Circulation and Respiration PDF

THE VASCULAR SYSTEM  Path of blood flow throughout the body Note: oxygenated and deoxygenated blood do not mix Pulmonary Circuit Systemic Circuit Pulmonary...

THE VASCULAR SYSTEM  Path of blood flow throughout the body Note: oxygenated and deoxygenated blood do not mix Pulmonary Circuit Systemic Circuit Pulmonary arteries Capillaries in head, neck, upper limbs Capillaries in lungs Systemic arteries Pulmonary veins Start The left atrium The right atrium collects blood from receives blood the pulmonary from the systemic circuit and empties circuit and passes it into the left it to the right ventricle, which ventricle, which pumps blood into pumps blood into the systemic circuit. the pulmonary circuit. Systemic veins 2 Capillaries in trunk and lower limbs From Visual Anatomy & Physiology, 1e Martini/Ober/Nath p.595  8 Capillaries of Superior vena cava head, chest, and arms Pulmonary Pulmonary artery artery Capillaries 9 Aorta Capillaries of right lung of left lung 2 7 2 3 3 4 5 10 4 Pulmonary Pulmonary vein 6 1 vein Right atrium 9 Left atrium Right ventricle Left ventricle Inferior Aorta vena cava Capillaries of abdominal region and legs 8 3 Chambers of the Heart Right Atrium: Receives deoxygenated blood from the superior and inferior Left Atrium: Receives venae cavae and from the oxygenated blood from cardiac veins through the the pulmonary circulation; coronary sinus; sends sends blood to left ventricle blood to right ventricle Key: Left Ventricle: Receives Oxygen-rich blood blood from the left atrium; Oxygen-poor blood sends blood to systemic circulation Right Ventricle: Receives blood from the right atrium; sends 4 blood to pulmonary circulation Myocardial Thickness and function Very thick wall of left ventricle generates high force necessary to send blood through all systemic arteries Wall of right ventricle is not as thick since the blood is sent through the pulmonary arteries 5  Ascending Pulmonary aorta trunk Heart Valves Superior vena cava Aortic arch The heart valves prevent the back flow of blood. Left pulmonary veins They open and close due to the pressure exerted by the blood Right atrioventricular (AV) valve (tricuspid valve) located b/w right atrium and right ventricle Left atrioventricular (AV) valve (bicuspid valve) Inferior located b/w left atrium vena cava and left ventricle Pulmonary valve Aortic valve From Visual Anatomy & Physiology, 1e 6 Martini/Ober/Nath p.634  Ascending Pulmonary aorta trunk Heart Valves Superior vena cava Aortic arch As the right atrium contracts, Left pulmonary veins the force of blood flow pushes the right AV valve open. As the left atrium contracts, Chordae tendineae the force of blood flow pushes prevent valves from the left AV valve open. opening back into the atria As the left ventricle Inferior contracts, the force of blood vena cava flow causes the AV valve to close, and pushes the aortic valve open. As the right ventricle contracts, the force of blood flow causes the AV valve to close, and pushes the pulmonary valve open. From Visual Anatomy & Physiology, 1e 7 Martini/Ober/Nath p.634  Heart sounds The sound of a heartbeat comes primarily from the turbulence in blood flow caused by the closure of the valves, NOT from the contraction of the heart muscle The first heart sound (lubb) – blood turbulence associated with the closing of the atrioventricular valves soon after ventricular systole (contraction) The second heart sound (dupp) – blood turbulence associated with the closing of the semilunar valves after ventricular diastole (relaxation) 8 8  The heart contracts and relaxes rhythmically the heart passively fills with blood (during diastole) and actively contracts and ejects the blood (during systole) Blood flows through the right side and the left side of the heart at the same time Oxygenated and deoxygenated blood never mix 9  The heart contracts and relaxes rhythmically during diastole: – the entire heart is relaxed, and blood flows from the veins into the atria – the atrioventricular (AV) valves are open 10  The heart contracts and relaxes rhythmically during systole: – atrial systole – contraction of the atria that completely fills the ventricles with blood – ventricular systole – ventricles contract and blood is sent out into large arteries (from left ventricle into aorta to systemic circulation; from