Circulatory System Chapter 12 PDF

CIRCULATORY SYSTEM - Ch. 12 FUNCTIONS: Transports gases between sites of external & internal respiration. Do you know another site with gas transport unrelated to respiration? physoclistous swim bladders CIRCULATORY SYSTEM - Ch. 12 FUNCTIONS:...

CIRCULATORY SYSTEM - Ch. 12 FUNCTIONS: Transports gases between sites of external & internal respiration. Do you know another site with gas transport unrelated to respiration? physoclistous swim bladders CIRCULATORY SYSTEM - Ch. 12 FUNCTIONS: Transports gases between sites of external & internal respiration. Also transports: products of digestion hormones waste products cells & chemicals of immune system heat CIRCULATORY SYSTEM - Ch. 12 TWO VASCULAR SYSTEMS: 1. Cardiovascular system- blood, vessels, heart. 2. Lymphatic system - lymphatic vessels & lymph. 2 1 CARDIOVASCULAR SYSTEM Blood Plasma - fluid component. Cells: Red blood cells - Erythrocytes carry hemoglobin, otherwise excreted. Leucocytes - white blood cells. immune response. Platelets - Thrombocytes important for clot formation. Plasma - 95% water, proteins, glucose, clotting agents, electrolytes….. CARDIOVASCULAR SYSTEM Do all vertebrates have red blood cells and hemoglobin? NO! 16 species of crocodile icefish occur in the Antarctic (Channichthyidae) Have neither red blood cells nor hemoglobin!!!! (but bigger heart) No myoglobin in skeletal muscles. O2 transported in plasma Can live in waters down to 28ºF with antifreeze proteins. Scale-less, no swim bladders. Low-density bone. Low metabolism. More blood, bigger vessels & heart. CARDIOVASCULAR SYSTEM Q: Does the blood passing through a shark heart differ from that passing through a dog’s (or pigeon’s) heart? CARDIOVASCULAR SYSTEM Artery vs Vein VESSELS What is difference between artery and vein? ARTERIES = take blood away from heart. VEINS = bring blood back to heart. directional terms Is it that, arteries always carry oxygenated blood? NO. Pulmonary arteries (mammals), blood to lungs, low O2. Ventral aorta (shark), blood to gills, low O2. CARDIOVASCULAR SYSTEM VESSELS HEART - ARTERY - ARTERIOLE - CAPILLARY - VENULE - VEIN - HEART Blood Pressure Varies with heart beat. Systolic (maximum) - when ventricle contracts. Diastolic (minimum) - low between contractions. 120/80 ave. Decreases away from heart. Friction - resistance to flow from walls of vessels. Increase in total cross-sect. area of vessels, big jump at capillaries.  CARDIOVASCULAR SYSTEM HEART - ARTERY - ARTERIOLE - CAPILLARY - VENULE - VEIN - HEART epithelium & elastin walls of various vessels smooth muscle & elastin connective tissue & collagen ARTERIES Highest blood pressures Walls with high elastin fiber content (T. intima & media). Absorbs sudden surge of energy (pulse), stretches. Elastic recoil moves blood along more smoothly. Arteriosclerosis (hardening of arteries) Lose elasticity due to deposits. Heart works harder (no recoil). Smaller vessels receive higher P and may rupture.  CARDIOVASCULAR SYSTEM MICROCIRCULATION HEART - ARTERY - ARTERIOLE - CAPILLARY - VENULE - VEIN - HEART epithelium & elastin walls of various smooth vessels &muscle elastin connective tissue & collagen MICROCIRCULATION Arterioles - capillary beds - venules. Arterioles & Venules - Smooth muscle + a little elastin. Capillaries = site of exchange. Thin walls with epithelium only & narrow lumen. Facilitates transport of gases, nutrients, waste, water, ions, heat…. CARDIOVASCULAR SYSTEM MICROCIRCULATION Controls arterial flow. Vasoconstriction/vasodilation Contraction or relaxation of smooth muscles narrows or expands lumen. Capillaries represent huge volume. Danger if all open…..shock/trauma - vasodilation, drop in B.P. Epinephrine (adrenaline) - vasoconstriction. Precapillary sphincters. Regulate flow to capillary beds. Adjust to activity levels. Under nervous + hormonal control. Capillary