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This 34 page Class Notes was uploaded by Michelle Ros on Wednesday April 29, 2015. The Class Notes belongs to BIO 126 at Drexel University taught by Dr. Togna & Dr. Smith in Spring2015. Since its upload, it has received 122 views. For similar materials see Physiology and Ecology in Biology at Drexel University.
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Date Created: 04/29/15
BIO 126 WEEK 3 CHAPTER 48 CIRCULATORY SYSTEM POWERPOINT NOTES FUNCTIONS OF THE CIRCULATORY SYSTEM I Moving oxygen to every cell I Getting rid of C02 I Important endocrine component 0 Moves hormones I Functions of circulating blood 0 Transportation I Ions nutrients 0 Regulation I Hormones 0 Protection I Platelets BLOOD I Type of connective tissue composed of 0 Fluid matrix called plasma 0 Formed elements I Platelets I Cell fragments that pinch off from larger cells in the bone marrow I Function in the formation of blood clots I Hemotopoiesis 0 Blood cell production 0 Develop from pluripotent stem cells 0 Occurs in bone marrow I Lymphoid stem cell I Lymphocytes I Myeloid stem cell I All other blood cells 0 Erythroprotein stimulates the production of erythrocytes I 92 water I Solutes O Nutrients waste hormones O Ions 0 Proteins I Albumin I Alpha and beta globulins I Fibronigen B10 126 WEEK 3 0 If removed I plasma serum 0 Red blood cells erythrocytes I In vertebrates I contains hemoglobin I Mature mammalian RBC no nuclei 0 White blood cells I Larger than RBC contain nuclei I Can migrate out of capillaries into tissue uid I Types 0 Granular leukocytes O Neutrophils eosinophils basophils 0 Angular leukocytes O Monocytes and lymphocytes TYPES OF CIRCULATORY SYSTEMS I No separate circulatory system 0 Sponges circulate water using many incurrent pores and one excurrent pore O Cnidarian circulate water through a gastrovascular cavity also used for digestion O Nematodes are thin enough that the digestive tract can also be used as circulatory system 0 Open circulatory system 0 No distinction between circulating and extracellular uid 0 Fluid hemolymph 0 Closed circulatory system 0 Distinct circulatory uid enclosed in blood vessels and transported away from and back to the heart VERTEBRATE CIRCULATORY SYSTEMS 0 Fishes O Evolved a true chamberpump heart 0 Four structures are arrayed after the other to form two pumping chambers I First chamber sinus venosus and atrium I Second chamber ventricle and conus arteriosus I Contract in the order listed M I SV I A I V I CA 0 Blood is pumped through the gills then to the rest of the body 0 Amphibians O Advent of lungs required a second pumping circuit I double circulation I Pulmonary circulation 0 Moves blood between the heart and lungs I Systemic circulation 0 Moves blood between the heart and the rest of the body B10 126 WEEK 3 O 3chambered heart I 2 atria I 1 ventricle 0 Separation of the pulmonary and systemic circulations is incomplete 0 Amphibians living in water obtain additional oxygen by diffusion through their skin 0 Reptiles 0 Septum I Partially divides the ventricle I Reduces mixing of blood in the heart 0 Mammals birds crocodilians 0 4 chambered hearts I Right atrium 0 Receives deoxygenated blood from the body and delivers it to the right ventricle Which pumps it to the lungs I Left atrium 0 Receives oxygenated blood from the lungs and delivers it to the left ventricle pumps it to the rest of the body I Left ventricle I Right ventricle O Atrioventricular valve AV valves I Maintain unidirectional blood ow between atria and ventricles I Tricuspid valve on the right I BicuspidMitral valve on the left 0 Semilunar valve I Ensure the oneway ow out o the ventricles to the arterial systems I Pulmonary valve located at the exit of the right ventricles I Aortic valve located at the exit of the left ventricle CARDIAC CYCLE I Valves open and close as the heart goes through the cardiac cycle I Ventricles relaxed and filling diastole I Ventricles contracted and pumping systole Lubdub sounds heard With stethoscope O Lub AV valves closing 0 Dub closing of semilunar valves ELECTROPHYSIOLOGY I Heart contains selfexcitable autorhythmic fibers 0 Muscle fiber 1 cell 0 Most important s sinoatrial node SA 0 Located in wall of right atrium O Acts as pacemaker BIO 126 WEEK 3 O Autonomic nervous system can modulate rate I Sympathetic and parasympathetic divisions O Depolarized SA I To left atrium I To right atrium and atrioventricular node 0 AV node is only pathway for conduction to ventricles I Spreads through atrioventricular bundle I Purkinje fibers I Directly stimulate the myocardial cells of both ventricles to contract 0 EKG electrocardiogram 0 First peak P produced by depolarization of atria atrial systole 0 Second peak QRS produced by ventricular depolarization ventricular systole 0 Last peak T is produced by repolarization of ventricles ventricular diastole BLOOD FLOW 0 Arteries 0 Conduct blood away from the heart 0 Layers of smooth muscle and connective tissue around smooth endothelium 0 Arterioles 0 Can dilate or constrict to control blood distribution to tissues 0 Capillaries 0 Site of gas and nutrientwaste exchange singlecelled layer of endothelium on a basement membrane 0 Continuous capillaries have smooth walls 0 Fenestrated capillaries have openings or fenestrations O Smallest and narrowest vessels in the body I Venules 0 Small thin extensions of capillaries I Veins 0 Conduct blood back to the heart 0 Thinner and less muscular