CELL PHYSIOLOGY

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THE CELL
PHYSIOLOGY
DR.NILESH KATE.
M.D.
ASSOCIATE PROFESSOR,
DEPARTMENT OF PHYSIOLOGY,

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Objectives
 Cell structure
 Cell membrane
 Intercellular cell
junctions

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The Cell
 Basic unit
 75 to 100 trillion cells
 Coined by the British
scientist Robert Hooke
(1635 – 1703)
 ‘Cell’ – L. cella – a store
room or chamber
 Great diversity of
function

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History
 1626 – Redi – living things do not arise from
spontaneous generation
 1655 -- Robert Hooke
 1674 – Leeuwenhoek discovered protozoa. Saw
bacteria 9 yrs later
 1833 – brown – cell nucleus in cells of orchid
 1838 – Schleiden & Schwann – cell theory
 1859 – Virchow – new cells come from preexisting
cells

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Cell structure
Cell Constituents
Protoplasm.
Cytoplasm -- Cell Organelles
Inclusion bodies
Cytoskeleton
Nucleus.
Plasma membrane.

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Cell Organelles
 Definition: An
Organelle is defined
as a sub cellular
entity that is
membrane limited
and can be isolated
by centrifugation at
higher speeds.

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Principal Organelles Of The Cell
 Cell-membrane (including Nuclear-membrane)
 Mitochondria
 Endoplasmic reticulum
 Golgi apparatus
 Ribosomes
 Lysosomes
 Centrosome.
 Nucleus

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Mitochondria
Structure
Membranes
Matrix
Function

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Endoplasmic reticulum
George Pallede (1974)
Rough –
Russell’s bodies of
plasma cells
Nissl granules of nerve
cells
Acinar cells of pancreas
Smooth –
Ledig cells & adrenal
cortex

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Golgi apparatus
Camella Golgi (1898)
Functions –
Except -- Erythrocytes

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Ribosomes

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Ribosomes

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Lysosomes

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Lysosomes --Types

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Peroxisome
Catalase
oxidase

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Centrosome
Movement of
chromosomes
during cell division

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Inclusion bodies
 Lipid droplets
 Glycogen
 Proteins as secretory granules
 Melanin pigment
 Lipofuscin

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Cytoskeleton
 Microtubules
 Intermediate filaments
 Microfilaments

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Cytoskeleton (cont..)

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Molecular motors
 Microtubules based
Kinesin
Dyneins –
Cytoplasmic
Axonemal
 Actin based
myosin I
myosin II

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Nucleus
 Nuclear membrane
 Nucleoplasm --
chromosomes
 Nucleolus

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Cell membrane
 Hypothesis for cell membrane structure
The fluid mosaic model of membrane
structure – Singer & Nicolson 1972
 Arrangement of different molecules in cell
membrane.
Lipid Bilayer
Functional significance

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Cell membrane (cont..)
 Arrangement of proteins in the cell
membrane
 Peripheral proteins
Intrinsic
Extrinsic
 Integral proteins or
Transmembrane proteins
Channel proteins
Carrier proteins
Receptor proteins
Antigens
Pumps

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Cell membrane (cont..)
 Arrangement of carbohydrate in the cell
membrane
 Function.

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Intercellular junctions
 Cell adhesion molecules
 Types
 Cadherins
 Adhesion molecules of IgG subfamily
 Selectins
 Integrins

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Mechanism of adhesion
 Homophilic binding
 Heterophilic binding
 Anchorage with cytoskeleton
 Binding to laminins

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Functions of cell adhesion molecules
 Signal
 Nervous system
 Tissue holding
 Inflammation & wound healing
 Metastasis of tumour

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Types of intercellular junctions
 Tight junctions
 Adherens junctions
 Gap junctions

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THANK YOU