Ch.1 Introduction to Physiology and Homeostasis 2024/2025 PDF

Physiology (0603302) CH.1 - Introduction to Physiology and Homeostasis - Cell structure, membrane Transportation and membrane potential 1st semester-2024/2025 Dr. M...

Physiology (0603302) CH.1 - Introduction to Physiology and Homeostasis - Cell structure, membrane Transportation and membrane potential 1st semester-2024/2025 Dr. Mohammad A. Abedal-Majed School of Agriculture The University of Jordan Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 1  Study Questions You should be able to answer the following questions and understand the related concepts. 1. What is the purpose of studying physiology? 2. What are the different levels of organization? What are the primary tissue types found in human? 3. What are the typical functions of an epithelium? 4. What are the fluids in the human body? What are the factors affecting body fluids? 5. What is homeostasis and how do feedback mechanisms help to ensure or prevent homeostasis? 6. What is the major component of the cell membrane and what is the chemical characteristics of this component? 7. How is diffusion defined and what factors determine the rate of diffusion of a solute? 8. What factors determine the permeability of the membrane for a given molecule (e.g. O2, Na+, glucose)? 9. What are the different types of channels? How is the conformation of the channel regulated?  Study Questions 10. What is the difference between a channel and a carrier protein? 11. What determines the maximum rate of facilitated diffusion? Active transport? 12. How does the Na+-K+-ATPase transport ions across the cell membrane? Why is this transporter important for the function and integrity of the cell? 13. How is secondary active transport different than primary active transport? What is the energy source for each mechanism of active transport? 14. What factors determine the rate of osmosis? What is the relationship between forces driving water movement and pressure differences between the inside and outside of the cell? 15. What happens when a cell is placed in a hypotonic solution? Hypertonic solution? 16. Does water only move via simple diffusion?  Anatomy & Physiology Anatomy – the study of the structure of the human body Physiology – the study of the function of the human body Understanding the relationship between physiology's structure and function requires knowledge of anatomy. Because structural design makes it possible for physiological mechanisms to operate, each organ's structure is created in a way that enables proper performance of its function. Example: the chest cavity, which is made up of the ribs, surrounds and protects the heart and lungs while also moving during inspiration and expiration to aid in breathing. The body is structurally organized into a whole functional unit Dr. Mohamed Abedal-Majed (11-2-2023) 4 Physiology is the science of life  Levels of Organization 1- Chemical 2- Cellular 3-Tissue 4- Organs 5-System Level 6- Organismic Level Organism (the whole body): made up of the 12 systems Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 5  Levels of Organization 1-Chemical level: atomic and molecular level Atom (smallest part of the body): Oxygen, Nitrogen, Carbon and hydrogen, etc. Molecule(un-living things made up of atoms) : water, CO2, CHO, Proteins. 2-Cell (made-up of many molecules) muscle cell, nerve cell, etc. -The basic live organizational structure of the human body is the cell The smallest thing that can perform life's necessary processes 3-Tissue:epithelia, connective, muscle and nerve (Group of similar cells (structure & specialized functions) that work together on one task) Dr. Mohamed Abedal-Majed (11-2-2023) 6  Few cells surrounded by a lot of extracellular material exchange substance supporting between the cell and and securing different its environment body parts Sheet: to protect the body organs Gland: its secrete hormones and enzymes a) Smooth muscles: in blood vessels wall and uterus, and Initiating & transmitting electrical impulses internal organs b) Skeletal muscles: to move the body c) Cardiac muscles: to pump initiating and the blood. transmitting nerve impulses contracting and generating force Abedal-Majed (11-2-2023) Dr. Mohamed 7 Physiology is the science of life  Levels of Organization 4-Organ – skin, femur, heart, kidney, etc. consists of two or more types of primary tissues that function together to perform a particular function or functions Example: Stomach Inside of stomach lined with epithelial tissue Wall of stomach contains smooth muscle Nervous tissue in stomach controls muscle contraction and gland secretion Connective tissue binds all the above tissues together Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 8  Levels of Organization 5-Body System – skeletal system, digestive system, etc. collection of related organs with a common function, sometimes an organ is part of more than one system 6- Organism – the human (one living individual) 9 Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023)  Levels of Organization We have 3 opening between inside and outside the body: Respiratory system: take O2 and eliminate CO2 Digestive system: take the food, and eliminate the unabsorbed food. Urinary system: to eliminate waste products from the body. Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 10  Body Fluids (Total body water of healthy adult= 60 % BW) depend on age and gender -As age increase, the total body water content decrease (About 80% of the body of a new born is fluid) -A health female adult body is 50-55 %fluid, because females have more fatty tissues 100 kg male= Body water= 100*(60/100)= 60% Why water ? Why not other liquid? 