Physiology PDF

Chapter 1 Introduction to Physiology LECTURE: What is Homeostasis? ​ Homeostasis is the ability to maintain a relatively stable internal environment in an ever changing environment ​ Interstitial Fluid + Plasma = ECF (Extracellular Fluid) (Directly Regulated) ​ Easier to regulate EC...

Chapter 1 Introduction to Physiology LECTURE: What is Homeostasis? ​ Homeostasis is the ability to maintain a relatively stable internal environment in an ever changing environment ​ Interstitial Fluid + Plasma = ECF (Extracellular Fluid) (Directly Regulated) ​ Easier to regulate ECF than ICF because we don’t have to pass through the cell membrane. ​ Oxygen acts as a body's thermostat since plasma is the most common “hallway” which transports all throughout the body. ​ Blood CO2 rises during working out so Homeostasis regulates it ​ Yet as you are maintaining the ECF you are definitely impacting the ICF Control Systems ​ To use homeostasis we need receptor, control center, and effector ​ IN the control systems, the LOCAL control is proximal and the REFLEX control is distal ​ “Receptors detect a stimulus which is the change in the regulated variable” BLADDER ​ CNS and glands are the control centers ​ Only the control center knows your SET POINT ​ Receptor receives info from STIMULUS and relays it to the Control center which interprets and makes a decision then the effector makes a response to the STIMULUS (decrease or increase) ​ Regulated variable still gives negative and positive feedback even in range of function because we are trying to keep it around the set point Human Physiology Unit 1 Objectives Chapter 1: Introduction 1. What is anatomy? Physiology? What is the difference between function and mechanism? ​ Anatomy is the structure of the body ​ Physiology is the function/mechanism of the body ​ Function: what an organ or tissue does ​ Mechanism: how does that function happen? 2. What are the levels of organization? Name and define each level. 1.​ Chemical Level: a molecule that encloses a cell 2.​ Cellular Level: a cell in the stomach lining 3.​ Tissue Level: tissue in the stomach wall 4.​ Organ Level: an organ which is the stomach 5.​ Body System Level: The body which is the digestive system (Crazy Cats Try On Boots) 3. Name the major organ systems of the human body. List the function and major organs of each. 1.​ Circulatory System: Transports materials between cells in the body -​ Organs: Heart, Blood vessels, Blood 2.​ Digestive System: Converts food to waste -​ Organs: Stomach, pancreas, intestine, liver 3.​ Endocrine System: Coordination of body function through synthesis (produce hormones) and release of regulatory molecules (the hormones) 4.​ Immune System: Defense against foreign invaders -​ Thymus, spleen, lymph nodes 5.​ Integumentary system: Protection from external environment -​ Skin 6.​ Musculoskeletal system (Muscle and Skeleton): Support and Movement -​ Skeletal muscles, bone 7.​ Nervous system: Coordination of body function through electrical signals and release of regulatory molecules (hormones) -Brain, Spinal cord 8.​ Reproductive System: Perpetuation of the species (humans reproduce to ensure our species do not die out) -​ Ovaries, uterus, testes 9.​ Respiratory system: exchange of oxygen and CO2 from internal and external environments -Lungs, airways 10.​Urinary System: Maintenance of water and solutes in body, excrete waste -​ Kidneys, bladder 4. Define homeostasis. What is meant by the internal environment; meaning variables in which fluid have to be maintained when the body is trying to do homeostasis? What does maintenance involve (think input and output)? What is meant by the term relatively stable? What should we not replace that phrase with? What is meant by a dynamic steady state? ​ Maintaining a relatively stable internal environment within an ever-changing environment ​ Internal environment is the conditions the body needs to support life so ECF (extracellular fluid) and ICF (intracellular fluid) must remain stable. ​ Maintenance involves INPUT taking in food, oxygen, heat, etc and OUTPUT excrete waste, CO2 and excess heat, etc. ​ Relatively Stable means This is the set point, fluctuation among a certain level (ex: body temp fluctuates slightly but remains around 37 celsius which is the set point) ​ Do not replace relatively stable with “unchanging” or “constant” ​ Dynamic steady state is the body constantly responding to changes between opposing forces (ex: super cold weather makes your body lose heat, but your body generates heat to maintain temp of body) 5. What is meant by the regulated variable? Give examples? What is the set point? What is normal range? Be able to describe these terms and their relationship? If you were to measure a variable throughout the day, would you always find it to be right at the set point? Explain. ​ A regulated variable is a factor that is actively monitored and maintained like pH or temperature. ​ A set point is the ideal target value at which the variable should be maintained. ​ Normal Range is the range that the variable can fluctuate around while being considered normal. ​ Their relationship is that the set point is within the normal range of function and there are two barriers above and below the set point called normal range. ​ Definitely not, it would remain around the normal range for most of the day, but when working out or having meals, the regulated variable may change and fluctuate. 6. List and define the three components of control systems. Describe the function of each and the relationships between them. Make sure to know the various terms used for each component? What is a stimulus? What’s the effect or response? What are the only effectors in the body? When given an example, you should be able to identify each of these components in the example and understand the role each plays. ​ 1) Receptor 2) Control Center 3) Effector ​ Function: -​ Receptor (Sensor, input signal): monitors environment and responds to stimulus (ex: drop in temp) -​ Control Center (Integrator, Controller): determines the set point, integrates incoming information, and initiates appropriate response -​ Effector (output signal): produces the response to the signal (Ex: shivering muscles) ​ A stimulus is a change in the environment that triggers the control system ​ The effect/response is carried out by the effectors to restore balance to the body (Ex: if body temp rises, effectors will initiate sweating to cool down the body) ​ The only effectors in the body are our muscles (muscle and bones) and glands as muscles give movement and glands do hormone secretion and sweat Extras: The integration center that the receptors send info to is the CNS which has brain and spinal cord. The sensory (afferent) neurons transmit signals from the receptor to the integrating center. These sensory (afferent) neurons are part of the PNS which signals to the CNS. The motor (efferent) neurons commands effectors to respond. So the motor (efferent) neurons carry the response from the CNS to the effectors (muscles or organs) and give them orders such as telling sweat glands to sweat in order to regulate body temperature. 7. What are the two main forms of control? What is meant by each? Give examples. ​ Local Control: Proximal -​ This means that this form of control is close to the site of disturbance. The local control is confined to tissues and organs and the sensors, effectors, and control center are all located near the affected area.. ​ Reflex Control: Distal -​ This means that this form of control is far from the site of disturbance and requires the communication of multiple organs and the CNS for things like baroreceptors or thermoreceptors. 8. Describe the steps in reflex control. What is meant by a feedback loop? What is its function? How does it ensure that the variable will still with its normal range? What are the two types of feedback loops? What is the purpose of each? Contrast both types. Which one is homeostatic? Which one is most common? Give and understand examples of each type. ​ Steps in the reflex control: 1)Stimulus 2) sensor 3) input signal 4) integrating center 5) output signal 6) target 7) response -​ 1) Stimulus: A change in the environment that triggers a response -​ 2) Sensor: specialized receptors or something that detects the stimulus (thermoreceptor or thermometer) -​ 3) Input Signal: The sensor then sends info to the integrating center through afferent pathways which are sensory neurons (sensory neurons from PNS send electrical signals to CNS) -​ 4) Integrating Center: Processes that determine an action on what the body should do. (Hypothalamus tells body to increase body temperature if outside temperature drops) -​ 5) Output Signal: Instructions are sent from integrating center to effectors via effector neurons pathways (motor neurons from CNS send electrical signals to PNS) -​ 6) Target: The tissues or organs that act to correct the disturbance (The muscles) -​ 7) Response: The action taken by the target restores balance (The muscles pulling away from hot stove with the help of bones) ​ A feedback loop is a loop that uses the response to regulate the system and the function is to continue to monitor/adjust the whole system and maintain homeostasis. ​ The variable will still be within normal range because the sensor (Ex: thermoreceptor) will detect the changes from the set point and the integration center will compare the variable to the set point and adjust the output signal accordingly. ​ Two Types of Feedback Loops: -​ Negative Feedback Loop: To stop or reduce changes, restores stimulus by moving it in opposite direction, can increase or decrease a variable, most common, and homeostatic (EX: Super cold weather outside so body shivers and restores our internal temperature) -​ Positive Feedback Loop: Always stimulatory and enhances/amplifies original stimulus, usually increases a variable, and not homeostatic (EX: During childbirth,  baby presses on cervix, and it triggers the contraction to get bigger until baby is born) 9. What happens when there’s a homeostatic imbalance? ​ Diseases like Fever, Hypertension, and Dwarfism 10. What are the two systems that control homeostasis? ​ The Nervous system and Endocrine system -​ Nervous system: Electrical signals are messengers, super fast, travel through sensory nerves -​ Endocrine system: Chemical messengers (hormones), super slow, travel through bloodstream Chapter 2 Molecular Interactions LECTURE: Protein Interactions ​ Passive transport does not require energy ​ No secondary transport without primary transport ​ Active transport uses ENERGY to push up a molecule up to the outside ​ Secondary active transport is cotransport ​ Simple diffusion happens at the kidneys but not the lungs ​ Since the heads of phospholipids are hydrophilic they are also lyophobic meaning they do not mix well with lipids. (vice versa) ​ Hydrophobic (non-polar) molecules can push through the phospholipid bilayer ​ Hydrophilic (polar) molecules must go through the carrier protein ​ A modulator changes proteins ability to bind to ligand or changes proteins ability to create a response ​ Cofactors are needed for ligand to bind at the binding site ​ Proteolytic activation is when removal of part of molecule causes activation ​ Allosteric Modulator binds protein away from active site ​ Covalent modulators are usually irreversible because covalent bonds are stronger than non-covalent.They form a covalent bond with the protein. ​ Up-regulation is the production of new proteins in the human body ​ Removal of proteins is down-regulation ​ Saturation is when all active sites on a given amount of protein are filled with substrate and so the reaction rate is at max. ​ DO not need to worry about dephosphorylation process ​ The 4 protein binding characteristics do not apply to channels ​ Concentration gradient determines if molecule is going up or down Chapter 2: Protein Interactions 1. List and describe the various roles of proteins in the body. ​ 1-6 1)​ Receptor: a receptor that binds to chemical messengers like neurotransmitters and hormones 2)​ Enzyme: breaks down that chemical messenger and terminates its effect  3)​ Channel: A channel protein that is constantly open and allows solutes to pass in and out of the cell 4)​ Gated Channel: A protein that closes and opens to allow solutes (ions like sodium and potassium) through at certain times 5)​ Cell-Identity marker: A glycoprotein that distinguishes between body cells and foreign cells 6)​ Cell-adhesion molecule: A cell-adhesion molecule that binds a cell to another cell 2. What is a binding site? What is a ligand? What is their relationship to each other and to proteins? ​ A binding site is a specific part on a protein where a molecule/ligand can bind ​ A ligand is a molecule that binds to the binding site of a protein 3. Thoroughly explain all the concepts related to the four properties of protein binding and their interaction with each other: specificity, affinity, saturation, and competition. Understand how to apply them. ​ Specificity: The ability for a protein to bind specific ligands (fewer ligands that can bind = greater specificity) ​ Affinity: The strength of attraction between protein and ligand (Highest affinity is ligand is (-) and protein is (+)) ​ Saturation: The number of binding sites that are occupied ​ Competition: When multiple ligands compete for the binding site of a protein (ligand with highest affinity and concentration usually wins) 4. What two factors affect affinity? What two factors affect saturation? How is saturation affected when two proteins can bind the same ligand? ​ The 2 factors that affect affinity are the shape (fit) and charges (how good the shape fits and how opposite the charges are) ​ The 2 factors that affect saturation are Concentration and Affinity (more ligands increase change of binding until all sites are full) (strength of ligand-protein bind) ​ When two proteins can bind the same ligand, saturation is more readily for the protein that has higher affinity 5. What is competition? How does the presence of a competitor affect the rate of reaction? Can two ligands with a similar structure be considered inhibitors of one another? ​ When two or more ligands compete for the same binding site ​ The presence of a competitor affects the rate of reaction by reducing the chances of the preferred ligand to bind therefore slowing down the proteins normal activity. ​ Yes they can be considered inhibitors