(Lecture 12, Chapter 14) Blood Vessels Flashcards
T/F: the vascular walls of all blood vessels have the same composition
False
The vasculature is a _____ system.
closed
Endothelium
- Inner layer of all blood vessels
- In direct contact with blood and fluids in the lumen of blood vessels
What are the 5 types of vasculature?
- Arteries
- Veins
- Arterioles
- Venules
- Capillaries
Vasodilation
Blood vessel widens/relaxes due to decrease in activity of sympathetic nervous system
Smooth muscles in the vasculature are innervated by the __________
sympathetic nervous system
Vasoconstriction
Blood vessel constricts due to increase in activity of sympathetic nervous system
Vascular Tone
Sympathetic activity that is always applied to blood vessels
Elastic Arteries
Arteries with large amounts of elastic tissue in their walls. This applies to many arteries with a large diameter, such as the aorta and the pulmonary trunk.
What makes the elastic tissue in the aorta and pulmonary trunk significant?
They can expand and contract; the aorta stretches during ventricular contraction and recoils during ventricular relaxation (although it still sends blood to the organs/tissues regardless)
How can the elastic arteries lose elasticity?
- Lipid buildup, scarring
- Arteries stiffen with age
Name an important function of elastic arteries.
They act as pressure reservoirs, i.e. they maintain the driving force for blood flow when the ventricles relax
Despite the aorta recoiling during ventricular diastole, blood doesn’t re-enter the heart. Why?
Aortic valve is closed
Why are arterioles known as resistance vessels?
They contain a lot of smooth muscle, so they can affect blood flow by changing in diameter.
T/F: Vasoconstriction causes a decrease in resistance/pressure in blood vessels
False
What characteristic of capillaries allows for the exchange of nutrients and waste between blood and tissues?
Their walls are one cell thick, and some contain pores.
What are the 3 types of capillaries?
- Continuous capillaries
- Fenestrated capillaries
- Sinusoidal capillaries (sinusoids)
Continuous Capillaries
- Plasma membranes of cells form a continuous barrier
- Vessels are interrupted by cellular clefts
- Most common capillaries
- Permeable to water, small solutes, glucose
Fenestrated Capillaries
- Contain pores (fenestrations), making them more permeable than continuous capillaries
- Permeable to glucose, ions, amino acids, hormones
- Found in kidneys, small intestine, endocrine organs
Sinusoids
- Wider, more winding, have very large fenestrations
- Permeable to small molecules, proteins, cells
- Found in bone marrow, spleen, liver
What is the main method of capillary exchange?
Diffusion
How are larger substances transported through capillary walls?
Transcytosis
What blood vessels drain blood from the capillaries? What blood vessels carry blood back to the heart?
Venules, veins
The movement of blood through the veins is facilitated by _______
skeletal muscles
How does the return of blood to the heart overcome the low pressure in the veins?
Valves, pumps, muscle contraction
Laminar Flow
Smooth, streamlined blood flow along the path of the vessel
Turbulent Flow
Blood moves chaotically in vessel due to rough endothelial lining and/or sharp turns in the vessel
How do the walls of blood vessels get damaged over time?
- Shear stress tearing the vessel walls
- Vessels stiffen and can’t stretch
Systolic Blood Pressure
Pressure in arteries during systole; highest mesasured pressure in the cardiovascular system
Diastolic Blood Pressure
Pressure in arteries during diastole; lowest measured pressure in the cardiovascular system
What device is used to measure blood pressure?
Syphgmonanometer
How do we determine blood pressure (i.e. write it)?
Systolic BP/Diastolic BP
Measured in mmHg
Mean Arterial Pressure
- Average blood pressure in the arteries
- Drives blood flow in the cardiovascular system
Where in the cardiovascular system is mean arterial pressure the highest? Where is it lower?
Highest: aorta, arteries
It’s lower in the capillaries, venules, and veins`
What part of the body regulates mean arterial pressure?
The cardiovascular center
How is mean arterial pressure regulated?
- Blood is monitored by receptors
- Signals are sent to the CV center
- Regulation through ANS
Baroreceptors
Monitor blood pressure and send signals to the CV center
Chemoreceptors
Monitor blood acidity and send signals to the CV center
Vagus nerve
- Part of the parasympathetic nervous system
- Decreases heart rate
Cardiac accelerator nerves
- Part of the sympathetic nervous system
- Increases heart rate and contractility
Vasomotor nerves
- Part of the sympathetic nervous system
- Causes vasoconstriction
