Presentation on theme: "The heart circulates blood to every tissue and organ, sustaining all bodily strength anphys-opener-23-0.jpg."— Presentation transcript:
1The heart circulates blood to every tissue and organ, sustaining all bodily strength anphys-opener-23-0.jpg
2Functions of the Circulatory System Transportation:Respiratory:Transport 02 and C02.Nutritive:Carry absorbed digestion products to liver and to tissues.Excretory:Carry metabolic wastes to kidneys to be excreted.
3Functions of the Circulatory System (continued) Regulation:Hormonal:Carry hormones to target tissues to produce their effects.Temperature:Divert blood to cool or warm the body.Protection:Blood clotting.Immune:Leukocytes, cytokines and complement act against pathogens.
4Components of Circulatory System Components of Cardiovascular system (CV):Heart:Pumping action creates pressure head needed to push blood through vessels.Blood vessels:Permits blood flow from heart to cells and back to the heart.Arteries, arterioles, capillaries, venules, veins.Lymphatic System:Lymphatic vessels transport interstitial fluid.Lymph nodes cleanse lymph prior to return in venous blood.
6Composition of Blood Composition of blood Plasma: Plasma proteins: Straw-colored liquid.Consists of H20 and dissolved solutes.Ions, metabolites, hormones, antibodies.Na+ is the major solute of the plasma.Plasma proteins:Constitute 7-9% of plasma.Albumin:Accounts for 60-80% of plasma proteins.Provides the colloid osmotic pressure needed to draw H20 from interstitial fluid to capillaries.Maintains blood pressure.
7Composition of the Blood (continued) Composition of blood:Plasma proteins (continued):Globulins:a globulin:Transport lipids and fat soluble vitamins.b globulin:g globulin:Antibodies that function in immunity.Fibrinogen:Constitutes 4% of plasma proteins.Important clotting factor.Converted into fibrin during the clotting process.
8Composition of the Blood (continued) Composition of bloodSerum:Fluid from clotted blood.Does not contain fibrinogen.Plasma volume:Number of regulatory mechanisms in the body maintain homeostasis of plasma volume.Osmoreceptors.ADH.Renin-angiotensin-aldosterone system.
10Erythrocytes Flattened biconcave discs. Provide increased surface area through which gas can diffuse.Lack nuclei and mitochondria.Half-life ~ 120 days.Each RBC contains 280 million hemoglobin with 4 heme chains (contain iron).Removed from circulation by phagocytic cells in liver, spleen, and bone marrow.
11Leukocytes: Contain nuclei and mitochondria. Move in amoeboid fashion. Can squeeze through capillary walls (diapedesis).Almost invisible, so named after their staining properties.Granular leukocytes:Help detoxify foreign substances.Release heparin.Agranular leukocytes:Phagocytic.Produce antibodies.
12Platelets (thrombocytes) Smallest of formed elements.Are fragments of megakaryocytes.Lack nuclei.Capable of amoeboid movement.Important in blood clotting:Constitute most of the mass of the clot.Release serotonin to vasoconstrict and reduce blood flow to area.Secrete growth factors:Maintain the integrity of blood vessel wall.Survive 5-9 days.
13HematopoiesisHematopoiesusUndifferentiated cells gradually differentiate to become stem cells, that form blood cells.Occurs in myeloid tissue (bone marrow of long bones) and lymphoid tissue.2 types of hematopoiesis:Erythropoiesis:Formation of RBCs.Leukopoiesis:Formation of WBCs.
15Figure 23.14 The circulatory plan in gill-breathing fish (Part 2) anphys-fig jpg
16Figure 23.22 Circulation through the body of a crayfish or lobster (Part 1) anphys-fig jpg
17Figure 23.18 Blood flow in heart ventricles and systemic and pulmonary arteries of crocodilians anphys-fig jpg
18Pulmonary and Systemic Circulations Pulmonary circulation:Path of blood from right ventricle through the lungs and back to the heart.Systemic circulation:Oxygen-rich blood pumped to all organ systems to supply nutrients.Rate of blood flow through systemic circulation = flow rate through pulmonary circulation.
