Brief note on Cell - signalling, Communication, Junctions.

2. Presented by
Rushendran. R
Assistant Professor
Cell Signalling

3. Cell-cell signaling involves the transmission of a signal from a sending cell to a
receiving cell. However, not all sending and receiving cells are next-door .
Signal reaches a cell phone to facilitate communication in essentially the same
manner that two-way radios communicate via a signal transmitter and
a signal receiver. When you're talking on a cell phone, it converts your voice into
a signal that is transmitted via radio waves to the nearest cell tower.

4. Why is cell Signalling
important
Cell Signaling is an important facet of biological life. It allows cells to perceive and
respond to the extracellular environment allowing development, growth, immunity, etc.
Additionally, errors in cell signaling may result in cancer growth, diabetes.

5. Cell signaling is the
fundamental process by
which specific
information is
transferred from
the cell surface to the
cytosol and ultimately
to the nucleus, leading
to changes in gene
expression.

8. Steps of Cell Signalling

9. Cell Signalling
Immune
Response
T-Cell
receptorTNF
Protein
Kinase B
Interferon
Inflammator
y
Response
MAPK
Hormone
Or
NT

10. Types of cell signalling
 Direct signalling
 Paracrine
signalling
 Autocrine
signalling
 Endocrine
signalling

11. Endocrine Signalling
The signaling molecule
s (hormones) are
secreted by
specialized endocrine c
ells and carried through
the circulation to act on
target cells at distant
body sites.
Eg: Hormones

12. Insulin is a hormone produced by the β cells in the
pancreas and is secreted into the bloodstream, from
where it can act on many different cells, even those
located far from the pancreas.

14. Example

15. Paracrine signaling is a form of cell signaling or cell-to-cell
communication in which a cell produces a signal to induce changes in
nearby cells, altering the behaviour of those cells.
Paracrine Signalling
Paracrine signals is
the chemical
transmitted from
nerve to muscle that
causes the muscle
to contract.

16. Neuron
Signalling
Ach, NA, Adrenaline, Dopamine etc.

18. Thank You

19. CELL JUNCTION
Cell junctions are a class of cellular structures consisting of multiprotein
complexes that provide contact or adhesion between neighboring cells or
between a cell and the extracellular matrix in animals. They also maintain
the paracellular barrier of epithelia and control paracellular transport

20. Tight Junction
Tight junctions, also known
as occluding junctions or
zonulae occludentes
(singular, zonula occludens)
are multiprotein junctional
complexes whose general
function is to prevent
leakage of transported
solutes and water and seals
the paracellular pathway

21. Tight junctions are often found at epithelial cells, which
are cells that line the surface of the body and line body
cavities
Tight junctions form the continuous intercellular barrier
between epithelial cells, which is required to separate
tissue spaces and regulate selective movement of
solutes across the epithelium
Functions

22. Gap junctions are a specialized intercellular
connection between a multitude of animal cell-types.
They directly connect the cytoplasm of two cells,
which allows various molecules, ions and electrical
impulses to directly pass through a regulated gate
between cells.

23. Gap junctions are found in many places throughout
the body. This includes epithelia, which are the
coverings of body surfaces, as well as nerves,
cardiac (heart) muscle, and smooth muscle (such as
that of the intestines).
Their primary role is to coordinate the activity of
adjacent cells.

24. Adherens junctions are protein complexes that
occur at cell–cell junctions in epithelial and endothelial
tissues, usually more basal than tight junctions. An
adherens junction is defined as a cell junction whose
cytoplasmic face is linked to the actin cytoskeleton.
The Adherens junction
performs multiple
functions including
initiation and
stabilization of cell-cell
adhesion, regulation of
the actin cytoskeleton,
intracellular signaling
and transcriptional
regulation.

25. Desmosomes are intercellular junctions that provide
strong adhesion between cells. Because they also link
intracellularly to the intermediate filament cytoskeleton
they form the adhesive bonds in a network that gives
mechanical strength to tissues.

26. Hemidesmosomes are very small stud-like structures
found in keratinocytes of the epidermis of skin that
attach to the extracellular matrix.
Hemidesmosomes are
found in epithelial cells
connecting the basal
epithelial cells to the
lamina lucida, which is
part of the basal
lamina
Intermediate filaments

27. Thank YouHave a nice time…