than arteries 0 Need help returning blood to the heart I Smooth muscle contractions help propel blood I Valves inside veins squeezed by skeletal muscles BLOOD PRESSURE FLOW AND RESISTANCE 0 Blood pressure 0 Force exerted by blood on the walls of the blood vessels I Higher in arteries than veins BIO 126 WEEK 3 Resistance R O Tendency of blood vessels to slow down the ow of blood I Based on vessel radius length and blood viscosity 0 Change in arteriolar resistance is a major mechanism to control blood ow to a region 0 Radius is the most important factor I Vasodilation increase in radius I Vasoconstriction decrease in radius I Important factors in regulating blody heat in both ectotherms and endotherms O Controlled by locally produced substances hormones and nervous system input BLOOD FLOW AND BLOOD PRESSURE Baroreceptor re ex O Negative feedback loop that responds to blood pressure changes 0 Baroreceptors detect changes in arterial blood pressure 0 If blood pressure decreases the number of impulses to cardiac center is decreased I Ultimately resulting in blood pressure increase 0 If blood pressure increases the number of impulses to cardiac center is increased I Ultimately resulting in blood pressure decrease Autonomic nervous system modulates heart rhythm and force of contraction Cardiac center of the medulla oblongata moderates heart rate 0 Norepinephrine sympathetic neurons increases heart rate 0 Acetylcholine parasympathetic neurons decreases heart rate Blood pressure increases With blood volume Blood volume is regulated by four hormones O Antidiuretic hormone O Aldosterone O Atrial natriuretic hormone O Nitric oxide LYMPHATIC SYSTEM Significant amount of water and solutes in the blood plasma filter through the walls of the capillaries to form the interstitial uid Most uid leaves at the arteriole end of the capillary and returns at the venule end Fluid that does not return to capillaries is returned to circulation by the lymphatic system Vascular system that collects uid and returns it to the blood Fluid is monitored for pathogens by immune system cells as it travels B10 126 WEEK 3 0 Consists of lymphatic capillaries lymphatic vessels lymph nodes and lymphatic organs spleen and thymus 0 Excess uid in the tissues drains into blindended lymph capillaries 0 Lymph passes into progressively larger vessels With oneway valves 0 Eventually drains into subclavian veins BIO 126 WEEK 3 CHAPTER 49 THE CIRCULATORY SYSTEM LEARNING OBJECTIVE NOTES 491 The Components of Blood 1 Describe the functions of circulating blood a Transportation i Essential substances for metabolism are transported by blood ii Red blood cells 1 Transport oxygen attached to hemoglobin iii Plasma 1 Nutrients are transported b Regulation i Transportation of regulatory hormones from the endocrine glands ii Temperature regulation 1 Contraction and dilation of blood vessels near the surface of the body c Protection i Protects against injury and foreign microbes or toxins introduced into the body ii Blood clotting 1 Prevent blood loss iii White blood cellsleukocytes 1 Disarm invaders viruses and bacteria 2 Distinguish between the types of formed elements a Components of blood plasma minus the 92 water i Nutrients wastes hormones 1 Nutrients from digestive breakdown that can be used by cells amino acids vitamins 2 Wastes nitrogen compounds CO2 produced ii Ions 1 Na Cl HCO3 iii Proteins l Albumin a Constitutes most of the plasma proteins 2 Globulins a Alpha and beta b Lipid carriers c Steroid carriers 3 Fibrinogen a Required for blood clotting b Blood containing fibrinogen that is removed serum b Circulating cells and platelets BIO 126 WEEK 3 i Red blood cellserythrocytes 1 Hematocrit a Total blood volume that is occupied 2 Donutshaped disk with central depression that does not go all the way through Mature mammalian erythrocytes lack nuclei 4 Vertebrate erythrocytes contain hemoglobin a Binds and transports oxygen i Invertebrates I present in plasma b Found only in erythrocytes ii White blood cells leukocytes 1 Larger than red blood cells 2 Contain nuclei 3 Not confined to the blood a Migrate out of capillaries through intercellular spaces into surrounding interstitial uid 4 Each has a specific role in defending against invading microorganisms and other foreign substances a Granular leukocytes i Include neutrophils eosinophils and basophils 1 Named according to staining properties of granules in cytoplasm 2 Most common neutrophils lymphocytes monocytes eosinophils basophils b Nongranular leukocyte i Include monocyte lymphocytes 9 iii Platelets 1 Cell fragments that pinch off from larger cells in the bone marrow 2 Liver releases thrombin into blood 3 Fibrinogen is converted into insoluble threads of fibrin a Forms clots iv Formed elements arise from stem cells 1 Pluripotent stem cells a Production of blood cells i Bone marrow red blood cells ii Hematopoiesis red blood cells 1 Generates two types of stem cells with a more restricted fate iii Lymphoid stem cells gives rise to lymphocytes B10 126 WEEK 3 iv Myeloid stem cells gives rise to the rest of the blood cells 2 Hormones a Erythropoietin i Stimulates production of erythrocytes from the myeloid stem cells 1 erythropoiesis 3 Delineate the process of blood clotting a Smooth muscle in vessel walls contract I constriction of blood vessels b Platelets accumulate at injured site and form a plug by sticking to one another and surrounding tissue c Enzymatic reactions triggered by platelets