19Figure 23.10 The circulatory plan in mammals and birds (Part 1) anphys-fig jpg
20Figure 23.10 The circulatory plan in mammals and birds (Part 2) anphys-fig jpg
21Figure 23.14 The circulatory plan in gill-breathing fish (Part 1) anphys-fig jpg
22Figure 23.15 The circulatory plans of some air-breathing fish (Part 1) anphys-fig jpg
23Figure 23.15 The circulatory plans of some air-breathing fish (Part 2) anphys-fig jpg
24Figure 23.16 The branchial vascular arches of a lungfish anphys-fig jpg
25Figure 23.19 The circulatory plan of squids and octopuses (Part 1) anphys-fig jpg
26Figure 23.22 Circulation through the body of a crayfish or lobster (Part 2) anphys-fig jpg
27Box 23.3 Blood flow through the tissues of an insect is principally through lacunae and sinuses anphys-box jpg
28Conducting Tissues of the Heart Contracting tissues of the heart:APs spread through myocardial cells through gap junctions.Impulses cannot spread to ventricles directly because of fibrous tissue.Conduction pathway:SA node.AV node.Bundle of His.Purkinje fibers.Stimulation of Purkinje fibers cause both ventricles to contract simultaneously.
30Conduction of ImpulseConduction of impulseAPs from SA node spread quickly at rate of m/sec.Time delay occurs as impulses pass through AV node.Slow conduction of 0.03 – 0.05 m/sec.Impulse conduction increases as spread to Purkinje fibers at a velocity of 5.0 m/sec.Ventricular contraction begins 0.1–0.2 sec. after contraction of the atria.
31Heart contracts as syncytium. Contraction lasts almost 300 msec. Refractory PeriodsRefractory periods:Heart contracts as syncytium.Contraction lasts almost 300 msec.Refractory periods last almost as long as contraction.Myocardial muscle cannot be stimulated to contract again until it has relaxed.Summation cannot occur.
32Excitation-Contraction Coupling in Heart Muscle Depolarization of myocardial cell stimulates opening of VG Ca2+ channels in sarcolema.Ca2+ diffuses down gradient into cell.Stimulates opening of Ca2+-release channels in SR.Ca2+ binds to troponin and stimulates contraction (same mechanisms as in skeletal muscle).During repolarization Ca2+ actively transported out of the cell via a Na+-Ca2+- exchanger.
33Electrocardiogram (ECG/EKG) EKG (ECG)The body is a good conductor of electricity.Tissue fluids have a high [ions] that move in response to potential differences.Electrocardiogram:Measure of the electrical activity of the heart per unit time.Potential differences generated by heart are conducted to body surface where they can be recorded on electrodes on the skin.Does NOT measure the flow of blood through the heart.
34ECG leads Bipolar leads: Unipolar leads: Record voltage between electrodes placed on wrists and legs.Right leg is ground.Unipolar leads:Voltage is recorded between a single “exploratory electrode” placed on body and an electrode built into the electrocardiograph.Placed on right arm, left arm, left leg, and chest.Allow to view the changing pattern of electrical activity from different perspectives.
35Figure 23.4 The conducting system and the process of conduction in the mammalian heart (Part 1) anphys-fig jpg
36Figure 23.4 The conducting system and the process of conduction in the mammalian heart (Part 2) anphys-fig jpg
37Figure 23.4 The conducting system and the process of conduction in the mammalian heart (Part 3) anphys-fig jpg
42Figure 23.2 The heart as a pump: The dynamics of the left side of the human heart anphys-fig jpg
43Figure 23.2 The heart as a pump: The dynamics of the left side of the human heart (Part 1) anphys-fig jpg
44Cardiac Cycle (continued) Step 1: Isovolumetric contraction:QRS just occurred.Contraction of the ventricle causes ventricular pressure to rise above atrial pressure.AV valves close.Ventricular pressure is less than aortic pressure.Semilunar valves are closed.Volume of blood in ventricle is EDV.Step 2: Ejection:Contraction of the ventricle causes ventricular pressure to rise above aortic pressure.Semilunar valves open.Ventricular pressure is greater than atrial pressure.AV valves are closed.Volume of blood ejected: SV.