1- Specific heat: water is the most difficult liquid to boil or to freeze 2- Capillary action (tears and breastfeeding) 3- Excellent solvent (Na+, K+, Cl- can dissolve in water and pass through channels) 4- Redox reactions to kill bugs “ROS” Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 11  Body Fluids A-Extracellular fluid (ECF) (1/3)- Fluid environment in which the cells live (fluid outside the cells) (Ions, O2, nutrient, waste) Two components: 1-Plasma (Inside the blood cells) 2-Interstitial fluid (Around the cells) B-Intracellular fluid (ICF) (2/3) - Fluid contained within all body cells High Level of K+ and less Na+. It has protein –ve charge 40% of the total BW 20% of the total BW Why more water in ICF? ( Dr. Mohamed Abedal-Majed (11-2-2023) Physiology is the science 12 of life Why more water in interstitial space? Male BW= 70 Kg Total body water= 70kg* (60/100)= 42 Kg or L ICF= (2/3)*42=28 or 70* )40/100) =28 ECF= (1/3)*42=14 or 70* )20/100) =14 Plasma = (1/4)* 14= 3.5 L ISF= ( 3/4)*14= 10.5 L Q2 ECF= 25 BW= 85 ICF= 85-25= 60 L Physiology is the science of Dr. Mohamed Abedal-Majed (11-2-2023) 13  Balancing the Internal and External Environment Cells, the fundamental units of life, exchange nutrients and wastes with their surroundings: The intracellular fluid is “conditioned by”… the interstitial fluid, which is “conditioned by” … the plasma, which is “conditioned by” … A-Extracellular fluid B-Intracellular fluid (ICF) the organ systems it passes through. ICF ISF plasma organs external environment internal environment Internal environment = fluid surrounding cells (EXTRACELLULAR FLUIDS) 14 Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023)  Homeostasis Homeo=same; stasis=standing Maintenance of Relatively Constant/stable of the internal environment (extracellular fluids). Maintaining a dynamic steady state in the internal environment The internal environment remains relatively constant though there are changes in the external environment (Does not mean that composition, temperature, and other characteristics are absolutely unchanging) stable =/= rigidity, can vary within narrow limit (normal physiological range) The golden goal of every organ : to maintain homeostasis Homeostasis is essential for survival and function of all cells Each cell contributes to maintenance of a relatively stable internal environment Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 15 Factors Homeostatically regulated 1- Concentration of nutrients ( glucose, O2, CO2, and waste products) 2- Concenytration of water, salt, and other electrolytes 3- pH 4- Blood volume and pressure 5- Body temperature Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 16  Homeostasis & Controls Successful compensation Homeostasis reestablished Failure to compensate Pathophysiology Illness Death Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 17  Homeostatic Control Mechanisms Monitors aspects of the internal environment and corrects as needed. Variations are within limits. There are three (3) parts: -Receptor - provides information about the stimuli -Control Center - tells what a particular value should be (called the set point) -Effector - elicits responses that change conditions in the internal environment Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 18  Regulation of Internal Constancy = Homeostasis Homeostasis is NOT a static state – dynamic changes around a setpoint Relies on Negative Feedback loops sensor monitors internal conditions, detects changes integrating center (controller) receives & integrates information effector responds to changes activity of effectors results in return of condition to normal levels. Dr. Mohamed Abedal-Majed (11-2-2023) 19 Physiology is the science of life  Homeostatic Control Mechanisms 1. Feedback Control (Positive, and negative) 2. Feed-forward control Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 20  Negative feedback Negative feedback summary: 1-We have initial change, lead to a response. 2- So we will have other thing happen to suppress the Change initial response. For example: when we eat food>> glucose will increase in the blood.>> The pancreas will sense this glucose increasing, so it will secrete hormone called insulin. >> Insulin will decrease the blood glucose. most feedback systems in the body are negative used for conditions that need frequent adjustment Examples: body temperature, blood pressure & glucose 21 regulation Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023)  Positive feedback Positive feedback summary: The initial change lead to a response. The response increase the initial change. short-lived do not require continuous adjustments  Examples:  Blood clotting (What do you think will happen if its not regulated)  Urination  LH increase before ovulation  Na+ inflow in genesis of nerve signals  Contraction of the uterus during childbirth Dr. Mohamed Abedal-Majed (11-2-2023) 22 (parturition) Physiology is the science of life  Feed-forward control Response is made in anticipation of a change. Direct effect of stimulus on the control system before the action of feedback signal occurs. (adaptive feedback control) (prepare the body for the change) Example: 1-Shivering before diving into the cold water 2-The process of salivation, when we smell the food before we eat, the body start to secrete saliva. Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 23  Human Cell -Human being is a multicellular composed of different type of cells. There are 50-100 trillion cells in the human body. Differentiation is when cells specialize!!!!!, whereas the specialized contributions and interactions among cells of multicellular organisms are essential for survival of the whole body). As a result of differentiation, cells vary in size and shape due to their unique function. Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 24 Basic Cell Functions: Cell functions 1- Obtaining nutrients and oxygen from the environment surrounding the cell. 2- Performing chemical reactions that use nutrients and oxygen to provide energy for cell. 3- Eliminating CO2 and other wastes products which is the end product of chemical reactions (Metabolism) 4-Synthesizing needed cellular components (e.g protein by organelle called ribosome) 5- Controlling the moving of materials outside the cells and control exchange materials. 6- Sensing and responding to changes in the surrounding environment. 7- Reproduction of new cells except Nerve and muscle cells because they lose their ability to reproduce during their early development (during embryonic life) Specialized Cell Functions: each cell has its special function ( For example: white blood cells: phagocyte foreign materials. While the red blood cells carry oxygen ) Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 25  Cell Membrane -The cell has a thin and mechanically weak membrane Each cell is bounded by a cell membrane (also known as the plasma membrane) -Its thickness 7.5-10 mm and we mean by mechanically weak that it is easy to be broken. Functions : 1.Maintaining the structural integrity of the cell 2.Controlling movements of substances in and out of the cell (selective permeability) 3.Regulating cell–cell interactions 4.Acting as an interface between the cytoplasm and the external milieu Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 26  Cell membrane is important Why??  Because the cell membrane is very important, it creates a barrier between the ICF and the ECF  If the cell membrane breaks, the cell dies.  Cell membrane creates and maintains concentration differences between the intracellular and extracellular solutions. 1- Much higher K+ conc. Inside than outside. 2- Much higher Na+ conc. outside than Inside. 3- Much higher Cl- conc. outside than Inside. 4- Much higher Ca++ conc outside than inside. 5- Higher protein conc inside than outside. 6- Outside is slightly alkaline (PH=7.4) while inside is neutral (PH=7). Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 27  Composition of the cell membrane Protein 55% Phospholipids 25% Cholesterol 13% Lipids???? Other lipids 4% Carbohydrates 3% The cell membrane is permeable to certain substance and impermeable to other substance, it allows lipid soluble material to cross it and the lipid insoluble (water Soluble) can’t cross so it passes through channels Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 28  Cell Membrane Phospholipids which are the major component of the plasma membrane are amphipathic molecules Phospholipid bilayer Water-soluble “heads” form surfaces (hydrophilic) Water-insoluble “tails” form interior (hydrophobic) Permeable to lipid-soluble substances Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 29  Movements Into and Out of the Cell Passive (Physical) Processes Active (Physiological) Processes Net movement down Net movement against a a concentration gradient concentration gradient (high concentration to an needs energy area of low concentration.)  does not need ATP Primary Active transport Note: in equilibrium the net movement is zero Secondary Active transport 1- Simple diffusion (Non-carrier mediated transport). 2- Facilitated diffusion Take home message is that 3- Osmosis (Just for water) except simple, small, neutral Diffusion, Facilitated Diffusion & Active Transport: Movement across the Cell Membrane - YouTube molecules, essentially everything GCSE Biology - Osmosis #7 - YouTube that is biologically relevant Dr. Mohamed Abedal-Majed (11-2-2023) cannot readily pass through 30 a Physiology is the science of life simple lipid bilayer membrane.  1.Simple Diffusion A B Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 31  1.Simple Diffusion  Cell membrane is permeable to: Non-polar molecules (02). Lipid soluble molecules (steroids). Small polar covalent bonds (C02). H20 (small size, lack charge).  The degree of diffusion of these substances is determined mostly by their lipid solubility. Cell membrane impermeable to: Large polar molecules (glucose). Charged inorganic ions (Na+). Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 32  1.Simple Diffusion The substances go through intermolecular spaces (directly through the cell membrane) of the membrane (simple diffusion) and these substances are a lipid soluble substance and gases  Simple diffusion occurs whenever there is a concentration difference across the membrane (the membrane is permeable to the diffusing substance). (Energy independent) Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 33  2.Facilitated Diffusion The diffusion of lipid insoluble or water soluble substance across the membrane down their concentration Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. gradients by aid of membrane Region of higher proteins concentration Substances: K+, Na+, Ca2+, glucose, amino acid, urea etc. Transported substance 2.1 Facilitated diffusion via carrier 2.2 Facilitated diffusion through channel Region of lower concentration 2.2.1 Voltage-gated ion channel Protein carrier molecule 2.2.2 Chemically-gated ion channel Cell membrane Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 34  2.1 Facilitated Diffusion via carrier  It is need help which is the substance attached to the carriers, then the carrier will change its shape allowing to release the substance to the other side of the cell membrane  The direction of transport is downhill (i.e, from high concentration to low concentration). ATP energy is not required Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 35  