Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Circulatory & Respiratory Systems Ch’s. 23 & 24 Three types of circulatory systems found in the animal kingdom Open and Closed Circulatory Systems • Two Types 1. open circulatory system • there is no distinction between the circulating fluid (blood) and the extracellular fluid of the body tissues (interstitial fluid or lymph) • this fluid is called hemolymph 2. closed circulatory system • the circulating fluid (blood) is always enclosed within blood vessels that transport blood away from and back to a heart • arteries carry blood away from the heart, and veins return blood to the heart; blood passes from the arterial system to the venous system in capillaries • the pressure of the blood forces some fluid out of the capillary walls – this fluid is called interstitial fluid » some of it will return to the blood but some becomes lymph and travels through the lymph vessels Open and Closed Circulatory Systems • The functions of the circulatory system can be divided into three areas transportation • substances essential for cellular functions are transported by the circulatory system regulation • the cardiovascular system participates in temperature regulation, such as by countercurrent heat exchange protection • the circulatory system protects against injury and foreign microbes or toxins introduced into the body Architecture of the Vertebrate Circulatory System • The vertebrate circulatory system (also known as the cardiovascular system) is made up of three elements heart—a muscular pump that pushes blood through the body blood vessels—a network of tubes through which the blood moves blood—fluid that circulates through the vessels Architecture of the Vertebrate Circulatory System • Blood moves through the body in a cycle, from the heart, through a system of vessels blood leaves the heart in arteries from the arteries, blood passes into smaller arterioles tiny vessels called capillaries connect arterioles to venules, or small veins venules and then veins carry blood back to the heart The capillary network connects arteries with veins Architecture of the Vertebrate Circulatory System • An artery is more than a simple pipe it needs to be able to expand with be strong against the pressure caused by contraction of the heart for this reason, arteries have both elastic and smooth muscle layers • Arterioles differ from arteries in that they are smaller in diameter and respond to nervous and hormonal stimulation they can constrict or expand to affect blood flow during periods of stress or body activity The structure of blood vessels Capillary Structure Figure 29.4 (b) The structure of blood vessels Figure 29.5 Red blood cells within a capillary Structure of Veins Figure 29.4 (c) The structure of blood vessels Figure 29.6 Veins and arteries Figure 29.7 Flow of blood through veins The Lymphatic System: Recovering Lost Fluid • The cardiovascular system is very leaky from capillary exchange, the body loses about 4 liters of fluid each day to collect and recycle this fluid, the body uses a second circulatory system called the lymphatic system • the lymphatic system is also a network of vessels filled with a fluid called lymph • ultimately the lymph reenters the bloodstream through veins in the neck The human lymphatic system The Lymphatic System: Recovering Lost Fluid • The lymphatic system has three important functions it returns proteins to circulation • if this protein remains in the tissues, it would cause swelling or edema it transports fats absorbed from the intestine it aids in the body’s defense • swellings along lymph vessels called lymph nodes and a lymph organ called the spleen are where bacteria and dead blood cells are destroyed • the thymus produces white blood cells Blood • Blood plasma is a complex solution of water with three kind of substances dissolved in it metabolites and wastes • for example—glucose, vitamins, hormones, wastes salts and ions • the chief plasma ions are sodium, chloride, and bicarbonate proteins • proteins help keep water in the plasma • other plasma proteins include antibodies, globulins, and fibrinogen Blood • Nearly half the volume of blood is occupied by cells the three principal cell types are • erythrocytes (red blood cells) – the blood’s hematocrit is the fraction of the total volume of the blood that is occupied by red blood cells – in humans, the hematocrit is usually about 45% • leukocytes (white blood cells) • platelets (cell fragments) Amphibian and Reptile Circulation • The advent of lungs involved a major change in the pattern of circulation after blood is pumped by the heart to the lungs, it does not go directly to the tissues of the body but instead returns to the heart • pulmonary circulation goes to and from the heart and lungs • systemic circulation goes to and from the heart and the rest of the body Amphibian and Reptile Circulation • The amphibian heart has structural features to prevent the mixing of deoxygenated from the body with oxygenated blood