Circulatory System Flashcards
circulatory system consists of
heart, blood vessels, and lymphatic system
3 common layers/tunics of large blood vessels
Tunica intima
Tunica media
Tunica adventitia
Large vessels have other smaller vessels(vasa vasorum) branching through…
adventitia and outer part of the media
Veins have more vasa vasorum than arteries?
True
Large vessels may have more of these components in adventitia
lymphatic vessels and nerves
Tunica intima
endothelium + underlying sub endothelial CT. Includes internal elastic lamina in larger vessels
primarily smooth muscle cells and also external elastic lamina
Tunica media
Tunica adventitia
fibroelastic CT (dense irregular CT with small amounts of elastic fibers)
How are arteries classified?
large (elastic), medium (muscular), and small (arterioles)
Elastic (Conducting) arteries
conduct blood to muscular arteries.
Examples of conducting arteries
aorta, pulmonary, brachiocephalic, common carotid, subclavian, and common iliac arteries
elastic fibers of intima form an
incomplete internal elastic lamina
arteries have a subendothelial layer of
loose CT which contains collagen and elastic fibers and fibroblasts
arteries have no distinct
external elastic lamina
muscular (distributing) arteries deliver
blood to organs
Muscular arteries are innervated by
postganglionic sympathetic nerve fibers
The intima of muscular arteries is ________ than that of elastic arteries
thinner
muscular arteries have a well developed
internal elastic lamina
The subendothelial CT of muscular arteries lack
smooth muscle cells
in muscular arteries the thick external elastic lamina is located
at edge of Tunica media
adventitia may be as thick as media, with
collagen and elastic fibers
In arterioles, media has 1-3
layers of smooth muscle cells with occasional elastic fibers
adventitia
layer of loose connective tissue with longitudinally arranged collagenous and elastic fibers
capillaries have a
single layer of endothelial cells
in arterioles, internal elastic lamina
may or may not be present
capillaries are surrounded by
thin sheath of reticular and collagenous fibers and some pericytes
Pericytes are basically
mesechymal-like stem cells
In wound healing, pericytes may differentiate into
fibroblasts or smooth muscle cells
continuous (somatic) capillary
continuous endothelium and basal lamina
continuous capillaries have no
fenestrae
For transcytosis, continuous (somatic) capillaries have numerous
pinocytotic vesicles
Where are continuous capillaries located?
muscle, CT, CNS, exocrine pancreas and gonads
In the CNS, continuous capillaries have a type of tight junction which
contributes to the blood-brain barrier
fenestrated endothelium in the glomerular capillaries have no
diaphragms
fenestrated capillary
attenuated endothelium with large fenestrae – closed by thin diaphragms. continuous basal lamina
fenestrated capillaries are located in
mucosa of GI tract, endocrine glands, renal, kidney, choroid plexus, and ciliary body
Discontinuous capillaries are found in
liver and hemopoietic organs( bone marrow, spleen)
Discontinuous capillaries have ____ ____ between cells and thus have an _________ ______ ______
Discontinuous capillaries have wide gaps between cells. Incomplete basal lamina
Veins return
blood to the heart
Veins start as _____
venules
Intima of veins
endothelial cells
Media of veins have
1-2 layers of smooth muscle cells
Postcapillary venules
receive blood from capillaries
postcapillary venules have an incomplete layer of _____ which becomes more complete as vessel gets larger
pericytes
Postcapillary venues are an important site of activity in
inflammation
muscular venules
1-2 layers of smooth muscle and thin tunica adventitia. No pericytes
Name some large veins
superior and inferior vena cava, portal trunk
Intima od small to medium size veins (1-9mm ) may have a
thin sub endothelial connective tissue layer
Large veins have a thick adventitia with
collagenous fibers and longitudinal arranged smooth muscle cells
Small to medium size veins may have _____ to prevent retrograde blood flow
valves
Valves are
paired, semilunar folds of the intima covered with endothelium
arteriovenous anastamoses
connections primarily between arterioles and venules
At the anastamoses between arterioles and venules there is a
specialized tunica media with a sphincter
When shunt is closed in arteriovenous anastomoses…
arterial blood flows into capillary bed
When shunt is open in arteriovenous anastomoses…
blood bypasses capillary bed and flows into vein
Some microvascular beds have a _________ __________ which controls the amount of blood flowing into the capillary
precapillary sphincter
fluid scavenged by the lymphatic systems filtered by
lymph nodes and recycled into venous circulation at the base of the neck
Plasma proteins, fluid, enzymes, lipids, antibodies, hormones and other macromolecules leak from
blood vessels and bathe tissues and interstitial spaces
lacteals in the intestine are an important route of
fat absorption