because they have similar structures therefore being able to occupy a binding site and inhibiting the others position. Chapter 5: Membrane Transport 1. Describe the structure and function of the plasma membrane. ​ Phospholipid Bilayer that has hydrophilic head and hydrophobic tails, also has proteins also known as channels and carbohydrates like glycoproteins and glycolipids 2. Define solution, solvent, and solute. ​ Solution: A homogenous mixture where the solvent dissolves the solute  ​ Solvent: The substance in a solution that has the larger amount and does the dissolving ​ Solute: The substance in a solution that has a smaller amount and gets dissolved 3. Define impermeable, permeable, and semipermeable membranes. Which describes the plasma membrane? ​ Impermeable: no substance can pass through ​ Permeable: any substance can pass through at any time ​ Semipermeable: permits some substances to pass through ​ The plasma membrane is semipermeable because it only allows essential molecules like oxygen, water and nutrients to pass. Phospholipid bilayer restricts large harmful molecules and specific molecules that can pass go through the channels and pumps 4. Distinguish between passive and active transport? List the types of transmembrane movements that are passive and those that are active. Give specific examples for each of the specific types. ​ Passive Transport: Does not require energy ​ Active Transport: requires energy ​ Passive Transport has Simple Diffusion, Facilitated Diffusion, Osmosis, and Filtration (Filtration moves down a pressure gradient while the other 3 move down a concentration gradient) (Filtration is not diffusion) ​ Active Transport has primary and secondary active transport and exocytosis and endocytosis (primary requires atp directly because of sodium potassium pump to move 3 Na out and 2 K in, secondary indirectly requires atp as it uses the sodium gradient made by primary active transport to push potassium into the cell too) (exo and endocytosis always use atp because they need to move large particles in and out of the cell) 5. Define diffusion. What causes it to occur? Describe the different factors that influence the rate of diffusion. Does diffusion require energy? Why or why not? ​ Diffusion is when molecules move from high to low concentration. ​ Diffusion occurs when molecules are in a random motion and there is a difference in concentration (high to low). ​ The different factors are concentration gradient and permeability. ​ Diffusion does not require energy as it goes off of the kinetic energy of the molecules until equilibrium is reached. 6. What do we mean when we say net flux? ​ Net flux is the overall movement of molecules (high to low = positive net flux) (low to high = negative net flux) 7. What is simple diffusion? What determines if a substance can go directly through the membrane and when it requires a channel protein? Give examples of specific molecules that move directly through the membrane and some that use a channel protein. ​ Simple diffusion (not helped) is the movement of solutes down a concentration gradient.  ​ The determination is that it must be a lipid soluble/nonpolar and an exception is water. If it is an ion, it must use a channel protein. ​ Some molecules that move directly through are water, O2, CO2 and some that use channels are K+ Na+ Cl-. 8. What is facilitated diffusion? How is it similar to simple diffusion and how is it different from it? What’s the difference between a channel protein and a carrier protein? Give examples of specific molecules that use facilitated diffusion. ​ Facilitated Diffusion (helped) is the movement of solutes down a concentration gradient with the help of a carrier protein. ​ It is similar to simple diffusion because it does not require energy and goes down the concentration gradient. Difference is that simple diffusion goes directly through the phospholipid bilayer and facilitated diffusion uses carrier proteins to move molecules down the concentration gradient. ​ The difference between a channel protein and carrier protein is that channel proteins are either open or closed. Carrier protein changes shape to transport molecules down concentration gradient. ​ Glucose uses facilitated diffusion because of how big the ion is. 9. What’s meant by mediated transport? Know the three types of carrier-mediated transport. What’s common to all of them and therefore what characteristics are common to their function? ​ Mediated transport is the movement of molecules across the membrane via transport proteins like carrier and channel proteins ​ Facilitated diffusion, primary and secondary active transport ​ They are common because they include carrier or channel proteins. Facilitated diffusion is passive and goes down the gradient and primary active transport requires energy and moves solutes/ions from low to high using sodium potassium pump and secondary uses energy from the sodium concentration gradient that the active transport made. Extra: -​ Channel Proteins: only ions go through, can be open or closed, faster, no binding -​ Carrier Proteins: small polar molecules, always open, slower, yes binding 10. Define primary active transport. Give some examples of materials actively transported across the plasma membrane. Explain the Na+/K+ pump: which ion moves in which direction, and how many of each are moved? ​ Primary active transport is the only type of transport that can have carriers called PUMPS. Directly uses energy to move ions against their concentration gradient using sodium potassium pump. ​ The sodium Potassium pump is an example as Na+ and K+ are going in and out of the cell membrane. ​ 3 Na+ ions move out of the cell and 2 K+ ions move into the cell 11. What is secondary active transport? Is it possible to have secondary active transport that involves only one substance? Give examples of secondary active transport. Is energy needed for secondary active transport? Directly or indirectly? So if a cell were to run out of energy would it be able to do secondary active transport?  ​ Secondary Transport moves substances against their concentration gradient without directly using ATP but rather the energy created from the sodium concentration gradient made from the primary active transport. ​ It is not possible to have secondary active transport with only one substance. Sodium gets pushed into the cell from the sodium gradient and then glucose sneaks in with it. ​ Example would be the sodium-glucose co-transporter (SGLT), sodium moves DOWN its concentration gradient into the cell and glucose moves UP its concentration gradient into the cell from Na+ energy. ​ Energy is needed indirectly because the energy comes from the sodium gradient made from the primary active transport ​ NO, secondary active transport would not be possible because it relies on the ATP used from the primary active transport 12. What is cotransport vs. countertransport? ​ Cotransport (symport): The two substances (ions) cross the membrane in the same direction ​ Countertransport (antiport): The two substances (ions) cross the membrane in opposite directions 13. Define osmosis and osmotic pressure. ​ Osmosis: water moving down its own concentration gradient to equalize solution