karan arora ix-b
TRANSCRIPT
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The Circulatory System
The function of a circulatory system is to carryblood or hemolymph into close contact with everycell in the body.The most sophisticated circulatory systems
consist of:one or more pumps called heartsarteries (tough, thick-walled tubes) that carryblood away from the heart under high pressure;small vessels called capillaries whose walls arejust one cell thick, allows the exchange of gasesand other molecules with tissues in networkscalled capillary beds; andvessels called veins that return blood to the
heart under low pressure
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Functions of the Circulatory System
Transport oxygen to cells Transport nutrients from
the digestive system to bodycells
Transport hormones to bodycells
Transport waste from bodycells to excretory organs
Distribute body heat
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How Are Oxygen and Carbon
Dioxide Transported in Blood?
Blood : connective tissue that consists ofcells in a watery extracellular matrixcalled plasmaRemainder of the blood is made up offormed elements: platelets, red blood cells,and several types of white blood cells:Platelets : Cell fragments thatminimize blood loss from ruptured blood
vessels by releasing material that assistsin the formation of clotsWhite blood cells: which are part of theimmune system fight infections
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RBCs
Red blood cells (RBCs):transport oxygen from the lungsto tissues throughout the bodycritical role in transporting
carbon dioxide from tissues tolungsIn humans, red blood cellsmake up 99.9% of the formedelements.
contain an oxygen-carryingmolecule called hemoglobin
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Circulation
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How Does the Heart Work?
In animals with closed circulatorysystems, the heart contains at least twochambers.
the atrium receives blood returning from
circulationthe ventricle generates force to propel theblood through the system.
Atria are separated from ventricles byatrioventricular valves.
The number of distinct heart chambershas increased as vertebrates diversified.
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How Does the Heart Work?
Vertebrates evolved two separate pumpingcircuits:
The pulmonary circulation is a lower-pressure circuit to the lungs.The systemic circulation is a higher-pressure circuit to the rest of the body.
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Components of the Human
Circulatory System
TheHeart
Blood Vessels
BloodLymphatic Vessels
Lymph
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Types of Blood Vessels
Capillaries:smallest vesselsthe site where gases, nutrients,and wastes are exchanged betweenthe blood and other tissues
The smallest veins are venules;carry blood back to the heart afterit passes through the capillariesveins have much thinner wallsand much larger interiordiameters than arteries
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Location ofHeart
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Pericardial Cavity
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Layers of Cardiac Tissue
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Visceral pericardium Outer protective layer composed of a serousmembrane
Includes blood capillaries, lymph capillaries,and nerve fibers.
Myocardium Relatively thick. Consists largely of cardiac muscle tissue
responsible for forcing blood out of the heartchambers.
Muscle fibers are arranged in planes,separated by connective tissues that arerichly supplied with blood capillaries, andnerve fibers.
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Heart Anatomy
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TheHumanHeart
The human circulatory system returns oxygen-depleted blood from the body to the right atriumof the heart through two large veins
the inferior and superior venae cavae.When the right atrium contracts:
deoxygenated blood is sent to the rightventricleit contracts and sends blood out to the lungsvia the pulmonary artery
One-way valves ensure that blood follows only
this path. After blood has circulated through thecapillary beds in the lungs alveoli:it becomes oxygenated
returns to the heart through the pulmonaryveins
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The Human Heart
TheHumanHeart
The oxygenated blood enters the leftatrium:
it contracts and pushes the bloodinto the left ventricle
The contraction of the left ventriclesends oxygenated blood at highpressure out the aorta and into:
the arteriescapillariesveins
forms the systemic circulation
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Heart Anatomy
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Heart Anatomy
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Valves
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bicuspid valve
aortic semi lunar
valve
tricuspid valve
pulmonary semi
lunar valve
Heart ValvesHeart Valves
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The Cardiac Cycle
The contraction phase of the atriaand the ventricles:
called systoleis coordinated with their
relaxation phasecalled diastole
A cardiac cycle:consists of one complete
systole and one completediastole
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Contraction cycle of the heart
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Contraction Cycle of the Heart
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Excitation of the Heart
Depolarization of the atria
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Excitation of the Heart
Depolarization of the ventricles
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Excitation of the Heart
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Excitation of the Heart
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Circulatory System -Gross and Cool Facts!
The body of an adult containsover 60,000 miles of blood vessels!An adult's heart pumps nearly4000 gallons of blood each day!Your heart beats some 30 million
times a year!The average three-year-old hastwo pints of blood in their body;the average adult at least fivetimes more!A "heartbeat" is really the soundof the valves in the heart closingas they push blood through itschambers.
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