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Ch 49 & 50
Gas exchange and the circulatory system in animals
| Question | Answer |
|---|---|
| How does O2 and CO2 relate to cellular respiration? | cells require O2 from the environment to produce ATP by cellular respiration. Cell resp. produces CO2 as an end product, which must be lost to the environment to prevent toxic effects |
| How does O2 and CO2 exchange gases? | diffusion |
| What does the air pathway in humans consist of? | An oral/nasal cavity, followed by the pharynx. The larynx, which leads to the trachea which branches into two bronchi. The bronchi branch into bronchioles, which terminate in the alveoli |
| explain the mucus escalator | cells lining the airways produce a sticky mucus that captures dirt and microbes. the mucus is cleared by cilia beating upward toward the trachea and pharynx, where it is swallowed |
| what is cystic fibrosis? | a faulty chloride channel leads to mucus that is thick and difficult to clear, resulting in blockage and infection |
| what is a surfactant | a chemical substance that reduced the surgace tension of a liquid. |
| What is the surfactant of the lung? | the aquaeous lining of the lung has surface tension that must be overcome to permit inflation |
| What do cells in the alveoli produce when they are stretched? | surfactant molecules |
| What may happen to premature babies if they are born before cells in the alveoli are producing surfactant? | they may develop respiratory stress syndrome |
| Explain how the human lungs are positioned | they are suspended in the thoracic cavity in separate, closed pleural cavities |
| What is the thoracic cavity bounded by? | the shoulder girdle, rib cage, and diaphragm |
| How does the diaphragm conduct air flow in the lungs? | with inhalation, the diaphragm muscle contracts downward to create suction and air flows into the lungs. When the diaphragm relaxes, it pushes upward and exhalation occurs |
| How does the ribcage allow for breathing? | intercostal muscles lift the ribs up and down to increase thoracic cavity volume |
| What happens as oxygen diffuses from alveoli into the blood? | it is swept away and delivered to the cells and tissues of the body |
| What is hemoglobin? | a protein consisting of four polypeptide subunits each with a heme (iron containing) group. Most O2 is carried by the oxygen-binding pigment in red blood cells |
| What deadly poison destroys the ability of hemoglobin to transport oxygen? | carbon monoxide (CO) binds to hemoglobin with a much higher affinity than does oxygen |
| What is myoglobin? | an oxygen-binding molecule that can take up one molecule of oxygen. It has a higher affinit for O2 than hemoglobin and provides an oxygen reserve for high metabolic demand or when blood flow is interrupted |
| Describe CO2 | highly soluble, moving easily through cell membranes into the blood, where the partial pressure of CO2 is lower. Most CO2 is transported as a bicarbonate ion |
| What is the circulatory/cardiovascular system composed of? | a pump (heart), fluid (blood), conduits (blood vessels) |
| Describe the two separate pumps of the human heart | the left pump delivers blood to the systematic circuit, the right pump delivers blood to the pulmonary circuit |
| What are the atrioventricular valves? | between the atria and ventricles, prevent backflow into the atria when the ventricles contract |
| Which valves prevent backflow into the ventricles? | the pulmonary valve and the aortic valve |
| Where does the right atrium recieve blood from? | the superior and inferior vena cavas. From the right atrium, blood goes to the right ventricle |
| Where does the right ventricle send blood? | through the pulmonary artery to the lung |
| What do pulmonary veins do? | return oxygenated blood to the left atrium, from the left atrium blood goes to the left ventricle |
| Where does the left ventricle send blood? | through the aorta to the body and the capillary beds |
| How does blood return again to the right atrium? | via veins |
| Why is the left ventricle more muscular? | because the resistence of the systematic circuit is much greater than that of the pulmonary circuit |
| Describe the cardiac cycle | ventricle contraction is called systole, ventricle relaxation is called diastole at the end of diastole, the atria contract |
| What are the sounds of the cardiac cycle caused by? | closure of the heart valves |
| What sound does defective heart valves produce? | heart murmurs, whooshing sounds following the lub |
| What is artery pulsation? | the cardiac cycle can be felt in artery pulsation, the surge of blood during systole |
| How are cardiac muscle cells in contact with one another? | the cells are in electrical contact with one another through gap junctions. This permits coordinated contraction for effective blood pumping |
| What is the sinoatrial node? | the primary pacemaker of the heart located at the juncture of the superior vena cava and right atrium |
| What is the atrioventricular node? | stimulated by depolarization of the atria; with a slight delay it generates action potentials that are conducted to the ventricles via a bundle of fibers called the bundle of His |
| Explain artery structure | large artery walls are elastic to withstand high pressures & squeeze blood by elastic rebound. Smooth muscle cells contract/relax, varying the vessel diameters. resistence to flow also changes, allowing blood to be distributed to different tissues |
| What are capacitance vessels? | another name for veins, because of their high capacity to store blood |
| What is atherosclerosis and what are some effects? | hardening of the arteries; heart attack and stroke |
| What happens when smooth internal lining of arteries become damaged? | deposits of plaque form at damaged sites |
| What is a thrombus? | a blood clot - occurs when blood platelets stick in the plaque further blocking the artery |
| How can a heart attack occur? | if a thrombus (coronary thrombosis) blocks an artery, a heart attack (myocardial infarction) can occur |
| How can a stroke occur? | if part of the thrombus breaks away (embolism), lodges in the brain and blocks blood flow |
| What are some risk factors for heart disease? | high fat/high cholesterol diet, smoking, a sedentary life style, and obesity |
| What type of tissue is blood? | connective tissue, consisting of living cells within an extracellular matrix called plasma |
| What is the structure of blood? | the cellular components of blood are the red blood cells (erythrocytes) the white blood cells (leukocytes) and the platelets (cell fragments) |
| What is the difference between prothrombin and thrombin? | prothrombin is the inactive enzyme that is converted into its active form (thrombin) due to cell damage and platelet activation |
| What does thrombin do? | causes a plasma protein fibrinogen to polymerize, forming fibrin threads. These threads form a meshwork to seal the damaged vessel and provide a base for scar tissue |
Created by:
cassidylm34
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