dmlt syllabus physiology CELLPHYSIOLOGY.pptx

cell physiology - physiology

1. CELL PHYSIOLOGY

2. A Typical cell Cell membrane Cell organelles Membrane transport : diffusion , osmosis , active and passive transport, Endocytosis , exocytosis , Phagocytosis

3. Cell physiology Cell is basic structural and functional unit of the body.

4. Fick ’s law Fick's law states that the rate of diffusion of a substance across unit area (such as a surface or membrane) is proportional to the concentration gradient . Rate of diffusion ∝ surface area × concentration difference thickness of membrane .  ∝ means  'is proportional to'.

5. SOLVENT DRAG Solvent drag , also known as  bulk transport , refers to  solutes  in the  ultrafiltrate  that are transported back from the  renal tubule  by the flow of water rather than specifically by  ion pumps  or other  membrane transport proteins . [1]  This is a phenomenon primarily in  renal physiology , but it also occurs in gastrointestinal physiology. It generally occurs in the  paracellular , rather than  transcellular , pathway between the  tubular cells . It is seen e.g. in the passive transport in  renal sodium reabsorption ,  renal chloride reabsorption  as well as  renal urea handling .

6. SYMPORT The transport of two different molecules or ions in the same direction through a membrane using a common carrier mechanism .

7. HOMEOSTASIS Homeostasis  is the tendency to resist change in order to maintain a stable, relatively constant internal environment.

8. POSITIVE FEEDBACK MECHANISM In a  positive feedback loop feedback serves to intensify a response until an endpoint is reached. Examples of processes controlled by positive feedback in the human body include  blood  clotting and childbirth. Blood Clotting When a wound causes bleeding, the body responds with a  positive feedback loop to clot the  blood  and stop  blood  loss. Substances released by the injured blood vessel  wall begin the process of  blood  clotting. Platelets in the  blood  start to cling to the injured site and release chemicals that attract additional platelets. As the platelets continue to amass, more of the chemicals are released and more platelets are attracted to the site of the clot. The positive feedback accelerates the process of clotting until the clot is large enough to stop the bleeding.