Blood Vessels Flashcards
Circulatory system includes…
Lymphatic & cardiovascular systems
Cardiovascular system includes….
Heart
Arteries
Capillaries
Veins
Heart
Propels blood through system
Arteries
Vessels from heart carrying oxygenated blood to tissues (away from heart)
Capillaries
Smallest vessels, sites of O2, CO2, nutrient & waste exchange
Veins
Carry deoxygenated blood back to heart
2 major divisions of cardiovascular system
Pulmonary circulation
Systemic circulation
Pulmonary circulation
Conveys blood from heart to lungs and from lungs back to heart
Systemic circulation
Conveys blood from heart to other tissues of the body, and from those tissues back to heart
Lymphatic vascular system
Carries lymph (interstitial fluid) through vessels that connect back to the vascular system and empty into large veins near the heart
Acts as major distributor of immune components (lymphocytes, antibodies)
3 major layers of heart chambers
- Endocardium
- Endothelium
- Myoelastic layer
- Subendocardial layer - Myocardium
- Epicardium
Endocardium
Most internal layer of heart
Subendocardial layer of heart contains ____
Purkinje fibers
Purkinje fibers
Terminal branches of conducting system originating from AV node, deliver contraction impulse to cardiac muscle cells of ventricles
Myocardium
Thickest layer containing cardiac muscle
Epicardium
Simple squamous mesothelium supported by CT
corresponds to visceral layer of pericardium
Layers of vascular wall
Tunica intima
Tunica media
Tunica adventitia
3 components of tunica intima
- endothelium
- basal lamina
- subendothelial layer
Internal elastic lamina
Sheet-like layer of elastin with fenestrations to allow for diffusion of substances deeper into vessel wall
(In subendothelial layer of arteries & arterioles)
What is the thickest layer in arteries & arterioles?
Tunica media
In larger arteries, an ____ separates the tunica media from tunica adventitia
External elastic lamina
What is the thickest layer in veins & venules?
Tunica adventitia
In the tunica adventitia, arteries and veins contain ____ & ____
Vasa vasorum and nervi vasorum
Vasa vasorum
Smaller BVs, supply blood to vascular wall
Nervi vasorum
Autonomic nerves that control contraction of smooth muscle in vessel walls
Blood vessels ____ frequently and undergo _____ into different types of vessels that make up the vasculature
Branch
Gradual transitions
Primary function of large arteries or elastic arteries
Conducting arteries (carry blood to smaller arteries)
Primary function of medium/muscular arteries
Distributing arteries (carry blood to organs)
Capillaries are often surrounded by ____
Pericytes
Pericytes
Perivascular contractile cells that facilitate blood flow; involved in microvascular remodelling & repair
3 histologic types of capillaries
Continuous
Fenestrated
Discontinuous
Most common histologic type of capillary
Continuous
Continuous capillaries
Tight junctions between endothelial cells so that all exchange must occur through the cells
Fenestrated capillaries
- Have small pores called fenestrations through the cells, but basement membrane is continuous
- allows more extensive molecular exchange across endothelium
Discontinuous capillaries (sinusoids, Sinusoidal)
Fenestrations through endothelial cells, larger gaps between cells with discontinuous basement membranes allow for maximal exchange of macromolecules & cells
Post capillary venules collect blood from
Capillary networks
Post capillary venules contain ____
Pericytes
Tunica media of post capillary venules
Establish a tunica media of 2-3 layers of scattered smooth muscle
Important feature of medium veins
Valves
Valves
Thin, paired folds of tunica intima projecting across lumen, help keep venous return directed to heart
Adventitia of large veins
Very thick and contains longitudinal bundles of smooth muscle
Primary Function of lymphatic vessels (lymphatic capillaries)
Remove substances & fluids from Extracellular spaces of CT = lymph
Conveys lymph fluids from tissues into blood
