Complete summary of the book Human physiology, an integrated approach.

CONTENT BOOK CHAPTER 3: The cellular basis of life The plasma membrane: Structure The plasma membrane: Membrane transport The plasma membrane: Generation of membrane potential The plasma membrane: Cell-Environment interactions The cytoplasm The nucleus BOOK CHAPER 11: Membrane potential LEARNING GOALS List the three major regions of a generalized cell and their functions .......................................................................... 2 Describe the chemical composition of the plasma membrane and relate it to membrane functions .......................... 2 Relate plasma membrane structure to active and passive transport processes ........................................................... 3 Compare and contrast simple diffusion, facilitated diffusion, and osmosis relative to substances transported, direction, and mechanism ............................................................................................................................................. 3 Differentiate between primary and secondary active transport ................................................................................... 4 Compare and contrast endocytosis and exocytosis in terms of function and direction ............................................... 5 Compare and contrast pinocytosis, phagocytosis, and receptor-mediated endocytosis .............................................. 5 Define membrane potential and explain how the resting membrane potential is established and maintained.......... 5 Describe the composition of the cytosol ....................................................................................................................... 6 Discuss the structure and function of mitochondria ..................................................................................................... 6 Discuss the structure and function of mitochondria ..................................................................................................... 6 Name and describe the structure and function of cytoskeletal elements .................................................................... 6 Outline the structure and function of the nuclear envelope, nucleolus, and chromatin .............................................. 7 Compare and contrast graded potentials and action potentials ................................................................................... 7 Explain how action potentials are generated and propagated along neurons ............................................................. 7 Define absolute and relative refractory periods ........................................................................................................... 7 Downloaded by Garvita Sharma () lOMoARcPSD| A&P_Lecture 1_Cell Physiology Last Edited: 28/11/2013 Dominique Fuchs BM1107 – Anatomy & Physiology Page 2/7 LIST THE THREE MAJOR REGIONS OF A GENERALIZED CELL AND THEIR FUNCTIONS  Plasma Membrane: the outer boundary of the cell.  Nucleus: an organelle that controls cellular activities. Typically the nucleus lies near the cell’s center.  Cytoplasm: the intracellular fluid packed with organelles, small structures that perform specific cell functions. DESCRIBE THE CHEMICAL COMPOSITION OF THE PLASMA MEMBRANE AND RELATE IT TO MEMBRANE FUNCTIONS  Membrane: the main structure of the plasma membrane consists of a lipid bilayer, with protein molecules ‘plugged into’ it to perform certain functions of the plasma membrane.  Membrane Lipids: the membrane fabric consists mainly of phospholipids, and to a lesser extent glycolipids and cholesterol, and areas called lipid rafts. Phospholipids: molecules have a hydrophilic head and a hydrophobic tail, resulting in their orientation in a ‘sandwich-like’ flexible membrane structure Glycolipids: are lipids with attached sugar groups, used in the Glycocalyx along with glycoproteins to identify the cell Cholesterol: cholesterol, while similar to phospholipids has platelike hydrocarbon rings that stabilise the membrane, reducing its fluidity. Downloaded by Garvita Sharma () lOMoARcPSD| A&P_Lecture 1_Cell Physiology Last Edited: 28/11/2013 Dominique Fuchs BM1107 – Anatomy & Physiology Page 3/7 Lipid Rafts: are dynamic assemblies of saturated phospholipids together with sphingolipids and a lot of cholesterol. They can include or exclude specific proteins and are therefore assumed to be concentrating platforms for certain receptor molecules or protein molecules needed for cell signalling.  Membrane Proteins: Proteins make up about half of the membrane mass and are responsible for most specialized membrane functions. Some can move around in the membrane while others are ‘tethered’ to intracellular structures. Integral Proteins: are firmly inserted into the lipid bilayer, some protrude from one membrane face only, but most are transmembrane proteins that facilitate transport across the cell membrane through channels or pores, or act as a carrier for specific substances. Others act as enzymes or receptors for signals such as hormones.  