BL1004 Circulation Oct 2024 PDF

BL1004-Circulation Prof. Sarah Culloty, School of BEES [email protected] Heme group Iron atom O2 loaded O2 in lungs O2 unloaded In tissues O2 Polypep...

BL1004-Circulation Prof. Sarah Culloty, School of BEES [email protected] Heme group Iron atom O2 loaded O2 in lungs O2 unloaded In tissues O2 Polypeptide chain The circulatory system  Allows exchange with the environment  Provides an internal transport system for oxygen, carbon dioxide, nutrients and waste products. Why do we need circulation?  Diffusion is inefficient > few millimetres so unless you are small and/or passive you need a mechanism for gas exchange and nutrient/chemical transport. Circulatory systems  Three basic components:  A transport system – the circulatory fluid (blood)  A set of tubes (blood vessels)  A muscular pump (the heart)  Open circulatory systems – blood may be only partially or not at all confined to blood vessels e.g. insects and most molluscs, arthropods  Closed circulatory systems – blood completely confined to blood vessels e.g. earthworms, squid, octopus and all vertebrates Insects – Open circulatory system  As heart relaxes it Heart draws haemolymph into circulatory system Hemolymph in sinuses through valved surrounding organs pores called ostia Anterior Ostia Lateral vessel vessels Tubular heart (a) An open circulatory system Earthworms – closed circulatory system  Closed systems Heart are more efficient in larger, more active animals  e.g. squid, Interstitial fluid Small branch vessels in each organ octopuses and all vertebrates Dorsal vessel (main heart) Auxiliary hearts Ventral vessels (b) A closed circulatory system Questions!  What is an open circulatory system?  What is a closed circulatory system?  What are the functions of ostia in insects Vertebrate cardiovascular system Blood Vessels: Arteries – from heart to arterioles to capillaries Veins – from venules to capillaries to heart Capillaries (where exchange of gases and nutrients occurs) 2 to 4 Chambered Heart: ▪ Atria (singular, atrium)/auricles and Ventricles Fish: Single circulation A fish heart has two main chambers:  one ventricle and  one Blood pressure atrium drops as it flows through the 2 capillary beds. This limits the aerobic metabolic rate of fishes Double Circulation NB Blood passes through the heart twice per circuit The mammalian cardiovascular system 7 Capillaries of Anterior head and vena cava forelimbs Aorta Pulmonary Pulmonary 9 artery artery 6 Capillaries of right lung Capillaries 2 of left lung 3 4 3 11 Pulmonary vein Pulmonary 5 Left atrium vein 1 Right atrium 10 Left ventricle Right ventricle Aorta Posterior vena cava Capillaries of abdominal organs 8 and hind limbs Cardiac Cycle  Systole [sis-tuh-lee] = contraction phase  Diastole [dahy-as-tl-ee] = relaxation phase  The cardiac output depends on:  heart rate = pulse (beats per minute)  stroke volume (amount pumped by left ventricle per contraction = 75ml)  The beat is maintained by sinoatrial (pacemaker) and atrioventricular nodes  Blood vessels Arteries have thicker, Artery Vein Slow blood flow more elastic walls than in capillaries allows veins to help exchange of gases maintain blood Basement membrane and nutrients pressure between Endothelium 100 µm heart contractions Endothelium Endothelium Valve Smooth Smooth muscle muscle 15% of blood fluid CapillaryConnective Connective and proteins leak tissue tissue Muscle movement into Lymphatic Artery Vein squeezes blood System and are through veins returned near right atrium Venule Arteriole  Medical conditions  Atherosclerosis  caused by the buildup of low-density lipoproteins (“bad cholesterol”) within arteries  Hypertension or high blood pressure  promotes atherosclerosis and increases the risk of heart attack and stroke  Heart attack  the death of cardiac muscle tissue resulting from blockage of one or more coronary arteries, often caused by blood clot (ruptured plaque = embolus)  Stroke  the death of nervous tissue in the brain usually resulting from rupture or blockage of arteries in the head Blood  Blood is a connective tissue consisting of: Cells (45% by volume) Plasma (90% water + solutes) Blood (mammals) Cellular elements 45% Cell type Number Functions per L (mm3) of blood Erythrocytes (red blood cells) 5–6 million Transport oxygen and help transport carbon dioxide Separated blood elements Leukocytes 5,000–10,000 Defense and (white blood cells) immunity Basophil Lymphocyte Eosinophil Neutrophil Monocyte Platelets 250,000 Blood clotting 400,000 Haemoglobin in the red blood cells Heme group Iron atom O2 loaded O2 in lungs O2 unloaded In tissues O2 Polypeptide chain Review Qs from Respiration  Gas exchange occurs in the X in humans  The transport protein in human blood for O2 is?  The tidal volume of the human lungs is?  The residual volume is?  Openings on the surface of the insect body to facilitate respiration are called X Revision questions  What is single circulation?  What is double circulation?  What are the three main components of the cardiovascular system in humans?  Largest blood vessel in humans?  Acknowledgements  Majority of text and Powerpoint slides from Campbell’s Biology.