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BenkofskeShelby Cardiovascular System (Heart (microscopic anatomy of…
BenkofskeShelby Cardiovascular System
Heart
pericardial membranes: double-walled sac that contains the heart and contains pericardial fluid, protects the heart, keeps in the same location so it does not move
fibrous pericardium: most superficial layer, made up of dense and loose connective tissue, anchors to surrounding walls, protects the heart, thicker layer than the two serous pericardial layers
serous pericardium: contains 2 layers
parietal: fused to the fibrous pericardium, just deep to the fibrous pericardium
visceral: near the epicardium and is sometimes referred to as the epicardium when it is in contact with the heart
pericardial cavity: space between the parietal and visceral layers that contains lubricating serous fluid called pericardial fluid
layers of heart wall
Epicardium: "upon the heart", visceral layer of serous pericardium, and composed of fat
Myocardium: "muscle of heart", composed of cardiac muscle tissue, the bulk of the heart, contracts to circulate blood, oriented in circular bundles
endocardium: "inside the heart", deep to the myocardium, composed of simple squamous epithelium, lines the hearts chambers and covers the heart valves
microscopic anatomy of myocardium
composed of cardiac muscle; involuntary and striated
cardiomyocytes: heart muscle cells that are joined by intercalated disks and encased in collagen, contracting cells, allow heart to pump
contraction is triggered by an action potential from the AV node that spreads to the myocardium
contain; T-tubules, cardiomyocytes, intercalated discs, fibroblasts, and extracellular matrix
heart valves
tricuspid valve: the valve that connects the right atrium and the right ventricle
bicuspid valve: the valve that connects the left atrium and the left ventricle
aortic semilunar valve: the valve that connects the left ventricle and the aorta so that blood can be distributed around the body
pulmonary semilunar valve: the valve that connects the right ventricle and the pulmonary artery so that blood can be distributed to the lungs
conduction system of heart
SA node: "pacemaker" makes the heartbeat on its own, sets heart rate, generates an electrical signal that spreads through the myocardium of the ATRIA (cause atrial contraction), sends electrical signals to the AV node
AV node: allows a short delay to take place so that the ventricles can fill with blood and then contract to push blood through the valves
Route: SA node > AV node >AV bundle > right and left bundle branches > Purkinje fibers
Purkinje fibers: fibers that come off of the bundle branches and are located near the apex in the myocardium, cause contraction of the ventricles to push the blood out
Blood Vessels
artery types
have a tunica externa that is thinner than veins, contains collagen and elastic fibers and are protective and strong. the tunica media has smooth muscle, and the tunica intima has an internal elastic membrane and endothelium (simple squamous epithelium)
elastic /conducting arteries: most proximal to heart, move blood away from heart, largest, strength and recoil, propel blood forward
aorta and major branches
muscular/distributing arteries: more muscle relative to size compared to other arteries, take blood to organs or parts of organs, distal to elastic/conducting arteries, constrict or dilate to increase/decrease blood flow
renal artery, hepatic artery
arterioles: very small, tunica media is only 1-2 layers of smooth muscle, can constrict or dilate, leads to capillaries
capillary types
do not have a tunica externa or a tunica media, only have a tunica intima that is an endothelium layer with a basement membrane
continuous: most common, somewhat leaky, between the epithelial cells of the capillaries
lungs, skin, smooth/skeletal muscle
fenestrated: "window"=pores, little holes throughout, found in places where high rate of exchange is necessary
small intestine, kidney, choroid plexus, endocrine glands
sinusoid: large, winding, very leaky, allow large items to be exchanged (proteins/whole cells)
red bone marrow, liver, spleen
capillary bed: come from arterioles, many routes, exchange nutrients on way
everywhere (except avascular tissue)
vein types
contain a tunica externa that is thicker than arteries and made of collagen fibers and fewer elastic fibers than arteries, a tunica media with smooth muscle, and a tunica intima with only endothelium
large vein: get blood back to the heart, largest type
medium vein: contains valves to keep blood moving in one direction
venules: smallest vein type, similar to capillaries, has some exchange, very little smooth muscle but all layers are present
Blood
plasma: extracellular matrix of blood, 90% water, liquid, greater than 100 molecules dissolved in plasma
contains minerals, ions, nutrients (lipids, sugars, amino acids), vitamins, and hormones
cells: not close together and characterized as connective tissue
erythrocytes: red blood cells, created in the red bone marrow, lose their organelles (nucleus), have a biconcave shape to increase surface area, contain hemoglobin
Thrombocytes: not cells, prices of cytoplasm from megakarocyte, and involved in clotting blood
Leukocytes: white blood cells involved in immunity, fight off pathogens/bacteria/viruses
agranulocyte
monocyte
lymphocyte
granulocyte
basophil
neutrophil
eosinophil
Proteins
albumin:
globulins:
fibrinogen: