Introduction to biophysicsCourse Plan

Course ContentsDiffusionOsmosis

What is “Biophysics”Biophysics is a specialized sub area of biology

It is the science of physical principles of life itself

and of biological systems. Biophysics is an

interdisciplinary science that explains the laws

and principles of physics which govern various

biological processes. Biophysics spans all levels

of biological organization from molecular scale to

whole organism

Course Plan

Quiz/Assignments: 15-20 marksSessionals: 30-35 marksTerminal: 50 marks

Course ContentsIntroduction to biophysicsForces governing biological processesEnergetics and dynamics of biological

systemsBiomechanics

fluid flow, blood circulation, muscle fluid flow, blood circulation, muscle contraction, lever system of the body etccontraction, lever system of the body etc

Membrane physics

Course ContentsElectrical properties of cells

Nerve Signals, nerve impulses, cardiac cycle Nerve Signals, nerve impulses, cardiac cycle and electrocardiography (ECG)and electrocardiography (ECG)

Physics of five senses

sense of sight, hearing, taste, touch and sense of sight, hearing, taste, touch and smellsmell

Physical factors of the environment

Temperature, pressure, mechanical Temperature, pressure, mechanical oscillations (vibrations, sound, hearing), oscillations (vibrations, sound, hearing), electromagnetic fields in the environmentelectromagnetic fields in the environment

Books & Good Websites 1. http://www.physicsclassroom.com/2. http://highered.mcgraw-hill.com/sites/00724

95855/student_view0/

Books: Human Physiology: From Cells to

Systems By Lauralee Sherwood Fundamentals of Human Physiology By

Lauralee Sherwood

Good BooksBiophysicsAn Introduction to Med.

Biophysics  by Prakash

Books Available at CAMP, NUSTAdvanced Biophysics by S. K.

AgarwalBasic Biophysics –For

Biologist- by M.Daniel

Biological activities happening in different organs of living body like kidney, liver, heart, lungs as well as those in intracellular and extracellular biological fluid are governed by fundamental laws of physics namely

DiffusionOsmosisSurface Tension Viscosity

Membrane Transport There are two types of transport mechanisms

occurring in cells1. Active transport2. Passive transport

We will focus mainly on passive mode of transport

Passive transportMolecules that can penetrate the plasma

membrane on their own that is unassisted (without consuming cell energy) are passively driven across the membrane by two forces

1.Diffusion: down the concentration/chemical gradient

2.Conduction along an electric gradient

DiffusionMolecules are in continuous random

motion (Brownian motion)Evident mostly in liquids and gases whose

molecules are free to moveGreater the concentration of molecules

greater the likelihood of collision and movement to chamber with low concentration

Importance of diffusion

Transfer of nutrients to body cells from blood streamTransport of oxygen into cells of organs and to drive carbon dioxide out of

them e.g lungs, eyes

Importance of diffusion in eyeThe cornea is unusual in that it is transparent. The tissues

that make up the cornea are able to maintain their transparency partly by not having blood vessels flowing through them.

Without blood vessels the cornea must get it's Oxygen directly from the air. The oxygen first dissolves in the tears and then diffuses throughout the cornea to keep it healthy. Equally important, the waste product carbon dioxide diffuses out of the cornea and into the atmosphere in the reverse process

Diffusion of gases in lungsExchange of gases across the

alveolar membrane takes place due to diffusion

The blood carried to lungs is low in O2, having given up O2 to the body tissues for cellular metabolism while the air in alveolus is rich in oxygen

Because of this concentration gradient, oxygen diffuses into the blood

Similarly CO2 diffuses out of the blood into alveolus

Absorption of drugsDiffusion enables absorption of drugs across

a biological barrier (layers of cells, cell membranes etc) into the bloodstream administered through any mean except for intravenous administration

For example, transport of medicine from transdermal patch to skin and then into bloodstream occurs by passive diffusion

OsmosisThe spontaneous passage of solvent from a solution of

lower concentration towards a solution of higher concentration when the two are separated by a semi permeable membrane is called osmosis

Osmosis is a special case of diffusion. It involves the diffusion of water through the semi permeable membrane to equalise the concentration of solutions on its two sides

Osmosis in fresh and sea water fish

Fresh water trout Sea water Herring

These cells are short of water; the tissue is limp and the plant is wilting

The cells have taken up water by osmosis; the cells are turgid and the tissue is firm

wilting Turgid plant

these cells will divide

vacuolesforming

cells absorb water by osmosis and expand

cell divisioncontinues

Growth in a shoot tip

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Effect of different solutions on blood cells