Biophysics Introduction to biophysics Course Plan Course Contents Diffusion Osmosis

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 marks Sessionals: 30-35 marks Terminal: 50 marks

Course Contents Introduction to biophysics Forces governing biological processes Energetics and dynamics of biological systems Biomechanics fluid flow, blood circulation, muscle contraction, lever system of the body etc Membrane physics

Course Contents Electrical properties of cells Nerve Signals, nerve impulses, cardiac cycle and electrocardiography (ECG) Physics of five senses sense of sight, hearing, taste, touch and smell Physical factors of the environment Temperature, pressure, mechanical oscillations (vibrations, sound, hearing), electromagnetic fields in the environment

Books & Good Websites http://www.physicsclassroom.com/ http://highered.mcgraw-hill.com/sites/0072495855/student_view0/ Books: Human Physiology: From Cells to Systems By Lauralee Sherwood Fundamentals of Human Physiology By Lauralee Sherwood

Good Books Biophysics An Introduction to Med. Biophysics by Prakash Books Available at CAMP, NUST Advanced Biophysics by S. K. Agarwal Basic 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 Diffusion Osmosis Surface Tension Viscosity

Membrane Transport There are two types of transport mechanisms occurring in cells Active transport Passive transport We will focus mainly on passive mode of transport

Passive transport Molecules 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 Diffusion: down the concentration/chemical gradient Conduction along an electric gradient

Diffusion Molecules are in continuous random motion (Brownian motion) Evident mostly in liquids and gases whose molecules are free to move Greater 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 stream Transport of oxygen into cells of organs and to drive carbon dioxide out of them e.g lungs, eyes

Importance of diffusion in eye The 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 lungs Exchange 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 drugs Diffusion 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

Osmosis The 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

wilting Turgid plant The cells have taken up water by osmosis; the cells are turgid and the tissue is firm These cells are short of water; the tissue is limp and the plant is wilting

Growth in a shoot tip cell division continues these cells will divide 25 Growth in a shoot tip cell division continues these cells will divide vacuoles forming cells absorb water by osmosis and expand The osmotic forces generated by the cells and tissues are very large. This why you get weeds pushing up through tarmac.

Effect of different solutions on blood cells