right ventricle into pulmonary trunk to pulmonary circulation) 11  Coronary Arteries Just like every organ of your body, the cells of your heart require oxygen and nutrients to function properly Coronary arteries are the blood vessels that bring oxygen- and nutrient-rich blood to your heart cells Superior Aorta Vena cava Left Pulmonary coronary artery artery Right coronary artery Blockage Dead 12 muscle Figure 23.8A tissue  What is a heart attack? a heart attack occurs when a blockage prevents the delivery of oxygen and nutrients to your heart cells (the cells die) a stroke occurs when a blockage prevents the brain cells to get fresh blood Superior Aorta Vena cava Left Pulmonary coronary artery artery Right coronary artery Blockage Dead 13 muscle Figure 23.8A tissue  a heart attack or stroke most often results from the gradual obstruction of the arteries (disease called atherosclerosis) plaques form and restrict the blood flow. At some point, complete blockage can happen. Connective Smooth Plaque tissue muscle Epithelium LM 160  LM 60  14 Figure 23.8B Three major daily activities can influence the prevalence of cardiovascular diseases smoking can double the risk regular exercise can reduce the risk diet low in saturated fat, trans fat and cholesterol can help reduce the risk 15  Balloon Narrowed Some Solutions: Atherosclerotic lumen plaque of artery Coronary artery angioplasty Balloon catheter with uninflated balloon is threaded to obstructed area in artery When balloon is inflated, it stretches arterial wall and squashes atherosclerotic plaque After lumen is widened, balloon is deflated 16 and catheter is withdrawn Some Solutions: stent Stent Lumen of artery (c) Stent in an artery 17 (d) Angiogram showing a stent in the circumflex artery Some Solutions: coronary bypass Ascending aorta Grafted vessel 18 Obstruction (a) Coronary artery bypass grafting (CABG)  Treatments of cardiovascular diseases drugs To dissolve clots To lower cholesterol and/or blood pressure surgical Angioplasty – a balloon is inserted in the artery to compress plaques and widen clogged arteries Stents – a small wire mesh tube prop arteries open Bypass – blood vessels taken from the leg are sewn into the heart to shunt blood around clogged arteries 19 – Cardiac output – Amount of blood/minute pumped into systemic circuit – Heart rate – Number of beats/minute 20 Copyright © 2009 Pearson Education, Inc.  Conduction system of the heart 1. The SA Node (pacemaker) is a cluster of cells situated in the wall of the right atrium that generates electrical signals Pacemaker (SA node) Right atrium 1 Pacemaker generates signals to contract ECG 21  Conduction system of the heart 2. The electrical signals spread quickly through both atria, making them contract in unison and send the blood to the ventricles The signals also pass through a relay point called the AV node, in the wall between the right atrium and the right ventricle. This causes a delay (0.1 sec) ensuring that the atria contract and empty before the ventricles contract Pacemaker (SA node) AV node Right atrium 1 Pacemaker 2 Signals spread generates through atria signals and are delayed to contract at AV node 22 ECG  Conduction system of the heart 3. Specialized cardiac muscle fibers relay the signals to the walls of the ventricles down towards the apex of the heart (the region at the bottom of the heart) … Pacemaker (SA node) AV node Specialized muscle fibers Right atrium Apex 1 Pacemaker 2 Signals spread 3 Signals relayed generates through atria to apex of heart signals and are delayed to contract at AV node 23 ECG  Conduction system of the heart 4. … and up through the walls of the ventricles The signal triggers the strong contraction that drives the blood out of the heart Pacemaker (SA node) Specialized AV node muscle fibers Right atrium Apex 1 Pacemaker 2 Signals spread 3 Signals relayed 4 Signals spread generates through atria to apex of heart through signals and are delayed ventricle to contract at AV node ECG 24  Conduction system of the heart Pacemaker (SA node) Specialized AV node muscle fibers Right atrium Apex 1 Pacemaker 2 Signals spread 3 Signals relayed 4 Signals spread generates through atria to apex of heart through signals and are delayed ventricle to contract at AV node ECG 25 Abnormal rhythms may occur in a heart attack External defibrillator can restore rhythm Implanted artificial pacemakers can trigger normal rhythms Heart 26 Blood Vessels Veins: convey blood from the tissues back to Venules: convey the heart blood from the tissues into veins Arteries: carry Capillaries: site of exchange between blood from the the blood and body heart to the tissues tissues Arterioles: small arteries that connect to Capillaries: site of capillaries exchange between the blood and body tissues Note: large blood vessels have their own vessel supply (called 27 Vasa vasorum), because their wall is too thick for nutrients to 27 diffuse from the blood flowing through them.  