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Cardiovascular system (Heart (Heart valves (Tricuspid valve (Closes upper…
Cardiovascular system
Heart
Pericardial membranes
Fibrous pericardium
Covers the heart, it’s a sac, dense irregular CT, tough, keeps the heart in place and keeps it from overfilling with blood
Serous pericardium
Has two parts, both made of simple squamous epithelium and areolar CT.
Parietal pericardium
Not directly on organ
Visceral pericardium
Directly on organ
Pericardial cavity
Filled with serous fluid, reduces friction between the heart and surrounding organs such as the lungs and sternum
Layers of the heart wall
Epicardium
Same as visceral pericardium, serous membrane
Myocardium
Muscle on the heart
Endocardium
Likes the heart and covers the valves, simple squamous epithelial and areolar CT.
Microscopic anatomy of myocardium
Intercalated discs have fascia adherns(desmosone like structures), strongest junctions that hold cells together.
Gap junctions which send electrical signals, movement of ions
Heart valves
Tricuspid valve
Closes upper right chamber that holds blood from coming into the body, opens to allow flow from right atrium to right ventricle
Bicuspid valve
Closes left atrium collecting blood coming in from the lungs, opens to allow blood to flow from the left atrium to left ventricle
Pulmonary valve
Closes right ventricle, opens to allow blood to be pumped through the pulmonary artery where it gets oxygen
Aortic valve
Closes the lower left chamber that holds oxygen rich blood before its pumped out into the body, opens to allow blood to leave the heart from the left ventricle to the aorta and into the body
Conduction of the heart
•SA node known as the “pacemaker” sets your heart rate, generates electrical signals that spread through myocardium of the atria, atria contracts and sends signals to the AV nodes
•AV nodes have a short delay before sending the signals father to allow ventricles to fill, from the AV nodes they go to the AV bundle
•AV bundle-cells collecting signals
• from the AV bundle it travels to the right and left AV branches
•from the AV branches it goes to perkinjie fibers, brings signal to the apex first than ventricles, goes up the sides and squeezes blood upward
Blood vessels
Artery types
Elastic/conducting
Most elastic fibers, moves blood away from the heart, largest proximal to the heart and major branches, stretch and recoil to move blood foward, many layers of smooth muscle
Muscular/distributing
More muscle than other arteries relative to size, ales blood to organs or parts of organs, distal to elastic arteries, constrict or dialate to decrease or increase blood flood, many layers of smooth muscle
Arterioles
1-2 layers of smooth muscle, can constrict or dialate, very small
Capillary types
Continuous
Most common, found in CNS, lungs and skin, smooth and skeletal muscle, have intercellular clefts that make them somewhat leaky
Fenestrated
Means capillaries with windows, found in areas with high rate of exchange such as kidneys, small intestines, choroid plexus, and endocrine glands, more leaky than continuous
Sinusoid
Large type of capillary, winds around, large items can be exchanged such as proteins and whole cells. Red bone marrow, liver makes a lot of proteins, spleen whole cells, leakiest capillary
Vein types
Venules
Smallest type of vein, 1-2 layers of smooth muscle, have all the tunics
Veins
Less elastic than arteries, have valves, gets blood back to the heart
Blood
Plasma
Liquid portion of blood, more than 100 different molecules in plasma, ions, minerals, vitamins, hormone levels, nutrients such as lipids, sugars and amino acids all can be found in the plasma
Cells
Widely spaced, have extracellular matrix called plasma