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BIO202 - Chapter 20: Blood Vessels and Circulation

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Arteries
Carry blood away from the heart
Veins
Carry blood back to the heart
Capillaries
Connect smallest arteries to veins
Tunica Interna
Inner lining of arteries, coated with prostacyclin
Tunica Media
Middle, thick layer of arteries; responsible for vasomotion
Vasomotion
Changes in the diameter of the blood vessel brought about by smooth muscle
Tunica Externa
Outermost layer of arteries
Vasa Vasorum
Small vessels that supply blood to at least the outer half of the larger vessels
Conducting Arteries
Largest arteries; Expand during systole, recoil during diastole which lessens fluctuations in blood pressure
Elastic, Large
Other names for Conducting Arteries
Distributing Arteries
Medium arteries; Distribute blood to specific organs
Muscular, Medium
Other names for Distributing Arteries
Resistance Arteries
Small arteries that control amount of blood to various organs
Arterioles
Smallest arteries
Metarterioles
Short vessels that link arterioles to capillaries
Capillaries
Site where nutrients, wastes, and hormones pass between the blood and tissue fluid through the walls of the vessels (exchange vessels)
Continuous Capillaries
Most common capillaries; Tight junctions form a continuous tube with intercellular clefts
Fenestrated Capillaries
Capillaries that are riddled with holes called filtration pores
Sinusoids (Discontinuous Capillaries)
Capillaries with large fenestrations
Thoroughfare Channel
Metarteriole that continues through the capillary bed to the venule
Precapillary Sphincters
Control which capillary beds are well perfused
Capacitance Vessels
Other name for veins
Resistance Vessels
Other name for arteries
Postcapillary Venules
Smallest veins
Large Veins
Veins that feature a thin tunica media with moderate amount of smooth muscle
Heart - Arteries - Arterioles - Capillaries - Venules - Veins
6 Steps of the Simplest & Most Common Circulatory Route (in order)
Portal System
Circulatory route in which blood flows through two consecutive capillary networks before returning to the heart
Anastomoses
Circulatory route where two blood vessels merge
Blood Flow
The amount of blood flowing through an organ, tissue, or blood vessel in a given time
Perfusion
The rate of blood flow per given volume or mass of tissue in a given time
Systolic Pressure
Peak arterial blood pressure
Diastolic Pressure
Minimum arterial blood pressure
120/75
Normal blood pressure
Pulse Pressure
Difference between systolic and diastolic pressure
Mean Arterial Pressure (MAP)
Average of measurements at several intervals throughout the cardiac cycle
Peripheral Resistance
The opposition to flow that blood encounters in vessels away from the heart
Viscosity
Peripheral resistance increases with ____
Blood Flow
Peripheral resistance decreases with ____
Viscosity, Vessel Length, Vessel Radius
3 Things that Affect Peripheral Resistance
Increased
Increased vessel radius produces ___ flow
Capillary Walls
Location of exchanges made between blood and surrounding tissues
Capillary Exchange
Two way movement of fluid across capillary walls
Diffusion, Transcytosis, Filtration, Reabsorption
4 Mechanisms involved in Capillary Exchange
Blood Hydrostatic Pressure
Drives blood out of the capillary
Colloid Osmotic Pressure
Draws fluid into the capillary
Venous Return
The flow of blood back to the heart
Local, Neural, Hormonal
3 Types of Vasomotion Control