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Lecture notes

by: Susan Weng

Lecture notes Pgy300

Susan Weng
GPA 3.3
Human Physiology 300
David Pendergast, Malcolm Slaughter, Randall Hudson, Wilma Hofmann

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These are the notes I have typed up from the lectures. The notes are very detailed and is a great study tool for upcoming tests
Human Physiology 300
David Pendergast, Malcolm Slaughter, Randall Hudson, Wilma Hofmann
Class Notes
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This 31 page Class Notes was uploaded by Susan Weng on Sunday September 27, 2015. The Class Notes belongs to Pgy300 at University at Buffalo taught by David Pendergast, Malcolm Slaughter, Randall Hudson, Wilma Hofmann in Summer 2015. Since its upload, it has received 27 views. For similar materials see Human Physiology 300 in Nursing and Health Sciences at University at Buffalo.


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Date Created: 09/27/15
TABLE 144 Physiology Test 2 Review Cardiovascular Physiology Overall design of the circulation Question 1 Blood Question 2 Blood Flow Question 3 What is the function of the cardiovascular system Main Role in the body transportation system takes things from the environment and transports them to all the cells in Transport in the Cardiovascular System SUBSTANCE MOVED FROM TO the body Materials entering the body Oxygen Lungs All cells I I I l Oxygen is very critical for all Nutrients and water Intestinal tract All cells tissue in the body primarily used Materials moved from cell to cell to subsidize the substrates Wastes Someceiis Litertqr R Body is made up of 75 water if pm ces s39lm 1015 is lost your body will lrnmiiune cells anti Present in blood Available for bodies clotting dysfunction lWastes produced in body are continuously any cell that proteins needs them Hormones Endocrine cells Target cells moved to the liver for proceSSing Stored nutrients Liver and adipose All cells tissue Materials leaving the body Metabolic wastes All cells Kidneys gtltgtlt Metabolic wasteI produced Hieat Allcells Skin various cells eliminated by the Carbon dioxide All cells Lungs kidneys D75 of energy used by the body winds up as heat body is homoeothermic l has to maintain to body temp of 37 degrees Celsius lExcess heat is eliminated If body becomes hyperthermic it can cause damage to cells ex Fever Excess heat is eliminated through the skin Carbon dioxide changes pH of the body and damages ces if the C02 eves get to high l C02 is eliminated through the lungs Oxygen Transport to tissues Oxygen consumption V02 02 food Energy CO2H2O Oxygen is used to oxidize foods carbohydrates fats or proteins Blood is pumped by the cardiac output CO Blood ow from the heart to the tissues Oxygen is delivered to the tissues At the tissues oxygen is taken from the blood and used to provide energy 0 A certain amount of OZ is delivered in the arterial blood 0 We never want to use all the oxygen in the blood 0 Some OZ is remained in the blood and returned back in the lung for reoxygenation o The difference between how much OZ is delivered in blood and how much is returned to the heart is called quotThe arterial venous oxygen differencequot 0 V02CO CaOZCvOZ l Oxygen Consumption Cardiac Output how much oxy is the in the arterial blood how much oxygen remains in the blood and is returned back into the lung 0 quot Same can be written for Carbon dioxide just the difference is between the arterial content venous content 0 Oxygen consumption can be changed by changing the cardiac output or by increasing the amount of oxygen taken out of blood 0 Peripheral component Blood ow to a tissue extraction of oxygen at that particular tissue Cardiac output mainly the heart chapter 14 Peripheral circulation blood ow to the organs and tissues Chap 15 Blood carrying oxygen Chap 16 Main part of circulation is the HEART 7 7 y The Heart and TABLE 142 Maw Blaod Vessels Circulatlon operates by pressure Job of the heart Blue type indicates structures containing blood with lower H ea rt has FOUR major oxygen content recil type indicates wallaoxygenated blood cha mbe rs RECEIVES BLOOD SENlDS BLOOD Each chamber gets b00d FROM To from somewhere and Heart pumps blood somewhere Right atrium Venae cavae Right ventricle else Right ventricle Right atrium Lungs At the lungs Where 02 is Left atrium Pulmonary veins Left ventricle ta ken up a nd C02 is Left ventricle Left atrium Body except El minated for lungs Left ventricle pumps Vessels blood to the vast majority Venae cavae Systemic veins Right atrium Of the WhOle body Pulmonary Right ventricle Lungs trunk artery Pulmonary vein Veins of the lungs Left atrium Aorta Left ventricle Systemic ar teries Overall Design of the circulation runs by pressure Pumpdelivery tubes pumpto develop pressure tubes to deliver blood to organs and tissues Pump is essentially the heart 0 Heart Contracts like a muscle and generates pressure 0 Pushes blood out through the vessels which go the various organs and tissues 0 Closed circuit closed system heart pumps blood out blood goes through all the tube comes back to heart again a recirculation system 0 Right heart pumps through the pulmonary circuit from right heart through lungs and back to heart 0 Left side of heart pumps blood to the rest of the body systemic circuit 0 Circulation of uid is blood water red blood cells 0 Water develops the pressure 0 Red Blood cells carry the oxygen 0 System operates by pressure difference 0 Higher in the heart than blood vessels 0 SO blood ows away from the heart towards the organs and tissues 0 Valves only determine direction of ow 0 Make the blood ow in one direction 0 Arterial system blood pumped away from the heart 0 Takes blood from the heart out to the peripheral circulation tissues 0 Venous system blood returning to the heart Blood ow through the lungs is equal to through the systemic circulation Pulmonary blood ow cardiac output Difference ow in the pulmonary system has one organ LUNGS Systemic circulation multiple organs Blood ows by a pressure difference a resistance opposes it A lot of organs a lot of resistance that has to be overcome so the left ventricle has to generate a high pressure in order to get blood to ow through the systemic circulation The Systemic circulation has a high resistance so it needs to have a high pressure Right ventricle one organ so it has less resistance so RV has to develop less pressure than the left ventricle Venous system low pressure low resistance and high compliance l Flow returning to the heart has to equal the ow out of the heart Red blood cells that have oxygen bound to them take on a reddish color ex When you cut yourself the blood that comes out is red bc the blood cells get oxygen from the ambient air When blood ows through the lung it binds to 02 l so this blood is oxygenated When the blood ows through the systemic circulation the tissues take up 02 and so the blood coming back to the venous system it has less oxygen deoxygenated l takes on a color of BLUE lBlood is not bound to as much oxygen Maybe a TEST QUESTION DO all arteries carry oxygenated blood Answer No bc the pulmonary artery carries deoxygenated blood DO all venous vessels carry deoxygenated blood Answer No bs pulmonary vein carries oxygenated blood Artery Carries blood away from the heart Vein returns blood to the heart Time 3627 Overall Design CV system cont Systemic Circulation carries 02 to tissue Left heart COAortaArteriesArteriolesCapillaries High resistance thus high pressure Pulmonary circulation Oxygenates blood Right heart COPulmonary Artery etc Low resistance thus low pressure Venous Return high compliance capacity blood reservoir T VolumeA l PA VR C0 VR venous return from systemic to right heart VR from pulmonary to left heart Fluid that is pumped is made up of primarily water and blood Bloodl carries red blood cllsgnd oxygen Organic Li E ssmal 7 We such as 39ll39race elements Millrogenous and vitamins waste BLOOD acomposed 4m a Blood is made up of water water is important bc when the heart contracts it compresses the water and develops pressure o Ions in water make plasma 0 Organic molecules l amino acids proteins glucose lipids nitrogenous waste 0 Trace elements and vitamins Gases delivery of 02 and removal of C02 Gas Transport transported by red blood cells Blood also has white blood cells Main function of white blood cells VARIOUS KINDS ght diseases infections Red blood cells is Cellular BLOOD moomggsed eiememts W Winite blood cells mdUde Platelets 35 7 53 in km 1 MonoWiles 3319 i 139 2 film I av 1quot r j Basophils limo 1D 15 Platelets These are relatively small amount in THE blood l Clotting and tissue damage of blood vessel Red blood cells main focus quot Where question about blood will come from ii ii Hematecrit Hemoglobin g Htde bloctil ilted celll count CEll SftlL ngqf 39 total white cell count cellsfilJLl Differential white cell count Neutroiphils lEosihciphils Basophils 100 Lymphocytes ller liviehocytes ESE Platelets per luL ll deciliter cllL39l mu mL 42 I packed I red cell MALES does 54 14 h 45 63 gtlt le til Til 2x 103 5070 1 4 ii We 2040 2 B lstiaso gtlt 103 FEMALES wit 47 12 i 33 55 x il 4 11 x 103 5070 1 e4 lt1 2040 2 8 lSMSU x 103 quotquotquotquotquotIf you take a small vial of blood after centrifuge the heavier elements sink to the bottom and lighter elements go to the top Heavier material in this vile is red blood cells when centrifuged it is called packed red blood cells Also called hematocrit 42 l carries oxygen 0 A difference between males and females 0 Males have a slightly higher hematocrit than women 0 One has to do with the average body size 0 Have to do with the production and destruction of red blood cells during menstruation in women 0 Hemoglobin what the red blood cells are made up of o Hemoglobin is the substance that oxygen binds to o For men and women there is a certain amount of hemoglobin each Higher for men lower for women In the chart the numbers are based on the average there are difference in each individual person Next level is white blood cells lt1 Plasma Volume water and solutes 58 l plasma volume is for developing hydrostatic pressure REMEMBER THE BALANCE THE l Remember the that is plasma that is red blood cells that males