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Learn about closed and open circulatory systems in invertebrates, vertebrate circulation, blood vessels, human heart, cardiac cycle, respiration, gas exchange mechanisms, gills, tracheal systems in insects. Explore the vital link between the respiratory and circulatory systems.
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INVERTEBRATE CIRCULATION • Two types of invertebrate circulation: • Open circulation • Closed circulation • Both have three basic components: • A circulatory fluid (blood), a set of tubes (blood vessels), and a muscular pump (heart).
CLOSED CIRCULATORY SYSTEM • Blood is confined to vessels and is distinct from the interstital fluid. • Materials are exchanged by diffusion between the blood and the interstital fluid bathing the cells. • Earthworms, squids, octopuses, and all vertebrates have closed circulatory systems.
OPEN CIRCULATORY SYSTEM • There is no distinction between blood and hemolymph. • One or more hearts pump the hemolymph into an interconnected system of sinuses, which are spaces around organs. • Here chemical exchange occurs between lymph and body cells.
VerteBRATE Circulation • Often called the cardiovascular system. • The vertebrate heart has one or two atria • The chambers that receive blood returning to the heart. • One or two ventricles • The chambers that pump blood out of the heart.
Blood vessels • Three main kinds: • Arteries- carry blood away from the heart to organs throughout the body and branch into arterioles- small vessels that convey blood to capillaries. • Veins-a vessel that returns blood to the heart. • Capillaries- microscopic vessels with very thin, porous walls. • Networks of these vessels, called capillary beds, infiltrate each tissue.
The Human HEART • The human heart is made up of 4 chambers. • The two atria have relatively thin walls and serve as collection chambers for blood returning to the heart. • The ventricles have thicker walls- the left ventricle pumps blood to all body organs.
The cardiac Cycle • One complete sequence of pumping and filling. • The contraction phase of the cycle is called systole, and the relaxation phase is diastole. • The volume of blood per minute that the left ventricle pumps out into the systemic circuit is called cardiac output. • Cardiac output depends on heart rate and stroke volume.
Blood circulation • Blood delivers nutrients and removes wastes throughout an animal’s body. • Blood travels over a thousand times faster in the aorta than in capillaries.
Respiration • There are many systems in the bodies of animals, each of which serve a very important purpose without which we wouldn’t exist. The Respiratory System however serves a purpose that is not too difficult to understand. The Respiratory System and the Circulatory System are directly linked. Each of these relies on the other. If one fails, so does the other. • Respiration is the actual act of gas exchange. Although some may think this is a simple process, it is important to note that it is much more complicated.
Gas Exchanging Mechanisms • There are different types of gas exchanging mechanisms in animals depending on their natural habitat. • Fish, because they live in aquatic biomes, adapted organs called gills where gas exchange takes place. • Insects, being simpler organisms than mammals, have a tracheal system. This is a system of tubes that branch throughout the body. • Mammals and birds have developed organs called lungs. Lungs are different than tracheal systems in insects in that they are located in one designated in location and do not branch out to the entire body. That is why animals with lungs also have a circulatory system.
Gills • Gills are outfoldings in the bodies of fish. Fish have such a different respiratory system than land animals because they rely on obtaining their oxygen from water as opposed to air. Oxygen is much more scarce in water, especially the deeper you go where there is less phytoplankton producing oxygen in the water. • Fishes gills do something called ventilation. Ventilation is the process by which water enters a fish’s mouth, passes through the pharynx, flows over the gills and exits the body. • Fish spend a lot of energy during ventilation because the oxygen per unit of volume is very low, and they must obtain as much as possible. • Fishes bodies have developed a mechanism called countercurrent exchange. This mechanism is very effective and ensures that fish consume the least amount of energy as possible when they are undergoing respiration. Basically the blood in a fish’s body flows opposite to the movement of water past the gills so that the maximum amount of oxygen can be picked up.
Tracheal Systems in Insects • This is a system of air tubes that branch throughout the body. • Larger tubes called tracheae open to the outside. • All of the body’s cells are within a short distance from the respiratory medium. • This system suffices for small insects because the trachea brings in enough oxygen and gets rid of enough carbon dioxide to support cellular respiration. • Larger insects must ventilate their tracheal systems with rhythmic body movements.
