A&P I Chapter 1-3 Notes PDF
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Summary
These notes cover Chapter 1-3 of a human anatomy and physiology course. The document details the basic structures and functions of the human body, from the chemical, cellular, tissue, organ, and organ system levels.
Full Transcript
Chapter 1: The Human Body natomy vs. Physiology A Anatomy: the various structures of the body, and theirrelationship to one another Gross anatomy: structures visible to the naked eye ○ Regional vs. systemic anatomy Regional anat...
Chapter 1: The Human Body natomy vs. Physiology A Anatomy: the various structures of the body, and theirrelationship to one another Gross anatomy: structures visible to the naked eye ○ Regional vs. systemic anatomy Regional anatomy: study the body by region Systemic anatomy: study the body by system Microscopic anatomy: structures that are microscopic (basically looking at cells) ○ Cytology vs. histology Cytology: study of cells Histology: study of tissues Physiology: how these individual body parts work (orfunction) on a normal level How does this body part keep us alive Most often considered at the cellular/molecular level Considered at the cellular level rinciple of Complementarity of Structure and Function (this is what ties anatomy and P physiology together) What a structure can do is dependent on its form/structure (physiology depends on anatomy) ○ Stomach that breaks down food has 3 layers to create strong contractions to make digesting the food easier ○ If you change the structure, you will almost always change the function Most diseases is usually due to some changes in structure How does this principle relate to anatomy and physiology? Structural Organization of the Human Body 1. Chemical level Atoms combine to form molecules 2. Cellular level The smallest unit of life Cells can grow individually in number or in size Cells can respond to stimuli Cells that have different functions will look different ○ Ex. a stomach cell will look different than a cell from your nervous system 3. Tissue level Aggregations (collection) of living cells that carry out a similar function ○ Aggregation: collection of cells ○ Cells in a tissue should all have similar functions Four basic types: muscle, epithelial, nervous, and connective What is the difference between a cell and a tissue? 4. Organ level In order for something to be considered an organ, it must be composed of 2 or more tissues that operate together to perform a certain function What is the difference between a tissue and an organ? ○ Organs will be more complex in function and more specific than tissue 5. Organ system level Multiple organs work together to accomplish a purpose Chains of organs that work together Each organ system will contribute to a broader physiology function What is the difference between an organ and an organ system? 6. Organismal level All organ systems working together to keep the organism alive ○ Ex. lung brings in oxygen that all other cells need What is the difference between an organ system and an organism? ecessary Life Function N Everything we will learn will fit into one of the following necessary life functions 1. Maintaining boundaries At the cellular level, and at the organismal level ○ At the cellular level: the plasma membrane Separates intracellular space and the extracellular space ○ Organismal level: the skin The skin is important in preventing exposure What are examples at these 2 levels? 2. Movement Cooperation of skeletal and muscular systems to coordinate actions ○ Can be conscious movements, or not ○ What is an example of this life function Voluntary: Skeletal tissue is what we control Involuntary: we do not control when it contracts Smooth muscle tissue: found in the walls of your hollow organs Cardiac muscle tissue: found in the walls of the heart ○ Lower part of the brain will control this bc you need about 72 beats/ min to stay alive and function and you would have to focus on that the whole time if it was voluntary Movement needs to occur for life to occur 3. Responsiveness Body’s ability to receive and respond to change Sensing environmental changes and responding to them Nervous system is primarily involved with excitability Two body cells that is excitable ○ Neurons ○ Muscle tissue cells Need to respond to Allows us to move fast If you touch a hot stove, you will move your hand away to prevent damage 4. Digestion (breaking down food) Food is broken down to simple molecules to be absorbed to blood and delivered to various tissues 5. Metabolism (converting food into energy 3 general categories ○ Catabolism: take large molecules and break it down to smaller parts ○ Anabolism: take smaller molecules and build it into larger molecules Ex. taking AA to build proteins ○ Cellular respiration: use ATP electron transport chain produces well over half of the ATP needed 6. Excretion Removal of waste produced during digestive and metabolic functions ○ These waste products usually have some toxic effect Ex. CO2 and nitrogenous waste is disposed ○ Nitrogenous waste is excreted through the urinary system 7. Reproduction Cellular levels: cells must divide for organism to survive There are some processes that will kill off some cells and other processes that will build/repair that so the tissue doesn’t fall apart? This is the only one that doesn’t necessarily have to happen bc not everyone needs to reproduce, but at least some in the population needs to reproduce 8. Growth Increase in the number of body cells, or increase in size of individual cells themselves Building must occur faster than break down in body in order for growth to occur ○ Anabolic reactions have to exceed catabolic reaction Survival Needs Survival need vs necessary life function In order to carry out all of the necessary life functions, you have to