Cardiovascular System (Heart (Heart Valves (LUBB DUBB: The CLOSING of…
FIBROUS PERICARDIUM: Dense irregular C.T. Keeps the heart in place. Reaches from diaphragm to the roots of the large vessels. Prevents heart from overfilling
SEROUS PERICARDIUM (2 LAYERS): Simple squamous epithelium and areolar C.T. Serous membrane! 1) Parietal Pericardium: Most superficial, around heart. 2) Visceral Pericardium: Located directly on heart. Same as epicardium.
PERICARDIAL CAVITY: Located between visceral and parietal pericardial membranes. Filled with serious fluid, made my serous membranes, to reduce friction.
Layers of Heart Wall
EPICARDIUM: Same as visceral pericardial layer of serous pericardium. Simple squamous epithelium and areolar C.T. Is a serious membrane.
MYOCARDIUM: Muscle layer. Contracts to move blood.
ENDOCARDIUM: Simple squamous epithelium and areolar C.T. Lines inside of heart and covers its valves.
Microscopic Anatomy of Myocardium
INTERCALATED DISCS: Unique to cardiac muscle. Connect to muscle fibers and help to synchronize heart contractions.
FASCIA ADHERENS: Cell junction. Desmosome-like structure (strongest). Located in intercalated discs between muscle cells.
GAP JUNCTIONS: Located on intercalated discs. Act as passageways for electrical signals, particularly movement of ions.
LUBB DUBB: The CLOSING of heart valves. Lubb--atrioventricular valves snapping shut. Dubb-- semilunar valves snapping shut.
TRICUSPID / RIGHT ATRIOVENTRICULAR VALVE: Located between right atrium and ventricle. Low-oxygen blood passes through.
BICUSPID / MITRAL / LEFT ATRIOVENTRICULAR VALVE: Located between left atrium and ventricle. Oxygenated blood passes through.
PULMONARY SEMILUNAR VALVE: Located between pulmonary trunk and right ventricle. Low-oxygen blood passes through here to the lungs.
AORTIC SEMILUNAR VALVE: Located between ascending aorta and left ventricle. Oxygenated blood passes through here to the rest of the body.
Conduction System of Heart
SINO-ATRIAL NODE: Pacemaker. Beats w/o help of nervous system. Located in right atrium. Sets heart rate. Electrical signal passes through myocardium of both atria via gap junctions. After atria contract, signal is sent to AV node.
ATRIVENTRICULAR NODE: When signal arrives here, there's a short delay to allow ventricles to fill with blood. Signal moves to AV Bundle.
AV BUNDLE: Branches off AV node. Signal travels from here to right and left bundle branches.
RIGHT & LEFT BUNDLE BRANCHES: Where AV bundle splits into two, in the inter-ventricular septum. Then "wraps" around ventricles, and stimulates contraction.
PERKINJE FIBERS: Small branches off R & L bundle branches. Last to receive electrical signal.
ELASTIC (CONDUCTING) ARTERY: Most proximal to heart. Move blood directly away from heart. Function: Stretch and recoil, propels blood forward. Examples: Aorta, Brachiocephalic trunk, L common carotid, L Subclavian.
MUSCULAR (DISTRIBUTING) ARTERY: More muscle relative to size compared to other arteries. Takes blood to organs and their parts. Distal to elastic arteries. Constrict and dilate to regulate blood flow. Examples: Hepatic artery, Renal artery.
ARTERIOLES: 1-2 layers of smooth muscle. Can constrict/dilate.
CONTINUOUS CAPILLARIES: Most common!! Somewhat leaky due to intercellular clefts. Found in CNS, lungs, skin, smooth and skeletal muscle.
FENESTRATED CAPILLARIES: Has pores which allow for high rate of exchange. Found in small intestine, kidneys, choroid plexus, endocrine glands.
SINUSOIDS: Large and winding. Allow for exchange of large items, such as whole cells and proteins. Found in red marrow, spleen (whole cells), and liver (proteins).
LARGE VEINS: Example: superior/inferior vena cava.
MEDIUM VEINS: Have valves.
VENULES: Smallest. Capillary-like. Only 1-2 layers of smooth muscle.
ALBUMIN: Helps keep water in blood.
GLOBULINS: Antibodies. Transporters for hydrophobic substances.
FIBRINOGEN: Involved in clotting.
PLASMA COMPOSITION: Liquid extracellular matrix. 90% water. Over 100 different molecules, various ions, minerals, vitamins, lipids, hormones, sugars, and amino acids.
RED BLOOD CELLS: Erythrocytes. Lose many organelles including nucleus. Biconcave in shape to increase surface area, which aids in exchange of oxygen.
LEUKOCYTES: Many. Neutrophils, eosinophils, basophils, monocytes, lymphocytes. Roll in immunity.
THROMOCYTES: Platelets. NOT cells. Pieces of cytoplasm from megakaryocytes. Clots blood.