have more RBC and hemoglobin than females I Although these are the percentages we have to consider the total volume of blood The volume of BLOOD IN FEMALES is 45 LITERS BLOOD IN MEN is 56 LITERS Difference in blood volume is due to the fact that men are normally larger and need more tissue Don t need to know Main component in hemoglobin is IRON received in diet Red blood cells last 23 weeks because they lose their ability to carry 02 I Old RBC is destroyed in the spleen and turned into bile in the liver Red Blood cell is a concave disc Can go through all the blood vessels in the body I Have attachment proteins 0 At the attachment proteins where oxygen binds Each molecule of blood has 4 attachment binding proteins 0 Therefore each red blood cell can carry 4 molecules of Oxygen Cytos keleton fillllamenit quot 32an o The more red blood cells the more oxygen you can carry Actin The amount of 02 in the arterial side is called The Contentquot of Oxygen The content of 02 is determined by the amount of 02 binding to the at bindingattachment sites 2 The cytoskeleton creates the unique shape of RBCs Megakaryocytes are giant cells with multiple copies of DNA in the nucleus The edges of the megakaryocyte break off to form cell fragments called plateletsn Platelets Endoplasmic Red blOOd cell reticulum a quotThe platelets are associated with a cell like the one picture above 0 They fall off and are in the circulation SO if you get a hole in a blood vessel the platelets clog up the hole and stop you from bleeding to death 0 Clotting l function of the platelets 2 MAIN Functions of Blood 1 It allows the development of hydrostatic pressure 2 Carrying red blood cells and it carries oxygen Blood ow is a product of the pressure difference Pressure difference between two points in the circulation AP P1 P2 ex P1 is the heart and it s pressure is 100 P2 is vein and it is 20 there is a pressure for blood to ow from the heart to the vein Resistance to ow organs and tissues provide a resistance to blood ow R l Radius of the blood vessel to the 4th power Radius 1r4 length BF 1L blood viscosity BF 1v R 1r4 Blood viscosity is pretty constant in the body and the length of blood vessel doesn t change in adults o BFAWR BF proportional to AP ie increase AP increased BF 100 mm Hg liOO mm Hg ll 3 AP 0 so no flow b No pressure gradient so no ow KEY P Pressure AP Pressure giradlient 100 mm Hg 75 mm Hg l Flowe gt gt AP 100 75 25 mm Hg flow Is equal 40 mm Hg 15 mml llg Flow a c Fllow depends an AP not absolute P AP 40 15 25 mm Hg KEY P E Pressure AP 1 Pressure gradient Decreased AP decreased BF BF blood ow inversely proportional to R resistance Increase R decreased BF Decreased R increased BF INO CHANGE Lecture 2 Anatomy of the heart Blood ow through the heart Autonomic regulation of the heart Anatomy of the heart THE lHE HT sternum Prasltiln af 0 7 sail l lunar aalaas Diaphragm 1quot m l quot l l asa f Li l I r i heart A rapeHf E heart 1 M g F lFiaai an any aiml HHHEE an all 39ll39ll lll39E lhaart lies a the lialHE ali tlha tharax Heart is inside the nbcage 0 Important because the heart can be caused to contract electrically 0 Can be excited mechanically o The ribcage will protect the heart from a mechanical impact Size of the st Behind the sternum Obliquer oriented Females have generally smaller hearts because men have larger bodies and more blood ow 0 What is the doctor listening to when he places a stethoscope on your chest l He is listening to the 4 valves H TDHT F THE TH EIE E 39ifll 39I39ll39l39hl39ll39ii gland Tracilea First Ir l39b cut Lu l lungs Ella ah ram f Elana segment mmwedj Wl ll la lESaEiphig39uss a w W Superilur a Ful munawve39iin arena ma Left atrium ight 39 LLE FE 39il39E trllEli atrium Pericardial Hightuentricle Pueriizairdium Eternlum I39jd Eupal m Inf transverse plans In ilk DAorta the big blood vessel red l Pulmonary artery blue Heart itself invaginates into the left lung A muscle called a diaphragm ventilates Diaphragm in uences the interthoracic pressure with is important for the heart l A view from thetop Heart is hanging in the middle between the esophagus and the sternum Venous side runs parallel to the arterial side 0 The aorta coming from the top of the heart means the 2 arteries to the brain are right off the aorta lmportant for body to know what pressure in going in the brain Arterial side gravity helps circulation Venous side impeded by gravity lA special circulation has to get the blood from the veins to the right atrium Eli r IE3 vessels that wellkm emata bland are mill these with less well le i t l bland are lhliuei Heart is encased within a membranous uid lled sac called pericardium l Pericardium is above the diaphragm Function to protect the heart from infection primarily o Pericarditis Infection of the pericardium 0 Dangerous because if the pericardium is infected it could get to the heart and cause it to fail Pericardium muscle itself is called a myocardium l a striated muscle similar to skeletal muscle but has its difference 0 The contraction of the myocardium that causes the pressure in the heart Anita Pu lmamaw Eapeflar i 39 arteryi tieha aea 7 Aeriete at lelt