This document summarizes a lecture on cell physiology given by Dr. Nilesh Kate on February 20, 2015. The lecture covers cell structure, including the cell membrane, organelles like mitochondria and the endoplasmic reticulum, and intercellular junctions. It describes the basic components and functions of cells, provides a brief history of cell discovery, and discusses various cellular structures like organelles, the cytoskeleton, the nucleus, and the plasma membrane in detail.

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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