(1) Blood Vessels; Part 1 (Martin) Flashcards
***Self Review***
What are the three layers within a blood vessel?
Intima
Media
Adventitia
***Self Review***
What differentiates the intima from the media?
Internal elastic lamina
***Self Review***
What is the clinical importance of the internal elastic lamina?
VERY common site for damage within vessels
***Self Review***
Describe a elastic artery
High elastin content
–> Allows for expansion during systole and recoil during diastole
Becomes less compliant with age
***Self Review***
Describe a muscular artery
Circumferentially oriented smooth muscle
Contribues to arteriolar:
Contraction=vasoconstriction
Relaxation=dilation
***Self Review***
Describe arterioles
Main point of physiologic resistance to blood flow
Resistance to fluid flow is INVERSELY proportional to the fourth power of the diameter
***Self Review***
What is contained within the adventitia?
Vasa Vasorum
“Vessels of the vessels”
Small arterioles supply O2 to the outer media of large arteries
***Self Review***
Describe the characteristics of capillaries
Diameter of RBC
No media
contains pericytes
***Self Review***
Describe the characteristics of veins
Most inflammatory reactions ooccur here
Larger lumens, thinner and less organized walls
Contains about 2/3 of total blood volume
Less rigid
Reverse flow due to gravity prevented in the extremities by venous valves
***Self Review***
Describe lymphatics
Thin walled, lined by specialized endothelium
Returns interstinal tissue and inflammatory cells to the bloodstream
Transports bacteria etc, tumor cells
*THE PATHWAY FOR DISEASE DISSEMINATION
Where does gas and nutrient exchange occur in the vasculature?
Capillary
Where is blood pressure regulated within the vasculature?
Arteriole
What structure is contained within veins but NOT arteries?
ONE WAY VALVES
What are the three primary vascular anomalies?
- Aneurysms
- Arteriovenous malformations (AVM)
- Fibromuscular dysplasia
What is an aneurysm?
Localized abnormal dilation of a blood vessel or the heart
How does an aneurysm develop?
NOT present at birth
Develops over time due to underlying defect in the media of the vessel
Describe what arteriovenous malformations (AVM) are:
When arteries directly connect with veins without intervening capillaries
They are tangle, worm-like vascular channels with significant PULSATILE arteriovenous shunting with high blood flow
Large or multiple AVMs may shunt blood leading to cardiac failure
Describe what fibromuscular dysplasia is
Focal irregular thickening
in medium and large muscular arteries
How does fibromuscular dysplasia typically arise?
USUALLY developmental defect
rarely rises from trauma
Berry Aneurysms
Where does this commonly occur?
Circle of Willis
Berry Aneurysms
What is the most common clinical report of patients with Berry Aneurysms?
“The worst headache I’ve ever had”
Berry Aneurysms
Anatomically, where are they frequently found within the circle of willis?
Branch points of the anterior circulation
Berry Aneurysms
Most frequent cause?
Subarachnoid hemorrhage (SAH)
Berry Aneurysms
Typical size?
>10 mm in diameter
Berry Aneurysms
Approximatly 1/3 of ruptures are associated with…
Acute increases in intracrainal pressure
eg Straining at stool, Sexual orgasm…nice
Berry Aneurysms
Fatality percentage?
25-50% die with first rupture
-Repeat bleeding common in survivors
What is a mycotic aneurysm?
Can be one of the three…
- embolization of a SEPTIC EMBOLUS which is usually a complication of infective endocarditis
- an extension of an adacent suppurative process
- circulating organisms directly infecting the arterial wall
What are the 4 types of aneurysm?
- Saccular (berry) ***most common
- Giant
- Fusiform
- Mycotic
Describe the appearance of an AVM:
Wormy, tangled
Why would you surgically induce an AVM?
To generate a arteriovenous fistula to provide vascular access for chronic hemodialysis
Describe the appearance of fibromuscular dysplasia
“String of beads”
Focal irregular thickening in medium and large muscular arteries