45Cardiac Cycle (continued) Step 3: T wave occurs:Ventricular pressure drops below aortic pressure.Step 4: Isovolumetric relaxation:Back pressure causes semilunar valves to close.AV valves are still closed.Volume of blood in the ventricle: ESV.Step 5: Rapid filling of ventricles:Ventricular pressure decreases below atrial pressure.AV valves open.Rapid ventricular filling occurs.
46Figure 23.2 The heart as a pump: The dynamics of the left side of the human heart (Part 2) anphys-fig jpg
47Figure 23.3 Four systems evolved by animals to supply O2 to the myocardium (Part 1) anphys-fig jpg
48Figure 23.3 Four systems evolved by animals to supply O2 to the myocardium (Part 2) anphys-fig jpg
49Figure 23.7 Fluid-column effects on blood pressure in the arterial vascular system anphys-fig jpg
50Figure 23.8 Total fluid energy: The true driving force for blood flow anphys-fig jpg
51Figure 23.9 The physics of flow through tubes anphys-fig jpg
52Figure 23.11 A microcirculatory bed anphys-fig jpg
53Figure 23.12 Blood flow in the human systemic vasculature (Part 1) anphys-fig jpg
54Figure 23.12 Blood flow in the human systemic vasculature (Part 2) anphys-fig jpg
59Maintaining Blood Pressure Maintaining blood pressure requires:Cooperation of the heart, blood vessels, and kidneysSupervision of the brain
60Maintaining Blood Pressure The main factors influencing blood pressure are:Cardiac output (CO)Peripheral resistance (PR)Blood volumeBlood pressure = CO x PRBlood pressure varies directly with CO, PR, and blood volume
62Cardiac Output (CO)Cardiac output is determined by venous return and neural and hormonal controlsResting heart rate is controlled by the cardioinhibitory center via the vagus nervesStroke volume is controlled by venous return (end diastolic volume, or EDV)Under stress, the cardioacceleratory center increases heart rate and stroke volumeThe end systolic volume (ESV) decreases and MAP increases
65Controls of Blood Pressure Short-term controls:Are mediated by the nervous system and bloodborne chemicalsCounteract moment-to-moment fluctuations in blood pressure by altering peripheral resistanceLong-term controls regulate blood volume
66Short-Term Mechanisms: Neural Controls Neural controls of peripheral resistance:Alter blood distribution in response to demandsMaintain MAP by altering blood vessel diameterNeural controls operate via reflex arcs involving:BaroreceptorsVasomotor centers and vasomotor fibersVascular smooth muscle
67Short-Term Mechanisms: Vasomotor Center Vasomotor center – a cluster of sympathetic neurons in the medulla that oversees changes in blood vessel diameterMaintains blood vessel tone by innervating smooth muscles of blood vessels, especially arteriolesCardiovascular center – vasomotor center plus the cardiac centers that integrate blood pressure control by altering cardiac output and blood vessel diameter
68Short-Term Mechanisms: Vasomotor Activity Sympathetic activity causes:Vasoconstriction and a rise in BP if increasedBP to decline to basal levels if decreasedVasomotor activity is modified by:Baroreceptors (pressure-sensitive), chemoreceptors (O2, CO2, and H+ sensitive), higher brain centers, bloodborne chemicals, and hormones
69Short-Term Mechanisms: Baroreceptor-Initiated Reflexes Increased blood pressure stimulates the cardioinhibitory center to:Increase vessel diameterDecrease heart rate, cardiac output, peripheral resistance, and blood pressure
70Short-Term Mechanisms: Baroreceptor-Initiated Reflexes Declining blood pressure stimulates the cardioacceleratory center to:Increase cardiac output and peripheral resistanceLow blood pressure also stimulates the vasomotor center to constrict blood vessels
72Dehydration or excess salt intake: Regulation by ADHReleased by posterior pituitary when osmoreceptors detect an increase in plasma osmolality.Dehydration or excess salt intake:Produces sensation of thirst.Stimulates H20 reabsorption from urine.
