Cardiovascular System - midterm 2 Flashcards
Heart
- in a cavity called the mediastinum (= spaces between lungs within thoracic cavity)
Coverings = Pericardium
- double-walled sac surrounding heart
- 3 layers
- between pericardial layers = pericardial cavity with serous fluid (lubricates)
Pericardium 3 layers:
a) fibrous pericardium
- outermost layer = dense irregular CT
- anchors to surrounding structures e.g. diaphragm, great vessels (aorta, vena cava, etc)
b) serous pericardium - 2 parts:
i. parietal pericardium (fibrous pericardium and partietal pericardium = pericardial sac)
ii. visceral pericardium (= epicardium)
- fused to heart surface, so is part of heart wall
Heart wall (3 parts)
a) epicardium
- stratified squamous epithelium and CT
b) myocardium
- = cardiac muscle
- arranged in spiral/circular pattern, reinforced with CT
c) endocardium
- simple squamous epithelium and CT
- epithelium named endothelium - lines inner surface of heart and ALL blood vessels
Chambers and associated blood vessels
a) Right Atrium
- inferior and superior vena cava
- coronary sinus (posterior)
b) Left Atrium
- 4 pulmonary veins
c) Right Ventricle
- pulmonary trunk - divides to form 2 pulmonary arteries
d) Left Ventricle
- aorta
Septa (separate chambers)
a) interatrial septum
- separates atria
b) interventricular septum
- separates ventricles
- deep to inter ventricular sulcus (external)
Fibrous skeleton
- CT fibres around the muscle fibres + CT rings between atria & ventricles at the coronary sulcus
- allows openings to remain open at all times (valves open + close)
- provides electrical insulation - prevents simultaneous contraction of chambers
Atrioventricular (AV) valves
i. bicuspid (mitral) valve
- left side - 2 cusps
ii. tricuspid valve
- right side - 3 cusps
- Chordae tendineae (CT) attach AV valve cusps to papillary muscles (projections of myocardium) - prevent eversion of cusps
Semilunar valves
3 cusps each
i. aortic - separates left ventricle + aorta
ii. pulmonary - separates right ventricle + pulmonary trunk
Cardiac Muscle Cells
- form BOTH contractile myocardium + conduction system
- similarities to skeletal muscle:
a) striated (myofibrils with sarcomeres)
b) has sarcoplasmic reticulum & T-tubules - differences:
a) branched (myofibrils with sarcomeres)
b) uninucleated
c) intercalated discs = region where 2 fibres meet - contain anchoring and gap junctions
Conduction System
- cardiac muscle cells modified to produce and conduct electrical impulses - DO NOT CONTRACT
- have 5 parts
- note: electrical signal spreads from conduction system to contractile cardiac cells when they contract
Conduction system parts:
a) sinoatrial (SA) node
- in right atrium at base of superior vena cava
- generates impulses the fastest - sets pace
b) atrioventricular (AV) node
- base of right atrium
c) Bundle of His
- superior part of interventricular septum
- electrically connects atria to ventricles
d) Bundle of His Branches
- go to each ventricle
e) Purkinje fibers
- terminal fibers in ventricles only
Circulatory Routes
closed, double circulation
- closed = blood confined to heart + blood vessels
- double = 2 routes (pulmonary + systemic)
Adult Circulation: Pulmonary circulation-
- right ventricle to lungs via pulmonary arteries (deoxy blood)
- pick up oxygen in lungs via capillaries
- lungs to left atria via pulmonary veins (oxygenated blood)
Adult Circulation: Systemic Circulation-
- left ventricle to organs via aorta (oxygenated)
- organs remove oxygen via capillaries
- organs to right atrium = systemic circulation > subdivisions/subroutes: - cerebral = brain
hepatic = liver
coronary = heart