Beds. Overlap, redundancy. Tissues with multiple beds. With sphincters, adjust blood flow to activity level. CARDIOVASCULAR SYSTEM MICROCIRCULATION Blood to active tissues. Thanksgiving - ‘food coma’ Running w/o digesting - ischemia (‘side sticker’?). Heat transfer. Cooling - blood to skin, e.g. jack rabbit ears Ectotherm - adjusting to behavior (warming vs cooling). CARDIOVASCULAR SYSTEM MICROCIRCULATION HEART - ARTERY - ARTERIOLE - CAPILLARY - VENULE - VEIN - HEART epithelium & elastin smooth muscle & elastin connective tissue & collagen VEINS Large volume Thinner walls, smooth muscle, little elasticity, ‘baggy’. Reserve volume Up to 70% of blood may be in veins at one time. With activity, vasoconstriction, more blood in arterial vessels. CARDIOVASCULAR SYSTEM VEINS Blood flow product of: One-way valves prevent backflow. Skeletal muscle activity forces blood thru system. Activity moves more blood from reserve into arterial vessels. With long necks: Cardiovascular system must adjust with head movements to maintain consistent flow/pressure. Aortic pressure adjusts with head movements. Pooling prevented likely by vasoconstriction (raised) and vasodilation (lowered). Also affects kidneys. Arterial flow in legs very high. Lots of connective tissue surrounds leg vessels to prevent pooling.  CIRCULATION SYSTEMS Single Circulation Blood passes thru heart once during complete circuit. e.g. Shark, Perch (fish) Double Circulation Blood passes thru heart twice during complete circuit. e.g. Pigeon, you. (birds, mammals) Some intermediates…..lungfish, amphibians, reptiles at times. CARDIOVASCULAR SYSTEM Does blood passing through a shark heart differ from that passing through a dog? YES!! Dog - 2 streams, one low-O2 other high-O2. Shark - all low-O2 blood, one stream.  CIRCULATION SYSTEMS Single Circulation Blood passes thru heart once during complete circuit. e.g. Shark, Perch (fish) Double Circulation Blood passes thru heart twice during complete circuit. e.g. Pigeon, you. (birds, mammals) Some intermediates…..lungfish, amphibians, reptiles at times. RENOVATION Evolution works through modifying previously existing structures. Ample evidence in comparative vertebrate anatomy: Visceral arches Pharyngeal pouches Kidneys & urogenital system Aortic arches (arterial blood flow) “Evolution thru renovation.” “Archetype.” form = function + phylogeny CARDIOVASCULAR SYSTEM BLOOD VESSELS From mesoderm. Form early on, e.g. 48 hours in chick, quickly become large, complex. CARDIOVASCULAR SYSTEM ARTERIAL VESSELS Follow similar embryonic pathways in all vertebrates. Diverge through late stages of development. Basic pattern: Built upon gilled 1. Single ventral aorta from heart. vertebrate ancestor. 2. Six pairs of branchial arteries. 3. Paired dorsal aortae. e a Each arch with afferent & efferent branchial arteries. Basic pattern: all embryos, ~ shark, most fish. CARDIOVASCULAR SYSTEM Functions of basic pattern: afferent = to the gills Delivering low-O2 blood to gills. efferent = exits gills Each arch with afferent & efferent branchial arteries. Deliver blood to brain and head, internal & external carotids. Usually branch off anterior most arch (I). Internal carotids from efferent branchial or dorsal aortae. internal carotids (brain) external carotids (head) Basic pattern: all embryos, ~ shark, most fish. Example: Lamprey Pattern close to basic ideal. 8 pairs of arches. External carotids from efferent branchial III. Basic pattern: all embryos, ~ shark, most fish. Example: Shark Pattern close to basic ideal. Not a full set of arches. One happy shark!  ventral view: heart, aorta, afferent branchial = to the gills afferent branchial arches low O2 efferent branchial = leaves gills e for exit high O2 ventral view: dorsal aortae, efferent branchial arches lateral view CARDIOVASCULAR SYSTEM Lungfish: Need to switch from gills to lungs and back. Single vs double circulation!!!  