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Physiology Exam 1
Includes intro to physiology through endocrine system
| Term | Definition |
|---|---|
| Physiology | Study of the functions and processes of living organisms |
| Organization of physiology | Organ systems --> Organs --> Tissues --> Cells |
| Function vs process (mechanism) | Function explains the 'why' = teleological approach Process or mechanism explains the 'how' = mechanistic approach |
| Compartmentation | Divisions of body, within a cell. Ex: organelles, systems, lumen |
| Compartmentation advantages and disadvantages | Advantages: metabolic processes, concentrate, enzymes/chemicals Disadvantages: Transport and availability |
| Energy transfer | Life is work --> maintaining homeostasis |
| Energy: Biological systems | Animals and plants intake food to import energy Kinetic and potential |
| Respiration (cellular) | extracts energy to do WORK |
| Transport Work | moving ions, molecules, and larger particles. Ex: Concentration gradients |
| Mechanical Work | Muscle movements. Ex: curling a dumbbell |
| Chemical Work | Making bonds of breading chemical bonds. Ex: Growth, storage of information |
| Homeostasis = "similar conditions" | External or internal change physiological attempt to correct Loss of homeostasis |
| Regulatory control systems | Feedback: Positive or Negative Feedforward: anticipation |
| Homeostasis - basic pathway | sensor --> integrator --> effector <<<------------------------------------ |
| Control mechanisms | Variable, Receptor, control center (integrator), effector |
| Variable | Regulated feature of internal environment Ex: Blood pressure, blood temp, blood glucose, breathing rate |
| Receptor | Sensitive to change, Serves as a monitor of variable and sends information to control center Ex: Temp sensing, sugar sensitive proteins, pain sensors |
| Control center | Determines a set value for the variable. will act or adjust accordingly based on information received from the receptor Ex: Nervous, endocrine system |
| Effector | Receives information from control center and produces a response Ex: Organ or gland |
| Negative feedback | Response reverses original stimulus Most common type Maintains variable in narrow range Ex: Body temp, blood pressure, blood glucose levels |
| Positive feedback | Response enhances original stimulus Rare Provokes rapid change in variable Ex: Clotting cascade, Childbirth, Action potentials |
| Polar | water, non-lipid based |
| Non polar | oil, lipid based |
| Cell membrane transport: physical requirements | molecular size solubility in lipids ionic charge |
| Cell membrane transport: energy requirement | concentration gradient ATP (direct or indirect) |
| Channel proteins | create a water-filled pore (diagram) |
| Carrier proteins | Never form an open channel between the two sides of the membrane (diagram) |
| Membrane transport | Passive = no ATP Active = ATP required |
| Passive transport | simple diffusion Osmosis (in special cases) Facilitated diffusion |
| Simple diffusion | High --> low concentration (beaker example) |
| Facilitated diffusion | diffusion through transport proteins in the plasma membrane |
| Active transport | USES ENERGY (ATP) Primary and secondary |
| Primary active transport | ATP binds to carrier Energy used to move molecule |
| Secondary Active transport | uses concentration gradient ATP is used to expand gradient |
| 3 forms of energy stored in the body | chemical bonds concentration gradients electrical gradients |
| why do cells communicate? | Maintaining homeostasis requires communication Must have integration from different components: Local, Long distance, Chemical, Electrical |
| Electrical signaling | resting membrane potential (RMP) --> basis for electrical signals changes in membrane potential --> changes in membrane permeability ex: muscles and nerves |
| Chemical signaling | Ligand --> receptor interactions |
| Membrane potential | ALL CELLS HAVE A MEMBRANE POTENTIAL Secretion of neurotransmitters and hormones |
| Potential energy | chemical bonds, concentration gradient, electrical gradients |
| Extracellular fluid | Fluid found it the space around cells, comes from substances from blood in capillaries |
| Intercellular fluid | Fluid found inside cells |
| Diffusional (Chemical) forces | Ions are subject to both diffusional (chemical) and electrical forces Diffusional (chemical) forces |
| Electrical (electrostatic) forces | Electrical forces (charge of ions) |
| Net electrochemical force and equilibrium potentials | When the chemical force is equal in magnitude but opposite in direction as the electrical force Refer to the diagram on page 15 of notes |
| Equilibrium potential for potassium (K) | -90mV |
| Equilibrium potential for sodium (Na) | +60mV |
| Why is the equilibrium potential for Na+ a positive number while that of K+ is a negative number if both ions are cations | Because their chemical gradients are in opposite directions We would need our electrical gradient to counteract our chemical gradient |
| Create electrical communication | Change membrane potential Create action potentials Release neurotransmitters |
| Changing resting membrane potential or ion permeabilities | Leak channels Gated channels |
| Leak channels | Keep resting potential |
| Gated channels | Chemical, Voltage, Mechanical Ex: action potentials |
| Chemically gated channels | Ligand, messengers |
| Voltage gated channels | Responds to changes in membrane potential plays a significant role in electrical signal conduction |
| Mechanically gated channels | opens in response to pressure from physical forces |
| Change in ions are NOT due to bulk flow | maintains [ ] gradient Na+/K+ pump |
| Resting membrane potential | naturally occurring charge difference between in the inside and outside of cell The state when the cell is not stimulated Measured in mV = average = -70mV |
| Chemical signaling | Ligand: hormone, chemical, neurotransmitters Receptor: inside cell, membrane bound |
| Signal transduction | Process by which cell converts one kind of signal or stimulus to another Different possibilities, depends on the receptor |
| Cell communication | Local: gap junctions, juxtacrine, autocrine, paracrine long distance |
| Gap junctions | direct and local cell-to-cell communication for direct cytoplasmic connections between adjacent cells transfer both chemical and electrical signals |
| Juxtacrine (contact-dependent signals) | Direct contact and local cell-to-cell communication Require interaction between membrane molecules on two cells CAMs transfer signals in both directions |
| Autocrine signals | Act on the same cell that secreted them |
| Paracrine signals | are secreted by one cell and diffuse to adjacent cells |
| Hormones | are secreted by ENDOCRINE glands or cells into the blood. Only target cells with receptors for the hormone will respond to the signal |
| Neurocrine signaling (neurohormones) | are chemicals released by NEURONS into the blood for action at distant targets |
| What determines cellular response? | Receptor specificity Type of internal signal --> mediated by second messengers |
| Types of receptors | Metabotropic and Ionotropic |
| Second messengers | Ions: Ca2+ Nucleotides: cAMP and cGMP Lipid derived: IP3 and DAG |
| Signal Pathway: Receptor Enzymes | Receptor = enzymes 2 regions: Receptor region and enzyme region Enzyme region: protein kinase and guanylyl cyclase Ligand binding activates enzyme |
| Insulin activity | 1. insulin binds to tyrosine kinase receptor 2. receptor phosphorylates insulin-receptor substrates (IRS) 3. second messenger pathways alter protein synthesis and existing proteins 4. Membrane transport is modifed 5. Cell metabolism is changed |
| GPCR: Adenylyl cyclase-cAMP | 1. signal molecule binds to G-protein-linked receptor, which activates the G protein 2. G protein turns on Adenylyl cyclase, an amplifer enzyme 3. Adenylyl cyclase converts ATP to cyclic AMP 4. cAMP activates protein kinase A |
| GPCR: Adenylyl cyclase-cAMP (cont) | 5. protein kinase A phosphorylates other proteins, leading ultimately to cellular response |
| G protein coupled receptors | Open/close ion channels Alter enzyme activity Alter gene expression |
| Electrical and chemical together | some second messengers create electrical signals |
| Signal Pathway: Receptor-Channel | 1. Receptor-Channels open or close in response to signal molecule binding 2. Some channels are directly linked to G proteins 3. Other ligand-gated channels respond to intracellular second messengers |
| Terminating the signal | stop simulation of receptor removal of ligand: degradation, reuptake, stop release |
| Alpha adrenergic receptor | Vasoconstriction |
| Beta adrenergic receptor | Vasodilation |
| Specificity | the selectivity to what they can bind to 'lock and key' |
| Protein interactions – molecular complementarity | binding site, ligand, affinity |
| protein interactions | Competition for binding sites - agonist/antagonist - endogenous/exogenous - reversible/irrversible |
| Regulation - prosthetic group | Permanently bound organic or ionic |
| Regulation - coenzyme | binds loosely and reversibly consumed and recycled non protein, organic ADP, ATP, Coenzyme A |
| Competitive inhibition | a competitive inhibitor blocks ligand binding at the binding site |