have these survival needs 1. Nutrients Brought into body by ingestion Includes carbohydrates, fats, proteins along with vitamins and minerals ○ Carbohydrate and protein: macronutrients bc we need a relatively large amount of it ○ Vitamins and minerals: micronutrients Vitamins are important for Minerals are structurally important bc minerals are used to build things 2. Oxygen Oxygen is required for ETC which is required to make most of your body’s ATP Cells can only survive a few minutes without oxygen 3. Water Provides environment for chemical reactions and serves as fluid base for secretion and excretion ○ Excretion: specifically waste disposal (usually referring to urinary system) ○ Secretion: the process of which the body removes something the body reproduces Secretion is not necessarily getting rid of something Secretion: a process by which substances are produce and released by a cell or gland for a particular function Ex. sweat glands produce and secrete sweat which is released to the body surface Most of the water is found in body cells Water is important bc it is a solvent Chemical reactions occur in water Some of our important life function use water 4. Endothermy We generate our own internal body heat and be maintained Body temperature must be maintained for chemical processes to occur 5. Atmospheric pressure Breathing and gas exchange occur at an appropriate atmospheric pressure If you increase or decrease atmospheric pressure, or body might not be able to get enough oxygen Sea level is optimal atmospheric pressure Atmospheric sickness: people get this when they go somewhere with atmospheric pressure they are not used to so they don’t get enough oxygen Homeostasis Homeostasis is the maintenance of the internal condition of the body despite a constantly changing external environment ○ This maintenance is not a static state Homeostasis is not static so it does not just stay in one place, you can hover around the optimal state ○ Accomplished by the work of virtually all organ systems Control of homeostasis ○ Mostly regulated by nervous system and endocrine system Nervous system: the brain tells organs to increase/decrease function at certain times Ex. when you eat food, your brain tells your stomach muscles to contract to digest it Endocrine system: produce and release hormones These systems are not all connected, they are spread out throughout the body ○ Variable: what organ or function is being controlled or regulated 3 parts (or mechanisms) involved in variable control/regulation 1. Receptor: some cell type that receives information about the variable Ex. thermal regulation and body temperature ○ Thermal receptors scattered throughout the body and will receive information abt your body temp and will make a message that will send the message to the control center (usually the brain btu sometimes the spinal cord) ○ Brain receives the messages and will interpret it and figure out what it means (is the body temp too warm/ too cold) ○ Once it figures out what the message means, the control center sends out a response message which will be received by the effector ○ The effector is the part of the body that carries out the response Effector in this case is the skeletal muscle tissues and if it is too cold, your skeletal muscle tissue will start to make you shiver 2. Control center: usually the brain but sometimes the spinal cord 3. Effector: part of the body that carries out the response E ffectors are not always the same bc if you are too warm, the effectors will be your sweat glands and if you are too cold, it will be the skeletal muscle tissues Homeostasis is controlled by negative feedback mechanisms or positive feedback mechanisms ○ Negative feedback mechanism: causes the variable to change in a direction that is opposite of the initial change Ex. thermoregulation, most hormones ○ I f your body temp drops, it will tell muscle skeletal glands to bring it back up to the normal range (about 98.6 degrees) ○ If your body temp rises, it will tell sweat glands to bring it back down to the normal range ○ Positive feedback mechanism: causes the original change of the variable to be enhances (ex. Accelerates the change) Negative feedback: you don’t want a big change Positive feedback: you want a big change Do not control events that require frequent, small adjustment Ex of positive feedback: labor, blood clotting Blood clot: build up of blood really quickly to prevent blood from leaking Positive feedbacks tend not to last long while negative feedback happens constantly Negative feedback mechanism is more common than positive feedback mechanism Imbalances in homeostasis ○ What can create an imbalance in homeostasis? Aging leads to homeostatic imbalance Control systems become less efficient, making us more susceptible to disease Cascade of events caused by positive feedback mechanisms can overpower negative feedback mechanisms Most variables are controlled by negative feedback mechanism I f something goes wrong, that variable gets controlled by a positive feedback mechanism (drastic increase in activity) Autoimmune disorders: body cell starts attacking its own body cells ○ ○ All known diseases/disorders/conditions are due to some imbalance in homeostasis natomical Terms A Position & Directional Terms Reference point: anatomical position ○ Right vs left is always viewed in terms of the person being observed, not your own If someone raises their right hand, it is their right hand, even if you view it and it is to your left Directional terms: help us explain one body part in relation to the others ○ Dorsal (posterior) vs. ventral (anterior) Dorsal: back side Ventral: belly side ○ Lateral vs medial Medial: closer to the middle Eye is medial to ear Lateral: further apart Ear is lateral to eye ○ Distal vs proximal Distal: relative to the point of origin