Arteries and Veins Artery Vein (a) Artery LM x 60 28 From Visual Anatomy & Physiology, 1e Martini/Ober/Nath p.596 (b) Vein  epithelial cells form the endothelium smooth muscle in walls can reduce blood flow elastic fibers permit recoil after stretching Capillary Epithelium Basal lamina Valve Epithelium Epithelium Smooth Smooth muscle muscle Connective Connective tissue tissue Artery Vein Arteriole Venule 29  arteries carry blood Capillary to organs Epithelium Basal lamina Valve Epithelium Epithelium Smooth Smooth muscle muscle Connective Connective tissue tissue Artery Vein Arteriole Venule arteries and arterioles have thicker layers of connective tissue and smooth muscle (suitable for strength and elasticity against high pressure and rapid flow of blood) 30  veins carry blood Capillary to the heart Epithelium Basal lamina Valve Epithelium Epithelium Smooth Smooth muscle muscle Connective Connective tissue tissue Artery Vein Arteriole Venule blood flows at low velocity and pressure flaps of tissue act as one-way valves 31 Normal valve varicose veins occur when valves are malfunctioning. www.itiva.com blood accumulates in veins causing distension and inflammation (mostly in lower leg, eosophagus, and anal 32 32 canal (hemorrhoids). www.omahaveinspecialists.com  Capillaries thin walls – a single layer of epithelial cells narrow – red blood cells flow in a single file Red blood cell Capillary 33 Copyright © 2009 Pearson Education, Inc. Gas, nutrient and waste exchange takes place in capillaries Capillary Interstitial Diffusion of fluid molecules Tissue cell 34  Gas, nutrient and waste exchange takes place in capillaries When blood gets to the Relative sizes and capillaries, the velocity numbers of blood is at its lowest, vessels enhancing the Velocity (cm/sec) exchange of substances 50 40 between blood and 30 interstitial fluid 20 10 0 Arteries Arterioles Aorta Venules Veins Venae cavae Capillaries 35  Blood Pressure Blood pressure is the force blood exerts against the walls of the vessels Depends on cardiac output and the resistance of vessels cardiac output is: how much blood is being ejected from the left ventricle every minute resistance is: how hard is it for the blood to travel through the blood vessels 36  Blood Pressure Pressure in Pressure in arteries veins Blood pressure drives Pressure (mm Hg) 120 blood from the heart 100 Systolic pressure through arteries 80 60 Diastolic 40 pressure 20 As the blood flows from 0 the aorta to arteries to Relative sizes and numbers arterioles, a greater of blood vessels surface area is encountered, increasing Arteries Venules Veins Aorta Venae cavae Capillaries Arterioles the resistance to flow; this causes the pressure to drop 37  Blood Pressure Pressure in Pressure in arteries veins Pressure (mm Hg) 120 Systolic Once blood reaches the 100 80 pressure venules, the pressure 60 40 Diastolic is almost at zero; how 20 pressure 0 can the blood make its way back to the heart? Relative sizes and numbers of blood vessels Arteries Venules Veins Aorta Venae cavae Capillaries Arterioles 38  Direction of blood return blood flow in vein veins are squeezed between Valve muscles; contractions of (open) skeletal muscles (by walking Skeletal and moving) will move the muscle blood toward the heart large veins have one-way Valve valves that allow the blood to (closed) flow only toward the heart 39  Pressure in Pressure in arteries veins Pressure (mm Hg) 120 Systolic 100 pressure 80 60 Diastolic 40 pressure 20 Notice how velocity 0 does not necessarily Relative sizes and numbers correlate with pressure of blood vessels Velocity (cm/sec) 50 Velocity does not necessarily correlate 40 with pressure 30 20 10 0 Arteries Aorta Venules Veins Venae cavae Capillaries Arterioles 40  