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BIO 141 Lecture 7 notes

by: Camryn McCabe

BIO 141 Lecture 7 notes Biol 141

Marketplace > Science > Biol 141 > BIO 141 Lecture 7 notes
Camryn McCabe
Penn State
GPA 3.81

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notes from lecture 7
Janelle Malcos
Class Notes
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This 5 page Class Notes was uploaded by Camryn McCabe on Friday February 19, 2016. The Class Notes belongs to Biol 141 at a university taught by Janelle Malcos in Spring 2016. Since its upload, it has received 30 views.

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Date Created: 02/19/16
Cardiovascular System Lecture 7 notes  Consists of: o Heart  Consists of 2 types of cardiac cell (muscle and conductive) and fibrous cells o Associated blood vessels  Consist mainly of smooth muscle  Functions: o Transport of gases, nutrients, waste o Regulation of blood pressure  Heart: muscle cells bound to a fibrous tissue o Skeleton of heart: valves and associated structures  Fibrous (form of connective tissue; helps make things stretchy/elastic) skeleton  Functions:  Structural support for the heart  Provides something for muscle cells to pull against  Electrical insulation that helps regulate heart beat o Organized structure  Starts as a tube (during embryonic development)  Muscle of the heart can be “unwound” from its mature form  Complex organization allows for contraction of chambers to move blood o 2 types of cardiac cells  1- cardiomyocytes (muscle cells)  Striated, branched, can be excited and can excite each other, can contract  2- conductive cells  Initiate and communicate action potentials for heart beat  These 2 work together to cause heart contraction based on action potentials o Intercalated discs- collection of proteins that connect cardiac cells at branch points  1. Desmosomes  Provide a physical connection between neighboring cells  Allows muscle cells to pull on each other without damaging membrane (w/o pulling them apart) Cardiovascular System Lecture 7 notes  2. Gap junctions  Provide cytoplasmic connection  Made of proteins that are non-specific leak- channels  Allow sodium to diffuse between cells during depolarization o Results in excitation of neighboring cells and propagation of action potentials o Chambers of the heart  4 chambers exist that collect and pump blood to either the heart or lungs  2 atria (right and left) o Thin-walled muscle o Pumps blood to ventricles  2 ventricles (right and left) o Thick-walled muscle o Pumps blood to lungs (right) and body (left) o Great vessels  Bring blood to atria OR take blood away from ventricles  Right side:  Superior and inferior vena cava (to atrium) o Veins; merge and dump blood together in atria)  Pulmonary trunk (from ventricle) o Artery; branches into 2 branches: right and left pulmonary artery  Left side:  Pulmonary veins (to atrium)  Aorta (from ventricle) o Main artery taking blood away from heart to rest of body  Arteries: take blood AWAY from heart  Veins: bring blood BACK to heart  Pulmonary = lungs  AV= atrioventricular (separate atria from ventricles)  Right AV and Left AV  Allow for flow of blood from atria to ventricle o NOT ventricle to atria (in a healthy person)  Semilunar valves- separate ventricles from great vessels  Aortic valve- separates left ventricle form aorta Cardiovascular System Lecture 7 notes  Pulmonary valve- separates right ventricle from pulmonary trunk  They prevent blood from leaking back into ventricles o Blood flow through heart  Atria  Flows from superior and inferior vena cava (from body) TO right atrium  Flows from pulmonary veins (from lungs) TO left atrium  Valves  Right atrium pumps blood through right AV valve TO ventricle  Left atrium pumps blood through left AV valve TO ventricle  Ventricles  Flows from right ventricle TO pulmonary trunk (to lungs)  Flows from left ventricle TO Aorta (to body)  Right structures = oxygen poor  Left structures = oxygen rich  The two sides of the heart work simultaneously  Conduction system of the heart o Cells that initiate and regulate a heart beat o Causes an action potential to initiate in atria, DOWN to the ventricle’s base, then UP the ventricle sides o Includes: sinoatrial node, atrioventricular node, atrioventricular bundle and Purkinje fibers o SA node cells – considered the pacemaker and are located in the right atria  SA node- grouping of conductive cells  Excitation of SA node cells results in excitation (and contraction) of surrounding muscle cells in ATRIA ONLY  Excited 60-100 times per minute (fastest of conductive cells)  Electrical signal can pass to neighboring cells of atria  Electrical signal cannot pass into ventricles because of fibrous skeleton  SA node cells do not have a stable RMP  This is because of cation leak channels Cardiovascular System Lecture 7 notes o Allow sodium to diffuse into cell o More leak channels than pumps  contributes to the fact that there’s not a stable RMP  No stimulus required, because of leak channels  This results in depolarization to threshold W/O neuronal excitation = auto-rhythmic = can contract on its own o AV node = “electrical gateway” into ventricles  AV node cells conduct action potential to additional conductive cells of the ventricles  Fibrous skeleton does not allow signal to travel outside the right atrium, so it goes through AV node  Electrical signal causes contraction  Without SA node action potential, AV node cells are excited 60-80 times per minute (slower than SA node cells) o AV bundle cells conduct action potential to the base of the ventricles  Without SA node or AV node action potential, bundle cells are excited 40-60 times per minute o Purkinje fiber cells conduct action potential to muscle cells of ventricle walls  Without SA node, AV node, or bundle action potential, Purkinje cells are excited 20-40 times per minute  Mechanism of a heartbeat - contraction (summarized) o Cells of the SA node triggers an action potential (do this bc of pacemaker potential; bc they’re leaky, allows cations to leak in) o Action potential moves through the two atria causing contraction  This is also called atria systole (=contraction) (diastole is relaxed) o The action potential depolarizes the cells of the AV node  This is also called ventricular systole (diastole is relaxed) o Action potential propagated down the AV bundle cells o Action potential propagated throughout the ventricles, causing contraction from the bottom up (toward the major vessels, (Great vessels)) o Process starts of again, and again… Cardiovascular System Lecture 7 notes


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