E109 Lecture 1: Welcome+Osmolarity, Tonicity, Diffusion PDF

E109 Lecture 1: Welcome+Osmolarity, Tonicity, Diffusion Learning Goals Review the syllabus, understand class logistics No “content questions” via email. Use Ed Discussion Individual office hours OK Larc Tutor: Anushka Singh [email protected] Bio Sci Peer Tutors: Gracey Singh [email protected]...

E109 Lecture 1: Welcome+Osmolarity, Tonicity, Diffusion Learning Goals Review the syllabus, understand class logistics No “content questions” via email. Use Ed Discussion Individual office hours OK Larc Tutor: Anushka Singh [email protected] Bio Sci Peer Tutors: Gracey Singh [email protected] Alireza Oladaskari [email protected] Understand generally what “physiology” means Learn the difference between osmolarity and tonicity Observe how diffusion works Learn the basics of “Fick’s Law” Understand that there are different types of membrane proteins: some transport ions or molecules, some transmit signals to the cellular environment E109 Lecture 1: Welcome+Osmolarity, Tonicity, Diffusion Human Physiology Human Physiology: The science of the mechanical, physical, and biochemical functions of our bodies Physiology is studied at various levels of organization Important Concept in Physiology: Homeostasis ftp.ffioantiiay around a set point in hot a if workout sweatingafter How to maintain homeostasis Cells contain intracellular fluid (ICF) The cell External membrane Cells ECF environment separates cells from ECF Cells are surrounded by ECF Fluid compartments KEY Intracellular fluid Interstitial fluid Plasma Interstitial Intracellular fluid fluid extra ECF ICF 1/3 2/3 Cell membrane In Maintaining Disequilibrium 160 140 KEY Ion concentration (mmol/L) 0 120 Na K 100 Cl 80 HCO3 Proteins 60 40 20 Intracellular fluid Interstitial fluid Plasma Extracellular Fluid a there is much less k extracellularly thereis much more K  y E109 Lecture 1: Welcome+Osmolarity, Tonicity, Diffusion Osmolarity Number of solute particles per volume A B A B Selectively permeable membrane Less solutes means there is more water osmosis will move water to where there is more solutes to reachequilibrio Osmosis: movement of water across a membrane mum Tonicity MI ions in solution relative to the cell Place Red Blood Cells in solutions with different amounts of solutes Less More solutes solutes 1 iswelling bursts to more solutes on the outside of the cell water is moving water is moving solutes out where the shriveling are bursting Calculating Osmolarity ECF ICF S/V= C extracellularfluid intercellularfluid S= #solutes (mOsm) 300 mOsm/L 300 mOsm/L V= Volume (L) C= solute conc. (mOsm/L) 300 mOsm 600 mOsm S= C x V 1L 2L SECF= 300 mOsm/L x 1L SECF= 300 mOsm in terms of osmolarity FFG ICF must stay in equilibrium to avoid hypotonicity hypertonicity What would happen if you doubled the volume of ECF without changing the number of solutes? it would becomehypotonicrelative to the intercellular fluid dilutedtheECF solutes will try to travel out of the cell to exploding cells  g y Diffusion smaller things diffuse faster Congoredis a much largermolecule KI Congo red Dyes placed in wells of Diffusion of dyes agar plate at time 0 90 minutes later Fick’s law of diffusion If sets upexpectations of howquickly Extracellular fluid things can diffuse Molecular across a Membrane surface area Lipid size Concentration outside cell membrane solubility Factors affecting rate of diffusion through a cell membrane: Lipid solubility Molecular size Concentration Concentration gradient gradient Membrane surface area Composition Composition of lipid layer of lipid layer Intracellular fluid Concentration inside cell Fick’s Law of Diffusion Membrane Permeability Membrane lipid solubility permeability  molecular size Rdiffusion  surface area  conc. gradient  memb. permeability more likely Img ngsare Changing the composition of the lipid layer can increase or decrease membrane permeability. Review Osmolarity- the number of solutes present in a unit volume of fluid. Differences in osmolarity can drive movement of fluids or develop osmotic pressure Tonicity- A physiological feature of a fluid that determines whether fluid will move into or out of cell Diffusion- movement of molecules from an area of high concentration to an area of low concentration. Diffusion across the cell membrane depends on the size of molecules and membrane permeability E109: Membrane Transport & Communication Membrane Proteins Structural proteins communication Enzymes /signaling Membrane receptor