HE 21/22 Preview Flashcards
What three layers make up the wall of a blood vessel?
Tunica Intima
Tunica Media
Tunica Adventitia
What two layers make up the tunica intima?
Endothelium layer: simple squamous cells joined by tight junctions, basal lamina separates from next layer
Subendothelial layer: CT, smooth muscle, macrophages
What separates the subendothelial layer from the tunica media?
Internal Elastic Lamina (IEL): fenestrated sheet like rubber, stains hot pink with H&E stain
In which layer do plaques form in the vessel wall?
In the subendothelial CT layer
What cells are the primary makeup of the tunica media?
Smooth muscle cells
How do the smooth muscle cells in the TM work?
They are connected by gap junctions which allow them to contract as a unit. The nerves that innervate them are not found in the TM.
What is another function of the smooth muscle in the TM layer if they are not contractile cells?
They can also be secretory cells.
They secrete many layers of fenestrated elastic lamina.
What separates the TM from the TA?
The smooth muscle cells in the TM secrete and make the external elastic lamina or (EEL) between the two layers. It is fenestrated, but less prominent than the IEL.
How can you tell if the smooth muscle in the TM is contractile or secretory?
When stained and observed, contractile smooth muscle has corkscrew nuclei and few elastic fibers present. Orcein makes elastic fibers show up black.
Describe the tunica adventitia.
It is the outermost layer of vessels. It is made of fibroelastic connective tissue that is continuous with the surrounding tissues. It is what you go through when trying to expose a vessel in lab. It is what envelops the neurovascular bundle.
Where do the layers of the blood vessel wall get their nutrients from and also dispose of their waste?
The TI and the inner 1/2 of the TM get their blood supply from the inside of the vessel itself. The outer part of the TM and the TA get their nutrients from the Vasa Vasorum which are vessels in the TA.
Where are the nerve fibers that innervate the smooth muscle in the TM?
Postganglionic cells are found in the TA where they release their neurotransmitters that diffuse into the TM and the signal is distributed through gap junctions.
What veins drain blood from the head and neck?
Internal and External Jugular
What veins drain blood from the upper extremities?
Subclavian veins
What blood vessel drains blood from the jugular and subclavian veins?
Brachiocephalic
