Week 2 Physiology PDF

Name of Department : Physical Therapy and Rehabilitation (English) Course Code and Name : PHYSIOLOGY (BEY 141-E) Course Week : 2 Course Day and Time : Friday (14:00 to 17:45) ROOM 101 (Block B) InformationCourse Credit/ACTS : 3 Exa...

Name of Department : Physical Therapy and Rehabilitation (English) Course Code and Name : PHYSIOLOGY (BEY 141-E) Course Week : 2 Course Day and Time : Friday (14:00 to 17:45) ROOM 101 (Block B) InformationCourse Credit/ACTS : 3 Examination Type and Gradings : Assignments and Mcqs Instructor’s Name & Surname : Dr. Nasir Mustafa E-mail & Phone: : [email protected] Instructor’s Room : 304 Block - B Office Hours : 9:00 to 18:00 GBS Link : https://gbs.gelisim.edu.tr/en/lesson-details-5-159-11120-2 ALMS Link : https://lms.gelisim.edu.tr/almsp/u/Home/Index AVESIS Link : https://avesis.gelisim.edu.tr/nmustafa  | 14 WEEKS’S COURSE CONTENTS | 1. INTRODUCTION TO PHYSIOLOGY, CELLS, 9. HEART TISSUES, ORGANS AND SYSTEMS 10. RESPIRATORY SYSTEM 2. CELL ORGANELLES AND CELL TRANSPORT MECHANISMS 11. DIGESTIVE SYSTEM 3. DISTRIBUTION OF BODY FLUIDS, ELECTROLYTES 12. ENDOCRINE SYSTEM 4. BLOOD 13. REPRODUCTIVE SYSTEM 5. CIRCULATORY SYSTEM 14. EXCRETION SYSTEM 6. NERVOUS SYSTEM 7. MUSCULAR AND SKELETAL SYSTE 15. SYSTEMS OVERVIEW 8. MID-TERM EXAM 16. FINAL EXAM  | Course Assessment | Activities could be quizzes, assignments, presentation, report, project, ………..  | NOTE | Attendance Attendance is mandatory for all scheduled lectures.  | NOTE | Assignment Deliver the assignments before the deadline.  | NOTE | Quiz Quizzes will be held online. (No excuses)  | NOTE | Be Responsible Come to class on time.  | NOTE | Be disciplined Avoid talking to friends in the class.  | NOTE | Show discipline Mobiles are not allowed in the class.  | WEEKLY LEARNING OUTCOMES | The weekly learning outcomes for Cell Physiology and Transport Mechanisms Cell Functions: Understand basic cell functions like metabolism, growth, and reproduction. Cell Organelles: Describe the structure and roles of organelles (nucleus, mitochondria, etc.). Passive Transport: Explain diffusion, osmosis, and facilitated diffusion. Active Transport: Understand mechanisms like the sodium-potassium pump. Vesicular Transport: Learn about endocytosis and exocytosis. Homeostasis: Relate transport mechanisms to maintaining homeostasis.  | ABOUT THE PREVIOUS LESSON | Physiology: The study of how body systems, organs, tissues, and cells work together to maintain life and homeostasis. Cells: The basic units of life, consisting of membranes, nuclei, and cytoplasm, performing essential functions. Tissues: Four types—epithelial, connective, muscle, and nervous—each with specific roles. Organs: Structures made of multiple tissues that perform distinct functions (e.g., heart, lungs). Organ Systems: Groups of organs that work together (e.g., respiratory, digestive) to maintain homeostasis and overall body function.  | DAILY FLOW | 14:00-14:50/ 1st Hour 15:00-15:50/ 2nd Hour 16:00-16:50/ 3rd Hour 17:00-17:45/ 4th Hour  Depth and Breath Conceptual Depth and Practical Depth Thematic Breadth and Interdisciplinary Breadth Teaching Methods and Techniques Lectures: Traditional method where the instructor presents information to the class. Effective for delivering large amounts of content efficiently. Presentation: Interactive sessions that allow for deeper discussion, hands-on practice, and exploration of specific topics. Group Projects: Collaborative work that encourages teamwork and application of concepts in a practical context. Problem-Based Learning (PBL): Students work on complex, real-world problems, which helps develop critical thinking and problem-solving skills. Flipped Classroom: Students review lecture material at home and engage in interactive activities during class time to deepen understanding. Online Learning Modules: Use of digital platforms for delivering content, quizzes, and interactive activities that allow for flexible learning. Assessments and Feedback: Regular evaluations through quizzes, exams, and assignments, coupled with constructive feedback to guide learning progress.  