atrium Eartartar EllieF55 and vein Hiaht atrium meat clg L lLeIt i ale f Theaentitles enmity the built at the hem The arteries and veins all attaeh he the base aftlee heaft ventricle and atrium Back posterior Blood vessels on the outside of the heart are called coronary artery and coronary vein Responsible for delivering blood required by the myocardium 4 coronary arteries 2 in the front 2 in the back Front anterior l The right anterior coronary artery takes care of the right ventricle and atrium Left anterior coronary artery takes care of the left Since the left ventricle has to construct a pressure 4X the right ventricle the left ventricle is much larger more muscle l Circulation in the left ventricle is more important than the right ventricle Veins run parallel to the arteries in the heart as well as the rest of the circulation gm Puilrnn aryr 39 isem39illuirnalrsels39e Hill r L pulmeimergg Left pulmeirnaiw arteries 7 arteries Superiier s leiit pulml39lil l quotarena seea r sreins Higihrtatriurn 7 I 139 L 397 i39 Left atrium f y i H LL i L V Eusp ef the ear i i L hieumidflvaiee 39 In 4 ne er 395 Illusp safe right Eherdse tendineee i l 39l l Etr39ieusp isl hare I if h iii jig 39r r Papillary rrIusles Lel t sentr39iele Hig st ventricle linliferir sienna earIa m escennlinig erta it neweir threugh the heart is ensured IslII sets f eahres Direction of blood ow within the heart Since the heart pumps out what it gets back we always start the circulation with the right atriuml chamber that gets blood back from the heart 0 It receives blood from the superior and inferior vena cava o No valve between the vena cava and right atrium so blood always ows in that direction 0 Right atrium then pumps blood into the right ventricle 0 Since we don t want blood to ow backwards there is a valve between the right atrium and right ventricle Called AV valve tricuspid valve 0 AV valve tricuspid valve makes sure the blood ows from the right atrium to the right ventricle 0 When right ventricle contracts it causes AV valve to close 0 When right atrium pressure gets high enough it gets the pulmonary semilunar valve to open and blood ows out to the lung 0 From the lung blood ows back to the left atrium o No valve between pulmonary vein and left atrium Blood ows from left atrium to left ventricle 0 Another valve is there called AV Bicuspid valve 0 Only opens when blood is owing from the left atrium to left ventricle When left ventricle contracts AV valve closes and aortic valve opens and blood is put out into the aorta ln aorta blood goes through the systemic circulation Remember blood ows by PRESSURE When ventricles are relaxed pressure is very low Atrium is on top of the ventricles so gravity pulls blood from the atrium into the ventricle even without an atrial contraction l Eventually there is atrial contraction l increases pressure VALVES Set directions of ow do not contract operates 100 by pressure pressure difference between 2 chambers Papillary muscles and tendons stabilize the valves DO NOT contract It is the pressure difference that drives the valves to open and close If the valves do not close properly then part of the blood would ow back to the atrium and there would be less pressure and less ow If valves leak it is called murmurs l causes retrograde ow decreases pressure through the pulmonary and systemic circulation 25 of population has leaky valves l usually a relatively small amount abut 1015 o If the leakage is more than 1015 it compromises body s ability to deliver blood and oxygen l leads to fatigue because there is not enough oxygen going to the organs and tissues Irlt dlrfs t Myu miilll quotWEElE Heart is made up of muscle l striated I5 5 EE muscle similar to muscle in the skeletal system Two major differences 0 Distance between the bands sarcomeres is much shorter and force is very high Myocardium is almost exclusively dependent on oxidative metabolism Delivery of 02 to the heart is critical to support its contraction lAny clogging of the coronary arteries deprives the heart of oxygen and damages the heart I Myumr iil mustllie tells nine ria melted have a Elill lliE I liutlialu5El and are attired 1 Bath Ether by speciailite junc is knuwrl as r bErizalated disks i it Ventricular contraction 2 AV valves are closed called tricuspid because it has 3 cuffs Ventricular relaxation AV valves are open pulmonary artery and aortic valves are closed Blood ows from atrium to ventricles Muscle Have bers sarcomeres nucleus and large number of mitochondria Cardiac muscle has to contract in a certain direction In Atrium we want it to contract from the top of the heart to the ventricles In the ventricles we want it to contract from ventricles to atrium SO the heart tissue has a special electrical conducting system llndividual bers are isolated from each other except for the area called intercalated disk lntercalated disk makes sure the electrical signal passes in the right direction to the cardiac muscle contracts in the right direction it is a specialized characteristic of the excitation of the cardiac muscle The sarcomeres are shorter contract less distance but generate more force