Circulatory System Part 1-4 PDF

Circulatory System - Part 1 We acknowledge and respect the lək̓ʷəŋən peoples on whose traditional territory the university stands and the Songhees, Esquimalt and W ̱ SÁNEĆ peoples whose historical relationships with the land continue to this day. Copyright © 2008 Pearson Ed...

Circulatory System - Part 1 We acknowledge and respect the lək̓ʷəŋən peoples on whose traditional territory the university stands and the Songhees, Esquimalt and W ̱ SÁNEĆ peoples whose historical relationships with the land continue to this day. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Why do animals need a circulatory system?  Small unicellular organisms do not need one  Receive molecules by diffusion – rapid in seconds  Large animals cannot rely on diffusion  too slow – years to diffuse over a meter of tissue  Must use bulk flow to transport molecules rapidly to their target cells transport of nutrients Oxygen to Circ system the in a timely matter body Salt Removes con waste Regulate Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Reg top Functions of the Circulatory System  Transport O2 to cells  Remove CO2 and waste  Transport nutrients  Regulate salts  Regulate temperature  Transport signaling molecules eg. hormones  Immune response immune calls in Fluid transported Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Components of Circulatory Systems  Circulatory systems move fluids by increasing the pressure of the fluid in one part of the body  Fluid flows through the body, “down” the pressure gradient  Three main components are needed  Pump or propulsive structures  For example, a heart  System of tubes, channels, or spaces  Arteries –delivers blood away from heart to  Veins –returns blood toward heart  Capillaries –fine tube-like structures where materials are exchanged between blood and tissue  Fluid that circulates through the system  For example, blood, hemolymph Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Types of Pumps  Chambered hearts  Contractile chambers  Blood enters atrium  Blood is pumped out by ventricle  Skeletal muscle  Squeeze on vessels to generate pressure  Pulsating blood vessels  Peristalsis  Rhythmic contractions of vessel wall pumps blood  One-way valves help to ensure unidirectional flow Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Closed and Open Circulatory Systems  Closed  Circulatory fluid remains within vessels and does not come in direct contact with the tissues  Circulating fluid is distinct from interstitial fluid no mixing  Molecules must diffuse or be transported across vessel wall  Open  Circulatory fluid comes in direct contact with the tissues in spaces called sinuses  Circulating fluid mixes with interstitial fluid F Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Types of Fluid  Interstitial fluid  Extracellular fluid that directly bathes the tissues  Blood  Fluid that circulates within the vessels of a closed circulatory system  Hemolymph  Fluid that circulates in an open circulatory system  Lymph  Fluid that circulates in a secondary system in vertebrates called a lymphatic system Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Vertebrate Blood  Separates into three main components when centrifuged  Plasma  Erythrocytes (red blood cells)  Other blood cells and clotting cells (Leukocytes and thrombocytes (platelets))  Hematocrit – Fraction of blood made up of erythrocytes Figure 8.45 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Composition of Blood Plasma  Primarily water, containing Dissolved ions and organic solutes (HCO3) Dissolved proteins Carrier proteins – albumins, globulins Clotting factors – thrombin, fibrinogen Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Red Blood Cells (Erythrocytes)  Most abundant cells in blood of vertebrates  Contain high concentrations of respiratory pigments (hemoglobin) Major function is storage and transport of oxygen each RBC 250 million hemoglobin Or binds Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Some Animals Lack Circulatory Systems  Sponges, cnidarians, and flatworms  Lack circulatory systems but have mechanisms for propelling fluids around their bodies  Sponges  Ciliated cells move water within body cavity  Cnidarians and flatworms  Cnidarians: Muscular contractions of the body wall pump water in and out of body cavity; Flatworms: Diffusion. N TLEY matter EFFIE s.EE Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings EEEEiEhEfEe  Annelids – open and closed circulation Tube worms open Mixes Earthworms closed Peristalsis Uses blood to move vessels through Figure 8.4 