LEARNING OBJECTIVES: Understand Cell Structure and Function: Describe the major components of a cell and their specific functions in maintaining cellular physiology. Explain Cell Membrane Structure: Understand the structure of the cell membrane and its role in controlling the movement of substances into and out of the cell. Differentiate Between Transport Mechanisms: Distinguish between passive transport (diffusion, osmosis, facilitated diffusion) and active transport (primary and secondary active transport). Explore Vesicular Transport: Explain the processes of endocytosis (e.g., phagocytosis, pinocytosis) and exocytosis, and their importance in cellular function. Understand the Role of Ion Channels and Pumps: Discuss the function of ion channels, the sodium- potassium pump, and their role in maintaining the cell's resting membrane potential. Relate Transport Mechanisms to Cell Physiology: Explain how different transport mechanisms contribute to the overall functioning and homeostasis of the cell. Apply Knowledge to Real-Life Examples: Use examples from physiology or medicine to illustrate how dysfunction in cell transport mechanisms can lead to disease.  Today’s Topic Cell Organelles and Transport Mechanism igugelisim gelisimedu  DEFINITION OF CELL The smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane.  CELL Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. ORGANELLES  NUCLEUS STRUCTURE Spherical with double membrane contains nucleolus, chromosome, and nuclear membrane FUNCTION Control and regulate all activities on cell Contain hereditary factor (gene) responsible for the trait  Rough and Smooth ER STRUCTURE System of membrane enclosed tubules closely packed together and continuous with nuclear membrane Rough ER has ribosome while smooth ER did not have FUNCTION Transport system for protein and lipid within the cell Rough ER transport protein synthesis by ribosome to other part of the cell Smooth ER stimulate the synthesis of lipid and cholesterol and transport within cell  RIBOSOME STRUCTURE Small particle consist of RNA Exist freely in cytoplasm or on the surface of rough ER FUNCTION Synthesis of protein  MITOCHONDRIA STRUCTURE Rod-shape with a double membrane Outer membrane is smooth and regular while inner membrane is folded to form cristae FUNCTION Known as the ‘power-house’ of the cell Releases energy as it the site for aerobic respiration  GOLGI APPARATUS STRUCTURE Vacuolar region surrounded by a complex meshwork of vesicles budding off at its end FUNCTION Receive protein and lipid from ER and modify them to form secretion enzyme /hormone Pack the secretion formed into vesicle and transport to plasma membrane Control secretory activity Form lysosome  LYSOSOMES STRUCTURE Membrane bound vesicle found in animal FUNCTION Contain enzyme which control breakdown of protein and lipid Contain enzyme that digest aged or defective cell component  CENTRIOLES STRUCTURE Consist of two cylindrical body structure arranged at right angles to one another Only in animal cell FUNCTION Formation of spindle fiber during cell division  VACUOLE STRUCTURE Cavities filled with cell fluid surrounded by a semi-permeable membrane. FUNCTION In animal cells, vacuoles perform mostly subordinate roles, assisting in larger processes of exocytosis and endocytosis.  PLASMA MEMBRANE STRUCTURE Thin, semi-permeable membrane made up of lipid bilayer FUNCTION Control the movement of substance in and out of the cell  CYTOPLASM STRUCTURE Jelly-like substance contain water and mineral salt Contain organelles FUNCTION Medium for metabolic reaction  ORGANELLES & FUNCTIONS Mitochondria: Supplies energy to the cell. Also Power house of the cell. Ribosomes: Link amino acids to form proteins. Also called Proteins factories of the cell. Endoplasmic Reticulum (ER): Produces proteins and lipids, breaks down drugs and alcohol. Lysosomes: Protect the cell from invaders, break down, and digest materials. Centriole: Helps in DNA division and forms cilia and flagella. Nucleus: Controls all activity if the cell. Stores genetic information. Golgi Apparatus: Processes, sorts, and delivers proteins. Packaging factories of the cell. Modify secretions in the form of enzyme. Vacuole: Used for storage. Cell Smallest living unit of structure and function of all organisms is the cell. Its two major parts are the nucleus and the cytoplasm. The nucleus is separated from the cytoplasm by a nuclear membrane, and the cytoplasm is separated from the surrounding fluids by a cell membrane (plasma membrane). igugelisim gelisimedu Cell igugelisim gelisimedu Cell The different substances that make up the cell are collectively called protoplasm. Protoplasm is composed mainly five basic substances: water, electrolytes, proteins, lipids carbohydrates. igugelisim gelisimedu Cell Protoplasm is composed mainly of five basic substances: 1. Water; 70-85 % of the cell. 2. Electrolytes; potassium, magnesium, phosphate, sulfate, bicarbonate, and smaller quantities of sodium, chloride, and calcium. 