concentration ​ Osmotic Pressure: Water being forced to move because solutes can’t move through the membrane Extra: In osmosis, water moves from low concentration of solute to high concentration of solute. So from greater water amount to lower amount of water. THE GREATER THE SOLUTE THE GREATER THE PRESSURE 14. Define isotonic, hypertonic, and hypotonic solutions. Define hemolysis and crenation. What happens to RBC when put in each of the following: isotonic, hypertonic, and hypotonic solutions? ​ Isotonic: a solution where the concentration of solute is the same in and out of cell ​ Hypertonic: a solution where there is a higher amount of solute outside the cell than inside ​ Hypotonic: a solution where there is a lower amount of solute outside the cell than inside. ​ Hemolysis: when the cell swells ​ Crenation: when the cell shrinks ​ In Isotonic: cell remains the same ​ In hypertonic: cell with shrink (crenate) ​ In hypotonic: cell with swell (hemolysis) 15. Define filtration and hydrostatic pressure. Where does filtration occur in the human body? ​ Filtration: uses hydrostatic pressure gradient and molecules go from high to low. Substances are forced through with no use of ATP  ​ Hydrostatic pressure: force usually from a liquid like blood that commences the filtration ​ Filtration occurs in the kidneys (specifically glomerulus) and capillaries throughout the body. 16. Define and describe endo- and exocytosis. Which category of transport do they belong to? Why? Are substances moving down or up their concentration gradients? ​ Endocytosis: cell takes in substances into its plasma membrane which then gets pinched off, the thing getting pinched off is called a vesicle, with the use of ATP (phagocytosis - cell eating, pinocytosis - cell drinking) ​ Exocytosis: vesicles of the cell move to the plasma membrane and open up with the use of ATP to release substances. (hormones, neurotransmitters) ​ They both belong to the active transport category because they require ATP no matter the gradient and also to move substances my pinching or opening the vesicle. ​ Endocytosis brings materials into the cell no matter the gradient and exocytosis expels materials out of the cell against its concentration gradient. Ch. 6: Communication 1. What is meant by intercellular communication? What is important? What does it cause? ​ Intercellular Communication is is when cells send, receive, and respond to other cell communications ​ It is important because it allows cells to work together to function tissues, organs, and other systems ​ It causes cells to divide, grow, and secrete substances and change their functions. 2. What are the two basic types of intercellular communication and how does it each happen? What is a target cell? What makes a target? Can one cell be a target cell for more than one chemical messenger? What are receptors and what is their function? ​ The two types of intercellular communication are electrical signals and chemical signals. Electrical signals is when there is a change in the cells membrane electricity (when nerve cells send signals) Chemical Signals is when molecules like hormones or neurotransmitters are secreted into the ECF to communicate with other cells. ​ Target cells are cells that respond to signals ​ What makes a target is if they have a specific receptor for a molecule ​ Yes, a target cell can respond to more than one type of receptor (Ex: liver cells respond to insulin and glucagon.) ​ Receptors are proteins that bind to specific cells or molecules (ligands (hormones/neurotransmitters)) and can be inside or outside the cell membrane. 3. What are the six possible cellular changes in response to signals? 1)​ Alter plasma membrane permeability -​ (allow some ions to pass through) 2)​ Stimulate protein synthesis  -​ (alter gene expression leading to production of specific proteins) 3)​ Activate or deactivate enzyme systems -​ (can stop metabolic processes) 4)​ Induce secretory activity -​ (can secret hormones or enzymes that affect other cells and tissues 5)​ Stimulate mitosis -​ (cell division (mitosis) to repair tissue and growth) 6)​ Induce contractile activity -​ (signals can tell muscle cells to contract) 4. What are the 6 methods of intercellular communication? Describe each, how it happens, what it affects and know appropriate terminology associated with each? Which are considered local? Long-distance? 1)​ Gap Junctions (can be chemical or electrical) -​ Protein channels that allow direct communication between cells because of small cylindrical channels -​ It affects communication as it makes things like muscle contraction super fast -​ The terminology is Connexins -​ It is Local 2)​ Contact-Dependent signals -​ Physical contact by the signal molecule on the cell to the receptor on the other cell -​ It helps in cell communication to control cell growth and immune responses -​ Terminology is CAMs (cell adhesion molecules) -​ It is Local 3)​ Autocrine and Paracrine signals -​ Autocrine: act on same cell that secreted them -​ Regulates cells activity like cell growth and immune responses -​ Terminology is Autocrine signaling -​ It is Local -​ Paracrine: once these are secreted by one cell, they act on a different cell NOT the same one -​ Used for tissue repair for things like inflammation -​ Terminology is Paracrine signaling -​ It is Local 4)​ Hormones -​ Secreted by endocrine cells/glands into the bloodstream to distant cells with the right receptors. -​ Used for growth, metabolism, adrenaline -​ Terminology is hormones -​ It is long-distance 5)​ Neurotransmitters -​ Chemicals released by neurons that diffuse through a small gap into the target cell -​ Used for muscle contraction, dopamine, serotonin  -​ Terminology is neurotransmitters -​ It is Long-distance 6)​ Neurohormones -​ Chemicals released by neurons into the bloodstream to distant target cells -​ Regulate long-term responses to stimuli -​ Terminology is neurohormones -​ It is Long-distance 5. Describe the steps of a signal pathway. Why is the chemical signal called the first messenger? What is considered the second messenger? 1)​ The chemical signal (first messenger) is a ligand that binds to the receptor protein 2)​ Ligand-receptor binding activates the receptor 3)​ The receptor activates one or more intracellular signal molecules 4)​ The last signal molecule modifies existing proteins or initiates synthesis of new proteins 5)​ A response occurs ​ The first chemical signal is called the first messenger because it is the first molecule to bind to the receptor to initiate the whole pathway. ​ A second messenger are those that amplify the signal after the molecule has come in contact with the receptor. 6. Give two possible locations for a receptor, what are they named according to their locations? Where are two possible locations for an intracellular receptor? Which type of messenger utilizes an intracellular receptor? Give specific examples. What types of messengers require a plasma membrane receptor? ​ Intracellular Receptor and Cell Membrane receptor, intracellular is in cytosol or nucleus and cell membrane is on the cell membrane. ​ Hydrophobic messengers utilize the intracellular receptor and diffuse through the cell membrane. ​ Hydrophobic messengers utilize the cell membrane receptor because they cannot pass through the cell membrane. 