proteins Transporters transport – Channel proteins – Carrier proteins E109: Membrane Transport & Communication Learning Goals Finish discussing membrane proteins. Understand symporters, and discuss signal transduction impacting intracellular function. Understand homeostatic control loops To review cellular communication (short & long distance) To understand the classification, structure, and synthesis of hormones To understand hormone interactions To understand the pathways of endocrine regulation Membrane Transporters Facilitated diffusion Equilibrium Conversion can be maintains reached gradient High glucose [Glucose]out  high[Glucose]out concentration [Glucose]in [Glucose]in GLUT stays low ATP ADP G-6-P Glycogen Low glucose concentration Glycolysis I does this maintain to a gradient Co-transport: SGLT Na+ binds to carrier. Glucose binding changes carrier conformation so Na+ Intracellular fluid Lumen of intestine that binding sites now or kidney face the ICF. Na+ [Na+] high SGLT protein Lumen ICF Glu [glucose] low [Na+] low [glucose] high Na+ is released into cytosol, where [Na+] is low. Release changes glucose- binding site to low affinity. Na+ Glucose is released. [Na+] low Na+ binding creates Na+ a high-affinity site for glucose. [glucose] high Lumen ICF Fairies Glu Lumen ICF an or allows sodium tobind give Signaling Pathways: the basic cascade Signal molecule Extracellular signal binds to molecule binds to a cell membrane receptor. Membrane receptor protein Binding activates triggers Intracellular signal molecules Rapid cellular responses alter Target proteins create Response Four Categories of Membrane Receptors Extracellular signal molecules ECF Channel Receptor Receptor Integrin Cell membrane Anchor protein Enzyme G protein Cytoskeleton ICF Receptor- Receptor-enzyme G protein–coupled receptor Integrin receptor channel Ligand binding Ligand binding to a Ligand binding to a G protein– Ligand binding to opens or closes receptor-enzyme activates coupled receptor opens an ion integrin receptors the channel. an intracellular enzyme. channel or alters enzyme activity. alters the cytoskeleton. movement Transduction Pathways Signal Extracellular Signal molecule fluid molecule binds to binds to Membrane receptor initiates Membrane receptor protein Signal transduction by proteins Ion activates channel Amplifier enzymes Intracellular alter signal molecules Second messenger alter molecules Intracellular Target Increase fluid Protein kinases intracellular Ca2+ proteins create Phosphorylated Calcium-binding proteins proteins Response Cell response Review Membrane properties depend not only on the lipid bilayer but the vast array of membrane proteins that regulate transport Membrane proteins serve both a transport and a communication function Signal transduction cascades are initiated by extracellular signals and function to regulate the internal state of the cell E109 Lecture 2: Endocrine Physiology Feedback Regulation S Body Temperature Stimulus Thermoreceptors Sensor Negative Negative feedback feedback loop loop Hypothalamus Integrating Center Sweat Glands Target cells Sweat Secretion Response Heat Loss Local Communication Contact-dependent Autocrine/Paracrine Gap Junctions signals signals Receptor i cells share left cell releases i releases peptide on its cytoplasm Smith to cell own membrane receptor on right then to next cell Local Communication Class concept as a gif Long-distance communication Endocrine System Slower, but longer lasting throughthe bloodstream Blood must travel to get to target cell Endocrine Cell without Cell with peptidehormone will cell receptor receptor onlybe relievedby Target cell cell with accepting No response receptor Response Nervous System Electrical signal Target cell Response Neuron Rapid, specific, short-lived Sites of hormone production all locations use hormones to regulate Hormones can be thebody produced by glands, specialized cells, or neurons iiiinto Hormones: Mechanisms of Action 1. Alter existing proteins peptidehormone e.g. change rates of enzymatic reactions [Enzyme] 2. Alter gene expression and protein synthesis e.g. Alter membrane permeability longterm effect Hormones: Classification Polypeptide Steroid takes longer Secretin pumped is Cortisol diffuse acrossmembraneintocell Not lipid soluble Lipid soluble Exocytosis Simple diffusion Pre-synthesized & stored in vesicles Synthesized on demand Dissolved in plasma Bound to transport proteins Short half-life Long half-life Receptors on cell membrane Receptors in