3. Protein; 10-20 %. Two types: a) structural proteins: long filaments (microtubules, cytoskeleton, collagen, elastin) b) functional proteins: globular (enzymes) 3. Lipids; 2%. phospholipids and cholesterol. In fat cells 95% of triglycerides. 4. Carbohydrates; 1%. nutritional and energy storage function. igugelisim gelisimedu Structure of the Cell Intracellular organelles: Membranes: Lipid: barier Protein: passage and enzyme igugelisim gelisimedu Cell Membrane (Plasma Membrane) The cell membrane is a thin, elastic structure. 7.5 to 10 nanometers thick. It is composed of proteins, lipids and carbohydrates. proteins, 55% phospholipids, 25% cholesterol, 13% other lipids, 4% carbohydrates, 3%. igugelisim gelisimedu Cell Membrane (Plasma Membrane) Its basic structure is a lipid bilayer which covers the entire cell surface. Large globular protein molecules are embedded in this lipid bilayer. igugelisim gelisimedu Cell Membrane (Plasma Membrane) The basic lipid bilayer is composed of phospholipid molecules. The phosphate end of the phospholipid is hydrophilic, and the fatty acid portion is hydrophobic. The lipid layer in the middle of the membrane is impermeable to the water-soluble substances (ions, glucose, urea). Fat-soluble substances, such as oxygen, carbon dioxide, and alcohol, can penetrate this portion of the membrane. igugelisim gelisimedu Cell Membrane (Plasma Membrane) Membrane proteins; 1. integral proteins: channel, carrier protein, enzyme, receptor 2. peripheral proteins: enzymes igugelisim gelisimedu Cell Membrane (Plasma Membrane) Membrane Carbohydrates “Glycocalyx.” Glycoproteins or glycolipids protrude to the outside of the cell The entire outside surface of the cell has a loose carbohydrate coat called the glycocalyx. Glycocalyx functions: 1) have a negative electrical charge, which repels other negative objects. 2) The glycocalyx attaches to the glycocalyx of other cells, 3) Acts as receptor for hormones, 4) Have some immune reactions. igugelisim gelisimedu Cell Organelles Cytoplasm: is the clear liquid portion inside of the cell. Cytosol: is cytoplasm plus dissolved particles and organelles inside of the cell. neutral fat globules, glycogen granules, secretory vesicles, and organelles: the endoplasmic reticulum, the Golgi apparatus, mitochondria, lysosomes, ribosomes and peroxisomes. igugelisim gelisimedu Cell Organelles Endoplasmic Reticulum: network of tubular and flat vesiculs. ER is filled with endoplasmic matrix. ER is connected with the nuclear membrane. Substances formed in some parts of the cell enter the ER and then conducted to other parts of the cell. igugelisim gelisimedu Cell Organelles Endoplasmic Reticulum: 1. Granular ER: for the synthesis of new protein molecules. 2. Agranular ER: for the synthesis of lipid substances. igugelisim gelisimedu Cell Organelles Golgi Apparatus Closely related to the ER. This apparatus is prominent in secretory cells. Substances entrapped in the ER vesicles are transported from the ER to the Golgi apparatus. The transported substances are then processed in the Golgi apparatus to form lysosomes and secretory vesicles. igugelisim gelisimedu Cell Organelles Lysosomes, are vesicular organelles that form by breaking off from the Golgi apparatus and then dispersing throughout the cytoplasm. It is surrounded by a typical lipid bilayer membrane and is filled with large numbers of small granules, which are protein aggregates of hydrolase (digestive) enzymes. igugelisim gelisimedu Cell Organelles The lysosomes provide an intracellular digestive system that allows the cell to digest ; 1) damaged cellular structures, 2) food particles that have been ingested by the cell, 3) unwanted matter such as bacteria. igugelisim gelisimedu Cell Organelles Peroxisomes are formed by self-replication or by sER. They contain oxidases. Oxidases are combining oxygen with hydrogen ions to form hydrogen peroxide (H2 O2 ). Catalase, another oxidase enzyme present in peroxisomes, to oxidize many substances that might otherwise be poisonous to the cell. igugelisim gelisimedu Cell Organelles Mitochondria: the total number depending on the amount of energy required by the cell. Mitochondria are self-replicative, contain DNA similar to that found in the cell nucleus igugelisim gelisimedu Cell Organelles Mitochondria; is composed mainly of two lipid bilayer– protein membranes. Oxidative enzymes are attached to the foldings of the inner membrane. The inner cavity of the mitochondrion is filled with a matrix that contains large quantities of dissolved enzymes that are necessary for extracting energy from nutrients. These enzymes operate in association with the oxidative enzymes to cause oxidation of