The document discusses the structure and function of the cell membrane. It begins by defining the cell membrane as a biological membrane that separates the interior of the cell from the outside environment. It then describes the chemical composition of the cell membrane, which includes lipids, proteins, and carbohydrates. Phospholipids are the most abundant lipid and form a bilayer structure with a hydrophilic head and hydrophobic tails. The cell membrane regulates what enters and exits the cell and also provides structure and anchors cell proteins and cytoskeleton. It functions in transport, protection, and cell recognition. The fluid mosaic model describes the cell membrane as a fluid bilayer with embedded proteins that can move laterally.

1. Nerve – Muscle
physiology.
By-Karanveer,Shivam,Ram,Sachin
Dushyant,Shivanshu,Dharmendra
Group No.-218

20. 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

21. 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.

22. Figure 10.1 (2 of 2)
Blood

23. 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)

24. 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

25. Functions of Blood
• Functions include (More details on next 3
slides)
– Distributing substances
– Regulating blood levels of substances
– Protection

26. 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

27. 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

28. Protection Functions
• Preventing blood loss
– Plasma proteins and platelets initiate clot
formation
• Preventing infection
– Antibodies
– Complement proteins
– WBCs

29. Blood Plasma
Composition
• Composed of
approximately 90%
water
• Includes many
dissolved substances
– Nutrients
– Salts (electrolytes)
– Respiratory gases
– Hormones
– Plasma proteins
– Waste products

30. 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

31. 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

32. Formed Elements
• Erythrocytes
– Red blood cells (RBCs)
• Leukocytes
– White blood cells (WBCs)
• Platelets
• Cell fragments

33. CELL MEMBRANE
1

34. 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

35. CELL MEMBRANE
❖ The cell membrane is flexible
and allows a unicellular
organism to move
35

36. 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.

37. 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

38. 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

39. PHOSPHOLIPIDS….
39

40. MEMBRANE CHOLESTEROL
𝗈 The amount of cholesterol
may vary with the type of
membrane
𝗈Plasma membranes have
nearly one cholesterol per
phospholipid molecule
40

41. STRUCTURE O F THE C E L L
MEMBRANE

42. MEMBRANE COMPONENTS
42

43. 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

44. 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

45. 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

46. 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

47. FLUID MOSAIC MODEL…..
47