from the lungs the atrium is divided by a septum that separates the blood coming from the body and from the lungs Amphibian and Reptile Circulation • Amphibians in water supplement the oxygenation of their blood by obtaining additional oxygen by diffusion across their skin this is called cutaneous respiration • The reptilian heart is additionally specialized there is a partial septum in the ventricle the conus arteriosus has become incorporated into the large arteries leaving the heart Mammalian and Bird Circulation • mammals, birds, and crocodiles have a four-chambered heart with two complete pumping circuits this increased efficiency of the double circulation in mammals and birds may have been important in the evolution of endothermy • more efficient circulation is necessary to support the high metabolic rate required Mammalian and Bird Circulation • In the mammalian heart, oxygen-rich blood returns from the lungs through pulmonary veins to the left atrium of the heart and flows mostly passively through the mitral valve into the left ventricle the thick-walled left ventricle contracts, sending oxygenated blood through a large artery called the aorta and out to the body • backflow of blood from the aorta is prevented by the aortic semilunar valve blood travels through the body returns to the heart through the vena cavae, which drain into the right atrium blood flows from the right atrium through the tricuspid valve to the right ventricle the right ventricle contracts, pushing blood through the pulmonary valve into pulmonary arteries that lead to the lungs The heart and circulation of mammals and birds The heart and circulation of mammals and birds Respiratory Systems • Respiration is the uptake of oxygen and the simultaneous release of carbon dioxide most primitive animal phyla obtain oxygen directly from their environments through diffusion more advanced phyla have specific respiratory organs • gills, tracheae, and lungs Respiration in Terrestrial Vertebrates • Lungs are less efficient than gills because new air that is inhaled mixes with old air already in the lung but there is so much more oxygen in air than in water the lungs of mammals possess on their inner surface many small chambers called alveoli, which greatly increases surface area for the diffusion of oxygen The Mammalian Respiratory System • In the mammalian respiratory system, air passes in and out of the lungs, which are housed in the thoracic cavity • air is warmed and filtered as it flows through the nasal cavity • it passes next through the pharynx, then the larynx (or voice box), then to the trachea, or windpipe. • from there, air passes through several branchings of bronchi in the lungs and then to the bronchioles – the tissue of the lungs is divided into tiny air sacs called alveoli; through these thin-walled cells, gas exchange with the blood occurs The human respiratory system The Mammalian Respiratory System • The mammal respiratory apparatus is simple in structure and functions as a one-cycle pump a diaphragm muscle separates the thoracic cavity from the abdominal cavity each lung is covered by a thin, smooth membrane called the pleural membrane this membrane adheres to another pleural membrane lining the walls of the thoracic cavity, basically coupling the lungs to the thoracic cavity The Mammalian Respiratory System • Air is drawn into the lungs by the creation of negative pressure • The active pumping of air in and out is called breathing during inhalation, muscular contraction causes the chest cavity to expand during exhalation, the ribs and diaphragm return to their original position How breathing works How Respiration Works: Gas Exchange • Oxygen moves through the circulatory system carried by the protein hemoglobin hemoglobin molecules contain iron, which binds oxygen in a reversible way Figure 30.8 The hemoglobin molecule How Respiration Works: Gas Exchange • Hemoglobin molecules act like little sponges for oxygen at the high O2 levels that occur in the blood supply at the lung, most hemoglobin molecules carry a full load of O2 in the tissues, the O2 levels are much lower, so hemoglobin gives up its bound oxygen in the presence of CO2, the hemoglobin assumes a different shape that give up its oxygen more readily How Respiration Works: Gas Exchange • CO2 must also be transported by the blood about 8% simply dissolves in the plasma 20% is bound to hemoglobin but at a different site than where O2 binds the remaining 72% diffuses into the red blood cells • In order to maintain the gradient for CO2 to leave the tissues and enter the plasma, the CO2 levels in the plasma must be kept low The Nature of Lung Cancer • Smoking causes lung cancer the annual incidence of lung cancer is much higher for smokers than for nonsmokers changes in the incidence of lung cancer have mirrored changes in smoking habits many types of mutagens are found in cigarette smoke that can damage genes • the p53 gene is damaged in 70% of lung cancers smoking also leads to nicotine addiction