the nutrients, thereby forming carbon dioxide and water and at the same time releasing energy. The liberated energy is used to synthesize a “high-energy” substance called adenosine triphosphate (ATP). igugelisim gelisimedu Cell Organelles Cell Cytoskeleton The fibrillar proteins of the cell are usually organized into filaments or tubules. Actin filaments occur in the outer zone of the cytoplasm (ectoplasm), and form an elastic support for the cell membrane. In muscle cells, actin and myosin filaments are organized for muscle contraction. A special type of filament composed of polymerized tubulin molecules is used in all cells to construct strong tubular structures, the microtubules (flagellum of a spermium). igugelisim gelisimedu Cell Organelles Nucleus: control center of the cell. The nucleus contains large quantities of DNA, which are the genes. The genes determine the characteristics of the cell’s proteins, including the structural proteins and the intracellular enzymes that control cytoplasmic and nuclear activities. The genes also control and promote reproduction of the cell. igugelisim gelisimedu Cell Organelles The nuclear membrane (nuclear envelope), is two separate bilayer membranes. The outer membrane is continuous with the ER. The nuclear membrane is penetrated by nuclear pores. The nucleolus, does not have a limiting membrane. It is an accumulation of large amounts of RNA and proteins. The nucleolus becomes enlarged when the cell is actively synthesizing proteins. igugelisim gelisimedu The relationships found by Chargaff were as follows: The amount of adenine (A) was equal to the amount of thymine (T) and the amount of guanine (G) cytosine (C)  DNA RNA Uses the information Stores genetic information stored in DNA to make for the cell proteins Contains the 5-carbon Contains the 5-carbon sugar deoxyribose sugar ribose Double-stranded Single-stranded Contains thymine Contains uracil Synthesised Self-replicating by transcription Genetic Control of Protein Synthesis and Reproduction Each gene, which is a nucleic acid called deoxyribonucleic acid (DNA), controls the formation of another nucleic acid, ribonucleic acid (RNA). RNA then spreads throughout the cell to control the formation of a specific protein. The entire process, from transcription to translation of the RNA and formation of proteins is referred to as gene expression. igugelisim gelisimedu Transcription AND Translation Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA). The newly formed mRNA copies of the gene then serve as blueprints for protein synthesis during the process of translation. Translation is the process by which a protein is synthesized from the information contained in a molecule of messenger RNA (mRNA). igugelisim gelisimedu  Genetic Control of Protein Synthesis and Reproduction igugelisim gelisimedu Genetic Control of Protein Synthesis and Reproduction Basic chemical compounds of DNA: 1) phosphoric acid, 2) a sugar called deoxyribose, 3) four nitrogenous bases two purines, adenine and guanine, two pyrimidines, thymine and cytosine). igugelisim gelisimedu Genetic Control of Protein Synthesis and Reproduction Nucleotides are bound together to form two strands of DNA. 1. Each purine base adenine of one strand always bonds with a pyrimidine base thymine of the other strand 2. Each purine base guanine always bonds with a pyrimidine base cytosine. igugelisim gelisimedu Genetic Control of Protein Synthesis and Reproduction When the two strands of a DNA molecule are split apart, this exposes the purine and pyrimidine bases projecting to the side of each DNA strand. The genetic code consists of “triplets” of bases—that is, each three bases is a code word. (RNA transcription) The triplets control the sequence of amino acids in a protein molecule. igugelisim gelisimedu Genetic Control of Protein Synthesis and Reproduction Four Different Types of RNA. 1. Messenger RNA (mRNA), carries the genetic code to the cytoplasm. 2. Transfer RNA (tRNA), transports activated amino acids to the ribosomes. 3. Ribosomal RNA, forms ribosomes. 