73Chemicals that Decrease Blood Pressure Atrial natriuretic peptide (ANP) – causes blood volume and pressure to declineNitric oxide (NO) – is a brief but potent vasodilatorInflammatory chemicals – histamine, prostacyclin, and kinins are potent vasodilatorsAlcohol – causes BP to drop by inhibiting ADH
74Long-Term Mechanisms: Renal Regulation Long-term mechanisms control BP by altering blood volumeBaroreceptors adapt to chronic high or low BPIncreased BP stimulates the kidneys to eliminate water, thus reducing BPDecreased BP stimulates the kidneys to increase blood volume and BP
75Kidney Action and Blood Pressure Kidneys act directly and indirectly to maintain long-term blood pressureDirect renal mechanism alters blood volumeIndirect renal mechanism involves the renin-angiotensin mechanism
76Kidney Action and Blood Pressure Declining BP causes the release of renin, which triggers the release of angiotensin IIAngiotensin II is a potent vasoconstrictor that stimulates aldosterone secretionAldosterone enhances renal reabsorption and stimulates ADH release
77Renin-Angiotension-Aldosterone System (continued)
78Diving physiology part 1 The oxygen store of diversAdjustment of circulatory functionCNS and heart dependent on aerobic catabolism for ATP productionSkeletal muscle tolerant of O2 deprivationBlood flow to skin, gut, kidneys is curtailed by vasoconstrictionOxygen deprived tissue will turn to anaerobic catabolismLactic acid accumulates
79Diving physiology part 2 The amount of O2 stored in blood depends on:O2 carrying capacity of the bloodVolume of bloodDegree of saturation of blood with O2 at the time of submergence
80Thoracic cavity and lungs-- compressible High myoglobin concentrations Diving physiologyThoracic cavity and lungs-- compressibleHigh myoglobin concentrationsIn skeletal muscleLarge myoglobin-bound O2 storesO2 remains bound to the myoglobin until the O2 partial pressure in the muscles falls to a low level
81Circulatory adjustment during dives BradycardiaDrop in cardiac outputWeddell seals show an 86% drop in cardiac work and an 85% reduction in blood flow to their ventricular heart muscleRegional vasoconstrictionBecomes a “heart-lung-brain” machineLarge concentration of rbcs in their blood when they are divingRbcs stored in their spleen- release during dive
82Metabolism during dives 3 factors determine the limits of endurance of the O2 –dependent tissuesMagnitude of O2 store availableRate of use of the O2 storeExtent to which P02 can fall before impairing the function of O2-dependent tissuesMR during dive is the most important factor in determining metabolic limits on dive durationlow MR, slow O2 depletion, and slow lactic acid accumulation
83Prolong dive has major behavioral consequences The aerobic dive limitProlong dive has major behavioral consequencesRequires time for ridding body of lactic acidMust stay at the water’s surface where it can breatheLactic acid burdens of successive divesAdditiveExample- a seal that accumulates 80 ml lactic acid/ 100 ml of blood has to remain at the surface over an hour to return its lactic acid to resting level
84Decompression sickness (DS) Caused by N2 absorption from a compressed-air sourceStart of dive– tissue contains a [N2]DS occur after a long deep dive and then surfaces suddenlyPN2 pressure falls in the lungs to its ordinary valueN2-charged blood and other tissues start to lose N2 in the lung airBubbles of blood may form within the blood and tissues
85Decompression sickness (DS) 2 Breath-hold dives must be repeated many times to cause DS in humansMarine animals avoid DS during deep dives by alveolar collapseSpecial features of lungs and thoraxKeep pulmonary N2 within lungsAvoid build up in blood and tissuesLung air moves to conducting airways