2.2 Facilitated diffusion via channels -Allow free movement of certain ions or molecules (channel proteins)  Two important characteristics : 1. selectively permeable to specific substances 2. opened or closed by gates A Channel gates are opened by the binding The molecular conformation of the of another molecule with the protein; gate responds to the electrical potential (Binding chemical substances to the gate across the cell membrane ( nerves, glia, (chemical or ligand gating). heart, skeletal muscle ). Primary role is action potential initiation causing conformational change in 36 Physiology is the science of life protein that opens or closes the gate. Dr. Mohamed Abedal-Majed (11-2-2023)  3.Osmosis Movement of water through a selectively permeable membrane from regions of higher concentration to regions of lower concentration It is the movement of the water from high concentration of water to lower concentration of water (and from lower concentration of solutes to higher concentration of solutes) Osmosis is important both: A- At cellular level, making cells to shrink or swell. B- At tissue level, osmosis occurs through the epithelial cells in the GIT and renal system. It also occurs through capillary walls. 37 Dr. Mohamed Abedal-Majed (11-2-2023) Physiology is the science of life  Cell membrane physiology osmotic pressure (OP): concentration of solutes inside cell - the osmotic pressure inside human cells = the concentration of 0.9% solution of sodium chloride (99.1 g water + 0.9 g NaCl) - 0.9% NaCl solution called “normal or physiologic saline” Hypotonic: OP in extracellular fluid < OP intracellular fluid  water enter the cell Hypertonic: OP in extracellular fluid > OP intracellular fluid  cell lose water out isotonic: OP in extracellular fluid = OP intracellular fluid  water is hydrostatic Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 38  3.Osmosis Blood volume must be restored in a person who has lost large amounts of blood due to serious injury. This is often accomplished by infusing isotonic NaCl solution into the blood. Why is this better than infusing an isoosmotic solution of a penetrating solute, such as urea? Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 39  4.Active Transport Carrier molecules transport substances across a membrane from regions of lower concentration to regions of higher concentration Glucose, amino acids, sodium ions, potassium, calcium, Hydrogen It is carrier-mediated (needs carrier), like the facilitated Diffusion but in active transport we need an energy uphill against an electrical or pressure gradient 4.1 Primary active transport: the energy used to cause the transport is derived directly from the breakdown of ATP or some other high-energy phosphate compound 4.2 Secondary active transport: The energy is derived secondarily from energy stored in the form of ionic concentration differences between the two sides of the membrane created by primarily active transport Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 40 4.1 Primary Active Transport 4.2 Secondary Active Transport Hydrolysis of ATP directly required for the function of Coupled transport. the carriers. Molecule or ion binds to “recognition site” on one side of Energy needed for “uphill” movement obtained from carrier protein. “downhill” transport of Na+. Binding stimulates phosphorylation (breakdown of ATP) Na+ /Glucose co-transport (the glucose it attached to the Na+): of carrier protein. Carrier protein undergoes conformational Both Na+ and Glucose (or amino acid) have to be present. change. The energy available from Na+ down its electrochemical Hinge-like motion releases transported molecules to gradient is used as an energy source. opposite side of membrane Found in the epithelial cells of the intestine. 41 Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023)  4.1 Primary Active Transport Examples: A- Na+/K+ pump which is found in all the cells. B- Ca++ active transport in cell membrane and inside the cell. It maintains low level of intracellular Ca++ (Muscle cell) C- Active transport of H found in gastric gland of stomach and distal and collecting tubules of the kidney D- H+/K+ pump (proton pump at the stomach) Creates balance by “pumping” three (3) sodium (Na+) OUT and two (2) potassium (K+) INTO the cell 3:2 ratio Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 42  4.2 Secondary Active Transport glucose Co-transporters will move one moiety, Counter-transporters will move one e.g. glucose, in the same direction as moiety, e.g. Na+/Ca++ counter- the Na+. transport in the renal Proximal tubules of the nephron Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 43  Movements Into and Out of the Cell Property Simple Facilitated Active diffusion diffusion transport Requires special membrane protein No Yes Yes Highly selective No Yes Yes Uphill transport No No Yes Requires energy No No Yes Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 44  Summary Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 45  Membrane Resting Potential  A constant potential difference across the resting cell membrane  Cell’s ability to fire an action potential is due to the cell’s ability to maintain the cellular resting potential at approximately –70 mV (-.07 volt)  The basic signaling properties of neurons are influenced by changes in the resting potential Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 46  Membrane Potential Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 47  Membrane Potential Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 48  Membrane Potential Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 49  Membrane Potential Physiology is the science of life Dr. Mohamed Abedal-Majed (11-2-2023) 50