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Human Structure - Histology - Cardiovascular
Cardiovascular Microstructure from Objectives and Lab Manual
19
Medical
Graduate
09/30/2009

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Term
The Five aspects of the Cardiovascular System are:
Definition

1. A Fluid - Blood Plasma

2. A Pump - the Heart

3. Arteries for carrying blood away from the heart

4. Veins for draining capillaries and returning blood to the heart

5. Capillaries - For supplying O2 and nutrients as well as removing CO2 and metabolic wastes.

Term
What are the three layers of a blood vessel's wall? (internal to external)
Definition

1. Tunica Intima

2. Tunica Media

3. Tunica Adventitia

Term

What is the general microstructure of:

Tunica Intima

Definition

Has three main regions:

A. Endothelium

B. Basla Lamina

C. Subendothelial Layer (Loose CT) (In arteries and arterioles there is a sheet like layer of lamella called the internal elastic membrane)

 

In arteries and arterioles, the subendothelial layer may contain some smooth muscle.

Term

What is the general microstructure of:

Tunica Media

Definition

Extends from the Internal Elastic Membrane to the External Elastic Membrane.

 

Mainly composed of circumfrentially arranged layers of smooth muscle. 

 

Variable amounts of elastin, reticular fibers, and glycoproteins are found surround the smooth muscle from the bordering membranes.

Term

What is the general microstructure of:

Tunica Adventitia

Definition
Longitudinally arranged collagenous tissue.  This layer contains small vessels called vasa vasorum that supply blood to the vessel walls and nervi vascularis that innervates the smooth muscle of the wall.
Term

Describe the wall and size of:

Capillaries

Definition

Small, red blood cell (RBC)‑sized endothelial tube

No other components

Term

Describe the wall and size of:

Postcapillary Venule

Definition

Large Endothelial Tube

No other componenets

Term

Describe the wall and size of:

Muscular Venule

Definition

Small sized vessel

Media with one or two layers of smooth muscle

Lots of adventitia

Term

Describe the wall and size of:

Arteriole

Definition

Small vessel

Media with one or two layers of smooth muscle

Little adventitia

Term

Describe the wall and size of:

Artery

Definition

Large vessel

Thick media with lots of elastin

Term

Describe the wall and size of:

Muscular Artery

Definition

large vessel

Thick media (lots of smooth muscle)

Thinner adventitia

Term

Describe the wall and size of:

Vein

Definition

large vessel

Thin media

Thicker adventitia

Term
What type of vessels do you expect to find a vasa vasorum and why?
Definition
Vasa Vasorum is present within large artieries and veins only.  It is only present within these types of vessels because in the smaller types of vessels nutrient and wastes can readily diffuse from the blood to the layers of the vessels.
Term
Why do large artieries have so much elastin within their walls?
Definition
In order to maintain constant blood flow throughout the body, the elastin allows major arteries to distend during systole and recoil during diastole.  This maintains constant blood flow through the vessels and initially during recoils forces a small amount of blood back towards the heard and forces closing of the pulmonary and aortic valves.
Term
What are the three main types of capillaries?
Definition

1. Continuous Capillaries

2. Fenestrated Capillaries

3. Discontinuous Capillaries

Term
What are the six major functions of endothelial cells?
Definition

1. Maintaines a selectively permeable barrier
Simple Diffusion, Active Transport, Pinocytosis, Receptor Mediated Endocytosis.

 

2. Maintenance of a nonthrombotic barrier

Secretion of Antiocadulants, Antithrombogenic Agents, and Prothrombogenic Agents

 

3. Modulation of blood flow and vascular resistance

Secretion of vasconstrictors and vasodilators

 

4. Regulation and modulation of immune responses

Regulates leukocyte migration by expression of adhesion molecules

 

5. Hormonal Synthesis

Growth factor secretion

 

6. Modification of lipoproteins

Production of free radicals

Term
Why is the tunica media of veins typically less prominent than that of similarly sized arteries?
Definition
The tunica media is less prominant because the veins do not need to dilate and recoil.  Instead the vein has semilunar valves that only allow blood to flow in one direction (towards the heart)
Term
Apart from blood flow, what other function do arterioles and muscular arteries have?
Definition
They have the ability to constrict between 60% and 100% of their size to direct the flow of blood to where it is most needed by stopping blood flow to some capillaries.
Term
What are metarterioles?
Definition
Arterioles which give rise and have capillaries connected to them.
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