How we excite the cardiac muscle Once the heart is stimulated it contracts on an all or none basis lThe entire muscle rst the atrium then ventricle All the bers of the atrium or ventricle is excited with one excitation Heart has primarily 2 phases 1 Systole when the heart is contracting when heart is excited 2 Diastole When heart is not excited We have to look at a neural control system that excites the heart System that control heart beat is called the Autonomic Control System of Cardiac Function Autonomic system Happens automatically do not have to think about it Neural control system that tells the heart how often to beat and how forcefully to beat Autonomic control system ACS comes from the cardiovascular control center to the heart ACS has TWO major branches lSympathetic nerves Sympathetic Nerve Activity SNA l increase the excitability of the heart causes it to beat faster and more forcibly contraction Decreasing sympathetic nerve activity has the opposite effects lowers heart rate decrease force of contraction lParasympathetic nerves parasympathetic nerve activity PSNA ldepress the heart rate If PSNA is increased heart rate is decreased does not affect the contraction of heart only the rate Heart rate and force of contraction is determined controlled by the balance of the SNA and PSNA l Controls the pacemaker of the heart Pacemaker located on the heart l innervated by the sympathetic and parasympathetic nerves l SO a balance change in the sympathetic and parasympathetic activity will either increase or decrease the heart rate 0 WHY lHeart rate and cardiac function has to change on a millisecond by millisecond basis bc the metabolic demands of the tissues of the body are constantly changing Heart has to have a immediate response system in order to meet the demands of oxygen delivery o If PSNA is high heart rate is low o If SNA is high PSNA is low heart rate will increase 0 Heart rate below 100 beats a min is heavily in uenced by PSNA Heart rate above 100 is dominated by SNA How does pace maker cell then set the heart rate since both PSNA and SNA affect it Normal values of heart rate HR Sedentary resting has a heart rate of 6080 beatsmin 70 average Maximal 220 on avg Elderly resting 7080 bmin Maximal 220age Athletes resting 4565 bmin Maximal 185 bmin Their autonomic control a lot of PSNA and less SNA Sex differences females slightly higher heart rates 7080 range Males 6070 age What is the autonomic control that would give these values People who have higher PSNA have lower heart beatsmin and lower SNA quot And Vice versa Cardiovascular control center located in brains tem Has 2 pathways lsympathetic and parasympathetic They both have difference transmitters Sympathetic has a transmitter called Norepinephrine NE 0 NE binds to Bl receptors changes the ion ux increases rate of depolarization and increase heart rate Parasympathetic has a transmitter called Acetylcholine Ach o Ach binds to muscarinic receptors increases potassium and decreases calcium 0 Hyperpolarizes the cells and decrease the rate of depolarization o Decreases Heart rate f ffquot H V l I Cardiovasoular control woenter in moduli a Oblongata l quotf K KEY l Sym pathetic neurons NE l Kr l Freoelptors of autorhythlmio cells l 1 Rate of depolarization l Naquot and 032 influx J l Parasym pathetic neurons ACh l Musoarinio receptors l l rquot u 7 x4 3 of autorhythmio cells i K efflux 833 influx Hyperpolari zes cell and iv rate of depolarization l Kid in Heart rate J Heart rate J Lecture 1 OVERVIEW Resistance is pulmonary system is much less Blood has 2 components water and red cells Percentage in blood hematocrit hemoglobin red cells fquot Integrating center V 397 Efferent path Effector Tissue response Remember that 1 Sympathetic nerves and NE bind to Bl receptors 2 Parasympathetic neurons and Ach bind to muscarinic receptors Both the receptors are on the pacemaker cell Connect the links that leads to increased and decreased heart rate Blood ow directly proportional to pressure and inversely proportional to resistance I Smaller blood vessels have higher resistance bigger blood vessels have lower resistance Lecture 2 Overview 0 Anatomy of Heart 0 O O O O O O 4 chambers 4 valves Blood ows from right atrium to right ventricle out to the pulmonary artery to the lungs I comes back through the pulmonary vein to the left atrium to the left ventricle and then to the aorta Valves operate by pressure If pressure is higher in atrium it pushes blood into the ventricle If pressure is higher in the ventricle it closes the AV valves and opens the pulmonary arteries and aortic valve Heart have basically 3 layers pericardium sac around the heart myocardium muscle around the heart endocardium 4 major blood vessels 2 in front anterior 2 in back posterior Blood ow through the heart Autonomic regulation of the heart Control of heart beating originates in the cardiovascular control center in brain stem medulla oblongata Lecture 3 Specialized conduction system in the heart Electrical activity of the heart excitation Specialized conduction system Electrical activity of the heart cardiac muscle Electrocardiogram measure the