BIOL 103 Final: REVIEW: Circulatory and Cardiovascular Systems

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24 Jul 2016
Circulatory and Cardiovascular Systems
Open circulatory system: a circulatory system in which fluid called hemolymph bathes the tissues and organs directly and there is no
distinction between the circulating fluid and the interstitial fluid
Closed circulatory system: a circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid
Lymphatic system: a system of vessels and nodes, separate from the circulatory system, that returns fluid, proteins, and cells to the blood
Cardiovascular System
oTransport of gases between environment and tissues (oxygen to tissues, carbon dioxide from tissues)
oTransport of nutrients and metabolic waste products
oDefence – immune system
Blood Components
Blood Clotting
oBreak in blood vessel wall exposes proteins that
attract platelets and initiate coagulation
oCoagulation: conversion of liquid components of
blood to a solid clot
oCoagulant/sealant circulates in inactive form
oIn response to cut, platelets clump to cut and
release clotting factors that trigger conversion of
plasma protein prothrombin to active form
oProthrombin (zymogen)  Thrombin:
(endoprotease)… calcium is needed
oThrombin (enzyme) that catalyzes conversion of
fibrinogen to fibrin
oFibrin aggregates into threads that form framework/meshwork of clot
othrough positive feedback, thrombin activates production of more thrombin
Hemophilia disease: excessive bleeding and bruising from even minor cuts and bubs
Thrombus: blood clot within a blood vessel
oanticlotting factors in blood normally prevent spontaneous clotting in absence of an injury
Red Blood Cells
o300 million molecules of hemoglobin in each red blood cell
ohemoglobin is a tetramer (2 beta globins and 2 alpha globins) and has 4 heme groups
ooxygen binds to the four heme groups (each cell can carry 10^9 oxygen)
oair is 21% oxygen, 78% nitrogen, less than 1% carbon dioxide and other gases
oatmospheric pressure on body surfaces is 1kPa or 7.5 mmHg
oDalton’s law: total pressure is the sum of partial pressures
oPartial pressure: pressure exerted by a particular gas in a mixture of gases
oatmospheric pressure is the sum of the partial pressure (pressures exerted by each gas in air in proportion to their
oPO2 = 0.21 x760 mmHG (sea level) = 160 mmHg
Gas Exchange
odiffusion across cell membranes is driven by partial pressure gradients, gases move from high concentration to low
oPressure of oxygen is low in capillary beds, oxygen diffuses across alveoli membranes and picked up by hemoglobin
oHemoglobin most efficient way of carrying oxygen, some in plasma
oSome CO2 carried in plasma, some in red blood cells when released from tissues
oCO2 + H2O  H2CO3  H+ + HCO3-
oCarbonic acid
oCO2 on hemoglobin released because of partial pressure of carbon dioxide
oHemoglobin all or nothing, 4 or none
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