CARDIOVASCULAR SYSTEM Flashcards
what does the cardiovascular system consist of?
heart
arteries
capillaries
veins
what is the function of the cardiovascular system?
uptake of nutrients
excretion of waste
homeostasis: fluid/cells leave blood through capillaries + re-enter capillaries via lymphatics
heart acts as a pump
where is the heart located?
Lies between lungs in mediastinum (2nd-6th rib)
what is the surface of the heart made of?
fibrous pericardium - tough CT
what is the function of the fibrous pericardium?
protection, anchors heart to diaphragm & large vessels, prevents overfilling
what is the deep layer of the heart made of?
serous pericardium. 2 layers- parietal, visceral (epicardium) at surface of heart
what is the pericardial cavity?
Serum-filled space in between
what are the 3 layers of the heart wall?
pericardium, myocardium, endocardium
what is the pericardium/ epicardium?
outer layer of fibrous tissue
what is the myocardium?
middle layer of thick muscle, CT, thickest around vessels and prevents over dilation
what is the endocardium?
inner layer of squamous epithelial cells
what are the 4 chambers in the heart?
2 small atria & 2 large ventricles
what is the atria?
Thin-walled
Posterior wall smooth, anterior ridged with pectinate muscles
what 3 veins allow blood to enter the right atrium?
Superior Vena Cava
Inferior Vena Cava
Coronary Sinus
where does the superior vena cava bring blood from?
upper body
where does the inferior vena cava bring blood from?
lower body
where does the coronary sinus bring blood from?
heart myocardium
how does blood enter the left atrium?
4 pulmonary veins, - from the lungs back to heart
what is the ventricle?
thick-walled
Walls - muscle ridges: trabeculae carnae
where does blood go to from the right ventricle?
pulmonary trunk to lungs
where does blood go to from the left ventricle?
aorta to body
what are the 2 blood circuits?
pulmonary circuit
systemic circuit
where is the pulmonary circuit and where does blood travel?
Right, to/from lungs
where is the systemic circuit and where does blood travel?
Left, to/from all body tissues
which circuit is more resistant?
5x more resistance
3x thicker walls of LV v RV
how many heart valves are there?
2 Atrioventricular (AV) 2 Semilunar (SL)
what are the 2 AV valves?
Right: tricuspid Left: bicuspid/mitral
what are the 2 SL valves?
One aortic & one pulmonary
where are no valves found?
between Vena Cava & pulmonary vein and their atria
what is backflow during atrial contraction controlled by?
by compression & collapse of atrial myocardium
what does the coronery circulation involve?
Right/left coronary arteries; base of aorta around heart, capillary beds, cardiac veins, coronary sinus and right atrium
what are the 3 layers in blood vessels?
tunica intima, tunica media, tunica adventitia
what is the tunica intima?
Inner layer: endothelium continuous with endocardium
what is the tunica media?
Mid layer: circularly arranged smooth muscle & sheets of elastin
what are the vasomotor nerves involved in?
vasodilation/vasoconstriction. Maintains BP
what is the tunica adventitia?
Outer layer: loosely woven collagen fibers for protection/anchoring
what do larger vessels contain?
vasa vasorum
what is vasa vasorum?
vessels of vessels
what are the elastic arteries?
Largest, thick-walled, near heart (aorta & major branches)
what do elastic arteries contain?
Elastin in all 3 T’s, esp. T. Media
when are elastic arteries inactive?
in vasoconstriction
what are the muscular arteries?
Muscular or distributing arteries
what does muscular arteries contain?
More smooth muscle, less elastin
when is the muscular artery active?
vasodilation
what are the arterioles?
Smallest, thin T. Media. Single layer of smooth muscle around endothelium
what do arterioles control?
Control blood flow to capillaries
what are the capillaries?
V. thin - T. Intima only. 1 endothelial cell layer, exchange
where aren’t the capillaries found?
ligaments, tendons, cartilage, epithelia, cornea, lens
what are the continuous capillaries?
Most common, esp. skin & muscle
Incomplete tight junctions (not brain) intercellular clefts, fluid & solute exchange
what are fenestrated capillaries?
Similar but membranous pores in some endothelial cells higher fluid & solute permeability. Active abs.
where are fenestrated capillaries found?
Gut, kidney
what are sinusoidal capillaries?
fenestrated with large irregular lumen, fewer tight j’s, larger IC’s, large mol. exchange.
what is the flow in the sinusoidal capillaries like?
slow, immune surveillance
where are the sinusoidal capillaries found?
liver, bone marrow, lymphoid tissues, endocrine organs
what are capillary beds?
c
what vascular shunt?
Connects arteriole & venule at ends of bed
what true capillaries?
Pre-capillary sphincter at metarteriole. Regulates flow via vasomotor nerves
what are venules?
Post-capillary smallest - few fibroblasts. V porous (fluid/wbc exch.)
what are larger venules?
some T. Media & T. Adventitia.
how much blood is held in veins?
65%
what are veins?
Thinner than arteries & larger lumens
T. media: v little smooth muscle or elastin
T. Adv. rel. thick, with longitudinal smooth muscle
what is found in veins?
BP low thinner walls. Valves to prevent backflow.
what are venous valves?
Formed from folds in T. Intima