CIRCULATION SYSTEMS Single Circulation Blood passes thru heart once during complete circuit. e.g. Shark, Perch (fish) Double Circulation Blood passes thru heart twice during complete circuit. e.g. Pigeon, you. (birds, mammals) Some intermediates…..lungfish, amphibians, reptiles at times. CARDIOVASCULAR SYSTEM Lungfish: Need to switch from gills to lungs and back. Single vs double circulation!!! Changes: Pulmonary arteries from VI. (Deliver blood to lungs). Divided atria and partial separation of ventricles in heart. Atria = chambers where blood enters heart. Arches III and IV connect directly to dorsal aortae - bypass gills. Why would bypassing gills be important? Lungfish: Largest vertebrate genome. 150 billion bp!!! Birds ave. 1.45 billion bp. “The fact that a large fraction of the lungfish genome may consist of repetitive DNA, transposable elements (TEs), and duplications further complicates whole genome analysis” Biscotti et al. 2016 Human only 3 billion bp. CARDIOVASCULAR SYSTEM Basal Tetrapods: (e.g., frog) Further modifications. Arches reduced to three principal ones, all paired. III - carotids to head and brain. IV - systemic arch for body. VI - with either pulmonary (lungs), pulmocutaneous (lungs + skin) or cutaneous (skin only). AMNIOTES More complicated, but modify III, IV, and VI. General loss of symmetry. Only III always paired. Ventral Aorta splits. Reptiles 3, Birds 2, Mammals 2. One to lungs and 1 or 2 as systemic. Arches III remain paired, carotids. IV - systemic arch Reptiles - paired. Birds - single from right side. Mammals from left side. (Rt = rt. subclavian artery). VI - unpaired, pulmonary trunk for lungs. Branches relate to rt. and lt.VI. AMNIOTES More complicated, but modify III, IV, and VI. General loss of symmetry. Only III always paired. Ventral Aorta splits. Reptiles 3, Birds 2, Mammals 2. One to lungs and 1 or 2 as systemic. Arches III remain paired, carotids. IV - systemic arch Reptiles - paired. BIRD Birds - single from right side. Mammals from left side. (Rt = rt. subclavian artery). VI - unpaired, pulmonary trunk for lungs. Branches relate to rt. and lt.VI. reptile Can trace contributions of various arches through embryology. Can also trace contributions of various arches through phylogeny of vertebrates. “Ontogeny recapitulates phylogeny.” CARDIOVASCULAR SYSTEM Venous System:Veins Very variable in arrangement (even within species). Functions: Drain body tissues (systemic, jugular). Drain lungs - pulmonary veins. - extension from lungs. Hepatic Portal System Renal Portal System CARDIOVASCULAR SYSTEM Venous System: Vitteline Veins Among first to form in embryo. Drain from yolk, along gut and into heart ❤. Bring nutrients from yolk. Bring O2-rich blood in amniotes. Gets incorporated into liver & hepatic portal system. CARDIOVASCULAR SYSTEM Venous System: Main Vessels Primitively: Paired anterior cardinal veins. Paired posterior cardinal veins. Paired common cardinal veins. “cava” = hollow, cave “vena” = vein CARDIOVASCULAR SYSTEM Venous System: Main Vessels Primitively: Paired anterior cardinal veins. Paired posterior cardinal veins. Paired common cardinal veins. In embryos, sharks, fish. Common cardinal vein “cava” = hollow, cave “vena” = vein CARDIOVASCULAR SYSTEM Venous System: Main Vessels Primitively: Paired anterior cardinal veins. Paired posterior cardinal veins. Paired common cardinal veins. More derived: Single precava (cranial vena cava) & postcava (caudal vena cava). From mosaic of embryonic vessels. pigeon has lt. & rt. anterior vena cava “cava” = hollow, cave “vena” = vein CARDIOVASCULAR SYSTEM Venous System: PORTAL SYSTEMS Vascular channel that begins in one set of capillaries and runs to another without passing through heart ❤. Hepatic Portal System: In all vertebrates. Connects digestive tract to liver. Transports absorbed nutrients to liver for storage & processing. Transports toxic stuff to be destroyed/detoxified. Transports the good and the bad. CARDIOVASCULAR SYSTEM Renal Portal System: In all vertebrates except mammals. Connects caudal blood (from tail) to kidney via renal portal vein. Subcardinal or renal vein drains kidneys. Blood then processed by kidney. therapsid from tail from tail from tail CARDIOVASCULAR SYSTEM Renal Portal System: In all vertebrates except mammals. Connects caudal blood (from tail) to kidney via renal portal vein. Subcardinal or renal vein drains kidneys. Blood then processed by kidney. from tail from tail from tail CARDIOVASCULAR SYSTEM Renal Portal System: In all vertebrates except mammals. Connects caudal blood (from tail) to kidney via renal portal vein. Subcardinal or renal vein drains kidneys. Blood then processed by kidney. Two factors likely favored this: 1. Primitively tail/axial muscles biggest and most active. 2. Low pressure of venous blood suitable for recovery of H2O and solutes. In contrast, mammals just have a renal artery and vein taking blood to and from kidney. therapsid from tail MAMMAL CARDIOVASCULAR SYSTEM HEART Hagfish unusual in having accessory ❤-like structures. Initially, simple tubular structure with four chambers in a row. Hagfish circulation Hagfish accessory hearts Simple 4-chambered heart CARDIOVASCULAR SYSTEM HEART BEAT Contraction intrinsic to cardiac muscle. Intercalated disks connect cells and ensure coordination of contraction. Cardiac muscle cell Intercalated disks CARDIOVASCULAR SYSTEM HEART BEAT Contraction intrinsic to cardiac muscle. Intercalated disks connect cells and ensure coordination of contraction. SA Node (sinoatrial node) near right atrium acts as pacemaker. Origin of contraction. Mammals also have AV Node (atrioventricular node) + Purkinje fibers, modified muscle cells that act neuron-like. CARDIOVASCULAR SYSTEM HEART BEAT Rate under nervous & hormonal control. Contraction Strength proportional to Volume of Returning Blood Starling Reflex: greater stretching of cardiac muscle = stronger contraction. More returning blood = more stretching = greater contraction. Works with reserve volume. Muscle activity sends more blood to ❤; so, stronger contraction. HEART OF A “FISH” Undivided = single circulation. 4 chambers in S-shaped arrangement: 1. Sinus venosus - thin walled receives hepatic and common cardinal veins. 2. Atrium - connected via sinoatrial valve. Also thin walled. 3. Ventricle - Thick walled, main driver of blood. 4. Conus arteriosus - contractile, cardiac muscle, conal valves. OR bulbus arteriosus - thin walled, smooth muscle. 2 1 2 4 4 1 3 3 perch dogfish HEART OF A “FISH” Operation: 1. Venous blood Muscular activity around veins drives blood toward heart. Aspiration effect: Pericardial cavity fairly rigid. After pumping blood, negative pressure in ❤ pulls blood into sinus venosus and atrium. 2. Sequential contractions moves blood from one chamber to next. 3. Valves (SA, AV, conal or bulbar) prevent backflow. 3 1 2 2 2 3 3 3 Lamprey through sharks, teleosts, heart pretty much the same. Note shift in 4 chambers of these hearts to those of crocs(!), birds, and mammals. HEART OF A LUNGFISH Shifts from single to double circulation! Several modifications: 1. Atrium partially divided. 2. Atrioventricular plug (not valve). 3. Ventricle partially divided. Skipping gills important. 4. Spiral valve in conus arteriosus. Prevents O2 loss to water. Divides blood flow when using lungs. Low-O2 blood (from body) to lungs. High-O2 blood (from lungs)to body, head & skips gills! High-O2 1 Low-O2 2 3 4 HEART OF AMPHIBIANS Somewhat similar to heart of lungfish. Note: Can use gills (larvae, some adults), lungs, skin or combo for respiration. Several modifications: 1. Atria fully divided. 2. Ventricle undivided but with trabeculae. 