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MaggieForemanCardiovascularSystem (Heart (Conduction System of the Heart…
MaggieForemanCardiovascularSystem
Heart
Pericardial Membranes
Fibrous Pericardium - covers entire outside of heart, made of dense irregular connective tissue, extends from diaphragm to roots of large vessels, keeps heart in place and from heart overfilling.
Serous Pericardium - two layers, parietal and visceral, made of simple squamous epithelium and small amount of areolar connective tissue.
Parietal - outer layer
Visceral - right on the heart
Pericardial Cavity - between layers of serous membrane, filled with serous fluid - slippery and lubricating
Layers of Heart Walls
Endocardium - "inside heart" lines heart and covers valves, simple squamous epithelium and areolar connective tissue
Epicardium - "upon the heart" = visceral pericardium - serous membrane, areolar connective tissue and simple squamous epithelium
Myocardium - "heart muscle" = muscle, spiral shape helps squeeze the blood out (wrings it out)
Microscopic Anatomy of Myocardium
Cardiac Muscle is branched - myofibrals = sarcoplasmic reticulum, T-tublues
Has intercalated discs
Fascia adherens are desmosome-like structures (zipper)
Gap junctions - electrical signals pass from one cell to the next
Heart Valves
Atrioventricular Valves - move blood from atria to ventricles
Right AV Valve/tricuspid
Left AV Valve/bicuspid/Mitral valve
Semilunar Valves - 3 cusps each, forced open
Pulmonary Semilunar Valve
Aortic Semilunar Valve
Conduction System of the Heart
Sinoatrial (SA) Node = "pace maker" - regulates beat speed, located in right atrium (can't see it), unique muscle tissue with ability to generate an electrical signal, makes atria connect (using gap junctions to spread signal)
Atrioventricular (AV) Node - delays signal short time while ventricles fill with blood
AV Bundle - bundle of His
Bundle Branches - in interventricular septum
Purkinje Fibers
Systole (contracting) and Diastole (resting)
Blood Vessels
Veins - carry blood back to heart
Large Veins
Fewer elastic fibers than arteries
Medium-Sized Vein
Valves keep blood moving forward (still quite low blood pressure)
Venule
Smallest of veins, much like capillaries, still some exchange of materials, 1-2 layers of smooth muscle
Capillaries - absent in epithelial tissue, cornea, lens, cartilage
Fenestrated
holes in epithelial cells - more leaky, in locations where high rate of exchange needed ie. small intestine (villi), kidneys, choroid plexus, endocrine glands
Sinusoid
large clefts/pores, patches of missing basement membrane, winding - lots of material exchange (can exchange whole cells and proteins), found in liver, red bone marrow, spleen
Continuous
Most common type, found in CNS, skin, lungs, skeletal muscle, smooth muscle, least leaky type "clefts"
Arteries - carry blood away from heart
Muscular/Distributing Arteries
For size, more muscle than any other artery, distal from heart, moves blood to organs/parts - innervated b/c smooth muscle, can dilate and constrict to move blood where needed (digestion, exercise)
Arterioles
"Little arteries" smallest and most distal, one or two layers of smooth muscle - capable of changing diameter to regulate blood flow (like muscular arteries)
Elastic/Conducting Arteries
Largest of three types, move large amounts of blood (aorta, pulmonary trunk) *proximal to heart - lots of elastic walls (most of three types) , stretch and recoil propels blood forward
Blood
Plasma - blood is 55% plasma
Liquid portion of blood, 90% water, 10% ions, sugar, hormones, vitamins, amino acids, lipids (nutrients), 100+ different molecules
Proteins
Globulin - antibodies (immunoglobins) protect from pathogens, foreign body transporters
Fibrinogen - involved in blood clotting, a protein with fibers (scabs)
Albumin - helps keep water in blood vessels
Cells
Erythrocytes - heavy (iron), hemoglobin binds to oxygen, donut shaped because they lose nucleus and organelles, created in red bone marrow, transport oxygen
Leukocytes - differ in size and color
Neutrophyl - multi-lobed nucleus, light cytoplasm
Eosinaphyl - cytoplasm is red/orange/pink
Basophyl - granulated, can't see nucleus
Lymphocyte - littlest, mostly nucleus, crescent cytoplasm
Monocyte - lighter and bigger (4x's size)
Platelets - smaller pieces between erythrocytes - thrombocytes, role in plugging leaks, stopping bleeding and clot formation