Heart and blood vessels Flashcards
-List and describe layers of heart wall -Describe structure of pericardium -Describe structural features of valves -Describe impulse conducting system of the heart -List and describe layers of the walls of blood vessels -Compare and contrast structure of arteries and veins (33 cards)
Describe general organisation of the heart
The heart is divided into two sides, each with an atrium and ventricle separated by a valve.
Right side- pulmonary circulation. DEOXYGENATED
-fed by inferior and superior vena cavae
-blood is sent to lungs via pulmonary trunk
Left side- Systemic circulation
OXYGENATED
-fed by pulmonary veins
-blood sent to body via the aorta
What is the pericardium?
A fibrous sac that surrounds the heart.
Prevents heart from overexpanding and limits heart motion
Where is the pericardium attached to?
Attached to great vessels at the base of the heart and to central tendon of diaphragm
Describe the two layers that enclose the pericardial cavity
Known and serous pericardium.
Parietal pericardium- lines internal surface of fibrous pericardium
Visceral pericardium- lines the heart and is part of the epicardium. has adipose tissue
The gap between Parietal and Visceral is known as pericardial cavity and contains secretions of pericardial fluid which reduces friction between pericardial membranes
What are the three layers of the heart wall?
Epicardium:
-Made up of simple squamous mesothelium
-Loose connective tissue and adipose tissue containing coronary vessels and nerves that supply the heart called SUBEPICARDIUM.
Myocardium (middle layer):
-thickest layer
-bundles and layers of cardiac muscle cells (intercalated discs)
Endocardium (innermost):
-Smooth inner lining of endothelial cells
-Subendocardium-> loose connective tissue containing small blood vessels and branches of the conducting system of the heart
What are valves composed of? What is their purpose?
-Ensure one-way blood flow
-Composed of fibroelastic connective tissue covered with endocardium
Describe structure of atrioventricular valves.
Right atrioventricular valve has 3 cusps (tricuspid)
Left AV has 2 cusps (mitral/bicuspid)
Cords called Chordae tendineae connected AV valves to papillary muscles on ventricular floor.
What are the semilunar valves?
Valves that control the flow of blood into great arteries
Pulmonary semilunar valve- from right ventricle into pulmonary trunk
Aortic semilunar valve- from left ventricle into aorta
Where is the sinoatrial node?
Located in the wall of superior vena cava and right atrium, deep into epicardium
What is the sinoatrial node?
Specialised cardiac muscle fibers with lots of CT between fibers
Has its own blood supplu
Causes atrial contraction
Where is the atrioventricular node? What does it do?
Located in septum between atria
Begins ventricular contraction
What is the atrioventricular bundle? Where is it?
AKA Bundle of His
Bundle of fibers that enter interventricular septum and divides into 2 branches of Purkinje fibers
Where are Purkinje fibers?
In dense connective tissue of endocardium
What are Purkinje fibers?
Specialised cardiac muscle fibers that cause a wave of ventricular contraction.
supply papillary muscles first then apex of heart
Name the layers of a vessel wall.
Tunica Intima (interna)
-Endothelium and CT (subendothelium)
Tunica Media
-Smooth muscle, collagen and elastic fibers (relative amounts)
Tunica Adventitia (externa)
-Loose connective tissue (relative amounts)
-Can have blood vessels and nerves
for larger vessels
What do arteries do?
Carry oxygenated blood (except pulmonary artery)
Take blood away from heart
Describe appearance of artery
Thick wall compared to lumen diameter
No valves
What are the two types of arteries
Elastic arteries- conducting vessels
Muscular arteries- distributing vessels
Describe structure of Elastic arteries.
Tunica Intima:
-Endothelium
-Underlying CT
Tunica Media:
-Thickest layer with sheets (laminae) of elastic tissue
-Interspersed with smooth muscle and collagen.
Tunica Adventitia:
-Loose CT with lots of collagen to prevent overextension
-Has blood vessels called vasa vasorum
-Has nerves called nervi vasorum
Describe structure of muscular arteries.
Tunica intima:
-Endothelium
-Underlying CT
Tunica media:
-Smooth muscle predominates
-Elastic fibers only;
Internal elastic lamina between intima and media
External Elastic Lamina between media and adventitia.
Tunica Adventitia:
-Loose CT
-Vasa vasorum and nervi vasorum
What is the structure of arterioles?
Tunica media of arterioles is reduced to 2-3 layers of smooth muscle.
Tunica adventitia blends in with surrounding connective tissue
What do veins carry?
Carry deoxygenated blood (except for pulmonary veins)
Take blood to heart
Describe general appearance of veins
-Walls are thin compared to lumen diameter
-Tunica media are thin compared to arteries
-Tunica adventitia large compared to arteries
-Have valves
Describe structure of a large vein, eg. Venae Cavae
Tunica Intima:
-Endothelium
-Underlying CT
Tunica Media:
-Some smooth muscle
-Collagen fibers and little elastic tissue
Tunica adventitia:
-Thickest layer with lots of smooth muscle and collagen
-Extensive vasa and nervi vasorum