3. Spiral valve in conus arteriosus. #1-3 Structure & timing serves to separate blood flows. Muscular sphincter closes blood flow to lungs when diving. Shunts to skin for cutaneous respiration. 1 schematic 3 2 bullfrog heart HEARTS - end members primitive four chambers in pairs fully divided flow bird & crocs and mammals pumps low O2 blood to lungs, high O2 blood to body in between lungfish amphibians some reptiles four chambers in line undivided flow fish, chondrichthyans pumps low O2 blood to gills CARDIOVASCULAR SYSTEM HEART Q: Is a broken heart for real? HEART OF REPTILES Complex ❤ and plumbing (3 aortae). Accommodates apnea, periods of non-breathing. Occurs when submerged, hibernating/aestivating, quiet time. box turtle hibernating HEART OF REPTILES Turtle, Lizard and Snake ❤’s: Single ventricle but partially divided with shunt. Muscular ridge separates cavum venosum (r) from cavum pulmonale (l). Cavum arteriosum (interventricular canal) to cavum venosum. Fills with high-O2 blood from left atrium when breathing. Results: 1. Separation of O2-poor from O2-rich blood. 2. Accommodates apnea Can tune volume of blood to lung independent from that to body/head. HEART OF REPTILES Crocodile ❤: 4 chambered Ventricles fully divided. So, like that of birds and mammals. But has apnea. Foramen of Panizza Connects left and right systemic arches. Shunts high-O2 blood when breathing to body. Limited use during apnea. Bartolomeo Panizza 1 BREATHING APNEA HEARTS OF BIRDS & MAMMALS More straight forward: 2 atria, 2 ventricles. 4 chambers but distinct from four of fish ❤. No sinus venosus. Reduced to SA-node in mammals (where contraction begins). Conus arteriosus splits to form pulmonary trunk (w/ VI) and aorta (w/ IV). Good for endothermy & double circulation with complete separation of high-O2 and low-O2 blood. But cannot vary. Blood to lungs (volume) always = Blood to body (volume). HEART TRIVIA The entirety of your blood passes through your heart in one minute. Your heart could empty a swimming pool in a week. Heart was the last organ to be operated on…largely do the challenges of working on a very active organ. HEART TRIVIA takoyaki Q: Is a broken heart for real? You can have a “broken heart,” not necessarily fatal: Takotsubo Cardiomyopathy (broken heart syndrome) Heart changes shape after emotional stress. Shortness of breath, chest pain, palpitations, nausea. HEARTS OF BIRDS & MAMMALS More straight forward: 2 atria, 2 ventricles. But cannot vary. Blood to lungs (volume) always = Blood to body (volume). Apnea in diving birds and mammals Decrease ❤-rate (bradycardia). Anaerobic metabolism in muscles increases. Microcirculation alters blood flow to needed organs/tissues. double circulation mixed circulation single circulation HEARTS - end members primitive four chambers in pairs fully divided flow bird & crocs and mammals pumps low O2 blood to lungs, high O2 blood to body in between lungfish amphibians some reptiles four chambers in line undivided flow fish, chondrichthyans pumps low O2 blood to gills  double circulation “leaves lungs (to) left” - blood returning from lungs goes to left atrium, then left ventricle. Blood returns to rt atrium, then rt ventricle, then to lungs. lungs - lt atrium - lt ventricle - body/head - rt atrium - rt ventricle - lungs Major shift in circulation at birth for placental mammals Transition involves a few key features of embryo-neonate: EMBRYO 1. Umbilical vein - from placenta, high O2 + nutrients. 2. Ductus venosus 3. Foramen ovale 4. Ductus arteriosus 5. Umbilical arteries - to placenta, low O2. Major shift in circulation at birth for placental mammals Transition involves a few key features of embryo-neonate: Blood from placenta 1. Umbilical vein (high O2 + nutrients). 4 2. Bypasses liver (mostly) via ductus venosus. 3 3. Enters rt atrium and most skips ventricle, goes via foramen ovale to left atrium. 