2. Human Physiology
Branch of medical science
Dealing with the functions & activities
Human and their parts
Including physical & chemical processes
Scientific study of
Normal function &Mechanism
Living systems
3. Human physiology
Studies of normal faction & mechanism of
human organ system & their mechanism
How our cells, muscles and organs work
together & how they interact
5. • 200 different specialized cells carry out a
multitude of functions
• Each system contribute to the homeostasis
of the entire body
• Cell is the structural and functional unit of
living body
• Cell Biology
• The study of cellular structure and function
6. Cell
• The basic structural, functional, and
biological unit
• Cells are the smallest unit of life that can
replicate independently
• Often called the "building blocks of life"
7. Parts Of Cell
• Most cells have many structures
• For ease of study we divide the cell into
three main parts
• Plasma membrane
• Cytoplasm
• Nucleus
Plasma Membrane
8. • Forms the flexible outer surface
• Surrounds and contains the
cytoplasm
• Separating internal from the
external environment
• It is a selective barrier
• Best described by fluid mosaic
model
Plasma membrane
9. • Molecular arrangement of the plasma
membrane resembles an ever-moving
sea of fluid lipids
• Contains a mosaic of many different
proteins
• Some proteins float freely
• Others anchored at specific locations
• Membrane lipids allow passage of
several types of lipid-soluble molecules
According to Fluid Mosaic Model
10. • Barrier to the entry or exit of charged
or polar substances
• Some proteins allow movement of
polar molecules and ions
• Other proteins can act as signal
receptors or adhesion molecules
11. Plasma Membrane Structure
• Basic structural of plasma membrane
• Lipid
• Protein
• Three types of lipid molecules
• Phospholipids
• Cholesterol
• Glycolipids
12. • Phospholipids
• 75% lipids are phospholipids lipids
• Consist of two long, nonpolar hydrocarbon
chains
• Linked to a hydrophilic head group
• Heads of phospholipids are phosphorylated
• Consist of either:
• Glycerol
• Sphingosine
• Sphingomyelin and ceramide
Lipid of Plasma Membrane
14. • Various glycolipids (about 5%), lipids with
attached carbohydrate
• Identity marker
• Cell attachment
Glycolipids
15. Cholesterol
• Present between the phospholipid
molecules
• Phospholipids are soft and oily structures
• Cholesterol helps to ‘pack’ phospholipids
• Responsible for the structural integrity
16. • The bilayer arrangement occurs because
the lipids are amphipathic molecules
• In phospholipids the polar part is the
phosphate containing “head,” which is
hydrophilic
• The nonpolar parts are the two long
fatty acid “tails,”
17. • The hydrophilic heads of phospholipid
molecules facing outward
• The heads face a watery fluid on
either side
• Cytosol on inside and extracellular
fluid on outside
• The hydrophobic fatty acid tails facing
one another
18. Membrane Proteins
• Constitute approximately 50% of the
plasma membrane composition
• Integral proteins
• Firmly embedded in the membrane
• Dissolved in the lipid bilayer
• Span the entire thickness of membrane
• Extend into the lipid bilayer among the
fatty acid tails
• Mostly they are transmembrane proteins
19. • Mostly these are glycoproteins
• Amphipathic in nature
• Have both hydrophilic and hydrophobic
amino acids
• Folded pass back and forth
• Few tightly attached to one side of the
bilayer by covalent bonding to fatty acids
20. • Function as
• Membrane receptors
• Enzymes
• Cell adhesion molecules
• Cell recognition proteins
• Function in message transduction
• Transport proteins
21. Peripheral proteins
• Not extend into the lipid bilayer
• Located on the cytoplasmic aspect of the
inner leaflet
• Outer leaflets of some cells possess
covalently linked glycolipids to which
peripheral proteins are anchored
• Thus project into the extracellular space
• Bind to the phospholipid polar groups
or integral proteins via noncovalent
interactions
22. • Associate loosely with polar heads of lipids
• Or with integral proteins
• Carbohydrate portions form sugary coat
• Glycocalyx is hydrophilic in nature
• Makes red blood cells slippery
• Molecular “signature”
• Enables cells to recognize one another
23. Function of Glycocalyx
• Aids in attachment of some cells
• Binds antigens and enzymes to the cell surface
• Facilitates cell-cell recognition and interaction
• Protects cells from injury
• Assists T-cells and antigen-presenting cells in
aligning
• In blood vessels it lines the endothelial surface
• Decrease frictional
24. Functions of Membrane Proteins
• Some integral proteins form ion channels
• Other act as carriers selectively moving a polar substance
• Carriers are also known as transporters
• Integral proteins called receptors serve as cellular recognition
sites
• Each type of receptor recognizes and binds a specific type of
molecule
• For instance, insulin receptors bind the hormone insulin
• A specific molecule that binds to a receptor is called a ligand of
that receptor
25. • Some integral proteins are enzymes that catalyze specific
• Some serve as linkers, which anchor proteins
• Membrane glycoproteins and glycolipids often serve as cell
identity markers
• The ABO blood type markers are one example of identity
markers
26. Membrane Permeability
• The permeability of the plasma membrane
varies
• Permit some substances to pass more readily
than others
• This property is termed selective
permeability
• Permeable to nonpolar, uncharged
molecules, such as oxygen, carbon dioxide,
and steroids,
• Impermeable to ions and large, uncharged
polar molecules such as glucose
• It is also slightly permeable to small,
uncharged polar molecules such as water
and urea
