Human physiology is the study of the normal functions and mechanisms of human organs and body systems, including how cells, muscles, and organs work together and interact. The cell is the basic structural and functional unit of the body. The plasma membrane forms the outer surface of the cell and acts as a selective barrier, separating the internal and external environments according to the fluid mosaic model. It consists of a bilayer of phospholipids, cholesterol, and proteins embedded within this lipid bilayer.

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

4. Cell & Homeostasis

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

13. Types of Phospholipid
• Phospholipids present in lipid layer
• Aminophospholipids
• Sphingomyelins
• Phosphatidylcholine
• Phosphatidyletholamine
• Phosphatidylglycerol
• Phosphatidylserine
• Phosphatidylinositol

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