electrical activity of the heart itself Specialized conducting system SA node sinoatrial node l The pace maker of the heart where PS and S systems innervate the SA node and determine the balance at which the SA node res The depolarization from the SA node is propagated through the intermodal pathways down to the AV node atrial ventricular node At AV node there has to be delay which allows the 2 atrium to contract Signal is vividly propagated to the AV node where it is delayed During delay the ring of the Sa node actually propagates excitation a depolarization through the 2 atrium and causes it to contract Once the atrium is nished contracting it goes back to a relaxed state diastole electrical diastole Signal is propagated form the AV node through the AV bundle which takes the signal through the septum between the atrium and ventricle and then it splits into the bundle branches left and right Signal is then propagated to the apex of the heart where it curves around and forms purkinje bers Purkinje bers eventually invaginate in the myocardium Once the Av node res the signal is rapid propagated around the apex of the heart and transmitted through the myocardium l brings about excitation l a delay and then the SA node res again With each beat the entire heart is depolarized and eventually contracts rst atrium then ventricles Specialized conducting system are cardiac cells and account for 1 of cardiac cells Cardiac cells but have nerve like properties means that they rapidly conduct electrical signals Because the SA node is the pacemaker the ensures that the 2 atriums contract rst together and same for ventricles when atrium is in a relaxed state If heart is not contracting it is not developing pressure System itself can act as a pacemaker can excite itself a characteristic called autorithnicity ex If a person has a heart transport when old heart is taken out the nerves are cut The new heart beats SA node has an automatic rate of 100 where as AV node has an automatic rate of 60 If SA node res Av node will not be able to excite the beat SO lf SA node res we will have atriums contracting before ventricles Once AV node res it is propagated in a normal way IF AV node doesn t re then the AV bundle bundle branches or purkinje bers also have the characteristic of automaticity ability to excite itself Wouldn t want the purkinje bers to re before the AV node so the rate of the purkinje ber is much lower than the rate of the AV node down 40 beatsmin Damage to the AV node or SA node the heart will still beat If the heart beats l when the ventricle 5 contract will it pump blood Yes but the output will be very low Specialized conducting system is mostly always functional I Also has the same pattern in everyone very uniform pattern of excitation in the heart unless there is a defect in the nodes Defect in the SA node we wouldn t want the heart to go at a slow rate Pacemaker can be added to the chest Sends electrical signal to SA node and causes it to depolarize and then propagate the signal through the pathways normally Pacemakers very common invented in Buffalo by a company called Great Batch What is the characteristic of these specialized cells to have pacemaker potential To understand that we have to look at the ion uxes or excitation in the specialized conducting cells l These specialized conducting cells occupy 1 of the heart l The other 99 are the contracting cells Excitation of the specialized cells is different from the contracting cells Specialized cells have automaticity contracting cells do not Contracting cells have to be stimulated by the specialized conducting system in order to be excited Membrane petentiel lim ll39j 2v 39liThlreehel d 71 a e F e EE39 iEI EEiF petentieil Time a The pacemaker petentiel gradually be lees negative until it reeehee threehlli triggering an amen Fli t39E l iHllL is this system ReasonThe depolarization is in ux of sodium lThe in ux of depolarizes the threshold Once the cell threshold then opening of the channels the channel to and have an CA2 Ae n eeet al Membrane pletentiel lentil Depolarization of the specialized conducting cells Starting from 60mV as a function of time the cell slowly depolarizes Once the cell hits threshold it depolarizes by a big action potential l causes excitation l starts with a slow inward depolarization followed by a rapid depolarization l Then a repolarization back to the base line Each one of Equot l39Illet Filequot in lien mimemeets during an ae un these is a heartbeat Question Why this way sow inward caused by an sodium ce towards reaches we have calcium which allows open very wide INFLUX OF quotWm 52 339 and paeernalter putenti all l Causes the rapid depolarization lOnce the peak is hit the cell repolarizes l Calcium and sodium channels are closed l Potassium channels are open and it is pumped out of the cell l repolarizes cell to 60mV quot These are the ion uxes now why do we have them They are quite unusual and specialized in the specialized ces Membrane potential EMU Membrane menti a my 1 us A i l l i l Lets elitequot l channels open If channels pan l m Same Ital channels open llf channels clause HEquot