Cardiovascular 1 Flashcards
What are the examples of elastic arteries?
-aorta and it’s main branches, common carotid, Subclavian, common iliac
Why are named elastic arteries larger?
Due to the number of elastic fibers in tunica media (40-70 layers)
What are the main characteristics of elastic arteries?
Imbricated: the elastic fibers are arranged in concentric layers like shingles on the roof.
Have fenestrations-permitting diffusion of nutrients
Vascular smooth muscle between layers of elastic fibers
Clinical: Marfan syndrome
What is the structural significance of elastic arteries?
- expansion of vessel wall to accommodate the large volume of blood during systole
- elastic recoiling to maintain intra vascular pressure
Differentiate the layers of the elastic artery
T. Intima: endothelial cells, sub endothelial connective tissue, IEL not conspicuous
T. Media: 40-70 layers of elastic lamellae, smooth muscle cells, type 3 collagen
T. Adventitia- dense irregular connective tissue. Prevents excessive expansion of vessel
Describe the T media within an elastic artery (such as the aorta)
- Large amount of elastic fibers in tunica media- imbricated arrangement
- Note smooth muscle cells between elastic fibers (elongated nuclei)
What are the examples of muscular arteries?
All medium sized vessels that are named+ brachial, radial, femoral, tibial, etc
What are muscular arteries also known as?
Also refferred to as distributing arteries/named arteries
Most abundant in the body
What is the main differentiation of muscular arteries?
Named muscular arteries- as they contain more smooth muscles in the tunica media than elastic fibers
As they become smaller than elastic arteries, they lose the elastic fibers, which now form external elastic lamellae (EEL) between tunica media and adventitia
-EEL is characteristic of muscular arteries
What is the structural significance of muscular arteries?
Serves as a muscular conduit to distribute blood from elastic vessels to smaller vessels
Describe the tunica intima of the muscular artery
Distinct internal elastic artery
A distinguishing characteristic - undulating (scalloped) appearance
Describe the tunica media
8-40 layers of smooth muscle cells arranged in circular fashion
-few elastic fibers & collagen
Distinct external elastic lamina
Describe the tunica adventitia of a muscular artery
Dense connective tissue with collagen & elastic fibers
-vasa vasorum and nerves
Describe the tunica intima of a small artery
Endothelial cells, minimal sub endothelial connective tissue
IEL- present
Describe the tunica media of a small artery
3-8 layers of smooth muscle cells, arranged in circular fashion
Describe the tunica adventitia of the small artery
Connective tissue with type 1 collagen, I’ll-defined, blends with surrounding connective tissue
Describe arterioles
Smallest arteries- below 0.1 mm in diameter-can be closed down to generate high resistance to flow (resistance vessels) major determinants of blood pressure (R inversely proportional to 1/D^4)
What is the tunica intima of the arterioles comprised of?
Endothelium
Describe the tunica media of the arteriole
1-2 layers of smooth muscle cells
Describe the tunica adventitia of arteriole
Ill defined: merges with surrounding connective tissue
What is the significance of arterioles?
Their small radius provides increased resistance to flow of blood, thereby maintaining the blood pressure
What is the function of the precapillary sphincter?
Regulated the flow of blood into the capillary bed, as per physiological demands
What are the examples of precapillary sphincter function?
- Blood flow increased to G.I. tract after food intake & at the same time decreased flow to other areas of the body
- increased blood flow to skeletal muscles during exercise