Blood distribution blood is not found in all capillaries of the body at one given time (dependent on the needs of a specific organ) blood flow and distribution is controlled by constriction and relaxation of smooth muscles of the arterioles i.e. vasoconstriction and vasodilation 41 Remember thermoregulation in the skin? 42  Blood distribution Precapillary sphincters blood is not found in all capillaries of the body at one given time (dependent on the needs of a specific organ) Capillaries Arteriole Venule in addition, blood flow and 1 Sphincters relaxed distribution is controlled by Thoroughfare channel constriction and relaxation of precapillary sphincters Arteriole Venule 43 2 Sphincters contracted Figure 23.11  Exchange of Solutes Between Blood and Interstitial Fluid The exchange of solutes between the blood and the interstitial fluid occurs by: diffusion through epithelial cells endo/exocytosis Water will move out of capillaries by leakage through the cleft between two epithelial cells of the capillary wall 44  Exchange of Solutes Between Blood and Interstitial Fluid Two kinds of pressure in the capillaries drive the flow of fluid: Blood pressure and osmotic pressure Tissue cells Osmotic Osmotic Arterial Venous pressure pressure end of end of capillary capillary Blood Blood pressure pressure Interstitial Net fluid Net fluid fluid movement out movement in 45 Figure 23.11B  Blood pressure (hydrostatic pressure): drives the fluid out of the capillaries at the arterial end Osmotic pressure: drives the fluid in the capillaries at the venous end – this is due to the high concentration of proteins in the blood Tissue cells Osmotic Osmotic Arterial Venous pressure pressure end of end of capillary capillary Blood Blood pressure pressure Interstitial Net fluid Net fluid fluid movement out movement in 46 Figure 23.11B  Structure and Function of Blood ~ 5 L of blood in a person Blood consists of cells floating around in plasma ions maintain osmotic balance, keep the pH stable (7.4), are necessary for cell functions (such as muscle and nerve cells) proteins maintain osmotic balance, act as buffers, or have specific functions in coagulation (clotting) or immunity (defense) plasma also contains substances in transition from one part of the body to another (O2, CO2, nutrients, wastes, hormones, heat) 47  Blood Cells Red Blood Cells carry oxygen to our tissues – will be discussed in the chapter White Blood Cells fight on the respiratory system infections – will be discussed in the chapter on the immune system Blood plasma Platelets are involved in hemostasis; a sequence of responses that stops LM 400x bleeding when blood Blood smear vessels are damaged (to prevent hemorrhages) 48  Structure and Function of Blood Blood consists of cells floating ~ 5 L of blood in around in plasma a person ~ 45% red blood cells (RBC) (erythrocytes) carry oxygen ~ 25 trillion red blood cells Cellular elements (45%) Cell type Number Functions ~ 250 million molecules of per µL (mm3) of blood Erythrocytes hemoglobin /RBC (red blood cells) 5–6 million Transport of oxygen (and Centrifuged carbon dioxide) blood ~ 1 billion molecules of O2 carried sample Leukocytes Defense and in one RBC (white blood cells)5,000–10,000 immunity White blood cells (WBC) defend the Basophil Lymphocyte body against infections and cancer Eosinophil Neutrophil Monocyte platelets are involved in blood clotting Platelets Figure 23.13 250,000– 49 Blood clotting 400,000  ABO Blood Groups BLOOD TYPE TYPE A TYPE B TYPE AB TYPE O A antigen B antigen Both A and B antigens Neither A nor B antigen Red blood cells 50  ABO Blood Groups BLOOD TYPE TYPE A TYPE B TYPE AB TYPE O Neither A antigen B antigen Both A and B antigens A nor B antigen Red blood cells Plasma Anti-B Anti-A Neither Both anti-A and antibody antibody antibody anti-B antibodies 51  RH blood groups People who are Rh+ have the D antigen on surface of their RBC Normal plasma contains no anti-Rh antibodies If Rh- person receives blood from Rh+ donor, anti- Rh antibodies will be formed – ok for the first transfusion, but danger upon 2nd exposure to the antigen Safe – Rh+ to Rh+ – Rh- to Rh+ 52 – Rh- to Rh-  CONNECTION Anemia Is an abnormally low amount of functional hemoglobin or red blood cells The hormone erythropoietin Is produced by the kidneys when tissues do not receive enough O2 – it regulates red blood cell production Some athletes Artificially increase their red blood Colorized SEM 3,400 cell production, a dangerous practice because the blood can get too thick 53 Figure 23.14  Hemostasis (NOT to be confused with homeostasis!) 