4. MicroRNA (miRNA), single-stranded RNA molecules that can regulate gene transcription and translation. igugelisim gelisimedu Genetic Control of Protein Synthesis and Reproduction Messenger RNA travels through the ribosome, a protein molecule is formed—a process called translation. igugelisim gelisimedu Synthesis of Other Substances in the Cell Protein enzymes control all the other chemical reactions that take place in cells. These enzymes promote synthesis of lipids, glycogen, purines, pyrimidines and other substances. igugelisim gelisimedu Genetic Control In summary, there are two principal methods for reguation of cell functions; 1) the mechanism of genetic regulation, 2) the mechanism of enzyme regulation. These regulatory mechanisms most often function as feedback control systems that continually monitor the cell’s biochemical composition and make corrections as needed. igugelisim gelisimedu Genetic Control on Cell Reproduction The genes and their regulatory mechanisms determine the growth characteristics of the cells. Different cells of the body have different life cycle periods. Cell reproduction is a series of physical events called «mitosis» (the cell splits into two new cells). igugelisim gelisimedu Genetic Control on Cell Reproduction The first step of cell reproduction is replication (duplication) of all DNA in the chromosomes. Mitotic apparatus (Centriole): two pairs of centrioles lie close to each other near one pole of the nucleus. Shortly before mitosis, the two pairs of centrioles begin to move apart from each other to the each end of the cell. igugelisim gelisimedu Genetic Control on Cell Reproduction 1. Prophase: the chromosomes of the nucleus become condensed into well-defined chromosomes. 2. Prometaphase: the growing microtubular spines fragment the nuclear envelope and attach to the chromatids. 3. Metaphase: the two asters of the mitotic apparatus are pushed farther apart. Simultaneously, the chromatids are pulled tightly to the center of the cell, lining up to form the equatorial plate. 4. Anaphase: the two chromatids of each chromosome are pulled apart at the centromere. All 46 pairs of chromatids are separated, forming two separate sets of 46 daughter chromosomes. One of these sets is pulled toward one mitotic aster and the other toward the other aster. 5. Telophase: the two sets of daughter chromosomes are pushed completely apart. Then the mitotic apparatus dissolutes, and a new nuclear membrane develops around each set of chromosomes. Shortly thereafter, the cell pinches in two, midway between the two nuclei. igugelisim gelisimedu Genetic Control on Cell Reproduction Experiments have shown three cell growth control mechanisms: 1. growth factors, 2. normal cells stop growing when they have run out of space for growth, 3. cells grown in tissue culture stop growing when their own secretions are allowed to collect in the culture medium. igugelisim gelisimedu Genetic Control on Cell Reproduction Cell differentiation, refers to changes in physical and functional properties of cells. When cells are no longer needed, they undergo a programmed cell death or apoptosis. igugelisim gelisimedu Genetic Control on Cell Reproduction Cancer is caused by mutation or by some other abnormal activation of cellular genes that control cell growth and cell mitosis. The abnormal genes are called oncogenes. Also present in all cells are antioncogenes, which suppress the activation of specific oncogenes. Therefore, loss or inactivation of antioncogenes can allow activation of oncogenes that lead to cancer. Some chemical, physical, or biological factors can increase the mutation probability: ionizing radiation chemical substances physical irritants hereditary tendency viruses igugelisim gelisimedu Cellular Functions Endocytosis Very large particles enter the cell by a specialized function of the cell membrane called endocytosis. 2 types; Pinocytosis: ingestion of small particles that form vesicles of extracellular fluid and particulate constituents inside the cell cytoplasm. Phagocytosis: ingestion of large particles, such as bacteria, whole cells, or portions of degenerating tissue. igugelisim gelisimedu Cellular Functions ER Functions: Production of proteins and lipids. Provides the enzymes that control glycogen breakdown when glycogen is to be used for energy. Provides enzymes for detoxifying substances (drugs). igugelisim gelisimedu Cellular Functions Mitochondria Functions: The substances from which cells extract energy are foodstuffs that react chemically with oxygen; carbohydrates, fats, and proteins. Briefly, all oxidative reactions occur inside the mitochondria and the energy that is released is used to form the high-energy compound ATP. Then, ATP is used throughout the cell to energize all the metabolic reactions. igugelisim gelisimedu Cellular Functions ATP (Adenosine TriPhosphate) is a nucleotide composed of; 1) the nitrogenous base adenine, 2) the pentose sugar ribose, 3) three phosphate radicals. The last two phosphate radicals are connected with the high-energy phosphate bonds, (symbol ~). Each of these high energy bonds contains about 12,000 calories/mol