Wrist is distal to shoulder In lab, we learned that distal means lower so the toe is distal to the knee Youtube: point of origin refers to the trunk of the body ○ Distal means further away ○ Proximal means closer to body ○ Ex. elbow is distal to the shoulder ○ Ex. shoulder is proximal to the fingers Proximal: nearby In lab, we learned that distal means lower so the knee is proximal to the toe ○ Deep vs superficial Deep: further away from surface Superficial: closer to surface ○ Superior vs inferior: top vs bottom Superior: head is superior to neck Inferior: neck is inferior to head Body Planes: ○ Sagittal: divides body into left and right median/midsagittal plane divides the body exactly in half ○ Frontal: divides body into anterior and posterior ○ Transverse: divides body in superior and inferior parts ○ Body cavities ○ Most organs are found in one of the body cavities ○ Dorsal body cavity: protects organs of the central nervous system (CNS) Composed of the cranial cavity and spinal cavity ○ Ventral body cavity: houses visceral organs Composed of: Thoracic cavity: contains heart and lungs Abdominopelvic cavity: separated from thoracic cavity by diaphram Ventral body cavity is everything elses but the CNS (dorsal body cavity) Membranes of the Ventral Body Cavity ○ Serous membrane (serosa): double-layered membrane Visceral serosa: innermost layer covering the organ Parietal serosa: outer layer lining the body wall of the cavity These 2 layers sit close to each other but don’t touch each other 2 layers are separated by a small amount of serous fluid (has an oily type of texture) ○ What is the importance of this fluid? You don’t want visceral and parietal serosa rubbing against each other bc it can cause damage Serous membrane protects your organs Ex. when your heart beats, it can rub up against other organs and the serous membrane prevents this V isceral and Parietal serous membranes protects each side of the lung bc if there is damage in one side of the lung, it will prevent it from spreading to the other side? Visceral clings to the heart and the parietal clings to the body cavity and there is serous fluid between the visceral and parietal serosa to prevent them from rubbing on each other Serous membranes are named according to their location 1. Pericardium: serous membrane surrounding the heart ○ There is a visceral pericardium and a parietal serous 2. Pleura: serous membranes surrounding the lungs 3. Peritoneum: serous membranes surrounding most organs of the abdominopelvic cavity Chapter 2: Chemistry ixtures M Mixtures: any substance containing 2 or more componentsphysically intermixed In anatomy, for the most part, mixtures will be liquid Types of mixtures 1. Solutions: homogenous mixtures that can exist as asolid, liquid, or gas composed of very small particles that do not settle out Solventis the dissolving medium ○ Water is the body’s primary solvent Soluteis dissolved in solvent and is usually thebigger amount than the solvent ○ Ex. saline solutions (water + NaCl) ○ Remains suspended ○ Solvent is equally distributed in the solute bc a solution is homogenous Concentration of a solution can be described using: 1. Percent solution: amount of solute dissolved is expressedas a percentage of the total solution volume 2. Molarity(mol/L): the number of moles of a substanceper liter of solution Reminder: a mole of any element or compound is equal to its molecular weight 2. Colloids: heterogenous mixtures composed of largesolute particles that do not settle out They are homogenous like solutions???? ○ Solvent is suspended ○ Different from solution: colloids have bigger particles while solutions have smaller particles Can undergosol-gel transformation→ mixture can changefrom a fluid state to more solid state (and back again) ○ Ex. cytosol of cells changes consistency depending on certain cell activities (cellular division, change in space, etc.) ○ More solid state → not solid solid but it can go from a liquid state to more of a jello state ○ Fluid can become thicker or thinner depending on what the cell needs Thicker = more compact? . Suspensions: heterogeneous mixture composed of largesolute particles that do 3 settle out Unlike collaids which have particles that will not settle out of the solution? Ex. blood contains a fluid portion (called plasma) with various cell types (red blood cells, white blood cells, & platelets) suspended in it ○ Plasma sits on top when it separates out from the blood Chemical Reactions Occurs when chemical bonds are formed, broken, or rearranged ○ Chemical bonds are stored energy Types of reactions: 1. Synthesis reaction: formation of bonds between atomsor molecules to form larger, more complex structures Areendergonic→ contains more energy after formation ○ Need energy to form those bonds Ex. anabolic reactions in the body 2. Decomposition reaction: bonds are broken to create smaller molecules or individual atoms Are (mostly)exergonic→ release energy when bond is broken ○ Can be endergonic Ex. catabolic reactions in the body Inorganic Compounds & Their Roles in Homeostasis 1. Water: makes up most of the total body mass and mostof the volume of individual cells Importance in homeostasis: ○ Universal solvent Transport → water carries nutrients, respiratory gases, metabolic waste, etc. Water can surround some charged structures (ex. Large proteins) to prevent interactions with other charged particles You wrap things in water so that that thing doesn’t make contact with anything else on it’s way to its destination and cause a reaction ○ High heat capacity Heat capacity: the amount of heat that a substance needs to absorb in order to raise its own temp by 1 degree Celsius Can absorb and release large amounts of heat with little change to its own temperature Why is this important for homeostasis? Various metabolic processes