1. Platelets first stick to exposed collagen fibers from wall of damaged vessel 54  Hemostasis 2. Platelets get activated and grow extensions to attach to one another – Platelets release substances to activate neighbouring platelets (what type of feedback mechanism is this?) 55 55 www.cafepress.com/+activated_platelets_sem_large_poster,664799442  Hemostasis 3. Activated platelets stick together to form a platelet plug, which temporarily stops the blood from leaking out 56 56 sciencephoto.com  Hemostasis NOTE: Plug is temporary, and needs to be reinforced by fibrin threads formed during the clotting process (next process) www.sanger.ac.uk 57  4. Clotting (coagulation) 1) Prothrombinase is formed in the blood, with the help of substances released either from the damaged tissue or from factors in the blood 3) Thrombin converts soluble fibrinogen into insoluble fibrin; fibrin traps red blood cells at the site of damage to 2) Prothrombinase form a clot converts prothrombin (inactive) into thrombin (active); Ca2+ necessary for this activation Plug reinforced by fibrin threads 58 formed during clotting process Platelets and clot formation 1 Platelets adhere to exposed 2 Platelet plug forms 3 Fibrin clot traps connective tissue blood cells Epithelium Connective tissue Platelet Platelet plug Figure 23.15A Colorized SEM 3,400 59 Figure 23.15B The Respiratory System 60 Functions of the respiratory system 1. Exchange of oxygen and carbon dioxide 2. Regulation pH 3. Smell 4. Filtration 5. Resonate Sound 6. Heat and Water exchange  What is Gas Exchange? Gas exchange is the interchange of O2 and CO2 between an organism and its environment – It is also called respiration Gas exchange is essential because energy metabolism requires O2 and produces CO2 Structure of the Respiratory System The respiratory system can be functionally divided into conducting airways and respiratory airways: Conducting Airways −Nasal passages −Mouth −Pharynx −Larynx −Trachea −Bronchi −Bronchioles * Conducting airways do not participate in gas exchange Structure of the Respiratory System The respiratory system can be functionally divided into conducting airways and respiratory airways: Respiratory Airways −Respiratory Bronchioles −Alveolar Structures * Respiratory airways do participate in gas exchange Airway Wall Structure Mucous blanket Simple epithelium Squamous Cilia epithelium Pseudostratified epithelium Smooth muscle Mucous gland ≤5µm Cartiliage  Lobule = smallest functional unit of the lung Consists of: −Branch of terminal bronchiole −Alveolar structures −Arteriole (carries blood into lung) −Pulmonary capillaries (wrap around alveoli) −Venule (carries blood away from lung)  each bronchiole ends in grape-like clusters of air sacs – each “grape” is Oxygen-rich called an alveolus blood Oxygen-poor blood Bronchiole each of our lungs contains millions of Alveolar alveoli Sac the inner surface of each alveolus is lined with a Blood capillaries squamous epithelium which forms the respiratory surface: this is where gas exchange takes place 67  Alveoli Type I alveolar cells − Alveolar structure Type II alveolar cells − Surfactant production Surfactant decreases surface tension and allows for greater ease of alveolar inflation  Alveolar expansion =  lung expansion  the part of an animal where gases are exchanged with the environment is called the respiratory surface respiratory surfaces are made up of living cells; their plasma membranes must be wet to function properly gases must be dissolved in water before they can diffuse across membranes 69 Air enters through the nasal cavity (or the oral cavity) Air then goes through the pharynx (throat) then the larynx (voice box) -- air can make the vocal cords vibrate The large tube that brings the air to the lungs is the trachea -- Rings of cartilage maintain the shape of the trachea and prevent it from collapsing -- epithelial cells secrete mucus to trap debris from air -- mucus swept up by cilia, which beat in sync 70 the trachea divides into two bronchi, one going to each lung each bronchus divides repeatedly into finer and finer tubes called bronchioles 71 