cell physiology

Friday, February 20, 2015

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 reticulumGeorge Pallede (1974)Rough – Russell’s bodies of plasma cellsNissl granules of nerve cellsAcinar cells of pancreasSmooth – 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

Catalaseoxidase

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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

IntrinsicExtrinsic

Integral proteins or Transmembrane proteins

Channel proteinsCarrier proteinsReceptor proteinsAntigensPumps

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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