Exam 4 Study GuideBSC2010- BatesObjectives for Lecture 29: Intro to Physiology and the Circulatory System • Understand that diffusion is the major mechanism for the movement of substances in organisms, that diffusion rate is a function of surface area and the distance over which diffusion must occur. - diffusion is rapid only over small distances- diffusion is slow for distances of more than a few millimeters- rate of diffusion = (area X concentration gradient)/distance• That a circulatory system is required (for delivery of nutrients and removal of wastes) whenever cells are more than 1 mm from an external surface. -The circulatory system moves fluid between each cell’s immediate surroundings and the tissues where exchange with the environment occurs- the minimize the distance that substances must diffuse to enter or leave a cell-the heart powers circulation by using metabolic energy to elevate the hydrostatic pressure of the circulatory fluid, which then flows through a circuit of vessels and back to the heart• Know the difference in structure between open and closed circulatory systems. Know the meaning of the terms hemolymph, interstitial fluid, and blood. - open circulatory system: circulatory fluid bathes the organs directly Most arthropods and mollusks have these The circulatory fluid is called hemolymph and is also the interstitial fluid Contraction of one or more hearts pumps the hemolymph through the vessels into interconnected sinuses, spaces surrounding the organs Within the sinuses, chemical exchange occurs between the hemolymph and the body cells Relaxation of the heart draws hemolymph back in through pores, and body movements help circulate the hemolymph by periodically squeezing the sinuses Have a lower hydrostatic pressure which saves energy- Closed circulatory system: blood is confined to vessels and is distinct from the interstitial fluid Includes annelids(earthworms), cephalopods (squids/octopus), and all vertebrates One or more hearts pump blood into large vessels that branch into smaller ones coursing through the organs Materials are exchanged between the smallest vessels and the interstitial fluid bathing the cells Benefits include high blood pressure which enable the effective delivery of oxygen and nutrients to the cells of larger and more active animals Called the cardiovascular system• Know that transport in the vertebrate circulatory system is pressure driven and understand the relationship between flow rate, pressure, and resistance. - Water is an incompressible fluid; when pressure is applied to it a hydrostatic pressure results- Water flows from regions of high pressure to ones of lower pressure- Blood flow= ∆P/R∆P is the pressure difference between two points Resistance increases with decreasing diameter of the vessels-• Know the organization of the circulatory systems with two, three, and four chambered hearts, which vertebrate groups have which, and how the three and the four chambered hearts increased efficiency of the circulatory system. - Atria: chambers that receive blood entering the heart- Ventricles: chambers responsible for pumping blood out of the heart- Pulmonary circuit- capillary beds involved are all in the lungs- Pulmocutaneous circuit- includes capillaries in both the lungs and the skin- Two chambers- atrium + ventricle- Three chambers- left & right atrium +one ventricle Amphibians A ridge within the ventricle diverts most of the oxygen poor blood from the right atrium into the pulmocutaneous circuit and most of the oxygen-rich blood from the left atrium into the systematic circuit Reptiles (except birds) A septum partially divides the ventricle into seperate right and left chambers- Four chambers- two atria and two ventricles Mammals and birds The left side of the heart receives and pumps only oxygen-rich blood, while the ride side receives and pumps only oxygen-poor blood These endotherms use about ten times as much energy as ectotherms; therefore their circulatory systems needs to deliver about ten times as much fuel and oxygen to their tissues (and remove that much CO2 and waste) This large traffic of substances is made possible by seperate and independently powered systematic and pulmonary circuits and by large hearts that pump the necessary volume of blood• Know the parts of the mammalian heart and the pattern of blood flow in our circulatory system. - Refer to page 903 in the text• Know the contraction pattern and be able to correctly use the terms diastole and systole. -much of the blood entering the atria flows into the ventricles while all heart chambers are relaxed- Contraction of the atria transfers the remainder before the ventricles begin to contract- Ventricles have thicker walls and contract much more forcefully than the atria-especially the left ventricle which pumps blood to all body organs through the systemic circuit-despite the greater contraction, the left and right ventricle pump the same volume of blood during each contraction- cardiac cycle- once complete cycle of contracting (pumping blood) and relaxing (filling with blood)- the contraction phase is called systole- the relaxation phase is called diastole- the volume of blood each ventricle pumps per minute is the cardiac output Two factors determine this: The rate of contraction- heart rate And the stroke volume- the amount of blood pumped by a ventricle in a single contraction• Know the function of the sinoatrial node (pacemaker region) and the AV (atrioventricular) node in controlling heart contraction. - Four valves in the heart prevent backflow and keep blood moving in the correct direction: Atrioventricular (AV) valve lies between each atrium and ventricle; anchored by strong fibers that prevent them from turning inside out; pressure generated by the powerful contraction of the ventricles closes the AV valves, keeping blood from flowing back into the atria Semilunar valves are located at the two exits of the heart: where the aorta leaves the left ventricle and where the pulmonary artery leaves the right ventricle; these are pushed open by the pressure generated during contraction of the ventricles; when the ventricles relax, pressure built up in the aorta closes the semilunar valves and prevents significant backflow The heart beat sound is “lub-dup, lub-dup”; the “lub” part is created by the recoil of blood against the closed AV valves and
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