PDQ Physiology ISBN VIEW CART# D 1-55009-148-4 DESCRIPTION EDITORS I TABLE OF CONTENTS |SAMPLE CHAPTER Pub date April, 2002 Pages: 520 1. General Physiological Processes 4. Autonomic Nervous System 7. Body Fluids and Electrolytes Price: 8. Gastrointestinal Systen $26.95(US) addon 9. Endocrine System -33.95(CDN) 10. Fuel Metabolism and Nutrition 11. Reproduction and Sexual Function 12. Fertilization, Pregnancy, and Lactation 3. Mineral Metabolism. Bone and Connective Tissue
PDQ Physiology ISBN: 1-55009-148-4 Pub Date: April, 2002 Pages: 520 Editor(s): Price: Uwe Ackermann MASc, PhD $26.95 (US) $33.95 (CDN) VIEW CART DESCRIPTION | EDITORS | TABLE OF CONTENTS | SAMPLE CHAPTER 1. General Physiological Processes 2. Muscle 3. Blood 4. Autonomic Nervous System 5. Respiration 6. Cardiovascular Physiology 7. Body Fluids and Electrolytes 8. Gastrointestinal System 9. Endocrine System 10. Fuel Metabolism and Nutrition 11. Reproduction and Sexual Function 12. Fertilization, Pregnancy, and Lactation 13. Mineral Metabolism, Bone, and Connective Tissue
General physiologic Processes CELL STRUCTURE AND FUNCTION Three structural features of human cells( Figure 1-1)identify them as eukaryotic cells. They are 1. a distinct membrane surrounding a central nucleus, 2. several membrane-lined intracellular structures and organelles, and 3. a number of well-defined subcellular domains in which different nicroenvironments are maintained so that several chemical reactions can occur simultaneously and optimally because the properties of the membranes defining these domains permit precise regulation of Cytosolic Membrane Systems, Organelles, and Inclusions Nucl The nucleus is the site where that portion of the human genome that rep- resents"meaningful"deoxyribonucleic acid(DNA) is transcribed into ribonucleic acid(RNA)by olymerization. Of the transcribed RNA, the majority is heterogeneous nuclear RNA that is either destroyed or further modified by capping, polyadenylation, or splicing. A small portion is messenger RNA (mRNA), which leaves the nucleus in that form and reaches the cytosol and ribosomes to be translated into proteins The nucleus is the largest intracellular organelle. It is surrounded by the nuclear membrane and contains chromatin(densely packed DNA)and
General Physiologic Processes CELL STRUCTURE AND FUNCTION Three structural features of human cells (Figure 1–1) identify them as eukaryotic cells. They are 1. a distinct membrane surrounding a central nucleus, 2. several membrane-lined intracellular structures and organelles, and 3. a number of well-defined subcellular domains in which different microenvironments are maintained so that several chemical reactions can occur simultaneously and optimally because the properties of the membranes defining these domains permit precise regulation of regional milieus. Cytosolic Membrane Systems, Organelles, and Inclusions Nucleus The nucleus is the site where that portion of the human genome that represents “meaningful” deoxyribonucleic acid (DNA) is transcribed into ribonucleic acid (RNA) by a process of regulated polymerization. Of the transcribed RNA, the majority is heterogeneous nuclear RNA that is either destroyed or further modified by capping, polyadenylation, or splicing. A small portion is messenger RNA (mRNA), which leaves the nucleus in that form and reaches the cytosol and ribosomes to be translated into proteins. The nucleus is the largest intracellular organelle. It is surrounded by the nuclear membrane and contains chromatin (densely packed DNA) and one or two nucleoli. 1 1
PDQ PHYSIOLOGY excretory vesicles L )=c Nucleolus ∴O 1-1 Elements of a typical n is the pathway of protein synthesis destination which can be membrane, or an exocytotic vesicle. ansfers occur by successive formation, delivery, and reception of transport vesicles Nuclear membrane. This is a double layer of phospholipids. The space between the layers is contiguous with the rough endoplasmic reticulum (see Figure 1-1),and the inner and outer membranes fuse together at various points and form nuclear pores, whose diameter(30 to 100 nm) permits unhindered exchange of ions, mRNA, ribosomes, and small proteins(up to 5 kilodaltons [kDa)) Nucleolus. The nucleoli, more than one of which may be present within a nucleus, consist of ribosomal rna and are the loci of rna processing and ribosome synthesis. They are not surrounded by a membrane Chromatin. This is a specific arrangement of DNA and the protein family called histones in approximately equal proportions. Its physical rrangement is in repeating units of one DNA molecule and eight histone molecules. It exists, for much of the cell cycle, as long, loosely coiled strands but condenses at cyclic intervals into well-defined chromosomes. These are the functional subunits of chromatin
