Histology: Cardiovascular System and Epithelial Cells Flashcards
What are the two major divisions of the circulatory system?
Blood vascular system and lymphatic vascular system
What are the three layers of the heart?
Endocardium Myocardium, and Epicardium
The inner most layer of the heart
Endocardium
Made up or simple squamous epithelium and subendothelial CT which contains purkinje fibers
Endocardium
Where cardiac muscle cells are located. Makes up the atrium and ventricles
Myocardium
What hormone is found in the atria that decreases BP?
-also inhibits contraction of vascular smooth muscle
Atrial natriuretic protein (ANP, stored granules)
What do the ventricles have that decrease BP?
BNP (stored as proBNP)
The outermost layer of the heart which contains coronary blood vessels and varying amounts of fat
Epicardium
What are the three layers of the blood vessels?
- ) Tunica Intima
- ) Tunica Media
- ) Tunica Adventitia
Made up of a simple squamous epithelium with a basement membrane.
-Corresponds to the endocardium of the heart
Tunica intima
Circularly arranged smooth muscle cells and elastic tissue
-corresponds to the myocardium of the heart
Tunica Media
Made up of CT containing collagen and elastic fibers
-corresponds to the epicardium of the heart
Tunica adventitia
Where we see the vaso vasorum and nervi vascularis
Tunica adventitia
Nourishes the outer layers of the tunica media
Vasa Vasorum
Blood vessel made up of simple squamous epithelium lining the lumen and 1-2 layers of smooth muscle cells
Arterioles
Capilarry with complete endothelial cells, a basement membrane, and gap junctions
Continuous Capillary
The basil lamina of fenestrated capillaries is
Continuous
Located in tissues with substantial fluid transport, such as endocrine glands and the kidneys
Fenestrated capillaries
Found where the relation between blood and parenchyma are needed, like in the liver, spleen, and adrenal gland
Discontinuous (sinusoidal) Capillaries
More collagenous tissue and more loosely constructed. Less elastic and muscular tissue. Wall thinner, collapses readily
Vein
Thin, inconspicuous internal elastic membrane
Tunica intima of veins
Made up of circular smooth muscle, but thinner than an arterial vessel
Tunica media of veins
Thicker than the tunica media, occasionally made up of muscle
Tunica adventitia of veins
The tunica media is incomplete or absent in a
-adventitia is absent and there is an occasional pericyte
Venule
Have no basement membrane and no blood cells in the lumen
Lymphatic vessels
Lymphatic vessels are not found in the
CNS
Are inherently rhythmic, i.e. they contract without nerve supply
Cardiac Myocytes
Reinforces the bases of the valves and insulates the ventricles from electrical activity in the atria
-Where cardiac muscle attaches
Fibrous cardiac skeleton
Atrial and ventricular myocytes have endocrine
functions, they secrete
Hormones
Lower blood volume and blood pressure by promoting the excretion of salt (natriuresis) nd water by the kidneys
Hypotensive hormones
In response to volume expansion, atrial myocytes lower blood pressure by secreting
Atrial natriuretic peptied (ANP)
Not stored in granules in the ventricular myocytes so its production must be up-regulated before synthesis and secretion can occur
proBNP
Blood levels of BNP can be used as an important diagnostic sign of
Congestive heart failure
Promotes clearance of ANP and BNP
CNP
All blood vessels have a
Tunica Intima
Very well developed in arteries, exhibiting varying quantities of circularly arranged smooth muscle to control distribution and blood pressure and circularly arranged elastic tissue
Tunica Media
Relatively thin in arteries, thicker in veins and well
developed in large veins
Tunica adventitia
The blood vessels that supply larger blood vessels
-seen in the adventitia where they nourish the adventitia and outer layers of the tunica media
Vaso Vasorum
Autonomic nerve fibers that innervate the smooth muscle cells of the vessel wall
-found in tunica adventitia
Nervi vascularis
Conserve and regulate the pressure generated by the ventricles while distributing the blood to the vascular beds
Arteries
Have a great deal of elastic tissue, both fibers and
sheets (lamina) in both the intima and media
Large elastic arteries
The elastic tissue in large elastic arteries are made by
the smooth muscle cells in the
Tunica media
As arteries get smaller, how does the composition of their tunica media change?
More smooth muscle and less elastic tissue
Responsible for the drop in arterial blood pressure before blood enters the capillary beds
Arterioles
As blood passes through the arteriolar beds, arterial BP drops from 85 mmHg to
30mmHg
Have an incomplete layer of smooth muscle in their
media and the smooth muscle cells are usually
arranged longitudinally
Metarterioles
Controls the entrance to the capillary bed and regulates the amount of blood that enters
Precapillary sphincter
Contractile stem cells found at intervals along capillaries that are capable of becoming smooth muscle, adipose, osteogenic, or chondrogenic cells
Pericytes
Found on the adluminal side (toward the lumen) of the basement membrane that surrounds capillaries
Pericytes
Continuous capillaries are found in
Muscle, CNS (blood-brain barrier), and gonads
Forces plasma out of the capillaries and into the interstitial tissues
Hydrostatic Pressure
Transcytosis via pinocytotic vesicles transports
Larger molecules
As permeable as capillaries
Venules
Have one to two circular layers of smooth muscle in their tunica media and a more distinct tunica adventitia that has collagen, elastic tissue, and some smooth muscle
Small to medium veins
Large bundles of smooth muscle may be found in the media or adventitia of large veins that are
Inferior to the heart
How can we tell large arteries and large veins with a well developed adventitia apart?
Arteries will have an internal elastic lamina, veins will not
HAve a structure similar to capillaries except their basement membrane is discontinuous or missing altogether
Lymphatic capillaries
About 10% of the interstitial fluid extruded at the arterial end of the a vascular bed is reabsorbed into the
Lymphatics
The tunica intima and inner portion of the tunica media are nourished by
Diffusion from blood in the lumen
Serve as a selective permeability barrier so that substances can be allowed to cross the endothelium to the tunica media and beyond
Endothelial cells
Endothelial cells in many organs respond to various substances by producing a potent but short lived local vasodilator called
Nitric oxide
Converts the vasoinactive angiotensin I to angiotensin II, a potent vasoconstrictor which also inactivates the vasodilator bradykinin
-contained in most endothelial cells
Angiotensin converting enzyme (ACE)
Enable angiogenesis to occur
Endothelial cells