4. Some to rt atrium to rt ventricle to 2 pulmonary trunk, but bypasses lungs via ductus arteriosus. Mixes w/ aortic blood to body. 1 5. Blood returns to placenta via 5 umbilical arteries. Major shift in circulation at birth for placental mammals Transition involves a few key features of embryo-neonate: Numbers correspond to earlier slide. w/ first breath = lungs open 4 Umbilical blood flow cut off. 3 Blood flows to lungs, ductus arteriosus closes (ligamentum arteriosum). Blood returning from lungs closes foramen ovale (fossa ovalis). 1 5 Major shift in circulation at birth for placental mammals Transition involves a few key features of embryo-neonate: 4 4 3 3 2 1 1 5 5 Major shift in circulation at birth for placental mammals Transition involves a few key features of embryo-neonate: EMBRYO NEONATE 1. Umbilical vein 1. Round ligament of liver (on falciform). - from placenta, high O2 + nutrients. 2. Ductus venosus 2. 3. Foramen ovale 3. Fossa ovalis 4. Ductus arteriosus 4. Ligamentum arteriosum 5. Umbilical arteries 5. Round ligament of urinary bladder. - to placenta, low O2. Homologous remnants of embryonic features. Major shift in circulation at birth for placental mammals Transition involves a few key features of embryo-neonate: 4 4 3 3 2 1 1 5 5 Patent Foramen Ovale (PFO) In 25-33% of adults foramen ovale never closes. patent = “unobstructed Pressure largely keeps closed, but some leakage. Increased risk of stroke, migraines, decompression illness, high altitude pulmonary edema. (Once considered to have no health risk.) HEAT TRANSFER Microcirculation moves blood to or away from skin. With exercise or high environmental temps, blood shunted to skin for cooling. HEAT TRANSFER - RETES Adjacent networks of arteries and veins. Act as heat block with countercurrent flow. Important in aquatic vertebrates. e.g. duck feet, dolphin fin. With activity, artery expands and pinches off venous flow. Venous flow takes alternate, more surficial route (hence cooling). HEAT TRANSFER - RETES Adjacent networks of arteries and veins. Act as heat block with countercurrent flow. Important in aquatic vertebrates. e.g. duck feet, dolphin fin. Sperm production - pampiniform plexus. = countercurrent heat exchange. pampiniform plexus HEAT TRANSFER - RETES Carotid rete Keeps brain from overheating. Blood returning from nose/turbinates passes by carotids and cools. Rabbits without. LYMPHATIC SYSTEM 2nd part of Circulatory System (Cardiovascular + Lymphatic). Has its own vessels, tissues + fluid. Lymphatic vessels, lymphatic tissue, lymph. 3 functions: 1. Recapture ‘lost’ fluid of cardiovascular system (interstitial or tissue fluid). 2. Absorb fats. 3. Removal + destruction of harmful invaders. Lymph Mostly water plus some electrolytes & proteins.. Capillaries leaky by design, lose fluid. Hydrostatic pressure drives fluid out. Osmotic pressure helps recapture. Venous system captures 90%. 10% remains in tissues. Lymphatic Vessels Walls like veins, little muscle but 1-way valves. Rely on body movements (breathing, muscle contraction, arteries). Some verts (teleosts, some amph./repti) with lymph ❤’s., smooth muscle pumps. Drain back into veins (e.g. subclavian vein).  Lymphatic Vessels Lacteals = special vessels around digestive tract that absorb lipids (fats). Lymphatic Tissue Free cells - Leukocytes: Lymphocytes - produce antibodies. Macrophages - attack foreign bodies. Lymph Nodes. In mammals and some birds. Bound by connective tissue. Located along lymph vessels, fluid percolates through. Place to attack foreign bodies. Lymphatic Tissue Lymph Nodes. May swell with infection, e.g. bubonic plague (‘bubos’ = swelling). Cancer treatment may involve examination. Cancer may accumulate and warrant removal. Concern if moved beyond. lymphoma = cancer that starts in lymph nodes CIRCULATORY SYSTEM - Ch. 12 TWO VASCULAR SYSTEMS: 1. Cardiovascular system- blood, vessels, heart. 2. Lymphatic system - lymphatic vessels & lymph. 1 2