Nuclear membrane. This is a double layer of phospholipids. The space between the layers is contiguous with the rough endoplasmic reticulum (see Figure 1–1), and the inner and outer membranes fuse together at various points and form nuclear pores, whose diameter (30 to 100 nm) permits unhindered exchange of ions, mRNA, ribosomes, and small proteins (up to 5 kilodaltons [kDa]). Nucleolus. The nucleoli, more than one of which may be present within a nucleus, consist of ribosomal RNA and are the loci of RNA processing and ribosome synthesis. They are not surrounded by a membrane. Chromatin. This is a specific arrangement of DNA and the protein family called histones in approximately equal proportions. Its physical arrangement is in repeating units of one DNA molecule and eight histone molecules. It exists, for much of the cell cycle, as long, loosely coiled strands but condenses at cyclic intervals into well-defined chromosomes. These are the functional subunits of chromatin. 2 PDQ PHYSIOLOGY Golgi apparatus Rough endoplasmic reticulum Nucleolus Nucleus Mitochondrion Smooth endoplasmic reticulum Peroxisome Lysosome Lysosome Ciliae Secretory vesicles cis trans Figure 1–1 Elements of a typical human cell. Also shown is the pathway of protein synthesis from rough endoplasmic reticulum to cis-Golgi, to medial Golgi, to trans-Golgi and from there to its final destination, which can be a lysosome, the plasma membrane, or an exocytotic vesicle. These transfers occur by successive formation, delivery, and reception of transport vesicles
Chapter 1 General Physiologic Processes Endoplasmic Reticulum Endoplasmic reticulum(ER)is an interconnected system of parallel mem branes that forms a fluid-filled network of interconnected chambers. Two distinct regions are recognized rough and smooth ER. Rough endoplasmic reticulum. This area of the ER is named"rough because the outside of its membrane is studded with ribosomes protein synthesis usually begins with the N-terminal and with the ribosome unattached to the ER. The N-terminal sequence and ribosome are then bound by a specific ER membrane receptor; as amino acids are assembled on each ribosome, the growing polypeptide chain is fed into the interior of the ER for further processing. Export of synthesized proteins from the ER occurs by transport vesicles that form when a portion of the ER membrane encloses a localized volume, pinches off, and moves toward the Golgi apparatus. Ribosomes. Genetic information is stored in the nucleus, but proteins are synthesized in the cytoplasm with the help of ribosomes. Ribosomes measure approximately 20 X 30 nm. They are 65% ribosomal RNA and 35% protein and consist of two subunits(40S and 60S). They are the sites of protein assembly(translation)in accordance with the blueprint carried from nuclear DNA by mRNA(Figure 1-2). Ribosomes can be attached to the cytosolic side of the rough endoplasmic reticulum, or they can be free in the cytosol. Attached ribosomes synthesize proteins that are eventually secreted from the cell, lysosomal proteins, and cell membrane proteins Free ribosomes synthesize mitochondrial, peroxisomal, or cytoplasmic proteins(e.g, hemoglobin). When a protein molecule has been assembled the two subunits of the ribosome dissociate Smooth endoplasmic reticulum. Smooth ER synthesizes membrane pids. The amount of smooth ER varies greatly among the cells of different organs, depending on the special ER tasks required in those organs. For example, the smooth ER synthesizes steroid hormones in some cells, participates in fat metabolism in cells of the gastrointestinal(GI)tract, synthesizes and stores glycogen in cells of liver and skeletal muscles, detoxifies drugs in the cells of the liver and kidneys, and stores and releases ionized calcium(Cat*)in cells of striated muscle The longitudinal sarcoplasmic reticulum of striated muscle is smooth ER. Golgi Apparatus The Golgi apparatus is the next station for the modification of proteins and polypeptides that were synthesized in the rough ER. It is near but not attached to the nuclear membrane and consists of a system of membrane
Endoplasmic Reticulum Endoplasmic retinculum (ER) is an interconnected system of parallel membranes that forms a fluid-filled network of interconnected chambers. Two distinct regions are recognized: rough and smooth ER. Rough endoplasmic reticulum. This area of the ER is named “rough” because the outside of its membrane is studded with ribosomes. Protein synthesis usually begins with the N-terminal and with the ribosome unattached to the ER. The N-terminal sequence and ribosome are then bound by a specific ER membrane receptor; as amino acids are assembled on each ribosome, the growing polypeptide chain is fed into the interior of the ER for further processing. Export of synthesized proteins from the ER occurs by transport vesicles that form when a portion of the ER membrane encloses a localized volume, pinches off, and moves toward the Golgi apparatus. Ribosomes. Genetic information is stored in the nucleus, but proteins are synthesized in the cytoplasm with the help of ribosomes. Ribosomes measure approximately 20 30 nm. They are 65% ribosomal RNA and 35% protein and consist of two subunits (40S and 60S). They are the sites of protein assembly (translation) in accordance with the blueprint carried from nuclear DNA by mRNA (Figure 1–2). Ribosomes can be attached to the cytosolic side of the rough endoplasmic reticulum, or they can be free in the cytosol. Attached ribosomes synthesize proteins that are