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Molluscs – open and closed circulation so Bivalves  All have hearts and 02h system some blood vessels Pushes  Most have open systems  Only cephalopods have closed systems SquidsOctopiscuttlefish Figure 8.5 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Arthropods – Crustaceans – open circulation c All haveOpen cire systems  Circulatory systems become more EEE.EE complex in larger animals  Small sinuses function as vessels  Some control over distribution of hemolymph flow in body More structured butOstiaclose w they run Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings ITSFigureThen 8.6  Arthropods – Insects – open circulation  Relatively simple open circulatory system  Multiple, contractile “hearts” along dorsal vessel  Insects use a tracheal system for most gas transport Figure 8.7 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Evolution of Circulatory Systems Figure 8.8 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The Circulatory Plan of Vertebrates  Heart contracts to increase the pressure of the chamber  Blood flows away from the heart in arteries  Arteries branch, small arteries branch into arterioles  Blood flows from arterioles into capillaries  Capillaries - diffusion of molecules between blood and interstitial fluid  Capillaries coalesce to form venules  Venules coalesce to form veins  Veins carry blood to the heart Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Vertebrate Blood Vessels Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Vertebrate Blood Vessels  A complex wall surrounding a central lumen  Wall composed of up to three layers  Tunica intima (internal lining)  Smooth sheet of endothelial cells (vascular endothelium)  Tunica media (middle layer)  Smooth muscle  Elastic connective tissue  Tunica externa (outermost layer)  Collagen and some elastic fibers  Thickness of the wall varies among vessels  Veins have one-way valves and arteries do not Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Capillaries  Lack tunica media and tunica externa  Continuous ghettogether  Cells held together by tight junctions  Skin and muscle  CNS- blood brain barrier  Fenestrated  Cells contain pores  Specialized for exchange  Kidneys, endocrine organs, and intestine Tau  Sinusoidal IEEE  Few tight junctions  Most porous for exchange of large proteins  Liver and bone marrow Figure 8.11 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Circulatory Patterns of Vertebrates  All vertebrates have a closed system  Water-breathing fish  Single circuit see  Air-breathing tetrapods (amphibians, reptiles, birds, mammals)  Two circuits pumptolungs  Pulmonary circuit – right side of heart  Systemic circuit – left side of heart runs body to Figure 8.12 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Circulatory Patterns of Vertebrates  Water-breathing fish  systolic pressure 30-45 mm Hg  lower metabolic rate and O2 consumption lower bloodpressure  mammals  systolic pressure 120-180 mm Hg  higher metabolic rate and O2 consumption more active iii susson Capillaries in the lung transport Oxyerfaster they Arethin Figure 8.12 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Amphibians and Reptiles  Heart is only partially divided Crockodillion 4chamberedheart  Two atria and one ventricle  A three-chambered heart (frog), 5 chambered (lizard) tins  Blood from both atria flow into the ventricle t  Oxygenated and deoxygenated blood can mix Notforcrocodilian  Oxygenated and deoxygenated blood are kept fairly separate by a mechanism that is not completely understood  Ventricle pumps blood into pulmonary and systemic circuits  Blood can be diverted between pulmonary and systemic circuits Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Summary components – pump, tubes, fluid open, closed circulatory system Animus w Nocirculatorysystem blood components – plasma, RBC, WBC blood vessels – arteries, veins, capillaries types of each pulmonary and systemic circuits Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Circulatory System - Part 2 We acknowledge and respect the lək̓ʷəŋən peoples on whose traditional territory the university stands and the Songhees, Esquimalt and W ̱ SÁNEĆ peoples whose historical relationships with the land continue to this day. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Arthropod Heart – Decapod Crustaceans  Heart pumps hemolymph out via arteries ostian  Blood returns via ostia (holes) during diastole  Valves in the ostia open and close to regulate flow  The heart is suspended with a series of ligaments  The heart is neurogenic  Contraction in response to signals from nervous system Figure 8.16 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Cardiac Cycle in Arthropods Neurons of cardiac ganglion undergo spontaneous rhythmic depolarization  Cardiomyocytes contract  Volume of heart decreases; pressure increases  Valves in ostia close as pressure increases  Hemolymph leaves the heart via arteries  Stretched ligaments pull apart walls of heart  Volume of heart increases; pressure decreases  Valves in ostia open  Hemolymph is sucked into heart Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Myocardium of Vertebrate Hearts Covered in Mammal Compact YE.EEIEEE qites cardigmm Feedblood endotheliumcells Spongy More spaces Fish and Amphibians mm Figure 8.17 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Vertebrate Hearts  Complex walls with different parts  Pericardium  Sac of connective tissue that surrounds heart  Outer (parietal ) and inner (visceral) layers  Space between layers filled with lubricating (pericardial) fluid  Epicardium (visceral pericardium)  inner layer of the pericardium  continuous with the connective tissue against the heart  Contain nerves that regulate heart and coronary arteries  Myocardium  Layer of heart muscle cells (cardiomyocytes)  Endocardium  Innermost layer of connective tissue covered by endothelial cells (called endothelium) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Myocardium  Two types of myocardium  Compact  Tightly packed cells arranged in regular pattern  Spongy  Meshwork of loosely connected cells  Relative proportions vary among species  Mammals, birds and reptiles  Mostly compact  Fish and amphibians  Mostly spongy  Arranged as trabeculae that extend into chambers Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Fish Hearts  Two chambered heart and two other compartments arranged in series  Sinus venosus  Atrium  Ventricle  Bulbus arteriosus (non contractile) Figure 8.18a Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Cardiac Cycle  Fish hearts  Serial contractions of atrium and ventricle  Valves are passive  Opens and closes according to pressure differences  Assure unidirectional flow of blood  noncontractile bulbus arteriosus serves as volume and pressure reservoir Figure 8.18a Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Amphibian Hearts  Three-chambered heart  Two atria, one ventricle  Trabeculae in ventricle  Helps prevent mixing of oxygenated and deoxygenated blood in ventricle  Spiral fold in conus arteriosus  Helps direct deoxygenated blood to pulmocutaneous circuit and oxygenated blood to systemic circuit Spongy myocardium Figure 8.18b Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Non-Crocodilian Reptile Hearts  Five-chambered heart  Two atria  Three interconnected ventricular compartments  Cavum venosum  Leads to systemic aortas  Cavum pulmonale  Leads to pulmonary artery  Cavum arteriosum  Separation of oxygenated and deoxygenated blood in the ventricle is nearly complete Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Shunting in Reptile Hearts  Can shunt blood to bypass pulmonary or systemic circuit  Right-to-left shunt  Deoxygenated blood bypasses pulmonary circuit and enters systemic circuit  During breath-holding  Left-to-right shunt  Oxygenated blood reenters pulmonary circuit  Aids oxygen delivery to myocardium Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Shunting in Reptile Hearts 2 When it doesn't breath for will it directsblood to systemic circfffftates a brateoxygenfloodsthe heat Figure 8.19a,b Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Crocodilian Reptile Hearts  Four-chambered heart  Two atria  Two ventricles  Complete separation of the chambers Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Birds and Mammals  Four chambers  Two atria  Thin-walled  Two ventricles  Thick-walled  Left ventricle thicker than right  Ventricles separated by intraventricular septum Figure 8.20 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Birds and Mammals  Valves  Atrioventricular (AV) valves 3od I  Between atria and ventricles  Tricuspid on right Ñ  Bicuspid or mitral on left  Semilunar valves  Between ventricles and arteries  Aortic between left ventricle and aorta  Pulmonary between right ventricle and pulmonary artery Figure 8.20 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Hearts  Cardiac cycle – pumping action of the heart  Two phases  Systole  Contraction blood forced into or out of chamber we  Blood is forced out into the circulation  Diastole  Relaxation  Blood enters the heart Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Mammalian Cardiac Cycle  Atria and ventricles