NURS 534 Advanced Physiology 46 CORRECTLY ANSWERED QUESTIONS LATEST UPDATE

NURS 534 Advanced Physiology 46 CORRECTLY ANSWERED QUESTIONS LATEST UPDATE Most processing of ribonucleic acid (RNA) occurs in the ______ Nucleus = contains DNA and RNA, replicates, repairs, and transcribes genetic material The RNA-protein complex exist in in the cytosol in either free form or attached to the _______ The _______ is a network of channels that extend through the cytoplasm. A _____ Endoplasmic reticulum (ER) is prominent in cells that produce/secrete high qualities of proteins. important in excreting molecules (toxins); also the smooth ER is the site for synthesizing lipids and fats • Ribosomes are also located throughout the cytoplasm (i.e., they do not have to be connected with the ER). • The purpose of these structures is to translate messenger ribonucleic acid (mRNA) for proteins needed in the cytosol. For proteins that will be secreted from the cell or incorporated into the cell's membrane, then the manufacturing takes place in the ribosomes attached to the ER. Which ribosomes is this one? Free ribosomes in the cytoplasm AND Ribosomes embedded in the rough endoplasmic reticulum (ER) * A network of membranes and vesicles. * The Golgi apparatus packages proteins into vesicles * The vesicles break off from the Golgi complex and migrate to a variety of intracellular and extracellular destinations. * The Golgi complex is more prominent in some cells, particularly those that secrete proteins. (ex. immunoglobulins) Golgi complex = packaging center/transport facility • contain hydrolytic enzymes; these enzymes were synthesized in the endoplasmic reticulum (the enzymes were subsequently released from the Golgi apparatus). • These enzymes are important for hydrolyzing carbohydrates, lipids, proteins, and nucleic acids. • Enzymes in the lysosomes are tagged with a mannose‐6‐phosphate molecule. use hydrolysis (breaking hydrogen bonds) to break down excess/worn out cells • These membrane enclosed organelles contain oxidative enzymes. • Catabolism of long chain fatty acids (through β‐oxidation). These the converted to medium chain fatty acids, which are broken down to carbon dioxide and water in the mitochondria. • _______ are also important in the formation of the phospholipid, plasmalogen (plasmalogen is a component of myelin) Peroxisomes = catabolism of long chain fatty acids (through β‐oxidation) Catabolism = uses energy to break things down This organelle generates the majority of the cellular supply of adenosine triphosphate (ATP). • The _____ has a double membrane; during oxidative phosphorylation, electrons are transferred to electron donors and acceptors (e.g., oxygen). These reactions release energy (ATP). • The __________ has an independent genome, and mutations in mitochondrial genes have been associated with a variety of human diseases Mitochondria = powerhouse of the cell, site of oxidative phosphorylation Kreb Cycle creates ATP, occurs in mitochondria Glycolysis also creates ATP, occurs in cytoplasm Mitochondria has shared genetic information with prokaryotes The mitochondrion has an independent genome, and mutations in mitochondrial genes have been associated with a variety of human diseases Predominantly passed on maternally • Actin filaments (i.e., microfilaments) - components of the contractile apparatus • Intermediate filaments (e.g., keratin filaments, neurofilaments) • Microtubules - important for intracellular transport, support the movement of chromosomes during mitosis, and allow the movement of cilia and flagella. 2. Describe the extracellular matrix (ECM) in terms of structure and function • Collagen is an important protein of the ECM; collagen is synthesized by fibroblasts. • Cell adhesion molecules (CAMs): integrins, cadherins, and selectins • Elastin: an elastic protein in connective tissue that allows tissues to maintain shape during contractions/ stretching. • Fibronectin: a glycoprotein that binds to receptors on the membrane (integrins) and to collagen; important in cell adhesion and growth differentiation. Slide #6 What are the Physical connections among cells? •_____ Two adjacent cells are attached and linked by cell adhesion proteins; this fibrous connect permits stretch (e.g., skin, smooth muscle). • ______ Two cells are closely associated because their membranes join together (but it impedes the passages of molecules between the cells). • ______ the cytoplasm of two cells are directly connected; ions (and electrical impulses) pass between the