The Circulatory System PDF

The Circulatory System  Circulatory System § Any system of moving fluids that reduces the functional diffusion distance that nutrients, wastes and gases must traverse. § The transport system in most invertebrates is primarily through diffusion and bulk flow. TRANSPORT SYSTEM...

The Circulatory System  Circulatory System § Any system of moving fluids that reduces the functional diffusion distance that nutrients, wastes and gases must traverse. § The transport system in most invertebrates is primarily through diffusion and bulk flow. TRANSPORT SYSTEM IN INVERTEBRATES  Poriferans (Sponges) § Circulate water from the external environment through their bodies, instead of circulating an internal fluid § They use their pores (many incurrent pores, and one excurrent pore, which is called osculum) for the circulation of water from the environment  Cnidarians § Have a fluid-filled internal gastrovascular cavity. § This supplies nutrients for all the body cells lining the cavity, provides oxygen from the water in the cavity, and is a reservoir for CO2 & other wastes. § A simple body movement moves the fluid.  Platyhelminthes (flatworms) § The gastrovascular cavity of flatworms is more complex than Cnidarians in that it is branched and runs close to all body cells, diffusion distances for nutrients, gases, and wastes are short. § One disadvantage of branched gastrovascular cavity is that it limits these animals to relatively small sizes or to shapes that maintain small diffusion distances  Nematodes (Roundworms) § Use the coelomic fluid of their body cavity for transport. § Most of these animals are small, and movements of the body against the coelomic fluids, which are in direct contact with the internal tissues and organs, produce adequate transport.  Cardiovascular (Circulatory) System § (Gr. kardia, heart +L.vascular, vessel) § a specialized system in which a muscular, pumping heart moves the fluid medium called blood (or hemolymph) in a specific direction determined by the presence of unidirectional blood vessels. § The animal kingdom has 2 basic types of circulatory system: § Open Circulatory system § the heart pumps hemolymph out into the body cavity or at least through the parts of the cavity, where the hemolymph bathes the cells, tissues, and organs. § Characteristic of: Molluscs, Arthropods and Echinodermata § Closed Circulatory system § blood circulates in the confines of tubular vessels. § Characteristic of: Cephalopods (like octopus), Annelids and Chordates (vertebrates) Open and Closed Cardiovascular System Open Cardiovascular System (Mollusc) TRANSPORT SYSTEM IN VERTEBRATES  Transport System in Invertebrates § All vertebrates have closed circulatory system in which the walls of the heart and blood vessels are continuously contracted, and blood never leaves the blood vessels.  Characteristics of Vertebrate Blood and Blood Cells § Overall, vertebrate blood § transports oxygen, carbon dioxide, and nutrients § defends against harmful microorganisms, cells, and viruses § prevents blood loss through coagulation (clotting) § helps regulate body temperature and blood pH § Like other connective tissues, blood contains: § Plasma- fluid matrix § Formed elements- cellular elements  Plasma § (Gr. anything formed or molded)- 55% of the blood § is the straw-colored, liquid part of the blood § In mammals, made up of: § Water- 91% of plasma and provides the solvent for dissolving and transporting nutrients. § Plasma proteins- comprises 7% of the plasma § Albumin- about 60% of the total plasma proteins; plays important roles with respect to water movement § Fibrinogen- for blood coagulation (clotting) § Globulins- include the immunoglobulins (used as antibodies) and various metal- binding proteins. § Serum is plasma from w/c the proteins involved in blood clotting have been removed. The gamma globulin portion functions in the immune response because it consists mostly of antibodies.  