| Allosteric Modulation | ACTIVATION: protein is inactive without modulator INHIBITION: protein is active without modulator Opposite side of binding site |
| Protein interactions | Up-regulation and down-regulation |
| Up-regulation | as time passes, more binding sites are present |
| Down-regulation | as time passes, less binding sites are present |
| Physical regulators | Temperature and pH Causes proteins to denature |
| Control systems: Tonic control | regulated physiological parameters in an up-down fashion |
| Control Systems: Antagonistic Control | Antagonistic neurons control heart rate; speeding up or slowing down |
| Endocrine system | Releases hormones and regulates body processes in the glands, tissues, and cells |
| Hormones: Function | @ cellular level - transports ions across cell membrane - gene expression or protein synthesis Performs at low concentrations Binds to target cell receptors |
| Hormones: Classification | Peptide or protein Steroid Amino acid |
| Peptide or protein hormones | Majority of hormones Size variability LipoPHOBIC ex: insulin Uses cAMP Preprohormone Prohormone |
| Preprohormone | Signal sequence --> direct to the ER Copies of peptide hormones Loses signal sequence |
| Prohormone | packed into Golgi break apart inactive prohormones into active hormones and fragments |
| Hormone: release | hormone and pieces stay in vesicle until release signal is received. Once received vesicles can move into the membrane |
| Travel - peptide | upon release the hormone is released into the blood travels and spreads reaches target organ |
| Peptide Hormone-Receptor Complex | Surface receptor Hormone binds: enzyme activation, open channels, cellular response |
| Steroid Hormones | Cholesterol derived --> lipoPHILIC and can enter target cell Cytoplasmic or nuclear receptors (mostly) Activated DNA for protein synthesis Longer half-life Ex: cortisol, estrogen, testosterone |
| Steroid Hormones | needs to have a receptor |
| Amine Hormones | derived from one or two amino acids Tyrosine based |
| Tyrosine based | Thyroid hormones T3 and T4 Catecholamines: Dopamine --> Norepinephrine --> Epinephrine |
| Hormone interactions | Synergism: multiple stimuli Permissiveness: needs second hormones to get full expression - Thyroid + reproductive hormones Anatagonism: Opposing |
| Synergism | Exercise is seen in this Raises blood glucose levels Release more than one can have a higher effect Not addictive |
| Simple Endocrine Reflex: Parathyroid Hormone | Direct sensation and release of hormone by a particular cell |
| Endocrine reflex pathways | stimulus afferent signal integration efferent signal Physiological action Negative feedback (sometimes feedforward) |
| Negative feedback controls | long loop feedback (2) short loop feedback (1) |
| The Pituitary Gland Anatomy | Anterior pituitary (glandular tissue) Posterior pituitary (neural tissue) |
| Posterior pituitary gland | Neuro hormones: Vasopressin, Oxytocin Vesicles containing neurohormones are produced in the cell body Traveled along microtubles by molecular motors Secretion Ca2+ facilitates exocytosis and causes an action potential |
| Endocrine axes | Three levels of control represent an axis: Hypothalamus, Anterior Pituitary, Endocrine gland Hypothalamo-pituitary-adrenal Hypothalamo-pituitary-gonadal |
| Hypothalamus | stimulation from CNS |
| Anterior pituitary | stimulation from hypothalamic releasing hormones |
| endocrine gland | Stimulation from pituitary trophic hormones |
| The Hypothalamic-Hypophyseal Portal System | Two capillary beds arranged one after another --> no route back to the heart Hormones released by the hypothalamus will go directly to anterior pituitary need only small amount for response |
| adrenal gland | A small gland that makes steroid hormones, adrenaline, and noradrenaline. These hormones help control heart rate, blood pressure |
| issues: Growth hormone | dwarfism gigantism --> children acromegaly --> adults |
| HPT | Grave's disease Goiter |
| Endocrine pathologies | Hypersecretion and Hyposecretion |
| Hypersecretion | excess hormone; tumors or cancer - Grave's disease - thyroxin |
| Hyposecretion | deficient hormone Goiter - thyroxin Diabetes - insulin |
| Grave's disease | Autoimmune disease Produces antibody that recognizes receptor for thyroid stimulating hormone Activates receptor --> over produces thyroid hormone |
| Goiter | Iodine deficiency Hypertrophy: overgrowth in attempt to produce enough thyroid hormone Tumor producing thyroid stimulating hormone |
Created by:
mcb373
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