alternate systole and diastole  The two atria contract simultaneously  There is a slight pause  The two ventricles contract simultaneously  Atria and ventricles relax while the heart fills with blood Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Mammalian Cardiac Cycle Figure 8.21 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Ventricular Pressure  Left ventricle contracts more forcefully and develops higher pressure  Resistance in pulmonary circuit low due to high capillary density in parallel  Large cross-sectional area  Less pressure needed to pump blood through pulmonary circuit  Low pressure protects delicate blood vessels of lung Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Ventricular Pressures Pulmunary Circuit Systemic Circuit Figure 8.22 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Ventricular Pressures closed Hill, Wyse and Anderson 2008 Animal Physiology 2nd ed Figure 8.22 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Pressure in Vertebrate Circulatory Systems  Blood pressure in left histeson sister ventricle changes with systole and diastole andthe 1st  Pressures decreases as blood moves through system  Pressure and pulse decrease in arterioles due to increase in total cross sectional area S  Velocity of blood highest in arteries, lowest in 8ᵗʰ capillaries, and intermediate in veins Figure 8.33 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Mean Arterial Pressure (MAP)  Average arterial pressure in aorta over time  MAP = 2/3 diastolic pressure + 1/3 systolic pressure Table 8.2 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Blood Velocity  Flow (Q)  Volume of fluid transferred per unit time  Velocity  Distance per unit time  Blood velocity = Q/A  A = cross-sectional area of the vessels  Velocity of flow is inversely related to total cross-sectional area  For example, total cross-sectional area of capillaries is very large  velocity is slow  allowing for more diffusion Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Vasoconstriction Affects Flow & Resistance Law of bulk flow: Q = ΔP/R Q = flow; ΔP = pressure drop; R = resistance R = 8Lη /(r4) L = length of the tube η = viscosity of the fluid r = radius of the tube Poiseuille’s equation: Q = ΔP r4 / (8Lη)  Pressure is the primary driving force for blood flow through organs  Vasoconstriction and vasodilation  small changes in radius – large changes in resistance and flow Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Factors Enhancing Diffusion across Capillaries Diffusion Rate=C · A· D / X (Fick's law of diffusion) C concentration gradient; A surface area; D diffusion coefficient; X distance  capillaries facilitate diffusion of substances from RBCs  capillary walls are thin < 1 um  capillary diameter is 7 um while RBC is 8 um  RBC squeeze through in single file  Blood velocity is slow in capillaries Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Summary heart structure cardiac cycle pressure in circulatory system bulk flow, pressure, resistance modeling of blood vessels as resistors capillaries facilitate diffusion Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Circulatory System - Part 3 We acknowledge and respect the lək̓ʷəŋən peoples on whose traditional territory the university stands and the Songhees, Esquimalt and W ̱ SÁNEĆ peoples whose historical relationships with the land continue to this day. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Blood Velocity  Flow (Q)  Volume of fluid transferred per unit time  Velocity  Distance per unit time  Blood velocity = Q/A  A = cross-sectional area of the vessels  Velocity of flow is inversely related to total cross-sectional area  For example, total cross-sectional area of capillaries is very large  velocity is slow  allowing for more diffusion Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Vasoconstriction Affects Flow & Resistance Law of bulk flow: Q = ΔP/R Diameter of the blood vessels has a great effect on the blood flow to the circulatory system Q = flow; ΔP = pressure drop; R = resistance He is having trouble with his presentation R = 8Lη /(r4) L = length of the tube Blood flow= pressure change η = viscosity of the fluid divided by resistance Resistance decreasing= greater r = radius of the tube blood flow Poiseuille’s equation: Q = ΔP r4 / (8Lη)  Pressure is the primary driving force for blood flow through organs  Vasoconstriction and vasodilation  small changes in radius – large changes in resistance and flow Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Factors Enhancing Diffusion across Capillaries Diffusion Rate=C · A· D / X (Fick's law of diffusion) C