Formed elements § 45% of the blood § Includes: § Erythrocytes (RBC) § Leukocytes (WBC) § Thrombocytes (Platelets)  Red Blood Cells (RBC) § Also known as Erythrocytes § Gr. erythros, red+ cytes, cells) § Vary dramatically in size, shape and number in the different vertebrates. § salamander Amphiuma- has the largest RBC among all vertebrates § ostrich- largest RBC among birds § RBCs can be: § nucleated (with nucleus)- in most vertebrates (most fishes, some amphibians, reptiles and birds) § enucleated (without a nucleus)- in mammals, some fishes and amphibians  Red Blood Cells (RBC) § Most mammalian RBCs are biconcave disk, which provides a large surface area for gas diffusion. § However, the camel and llama have elliptical RBC. § Generally, the lower vertebrates tend to have fewer but larger RBCs than the higher vertebrates § Almost the entire mass of a RBC consists of hemoglobin, an iron-containing protein. § Major function of erythrocyte: to pick up oxygen from the environment, bind it to hemoglobin to form oxyhemoglobin, and transport it to body tissues. § Hemoglobin also carries waste carbon dioxide (in the form of carbaminohemoglobin) from the tissues to the lungs (or gills) for removal from the body. § Life span of RBC in humans: 120 days  White Blood Cells (WBC) § Also known as Leukocytes § (Gr.leukos, white + cytes, cells) § less numerous and larger than RBC § are scavengers that destroy microorganisms at infection sites, remove foreign chemicals, and remove debris that results from dead or injured cells. § All WBC’s are derived from immature cells in bone marrow by a process called hematopoiesis. § Life span of WBC in humans: most live in few days except lymphocyte can live for several months or years § Types of WBC: § Granulocytes: Neutrophil, Eosinophil, and Basophil § Agranulocytes: Lymphocytes and Monocytes  Granulocytes § has granules in the cytoplasm; include § Neutrophil § 60-70% of the WBC § the most numerous of white blood cells § chemically attracted to sites of inflammation § responds quickly to bacterial infection § are active phagocytes § Eosinophil § 2-4% of WBC § are phagocytic and ingest foreign proteins and immune complexes § increased during parasitic and allergic reaction § Basophil § 0.5-1%; the least numerous WBC. § when they react with a foreign substance, their granules release histamine and heparin. Histamine caused blood vessels to dilate and leak fluid at the site of inflammation, and heparin prevents blood clotting  Agranulocytes § without granukes in the cytoplasm § Monocytes § 3-8% of the WBC § largest of formed elements § capable of phagocytosis as it transforms to macrophages § Lymphocytes § 20-25% of WBC § second most abundant WBC § Two distinct types of lymphocytes: (both of which is central to immune response) § B-cells § originate in the bone narrow and colonize the lymphoid tissue, where they mature; when B cells are activated, they divide and differentiate to produce plasma cells which produce antibodies. § T-cells § associated with and influenced by the thymus gland and play their role in the immune response  Thrombocytes (Platelets) § are disk shape cell fragment that initiate blood clotting § no nucleus but many vesicles § When a blood vessel is injured, platelets immediately move to the size and clump, attaching themselves to the damages area, and thereby beginning to the process of blood coagulation. § Life span in humans: 7-8 days  Vertebrate Blood Vessels § Arteries § are elastic blood vessels that carry blood AWAY FROM THE HEART to the organs and tissues in the body. § Veins § are relatively inelastic, large vessels that carry blood from the body tissues TOWARDS THE HEART. § Capillaries § composed of single layer of endothelial cells and the most numerous blood vessels in an animal’s body; formation of branched arterioles. § The central canal of all blood vessels is called lumen. The lumen of arteries and veins are composed of three layers.  Comparison between Arteries and Veins Features Arteries Veins Size of lumen Relatively smaller Larger Thickness of wall Thicker Thinner Carry blood Carry blood AWAY Flow of blood TOWARDS the from the heart heart Carries Carries oxygenated unoxygenated Kind of blood blood arising from blood towards the transported heart except the heart except pulmonary artery pulmonary vein Manner of blood Blood flows in spurts Blood oozes when cut Present; permits Presence of valves None blood flow only in one direction THE HEART AND CIRCULATORY SYSTEMS OF VERTEBRATES  The Heart and Circulatory Systems of Vertebrates § Fishes have 2-chambered heart: atrium and ventricle. § Pulmonary (respiratory) and