Mammalian Respiratory Systems • Mammalian lungs are located in the thoraic cavity and have a spongy texture. They have a moist epithelium which is the respiratory surface. • In mammals the trachea and the esophagus are right next to each other, so there must be a system to separate air from food. Whenever food is swallowed the larynx moves up so that the epiglottis seals with the glottis. Imagine if your windpipe and esophagus were constantly open simultaneously? • The vocal cords are located in the larynx. Sound is produce when muscles in the voice box are tensed. These muscles are stretched so that they vibrate.
Mammalian Respiratory Systems • The trachea eventually branches into two bronchi which lead to each lung. • As soon as we get into the lung, each bronchus separates into thinner and finer tubes called bronchioles. • At the end of all the bronchioles are clusters of air sacs called alveoli. It is on the moist epithelial surface of the millions of alveoli found in lungs that gas exchange occurs.
Breathing Ventilates the Lungs • The process that ventilates the lungs is called breathing. Breathing consists of the inhalation and exhalation of air. • Mammals ventilate their lungs through a process called negative pressure breathing. This basically works like a suction pump that sucks air into the lungs instead of pushing into the lungs. • Mammalian breathing relies on muscles that change the volume of the rib cage and chest cavity. • The muscle responsible for changing the chest cavity’s volume is called the diaphragm. It is a sheet of skeletal muscle which forms the bottom layer of the chest cavity.
How a Bird Breathes • Ventilation is much more complex in birds than in mammals. Birds have about nine air sacs separate from the lungs that are used to trap air. • The air sacs are just pathways to the lungs. The lungs are where the official gas exchange occurs. • Instead of alveoli, birds have tiny channels called parabronchi. Air flows through parabronchi in one direction.
Control of Breathing in Humans • Breathing in humans is a voluntary and involuntary action. Although we can control the rate at which we breath there are automatic mechanisms that regulate our breathing. • The breathing control centers are located in two distinct regions of the brain, the medulla oblongata and the pons. • Secondary control over breathing is exerted by sensors in the aorta and carotid arteries that monitor oxygen and carbon dioxide concentrations in the blood as well as blood pH.
The Role of Partial Pressure Gradients • Diffusion of a gas depends on differences in a quantity called partial pressure. • A gas always diffuses from an area of higher to lower pressure. • Blood that arrives at the lungs via the pulmonary arteries has a lower pressure of oxygen and higher pressure of carbon dioxide.
Respiratory Pigments • Since oxygen has a low solubility in water a problem is posed to animals that rely on the circulatory system to deliver oxygen. • Most animals transport most of their oxygen bound to certain proteins called respiratory proteins instead of in dissolved form.
Respiration Activity • The part of an animal’s body where gases are exchanged with the surrounding environment is called the ________________. • _______________ is the mechanism through which blood flows in the opposite direction of blood flow. • The _______________ is made up if air tubes that branch through the entire body. • These sites of gas exchange called ________ are restricted to one location. • The ________ moves upward in order to tip the epiglottis over the glottis. • Exhaled air rushes by a pair of ____________ in the larynx. • From the larynx, air passes into the _________. • The tinies bronchioles dead-end as a cluster of air sacs called ________. • Lung volume increases as a result of contraction of the rib muscles and the _________. • The volume of air a mammal inhales and exhales with each breath is called _____________.
Activity Answers • Respiratory Surface • Countercurrent Exchange • Tracheal System • Lungs • Larynx • Vocal Cords • Trachea • Alveoli • Diaphragm • Tidal Volume
The Immune System The body has two mechanisms in defending itself: Nonspecific defense mechanism and specific defense mechanism. It is then subdivided into three lines of defenses.
Nonspecific Defense Mechanism • First line of defense. • Is external and consists of epithelial tissues that cover and line our bodies and the secretions they produce. • Examples are skin and mucous membrane. Key terms: Antimicrobial proteins: function in nonspecific defense either by attacking microbes directly or by impeding their production. Complement System: a group of at least 20 blood proteins that cooperate with other defense mechanism. It amplifies the inflammatory response, enhances phagocytosis, and directly lyses pathogens.