concentration gradient; A surface area; D diffusion coefficient; X distance  capillaries facilitate diffusion of substances from RBCs  capillary walls are thin < 1 um  capillary diameter is 7 um while RBC is 8 um  RBC squeeze through in single file  Blood velocity is slow in capillaries Circulatory system delivers O2 and nutrients to the tissues, this Capillaries diameter is less than the happens at a capillary level diameter of the RBC Capillary walls are very thinIMG_1441.HEIC Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Control of Contraction  Vertebrate hearts are myogenic  Cardiomyocytes produce spontaneous rhythmic depolarizations  Do not require nerve signal  Cardiomyocytes are electrically coupled via gap junctions to ensure coordinated contractions  Action potential passes directly from cell to cell Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Electrical Induction of Contraction  Pacemaker cardiomyocites that don't contract  Cells in the sinus venosus in fish  Cells in the right atrium of other vertebrates  Sinoatrial (SA) node Atrioventricular Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Pacemaker Cells: Sinoatrial Node hypnotized nucleotide HCN channels cyclic produce IM current Things that take a  Derived from Activated when... long time to Binds to cAMP activate produce a cardiomyocytes Cation Channel Produces slow depolarization phase very wide action potential  Characteristics of pacemaker cells  Small with few myofibrils, chitin mitochondria, or other organelles This would be pacemaker again  Do not contract P If or Ih ↑  Have unstable resting membrane potential depolarization (pacemaker potential) that drifts upwards until it reaches threshold and initiates an action potential  If (funny current or Ih current, inward Na+), T-type Ca2+ channels, L-type Ca2+ channels, no voltage-gated sodium channels Figure 8.23 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  SA node Pacemaker Cell Action Potential L-type Cav They inactivate slowly T-type Cav Kv If or Ih  If (funny current, inward Na+), T-type Ca2+ channels, L-type Ca2+ channels. If or Ih is encoded by the HCN channel. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Increasing Heart Rate Know this one (HCN) Ease Adeng 1 pusher This is the increased one WEEE L This is the regular one Figure 8.24 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Control of Pacemaker Potentials  Increasing heart rate  Norepinephrine released from sympathetic neurons and epinephrine released from the adrenal medulla.  More pacemaker (funny), Ca2+ channels and Kv channels open.  Rate of depolarization, repolarization and frequency of action potentials increase. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Know this one Decreasing Heart Rate (Vagus Nerve) parasympathetic N S GIRK (Kir3) Gβγ betagatna Gai tant Inhibition  Gi pathway also inhibits cAMP and PKA, which results in less activity of If current and less Cav and Kv channel activity.  However, increases GIRK (Kir3) K+ channel activity. Figure 8.25 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Control of Pacemaker Potentials  Decreasing heart rate  Acetylcholine released from parasympathetic neurons (vagal nerve).  Activate GIRK (Kir3) K+ channels.  Pacemaker cells hyperpolarize.  Decrease in If, L-type and T-type Ca2+ channel activity.  Time for depolarization takes longer, frequency of action potentials decreases.  At rest vagal parasympathetic influences is dominant over sympathetic Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Extended Action Potentials in Cardiomyocytes  Action potentials in cardiomyocytes differ from those in skeletal muscle  Plateau phase  Extended depolarization that corresponds to refractory period and lasts as long as the contraction  Caused by Ca2+ entry via L-type channel and slow Kv channels AR  Prevents tetanus Broad I 8 treat Figure 8.26 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Action Potentials in Cardiomyocytes  APs along sarcolemma signal contraction  Na+ enters cell when Na+ channels open  Depolarization  L-type voltage-gated Ca2+ channels open  Increase in cytoplasmic [Ca2+]  Na+ channels inactivate  K+ leave cell when K+ channels open  Repolarization  Reestablishment of ion gradients by Na+/K+ ATPase and Ca2+ ATPase Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Effects of Norepinephrine on Cardiomyocytes  Nervous and endocrine systems can cause the heart to contract more forcefully and pump more blood with each beat Know this one Figure 8.30 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Conducting Pathways  Modified cardiomyocytes  