plasma factors and molecules released from the damaged tissue i Comes out of solution in a rxn that forms fibrin d Reinforced by fibrin threads constitutes blood clot B10 126 WEEK 3 492 Invertebrate Circulatory Systems 1 Distinguish between open and closed circulatory systems a Open circulatory system i Oneway path ii Found in most mollusks and in arthropods 1 No distinction between circulating uid and extracellular uid hemolymph iii Pump hemolymph into tissues from which it then drains into a central cavity iV Heart pumps hemolymph through channels in the body b Closed circulatory system i Move uids in a loop ii Circulating uid blood always enclosed within blood vessels that transport it away from and back to the heart iii A11 vertebrates iV Blood pushed through five small connecting arteries act as pumps to a ventral vessel transports blood posteriorly until it eventually reenters the dorsal vessel V Supply tissues with oxygen and nutrients and remove waste products Vi Move uid in a loop to and from a muscular pumping region such as the heart 2 Define hemolymph a Circulating uid and extracellular uid of body tissues b In invertebrates identical to extracellular uid B10 126 WEEK 3 493 Vertebrate Circulatory Systems 1 Trace the evolution of the chambered heart from lancelets to birds and mammals a Lancelets i Simple tubular hearts ii Little more than a specialized zone of the ventral artery that was more heavily muscled than the rest of the arteries I contracts in simple peristaltic waves iii Tube with four structures arrayed one after the other to form two pumping chambers 1 First chamber a Sinus venosus i First to contract initiation of contraction ii VERTEBRATES HAVE HOMOLOGOUS STRUCTURE TO THIS sinoatrial node SA b Atrium i Second to contract 2 Second chamber a Ventricles b Conus arteriosus i After this structure I gills 1 Blood becomes oxygenated 2 Blood pressure drops significantly a Slows circulation from the gills to the rest of the body and can limit oxygen delivery to tissues ii Gills I network of arteries 1 Returns back to sinus venosus b Birds and mammals i Four chambered heart with two separate atria and two separate ventricles 1 Right Aatrium a Receives deoxygenated blood from the body and delivers it to the right ventricle 2 Right Ventricle a Pumps blood to lungs 3 Left Atrium a Receives oxygenated blood from the lungs and delivers it to the left ventricle 4 Left ventricle a Pumps oxygenated blood to the rest of the body B10 126 WEEK 3 5 Atriums RECEIVE blood 6 Ventricles PUMP blood ii Two cycle pump 1 More efficient for endothermy 2 Both atria fill with blood and simultaneously contract emptying their blood into the ventricles 3 Both ventricles contract at the same time pushing blood simultaneously into the pulmonary and systemic circulations 2 Delineate the ow of blood through the circulatory system in birds and mammals a Deoxygenated blood travels in the pulmonary circuit from the right atrium into the right ventricle and then to the lungs b Returns to the left atrium c Oxygenated blood travels into systemic circuit from the left atrium into the left ventricle and then to the body d Returns to right atrium 3 Amphibian amp reptile circulatory a Second pumping circuit b Pulmonary arteries heart lungs I doesn t go directly to tissues of body returned via pulmonary veins to heart blood leaves the heart a second time to be circulated through other tissues c Double circulation i One system pulmonary circulation 1 Moves blood between heart and lungs ii Second system systemic circulation 1 Moves blood between the heart and rest of the body d Amphibian circulation i Two structural features that significantly reduce this mixing 1 Atrium a Divided into two chambers i Right atrium receives deoxygenated blood from the systemic circulation ii Left atrium receives oxygenated blood from the lungs iii Two types of blood do not mix in the atria 2 Single ventricle a Separation of pulmonary and systemic circulations is incomplete b Mixing of bloods is reduced 3 Conus arteriosus a Partially separated by a dividing wall i Directs deoxygenated blood into the pulmonary arteries and oxygenated blood B10 126 WEEK 3 into aorta major artery of the systemic circulation 4 Diffusion of oxygen through skin a Pulmocutaneous circuit I cutaneous respiration ii Sends blood to both the lungs and the skin e Reptilian circulation i Two separate atria ii Reptiles have septum that partially subdivides the ventricle 1 Complete in crocodilians a Two separate ventricles divided by a complete septum iii Conus arteriosus has become incorporated into the trunks of the large arteries leaving the heart BIO 126 WEEK 3 494 The FourChambered Heart and the Blood Vessels 1 Explain the cardiac cycle a Two contractions resting period between them i One atrial contraction to send blood to the ventricles ii One ventricular contraction to send blood to the pulmonary and systemic circuits b Drives cardiovascular system i Two pairs of valves 1 Atrioventricular valve AV a Maintains unidirectional blood ow between the atria and ventricles b Right AV valve tricuspid valve c Left AV valve bicuspid valve mitral valve 2 Semilunar valves a Ensure oneway ow out of the ventricles to the arterial systems 3 Pulmonary valves a Located at the exit of the right ventricle b Open and close as the heart goes through its cycle 4 Aortic valve a Located at the exit of the left ventricle b Open and close as the heart goes through its cycle c Process while