BIOLOGY - CLUTCH CH.42 - CIRCULATORY SYSTEM.

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2 CONCEPT: GAS EXCHANGE AND CIRCULATION Respiratory system draws in gases from the environment, intakes O2 and outputs CO2 Circulatory system transports O2, CO2, nutrients, hormones, and blood cells Delivers O2 to cells for cellular respiration, and removes waste CO2 Ventilation movement of air, or water, through organs of gas exchange, like lungs or gills Gas exchange diffusion of O2 and CO2 at respiratory tissue surface Circulation transport of diffused gases throughout the body Cellular respiration O2 is final electron acceptor of ETC, and CO2 is byproduct of glycolysis and citric acid cycle Pulmonary circulation carries deoxygenated blood from the heart to the lungs, and oxygenated blood to the heart Deoxygenated blood carrying CO2 from tissues is moved from the heart to the lungs Waste CO2 diffuses into the lungs, where it is exhaled Inhaled O2 diffuses into the blood, and the oxygenated blood return to the heart Systemic circulation oxygen-rich blood moves through arteries to tissues throughout the body O2 diffuses into cells, to be used in the mitochondrial matrix Delivers nutrients and carries away waste from tissues Deoxygenated blood carrying CO2 returns to the heart from the tissues Page 2

3 CONCEPT: VASCULATURE Endothelium epithelial tissue that lines the interior surface of blood vessels and lymphatic vessels Arteries transport blood away from the heart, oxygenated in systemic loop, deoxygenated in pulmonary loop - Have elastic walls, and are wrapped in smooth muscle allowing them to change their diameter - Arterioles small arteries that branch off by capillary beds, have smooth muscle, and smaller diameter Veins transport blood to the heart, deoxygenated in systemic loop, oxygenated in pulmonary loop - Have less smooth muscle than arteries, but many veins run through skeletal muscles - Contain valves to prevent backflow of blood, since pressure is lower than in arteries - Veinules converge to form veins, formed from capillaries converging Capillaries tiny vessels with walls only one-cell thick with a diameter roughly equivalent to that of a red blood cell Only site of exchange between blood and tissues, endothelial tissue with no smooth muscle Capillary beds diffuse networks of capillaries running through tissues - Pre-capillary sphincters control blood flow to specific capillary beds Page 3

4 CONCEPT: HEART ANATOMY Heart muscular organ that contracts to generate pressure waves that push blood through blood vessels Atria receive blood from veins Ventricles receive blood from atria, and pump blood into arteries Atrioventricular valves prevent backflow from ventricle to atrium, tricuspid valve on right, mitral valve on left Semilunar valves prevent backflow from arteries to ventricles, pulmonary valve on right, aortic valve on left - Heart murmur blood moves back across a valve, often due to damage or infection in valve Pulmonary artery delivers deoxygenated blood from the heart to the capillary beds in the lungs Pulmonary veins delivers oxygenated blood from the lungs back to the heart Aorta delivers oxygenated blood from the heart to the tissues Venae cavae (superior and inferior) delivers deoxygenated blood to the heart from capillary beds in the bodies tissues Pulmonary circulation right atrium à right ventricle à pulmonary artery à lungs à pulmonary vein à left atrium Oxygenates the bloods in capillary beds at the alveoli of the lungs, gets rid of waste CO2 Systemic circulation left atrium à left ventricle à aorta à body tissues à venae cavae à right atrium Delivers O2 to tissues via capillary beds throughout the body, and picks up waste CO2 Page 4

5 CONCEPT: LUNG ANATOMY Pharynx throat area behind the mouth, shared passage way for air, food, and water Trachea brings air from pharynx to lungs, supported by c-shaped cartilage rings Larynx beginning of the trachea, contains the vocal folds Primary bronchi first branches into the lungs Bronchi branches from the primary bronchi that diffuse through the lungs, supported by cartilage Bronchioles smallest branches of the bronchi, supported by smooth muscle Lungs organs of respiration that inhale air to absorb O2, and exhale waste CO2 from cellular respiration Alveoli grape-like ends of the smallest bronchioles where gas exchange occurs between air and blood - Thin, aqueous interface between air and surrounding capillary bed - Surfactant mix of phospholipids and proteins produced by some alveoli to reduce surface tension Diaphragm sheet of muscle that separates thoracic (chest) and abdominal (belly) cavities Page 5