Cells with elongated, pale appearance  Do not contract  Spread action potential rapidly throughout myocardium  Can undergo rhythmic depolarizations Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Conducting Pathways in Mammalian Heart Figure 8.27 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Electrocardiogram (ECG or EKG) https://www.nyp.org/healthlibrary/multimedia/electrocardiogram-and-electrode-placement Figure 8.28 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Electrocardiogram (ECG or EKG)  Composite recording of action potentials in cardiac muscle  P wave  Atrial depolarization  wave of depolarization from SA node throughout atria  QRS complex  Ventricular depolarization  ST segment corresponds to plateau phase of ventricular action potential  T wave  Ventricular repolarization  Used for clinical diagnosis of problems with conducting system; arrhythmias of the heart Figure 8.28 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Cardiac Output  Cardiac output (CO)  Volume of blood pumped per unit time  CO = HR  SV  HR = Rate of contraction (beats per minute)  Stroke volume (SV)  Volume of blood pumped with each beat  stroke volume = end diastolic volume – end systolic volume  Look up the heart rates of different animals: human, blue whale, frog, mouse, cat, elephant, rat, reptile Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Cardiac Output Nervous to End of circulatory for the exam CO = HR  SV  Cardiac output can be modified by regulating heart rate and/or stroke volume  Heart rate  Modulated by autonomic nerves and adrenal medulla  Decreased HR (bradycardia)  Increased HR (tachycardia)  Stroke volume  Modulated by various nervous, hormonal, and physical Greater cardiac factors Parasympathetic blood output when exercising and sympathetic systems Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Control of Stroke Volume  Frank-Starling effect  Increased end-diastolic volume results in a more forceful contraction and increased SV  Length-tension relationship for muscle  Heart automatically compensates for increases in volume of blood returning to the heart (autoregulation) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Control of Stroke Volume Level of sympathetic activity shifts the position of the cardiac muscle length-tension relationship Figure 8.31b Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Summary heart structure cardiac cycle pressure in circulatory system electrical activity of the heart regulation of heart contraction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Circulatory System - Part 4 We acknowledge and respect the lək̓ʷəŋən peoples on whose traditional territory the university stands and the Songhees, Esquimalt and W ̱ SÁNEĆ peoples whose historical relationships with the land continue to this day. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Homeostatic Regulation of Blood Pressure  Pressure is the primary driving force for blood flow through organs  MAP = CO  TPR  Body varies cardiac output (CO) and total peripheral resistance (TPR) to maintain a mean arterial pressure (MAP) within a set range Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Cardiac Output  Cardiac output (CO)  Volume of blood pumped per unit time  CO = HR  SV  Rate of contraction (beats per minute)  Stroke volume (SV)  Volume of blood pumped with each beat  stroke volume = end diastolic volume – end systolic volume Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Cardiac Output CO = HR  SV  Cardiac output can be modified by regulating heart rate and/or stroke volume (chronotropy, inotropy)  Heart rate  Modulated by autonomic nerves and adrenal medulla  Decreased HR (bradycardia)  Increased HR (tachycardia)  Stroke volume  Modulated by various nervous, hormonal, and physical factors Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Increasing Heart Rate E page (HCN channel) A Regulatedbyhormones Figure 8.24 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Decreasing Heart Rate (Vagus Nerve) GIRK (Kir3) Gβγ tors No Entities  Gi pathway also inhibits cAMP and PKA, which results in less activity of If current and less Cav and Kv channel activity.  