Lymph flows in only one ________ toward the base of the neck
direction
lymphatic capillaries have no
basal lamina
lymphatic vessels originate in CT as
closed-end anastomosing capillaries
What areas of the body has no lymphatic system
CNS and bone marrow
In smaller vessels, fine anchoring filaments attached to ________ _______ hold the vessel open
perivascular collagen
Main thoracic duct and right lymphatic duct are structurally similar to
veins, with smooth muscle present
what prevents back flow of lymph
paired cusp valves
skeletal muscle has lymphatics only in
perimysium
atherosclerosis
foam cell formation and fatty deposits in intima—may block vessel
smooth muscle cell proliferation that follows angiolasty procedure. may occlude vessel
restenosis
Aneurysm
ballooning out of artery–weakness in arterial wall
varicose veins
tortuous, dilated veins, primarily in legs of older person. caused by decrease in muscle tone and failure of venous valves
endothelial cells produce _________ from arachidonic acid
prostacyclin
Prostacyclin inhibits
platelet adhesion and clot formation
endothelial cells secrete nitric oxide which causes
smooth muscle in the tunica media to relax (vasodilator)
when endothelial cells secrete endothelia-1 the response is
vasoconstriction
endothelial cells also regulate
the traffic of inflammatory cells
early in inflammation, macrophages in surrounding connective tissue secrete
cytokines (TNF-alpha, IL-1) which induce expression of E-selectin by endothelial cells
Neutrophils bind to selectins and then
extravasate by migration through the endothelium
mother’s circulatory system is not continuous with that of the fetus, therefore
no blood is exchanged, only material carried in the blood
Exchange between the mother and fetus occur at the interface where the
umbilical fuses with the uterine walls (placenta)
The fetal side (syntrophoblast) of an outer layer of
multinucleated synctiotrophonlasts
inner layer of heart homologous to the intima
endocardium
middle layer of heart homologous to the media
myocardium
outer coat of heart corresponding to the adventitia
epicardium
endocardium is lined by
endothelium- continuous with blood vessels that enter and leave the heart
cardiac muscle tissue
myocardium
In the ventricles, the myocardium is arranged into =
deep and superficial layers
what kind of course does the superficial layer of myocardium have around ventricle
spiral course
Deepr myocardium fibers have a
circular course
the outermost coat of epicardium is formed by
mesothelial cells
under the mesothelium of epicardium is
a subepicardial layer of loose CT and adipose tissue which contains coronary blood vessels and nerves
Fibrous skeleton of heart is composed of
dense irregular connective tissue
septum membranaceum
fibrous portion of the interventricular septum
Annuli fibrosi
fibrous rings around the origins of the pulmonary artery, aorta and AV canals
fibrous tissue between the arterial foramina and the AV canals
trigona fibrosa
annuli around AV orifices result in
electrical discontinuity between myocardial cells of atria and ventricles (controls communication between them via specialized conducting tissue (AV bundle)
SA node fires
action potentials spread through atria
AV node fires
impulses go along conducting fibers
Atrioventricular valves (names)
tricuspid and mitral
atrioventricular valves are connected to
papillary muscles of ventricles by fibrous cords called chordae tendineae
semilunar valves are between
ventricles and aorta and pulmonary trunk
valves have both dense and loose CT layers surrounded by
endothelium
pacemaker of the heart
SA node
sinoatrial node contains
modified cardiac muscle cells concentrically arranged around a nodal artery.
impulse spreads from SA node via
specialized conduction fibers to the AV node
AV lies beneath
the endocardium of the septal wall of the right atrium.
the AV bundle of His is formed by
Purkinje fibers(cardiac conduction fibers)
Purkinje fibers penetrate fibrous skeleton and then branch to form
right and left bundle branches
AV node continues to form a
common stem– the AV bundles of His. Controlling structures
Purkinje fibers are
modified muscle cells filled with glycogen
purkinje fibers travel in the subendocardial layer to the heart apex then
reverse direction and branch to make contact and form gap junctions with cardiac muscle cells
Parasympathetic nerves from vagus to SA node
slow the heart
Sympathetic nerves to heart
accelerate heartbeat
atrial cardiac muscle cells and some cells in the IV septum are the source of
polypeptide hormones (Cardiac endocrine cell)
ANP gene makes 4 different hormones :
a long acting natriuretic (sodium) peptide, vessel dilator, kaliuretic (potassium) peptide and ANP
Primary effect of this peptide is to increase sodium and H20 secretion from kidney
Atrial natriuretic peptide
atrial natriuretic peptide is released in response to
high blood pressure
The tunica media layer of muscular arteries contain up to
40 circular layers of smooth muscle interdispersed with elastic fibers