releases a very large amount of heat and water’s high heat capacity helps keep our internal temp stable ○ Protection Protection is more physical than chemical Water-based body fluids provide a “cushion” for internal organs Ex. if you get hit, water will protect your organs from physical trauma Why is this important for homeostasis? ○ Heat of vaporization is high Large amount of heat must be absorbed to break bonds & cause evaporation Heat of vaporization is specific to sweating → allows sweat to absorb a lot of our heat which means we don’t have to lose too much water to cool down When our internal temp increases, it vaporizes out from the skin (sweat) Why is this important for homeostasis? ○ Reactive Water is used in several chemical reaction in the body or produce it Hydrolysis reaction vs dehydration synthesis ○ Hydrolysis reaction: take a large molecule and you add water to break the bond Ex. compound AB + H2O → A-H + B-OH ○ Dehydration synthesis: remove a water molecule Ex. A-H + B-OH → AB + H2O Why is this important for homeostasis? Without water, a lot of chemical reactions will stop if it is hydrolysis-based 2. Salts: dissociate (breaking down into positive and negatively changed ions) in solution to form electrolytes (electrolytes are water + the positively charged ions) Importance: electrolytes Na+ and K+ allow for musclecontraction and transmission of nerve impulses, Fe+ used to carryO2, etc. Iron is found in red blood cells and in responsible for binding to oxygen? For the body to use for ATP production Sodium and potassium are required for the production of electrical pulses for nervous cells and muscle cells 3. Acids & Bases: also form electrolytes Acids: release H+ ions in solution ○ Cause pH to drop Bases: release OH- ions in solution ○ Causes pH to increase Optimal blood pH is 7.2 - 7.4 ○ Ideal bc all out body’s chemical reaction occur within this range ○ Why is this important for homeostasis? Potential problem: high/low pH disrupts cellular activity, hydrogen bonds, etc. ○ Chemical reactions either stop or proceeds at a rate not sustainable for life when blood pH is outside of the optimal range Solution?Buffers Weak acids release some (but not all) H+ ○ Strong acids will release all of their hydrogen ions ○ When would this occur? When blood pH becomes too high (basic) Weak bases tie up excess H+ when pH becomes too acidic ○ When would this occur? Increase blood pH when it becomes too low (acidic) Result: buffers prevent large changes in pH that could cause excessive damage in the body ○ I t will change the pH but it will be a small change that your body can handle? Organic Compounds & Homeostasis All organic molecules found in the body contain carbon ○ Why? 1. It iselectroneutral→ it neither gains nor loseselectrons → it shares it equally 2. Can form molecules of various shapes (long chains, rings, etc.) that all have specific functions in the body Long strands can help build fiber (gives it the ability to stretch and return to original shape) DNA are ring-shaped Macromolecules: polymers that are made up of severalsmaller, identical subunits called monomers ○ Carbohydrates, proteins, and lipids 3 Types of Macromolecules: Carbohydrates, Lipids, & Proteins Macromolecules are large in size and are made up of smaller particles (micromolecules?) 1. Carbohydrates: sugars and starches Monomer:monosaccharides ○ Monosaccharides: glucose, fructose, galactose Glucose is most important of the 3 What the cells use to make ATP The cells can use fructose and galactose to make ATP, but not directly ○ It has to convert fructose or galactose to glucose ○ Monosaccharides can form disaccharides, polysaccharides Can disaccharides and polysaccharides be used directly by the body? Yes but not for energy production You have to use glucose for ATP production Major functions: ○ Fast, easy-to-use energy source ○ Cell-cell interactions → carbohydrates attached to cell surface, used to communicate Polysaccharides are important for cell-to-cell interactions Your body cell will use those polysaccharides which have stuff pointing ot? (unique to each person) to identify other b ody cells so it knows what belongs in the body and what doesn’t 2. Lipids 3 types of lipids a. Triglycerides Monomer:fatty acids and glycerol Varieties of triglycerides: ○ Saturated: contains only single covalent bonds, molecules packed closely together Saturated fat tends to be solid at room temp bc the molecules are packed so close to one another Saturated fats can stick to the inside of your blood vessels which wil cause it to be blocked off in time which is why people are told to only eat it in moderate amounts ○ You don’t want the blood vessels to your heart to be blocked bc this will cause the heart muscles to die off and cause a heart attack Ex. fat found in meat products ○ Unsaturated: contains 1 or more double covalent bonds, molecules more spread out which causes it to be more liquid at room temp Not entirely double bonds Considered to be more healthy compared to saturated fats Ex. most plant-based oils ○ Trans fat: oil fats that have a H added at sites ofdouble bonds Tends to be more solids at room temp Tends to be the worst for you and will stick to your blood vessels Ex. doughnuts, cookies ○ Omega-3 fatty acids: oil fat found in cold-water fish Ex. krill oil, fish oil capsules, salmon Considered the healthiest of the fat Considered liquid in room temp Major functions: protection, insulation, fast & easily accessible energy storage ○ Lipids stored in adipose tissue? Fat tissue? b. Phospholipids Modified triglycerides with 2 fatty acid chains and a phosphate group/head ○ Fatty acid chains are hydrophobic (don’t want to interact with water) ○ Phosphate “head” is hydrophilic (doesn’t necessarily want to touch it but can touch water with no problem) Major functions: used to build