intro 2 Flashcards
Coronary arteries arise from
root of aorta
right main coronary artery
- supplies left atrium and ventricle
2. bifurcates to left anterior descending and circumflex arteries
widow maker
LAD (left anterior descending artery)
coronary veins
- mostly parallel the coronary arteries
- many veins drain into coronary sinus, a large vein on the posterior side of the heart that empties into the right atrium
- some drain directly to the right atrium
coronary capillaries
very dense–several capillaries associated with each cardiac myocytes
arterial system
- distribution
2. aorta, large artery, small artery, arteriole
microcirculation
- exchange and filtration
2. capillaries
venous system
- collection
2. venule, vein, vena cava
aorta
- large single outflow from left side of heart (~25 mm diameter)
- Elastic & smooth muscle fibers – compliance helps dampen pulsatile flow
Arteries
- Thick walled, to resist expansion
2. Primarily serve to distribute blood to different organs
Arterioles
- Relatively thicker walls, with lots of vascular smooth muscle
- Highly innervated – primary site of regulation of vascular resistance
- “resistance vessels” (small arteries & arterioles)
Capillaries
- Exchange vessels
2. Walls = single cell layer of endothelial cells
Venules, Veins
- Thin walls relative to similar diameter arteries
- “capacitance vessels” – most of blood volume
- Low pressure, with one-way valves
Vena Cavae
- Two branches (superior vena cava & inferior vena cava)
2. Large diameter, but very thin wall (very low pressure)
Tunica adventitia
- outermost layer
2. connective tissue (collagen & elastin)
Tunica media
- middle layer
- Innervated smooth muscle cells
- Controls vessel diameter
Tunica intima
- inner layer
- connective tissue and vascular endothelium
- Important for signaling
- Site of atherosclerotic plaque formation
capillaries are the site of
gas, nutrient and waste exchange
Blood flow through capillary beds determined by
pressure gradients
blood flow through capillary bed is regulated by
arterioles & precapillary sphincters
precapillary sphincters =
smooth muscle bands at junction of arteriole and capillaries
the lymphatic system is a pathway for
fluid and large molecules to move from interstitial space to blood
Lymph is
filtered interstitial fluid (filtered in Lymph Nodes)
lymphatic capillaries are
porous blind end capillaries
Flow in lymphatic system is promoted by:
- increased interstitial pressure
- smooth muscle contraction in lymph vessels
- contraction of surrounding skeletal muscle
Lymphatic system is
low pressure, vessels have one-way valves
Lymph flow ____ per day
~2-4 L
vs. 7000 L blood flow per day
which vessel layer controls vessel diameter?
tunica media
which is the site of atherosclerotic plaque formation?
tunica intima