7. List and describe the four categories of membrane receptors. Which ones involve a signal transduction pathway? Why? 1)​ Receptor-channels: Ligand binding directly opens or closes ion channels. -​ NOT a signal transduction pathway because effect is direct without any signaling 2)​ G protein-coupled receptors: ligand binding activates g protein which leads to changes. -​ A signal transduction pathway that turns a signal outside the cell into a response inside the cell 3)​ Receptor-enzymes: ligand binding activates an enzyme that starts a chain of reactions inside the cell. -​ Converts signal from outside into an internal action 4)​ Integrin receptors: ligand binding affects structure of cell and can cause changes inside. -​ A signal transduction pathway that sends signals outside the cell to make changes inside. 8. What’s a ligand-gated ion channel and how does it work? What’s another name for it? What type of response do they exhibit? ​ A ligand-gated ion channel is the most rapid signal pathway as it opens and closes when a ligand binds. Rapid flow of an ion in or out of the cell causes a rapid response in the cell 9. What is signal transduction? What’s the first messenger? Second messenger? What is meant by the term cascade? What is amplification and why is it important? ​ Signal transduction is when an extracellular signal molecule (first messenger) binds to a receptor and alters secondary messengers to create a response intracellularly. ​ Cascade is when a small signal triggers an enzyme which activates another molecule like a chain reaction, the cascade amplifies the signal at each step ​ Amplification is important because it allows a small initial signal to produce a large cellular signal. 10. What’s a G protein-linked receptor? What type of receptor is it? Why does it involve a signal transduction pathway? Why does it involve a second messenger? What are examples of second messengers? What are examples of actions of second messengers? ​ A G protein-linked receptor is a receptor that activates a g protein when a ligand binds to it. This starts a chain reaction inside the cell called signal transduction. ​ It is a second messenger because the g protein activates molecules inside the cell. ​ It involves a signal transduction pathway because that's how the g protein responds to extracellular signals. ​ It involves a second messenger because thats how the molecules inside the cell will be able to activate. ​ Examples of second messengers would be cAMP, Ca 2+ ​ Examples of actions of second messengers would be to open and close ion channels, activate kinase enzymes, phosphorylate channel proteins, and activate genes and induce protein synthesis. 11. Describe in detail the sequence of events in the signal transduction pathway for cAMP using correct terminology. 1)​ A ligand (signal molecule) binds to a receptor on the cell membrane 2)​ The receptor activates the G-protein inside the cell 3)​ The G-protein turns on adenylyl cyclase which is an enzyme in the cell membrane 4)​ Adenylyl cyclase makes cAMP from ATP 5)​ cAMP activates PKA (protein kinase A) which changes activities of other proteins in the cell 6)​ These changes affect how the cell does certain activities 7)​ Signal ends when enzyme breaks down cAMP 12. Since receptors are proteins, what are the protein-binding characteristics that they exhibit? What are isoforms? How does that impact receptors in terms of the characteristics? What is meant by the terms agonist and antagonist? Which one mimics the ligand? Which blocks its action? Which causes the response? ​ Protein binding characteristics:  1.​ Specificity 2.​ Affinity 3.​ Saturation 4.​ Competitiveness ​ Isoforms are different forms of the receptors ​ This impacts receptors because this could mean they have different properties meaning it changes the way of how they interact with other ligands. ​ Agonist: A substance that mimics the original ligand copying it like the original would ​ Antagonist: A substance that binds to the receptor but doesn't activate it but rather deactivates it. 13. Can one ligand bind to multiple receptors? What can that accomplish? Give an example. ​ Yes one ligand can bind to multiple receptors as it allows a single molecule or ligand to trigger various responses within the body with tissues and cells. ​ Example would be epinephrine as it can bind to alpha and beta-adrenergic to do fight or flight. 14. What’s up-regulation? Down-regulation? What do they enable cells to do? When would each happen, and what would the impact be? ​ Up-regulation is when the cell increases its amount of receptors when there are low amounts of ligands to try to catch all the ligands. (become more sensitive to signal) -​ Impact is that it allows cell to respond effectively when signals are scarce ​ Down-regulation is when the cell decreases its amount of receptors because there are too many ligands and don't want extra responses. -​ Impact is that it protects cell from overstimulation 15. How are signals terminated? Why is termination important? Many diseases and drugs target the proteins of signal transduction: expand on this statement and be able to understand examples (you don’t need to learn any specific examples from the reading). ​ Signals are terminated when enzymes break down the signal molecule, receptors become less responsive/removed, ligand is removed, and proteins are turned off. ​ Termination is important because it prevents overreaction/overstimulation and maintains balance. ​ Many drugs and diseases can block signals, mimic signals, and enhance or reduce activity of proteins. Lecture #3 ​ AT REST, CHEMICALLY sodium IN and Potassium OUT, For ELECTRICALLY, sodium IN and Potassium IN ​ Sodium influx is far greater than sodium eflux Neurons: Ch 8 and 5.7 1. Make sure you have reviewed the anatomy sections and that you are able to integrate all that terminology well. 2. What’s a channel? What type of transport happens through a channel? What’s the only type of substance that passes through channels? What is the difference between a leak and a gated channel? What are the three types of gated channels and what stimulus does each one respond to? ​ A channel is a protein that is embedded in a cell membrane that allows specific substances to pass in and out of the cell. ​ A type of transport that happens through a channel is typically passive as it goes down a concentration gradient without ATP (aka Facilitated Diffusion) ​ The only type of substances that can pass through a channel are ions like sodium, potassium, calcium) ​ Leak channels are always open and allow ions to flow freely across the cell membrane ​ Gated Channels only open or close with the activation of a stimulus (ligand) ​ The three types of gated channels are Voltage, Ligand, and Mechanically-Gated channels. ​ Voltage-gated channels respond to voltages which are caused by the process of action potentials traveling along the cell. ​ Ligand-Gated channels respond to ligands such as a neurotransmitter. ​ Mechanically-gated channels respond to deformation within the cell membrane Mechanical Stress = (stretching, pressure) 3. What is meant by “electrical disequilibrium” across the cell membrane? What causes it? Where is this disequilibrium only true (all over the ICF and ECF or just immediately on the inside and outside of the plasma membrane?? ​ Electrical Disequilibrium across the cell membrane refers to the unequal amount of charged ions in the ECF and ICF. ​ What causes it is ion concentration gradients like how there are more sodium ions extracellularly and more potassium ions intracellularly. Active transport as well like the sodium potassium pump. Selective permeability too as the membrane is more permeable to K+ letting more of those ions through. ​ Disequilibrium is only true immediately on the inside and outside of the plasma membrane. 