cell membranes (phospholipid bilayer) c. Steroids Most important steroid for life: cholesterol ○ Cholesterol is used to make all the other steroids so without it, you won’t have any of the other steroids ○ Ingested in eggs, meat, cheese ○ Liver produces cholesterol Produces roughly 85% of your daily amount of cholesterol so you only need to provide 15% of cholesterol from your diet 1 egg a day is enough for your daily cholesterol, eating more can cause cholesterol to build up in your blood vessels Major functions: structural component of cell membranes, is “base” used by body to form other steroids (steroid hormones - testosterone & estrogens, corticosteroids) ○ Important structurally in the plasma membranes of your cells ○ Cholesterols is important for making the cell membrane more stable and more tough It prevents the plasma membrane from breaking/tearing as easily 3. Proteins Monomers: amino acids ○ Specific amino acid sequence leads to large variety of protein functions ○ Different AA combo lead to different proteins so different functions Structure determines function! a. Fibrous proteins: proteins form long strands thatcan link together to form long, stable structures Function(s): provide mechanical support & tensile strength, some contractile ability T hey are tough so it will return to its original length even after it is pulled Ex. collagen (skin has to stretch), muscle, joint tissue (gives it flexibility), ligaments (bone-to-bone → when you bend a joint?) b. Globular proteins: compact, spherical in shape Chemically active (doesn’t mean they are enzymes) Function(s): transport molecules, immune defenses, regulation of growth & development, etc. ○ If a lipid-based molecule needs to be moved through your bloodstream, you need to bind it to a globular protein c. Enzymes: biological catalysts Function: catalysts lower the activation energy of chemical reactions Varying degrees ofspecificity ○ Some enzymes only catalyze 1 reaction, others can catalyze multiple reactions Importance: without enzymes, most reactions in the body would either not occur or would occur too slowly tosustainlife (individual will die before the reaction is complete) ATP & Cellular energy ○ Adenosine triphosphate(ATP) is *the* energy-transferring/ energy-providing molecule of any body cell What is required to produce ATP? oxygen ○ ATP has a triphosphate tail that has high bond energy (a little unstable so it will transfer a phosphate tail to make it more stable) When a phosphate tail is transferred to another molecule, that molecule temporarily has more energy to do work While doing the work, the molecule loses the phosphate group ATP storage & release is similar to energy needed to drive most chemical reactions What does this mean? Why is it important? There is very little storage of ATP when it comes to body cells A cell only produces as much ATP as it needs at that moment A TP sitting around that doesn’t do anything is a waste of energy Importance: without ATP, chemical reactions stop, cell transport stops, muscle cannot contract All of these lead to body cells dying → death occurs Lack of oxygen is death Chapter 3: Cells: Plasma Membranes The Cells Prefix: “cyto-” (ex. cytoplasm) Suffix: “-cyte” (ex. osteocyte) ○ -cyte means it is a cell The cell is the smallest living ○ Different types of cells have different functions in the body What allows cells to have different functions? Microscopic anatomy & the different type of organelles they have ○ Loss of homeostasis in cells often lead to disease Despite the differences in function, every cell has 3 basic parts 1. Plasma membrane: outermost boundary, selectively permeable 2. Cytoplasm: intracellular fluid Suspends things in the cells Mostly water, but also contains salts and organic molecules 3. Nucleus: controls cellular activities Not all of our body cells have a nucleus ○ Ex. red blood cells, thrombocytes (help with blood clotting and they don’t need a nucleus bc they don’t live very long) Plasma Membrane Fluid Mosaic Modeldescribes the general structureof the plasma membrane ○ Plasma membrane consistent of a phospholipid bilayer with proteins randomly dispersed in it ○ Fluid part of the name means the membrane ○ Mosaic is the proteins that are stuck in the plasma membrane Some of these proteins are mobile Importance: separates the intracellular fluid (ICF) and the extracellular fluid (ECF) Phosphate heads are hydrophilic so they don’t mind water ○ ICF and ECF are mostly water Fatty acid tails are hydrophobic ○ I f there is a small tear in the membrane, the fatty acid tails will aggregate so that they prevent water from touching them and it will basically repair the small damage ○ This is a limited function bc if there is a large tear, the cell won’t survive Chemical Composition of Cell Membranes 1. Lipids a. Phospholipids: forms a basic structure of membrane PolarPhosphate head: hydrophilic portion contactICF or ECF NonpolarFatty acid tails (2): hydrophobic portionsthat face the inside of the membrane Aggregation of hydrophobic and hydrophilic regions lead to ability of cells to reseal when damaged/torn b. Cholesterol: provide structural support to “stiffen” the membrane → increases membrane stability 2. Proteins:constitute most of the cells specializedmembrane functions 2 types of membrane proteins by location ○ Integral proteins: embedded in the plasma membrane Transmembrane proteinsspan the entire width of themembrane Major functions: transport protein, carriers, enzymes, receptors, cell-cell recognition, etc. ○ Peripheral proteins: loosely attached to the integralpotein Are not found *in* the lipid bilayer Major functions: enzymes, motor proteins, cell-cell attachment 6 types of proteins by function: 1. Transport proteins: move substances in and/or outof cells Some proteins (left) form channels through which