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87 Cards in this Set

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What are the three layers of blood vessels?
Tunica Intima
Tunica Media
Tunica Adventitia
Tunica Intima
Structure?
This is the innermost layer.
It has a lining of endothelial cells resting on a basal lamina/basement membrane. The endothelium is simple sqaumous epithelium.
The endothelium of Tunica Intima is made of what type of cells?
Simple Squamous Epithelium
The Endothelium of the Tunica Intima plays a role in?
1) Transporting substances to and from the blood.
2) Vascular smooth muscle tone.
3) Control of blood clotting.
4) Attachment of WBC's to the vessel wall.
Subendothelial Layer
A layer of CT that may be present under the endothelium of the Tunica Intima.
Tunica Media
Structure?
Middle layer.
Varies in thickness and composition depending on the vessel. It contains smooth muscle, elastic fibers, and type III Collagen fibers in varying ratios.
What is the purpose of having Type III Collagen in the Tunica Media?
Recoil
Tunica Adventitia
Outer layer
Collagen and elastic fibers blend with the surround CT.
What are Vasa Vasorum and where are they found?
"Vessels of Vessels"
Found in the Tunica Adventitia and outer part of the Tunica Media of large vessels.
What is the function of Vasa Vasorum?
Provide nutrients and carry away wastes from the media and adventitia.
What provides nutrients to the Tunica Intima and the inner part of the Tunica Media?
Provided for by diffusion from and to the blood in the lumen of the vessel.
Nerves that are part of the ________ nervous system innervate smooth muscle in the Tunica ______, causing vasoconstriction. The neurotransmitter here is _______.
Sympathetic NS
Tunica Media
Norepinephrine.
What makes blood vessels dilate?
NT (such as ACh) binds to endothelial cells of Tunica Intima causing the release of NO, which travels to adjacent muscle cells and causes them to relax.
The nerves leading to dilation of blood vessels are part of the _____ NS.
Parasympathetic.
Large Elastic Arteries (examples)
Conducting arteries
Include the aorta and its branches (femoral, posterior tibial, brachial, etc...)
What are arteries classified as?
Elastic
Muscular
Arterioles
Large Elastic Arteries conduct blood to ?
Muscular Arteries
In large elastic arteries, what makes up the Tunica Intima?
Consists of the endothelium and its basal lamina and a thick subendothelial layer
In large elastic arteries, what separates the Tunica Intima from the Tunica Media?
An internal elastic lamina separates them but it is usually difficult to distinguish from the adjacent elastic laminae in the Tunica Media under the microscope.
Large Elastic Arteries
Structure of-
Tunica Intima
Tunica Media
Tunica Adventitia
Tunica Intima- Endothelium plus basal lamina plus a thick subendothelial layer

Tunica Media- Extremely thick layer of concentric layers of elastic tissue, collagen fibers, and smooth muscle cells.

