Chapter 21 - Blood Vessels and Circulation Flashcards
What do arteries do?
Carry blood away from the heart
What are arterioles?
Smallest branches of the arteries that lead to capillary beds
What is the function of capillaries?
Location of exchange between blood and interstitial fluid
What are venules?
Smaller branches of veins that collect blood from capillaries
What is the primary role of veins?
Return blood to the heart
What is the tunica intima?
Inner layer of a blood vessel that includes an endothelial lining
What does the tunica media contain?
Concentric sheets of smooth muscle
What is the tunica externa?
Outer layer of a blood vessel that contains connective tissue
How do arteries differ from veins in terms of wall thickness?
Arteries have thicker walls with more smooth muscle and elastic fibers
What is a key difference between arteries and veins regarding shape when cut?
Arteries stay circular while veins collapse
True or False: Veins have valves to prevent backflow.
True
What are elastic arteries?
Largest arteries, closest to the heart, that can stretch and recoil
What is elastic rebound?
Walls stretch with increasing pressure during systole and recoil during diastole
What are muscular arteries?
Medium-sized arteries with lots of smooth muscle
What are arterioles also known as?
Resistance vessels
Fill in the blank: Vasoconstriction is the _______ of arterial smooth muscle.
Contraction
Fill in the blank: Vasodilation is the _______ of arterial smooth muscle.
Relaxation
What do continuous capillaries have?
Complete endothelial lining
What are fenestrated capillaries characterized by?
Pores in the endothelial lining
What are sinusoids?
Gaps between adjacent endothelial cells
What do venules collect?
Blood from capillaries
What is a key feature of medium-sized veins?
Have three tunic layers
What is the function of venous valves?
Prevent blood from flowing backward
What are capacitance vessels?
Veins that are distensible and act as blood reservoirs
What determines blood flow (F)?
Pressure (P) and resistance (R)
What is the pressure gradient (∆P)?
Pressure difference from one vessel end to the other
What is Poiseuille’s Law used for?
To calculate blood flow (Q)
What does total peripheral resistance refer to?
The resistance of the entire cardiovascular system
What causes vascular resistance?
Friction between blood and vessel walls
What is blood viscosity?
Resistance caused by interactions between molecules and suspended materials in blood
What is turbulence in blood flow?
Swirling action that disturbs smooth blood flow
What is systolic pressure?
Peak arterial pressure during ventricular systole
What is diastolic pressure?
Minimum arterial pressure at the end of ventricular diastole
What is pulse pressure?
The difference between systolic and diastolic pressures
Fill in the blank: Mean arterial pressure (MAP) is calculated by _______.
Diastolic pressure + pulse pressure
What defines hypertension?
Abnormally high blood pressure greater than 140/90
What is hypotension?
Abnormally low blood pressure
What assists venous return to the heart?
Venous valves, muscular pump, and respiratory pump
What is capillary exchange?
Chemical and gaseous exchange between blood in capillaries and interstitial fluid
What drives filtration in capillaries?
Hydrostatic pressure
What is osmosis?
Movement of water across a membrane from lower to higher solute concentration
What is bulk flow?
Continuous net movement of water out of capillaries through tissues back to the bloodstream
What factors make diffusion efficient?
- Short distances involved * Steeper concentration gradient * Smaller solute size
What is capillary filtration?
Water and small solutes are forced across the capillary wall
What happens during reabsorption?
Movement of water back into capillaries driven by osmosis