a particular solute can be selectively moved ○ What does “selectively” mean? They allow a limited type of substance to pass through Other proteins (right) actively pump substances across the membrane surface by using ATP E x. Sodium Potassium ATase pump moves sodium and potassium ions in and out of the cell There has to be some conformation change to the transport protein for things to move in and out of the cell 2. Receptor proteins: can relay messages to cell interiorwhen protein is bound to/exposed to certain chemical messengers When a signal (enzyme?) binds to the receptor, the receptor will change shape which can open up or close up the protein to let things in or out Specificity to chemical messengers can vary bc signals and receptors are specific to each other When bound to chemical messenger → protein changes shape, leading to series of changes inside the cell Ex. receptor protein binds to hormone → cellular activity changes 3. Enzymes: proteins that catalyze chemical reactions Some enzymes act alone, others may act as a “team” to catalyze sequential steps ○ Each enzyme catalyzes their own part in the reaction 4. Cell-cell recognition proteins: allow body cells torecognize other body cells What type of cells in the body would need to use this type of protein? Why? ○ In the immune system, we create our own glycoproteins that are individual to us ○ Since we are all individualizes, this can help our body tell the difference between our body cells and other cells 5. A ttachment proteins: helps hold some membrane proteins in place, maintains cell shape Can be located inside of the cell or outside, depending on function 6. Intercellular junctions: some proteins are used to link cells together Length of time to link cells varies (it can be milliseconds to seconds long) Major function: assists with cell migration 3. Carbohydrates Extracellular surface is dotted with short-branching carbohydrates ○ Can be attached to membrane lipids (glycolipids) or proteins (glycoproteins) ○ Glycolipids and glycoproteins create theglycocalyx(sugar coating outside of the cell) Different cell types have different arrangements → allows for identification of cell types by other body cells Can also be used by immune cells to identify “self” cells from “non-self” cells She said think abt each cell having a specific sugar coating and your immune system only recognizes your specific sugar coating and yours Can also contribute to structure/shape of cell membrane Junctions Cell junctions: a class of proteins that provide contactor adhesion between two of more cells ○ Can be permanent or temporary ○ Types of junctions 1. Tight junction: proteins in cell membranes of neighboringcells fuse together Tends to be permanent Junction is impermeable Ex. tight junctions between epithelial cells of stomach prevent gastric juice from “leaking out” 2. Desmosomes: anchoring junctions from one cell to anotherthat prevents separation Ex. skin They are not impermeable like tight junctions Function: bind cells together to form sheets that resist shearing forces when pulled/stretched Components of a desmosome: ○ Cadherins: protein filaments extend from cell surface and link to filaments on other cell surface Blue part/ velcro looking thing ○ Inside the cell, aplaqueholds the cadherins in place Orange part Keratin filaments: hold plaque in place to prevent excessive movement/shifting ○ Cells that usually stretch have desmosomes ○ Ex. skin cells have desmosomes to allow it to stretch without the cells being torn from one another 3. Gap junctions: also called “comunication” junctions Intercellular channels between 2 cells Hollow cylinders (formed by proteins) connect adjacent cells ○ Different proteins used to create gap junctions = selective passage of molecules/substances through channels (semipermeable) Biggest function is ion exchange Gap junction are selective on what they allow movement of Membrane Transport: Passive Definition: movement of molecules across the membrane down their concentration gradient (diffusion) with no ATP required ○ Driving force of diffusion: kinetic energy of molecules In areas of high molecule concentration → molecules collide and bounce off one another more frequently How does the rate of collision affect the dispersal (or diffusion) of molecules? ○ The faster they bounce off one another means they faster they will disperse ○ The more frequently molecules collide and bounce off each other, the more frequently dispersal will take place ○ Diffusion speed determined by 3 factors: 1. Concentration: greater concentration difference between2 areas In areas of high molecule concentration → molecules collide and bounce off one another more frequently ○ The faster they bounce off one another means they faster they will disperse ○ T hey more frequently molecules collide and bounce off each other, the more frequently dispersal will take place 2. Molecular size: smaller molecule diffuse faster Larger molecule collides slower than smaller molecules ○ Diffusion takes place faster for smaller molecules than for larger ○ ALL MOLECULES HAVE THE SAME KINETIC ENERGY 3. Temperature: higher temperatures result in faster diffusion rate Colder temp decreases kinetic energy of the molecules so they collide less frequently Vice versa for hotter temp Types of Diffusion (Passive) 1. Simple Diffusion: diffusion of substance directly through the lipid bilayer Most molecules diffusing are small in size and nonpolar ○ Fatty acid tails are nonpolar so other nonpolar molecules can diffuse easily ○ Polar molecules will not be able to diffuse as easily bc fatty acid tails areb hydrophobic and don’t want to touch polar things Ex. most gases, steroid hormones, fatty acids 2. Facilitated diffusion: diffusion of molecules throughthe membrane with the used of a protein Types of facilitated diffusion: 1. Carrier-mediated: transmembrane proteins used to carry large molecules through the membrane Protein changes shape while moving substances Limits: the cell can only move substances as fast as proteins become available to move them ○ O ne side opens up and then it closes for the other side to open up and allow the substance in ○ Proteins can only move molecules one at a time?? Connects to limits??? 