6 BIOLOGY - CLUTCH CONCEPT: BLOOD COMPOSITION Blood fluid that flows through blood vessels, transports nutrients and wastes, and performs gas exchange with tissues Plasma special extracellular matrix that composes the liquid part of blood Made of water, electrolytes, organic compounds, and dissolved gases Platelets small cell fragments that are involved in the blood clotting wound response Rapidly plug holes, while other factors are recruited to help seal the wound site Thrombus clot that forms in a blood vessel blocking blood flow White blood cells (leukocytes) immune system cells that help identify and fight infections Red blood cells (erythrocytes) carry O2 from the lungs via hemoglobin, lack nuclei and organelles at maturity Erythropoietin hormone secreted by the kidney to stimulate RBC production in bone marrow Respiratory pigments molecules that increase the oxygen-carrying capacity of blood, change color from O2 binding Hemoglobin protein made of 4 polypeptide subunits that contain hemes to bind oxygen - Heme iron-containing cofactor with porphyrin ring that is reduced/oxidized to transport O2 in RBCs Myoglobin primary pigment of skeletal muscles, contains only 1 heme, binds O2 tighter than hemoglobin Sickle-cell disease abnormal form of hemoglobin aggregates in RBCs, distorting shape, and inhibiting functions Page 6

7 CONCEPT: LYMPHATIC SYSTEM Lymphatic system network of lymphatic vessels that carry lymph toward the heart Drains plasma from interstitial fluid, and plays important role in the immune system Lymph clear fluid that circulates through lymphatic system, forms when interstitial fluid enters lymphatic ducts Lymph nodes organs of the lymphatic system that are critical to immune function Spleen and thymus important organs of lymphatic system Page 7

8 CONCEPT: HEART PHYSIOLOGY Heart circulates blood by filling it s chambers up from veins, then pushing the blood through arteries Atria thinner, less muscular walls than ventricles that receive blood from veins Ventricles thicker, more muscular walls that atria for powerful pumping into arteries Cardiac cycle complete cycle of pumping out blood, and filling up with blood Systole contraction phase of the cardiac cycle Diastole relaxation phase of the cardiac cycle Atria and ventricles in diastole blood flows into atria and ventricles Atria in systole, ventricles in diastole blood in atria pushed into through AV valves ventricles Atria in diastole, ventricles in systole blood in ventricles pushed into arteries through semilunar valves Page 8

9 BIOLOGY - CLUTCH CONCEPT: HEART PHYSIOLOGY Heart beats in response to electrical signals call action potentials Action potentials are generated by the movement of ions across the membrane Action potentials in the heart move between cells through gap junctions Intercalated discs special structure in heart muscle connecting neighboring cells, contains gap junction Sinoatrial node (SAN) group of cells in the right atrium that initiate heart contraction in vertebrates Pacemaker cells cells in SAN node that control rate and timing of heartbeat by starting action potentials Atrioventricular node (AVN) group of cells that pass the action potential from the atria to the ventricles Slightly delays the signal to give the atria time to empty completely into ventricles Purkinje fibers spread action potential through ventricles from the bottom to the top Electrocardiogram (EKG) records the electrical activity of the cardiac cycle Page 9

10 CONCEPT: HEART PHYSIOLOGY Diastole relaxation of ventricles and atria fills heart with blood SAN initiates atrial systole, causing the atria to contract AVN delays action potential, allowing atria to completely empty into ventricles Systole action potential starts at the bottom of the ventricles, and moves up through Purkinje fibers Ventricles contract and push blood through arteries Cardiac output volume of blood per minute that is pumped by the ventricles Heart rate heartbeats per minute Stroke volume volume of blood pumped by a single ventricle contraction Page 10

11 CONCEPT: HEART PHYSIOLOGY Systolic blood pressure highest blood pressure, measured at the peak blood pumping out of the ventricles Pulse rhythmic bulging of an artery with heartbeat allowing systolic blood pressure to be measured Diastolic blood pressure lower blood pressure measured right before ventricles contract and pump out blood Doctors give two numbers for blood pressure measurement: systolic bp/diastolic bp Hypertension long-term, abnormally high blood pressure Arteries have muscle fibers and elastic fibers to deal with the high pressure from ventricle contractions Aorta is especially dense with elastic fibers allowing it to withstand immense systolic pressure Blood slows as it moves through capillaries, experiencing a substantial drop in velocity and pressure Veins have the lowest blood pressure, have valves to prevent backflow Veins in extremities pass through skeletal muscles that contract to help push blood toward the heart Interstitial fluid fluid that leaks from capillaries and enters space outside of cells Hydrostatic pressure outward from capillaries to interstitial space due to pressure from heart Osmotic gradient inward from interstitial space to capillaries due to solute concentration in blood Arteriole end: hydrostatic pressure>osmotic pressure, venous end: hydrostatic pressure<osmotic pressure Page 11