Peripheral Proteins: are not embedded in the lipid bilayer, they attach to the outside and are easily removed. Some are enzymes while others are motor proteins used to change cell shape during cell division or cause muscle cell contraction. Still others link cells together. RELATE PLASMA MEMBRANE STRUCTURE TO ACTIVE AND PASSIVE TRANSPORT PROCESSES  The plasma membrane structures involved with passive transport are the membrane and channel proteins, while active transport involves carrier proteins.  Passive transport: takes places because of concentration gradients between the inside of the cell and the tissue around it. This causes solutes to diffuse into, and out of the cell through gaps in the cell membrane or proteins intended for the diffusion of specific solutes.  Active Transport: is caused by carrier proteins that move solutes against the concentration gradient, therefor counteracting and balancing the passive transport. Carrier proteins only transport specific solutes, providing a way for the cell to be very selective in cases where substances cannot pass by diffusion. COMPARE AND CONTRAST SIMPLE DIFFUSION, FACILITATED DIFFUSION, AND OSMOSIS RELATIVE TO SUBSTANCES TRANSPORTED, DIRECTION, AND MECHANISM  Simple diffusion: is where solutes pass directly through the lipid bilayer, this is the case for oxygen, whose concentration is always higher in the bloodstream than in the cell, and in reverse carbon dioxide. Also fatsoluble vitamins diffuse this way.  Facilitated diffusion: allows certain molecules such as glucose, other sugars and amino acids to be transported passively even though they cannot pass through the lipid bilayer. Downloaded by Garvita Sharma () lOMoARcPSD| A&P_Lecture 1_Cell Physiology Last Edited: 28/11/2013 Dominique Fuchs BM1107 – Anatomy & Physiology Page 4/7  Carrier-mediated facilitated diffusion: certain proteins change their shape to transport specific solutes across the plasma membrane, first enveloping them then releasing them into the cell, allowing them to bypass the hydrophilic lipid bilayer.  Channel-mediated facilitated diffusion: channels are transmembrane proteins that allow certain solutes (based on channel size and charges of the amino acids lining the channel) to pass through the lipid bilayer into or out of the cell, based on concentration gradients. The channels can be either leakage channels that are always open, or gated channels that are controlled by chemical or electrical signals.  Osmosis: is the movement of solvents across the plasma membrane, also along its concentration gradients. In the case of the osmosis of water across the cell membrane the Tonicity is used to describe different concentration gradients which are relevant for the osmosis of water molecules.  Isotonic: (‘the same tonicity’) solutions have the same concentration of solutes as the inside of the cell, therefore causing no change in water concentration within the cell.  Hypertonic: solutions have a higher concentration of solutes than the inside of a cell, therefore causing water to move out of the cells which then shrink (crenate).  Hypotonic: solutions have a lower concentration of solutes than cells, causing water to move into the cell, which increases in size until they burst, or lyse. DIFFERENTIATE BETWEEN PRIMARY AND SECONDARY ACTIVE TRANSPORT  Active transport uses carrier proteins like facilitated diffusion, with the difference being that active transport moves solutes against their concentration gradient.  Primary active transport: uses the hydrolysis of ATP to provide energy for the transport of solutes, like for example the Na+ -K+ pump  Secondary active transport: The energy used in secondary active transport comes from the ionic gradients created by primary active transport. These carrier proteins always work as coupled systems, carrying more than one substance at a time.  Symport system: Is a secondary active transport system that moves both solutes into the same direction  Antiport system: Is a secondary active transport system that moves solutes in opposing directions at the same time. Downloaded by Garvita Sharma () lOMoARcPSD| A&P_Lecture 1_Cell Physiology Last Edited: 28/11/2013 Dominique Fuchs BM1107 – Anatomy & Physiology Page 5/7 COMPARE AND CONTRAST ENDOCYTOSIS AND EXOCYTOSIS IN TERMS OF FUNCTION AND DIRECTION  Endocytosis: is the Vesicular transport of solutes into the cell. The cell engulfs a particle or solution which is then moved into the cell in a protein coat (often clathrin) where it is fused with an endosome for sorting, after which it is either moved to the other side of the cell (transcytosis) to be removed via exocytosis, or combined with a lysosome for ingestion.  Exocytosis: is the vesicular transport of substances out of a cell. This is often used to release hormones, neurotransmitters, mucus or for the ejection of wastes. The substance is first enclosed in a protein-coated membranous vesicle called a secretory vesicle which then migrates to the plasma membrane, fuses with it and ruptures, spilling its contents. It fuses with the plasma membrane using v-snares that couple with t-snares on the plasma membrane. COMPARE AND CONTRAST PINOCYTOSIS, PHAGOCYTOSIS, AND RECEPTOR-MEDIATED ENDOCYTOSIS  Phinocytosis: Endocytosis where the cell engulfs a drop of extracellular fluid. No receptors are used, so the process is nonspecific.  Phagocytosis: The cell engulfs a large particle within a membrane sac called phagosome. Receptors are used to identify microorganisms