CIRCULATORY SYSTEM:

Comprises the blood vascular system and the lymphatic system.
Consists of the heart and blood vessels.
Heart pumps blood to microvascular bed.
Microvascular beds begins with arterioles (smaller than arteries), which lead into capillaries (smallest) which are in dense networks.
These all collect in venules (small veins) which are sent to veins, which sends back to the heart.

The structure of blood vessels:

The walls have an inner lining, made of simple squamous epithelium, called “endothelium”.
There are three zones, sometimes called “tunics” (coats).
The outer connective tissue is called “tunica adventitia’, the muscular tissue “tunica media”, and endothelial layer “tunica intima”.
The tunica intima layer in an artery is going to be endothelium and a little bit of connective tissue and will be called “internal elastic lamina”.
Subendothelial connective tissue is located right underneath the endothelium. Tunica intima is composed of the endothelium, and internal elastic lamina.
There is an elastic layer that is between the tunica media and is a component of the tunica adventitia that is called the external elastic lamina.
“Vasa vasorum” in both artery and vein is an investment of capillaries and nerve tissue into the tunica adventitia.
Elastic arteries: aorta, corotids, etc..They are called this because they have a lot of elastic fibers in the tunica media (elastic fibers produced by smooth muscle). The larger the artery or vein, the smaller the adventitia. Internal elastic lamina is birefringent?  

Arteries:

In Greek means “windpipe”
   Thought to distributed air throughout the body.
Tunics are layers of artery.
Two Types: muscular (distributing) arteries, elastic arteries
Take most of blood through system, and delivers it through arterioles to microcirculatory bed.
 
Distributing arteries:

Most distinctly shows the tunics

Elastic arteries:

consists of the aorta, pulmonary trunk, corotids, subclavian
called “conducting” arteries, not distributing
Aorta is 2.5 cm in diameter in most humans (largest artery).
The larger the artery, the less defined the tunics are.
The tunica media in is loaded with elastic fibers.
Smooth muscle makes the elastic tissue
There is less adventitia and more media in aortas!

Capillaries:

Means “hair’ in latin.
The lumen is about 7-8 microns.
Red Blood Cell’s have to move through in single file.
There is only one cell layer- called the endothelium.
The RBC’s kind of bend because of the protein they contain called “spectrin” which gives it some elasticity, aiding them in moving in single file.
If the RBC’s don’t move through the capillaries in single-file, then ischemia results.
Ischemia is the lack of oxygen coming from RBC’s to muscle.
Capillary bed is 8 times the aorta.
Capillary is made up of epithelium, with pericytes scattered within, which produce new endothelial lining.

There are three types of Capillaries:
Continuous, Sinusoid, and Fenestrated

Continuous: most common type of capillaries, found throughout the body, make up capillary beds.

 Fenestrated: have “fenestrae” which means window/opening.
There are tiny little pores that they have in their endothelium.
Found in lamina propria, endocrine glands, and in the kidney.

Sinusoid: means ‘spaces’. Mold to the shape of the organ. Sinuses means blood spaces. Liver and kidney are good examples of where these are found.

 Atherosclerosis vs. Arteriosclerosis:
Atherosclerosis is the actual plaquing of vessels which forms an eclusion.
The plaque is made up of fat, glycoproteins, cholesterol, etc.
Pomegranate juice (5 glasses a day), and exercise, and diet have been shown to reverse it.
Vessels can’t contract correctly when plaqued.
Arteriosclerosis is when there is also deposits of mineral salts like calcium which hardens the arteries and prevents blood flow, can induces strokes.