the ventricles are relaxing I ventricular diastole i Blood returns to resting heart through veins that empty into the right and left atria ii I pressure rises from the ow of blood into atria I AV valves open and blood ows into the ventricles iii Ventricles become about 80 filled during this time iv Relaxation d Contraction process I ventricular systole i Contraction of each ventricle increases the pressure within each chamber causing the AV valves to forcefully close 1 Prevents blood from backing up into the atria ii Pressure in ventricles force the semilunar valves open and blood ows into the arterial systems iii As ventricles relax I semilunar valves being to close prevents back ow 2 Describe the role of autorhythmic cells of the SA node a Specialized selfexciteable muscle cells b Initiates periodic action potentials without neural activation i Due to constant leakage of sodium ions into the cell that depolarizes the membrane c Sinoatrial node i Located in the wall of the right atrium B10 126 WEEK 3 ii Acts as pacemaker for the rest of the heart by producing spontaneous action potentials at a faster rate than other autorhythmic cells iii Generate an action potential every 06 seconds iv Depolarization initiated by this pacemaker transmitted through two pathways 1 One to the cardiac muscle fibers of the left atrium 2 One to the right atrium and the atrioventricular node AV a Wave of depolarization is conducted rapidly over both ventricles by a network of fibers called the atrioventricular bundleBUNDLE OF HIS i Fibers relay the depolarization to Purkinje fibers 1 Directly stimulate the myocardial cells of the left and right ventricles a Simultaneous contractions 3 Spreads quickly from one muscle fiber to another in a wave that envelops the right and left atria nearly simultaneously a Due to the gap junctions between the intercalated disks b Blocking spread of excitation through muscle fibers from one chamber to another is due to a sheet of connective tissue 4 Contractions are controlled by calcium ion and the troponintropomyosin system similar to skeletal muscles d EKG electrocardiogram i Shows how the cells of the heart depolarize and repolarize during the cardiac cycle 1 Depolarization causes contraction of the heart 2 Repolarization causes relaxation ii P wave 1 Produced by the depolarization of the atria 2 Associated with the atrial systole iii QRS peak 1 Produced by ventricular depolarization 2 Ventricles contract iv T peak 1 Produced by ventricular repolarization 2 Ventricles begin diastole e Arteries and veins branch from all parts of the body i Pulmonary arteries 1 Deliver deoxygenated blood from the right ventricle to the right and left lungs B10 126 WEEK 3 ii Pulmonary veins 1 Return oxygenated blood from the lungs to the left atrium of the heart iii Aorta 1 Branches are systemic arteries 2 Carries oxygenrich blood from the left ventricle to all parts 0 the body 3 Coronary arteries a First branches off the aorta b Supplies oxygenated blood to the heart muscle itself 4 Empties into two major veins a Superior vena cava i Drains upper body b Inferior vena cava i Drains lower body 5 Veins empty into right atrium 6 Flow of blood driven by pressure generated by ventricular contraction 3 Define blood pressure and how it is measured a b Contraction of ventricles cause the pressure blood pressure Pulse that is detectable in wrist and neck results from changes in pressure as elastic arteries expand and contract with the periodic blood ow Use blood pressure as a general indicator of cardiovascular health due to a variety of conditions can cause increases or decreases in pressure Sphygmomanometer i Measures the blood pressure in the brachial artery found on the inside part of the arm above the elbow Systolic pressure i Peak pressure at which ventricles contract Diastolic pressure i Ventricles are relaxed ii Pressure of the cuff is lower than the blood pressure throughout the cardiac cycle iii Blood vessel is no longer distorted and the pulsing sound stops Blood pressure is written as a ratio i Systolic pressure over diastolic pressure ii Healthy for age 20 I 12075 mmHg Hypertension i High blood pressure ii Systolic pressure greater than 150 mmHg iii Diastolic pressure 90 mmHg B10 126 WEEK 3 495 Characteristics of Blood Vessels 1 Describe the four tissue layers in blood vessels a Endothelium innermost i Epithelial sheet b Layer of elastic fibers i Allows recoil after each time they receive a volume of blood pumped by the heart 0 Smooth muscle layer 1 Connective tissue layer e Thick walls reduce exchange of materials between the blood and tissue outside the vessel 2 Explain the distinctions among arteries capillaries and veins a Arteries i Able to withstand pressure ii Narrower the vessel greater frictional resistance to ow iii Half the diameter of another 16 times the frictional resistance iv Resistance to blood ow increases by the fourth power v Vasoconstriction 1 Contraction of smooth muscle layer of the arterioles 2 Greatly increases resistance and decreases ow 3 Can lead to high blood pressure hypertension vi Vasodilation 1 Relaxation of the smooth muscle layer 2 Decreases resistance and increases blood ow to an organ vii Regulating body heat in endotherms and ectotherms l Vasodilation and vasoconstriction b Capillaries i Network for exchange ii Extensive branching ensure that every cell in the body is within 100 micrometers of a capillary iii Very narrow iv Greatest total crosssectional area v Blood travels much slower more time to exchange materials with the surrounding extracellular uid vi Blood released some oxygen and nutrients and picked up CO2 and other waste products vii Loses pressure and velocity as it moves through the arterioles and capillaries viii Velocity increases as crosssectional area decreases c Veins i Same layers of tissues as arteries thinner layer of smooth muscle ii Pressure in veins is only about one tenth that in the arteries iii Venous pump B10 126 WEEK 3 1 Skeletal muscle surrounding the veins can contract to move blood by squeezing veins iv Venous valves 1 Helps blood move in one direction through the veins back to the heart 3 Describe how the lymphatic system operates a Capillaries I arteriolar ends I returned to capillaries near venular ends i Returns by osmosis 1 Due to difference in protein concentration between plasma and interstitial uid b Edema i Increased interstitial uid causing swelling of the tissues ii Pregnant women swollen feet iii Plasma protein concentration is too low 1 Fluids do not return to the capillaries but remain in the interstitial uid c Open circulatory system I LYMPHATIC SYSTEM i Consists of 1 Lymphatic capillaries 2 Lymphatic vessels 3 Lymph nodes 4 Lymphatic organs a Spleen b Thymus ii Lymph 1 Excess uid in the tissues that drains into blindended lymph capillaries with highly permeable walls 2 Passes into progressively larger lymphatic vessels a Resembles veins and valves 3 Enter two major lymphatic vessels a Drain into left and right subclavian veins b Modified by phagocytic cells and lymphatic organs i Germinal centers 1 Activation and proliferation of lymphocytes location 4 Lymph hearts a Propel lymph movement in fish amphibians reptiles bird embryos adult birds 4 Diseases of the cardiovascular system a Atherosclerosis i Hardening of the arteries ii Large amounts of fatty materials and cholesterol 1 Impedes blood ow b Arteriosclerosis B10 126 WEEK 3 i Calcium is deposited in arterial walls ii Arteries have restricted blood ow iii Lack ability to expand as normal arteries do 1 Increase in blood pressure c Heart attack myocardial infarction i Insufficient blood supply to one or more parts of the heart muscle d Angina pectoris i Chest pain ii Warning sign that blood supply to the heart is inadequate e Stroke i Caused by interference With blood supply to the brain ii Blood vessel bursts in the brain Arteries I arterioles I capillariesl venules I veins BIO 126 WEEK 3 496 Regulation of Blood Flow and Blood Pressure 1 Describe how exertion affects cardiac output a Cardiac output definition i Volume of blood pumped by each ventricle per minute ii Calculated by multiplying heart rate by stroke volume volume of blood ejected by each ventricle per beat b Cardiac output increases during exertion ex running i Increase in both heart rate and stroke volume c Homeostasis of blood pressure i Depends on cardiac output and resistance to blood ow 1 BP Cardiac output X resistance a Increased BP i Produced by an increase in either heart rate or blood volume ii Increase of vasoconstriction b Decreased BP i Dehydration ii Baroreceptors 1 Detects change in blood pressure a Negative feedback loop as it responds to changes in blood pressure b Fall in BP i Number of impulses to the cardiac center is decreased ii Increased sympathetic stimulation and decreased parasympathetic stimulation of the heart and other targets iii Amplifies cardiac output c Rise in BP i Number of impulses of the cardiac center is increased ii Reduce cardiac output iii Lowers resistance 2 Located in arch of aorta and carotid arteries 2 Explain how hormones regulate blood volume a Antidiuretic hormone ADH vasopressin i Secreted in response to increase in osmolarity of blood plasma ii Stimulates the kidneys to retain more water in blood excreting less in urine b Aldosterone i Acts on kidneys to promote retention of Na and water in the blood c Atrial natriuretic hormone i Promotes sodium excretion B10 126 WEEK 3 ii Secreted in response to stretching caused by an increased blood volume d Nitric oxide i Paracrine regulators of blood vessels ii NO passes toward through the cell layers of the vessel 1 Causes smooth muscles that encase it to relax and blood vessels to dilate 2 Cause vasodilation that lessens resistance 1 BIO 126 WEEK 3 CHAPTER 48 THE RESPIRATORY SYSTEM POWERPOINT NOTES RESPIRATORY SYSTEM 0 Functions 0 Exchange of gases between the atmosphere blood 0 Homeostatic regulation of body pH 0 Protection from inhaled pathogens and irritating substances 0 Vocalization ADAPTATIONS FOR GAS EXCHANGE 0 All respiratory organs share certain common features 0 Moist surfaces in which gases dissolve and diffuse 0 Increased surface area for gas exchange 0 Extensive blood ow 0 Thin delicate structure GAS EXCHANGE VAIATIONS IN ANIMALS I Gases diffuse directly into unicellular organisms 0 However most multicellular animals require system adaptations to enhance gas exchange 0 Amphibians respire across their skin I Cutaneous respiration for gas exchange Echinoderms have protruding papulae Insects have an extensive tracheal system I Trachea air ducts that branch into very small tracheoles 0 In direct contact with individual cells I Spiracles openings in the exoskeleton can be opened or closed by valves 0 Fish use gills O Mammals have a large network of alveoli OO GILLS AND LUNGS I Gills O Specialized extensions of tissue that project into water 0 Increase surface area for diffusion 0 