eventually secreted from the cell, lysosomal proteins, and cell membrane proteins. Free ribosomes synthesize mitochondrial, peroxisomal, or cytoplasmic proteins (e.g., hemoglobin). When a protein molecule has been assembled, the two subunits of the ribosome dissociate. Smooth endoplasmic reticulum. Smooth ER synthesizes membrane lipids. The amount of smooth ER varies greatly among the cells of different organs, depending on the special ER tasks required in those organs. For example, the smooth ER synthesizes steroid hormones in some cells, participates in fat metabolism in cells of the gastrointestinal (GI) tract, synthesizes and stores glycogen in cells of liver and skeletal muscles, detoxifies drugs in the cells of the liver and kidneys, and stores and releases ionized calcium (Ca++) in cells of striated muscle. The longitudinal sarcoplasmic reticulum of striated muscle is smooth ER. Golgi Apparatus The Golgi apparatus is the next station for the modification of proteins and polypeptides that were synthesized in the rough ER. It is near but not attached to the nuclear membrane and consists of a system of membraneChapter 1 General Physiologic Processes 3
PDQ PHYSIOLOGY lined cisternae. It is a polarized structure, with a cis side close to the rough ER(see Figure 1-1)and a trans side at the distal end from the rough ER The sacs lying between the cis and trans sacs are termed medial golgi. The cis-Golgi receives transport vesicles from the rough ER, and the trans-Golgi releases other vesicles to their final destination(see Figure 1-1) The Golgi apparatus is a major site of membrane formation. It is here that proteins are modified, sorted, and accumulated in distinct vesicles whose ultimate destination is the plasma membrane, lysosomes, or exocy totic storage granules. Lysosomes are membrane lined and assume a variety of shapes. Primary lysosomes have just budded off from the Golgi apparatus and tend to be herical. They are filled with enzymes that are capable of digesting pro- teins, carbohydrates, lipids, nucleic acids, and other biologic material. Their digestive function follows fusion with vesicles that have enclosed the target Peroxisomes Peroxisomes resemble lysosomes in structure(single phospholipid bilayer membrane)but differ in their point of origin(they bud off the smooth ER) and they contain mostly the peroxidases and hydrolases that are required for metabolism of free oxygen radicals or the oxidation of lipids, amino acids, ethanol, and so on. Mitochondria These are elongated structures, surrounded by two phospholipid bilayers that generally do not touch( Figure 1-3). Their number in a cell is closely corre- 一 L5 Figure 1-2 Ribosomes are the sites of protein assembly ( translation) in accordance with the print camied from nuclear DNA by mRNA. Amino acid constituents of the protein the 3'end of the mRNA. When a protein molecule has been assembled, the two subunits of
lined cisternae. It is a polarized structure, with a cis side close to the rough ER (see Figure 1–1) and a trans side at the distal end from the rough ER. The sacs lying between the cis and trans sacs are termed medial Golgi. The cis-Golgi receives transport vesicles from the rough ER, and the trans-Golgi releases other vesicles to their final destination (see Figure 1–1). The Golgi apparatus is a major site of membrane formation. It is here that proteins are modified, sorted, and accumulated in distinct vesicles whose ultimate destination is the plasma membrane, lysosomes, or exocytotic storage granules. Lysosomes Lysosomes are membrane lined and assume a variety of shapes. Primary lysosomes have just budded off from the Golgi apparatus and tend to be spherical. They are filled with enzymes that are capable of digesting proteins, carbohydrates, lipids, nucleic acids, and other biologic material. Their digestive function follows fusion with vesicles that have enclosed the target. Peroxisomes Peroxisomes resemble lysosomes in structure (single phospholipid bilayer membrane) but differ in their point of origin (they bud off the smooth ER), and they contain mostly the peroxidases and hydrolases that are required for metabolism of free oxygen radicals or the oxidation of lipids, amino acids, ethanol, and so on. Mitochondria These are elongated structures, surrounded by two phospholipid bilayers that generally do not touch (Figure 1–3). Their number in a cell is closely corre- 4 PDQ PHYSIOLOGY AA4 AA2 AA1 A G C U GC UUU A A A C A G G U C U U U AA A AA3 tRNA for AA1 is leaving AA4 + tRNA are arriving Ribosome A G C UUU U G C AAA A C G C UG U U U AAA Ribosome AA1 AA2 AA4 AA3 AA5 AA6 AA7 AA8 AA9 3' 5' 3' 5' movement of ribosome assembled and growing protein mRNA Figure 1–2 Ribosomes are the sites of protein assembly (translation) in accordance with the blueprint carried from nuclear DNA by mRNA. Amino acid constituents of the protein are selected by the appropriateness of the base coding carried by the attached transfer RNA (tRNA). After each amino acid is joined to the preceding one the ribosome advances one codon toward the 3 end of the mRNA. When a protein molecule has been assembled, the two subunits of the ribosome dissociate.