2. Channel-mediated: transmemebrane proteins formwater-filled channels through which molecules can pass Selective → size od channel determines what substance can/cannot pass through Proteins can form leaky or gated channels ○ Leaky: there is nothing to close the channel so whatever substance the protein is trying to transport can be transported consistently ○ Gated: means there is a door on one side of the channel so either on the intracellular side or extracellular side 3. Osmosis: diffusion of water through a selectivelypermeable membrane Movement of water across a semipermeable membrane from a less concentrated solution into a more concentrated solution unil concentration is equal on both sides of the membrane ○ Can occur without proteins or with the use ofaquaporinproteins Water loves to follow solute so water moves from a low solute concentration to a high solute concentration ○ It will move to one side of the concentration until both sides are balanced ○ Water can squeeze through the plasma membrane but aquaporin proteins can help move water molecules too Osmolarity: total concentration of all solute particles in a solution ○ A solution with a high osmolarity will have a greater number of solute particles than a solution with low osmolarity ○ One solute particle displaces one water molecule What does this mean? ○ Water moves by osmosis untilhydrostatic pressure(the pressure of water pushing on the inner cell wall) is equal toosmoticpressure(tendency of water to move into a cell by osmosis) W hen two pressures are equal → nonetmovement of water is observed When one water molecule leaves the cell, one water molecule enters the cell ○ Yellow dash line is a free permeable membrane Free permeable membrane: anything can pass Once equilibrium is reached, the volume/concentration of each side won’t change ○ H owever, we have semipermeable membranes so this is what semipermeable looks like Water loves to follow solute so water moves from left to right (from the less concentrated solution to the mre concentrated solution) Water moves to the right bc you need more water to dilute a more concentrated solution Imbalances in osmosis cause body cells to swell or shrink (depending on total water volume inside cell) ICF is contained by 300mOsm ○ If you add water, you decrease the concentration which decreases Osm (osmolarity) ○ If you remove water, you increase the concentration which increases Osm Tonicity: ability of a solution to change the shapeof a cell by altering the cells internal water volume ○ W ater will follow solutes → a change in solution concentration on either side of a membrane will also cause a change in water concentration ○ Tonicity always refers to the solution that a cell is submerged, NOT THE CELL ○ Tonicity is something you can see happen ○ The effect of solutions of varying tonicities on cell size/shape: 1. Isotonic solutionshave the same concentration ofnonpenetrating solutes as those found inside the cells Ex. a cell that’s 300mOsm, the solution will also be 300mOsm No net loss or gain of water observed If the concentration is the same on each side, what happened to cell size/shape? ○ Nothing?? Ex. 0.9% NaCl solution extracellular fluid 2. Hypertonic solutionshave a higher concentration ofsolutes than inside the cell Water moves out of the cell which will cause the cell to shrivel up Cell will “shrivel up” orcrenate Ex. 10% NaCl solution 3. Hypotonic solutionshave a lower concentration ofsolutes than inside the cell Water follows solute so it moves into the cell which causes the cell Cell will “swell up” until they burst (lyse) Ex. distilled water ecretion: a process by which substances are produce and released by a cell or gland for a S particular function Ex. sweat glands produce and secrete sweat which is released to the body surface ctive Forms of Membrane Transport A Def: movement of molecules across the plasma membrane that requires energy input (use of ATP) Why use energy? Molecules may be too big, too charged, insoluble in lipid membrane, or moving against their concentration gradient ○ Against gradient: from low to high concentrations Active transport requires transport proteins Types of active transport: 1. Primary active transport 2. Vesicular transport Primary Active Transport Def: energy required to do work comes directly from ATP hydrolysis by transport proteins called pumps Hydrolysis of ATP (breakdown of ATP) leads to transfer of phosphate group from ATP to the pump Phosphorylation of pump leads to a change in protein shape → allows protein to move molecule across the membrane Important example: Sodium-potassium (Na+ - K+) pump ○ Uses enzymes Na+ - K+ ATPase enzyme Sodium is pumped out of the cell to the ECF There are 2 binding sites on the other side of the cell for potassium ions Na- - K+ ATPase pumps sodium out of the cell and potassiuminto the cell Pumps Na+ and K+ against their gradient simultaneously& in opposite directions across the membrane Importance: ATPase pumps maintain electrochemical gradient necessary for function of muscle and nervous tissue Secondary active transport ATP is not directly used Indirectly uses energy stored in concentration gradient of ions created by primary active transport Ex. moving Na+ out of the cell creates concentrationgradient ○ Cotransportprotein pumps Na+ back into the cell, and carries glucose in to the cell with it Active Transport Systems: Number of Solutes Moved and Direction