ATP, When ATP releases its energy, adenosine diphosphate (ADP) is formed. igugelisim gelisimedu Cellular Functions ATP (Adenosine TriPhosphate) This released energy is used to energize many of the cell’s functions; synthesis of substances, transport of substances through the membranes and muscular contraction. igugelisim gelisimedu Transport of Substances Through Cell Membranes Cell membrane acts as a semi permeable boundary, allowing only certain substances (selectively permeable) to enter or leave the cell. igugelisim gelisimedu Transport of Substances Through Cell Membranes Concentrations of important electrolytes and other substances in the extracellular fluid and intracellular fluid are different. These differences are extremely important to the life of the cell. igugelisim gelisimedu igugelisim gelisimedu Transport of Substances Through Cell Membranes Cell membrane consists of; a lipid bilayer, protein molecules: channel proteins carrier proteins igugelisim gelisimedu igugelisim gelisimedu Transport of Substances Through Cell Membranes Membrane transport: movement of substances in and out of the cell. Two Types of Transport Mechanisms: Passive Transport Active Transport igugelisim gelisimedu Transport of Substances Through Cell Membranes All molecules and ions in the body fluids are in constant motion, each particle moving its own separate way. This continual movement of molecules among one another in liquids or in gases is called diffusion. igugelisim gelisimedu igugelisim gelisimedu igugelisim gelisimedu igugelisim gelisimedu Transport of Substances Through Cell Membranes Diffusion through the cell membrane is divided into two subtypes; Simple diffusion Facilitated diffusion. igugelisim gelisimedu Transport of Substances Through Cell Membranes Simple diffusion: kinetic movement of molecules or ions through a channel protein or lipid bilayer without any interaction with carrier proteins in the membrane. igugelisim gelisimedu igugelisim gelisimedu Transport of Substances Through Cell Membranes Simple diffusion can occur through the cell membrane by two pathways: 1) through the lipid bilayer if the diffusing substance is lipid soluble 2) through channels (transport proteins) igugelisim gelisimedu Transport of Substances Through Cell Membranes Example: the lipid solubilities of oxygen, nitrogen, carbon dioxide, and alcohols are high, so all these can diffuse directly through the cell membrane. The rate of diffusion of each of these substances through the membrane is directly proportional to its lipid solubility. igugelisim gelisimedu Transport of Substances Through Cell Membranes The main factors that influence the diffusion rate; Molecul size Lipid solubility Gradient Size Temperature Distance to diffuse igugelisim gelisimedu Transport of Substances Through Cell Membranes Aquaporins (water channels): protein pores, allow rapid passage of water through cell membranes but exclude other molecules. At least 13 different types of aquaporins have been found in various cells of the human body. igugelisim gelisimedu Transport of Substances Through Cell Membranes 1.Osmosis movement of water from high concentration to the low concentration igugelisim gelisimedu Transport of Substances Through Cell Membranes Osmotic concentration is determined by the the concentration of all solutes in solution Relative Osmotic Concentrations: Hypertonic solutions: have a higher relative solute concentration Hypotonic solutions: have a lower relative solute concentration Isotonic Solutions: have equal relative solute concentrations igugelisim gelisimedu igugelisim gelisimedu igugelisim gelisimedu Transport of Substances Through Cell Membranes The protein channels are distinguished by two important characteristics: 1) Selective permeability 2) Opening or closing of the channel is regulated by electrical signals (voltage-gated channels) or chemicals that bind to the channel proteins (ligand-gated channels). igugelisim gelisimedu Transport of Substances Through Cell Membranes Facilitated diffusion (carrier-mediated diffusion): requires interaction of a specific carrier protein. The carrier protein aids passage of the molecules or ions through the membrane by binding chemically with them and carrying them through the membrane. igugelisim gelisimedu igugelisim gelisimedu Transport of Substances Through Cell Membranes Difference between simple and facilitated diffusion; The rate of simple diffusion through an open channel increases proportionately with the concentration of the diffusing substance, but in facilitated diffusion the rate of diffusion approaches a