4. Describe the distribution of Na+ and K+ inside and outside the cell. At rest, which of these two ions is the membrane more permeable for? What type of channels are these ions going through at rest? ​ Na+ is 145 extracellularly and 15 Intracellularly ​ K+ is 5 extracellularly and 150 Intracellularly ​ At rest, the membrane is more permeable for potassium ions. ​ The type of channels these ions are going through at rest are leak channels because these channels contribute to the resting membrane potential. 5. What’s meant by the term “potential”? Describe the basis of the resting membrane potential, meaning what causes there to be difference of charge inside versus outside the cell (2 things)? What is the RMP for most neurons? What is meant by that number? How is the RMP maintained? ​ Potential refers to electrical voltage difference across a cell membrane  ​ Resting membrane potential is the electrical potential created by living cells due to uneven distribution of ions between ICF and ECF. The sodium potassium pump causes the difference of charges inside and outside the cell. ​ The RMP for most neurons is -70mV ​ What is meant by that number is that there is 70 less intracellularly than extracellularly. ​ RMP is maintained by Ion electrochemical gradients, permeabilities, and sodium potassium + ATPase pump. 6. Where does the chemical and electrical gradient of Na+ and K+ pull each one? Define electrochemical gradient. Based on each ion's electrochemical gradient, does the ion have net influx or net efflux through a channel? What’s the equilibrium potential of Na+ and K+? Based on these equilibrium potentials, which way will Na move when its gated channels open, what about K? Also, which ion has an equilibrium potential further away from RMP? What does that mean in terms of the driving force on each of these ions to move across the membrane; meaning when a gated channel opens for both of these ions, which ion will rush across the membrane in much greater amounts? ​ Sodium is IN IN and Potassium is IN OUT (chemical gradient). ​ An electrochemical gradient is just all the chemical and electrical forces acting together across the membrane. ​ Sodium has net influx and Potassium has a net efflux through the channel. ​ The equilibrium potential of Na+ is +60mV and Potassium is -90mV ​ Na will move in the cell as it goes from more positive from outside to the inside. K will rush out of the cell because there's much more K inside than outside. ​ Na+ has an equilibrium potential further from RMP because it is +60. ​ Na+ will rush across the membrane in much greater amounts because during resting, there are less sodium channels opened. 7. Why is a cell called polarized? Define depolarization, repolarization, hyperpolarization, overshoot. ​ A cell is polarized when the electrical charge is different from the extracellular membrane to the Intracellular membrane. ​ Repolarization is when the membrane potential goes back to its original stage after depolarization ​ Hyperpolarization is when membrane potential becomes more negative than resting potential ​ Depolarization is when membrane potential becomes more positive than resting potential. ​ Overshoot is when it goes past 0mV due to the influx of more sodium ions. 8. What do neurons use electrical signals for? How are these signals produced (generally)? What are the two types of electrical signals? Where on the neuron does each one occur? Which type of channel does each one involve? Which one causes the other one and what's the condition under which it would cause it? What is the trigger zone and where is it? ​ Neurons use electrical signals to integrate, send, and receive information. ​ These signals are produced by changes in the membrane permeability for ions and alternation of ion concentration across the membrane.  ​ The 2 types of electrical signals are graded potentials and action potentials. ​ Graded potentials occur on the dendrites and cell body and Action potentials occur on the trigger zone of axons ​ Graded potentials involve Mechanical, chemical, and voltage-gated channels while Action potential only has voltage-gated channels. ​ Graded potentials cause action potentials, the condition is that the mV reaches -55mV. ​ The trigger zone is where action potentials are created. It is located on the axon hillock. 9. Know and understand all the differences between graded and action potentials. ​ Graded Potential -​ Input signal -​ Occurs in dendrite and cell body -​ Mechanical, chemical, or voltage-gated channels -​ Ions involved are Na+, Ca2+, and K+ -​ Type of signal is depolarizing or hyperpolarizing -​ Strength of signal depends on Initial stimulus, can be summed -​ Entry of ions through gated channels initiates the signal -​ Unique characteristics: no minimum level of requirement to initiate, 2 signals coming close together in time can sum, initial stimulus strength is indicated by the frequency of a series of action potential. ​ Action Potential -​ Regenerating conduction signal -​ Occurs at trigger zone through an axon -​ Types of gated-channels are voltage-gated -​ Ions involved are Na+ and K+ -​ Type of signal is depolarizing -​ Strength of signal is all-or-none and cannot be summed -​ Above-threshold graded potential at trigger zone opens ion channel and initiates signal -​ Unique Characteristics: Threshold is required to initiate and refractory period is two signals too close together in time cannot sum. 10. When is a graded potential called excitatory? Inhibitory? What is meant by each term? ​ Graded potential is excitatory when all or none is most likely to happen. Inhibitory is when there's a harder chase to hit that -55mV for action potential to occur. 11. Does the size of the graded potential vary with the strength of the stimulus? How does a stronger stimulus cause a bigger GP? What is meant by the size of a potential? Can you have a bigger inhibitory GP? Does the size of the AP vary with the strength of the stimulus? ​ The bigger the size of the graded potential the greater the strength of the stimulus. ​ A stronger stimulus causes a bigger graded potential because graded potentials are not all or nothing meaning the bigger frequency and open more ion channels while action potentials are all or nothing mean, frequency wont change the amount of ion channels that open. 12. What does decremental mean? Which of the two signals is decremental and which is not? What are the implications of that? ​ Decremental is a decrease in intensity with distance ​ Graded potentials are decremental and Action potentials are non-decremental ​ Graded potentials because the signals weaken over time but Action potentials are all or none meaning the signals stay the same 13. Which of the two signals requires a threshold-stimulus? What is meant by that term? ​ Action potential requires a threshold-stimulus ​ Threshold-stimulus is the minimum amount of “push” or “signal” needed for the action potential to occur. 