Tunica Adventitia- Relatively thin layer of CT. Has Vasa Vasorum, lymphatics, and nerves.
With age, the ratio of elastic to collagen fibers ___?
decreases
Vasa Vasorum are present in what part of large elastic arteries?
Outer third of Tunica Media and all of the Tunica Adventitia
Tunica Adventitia of Large Elastic Arteries.
relatively thin layer of CT.
Vasa vasorum, lymphatics and nerves are present here.
Muscular Arteries
Which ones?
Function?
Distributing Arteries.
Include most of the named arteries of the body.
The function of these arteries is to distribute blood under high pressure to body regions.
A prominent internal elastic lamina separates the Tunica Intima from the Tunica Media in these vessels.
Muscular Arteries
Structure of the Tunica Intima of Muscular Arteries.
relatively thin layer of endothelium and its basal lamina and a thin subendothelial layer
Structure of the Tunica Media of Muscular Arteries.
Relatively thick layer of smooth muscle with some collagen and elastic fibers. There may be as many as 40 concentric layers of smooth muscle.
Do Muscular Arteries have elastic laminas?
Yes- two. The external separates the media from the adventitia but is not as prominent as the internal.
Structure of the Tunica Adventitia of Muscular Arteries
layer of CT that may have vasa vasorum, lymphatics and nerves
Aneurysm
What is it?
Why does it happen?
An aneurysm is a weakness in the wall of an artery that causes dilation in that area. It may result in the rupture of the artery. The weakness may be due to a developmental defect of, or damage to, the TUNCIA MEDIA.
A weakness in what part of an artery could lead to an aneurysm?
Tunica Media
Arteriosclerosis
Hardening of the arteries
What is the most common type of Arteriosclerosis?
Atherosclerosis
What is atherosclerosis?
What causes it?
Fibrolipid plaques form in the Tunica Intima.
Though that an inflammatory response caused by LDL cholesterol in the intima of the vessel causes most of these plaques.
When do most MI's occur?
When a plaque in a coronary artery ruptures and a clot forms, blocking the flow of blood to the heart.
Arterioles
Size?
Function?
Vessels of less than 0.5 mm diameter.
Functions-
1) slow down blood pressure before it reaches the terminal vascular bed (capillaries)
2) regulate blood flow through the capillary beds.
The tonus in arterioles has a marked effect on ____?
blood pressure
Arterioles
Structure of-
Tunica Intima
Tunica Media
Tunica Adventitia
Tunica Intima- endothelial cells plus basal lamina plus a thin subendothelial layer

Tunica Media- the thickest layer, made of smooth muscle.

Tunica Adventitia- thin layer of collagen and elastic fibers
Structure of the Tunica Media of Arterioles?
The thickest layer.
Consists of smooth muscle (1-5 layers).
Structure of the Tunica Adventitia of Arterioles?
thin layer of collagen and elastic fibers
Metarterioles
What are they?
Structure?
Where do they go?
Small vessels that branch off arterioles.
They have a lining of endothelium and its basal lamina and a discontinuous layer of smooth muscle in the Tunica Media.
They branch into capillary bed.
Constriction of the smooth muscle in _____ helps to regulate blood flow through the capillary beds.
Metarterioles
Precapillary sphincters
Smooth muscle at the point where capillaries branch off metarterioles and arterioles.
What would be the result of constriction of the precapillary sphincter?
Can stop blood flow through a capillary bed
Capillaries
Size?
Site of?
Vessels of very small diameter (7 um).
Site of interchange between blood and tissue fluid.
What are the three types of capillaries?
Fenestrated Capillaries
Continuous Capillaries
Sinusoidal Capillaries
Fenestrated Capillaries
Large openings in the wall that allow for exchange of molecules.
Where would you find Fenestrated Capillaries?
Examples are found in the kidney, intestine, endocrine glands and other tissues where exchange between the circulatory system and the tissues is significant.
Continuous Capillaries
No openings in the wall, limiting exchange of molecules.
Where would you find continuous capillaries?
Examples include muscle, CT, and nervous tissue.
Sinusoidal Capillaries
Large diameter. They have fenestrations and a discontinuous basal lamina.
Phagocytic cells are often associated with the wall of ?
Sinusoidal Capillaries
Arteriovenous (A-V) Anastomosis
This is a direct communication between arterial and venous circulation. These vessels have thick muscular walls proximally, and a wider lumen distally.
These collect blood from capillaries.
Venules
Structure of the Tunica Intima of Venules?
Made only of endothelium and its basal lamina. The endothelial cell attachment is weak, making venules leakier than other vessels.
What makes venules leaky? Why is this important?
The endothelial cell attachment of the Tunica Initima is weak.
Leukocytes can escape here during the acute inflammatory reaction.
Structure of the Tunica Media of Venules?
One layer of smooth muscle. May be absent.
Structure of the Tunica Adventitia of Venules?
Made of collagen fibers
These conduct blood toward the heart under low pressure.
Small to medium muscular veins.
Structure of the Tunica Intima of Small to Medium Veins?
Consists of the endothelium and its basal lamina. There may be a subendothelial layer.
Valves are folds of the _____ that project into the _____ facing ____, to prevent backflow of blood. They may be found in veins located ___.
Tunica Intima
Lumen
Downstream
Below the heart
Structure of the Tuncia Media of Small to Medium Veins?
thin layer of smooth muscle, collagen fibers, and elastic fibers
Structure of the Tunica Adventitia of Small to Medium Veins?
Relatively thick layer of CT.
What structural changes would you see in varicose veins?
Larger diameter. Elongated. Thickening of walls due to increase in CT in the intima and more smooth muscle cells in the media.
What causes varicose veins?
Due to prolonged increase in venous pressure
Where are you most likely to have varicose veins?
superficial veins of the lower extremity, the lower esophagus, and the anal canal (hemorrhoids)
Large veins
Return blood to the heart under low pressure
Structure of the Tunica Intima of Large Veins?
Relatively thin layer consisting of the endothelium and its basal lamina and a subendothelial layer
Structure of the Tunica Media of Large Veins?
relatively thin layer of CT and smooth muscle
Large Veins
Structure of-
Tunica Intima
Tunica Media
Tunica Adventitia
Tunica Intima- relatively thin. endothelium plus basal lamina plus subendothelial layer.

Tunica Media- relatively thin. CT and smooth muscle.

Tunica Adventitia- thick layer of CT. Also has Vasa Vasorum and lymphatics.
What is the inner layer of the heart called?
Endocardium
What makes up the Endocardium?
The inner layer of the heart consists of the endothelium plus its basal lamina and a subendothelial layer of CT.
Subendocardial Layer
This is a CT layer between the endocardium and the myocardium.
What is contained in the Subendocardial Layer of the heart?
Veins, Nerves of the ANS, and Purkinje Fibers.
The ____ of the ____ Layer make up the Atrioventricular (AV) Bundle.
Purkinje Fibers
Subendochondrial
The AV Bundle divides into ____ which are located ____.
Right and left branches.
on either side of the ventricular septum and extending toward the apex of the heart. The right and left bundle branches spread around each ventricle and back toward the base of the heart.
What is the result of failure of the AV Bundle to conduct the normal cardiac impulse?
arrhythmias or, if there is a complete bundle block, complete dissociation between the atrial and ventricular rates of contraction.
Myocardium
the middle layer of the heart
thick layer of cardiac muscle cells
Epicardium
Layers and Structures?
Mesothelium- lying on a CT layer
Subepicardial- layer of CT that separates the epicardium and the myocardium.
What are the layers of the heart from outside in?
Pericardium
Epicardium
Myocardium
Endocardium
What is contained in the subepicardial portion of the Epicardium of the heart?
blood vessels, nerves, ganglia of the parasympathetic NS and adipose tissue
Skeleton of the heart-
Made of?
Function?
Limits?
The dense CT rings that surround the cardiac valves.
Provides attachment for the cardiac muscle fibers of the atria and ventricles and for the cusps of the AV valves.
It limits the diameter of the AV and arterial orifices during the different phases of the cardiac cycle.
Cardiac Valves are made out of what?
Dense fibrous CT lined by endothelium.
What attaches the cusps of the tricupsid and mitral valves to the papillary muscles?
Chordae Tendinae
Lymphatic Capillares
Structure?
Function?
Blind-ended vessels that look very much like blood capillaries. They may have a fenestrated endothelium that has a discontinuous basal lamina to allow large molecules and cells to enter.
The function is to collect surplus tissue fluid.
Lymphatic Vessels
Structure?
Function?
Resemble veins or venules, although their wall may be thinner. They have valves to prevent backflow.
Convey lymph collected by lymphatic capillaries to the lymphatic ducts.
Lymphatic Ducts
Structure?
Function?
Their structure is similar to that of veins.
Return lymph to the blood circulatory system. (thoracic duct and right lymphatic duct)