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67 Cards in this Set

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Endocardium
inner lining of the heart; simple squamous (endothelium) + CT
Epicardium
outer lining of the heart; simple squamous (mesothelium) + CT (adipose)
Myocardium
actual heart muscle; cardiac muscle + purkinje fibers
What structures are continuous w/ the Endocardium's endothelium & basal lamina?
they are continuous with endothelium of blood vessels that enter & leave the heart
What connects the Endocardium to the Myocardium?
Subendothelial layer of fine collagenous fibers and smooth muscle
_____ & _____ are fibrous extensions of the endocardium.
atrioventricular valves, chordae tendinae
The outermost coat of the eipcardium is formed by_______ cells, a serosa (not adventitia) which releases_______.
mesothelial, lubricating fluid
What type of tissue is just deep to the mesothelial layer of the epicardium and what structures does it contain?
Loose CT- mostly adipose, coronary vessels and nerves.
What type of tissue replaces cardiac myocytes following myocardial infarction?
After 3 days, inflammatory cells infiltrate tissue. Eventually Non-Contractile CT Scars replace the cardiac myocytes.
Is cardiac muscle striated?
yes
Intercalated Discs
“spot welds” of desmosomes & gap jnxs connecting cytoplasm of each cell to the cytoplasm of neighbors. Cardiac myocyte contraction initiates depolarization and contraction of downstream neighbors.
Where are cardiac myocyte nuclei located?
centrally
Sinoatrial Node
Pacemaker of the heart. Contains modified cardiac m. cells concentrically arranged around a Nodal Artery. Impulse spreads from this node via specialized conduction fibers to the AV node.
Atrioventricular Node
Located in the septal wall of the Right Atrium. Appears similar to cells of the SA node. The AV node sends impulses down the Bundle of His, which is composed of Purkinje fibers.
Purkinje fibers
modified cardiac muscle cells just deep to the Endocardial layer; filled with Glycogen and transmit APs much faster than cardiac myocytes
Where do Purkinje Fibers travel in the heart?
from the AV node to the apex of the heart while also sending branches to the right & left ventricular walls
What is the depolarization pathway in the heart from SA node to ventricular walls?
SA node→ R. & L. Atria