14. What is meant by action potentials are all-or-none events? What about them makes you know that they are all- or-none? What causes them to be all-or-none? ​ All or none just means that action potentials either happen fully or don't happen at all. We know it's all or none because if the graded potential does not make neuron reach -55mV, the action potential will not activate at all. Also, once the action potential is released, a sodium channel is opened which opens all the other ones. 15. Describe the action potential and explain what causes depolarization, repolarization, and hyperpolarization. What type of channels are responsible for these phases? Describe the properties of all channels involved in the AP. What ions are moving and in which direction in each of the phases? What happens at the peak of the AP? How are VG-K channels described? What’s that responsible for? How’s the membrane returned to the RMP after the AP is over? Why does the AP require energy? ​ Action potential is a signal that travels across the membrane of a neuron allowing communication along long distances for the opening and closing of channels. ​ The things that cause depolarization Na+ rushes into the cell changing the voltage from -55mV to +30mV ​ The things that cause repolarization are the Na+ channels deactivate and the K+ channels activate bringing the voltage from +30mV down to -70mV, the resting membrane potential. ​ Hyperpolarization is when the K+ channels remain open and can shoot down to -90mV. ​ The types of channels responsible are voltage-gated sodium channels for depolarization, voltage-gated potassium channels for repolarization, and voltage-gated potassium channels for hyperpolarization. ​ The properties are that the voltage-gated sodium channels let Na+ ions rush inside, and voltage-gated potassium channels allow K+ to rush outside. ​ Na+ is moving out, K+ is moving in. ​ At the peak of action potential, sodium channels deactivate, and potassium channels activate therefore starting the process of repolarization. ​ Voltage-gated potassium channels are described as slow opening channels during depolarization and since they close slowly, they cause an undershoot over the resting membrane potential.  ​ The membrane returns to RMP after AP is over when the closing of voltage-gated potassium channels and the help of sodium potassium pump to help bring the concentration gradient to its original state which is RMP -70mV. ​ AP requires energy because without energy, the action potential can't activate the sodium potassium pumps. 17. What type of gated-channel is responsible for helping the membrane reach a threshold? When you have a supra-threshold stimulus, do you get a “bigger” action potential? So how do we code for the strength of stimulus? ​ The types of gated-channels are ligand-gated channels. ​ No you don’t, this is because action potentials are all or nothing so size of AP stays the same no matter the stimulus strength ​ Stimulus strength is encoded by the frequency and not the size. 18. Define refractory period and distinguish between absolute refractory period and relative refractory period. What is the significance of the refractory period? How is it related to one-way propagation? How is it related to coding for stimulus strength? ​ Refractory period is the time when a neuron is unable to generate another action potential. ​ Absolute refractory period is when no action potential can be generated no matter how strong the stimulus is. ​ Relative refractory period is when a second action potential can be generated, but the stimulus has to be stronger than usual. ​ A significance of refractory periods is that it prevents the overlapping of action potentials. ​ Prevents the backflow of AP (one-way propagation). ​ Stimulus strength is encoded by the rate of fire not by the size of the action potential. 19. What is meant by conduction of the AP? Describe how the action potential is propagated (conducted) in an unmyelinated neuron. What makes the conduction go in the right direction only (one way)? What is the right direction? What does saltatory conduction mean? In which types of neurons does it occur? Describe how it happens and why is it important? ​ What is meant by the conduction of AP is how the electrical signals travel down the axon of a neuron ​ In unmyelinated neurons, action potentials are conducted continuously along the axon ​ The refractory period makes the conduction only go in one way so action potential does not backflow. ​ The right direction is the action potential moves to the axon hillock then to the axon terminals which is where neurotransmitters are released. ​ Saltatory conduction is when action potentials jump between the nodes of ranvier. ​ Occurs only in myelinated neurons ​ Saltatory prevents ion flow in the myelinated areas which therefore reduces of the workload of the sodium potassium pump because there are few ions flowing across membrane and since AP is jumping in between the nodes, action potential is delivered from axon hillock to axon terminal quicker. 20. What are the two factors that influence the speed of action potential conduction? How does each one impact the speed and why does it have that impact? What happens in multiple sclerosis? ​ Two factors that influence the speed of action potential conduction is the diameter of the axon and the myelination of the axon. ​ Larger diameter = faster conduction because there is less resistance on ion flow ​ Myelination = faster conduction because it “jumps” from each node, skipping myelinated sections ​ MS is a disease that attacks the myelin sheath of neurons therefore giving slower conduction or even failure of action potentials eventually leading to muscle weakness, vision problems, etc. 21. What are the two types of synapses? Which one is more common? ​ Electrical synapses and chemical synapses ​ Chemical synapses are more common 22. Describe the mechanism that causes the release of neurotransmitters at the synapse? What does the neurotransmitter cause to occur on the postsynaptic membrane? ​ First, action potential depolarizes the axon terminal and arrives at it, Second, the depolarization opens the calcium voltage-gated channels and Ca2+ enters the cell, third, calcium entry triggers exocytosis of synaptic vesicle content (neurotransmitters inside), Fourth, neurotransmitters diffuse across the synaptic cleft (empty space in between) and binds to the receptors on the postsynaptic cell. Fifth, neurotransmitter binding initiates a response in a postsynaptic cell. ​ After the neurotransmitters bind to the receptors on the postsynaptic cell, ligand-gated ion channels open and sodium rushes into the postsynaptic cell which causes EPSP (small depolarization). 23. What is an EPSP? What type of potential is it (graded or action)? What is an IPSP? What type of potential is it? ​ An EPSP is a small depolarization of the postsynaptic membrane with the influx of positive sodium ions. ​ It is a graded potential ​ An IPSP is a small hyperpolarization of the postsynaptic membrane with the influx of negative ions like chlorine or efflux of positive ions. ​ It is a graded potential for both EPSP AND IPSP because they use ligand-gated ion channels rather than voltage-gated ion channels. Ligand channels don’t reopen and dont regenerate the signal like action potentials. 24. Describe how the strength of stimulus affects the graded potential and the action potential? Does it change their size? Does it change their frequency? What does it have different impacts on a GP vs. an AP? How does the strength of the stimulus impact the amount of neurotransmitter released? How does that impact the postsynaptic neuron? ​ Strength of stimulus the stronger it is will open more ligand-gated channels for graded potential for more Na or K to flow in and out. Strength of stimulus that stronger it is for action potential does not change the size of action potentials, they are all the same  ​ For graded potentials, the stronger stimulus will allow for a larger graded potential. For action potential, the stronger stimulus will do nothing and the size of an AP will stay the same. ​ Graded potentials do not have a frequency and the stronger the stimulus for action potentials, the higher the firing rate (more frequent AP) ​ Different impacts are that for GP, stimulus strength affects size directly while for AP, size isn't affected but rather frequency (rate of firing) ​ A stronger stimulus for AP increases the frequency meaning more Ca2+ influx will release into the postsynaptic cleft. ​ More neurotransmitters generate larger EPSPs or IPSPs in the postsynaptic neuron. 25. What are the different mechanisms of neurotransmitter termination at the synapse? ​ The different mechanisms of neurotransmitter termination at the synapse is that the neurotransmitters is taken back by the presynaptic neuron AND enzymes in the synaptic cleft break down the neurotransmitter making it inactive AND the neurotransmitters just diffuse into nowhere in the synaptic cleft. 26. What divergence? Convergence? Why are they important? ​ Divergence is when one presynaptic neuron splits into many postsynaptic neurons. ​ It is important because it allows the neuron to activate multiple targets, like a motor neuron activating many muscles ​ Convergent is when many presynaptic neurons give info/input to a smaller amount of postsynaptic neurons. ​ It is important because it obtains multiple information from multiple inputs to determine output. 27. What is meant by summation? Why is it important? Describe the two types of summation, explain how each happens, and distinguish between them. Do EPSPs and IPSPs summate? ​ Summation refers to the process in which graded potentials (IPSP and EPSP) work together to determine if a neuron will reach a threshold and generate an action potential. ​ It is important because summation allows for the integration of IPSP and EPSP signals to make decisions on whether or not to fire an action potential. ​ Temporal Summation: occurs when one presynaptic neuron send multiple signals on its own (like one person cheering you on continuously) to the synapse RAPID FIRE BUT NOT AT THE SAME TIME ​ Spatial Summation: occurs when many presynaptic cells send signals to the synapse AT THE SAME TIME ​ Yes they do summate to determine if action potentials get fired. More ESPS = higher chance of action potential MORE ISPS = less chance of action potential Central Nervous System: Ch 9.6 (only selected portions, just make sure you are able to answer the questions below) 1. What are the three functional areas of the brain? What is each one responsible for? ​ Sensory area: sensory/perception/awareness ​ Motor Area: skeletal muscle movement  ​ Association Area: Integrate info from sensory and motor areas, can direct voluntary movement 2. What is meant by cerebral lateralization? What are the “specialties” of each hemisphere? ​ Cerebral lateralization is how the left and right hemispheres do different things. ​ Right hemisphere: creativity, emotions ​ Left hemisphere: writing, speaking 3. What’s the definition and the function of sleep? What are the two major sleep phases? What are the major characteristics of each phase? ​ Sleep: state of rest where the body can recover and the function is to restore energy and repair the body ​ Slow-wave sleep: high amp, low frequency, sleeper adjusts body without brain command ​ Rapid-eye movement (REM) sleep: low amp, high frequency more similar to awake person, brain paralyzes motor neurons and skeletal muscles and dreaming takes place, decline in body temperature 4. Define learning. What is associative learning? Nonassociative learning? What are the two types of nonassociative learning? ​ Learning: acquiring knowledge ​ Associative learning: combination of 2 stimuli working together (after getting hit by a knife two times, i am scared of it) ​ Non-associative learning: change in behavior after being exposed to stimulus too much (I Get used to loud knocking doors after a while because i what it so much) ​ Two types are: Habituation (getting used to something) and Sensitization ( enhanced response due to exposure, me getting scare of knocking doors) 5. Define memory. What’s short-term memory? Long-term memory? What’s the name of the process by which short is transferred to long? How is that done? What’s working memory? ​ Memory: The ability to store, retain and receive information ​ Short-term memory is holding onto info for a short amount of time (2-7 items) ​ Long-term memory is holding onto an infinite amount of info for a long time ​ Consolidation is short transferred to long ​ It is done by rehearsal, sleep ​ Working memory is short term but in the moment so like how to deal with a stressful situation 6. What are the two specific brain areas involved in speech control? Where is each area found in the brain? What is the specific role for each of the areas? What is receptive aphasia? Expressive aphasia? ​ Wernicke's area: understanding language (left temporal lobe) - receptive aphasia ​ Broca’s area: produce speech (left frontal lobe) - expressive aphasia ​ Receptive aphasia: trouble understanding ​ Expressive aphasia: trouble producing speech LAST LECTURE: ​ Sodium channels only have 2 gates which are activation and inactivation while Potassium has only one gate which is activation. ​ Sodium potassium pumps restore potassium back to rest because it does not have an inactivation gate. ​ Absolute refractory period is a period in which your stimulus is unresponsive to stimulation. ​ A stronger stimulus during the relative refractory period allows for a quicker fire for a faster response. This does not shorten the time of the relative refractory itself period but allows for the firing of the neuron to be quicker. ​ Propagation: conduction of a current all along the axon ​ Absolute Refractory period blocks backflow of sodium ions during one way propagation. ​ In saltatory conduction, action potentials jump from one node of ranvier to another along the axon ​ Continuous conduction is for unmyelinated