cytoplasm or nucleus Activate 2nd Messenger systems Alter gene expression Modify existing proteins Induce protein synthesis Peptide Hormone Synthesis, Packaging, and Release 1 2 3 4 5 6 Messenger RNA on the Enzymes in the Secretory vesicles The secretory The hormone The prohormone ribosomes binds amino ER chop off the containing enzymes and vesicle releases moves into the passes from the acids into a peptide chain signal sequence, prohormone bud off the its contents by circulation for ER through the called a preprohormone creating an Golgi. The enzymes chop the exocytosis into transport to its Golgi complex. The chain is directed into inactive prohormone into one the extracellular target. the ER lumen by a signal prohormone. or more active peptides plus space. sequence of amino additional peptide fragments. acids. Endoplasmic reticulum (ER) Golgi complex To target Ribosome Active hormone Peptide Transport fragment vesicle 3 4 T 6 Secretory vesicle 5 Release signal Prohormone tailsmakethe mn hormone pronormone Capillary 2 inactive thisstepprevents endothelium thehormonereacting 1 withsomethingelse Signal Cytoplasm ECF Plasma sequence Preprohormone mRNA mm Figure 7-3, steps 1–6 Peptide Hormone: Action Activate membrane receptors and signal transduction Rapid cellular response Opens ion channel because hormones act Second messenger system on existing proteins phosphorylate KEY Proteins TK = Tyrosine kinase AE = Amplifier enzyme Cellular response G = G protein Figure 7-4 Steroid Synthesis generation of steriodhormone Petebindstoreceptor mrna nondetffffrotien modifies side chain for the steriod her a mitochondria cholesterol passbackthe free to modify release the sterloo Steroid Hormones: Action Blood Steroid Cell surface receptor 1 Most hydrophobic steroids are bound to vessel hormone plasma protein carriers. Only unbound hormones can diffuse into the target cell. 2a Rapid responses 1 2 Steroid hormone receptors are in the Protein 2 cytoplasm or nucleus. carrier Nucleus Cytoplasmic 2a Some steroid hormones also bind to Nuclear membrane receptors that use second receptor receptor messenger systems to create rapid cellular responses. DNA Interstitial 3 The receptor-hormone complex binds to fluid DNA and activates or represses one or 3 more genes. Endoplasmic reticulum Transcription Cell 4 Activated genes create new mRNA that produces mRNA membrane 5 moves back to the cytoplasm. 4 New proteins Translation 5 Translation produces new proteins for cell processes. Figure 7-5 Hormone Interactions 1. Permissiveness: one 2.Synergism: the combined effect 3. Antagonism: one hormone hormone enhances cellular of multiple hormones exceeds the decreases the cellular response response to another hormone sum of their individual effects to another hormone HE cancausethesameeffect in the s'tronger a together hormones A & B Cellular Response hormone B hormone A Time Hormone Regulation Sensor & Integrator Trophic hormones: endocrine regulation of hormonal release Often involves the hypothalamus-anterior pituitary axis Hypothalamus-anterior pituitary axis HYPOTHALAMUS 1 1 Neurons synthesizing trophic hormones release them into capillaries of the portal system. Capillary bed 2 Artery 2 Portal vessels carry the trophic hormones directly to the anterior pituitary. 3 Endocrine cells release POSTERIOR PITUITARY 3 their hormones into the second set of capillaries Capillary bed for distribution to the rest of the body. ANTERIOR PITUITARY Veins TO TARGET ORGANS Figure 7-16 Hypothalamus-anterior pituitary axis HYPOTHALAMUS Growth Hormone ACTH TSH LH FSH Prolactin IGF Cortisol Thyroxine Sex hormone secretion Gamete production Metabolic actions Breast growth Stress response Metabolic rate Milk production Growth Endocrine Pathologies Hypersecretion: excess hormone secretion Loss of feed back regulation excess hormone production Hyposecretion: deficient hormone secretion Loss/deficiency of hormone production Target cell pathologies Loss/down-regulation of target cell receptor Transduction of signal in target cells Review Negative feedback control loops allow us to regulate physiological function Local communication regulate the state of nearby cells Nervous system provides rapid but short lasting shifts in physiology, whereas the endocrine system produce slower but longer lasting affects The membrane permeability of peptide hormones and steroid hormones alters the nature and speed of their actions Endocrine responses can involve complicated cascades that can be regulated at various step