channels close Ea channels Else Iii channels open 7 r channem T open Time h ll State inf walrleus ion channels Unique characteristic of specialized conducting cells is that they have funny channels If llf channels open in the beginning and open a small amount which allows a slow inward ux of sodium I Once the If channels let in enough sodium some Ca2 channels open and eventually all the Ca2 channels open l rapid depolarization Then the Ca2 channels close and K channels open repolarizing the cell it its initial base and K channels then close quot That is considered one heart beat l a normal beat How do we change the rate of pace maker potential What effect does the parasympathetic system have to slow the rate and what effect does the sympathetic system have to speed up the rate Funny Channels If funny channels open wider more Na will ux in and it would take a quicker amount of time to reach threshold If funny channels do NOT open as wide Na ux will come in slower and take a longer time to reach threshold slope I W 2wu l 396 7 Emlt airmail Sympatlh El n stimulation Delpruila riled More rapid depularizati nn will be more shallow lslower heart rate What happens to the depolarization when we use sympathetic stimulation I Sympathetic stimulation a ll LE I 315 W Time sec i has a little less Ml polarization has a rapid rise of sodium to the threshold Takes sympathetic stimulation less time to get to threshold since funny channels are opened wider Results in more heart beats than normal stimulation in a given period of time If we have a sustained increased in sympathetic activation what happens is that the cell becomes less polarized so it takes less time to get to threshold M D Membrane patenl l Ilme EH Hyperpulalri39zed Normal I arasympatlhetii stimulation What happens to the depolarization when we use parasympathetic stimulation lThe membrane potential is l hyperpolarized has a 39 greater negativity Elm delp l39arl39m39m lFunny channel is opened lb 1 1951 2 less wide which leads to a slower ux of Na2 Time sec 139 So it is the effect of the autonomic system on the membrane potential of the SA node that changes the heart rate normally of a spontaneously beating heart If the SA node is damaged that is when clinically a pace maker potential has to be put in which sets the rate by electrically stimulating the SA node The depolarization of the specialized conducting cells causes the depolarization of the myocardium Action potential of a cardiac contractile cell There is a different excitation or action potential in the myocardium than in the specialized conducting cells Miamalaria PIE potential mm l in Ft E E 5 Si 1IIII First stays in a polarized state conUnuoqu Polarized to 90mV l means that the contracting cells have a higher threshold of excitation Threshold can be met with the depolarization of the specialized cell PE 3 Fermeahlllitw t lam1 l wan Aquot 1 39iiF39Eili lill Wiend l PM Starting from the polarized state the quot depolarization of the specialized cells T rapidly opens the sodium ion channel 4 DA rapid in ux of sodium occurs which leads to a very rapid depolarization in mi mu emu Once cell is completely depolarized maimed r the cell remains polarized at a plateau Hm Mmhmmhamm for a longer period of time than normal l remains polarized at a plateau 2 Hak39itham elwrien THEN a repolarization occurs similarly Efflfmm el e to the specialized cells l but it takes E Ea ehaim elsepien astl tchanmels clause quite a longer for the Ca2 Eaf haimnelss lseislmw Itquot EI39IEHFIEEE open channels t0 CIOSE and fOIquot K t0 be nesting Fitiainrtlal pumped out to repolarize cell Role of Specialized cells to excite contracting cells Role of contracting cells is to contract and generate pressure primarily in the left ventricles In order to develop pressure the ventricles have to squeeze the blood 0 In order to squeeze the blood we have to sustain a contraction for a long period of time explains the plateau 2 o The depolarized plateau keeps the myocardium contracting o Myocardium starts contraction from apex and over towards the aortic and pulmonary valves 0 The depolarized plateau is very important for developing the pressure in the heart that is needed to eject the blood 0 quotOnce all that occurs the cell automatically repolarizes and it will remain polarized until the next ring of the specialized conducting cells 0 Another important aspect of this action potential During the phase from the rapid upswing to the repolarization 4 to 3 in the graph it is called the Absolute refractory period 0 Absolute refractory period this cell can not be excited again no matter what happens to the specialized cell o The cell will contract and sustain contraction to build up pressure in the ventricle o A safety feature to make sure the ventricle contracts forcefully enough to generate enough pressure to eject the blood from the heart Has to do with the very highpolarized state the beginning and a very high threshold for excitation lOnce action potential is propagated the myocardium will contract the depolarization precedes the contraction l The contraction follows the waveforms If there was a defect in the specialized cells and we correct it with a pacemaker we would usually correct the quotexcitation partquot of the contracting cells EXEPTION if there is damage to the ventricular contracting cells bc of deprived 02 it will not conduct the signal properly and so the action potential would look different heart will not contract properly Hi l u lEF Eir ninq ptE al d mi h l n licy g Membrane pliEIrllrial 7 Mcni tratt39iEE 5E1 39 39lnflrfalf cell InternalsElia Elk wish gap juri i ain rii ni F uttlrhvthfn m t ll a rapide Spr a tu adi nl anftrairltili EL l a thru gl ig l jimnlrli39ilflzi quot Wave of excitation in the framework of the heart itself There is the SA node and atrial contracting myocardium beneath it When the cells of the SA node depolarize you will notice a specialized conducting pathway depolarization l Then signal is propagated to the myocardium notice that the myocardial contraction goes from the SA node to the ventricles l Membrane potential of the contracting cells can be seen In the atrium the signal goes from the SA node to the ventricles therefore excitation causes contraction pushing blood into the ventricles I39quotll 1 11 ill Pattern of excitation ensures blood is pushed from the atrium to the ventricle and then the ventricle out through the pulmonary artery and aorta Part of the coordination of the system Doesn t resemble either specialized conducting cells or myocardial contracting cells l Signals are mixed l The rst wave is the excitation of the SA node and atrium The peak represents the ventricle IiiE11 5 The next wave IS repolarlzatlon Ea the elle mtmrdlaegren remresen the ELIET iiiT iEEl elleetrlcal activiti ef all sells resented ren the Eli date at the Ethelr L1 El m if l El F l l l l Ventricular and atrial depolarization of the myocardium Myocardium in terms of depolarization is the MOST important bc 99 of the heart is contracting myocardium 1 see iquot hall mementrliculer Harden petenirlaul he remanded frnn a single cell using an intraeellmlagre e rtreizle write that the eeltage change much greater when lI39EEIEiFijEij ln eaetellulerl e quot Can be measured in the heart by placing electrodes throughout the heart and record signals from the upper part of the heart and lower part Another way to look at the electrical activity of the heart Heart is immersed in the body which is 95 water So the depolarizations of the heart are propagated through the water component of the body and it goes through all the tissues of the body For ex Once depolarization happens if electrodes are placed on the chest we can measure the change of excitation on the chest Electrodes are called an electrocardiogram represent the summed electrical activity of all cells recorded from the surface of the body quotRe ects the depolarization of the specialized cells the atrium and ventricle etc HWhm iE39QiITIEWiZ 8 Ha q iii 75 a l T aw U u A QEE Empi First wave is called P wave quotOnly thing that changes would be the rate of the pattern The electrocardiogram coincides with the electrical events of the heart 0 Beginning of the P wave SA node is ring Then atrial depolarization in the PR interval Once depolarization is complete in atrium The AV node and bundle branches purkinje bers re 0 QRS I ventricular depolarization 0 And ventricular myocardium stays depolarized which is the period between the S and T wave 0 Then we have repoarization of the ventricle T wave PR segment and ST segment can show the actual time of propagation The electrocardiogram can diagnose whether or not the electrical system is behaving normally Ex If SA node were damaged there would be no P wave there would still be a QRS wave because of automaticity there would also be a T wave quot In this case the heart would still pump blood lf heart rate was sped up or decreased the time between the T wave to the next P wave would be changed If heart rate went UP period between T wave and P wave would be shorter If heart rate went DOWN period between T wave and P wave would belonger WAVE PATTERN WILL ALWAYS REMAIN the SAME l a great way to diagnose cardiovascular disease Excitation of the heart can be looked at from the electrocardiogram and specialized conducting cells If we start at the SA node when it res we have a P wave l P wave is then propagated through the atrial myocardium lThen P wave is completed When AV node res we have the Q wave At it is propagated through the purkinje bers we have the R wave and then the S wave l Then the propagation of the signal through the myocardium l Then T wave occurs which is repolarization The whole wave is called electrical systole Period between beats between end of T wave to start of P wave is called electrical diastole The contraction of the muscle follows the excitation of the specialized conducting cells When the myocardium contracts the pressure will go up push blood into the ventricles when ventricles contract the pressure will go up and push blood out of the aorta Lecture 4 Contraction of cardiac muscle Force of contractioncontractility Starling curve enddiastolic volume Stroke volume Cardiac output


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