maximum, called Vmax, as the concentration of the diffusing substance increases. igugelisim gelisimedu Transport of Substances Through Cell Membranes Example: glucose and most of the amino acids are crossing cell membranes by facilitated diffusion. At least five glucose transporter molecules have been discovered in human body. Glucose transporter 4 (GLUT4), is activated by insulin, which can increase the rate of facilitated diffusion of glucose as much as 10-fold to 20-fold in insulin- sensitive tissues. igugelisim gelisimedu Transport of Substances Through Cell Membranes Active transport: a cell membrane moves molecules or ions “uphill” against a concentration gradient (or “uphill” against an electrical or pressure gradient) Examples; actively transported substances (sodium, potassium, calcium, iron, hydrogen, chloride, iodide, urate, some sugars and most of the amino acids). igugelisim gelisimedu Transport of Substances Through Cell Membranes The sodium-potassium (Na+ -K+ ) pump: the cell membrane of all cells have This transport process pumps 3 sodium ions out and at the same time pumps 2 potassium ions inside of the cell. This pump is responsible for maintaining the sodium and potassium concentration differences across the cell membrane, as well as for establishing a negative electrical voltage inside the cells. This pump is also the basis of nerve function, transmitting nerve signals throughout the nervous system. igugelisim gelisimedu Transport of Substances Through Cell Membranes The sodium-potassium (Na+ -K+ ATPase) pump: igugelisim gelisimedu Transport of Substances Through Cell Membranes Other examples of primary active transport; Primary Active Transport of Calcium Ions: (sarcoplasmic reticulum of muscle cells and the mitochondria in all cells) Primary Active Transport of Hydrogen Ions (in the gastric glands of the stomach and in the kidneys). igugelisim gelisimedu Transport of Substances Through Cell Membranes When sodium ions are transported out of cells by primary active transport, a large concentration gradient of sodium ions across the cell membrane usually develops— high concentration outside the cell and low concentration inside. This gradient represents a storehouse of energy because the excess sodium outside the cell membrane is always attempting to diffuse to the interior. Under appropriate conditions, this diffusion energy of sodium can pull other substances along with the sodium through the cell membrane. This phenomenon is called co-transport; it is one form of secondary active transport. igugelisim gelisimedu Transport of Substances Through Cell Membranes Na-glucose co-transporter igugelisim gelisimedu Transport of Substances Through Cell Membranes Counter-transport: This time, when a substance is transported to the inside of the cell, at the same time, other substance must be transported to the outside. Therefore, the sodium ion binds to the carrier protein, while the substance to be counter-transported binds to the interior projection of the carrier protein. Once both have bound, a conformational change occurs, and energy released by the sodium ion moving to the interior causes the other substance to move to the exterior. igugelisim gelisimedu Transport of Substances Through Cell Membranes Figure: Counter-transport igugelisim gelisimedu Membrane Potential and Action Potential Electrical potentials exist across the membranes of all cells of the body. In addition, some cells, such as nerve and muscle cells, are capable of generating rapidly changing electrochemical impulses at their membranes, and these impulses are used to transmit signals along the nerve or muscle membranes. igugelisim gelisimedu Membrane Potential and Action Potential Membrane potential (MP) - a transmembrane potential difference that exists between the inner and outer surfaces of the plasma membrane. igugelisim gelisimedu Membrane Potential and Action Potential Membrane potential (MP) - a transmembrane potential difference that exists between the inner and outer surfaces of the plasma membrane. WHY ? Unequal distribution of ions, Cell contains negatively charged proteins and phosphate groups that can not pass through the membrane. igugelisim gelisimedu Membrane Potential and Action Potential Ion ECF ICF Na+ 145 mM 12 mM K+ 5 mM 150 mM Simple Diffusion inside outside K+ K+ Na+ Na+ Membrane Potential and Action Potential Nerve and muscle cells = Excitable Membranes Can rapidly change membrane permeability to Na+ and K+ by opening gated ion channels Membrane potential can undergo rapid changes away from resting level = electrical signal igugelisim gelisimedu Membrane Potential and Action Potential Action potentials: are rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane.  