Cytoskeleton-Intercellular-Junctions Youtube Lecture Handouts

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Image of Cytoskeleton Logo

Image of Cytoskeleton Logo

Image of Cytoskeleton Logo

Image of Cytoskeleton-Intercellular-Junctions

Image of Cytoskeleton-Intercellular-Junctions

Image of Cytoskeleton-Intercellular-Junctions

Cytoskeleton

For:

  • Structural Strength

  • Motility &

  • Cell Division

Includes

  • Microtubules

  • Intermediate filaments

  • Microfilaments

Image of Cytoskeleton

Image of Cytoskeleton

Image of Cytoskeleton

Microtubules

  • Tubular, lumen dia 15 to 20 nm.

  • Made of α tubulin & β tubulin. They form stacks of rings containing 13 subunits

Functions

  • Form spindles which move the chromosomes

  • Cell movement

  • Transport secretary granules, vesicles & mitochondria

  • Involved in the formation of Cilia & flagella

APPLIED

1. Anticancer drugs bind to microtubules & make them stable so that Mitosis stops & eventually cells die

2. Colchicine inhibits mitosis by interfering with structure of mitotic spindle (acts during metaphase) used in labs. For various studies

Intermediate filament

  • Filamentous ~10nm

  • Functions: Stable & give structural strength to cell

  • Connect nuclear memb. To cell membrane.

  • Form neurofilament in neurons & maintain axonal diameter

  • Formation of cellular junction

Microfilaments

  • Solid filaments dia. 6 to 8nm

  • Made of contractile proteins actin & myosin

  • Extension of micro filaments with plasma memb. form microvilli & they increase surface area for absorption

  • In muscle they make contractile protein

    Image of Microfilaments

    Image of Microfilaments

    Image of Microfilaments

    Image of Microtubules, Intermediate Filaments And Microfilaments

    Microtubules, Intermediate Filaments & Microfilaments

    Image of Microtubules, Intermediate Filaments And Microfilaments

Actin Filament

Image of Actin Filament

Image of Actin Filament

Image of Actin Filament

Intercellular Junction Logo

Intercellular Junction Logo

Intercellular Junction Logo

Image of Intercellular Junction

Image of Intercellular Junction

Image of Intercellular Junction

Intercellular Junctions

Types of intercellular junctions

  • Tight junctions

  • Zona Adherens

  • 3 Desmosomes / Hemi desmosomes

  • 4 Gap junctions; permits transfer of sub. Between two cells

Image of Types of Intercellular Junctions

Image of Types of Intercellular Junctions

Image of Types of Intercellular Junctions

Tight Junction

  • Also called zona occludens

  • Adjacent cell membranes are fused & there is no space between two cells

Function- they prevent movement of ions from one side of membrane to another side

Memb. Proteins cannot float

Examples

  • Apical region of epithelial cells of intestinal mucosa

  • Apical region of renal tubular cells

  • Capillary endothelium forming blood brain barrier

  • In choroid plexus

Adherens Jun. /Zona Adherens

  • Immediately below the tight junction

  • Form a band

  • Adjacent membranes are separated by 15 to 20nm gap

  • Permit water & ions

Desmosome

  • Not band but patchy

  • Cleft of 20 nm. between cells

  • Dense accumulation of proteins at focal places

  • Bundles of Intermediate Filaments project from intercellular junctional area

  • They hold cells at their places

  • Two types

A. Desmosomes

  • Thickened area on both sides of memb. & cells are attached to each other

B. Hemidesmosomes

  • Thickened area on one side only.

  • Attach cell to basal lamina

Functions

  • Attach cells to basal lamina

  • Hold cells firmly together specially at the site of stretching

Gap junctions

  • Intercellular space 2 to 3 nm

  • In between the cells channels are present, lined by proteins called Connexins

  • Eg. Basal part of epithelial cells of intestinal mucosa, heart muscles

Functions- Permit movement of amino acids, glucose, ions up to mol. weight of 1000

Rapid propogation of electric potentials from cell to cell important in Smooth & Cardiac Muscles

CAMS

  • Cells are attached to each other and to basal lamina by CAMs (cell adhesion molecules)

  • CAMs are

  • Integrins

  • Cadherins

  • Selectins

  • Adhesion mol. of IgG family

Functions of CAMs

  • Hold tissues together

  • Imp. In inflammation & tissue healing

  • Embryonic development

  • Formation of nervous system

  • Metastasis of tumors

  • Rate of apoptosis is high if CAMs are abnormal

Intercellular communication

Types

1. Neural: by neurotransmitters released at synapses

2. Endocrinal: by hormones ;which reach cells via blood

3. Paracrine communication: chemical substance secreted by a cell reach to nearby cell by diffusion in ECF. eg. In pancreas

Image of Intercellular communication

Image of Intercellular Communication

Image of Intercellular communication

Image of Intercellular communication For Paracrine Control

Image of Intercellular Communication for Paracrine Control

Image of Intercellular communication For Paracrine Control

Apoptosis

  • It is programmed cell death and is genetically controlled

  • It is caused by enzymes Capases

Nucleus

  • Present in all eukaryotic cells.

  • Controls cellular activities.

  • Essential for cell reproduction

Transport through cell membrane

Can be...

  • Passive transport

  • Active transport

  • Vesicular transport

Passive Transport: sub. Move in the direction of gradient (electrochemical)

  • Concentration gradient

  • Electric gradient

Energy is not required

Can be …

  • Diffusion

  • Simple diffusion: sub. move in the direction of gradient through semi permeable membrane

  • Facilitated diffusion: Gradient is required but a carrier is needed eg. Glucose transport

Image of Diffusion

Image of Simple Diffusion

Image of Diffusion

Simple diffusion G. Donnan Equilibrium

Image of Facilitated Diffusion

Image of Facilitated Diffusion

Image of Facilitated Diffusion

Conclusion:

1. Product of diffusible ions is same in all compartments

2. All compartments are electrically neutral

3. Total number of ions is more in C (intracellular compartment)

Image of Facilited Diffusion of Glucose

Image of Facilited Diffusion of Glucose

Image of Facilited Diffusion of Glucose

Osmosis

  • Is movement of solvent (water) from it’s high concentration (dilute solution) to low concentration. (concentrated solution)

Image of Osmosis

Image of Osmosis

Image of Osmosis

Active transport

  • Primary active transport: energy is required eg. Na+ K+ Pump

  • Secondary active transport: eg. Transport of Glucose

Image of Active transport

Image of Active Transport

Image of Active transport

Image of Outside And Inside Active Transport

Image of Outside and Inside Active Transport

Image of Outside And Inside Active Transport

Alpha subunit- Various binding

Sites

Image of Alpha subunit- Various binding

Image of Alpha Subunit- Various Binding

Image of Alpha subunit- Various binding

Image of Lumen And Blood

Image of Lumen and Blood

Image of Lumen And Blood

Image of Digoxin Mechanism of Action

Image of Digoxin Mechanism of Action

Image of Digoxin Mechanism of Action

Vesicular Transport

  • Endocytosis

  • Exocytosis

  • Transcytosis