Systemic circulation are not separate § The system is single circulation circuit because the blood only passes the heart once § Amphibians and most reptiles have 3-chambered heart: 2 atria and 1 ventricle § evolution of a double circulatory circuit in which blood passes through the heart twice during its circuit through the body § In reptiles, the ventricle is partially divided into a right and left side § Crocodilians, birds and mammals have 4-chambered heart: 2 atria and 2 ventricles § Complete anatomical separation of ventricles. This facilitates the double circulation required to maintain high blood pressure. § 2 main circuits of blood circulation: § Pulmonary circuit § Systemic circuit Circulatory Systems of Vertebrates Circulatory Systems of Vertebrates  The Mammalian Heart § a hard-working pump that moves blood throughout the body § The heart of an average human beats 70 times/minute- more than 100,000 times per day. In a 70-year lifetime, the heart beats more than 2.6 billion times without fatiguing. § In general, small animals have higher heart rate than larger animals. This is due to higher metabolic rate that occurs with a decrease in body size. For example, an elephant’s heart rate is about 25 times/ minute while a mouse beats 400 beats per minute. § Walls of the heart § Epicardium- external layer § Myocardium § middle layer; thick cardiac muscle which gives the heart its special pumping ability § Endocardium § inner layer; thin layer of connective tissue  Chambers of the Heart § Two superior chambers: receive blood from veins § Right atrium receives blood from: § superior vena cava § inferior vena cava § coronary sinus § Left atrium receives blood through the: § 4 pulmonary veins, which drain blood from the lungs. § Interatrial septum- the partition between two atria  Chambers of the Heart § Two inferior chambers: major pumping chambers. § They eject blood into the arteries and force it to flow through the circulatory system. § Right ventricle pumps blood into the pulmonary trunk. § Left ventricle pumps blood into the aorta. § Interventricular septum § Partition between ventricles  Valves of the Heart § Atrioventricular (AV) valves- valves between the atrium and ventricle § Tricuspid valve § between the right atrium and right ventricle § Bicuspid (mitral) valve § between left atrium and left ventricl § Semilunar valves- valves between the ventricle and an artery § Pulmonic valve § between the right ventricle and pulmonary trunk § Aortic valve § between the left ventricle and aorta  Pulmonic and Systemic Circulations § Blood from all parts of the body goes to superior vena cava (from upper parts) and inferior vena cava (from lower parts)à right atriumà tricuspid valveà right ventricleà pulmonic valveà pulmonary trunk (artery)à lungsà pulmonary veinsàleft atriumà bicuspid (mitral) valve)à left ventricleà aortic valveà aortaà different parts of the body § Pulmonic circulation- From superior and inferior vena cavas to the lungs and back to the left atrium § Systemic circulation- From the left ventricle to the tissues of the body and back to the superior and inferior vena cavas to the right atrium. Pulmonic and Systemic Circulations  Types of Circulation § Pulmonary circuit (or circulation) § carrying unoxygenated blood from the heart (right ventricle) to the respiratory (alveolar) surfaces of the lungs and oxygenated blood back to the heart (left atrium) § The right side of the heart pumps blood to the lungs and back to the left side of the heart § Systemic circuit (or circulation) § carrying oxygenated blood from the heart (left ventricle) to all parts of the body except the respiratory surfaces of the lungs and unoxygenated blood back to the heart (right atrium) § The left side of the heart pumps blood to all other tissues of the body and back to the right side of the heart  Phylogenetic Trends in the Circulatory System § Diffusion and bulk flow § Two-chambered heart § Porifera (Closed) § Cnidaria § Cartilaginous fishes § Platyhelminthes § Bony fishes § Nematoda § Three-chambered heart § Closed Circulatory Systems (Closed) § Annelida § Amphibians § Cephalopoda § Most reptiles § Open Circulatory Systems § Four-chambered heart § Mollusca (except (Closed) Cephalopoda) § Crocodilians § Arthropoda § Birds § Echinodermata § Mammals