12 BIOLOGY - CLUTCH CONCEPT: HEART PHYSIOLOGY Blood pressure must be regulated through a homeostatic system Baroreceptors pressure sensors found in the heart and arteries Cardiac output is increased in response to low blood pressure Vasoconstriction of specific arterioles diverts blood to important tissues Veins constrict to divert blood volume to heart and arteries Vasodilation of arteries leads to a drop in blood pressure Cardiovascular disease disorders that affect the heart or vasculature Arteriosclerosis hardening of arteries due to accumulation of fat deposits Cholesterol is transported in blood as low-density lipoprotein (LDL) and high-density lipoprotein (HDL) - LDL delivers cholesterol, and HDL scavenges excess cholesterol Myocardial infarction heart attack due to blockage of coronary arteries leading to damage of heart muscle tissue Stroke damage to nervous tissue in the brain from lack of O2, often due to blocked or ruptured artery Page 12

13 CONCEPT: RESPIRATORY PHYSIOLOGY Gas exchange allows animals to get O2 for cellular respiration, and get rid of waste CO2 from metabolism Small animals can perform gas exchange across their body surfaces due to high SA:V Respiratory organs provide surface area for gas exchange in larger organisms Positive pressure is like pushing, negative pressure is like pulling Positive pressure ventilation air is pushed into the lungs Negative pressure ventilation air is pulled into the lungs - Diaphragm pulls downward and ribs pull upward on thoracic cavity, creating negative pressure Page 13

14 CONCEPT: RESPIRATORY PHYSIOLOGY Dead space inhaled air that does not take part in gas exchange, trachea, bronchi, and bronchioles Tidal volume volume of air inhaled and exhaled with each breath Vital capacity volume of air at maximum inhalation and exhalation Residual volume air that remains after forced exhalation Partial pressure (PX) hypothetical pressure of a gas alone, but occupying the same volume at same temperature Partial pressure = total pressure x % composition of gas mixture At high altitude and sea level the % of each gas in atmosphere is the same, but the total pressure differs - Partial pressures of gases are lower at higher altitudes Gases diffuse based on partial pressures, move from higher partial pressure to lower partial pressure Page 14

15 CONCEPT: RESPIRATORY PHYSIOLOGY Fick s law of diffusion gases diffuse based on 5 criteria, most importantly surface area, distance, and partial pressure Increasing surface area for gas exchange increases rate of diffusion Decreasing the distance gases must travel, like the thickness of a membrane, increases rate of diffusion Increasing the difference in partial pressure between the two environments increases rate of diffusion Partial pressure drives O2 and CO2 diffusion in the lungs, blood, and tissues PO2 in the lungs is higher than PO2 in the blood, and PO2 in the blood is higher than PO2 in the tissues PCO2 in the lungs is lower than PCO2 in the blood, and PCO2 in the blood is lower than PCO2 in the tissues Muscles tend to have particularly low PO2, especially during exercise when energy demands increase In mammals each breath mixes fresh air mixes with oxygen-depleted air, so PO2 in alveoli is less that atmosphere Hemoglobin binds O2 to transport it in the blood, and unloads O2 at the tissues Cooperative binding in a binding system, the binding of one thing alters binding of subsequent things When hemoglobin binds one O2, it experiences a conformational change making it easier to bind another O2 High PO2 in lungs allows Hb to pick up lots of O2, low PO2 in tissues allows Hb to unload lots of O2 Page 15

16 CONCEPT: RESPIRATORY PHYSIOLOGY Oxygen dissociation curve, oxygen-hemoglobin equilibrium curve, or oxyhemoglobin saturation curve Sigmoidal curve that shows the O2 saturation of Hb at different PO2 Bohr shift shift to the right of the oxygen dissociation curve due to decreasing ph and increasing PCO2 Increasing PCO2 lowers Hb affinity for oxygen - Tissues that are consuming a lot of O2 will generate a lot of CO2, increasing PCO2 Lowering ph (increasing acid concentration) lowers Hb affinity for oxygen - CO2 combines with water to form carbonic acid in blood, lowering ph Decreased P CO2 Increased P CO2 Hb Affinity. Carbonic anhydrase enzyme that catalyzes the formation of carbonic acid (H2CO3) from CO2 and H2O Lowers PCO2 in blood, and lowers ph, inducing the Bohr shift and making Hb better at unloading O2 ph detectors in the respiratory center of the medulla oblongata help regulate ventilation Page 16