Oxygen-rich blood Oxygen-poor blood Total surface area of Bronchiole alveoli is very large ~ 70 square meters, about ¼ the size of a tennis court Alveoli Notice how alveoli are surrounded by blood vessels – this is where Blood the gas exchange takes capillaries place O2 diffuses from the alveoli into the blood CO2 diffuses out of the blood into the alveoli 72 Respiration Requires Three Main Components Pulmonary Ventilation (movement of gases into and out of lungs) Perfusion (movement of blood through the lungs) Diffusion (of gases between lungs and blood and blood and tissue)  Pulmonary Ventilation (movement of gases into and out of lungs) How does air move into and out of the lungs? As the size of a closed Boyle’s Law (P=1/V) container decreases, the pressure inside the container increases Liquids and gases move from an area of high pressure to an area of low pressure  Pulmonary Ventilation (movement of gases into and out of lungs) During breathing, the pressure within the lungs changes, driving the movement of air in and out of the lungs For air to move inside the lungs, the pressure must be lower inside the lungs than outside − Must increase the size of the lungs For air to move out of the lungs, the pressure must be higher inside the lungs than outside − Must decrease the size of the lungs  Inhalation Volume Pressure Contraction of the diaphragm flattens the dome and increases the vertical dimension of the chest Contraction of the external intercostal muscles makes the ribs move upward  Exhalation Volume Pressure Quiet exhalation is a passive process Relaxation of the diaphragm and external intercostal muscles, as well as elastic recoil of chest wall and lungs, cause a reduction in the size of the intrathoracic cavity 78 Besides the difference in air pressure, three other factors influence pulmonary ventilation (how easy it is to breathe): 1. Surface tension of alveolar fluid Water molecules are attracted to each other and cause alveoli to collapse Surfactant is a mixture of phospholipids and lipoproteins that reduces surface tension − Note: Respiratory distress syndrome (RDS) in infants is due to a lack of surfactant 2. Compliance of the lungs (how easily the lungs expand) Compliance results from high elasticity and low surface tension − Scarring of lung tissue replaces elastic fibers with collagen fibers = decreased compliance 3. Airway resistance (diameter of airways) Contraction/relaxation of smooth muscles in airways − Note: Asthma is due to constriction and inflammation of airways Perfusion: Pulmonary Circulation  Hemoglobin Hemoglobin in red blood cells is responsible for transporting oxygen Hemoglobin is a protein with 4 subunits, each of which is attached to a heme group (non-protein), at the center of which is an iron atom Each iron atom can carry one O2 molecule – thus, every hemoglobin can carry up to 4 oxygen molecules Iron atom O2 loaded O2 in lungs O2 unloaded O2 in tissues Figure 22.10 Heme group 82 Polypeptide chain  Hemoglobin 98.5% of O2 is transported via hemoglobin O2 reversibly binds to hemoglobin O2 binding is effected by: − Partial pressure of O2 − pH − Temperature − CO2 concentration Note: CO2 is primarily transported as bicarbonate ions in the plasma  Diffusion: Factors affecting the exchange of O2 and CO2 The diffusion of gases across a membrane occurs independently for each gas − O2 diffuses down its own partial pressure gradient (independently of CO2) The rate of diffusion is influenced by several factors 1. Partial pressure difference 2. Surface area available for gas exchange 3. Diffusion distance 4. Solubility of the gases Diffusion: pH [O2] Factors affecting the Temp. [CO2] exchange of O2 and CO2 [O2] pH [CO2] Temp.  Breathing is automatically controlled Breathing control centers are located in the pons and medulla of the brain These automatic controls keep breathing in tune with body needs  Breathing is automatically controlled Breathing control centers control contracting of breathing muscles and set certain rate. – 10-14 breaths / min at rest CO2 and O2 sensors in the body sense CO2 and O2 levels in the blood breathing control centers in the brain (pons and medulla) respond to CO2 levels (decreases in pH) in the blood when CO2 levels are too high (pH is low), the brain sends signals to the diaphragm and the rib muscles to contract (i.e. you inhale) 87