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  1. Nerve – Muscle physiology. By-Karanveer,Shivam,Ram,Sachin Dushyant,Shivanshu,Dharmendra Group No.-218
  2. Blood-the “River of Life” Blood is the only fluid tissue in the human body. Blood is classified as a connective tissue. Blood carries nutrients, waste, and body heat through blood vessels. • Components of blood – Living cells • Formed elements – Non-living matrix • Plasma
  3. Blood Composition If blood is centrifuged – Erythrocytes sink to the bottom (45% of blood, a percentage known as the hematocrit) – Buffy coat contains leukocytes and platelets (less than 1% of blood) • Buffy coat is a thin, whitish layer between the erythrocytes and plasma – Plasma rises to the top (55% of blood) The formed elements (blood cells) make blood heavier and 5 times thicker (more viscous) than water.
  4. Figure 10.1 (2 of 2) Blood
  5. Physical Characteristics of Blood • Color range – Oxygen-rich blood is scarlet red – Oxygen-poor blood is dull red • pH must remain between 7.35– 7.45 Acidosis (pH7. 2) Death (pH 7)
  6. Physical Characteristics of Blood • Blood temperature is slightly higher than body temperature at 100.4°F • In a healthy man, blood volume is about 5–6 liters or about 6 quarts • Blood makes up 8% of body weight
  7. Functions of Blood • Functions include (More details on next 3 slides) – Distributing substances – Regulating blood levels of substances – Protection
  8. Distribution Functions • Delivering O2 and nutrients to body cells • Transporting metabolic wastes to lungs and kidneys for elimination • Transporting hormones from endocrine organs to target organs
  9. Regulation Functions • Maintaining body temperature by absorbing and distributing heat • Maintaining normal pH using buffers; alkaline reserve of bicarbonate ions • Maintaining adequate fluid volume in circulatory system
  10. Protection Functions • Preventing blood loss – Plasma proteins and platelets initiate clot formation • Preventing infection – Antibodies – Complement proteins – WBCs
  11. Blood Plasma Composition • Composed of approximately 90% water • Includes many dissolved substances – Nutrients – Salts (electrolytes) – Respiratory gases – Hormones – Plasma proteins – Waste products
  12. Blood Plasma • Plasma proteins – Most abundant solutes in plasma – Most plasma proteins are made by liver – Various plasma proteins include • Albumin—regulates osmotic pressure • Fibrinogen: Clotting proteins—help to stem blood loss when a blood vessel is injured • Globulins: Antibodies— help protect the body from pathogens
  13. Blood Plasma: Homeostatic imbalances • Acidosis – Blood becomes too acidic • Alkalosis – Blood becomes too basic • In each scenario, the respiratory system and kidneys help restore blood pH to normal
  14. Formed Elements • Erythrocytes – Red blood cells (RBCs) • Leukocytes – White blood cells (WBCs) • Platelets • Cell fragments
  16. WHAT IS CELL MEMBRANE ? 34 ✓ The cell membrane (also called the plasma membrane or plasmalemma) is a biological membrane separating the interior of a cell from the outside environment ✓ It appears in thin sections with the electron microscope as a triple-layered structure about 7.5–10 nanometers thick ✓ Term coined by C. Nageli and C. Cramer in 1855, and Plasmalemma coined by J. Q. Plowe in 1931
  17. CELL MEMBRANE ❖ The cell membrane is flexible and allows a unicellular organism to move 35
  18. CHEM ICAL COMPOSITION 36 1.Lipids -four major classes of lipids are commonly present in the plasma membrane: phospholipids (most abundant), spingolipids, glycolipids and sterols (e.g. cholesterol). All of them are amphipathic. Cholesterol is abundant in mammalian cell and is absent in prokaryotic cells 2.Proteins-plasma membrane contains about 50% protein. Amount and type is variable. Myelin cells contains about 25% protein internal membranes of chloroplast and mitochondria contains 50% protein. Proteins of plasma membranes are of two types ectoproteins and endoproteins. Plasma membranes contains structural proteins, transport proteins and enzymes. Some of them acts as receptors.
  19. C O N T … 37 (enzymes present in the plasma membrane are Acetyl phosphatase, acid phosphatase, ATPase, RNAase, maltase, lactase, phospholipase etc) 3. Carbohydrates- they are present only in the plasma membrane and are present exterior (glycoproteins) or polar end of phospholipids at the external surface of plasma membrane
  20. PHOSP HO L IPIDS 38 𝗈 Phospholipids (PL) molecule has a polar head and nonpolar tails 𝗈 The polar head is charged and hydrophilic (loves water) facing outward, contains a – PO4 group & glycerol 𝗈 The nonpolar tails are hydrophobic (hates water) facing inward contains 2 fatty acid chains that are nonpolar 𝗈 When PL placed in water form spherical bilayer
  22. MEMBRANE CHOLESTEROL 𝗈 The amount of cholesterol may vary with the type of membrane 𝗈Plasma membranes have nearly one cholesterol per phospholipid molecule 40
  25. FUNCTIONS OF PLASMA MEMBRANE Keeps a cell intact Protective barrier Regulate transport in & out of cell (selectively permeable) Small lipid-soluble molecules, e.g. oxygen and carbon dioxide can pass easily Water can freely cross the membrane 43
  26. FUNCTIONS OF PLASMA MEMBRANE… Ions and large molecules cannot cross without assistance Allow cell recognition Provide anchoring sites for filaments of cytoskeleton Provide a binding site for enzymes Interlocking surfaces bind cells together (junctions) Contains the cytoplasm (fluid in cell) 44
  27. MEMBRANE STRUCTURE 𝗈 Membranes consist of a phospholipid bilayer combined with a variety of proteins in a fluid mosaic arrangement 𝗈 The surfaces of cell membranes are hydrophilic (water-loving); the interiors are hydrophobic 45
  28. FLUID MOSAIC MODEL 25 𝗈 Widely accepted model 𝗈 According to S. J . Singer and Garth Nicolson 1972, the biological membranes can be considered as a two- dimensional liquid where all lipid and protein molecules diffuse more or less freely 𝗈 Singer studied phospholipid bilayers and found that they can form a flattened surface on water, with no requirement for a protein coat 𝗈 It occurs in form of globular protein