Second line of defense • Is internal. • It is triggered by chemical signals and involves phagocytic cells and antimicrobial protein that indiscriminately attacks invaders that penetrates the body’s outer barriers. • Inflammation is a sign of this defense. • Includes phagocytic white blood cells, antimicrobial proteins, and the inflammatory response. Key Terms: Phagocytosis: the injection of invading organisms by certain types of white cells. Neutrophills: white blood cells; cells damaged by invading microbes release chemical signals that attract neutrophils from the blood. They enter infected tissue,engulfing and destroying microbes there. Macrophages: are the largest phagocytic cells. They engulf a microbe in vacuole that fuses with a lysosome. Natural Killer (NK) cells: destroy virus infected body cells • Inflammatory response: a line of defense triggered by penetration of skin or mucous membranes in which small blood vessels in the vicinity of an injury dilate and become leakier, enhancing filtration of leukocytes. • How is the inflammatory response initiated? • Chemical signals such as histamine are released by cells of the body in response to tissue injury. NK cells
Specific Defense Mechanism • Third line of defense • Known as The Immune System; it works simultaneously with the second line of defense, but it responds in a specific way to particular microorganisms, aberrant body cells, toxins, and other substances marked by foreign molecules. • Includes the production of proteins called antibodies and involves a diverse group of blood cells called lymphocytes.
Lymphocytes • B lymphocyte (B Cell):a type of lymphocyte that develops in the bone marrow and later produces antibodies. • T lymphocyte (T Cell): a type of lymphocyte responsible for cell-mediated immunity that differentiates under the influences of the thymus. Both B Cell and T Cell circulate throughout the blood and lymphocytes and are concentrated in the spleen, lymph nodes, and other lymphatic tissues. Specific. Why? Because lymphocytes recognize and respond to particular microbes and foreign molecules. How? T cell
Antigen: a foreign macromolecule that does not belong to the host organism and that elicits an immune response. • Antibody: an antigen-binding immunoglobulin, produced by B Cells, that functions as the effector in an immune response Antigen receptors: transmembrane versions of antibody molecules that B Cells and T Cells use to recognize specific agents. • Effector Cell: a muscle cell or gland cell that performs the body’s responses to stimuli. • Memory Cells: long-lived cells bearing receptors for the same antigen.
Immunity • Acquired Immunity: highly specific; develops only after the body is exposed to inducing agents • Innate Immunity: nonspecific; present before any exposure to pathogens and is effective from the time of birth.
Activity 1 : Immune System Word Bank Complete Sentences ___________ are the largest phagocytic cells that extend long pseudopodia that can attach to polysaccharides on a microbes surface. 2. Damage to tissue by a physical injury or by the entry of microorganisms triggers a localized ___________, increasing the local blood supply. 3. Attract phagocytes to an area and is secreted by endothelial cells blood vessels and monocytes, are called__________ molecules. 4. ____________ are short lived cells that combat the same antigen. 5. Long lived cells bearing receptors specific for the same antigen._____________. 6. How many lines of defense are there ___. 7. Cells damaged by invading microbes release chemical signals that attract _________from the blood. 8.________ is produced by circulating leukocytes . 9._______T lymphocytes kill cancer cells and cells infected by viruses. Effector Cells Macrophages Histamine Chemokines Neutrophils Cytotoxic Inflammatory response Memory cells 3
Activity 2: Immune System True or False 1.Lymphocytes are a part of the second line of defense. 2.Anti-microbal proteins are the first line of defense. 3.B cells are a type of lymphocyte. 4. Natural killers do not attack o the viruses membrane and cause the cell to lyse. 5.Inflammatory response is initiated by chemical signals. 6.Interestrial fluid is found in blood vessels. 7.Only B cells circulate throughout the blood. 8. Antigens do not interact with specific lymphocytes, its at random. 9. Lysozymes digest the cell walls of many bacteria. 10.The complement system carries out steps that lead to the lyses of microbes.
Answer Activity1: • Macrophages • Inflammatory response • Chemokines • Effector cells • Memory cells • 3 • Neutrophils • Histamine • Cytotoxic • Activity 2 • False • False • True • False • True • False • False • False • True • True