cells. • ______ occur with "passive" electrical activity (movement of sodium (Na+), potassium (K+), chloride (Cl‐ ) across the plasma membrane). • ________ result in small, transient changes in membrane potential. • _______vary in terms of their strength and duration, and the signal will not travel very far (the graded potential degrades over time and space). Later (Weeks 5 and 6) we will contrast this with action potentials. • Action potential represent greater changes in the electrical properties of the membrane, and these signals travel a much longer distance. Slide#7 • The membrane is comprised of cholesterol, phospholipids, and proteins. The lipids repel the entry of water and water‐soluble molecules. • There are profound differences between the intracellular and extracellular ion concentrations. • The intracellular structures are also enclosed in membranes (e.g., mitochondria, lysosome). • The membrane also contains aquaporins,which are specialized water channels. Slide 14 • Exerts a "fluidizing" effect on the membrane. • Serves as a molecular "organizing" force. • A precursor for cell signaling cascades (e.g., phosphatidy [4,5] biphosphate, PIP2). slide 15 • Pores / channels • Carriers (actively transport substances across the membrane) • Enzymes (Na+/K+ ‐ATPase, aminopepidases) • Cell adhesion molecules (CAMs): integrins (located on the outside of the cell membrane), or cadherins (which span the membrane). • Receptors • Concentration differences between the intracellular and extracellular compartments • Molecular weight • Solubility • Electrical properties (charge) • Because cells contain aquaporin channels,water can rapidly equilibrate across the cell membrane. • The movement of water into and out of the cells is governed mainly by osmotic gradients (i.e., the differences in osmolality across the membrane), and under physiologic conditions, osmolality is similar inside and outside of the cell. So there should not be large changes in water movement between cells and among fluid compartments. • Water transport: Osmosis • Passive / diffusion: Spontaneous movement of particles from a higher concentration to a lower concentration and with the electrochemical gradient. • Facilitated transport: Requires a membrane protein. • Active transport: Requires energy to move substances against their concentration gradients. • A measure of the osmotic pressure gradient determined by the water potential between two solutions. • The two solutions are separated by a semipermeable membrane. • Determines the direction of diffusion. • The solutes that can't cross the membrane influence the tonicity. The solutes that can freely cross the membrane don't influence tonicity because they will equilibrate to have equal concentrations on either side of the membrane. What is the intracellular fluid for hypertonic solution What is the intracellular fluid isotonic solution ? What is the intracellular fluid hypotonic solution ? • Negatively‐charged proteins in the plasma, such as albumin, exert oncotic/colloid osmotic pressure. • Water filtration and absorption depend on the balance between osmotic pressure and hydrostatic pressure. • Hydrostatic pressure is an important driving force, but this is off set by the oncotic/osmotic pressure within the intravascular compartment. Rate of diffusion = concentration gradient + surface area + diffusion coefficient / membrane thickness diffusion coefficient = permeability / molecular weight • Requires an integral carrier protein (in the membrane). • The rate of transport is faster compared with simple diffusion. • But there is a maximal rate of transport (i.e., saturation). • Example: glucose transporters (e.g., GLUT1, GLUT2). These are insulin‐independent transporters. • Molecules move "up" a concentration gradient; they move against an electrochemical gradient, and this requires metabolic energy. • Typically, the movement of ions is coupled to the hydrolysis of adenosine triphosphate (ATP). • There are two classification: (1) primary active transport (the movement of ions is directly coupled with the hydrolysis of ATP), and (2) secondary active transport (the movement is coupled with the transport of another molecule [co‐transport or counter transport]). • An ion‐transporting enzyme in the plasma membrane. • This solute pump is important for sodium (Na+) and potassium (K+) movement (active transport). • Both ions are moving against their concentration gradients (i.e., Na+moving out of the cell and K+moving into the cell), which requires energy.