Diabetes

19. Example for homeostasis • Cells consumes glucose & O2 • Cells takes glucose & O2 from ISF (1st exchange through cell membrane) • ISF takes these substances from blood (2nd exchange through capillary wall) • Blood brings new nutrients & O2 from systems from external environment

20. Cell • Unit of function of living organism • Cells with similar properties….… tissue. • Different tissues……organs. • Complementary organs…..systems • The structure of the cell varies according to the function (specialization) • No typical cell • All cells are formed of mass of protoplasm surrounded by cell membrane

21. The Cell Membrane *Very thin (7.5-10 nm) *Elastic *Semipermeable * Dynamic * EM: lipid bilayer & proteins *Made of proteins 55%, phospholipids 25%, cholesterol 13%,other lipids 4%&CHO 3%, *amphipathic (hydrophilic & hydrophobic)

22. Phospholipids Flexibility & selective permeability • Fatty acid tails • hydrophobic • Phosphate group head • hydrophilic • Arranged as a bilayer Phosphate Fatty acid

23. Phospholipid bilayer polar hydrophilic heads nonpolar hydrophobic tails polar hydrophilic heads

24. Protein: *Hydrophilic & hydrophobic *Integral & peripheral • Cholesterol: permeability & toughness • CHO: recognition sites & attach cells together Glycoprotein Glycolipid Cholesterol Peripheral protein

25. Functions of membrane proteins • 1- structural ptns • 2- passive channels: ungated & gated(voltage / ligand) • 3- carriers for facilitated diffusion • 4- carriers for active transport (uniport /symport/ antiport) • 5- receptors: number & sensitivity change • 6- enzymes • 7- identity ptns • 8-intercellular connections: a. binding j: tight & desmosomes b. gap j • 9- cell adhesion molecules • 10- fixation of cytoskeleton

26. Many Functions of Membrane Proteins Outside Plasma membrane Inside Transporter Enzymeactivity Cell surfacereceptor Cell adhesion Cell surface identity marker Attachment to thecytoskeleton

27. Intercellular connectionsbinding and channel junctions

28. Gap junctions: for rapid propagation of electrical activityallow rapid passage of ions and molecules up to MW1000 diameter is regulated by Ca, pH, hormones and drugs

29. Membrane carbohydrates • Play a key role in cell-cell recognition • ability of a cell to distinguish one cell from another • antigens • important in organ & tissue development • basis for rejection of foreign cells by immune system

30. Movement across the Cell Membrane

31. Diffusion • All molecules are in constant motion • Diffusion: • Passivemovement from highlow concentration

32. Diffusion across cell membrane • 1- simple diffusion: with concentration gradient- no energy- no carrier Diffusion rate α con gradient x surface area x temp /√mol wt x distance 1- through lipid bilayer: Lipid soluble sub Water Lipid insoluble sub (urea) 2- through protein channels: Ions electrically charged hydrated Each protein channel is specific through diameter, shape, electrical charge & gates Selective permeability gating • 2- facilitated diffusion: with conc. gradient, passive, carrier for large molecules Characters: Specificity competition rate increases with concentration gradient up to maximum more sensitive to temperature

34. AS Biology, Cell membranes and Transport

35. high low Facilitated Diffusion • Diffusion through protein channels • channels move specific molecules across cell membrane • no energy needed facilitated = with help open channel = fast transport

36. Osmosis is diffusion of water • Diffusion of water from high concentration of water to low concentration of water • across a semi-permeable membrane • The pressure necessary to stop solvent mol movements= osmotic pressure • The numbers of particles per unit volume of fluid • Measured in mmHg • Osmole osmolarity osmolality

37. The osmolarity of ICF=that ECF=300 mosmol • 280 mosmol is due to Na, Cl & HCO3 • 20 mosmol is due to protein • Tonicity: is the osmolality of a solution relative to the plasma • Plasma proteins of blood is called oncotic pressure. It is important for capillary circulation &regulation of ECF

38. hypotonic hypertonic Concentration of water • Direction of osmosis is determined by comparing total solute concentrations • Hypertonic - more solute, less water • Hypotonic - less solute, more water • Isotonic - equal solute, equal water water net movement of water

39. Donnan effect • The protein anions inside the cells are non diffusible hinder the diffusion of diffusible cations • More osmotically active particles inside the cell • The cell tends to swell • But the Na+/ K+ pump prevents cell rupture

40. Donnan effect 4K+ 4K+ 4Cl- 2Cl- & 2 Ptn- 3Cl- 3Cl-& 2Ptn- 3K+ 5K+

42. low high Active Transport • Against concentration gradient • Needs carrier protein • Energy is needed conformationalchange ATP “The Doorman”

43. Active transport • Many models & mechanisms ATP ATP antiport symport

44. Active transport • 1ry active: *eg Na+/K+ pump *α &β subunits *α subunit contains 2 binding sites for K+ on the outside & 3 binding sites for Na+ on the inside & an ATP binding site *β subunit has ATPase activity. • 2ry active: *eg Glucose transport 2ry to active transport of Na 1st Na pumped out ….creates concentration gradient… Na & glucose bind a carrier…transports them to inside

46. Figure 5.13 Primary Active Transport: The Sodium–Potassium Pump In active transport, energy is used to move a solute against its concentration gradient. For each molecule of ATP used, 2 K+ are pumped into the cell and 3 Na+ are pumped out of the cell. K+ Outside of cell Sodium– potassium pump Inside of cell Na+

48. Getting through cell membrane • Passive Transport • Simple diffusion • diffusion of nonpolar, hydrophobic molecules • lipids • high  low concentration gradient • Facilitated transport • diffusion of polar, hydrophilic molecules • through a protein carrier • high  low concentration gradient • Active transport • diffusion against concentration gradient • low  high • uses a protein pump • requires ATP • Vesicular transport ATP

49. Transport summary simplediffusion facilitateddiffusion ATP activetransport