However, increases GIRK K+ channel activity. Figure 8.25 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Effects of Norepinephrine on Cardiomyocytes  Nervous and endocrine systems can cause the heart to contract more forcefully and pump more blood with each beat Figure 8.30 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Control of Stroke Volume  Frank-Starling effect  Increased end-diastolic volume results in a more forceful contraction and increased SV  Length-tension relationship for muscle  Heart automatically compensates for increases in volume of blood returning to the heart (autoregulation) Figure 8.31a Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Control of Stroke Volume Level of sympathetic activity shifts the position of the cardiac muscle length-tension relationship Autonomic NS Regulates Figure 8.31b Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Homeostatic Regulation of Blood Pressure  Pressure is the primary driving force for blood flow through organs  MAP = CO  TPR  Body varies cardiac output (CO) and total peripheral resistance (TPR) to maintain a near constant mean arterial pressure (MAP) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Regulation of Blood Flow Law of bulk flow: Q = ΔP/R Q = flow; ΔP = pressure drop; R = resistance R = 8Lη /r4 L = length of the tube η = viscosity of the fluid r = radius of the tube Poiseuille’s equation: Q = ΔP r4 / 8Lη Δ  Pressure is the primary driving force for blood flow through organs  Vasoconstriction and vasodilation  small changes in radius – large changes in resistance and flow Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Regulation of Blood Flow  Arterioles control blood distribution  Because arterioles are arranged in parallel, they can alter blood flow to various organs  Vasoconstriction and vasodilation  Changes in resistance alter flow  Control of vasoconstriction and vasodilation  Autoregulation capillaries  Direct response of the arteriole smooth muscle  Intrinsic factors Metabolic  Metabolic state of the tissue  Extrinsic factors autonomicnervous system hormones  Nervous and endocrine systems Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Myogenic Autoregulation of Flow  Myogenic autoregulation - some smooth muscle cells in arterioles are sensitive to stretch and contract when blood pressure increases  Acts as negative feedback loop  Prevents excessive flow of blood into tissue Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Metabolic Activity of Tissues  Smooth muscle cells in arterioles sensitive to conditions of extracellular fluid  Levels of metabolites alter vasoconstriction/vasodilation  Blood flow matched to metabolic requirements  exercise – decrease O2, increase CO2 – vasodilation  paracrine – nitric oxide - 59 or vasodilation the S Figure 8.32 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Neural and Endocrine Control of Flow Autonomic  Norepinephrine from sympathetic neurons causes vasoconstriction of arterioles except skeletal muscle limiting  Decreased blood flow sympathetic tone causes vasodilation  In skeletal muscle and heart – NE/E causes vasodilation  Other hormones affect vascular smooth muscle  Vasopressin (ADH) from the posterior pituitary causes generalized vasoconstriction water salt uptake 555 1  Angiotensin II produced in response to decreased blood pressure causes generalized vasoconstriction 15kt  Atrial natriuretic peptide (ANP) produced in response decrees to increased blood pressure promotes generalized MA vasodilation mastitis parasympathetic Salivary gland System gastrointestinal tract Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Homeostatic Regulation of Blood Pressure  Pressure is the primary driving force for blood flow through organs  MAP = CO  TPR ooo  Body varies cardiac output (CO) and total peripheral resistance (TPR) to maintain a near constant mean arterial pressure (MAP) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Homeostatic Regulation of Blood Pressure Totithistace somey cordiforut here suffaine iiiIEEE vasoconstriction slows Ilation speedsup vasodilation Figure 8.37 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Baroreceptor Reflex  Baroreceptors  Stretch-sensitive mechano- receptors are in walls of many major blood vessels Stretch  Especially carotid arteries and aorta  Send nerve signals to medulla oblongata (cardiovascular control center)  Baroreceptor reflex regulates MAP MAR 3 Parasympathetic MA3 Figure 8.38 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Baroreceptor Reflex wall on Artery Whenit purses duty it excersize response triggers Resulating MAR Figure 8.38 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Summary heart rate and contractility increased with beta1 adrenergic and inhibited by muscarinic receptors mean arterial pressure also maintained by vasoconstriction myogenic control metabolites and paracrine sympathetic nervous system hormones – vasopressin, angiotensin II, ANP 40 min 28 Q mechanoreceptors todays lecture NS Lecture 2 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings