The Heart Flashcards
What the heart does
- Arteries
- Veins
- Great Veins
-Heart propels blood to and from most body tissues via arteries and veins
Arteries: Blood vessels that carry blood away from the heart
Veins: Blood vessels that carry blood back to the heart
Great Vessels: arteries and veins entering and leaving the heart (have a relatively large diameter)
General characteristics & Functions of the Heart (3)
-defn. of blood pressure
- Blood flow is unidirectional
- Acts like 2 side-by-side pumps (work at same rate and pump same volume of blood)
- Develops blood pressure through alternate cycles of wall contraction & relaxation
Blood pressure=force of the blood pushing against the inside walls of blood vessels
-minimum blood pressure essential to circulate blood throughout body
Pulmonary vs Systemic circulation
Pulmonary: Conveys deoxygenated blood from right side of heart to lungs to be oxygenated (and to release CO2)
Systemic: Moves oxygenated blood from left side of heart to systemic cells of rest of body
-deoxygenated blood return to right side
Basic flow of blood (heart, lungs, body)
Right side of heart -> lungs -> left side of heart -> systemic tissues of body -> back to right side of heart
Position of the heart
- base
- apex
- Slightly left of midline, deep to the sternum in the mediastinum (compartment of the thorax)
- Base of heart= posterosuperior surface of heart - is mainly left atrium
- superior border is formed by the great arterial vessels & superior vena cava
- Apex: inferior conical end
- inferior border formed by right ventricle
Pericardium
- Composition
- Function
- 2 Parts
-is a tough sac that the heart is enclosed in
-Restricts heart’s movement and prevents it from overfilling w/ blood
2 parts:
1. Firbrous pericardium: outer covering of tough, dense CT
-attached to diaphragm and base of great vessels
2. Serous pericardium: inner portion = thin, double-layered serous membrane subdivided into;
i) Parietal layer (lines surace of fibrous pericardium)
ii) Visceral layer (aka Epicardium - covers outer surface of heart)
-b/w 2 layers = pericardial cavity where serous fluid secreted to lubricate movement of heart
Anatomy of Heart Wall
- 3 layers;
1. Epicardium: outermost layer - also known as visceral layer- serious membrane & areolar CT
- as we age more fat is deposited - becomes thicker and more fatty
- Myocardium: Middle layer
- composed of cardiac muscle tissue (is thickest layer)- is where heart attacks occur
- Endocardium: internal surface of heart & external surfaces of heart valves
- Myocardium: Middle layer
- simple squamous epithelium & layer of aerolar CT
External Heart Anatomy
- Chambers
- Auricle
- 4 hollow chambers; 2 small atria & 2 larger ventricles
- anteroinferior borders of atria = muscular extension called AURICLE
- Coronary Sulcus: deep groove that separates the atria and ventricles
Atria (general facts)
- Thin walled chambers located supriorly
- receives blood returning from both circulations & passes to ventricle on each side
Ventricle (general facts)
- inferior chambers
- 2 large arteries (pulmonary artery & aorta) leave at superior pole
4 Valves in the heart
- Right atrioventricular (tricupsid)
- Pulmonary semilunar
- Left atrioventricular (bicupsid or mitral)
- Aortic semilunar
Right atrium
- what it receives
- 3 veins that drain into it
- associated valve
- Receives venous (deoxygenated) blood from heart, muscles & systemic circulation
- 3 veins drain into it;
- Superior vena cava
- Inferior vena cava
- Coronary sinus
- Right atrioventricular valve separates right atrium from right ventricle
- forced closed when right ventricle begins to contract - prevents blood backflow
Right Ventricle
- What it receives
- Features
- Receives deoxygenated blood from right ventricle (through right atrioventricular valve)
- Intraventricular septum forms thick wall between right and left ventricles
- Has large, irregular muscular ridges on inner wall = trabeculae carneae
- typically 3 cone-shaped muscle projections = papillary muscles
- anchor thin strands of CT w/ collagen fibres called chordae tendineae (attach to tricuspid valve)
- superior end (or roof) = conus arteriosus (smooth area)
- beyond this = pulmonary semilunar valve (marks end of ventricle & beginning of pulmonary trunk)
Left Atrium
- what it receives
- how separated from left ventricle
- Oxygenated blood from lungs travels through pulmonary veins to left atrium
- separated from left ventricle by left atrioventricular valve (tricuspid)
- forced shut when left ventricle contracts in similar fashion to closing of right antrioventricular valve
Left Ventricle
- Wall typically 3 x thicker than right
- superior end (roof) = aortic semilunar valve
- marks end of ventricle and beginning of aorta
- pressure of blood backflowing onto valve is what closes them