of Solute Movement 1. Symporter: movement of 2 transported substance in the same direction 2. Antiporter: movement of 2 transported substances in the opposite direction Ex. Na+ - K+ ATPase 3. Uniporter: movement of one substance Vesicular Transport (a type of active transport) Def: movement of fluids with large particles & macromolecules inside membranous sacs called vesicles Functions: 1. Endocytosis: movement of a substance into the cell 2. Exocytosis: movement of substance out of the cell 3. Transcytosis: movement of substances into, across, then out of a cell S ubstance is outside the cell, a vesicle moves the substance into the cell, across the cell, then out the cell on the other side so it is movin the substance from one side of the cell to another 4. Vesicular trafficking: movement of a substance from one area of the cell to another The substance doesn’t move out of the cell, only from one side of the cell to the other (ex. If you need an organelle in another place) Endocytosis Def: vesicular transport used to bring substance into the cell from the ECF ○ Begins with formation of infolding membrane Types of endocytosis: 1. Phagocytosis: cell engulfs large and/or solid material Forms vesicle called a phagosome ○ Pseudopod formation involves receptors → formation is specific There are receptors on the outside which is why it is specific Phagosome usually fuses with lysosome, where contents are digested ○ Lysosome are organelles that break down things ○ T he red substance is engulfed by a cell as you can see on the top where the cell membrane of the cell is connecting to release the substance into the cell 2. Pinocytosis: cell brings in a small volume of extracellular fluid containing small solute particles (phagocytosis is with big solid particles) No receptor use needed→ pinocytosis is not a specific process (unlike phagocytosis) They are sampling their environment so they know what’s going on around them By bringing in ECF, they can see if ions outside are balanced It can help produce warnings ○ N eighboring cells can produce a chemical warning that cells use pinocytosis to sense to let other cells know so they can protect themselves 3. Receptor-mediated endocytosis: allows endocytosis of specific substances to occur Like phagocytosis but with smaller substances but receptor mediated can bring substances in faster bc they are smaller Extracellular substances bind to specific receptors proteins Importance: substances can be specifically concentrated in vesicles & brought into cell Fate of contents: 1. Substance can be distributed through the cell 2. Vesicle can fuse with lysozyme for digestion of concentrated substance Exocytosis Def: vesicular transport used to remove substances from cell to the ECF ○ Secretory vesicle created around the substance to be removed What is used to form the secretory vesicle? The plasma membrane ○ Secretory vesicle travels to plasma membrane, fuses with it, and dumps contents out of the cell ○ Function: hormone secretion, neurotransmitter release, mucus secretion, waste removal Membrane Potential(potential is another word forvoltage) Selective permeability of plasma membrane generates a membrane potential (voltage) across the membrane ○ Voltage → electrical potential energy resulting from separation of oppositely charge particles (ions) All cells have a resting membrane potential → voltage difference across cell membrane when cell is at rest ○ Average of-70 mV ○ This voltage is due to the difference in charge from the inside of the cells (negatively charged) to the outside of the cell (positively charged) ○ All cells are electrically polarized Negatively charged inside Positively charged outside How is the resting membrane potential created? ○ Creation of membrane potential involves an ion imbalance on either side of the plasma membrane ○ Ion concentrations of Na+ and K+ are different on either side of the membrane Na+ concentration is higher outside the cell K+ concentration is higher insidie the cell ○ Potassium ions (K+) have pivotal role in creating the resting membrane potential ○ Plasma membranes are more permeable to K+ than to Na+ Why? ○ K+ “leaks” out of cell, proteins remain inside the cell What charge do proteins have? Negative ○ The more K+ that leaves, the more (-) charged the inside of the cell becomes ○ Some K+ ions will enter the cell → prevents inside of cell from becoming too negative How is the resting membrane potential maintained? ○ Active transport maintains electrochemical gradients to keep the cell in a steady state What allows for the active transport? Electro = charged Chemical = ion concentration What role does Na+ have in creating/maintaining the resting membrane potential? ○ Sodium plays no role in creating/maintaining the resting membrane potential, it only changes it Cells & Interactions with the Environment Cells can respond to both extracellular chemicals (hormones, neurotransmitters) and to other surrounding cells ○ These interactions are used to maintain homeostatic balance in the body ○ Plasma membrane receptors are important for allowing a cell to interact with its environment Plasma Membrane Receptors Integral proteins at membrane surface serve as binding sites Main functions: 1. Contact signaling: cellular recognition by physical contact between cells Importance: normal cellular development and immunity rely on contact signaling 2. Chemical signaling: when a chemical messenger (called ligand) binds to a specific receptor and initiates a response Overall process: ligand binds to receptor → receptor structure changes → cell proteins are altered The specific response is linked to the cell’s internal machinery (its structure & function), not the ligand itself ○ What does this mean about a ligand and its effect on different types of cells Ex. G protein - coupled receptors ○