Membrane Potential and Action Potential Resting Stage: This is the resting membrane potential before the action potential begins. The membrane is said to be “polarized” during this stage because of the –90 millivolts negative membrane potential that is present. Membrane Potential and Action Potential Depolarization Stage: At this time, the membrane suddenly becomes very permeable to sodium ions, positively charged sodium ions to diffuse to the interior of the axon. The normal “polarized” state of –90 millivolts is immediately neutralized by the inflowing positively charged sodium ions, with the potential rising rapidly in the positive direction. This is called depolarization. Membrane Potential and Action Potential Repolarization Stage: Within a few miliseconds after the membrane becomes highly permeable to sodium ions, the sodium channels begin to close and the potassium channels open. Then, rapid diffusion of potassium ions to the exterior re-establishes the normal negative resting membrane potential. This is called repolarization. Recommended Reading Ganong’s Physiology Lippincott’s Physiology igugelisim gelisimedu  | WHAT TO TAKE HOME? | Cell Structure: Cells are fundamental units of life, with organelles that perform specific functions. Cell Membrane: Regulates the movement of substances in and out, maintaining homeostasis. Transport Mechanisms: Passive Transport: Moves substances without energy. Active Transport: Requires energy to move substances against their gradient. Vesicular Transport: Includes endocytosis (bringing in) and exocytosis (releasing). Ion Channels and Pumps: Essential for maintaining electrical balance and cell communication. Health Implications: Dysfunction in transport mechanisms can lead to diseases. Real-Life Applications: Knowledge is crucial in medicine, pharmacology, and biotechnology.  | QUESTIONS AND SUGGESTIONS | Questions: What are the key differences between passive and active transport? Can you give examples of diseases caused by cell transport dysfunction? How do ion channels facilitate cell communication? What lab techniques study cell transport mechanisms? How do medications affect cell transport processes? Suggestions: Use models or simulations to visualize cell structures. Engage in group discussions about real-world transport examples. Research specific transport-related diseases for presentations. Invite healthcare professionals to discuss the topic. Incorporate quizzes and games to reinforce learning.  | RECOMMENDED WEEKLY STUDIES | Reading Assignments: Review textbook chapters on cell structure and transport mechanisms. Diagrams and Models: Create diagrams or 3D models of cells and their organelles Interactive Activities: Use online simulations to visualize transport processes like diffusion and osmosis. Videos and Lectures: Watch educational videos on cell physiology; take notes on key points. Practice Questions: Complete quizzes related to cell transport mechanisms. Reflection and Summarization: Write summaries of what you've learned and create flashcards for key terms. Research: Explore real-life applications of transport mechanisms in medicine and biotechnology.  | REFERENCES | "Human Physiology: From Cells to Systems" Authors: Lauralee Sherwood A comprehensive introduction to human physiology, emphasizing the integration of organ systems. "Essentials of Human Anatomy & Physiology" Authors: Elaine N. Marieb and Katja N. Hoehn This textbook provides a clear and concise overview of anatomy and physiology concepts. "Cell Biology" Authors: Thomas D. Pollard, William C. Earnshaw, and Jennifer Lippincott-Schwartz An in-depth exploration of cell structure and function, ideal for understanding cellular processes.  | ABOUT THE NEXT WEEK | Body Fluid Compartments: Understand intracellular fluid (ICF) and extracellular fluid (ECF) distribution. Electrolytes: Learn about key electrolytes (sodium, potassium, calcium) and their roles. Fluid Balance: Examine how the body regulates fluid balance through thirst and hormones (ADH, aldosterone). Movement of Fluids: Explore how fluids move between compartments and factors influencing this movement. Clinical Relevance: Understand conditions related to fluid and electrolyte imbalances (e.g., dehydration, edema).  ………….. – ………………………… Since course presentations are private, using the texts and images contained herein on social media or else without permission from the course instructor is against the regulations Law No. 6698.