Circulatory 2 Flashcards
Pulse pressure
Difference between systolic and diastolic pressures
Pulse pressure does what in vessels farther from the heart?
Widens
Mean arterial pressure continuously ___ throughout the circulatory system
Declines
Mean arterial pressure is more dependent on which one: systolic or diastolic pressure?
Diastolic pressure; more time is spent in diastole than systole
Where is the greatest decrease in arterial pressure?
Across the arterioles
Why does the pulse pressure widen in farther from the heart?
Systolic pressure increases and diastolic pressure decreases
Four alterations in pressure profile
- Widened pulse pressure farther from the heart
- High frequency components are dampened
- Systolic peak increased and waveform narrowed
- Late diastolic hump in the waveform
Possible causes for the diastolic hump
Reflection at branch points, vascular tapering, or decrease in arterial compliance
Three layers of the vessel wall
Tunica intima, tunica media, tunica adventitia
Tunica intima in the artery wall
Subendothelial connective tissue; internal elastic lamina
Tunica media of the artery wall
Smooth muscle cells and external elastic lamina
Tunica adventitia of the artery wall
Mostly connective tissue with some smooth muscle cells, vasa vasorum, innervation
Tunica intima of the vein wall
Subendothelial connective tissue; NO internal elastic lamina
Tunica media in the vein wall
Less smooth muscle cells, NO external elastic lamina
Tunica adventitia
Well-developed connective tissue with some smooth muscle cells, with vasa vasorum
Main differences between an artery and vein
Artery has elastic lamina, more smooth muscle, and less connective tissue
Compliance properties of arterial wall components
Elastic lamina - highest compliance
Smooth muscle - less compliant than elastin, but more compliant than collagen
Collagen - lowest compliance
Continuous capillary
Continuous endothelial cells, no fenestrations, tight junctions between cells, continuous basal lamina
Where are continuous capillaries found?
In muscle and connective tissues
Fenestrated capillaries
Continuous endothelial cells with fenestrations with or without diaphragms and continuous basal lamina
Where are fenestrated capillaries?
Found in kidneys and intestines
Discontinuous (sinusoidal) capillary
Discontinuous endothelial cells separated by wide spaces, discontinuous basal lamina
Where are discontinuous capillaries?
Liver, bone marrow, spleen
Wall thickness/lumen diameter ratio
The higher it is, the greater the control of vessel diameter and blood flow
Pre-capillary sphincters
Highest ratio and greatest control
