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- >hollow, cone fist size, cone shaped organ
- >enclosed within the mediastinum
- >rests on diaphragm at the 5th intercostal space
- >encased in a double walled sac called pericardium
- >4 hollow chamber
- >2 artia and 2 ventricles
- >act as a double pump
- >divided by interventricular septum
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Pericardium
- > double walled sac surround the heart
- >2 layers > Fibrous & serous
- >Serous pericardium consists of 2 layers>Parietal & visceral layer
- >Visceral layer is part of the wall of heart called epicardium
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Muscle layers of the heart
Endocardium - Inner layer
>lines each 4 chambers of heart to ensure blood flows freely through the heart
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muscle layer
Myocardium - middle layer
- >consists of thick cardiac muscle that contract
- >responsible for the majority of the work that occurs in the heart.
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Muscle layer
Epicardium - outer layer
>also visceral layer of pericardium>Produce serous fluid to ensure the heart beats without any friction or resistance>without fluid, friction will occurs>loss of serous fluid results in inflammation of percardium causing pericarditis.
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Atria
>receiving chambers where blood flows passively into them
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Ventricles
- >discharging chambers that force blood out of the heart into the circulation during contraction
- >left ventricle has the thickest walls because it has to pump the blood throughout the entire body and back to the heart.
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Valves
- >ensure blood flow in one direction
- >4 valve to prevent backflow of blood into the heart chambers
- >attached to valve are flaps
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Av valve
- >located between atrial and ventricular chambers
- include
- >bicupsid (mitral)(L atria)
- >Tricupsid (R atria)
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Semi Lunar valves
>located in chambers of ventricles
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Pulmonary circulation (right side)
- >deoxygenated blood rushes into R atrium via superior/interior vena cavae
- >heart pumps blood into R ventricl via pulmonary trunk
- >blood leaves the heart through the R ventricle vai pulmonary trunk
- >Pulmonary trunk divides nto L & R pumonary arteries
- >Blood travel through arteries to capillaries at the lungs to collect O2 and dispose of CO2
- >Oxygenated blood returns to the heart via pulmonary veins
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Systemic circulation ( left side)
Function is to provide the body with needed oxygen and nutrients.
L ventricle is musch more powerful than R ventricl becuase it has to travle from the body's tissues over a long distance.
- >blood returns to L side of the heart rich in O2/nutrients and low in CO2 via pulmonary veins
- >blood enters the heart in L atrium into L ventricles
- >oxygenated blood leaves the heart via L ventricle and enters the aorta
- >Aorta branches into systemic arteries into capillaries
- >O2 diffuses from capillaries into capillary beds in body's tissues.
- > at the same time CO2 diffuses from tissues's capillary beds into the blood
- >deoxygenated blood enters the R side of the heart via vena cavae
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Conduction of heart
- >cardiac muscle initiates own contraction to ensure heart functions as a whole
- >diferent cells maintain different rhythms
- >Atria cell 60 x min
- >Ventricular cell 20 - 40 x min
- >nervous system aid in maintaining some form of unity
- >autosome NS
- >intrin conduction system
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Autonomic nervous system
>acts to decrease or increase heart rate
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Intrinsic conduction system
- >found in heat tissue
- >responsible for the rate of contraction and for setting rhythm via electrical current taht constitues a pulse
- >consists of SA node (most important), Av node (pacemaker), Atrioventricular bundle, bundle branches, Purkinje fibres
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cardia/Coronary circulation ( serves the heart)
- >heart needs 5% of output ot supply to self.
- >C.C deliever O2 rich blood into myocardium for processing
- >As heart relaxs, oxygenated blood leave L ventricle via the aorta
- >blood enters R & L coronary arteries located at the base of the aorta
- >blood enters anterior and posterior brances
- >oxygen is delieverd to mayocardium
- >deoxygenated blood returns to the heart via caridac veins into coronary sinus and empites into R atrium.
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Vascular system: the vessels
- >Blood leaves the heart and force into arteries then arterioles as the heart beats
- >blood moves into capillary beds found within tissues
- >movement of nutrients, O2, CO2 occurs within capillaries via diffusion
- >blood move from capillaries into venule then larger veins
- >once in vein blood rushes back into the heart.
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Arteries (single - arteriole)
- Drain oxgenated blood away from the heart
- >3 layers (tunica or lumen)
- >closer to heart
- >Thicker walls due to tunia media is heavier
- >Capable of expansion and recoil to normal size
- >Strong stretchy walls
- >high pressure
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Veins (single. Venule)
- Return deoxygenated blood to the heart
- >3 layers (tunica or lumen)
- >further from heart
- >Thinner walls especially in tunia media
- >low pressure
- >capable of returning equal amount of blood back to heart
- >valve work to return blood back to heart
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Capillaries
- >branch thru tissues, connecting the arterioles to the venules
- >only vessel that move between tissues by weaving and winding causing exchange of gases & nutrients between blood and tissue
- > 1 thin layer
- >thinness allows diffusion of nutrients between capillaries and tissue to occurs
- >Form capillary beds
- >sphincters that allow blood to bypass tissue cells
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Layers of vein and artery
Tunica intima
- >inner layer
- > lines the interior wall to reduce friction as blood flows thru the vessel
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Tunica Media
- >middle layer of smooth muscle and elastin
- >allows vessels to constrict/dilate
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Tunia externa
- >outer layer
- >consists of collagen that support and protect the vessels
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