AV node

R. & L. Bundle Branches(purkinje fibers)

R.& L. Ventricles
What is the significance of Purkinje Fiber conduction?
allows the heart to squeeze blood from the apex out rather than pushing blood to the apex; contraction has been described as a “wringing out.”
What is the fnx cardiac fibrous skeleton w/ respect to insulation?
forms layer of insulating CT that electrically isolates atria from ventricles; forms rings around the major vessels, AV canals, and the upper portion of the IV septum; prevents AP passing from atria to ventricles.
Sympathetic input from the spinal cord via the ______nerves accelerates & strengthens heartbeat.
cardiothoracic splanchnic
Parasympathetic input from the_____, via the right and left _____ nerves, slows the heartbeat.
brainstem, vagus
Symapthetic and Parasympathetic inputs act on the ______.
SA node
Epinephrine/norepinephrine: released by ______ - increase speed & power of contraction
suprarenal (adrenal) glands
In hypertension (too much blood volume) cardiac muscle cells in the_____and______ are stretched.
right atrium, IV septum
In response to hypertension, myocytes release ______hormones to increase urine production as well as______hormones to dump fluid into peripheral tissues and decrease blood volume.
diuretic, vasodilation
Tunica Intima
endothelium + subendothelial CT. Includes internal elastic lamina in larger vessels
Tunica Media
smooth muscle & external elastic lamina (in large vessels)
Tunica Adventitia
dense irregular CT with some elastic fibers
Large vessels have their own blood vessels, ______, and nerves,______, in the tunica _____, which supplies deeper structures of the vessel as well.
vaso vasorum, nervi vasorum, adventitia
What are the 3 categories of arteries?
Elastic (large) → Muscular (medium) → Arterioles (small)
Elastic Arteries
carry blood from the heart to muscular arteries
Describe the 3 tunics of elastic arteries
intima- Elastic fibers form an incomplete internal elastic lamina
media- thick w/ concentric elastic fiber sheets; fenestrated sheets are not the same as the external elastic lamina!
adventitia- thin w/ with elastic & collagen fibers, nerves and vessels.
Muscular Arteries
Deliver blood to organs.
Describe the 3 tunics of muscular arteries
intima- thinner than elastic aa.; well developed internal elastic lamina
media- many circular layers of smooth muscle interspersed with elastic fibers; less distinct external elastic lamina
adventitia- collagen and elastic fibers
Which type of artery has both internal and external elastic laminae?
muscular arteries
Arterioles
carry blood to tissues and capillary beds; very little subendothelial CT
Describe the 3 tunics of Arterioles
intima- thin; internal elastic lamina may be present
media- 1-3 layers of smooth m. w/ some elastic fibers
adventitia- thin layer of loose CT w/ longitudinally arranged collagenous & elastic fibers anchoring it to the surrounding CT
Restenosis
Smooth muscle cell proliferation that may occlude vessel. Occasionally follows angioplasty.
Aneurysm
ballooning out of artery - weakness in arterial wall. Associated with atherosclerosis, syphilis, CT disorders (Ehlers-Danlos syndrome, Marfan’s syndrome)
Capillaries
single layer of endothelial cells separating their lumen from surrounding tissues; almost no discernible media or adventitia although remnants remain to anchor to ECM
Pericytes
surround capillaries; during wound healing, may differentiate into fibroblasts or smooth m. cells
Continuous Capillaries
have a continuous endothelium & basal lamina; No fenestrations; Located through most of the body; contribute to CNS Blood Brain barrier tight jnxs
Fenestrated Capillaries
thin endothelium with large openings closed by basal lamina; located in areas that require substances to pass to/from the blood and surrounding tissues- GI tract, endocrine glands, renal glomerular tubules (no basal lamina), choroid plexus, & ciliary body
Sinusoidal Capillaries
discontinuous; in liver & hemopoietic organs (spleen, bone marrow). Irregular walls, wide gaps between cells, large fenestrations, incomplete basal lamina
Trace blood flow from the heart to the body and back to the heart
Blood from the heart follows → elastic arteries → muscular arteries → arterioles → capillaries → post-capillary venules → muscular venules → large veins → heart
how does blood return to the heart from the periphery against gravity?
valves in the walls of the veins and muscular compression
Varicose Veins
tortuous, dilated veins caused by decease in muscle tone and failure of venous valves. Blood pools and may thrombose within the vessel
Aprrox how much of the blood volume is in the venous system?
~70%
Describe the tunics of veins
intima- endothelial cells & little subendothelial CT
media- 1-2 layers of smooth muscle cells + some elastic and reticular fibers
adventita- several layers of collagen fibers that get larger as the veins expand
which veins have valves?
medium size veins
Vein valves are paired, semilunar fold of______.
intima
What are the factors that push blood through veins back to the heart?
muscular contraction + capillary pressure
What are the 3 large veins?
Superior and inferior vena cava, portal trunk
what differentiates large veins from small veins?
Thick tunica adventitia with collagenous fibers & longitudinal arranged smooth muscle cells
Arteriovenous anastamoses
connections between arterioles & venules; specialized smooth muscle sphincter in the tunica media on the arterial side of the shunt
how does blood flow through arteriovenous anastomes when the shunt is closed?
arterial blood flows into the capillary bed
how does blood flow through arteriovenous anastomes when the shunt is open?
blood bypasses capillary bed & flows into a vein
precapillary sphincters
control the amount of blood flowing into the capillary beds; when contracted, blood bypasses the microvascular bed carrying on down the arteriole
Early in inflammation, macrophages in surrounding CT secrete cytokines which induce expression of _______ by endothelial cells.
E-selectin; Neutrophils bind to selectins & then migrate through the endothelium to reach the inflamed area
Atherosclerosis
Foam Cell (lipid laden macrophage) formation & fatty deposits in intima, frequently due to hypercholesterolemia. These inflamed deposits may block vessel or cause blood clots to form within affected vessels. In arteries clots can break loose & lodge in the heart, brain or other tissues.
deep venous thromboses
clots form inside of veins due to lack of movement or from trauma to the vessel itself. Their presence results in edema since the blood cannot pass the clot easily.
pulmonary embolism
deep venous thrombosis breaks free from its attachment on a vein’s tunica intima, pass through the heart and then block a pulmonary artery or the entire pulmonary trunk.
lymphatic vessels
The fluid, proteins, enzymes, lipids, antibodies, hormones, & other macromolecules in the interstitial spaces are drained by lymphatic vessels & returned to the subclavian veins
Approximately_____ of fluid empties into lymphatics every day.
2-4 Liters; Exception: lymph from the brain and spinal cord drains into cerebrospinal fluid (CSF).
Do lymph vessels have valves? Smooth m.?
Larger lymph vessels have valves to prevent reflux and smooth muscle to propel lymph proximally
Lymph Nodes
Lymph vessels lead to lymph nodes where lymphatic fluid is concentrated and exposed to lymphocytes
Lymphedema
Blockage or destruction of these vessels leads to swelling in the regions of the body that are not getting proper drainage.