External gills are not enclosed within body structures I Found in immature fish and amphibians I Two main disadvantages I Must be constantly moved to ensure contact with oxygen rich fresh water 0 Are easily damaged B10 126 WEEK 3 O Gills of bony fishes are located between the oral buccal or mouth cavity and the opercular cavities 0 These two sets of cavities function as pumps that alternately expand 0 Move water into the mouth through the gills and out of the fish through the open operculum or gill cover I Gill lamellae 0 37 arches on each side of a fish s head 0 Each is composed of two rows of gill filaments 0 Each gill filament consist of lamellae I Thin membranous plates that project into water ow I Water ow past lamellae in 1 direction only I Gills and lungs O Lungs I Gills were replaced in terrestrial animals by lungs I The lung system involves moving air through branched tubular passage I Twoway ow system 0 Except birds I Amphibians 0 Formed as saclike outpouchings of the gut 0 Frogs have positive pressure breathing 0 Force air into their lungs by creating a positive pressure in the buccal cavity I Reptiles have negative pressure breathing 0 Expand rib cages by muscular contractions creating lower pressure inside the lungs I Mammals 0 Lungs of mammals are packed with millions of alveoli sites of gas exchange 0 Inhaled air passes through the larynx glottis and trachea 0 Bifurcates into the right and left bronchi which enter each lung and further subdivide into bronchioles 0 Alveoli are surrounded by an extensive capillary network I Lungs of birds channel air through very tiny air vessels called parabronchi I Unidirectional ow 0 Achieved through the action of anterior and posterior air sacs unique to birds I Expanded during inhalation they take in air I Compressed during exhalation they push air in and through lungs 0 Respiration in birds occur in two cycles BIO 126 WEEK 3 0 Cycle 1 I Inhaled air is drawn from the trachea into posterior air sacs and exhaled into the lungs 0 Cycle 2 I Air is drawn from the lungs into anterior air sacs and exhaled through the trachea 0 Blood ow runs 90 degrees to the air ow 0 Crosscurrent ow 0 Not as efficient as countercurrent ow LUNG STRUCTURE AND FUNCTION 0 Visceral pleural membrane covers the outside of each lung 0 Parietal pleural membrane covers the inner wall of the thoracic cavity 0 Pleural cavity space between two membranes 0 Normally very small and filled with uid 0 Causes 2 membranes to adhere O Lungs move with thoracic cavity 0 Inhalation 0 Thoracic volume increases through contraction of two muscle sets I Contraction of external intercostal muscles expands the rib cage I Contraction of diaphragm expands the volume of thorax and lungs O Produces negative pressure which draws air into the lungs CONTROL OF VENTILATION IN MAMMALS 0 Each breath is initiated by neurons in a respiratory control center in the medulla oblongata I Stimulate external intercostal muscles and diaphragm to contract causing inhalation I When neurons stop producing impulses respiratory muscles relax and exhalation occurs 0 Stretch receptors send signals to brain that lungs are in ated this inhibits stimulus to contract until exhalation I Muscles of breathing usually controlled automatically 0 Can be voluntarily overridden holding your breath GAS LEVELS IN THE BLOOD GAS PRINCIPLES MONITORING AND TRANSPORT GAS EXCHANGE PARTIAL PRESSURE 0 A pressure of 760 mm Hg is defined as one atmosphere of pressure 0 Partial pressure is the pressure contributed by a gas to the total atmospheric pressure 0 Atmospheric pressure is the sum of the partial pressure pressures exerted by each gas in air in proportion to their amounts B10 126 WEEK 3 0 P02 021 x 760 mmHg 160 mmHg 0 DIFFUSION IS DRIVEN BY PARTIAL PRESSURE GRADIENTS 0 Gas exchange is driven by differences in partial pressures 0 Blood returning from the systemic circulation depleted in oxygen has a partial oxygen pressure of about 40 mmHg 0 By contrast the P02 in the alveoli is about 105 mmHg 0 The blood leaving the lungs as a result of this gas exchange normally contains a PO2 of about 100 mm MONITORING BLOOD pH AND PCO2 0 Neurons are sensitive to blood PCO2 changes 0 Rise in PC02 causes increased production of carbonic acid H2CO3 lowering the blood pH 0 Stimulates chemosensitive neurons in the aortic and carotid bodies 0 Send impulses to respiratory control center to increase rate of breathing 0 Brain also contains central chemoreceptors that are sensitive to changes in the pH of the cerebrospinal uid GAS TRANSPORT HEMOGLOBIN 0 Consists of four polypeptide chains 0 Two alpha 0 Two beta 0 Each chain is associated with a heme group O Heme group has central iron atom that can bind a molecule of O2 0 Hemoglobin loads up with oxygen in the lungs forming oxyhemoglobin 0 Some molecules lose 02 as blood passes through capillariesl dexoyhemoglobin HEMOGLOBIN 0 Hemoglobin s affinity for O2 is affected by pH and temperature 0 pH effect is known as Bohr shift 0 Increased CO2 in blood increases H 0 Lower pH reduces hemoglobin affinity for O2 0 Results in a shift of oxyhemoglobin dissociation curve to the right facilitates oxygen unloading 0 Increasing temperature has a similar effect RESPIRATORY DISEASES 0 Lung cancer accounts for more deaths than any other form of cancer 0 Caused mainly by cigarette smoking 0 Follows or accompanies COPD 0 Lung cancer metastasizes spreads so rapidly that it has usually invaded other organs by the time it is diagnosed 0 Chance of recovery from metastasized lung cancer is poor with only 3 of patients surviving for 5 years after diagnosis B10 126 WEEK 3 BIO 126 WEEK 3 CHAPTER 48 THE RESPIRATORY SYSTEM LEARNING OBJECTIVE NOTES 481 Gas Exchange Across Respiratory Surfaces 1 Describe gas exchange across membranes a b C Diffusion of gases across the membrane gases must be dissolved Always aqueous since plasma membranes must be surrounded by water to be stable and to allow for gas exchange to occur concentration gradient Oxygen from air dissolves in a thin layer of uid that covers the respiratory surfaces Vertebrates i Gases diffuse into the aqueous layer covering the epithelial cells that line the respiratory organs Driven by the difference in O2 and C02 concentrations and their relative solubilities in the plasma membrane 2 Explain Fick s Law of Diffusion a b Rate of diffusion between two regions For a dissolved gas the rate of diffusion is directly proportional to the pressure difference between the two sides of the membrane and the area A over which the diffusion occurs R DAApd i R rate of diffusion ii A area over which diffusion occurs iii Delta p change in pressure iv d distance across which the diffusion must occur Optimization of R i Increase surface area ii Decrease distance iii Increase the concentration difference as indicated by Ap 3 Compare evolutionary strategies for maximizing gas diffusion a b C 05mm needs more than just diffusion i Limits size and structure of organisms that obtain oxygen entirely by diffusion from the environment Increasing oxygen concentration difference i Invertebrates 1 Lack specialized respiratory organs developed means of improving diffusion 2 Water current that continuously replaces the water over the respiratory surfaces I continuous water supply a External oxygen concentration does not decrease along the diffusion pathway b Oxygendepleted water is constantly replaced 0 Maximizes concentration difference Increasing area and decreasing distance B10 126 WEEK 3 i Mollusks arthropods echinoderms 1 Respiratory organs that increase the surface area available for diffusion a Gills trachea lungs b Increase the rate of diffusion by maximizing surface area A and decreasing distance d the diffusing gases must travel 2 Brings external environment close to internal uid B10 126 WEEK 3 482 Gills Cutaneous Respiration and Tracheal Systems 1 Describe how gills work a Gills definition i Specialized extensions of tissue that project into water ii Can be simple or complex 1 Simple a Papulae of echinoderms 2 Complex a Highly convoluted gills of fish b Gills give great increase in diffusion surface area that gills provide enables aquatic organisms to extract far more oxygen from water C External gills i Larvae of fish amphibians ii Disadvantages 1 Must be constantly moved to ensure contact with fresh water having high oxygen content 2 Inefficient respiration in smaller animals since it offers resistance to movement 3 Easily damaged since it is thin epithelium d Branchial chambers i Protect gills of some invertebrates ii Provide means of pumping water past stationary gills iii Movement of the limb draws water through the branchial chamberl creates currents over the gills e Operculum i Covers gills of bony fish ii Gills are located between the oral cavity buccal and oerpcular cavity 1 Cavities function as a pump that expands alternately to move water into the mouth through the gills and out of the fish through the open Operculum iii Fish that swim continuously immobile opercula 1 Swim with their mouths partly open a Forces water over the gills in what is known as ram ventilation f 37 gill arches on each side of a fish s head i Two rows of gill filaments 1 Contains thin membranous plates lamellae 2 Water ows in only one direction past the lamellae a Blood ow opposite to the direction of water movement 2 Explain the advantage of countercurrent ow 21 Definition B10 126 WEEK 3 i Water ows in one direction While blood ows in the opposite direction b Acts to maximize the oxygenation of the blood by maintaining a positive oxygen gradient along the entire pathway for diffusion i Increases Ap c Most efficient blood oxygenation process d Ensures that there is a gradient between blood and water throughout the length of the gill lamellae i Permits oxygen to continue to diffuse all along the lamellae so that the blood leaVing the gills has nearly as high an oxygen concentration as the water entering the gills e Fish gills are the most efficient of all respiratory organs 3 Cutaneous respiration a Requires constant moisture b Highly vascularized areas of thin epidermis c Cutaneous respiration definition i Process of exchanging oxygen and carbon dioxide across the skin d Mostly in amphibians 4 Tracheal systems a Arthropods b No single respiratory organ i Small branched cuticlelined air ducts I tracheae 1 Branched into small tracheoles a Series of tubes that transmit gases throughout the body b Direct contact With indiVidual cells c Oxygen diffuses directly across the plasma membranes c Air passes into trachea Via specialized openings I spiracles i Ability to prevent water loss by closing the spiracles B10 126 WEEK 3 483 Lungs 1 Explain why lungs work better than gills in air a Takes advantage of partial pressures of gases b Lung minimizes evaporation by moving air through a branched tubular passage c NitrogengtOxygengtArgongtC02 d Contain structural support that prevents their collapse 2 Compare the breathing mechanisms of amphibians and reptiles a Amphibians i Positive pressure breathing 1 Force air into lungs filling their oral cavity with air I close their mouth and nostrils and then elevate the oor of their oral cavity a Pushes air into lungs in the same way that a pressurized tank of air is used to fill balloons 2 Basically mouthtomouth for humans 3 Push air into lungs b Reptiles i Negative pressure breathing 1 Expands their rib cages by muscular contraction a Creates a lower pressure inside the lungs compared with the atmosphere I greater pressure pushes air into lungs 2 Like sucking water through a straw 3 Pull air into lungs 3 Describe the breathing cycle of birds a Channels air through tiny air vessels I parabronchi i Air ows in only one direction achieved by anterior and posterior air sacs b Only fresh air enters the parabronchi of the lung and the old air exits the lung by a different route c Respiration occurs in two cycles inhalation and exhalation phase i Air inhaled in one cycle is not exhaled until the second cycle ii Inhaled air enters posterior air sac both air sacs expand since anterior air sac takes air from lungs iii Air in posterior air sac is forced to enter lungs cycle is repeated d Crosscurrent blood ow through lungs Inhalation of air Mouth amp nose I pharynx I larynx I glottis I tracheal bronchi I bronchioles I lung I alveoli B10 126 WEEK 3 484 Structures Mechanisms and Control of Ventilation in Mammals 1 Explain how contraction and relaxation of the diaphragm and intercostal muscles result in breathing a Diaphragm structure 6 f i Convex sheet of striated muscle separating the thoracic cavity from the abdominal cavity Contraction i Lowering of the diaphragm and attening of the diaphragm I expansion of volume of thorax and lungs I bringing about negative pressure ventilation ii External intercostal muscles 1 Contraction of the external intercostal muscles between the ribs raises the ribs and expands the rib cage Elastic tension Relaxation i Production of unforced exhalation due to elastic tension is released 1 Allows thorax and lungs to recoil Each breath moves a tidal volume of about 500 mL in and out of the lungs 150 mL remains in the tubular passages where no gases are exchanged 2 Describe how the nervous system regulates breathing a b Initiated by neurons respiratory control center located in medulla oblongata Stimulate diaphragm and external intercostal muscles to contract I inhalation No impulses I relaxation of diaphragm and external intercostal muscles I exhalation Maintaining homeostasis I i Neurons must be responsive to blood P02 and PCO2 ii Rise in PC02 increased production of carbonic acidl lowers blood pH 1 Stimulates neurons in aortic and carotid bodies 3 List and characterize the major respiratory diseases a Hyperventilating though it is not a major disease or a disease at all i Breathing is excessive ii Blood PCO2 is abnormally lowered b Chronic obstructive pulmonary disease COPD C i Any disorder that obstructs air ow on a longterm basis ii Ex asthma chronic bronchitis emphysema iii Asthma l Allergen triggers the release of a histamine and other in ammatory chemical that cause intense constriction of the bronchi and sometimes suffocation Emphysema B10 126 WEEK 3 i Alveolar walls break down and lung exhibits large but fewer alveoli ii Lungs become less elastic iii Collapse and obstruct the out ow of air d Lung cancer i Follows or accompanies COPD ii Tumors originate in mucous membrane of large bronchi iii Coughing up of blood iv Metastasizes quickly usually invades other organs by the time it is diagnosed 4 Lung structure a Visceral pleural membrane i Thin membrane covering each lung b Parietal pleural membrane i Lines the inner wall of the thoracic cavity c Pleural cavity i Space between these two membrane sheets ii Small and filled with liquid 1 Causes the membranes to adhere a Couples the lungs to the thoracic cavity d If one lung fails the other one can still function due to the pleural membranes B10 126 WEEK 3 485 Transport of Gases in Body Fluids 1 Describe the structure of hemoglobin a Protein composed of four polypeptide chains b Contains four organic compounds called heme groups i Iron is in the middle of each heme group 1 Allows for binding wih oxygen c Can carry up to four molecules of oxygen 1 Oxyhemoglobin i Hemoglobin loaded up with oxygen in the alveolar capillaries of the pulmonary circulation ii As it passes through the systemic circulation oxygen is released I deoxyhemoglobin e Oxygencarrying molecule in all vertebrates f Oxygen carrier by many invertebrates annelids mollusks echinoderms atworms and even some protsists g Hemocyanin i Oxygen carrier in other invertebrates ii Free protein that is in hemolymph of arthropods h Provide and oxygen reserve i Blood cells is in the form of oxyhemoglobin j Myoglobin has a greater affinity for oxygen than hemoglobin 2 Predict hemoglobin s oxygen affinity in various environmental conditions a pH i Bohr Effect Bohr Shift 1 Result of H binding to hemoglobin ii Lower pH 1 More 02 is reeased b Temperature i Increasing temperature 1 Similar effect on hemoglobin s affinity for oxygen 2 More 02 is released 3 Explain how carbon dioxide is transported by the blood a 72 of the CO2 diffuses into the red blood cells b Dissolved in plasma c Bound to hemoglobin d Bicarbonate in plasma following a reaction with carbonic anhydrase in the red blood cells
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