CIRC Flashcards
pumpsanddirects blood cells and
substances carried in blood to all tissues
of the body
CIRCULATORYSYSTEM
Thebloodvascular system, or
cardiovascular system consists of the
following structures:
- HEART
- ARTERIES
- CAPILLARY
- VEINS
propels blood through
the system and is
surrounded by the
pericardium (a fibrous
sac lined by serous
mesothelium)
heart
a series of vessels
efferent from the heart
that become smaller as
they branch into the organs
arteries
, carry
blood to the tissues.
arteries
sites of O2 , CO2 ,
nutrient, and waste
product exchange
between blood and
tissues.
capilaries
complex
network of thin,
anastomosing tubules
microvasculature
makes microvasculature
Together with the
smallest arterial and
venous branches
carrying blood to and
from them, capillaries
in almost every organ
form it
result from the
convergence of venules
into a system of larger
channels which
continue enlarging as
they approach the heart,
veins
carry
the blood to be pumped
again.
vei
Twomajordivisions of arteries,
microvasculature, and veins
make up the
pulmonary circulation,
Twomajordivisions of arteries,
microvasculature, and veins
where blood is
oxygenated in the lungs,
pulmonary circulation,
systemic circulation
lood
brings nutrients and removes wastes in
tissues throughout the body.–
thin-walled, closed-ended
tubules carrying lymph that merge to
form vessels of steadily increasing size.
lymphatic capillaries
Theinternal surface of all components
of the blood and lymphatic systems is
lined
by a simple squamous epithelium
called endothelium.
functions of endothelium
○ Notonlymust endothelial cells
maintain a selectively
permeable, antithrombogenic
(inhibitory to clot formation)
barrier,
○ theyalso determine when and
where white blood cells leave
the circulation for the interstitial
space of tissues and-
○ secrete a variety of paracrine
factors for vessel dilation,
constriction, and growth of
adjacent cells
Cardiac muscle in the four chambers
RL ventricle
RL artery
propel
blood to the pulmonary circ
right ventricle
propel
blood to the circulatory circulation
left ventricle
receive blood from
the body
right atria
receive blood from
the pulmonary veins
left atria
3 major layers walls of the heart chamber
endocardium, myocardium, epicardium
endocardium made up of
- lining endothelium with supportive layer of fibroelastic ct with scattered fibers of smooth muscle
- deeper layer of ct called subendocardial layer, surrounding modified cardiac muscles
modified cardiac muscle fibers that
comprise the heart’s impulse conducting
system
-consists mainly of typically contractile
cardiac muscle fibers arranged spirally
around each heart chamber.
myocardium
- a simple squamous mesothelium
supported by a layer of loose connective
tissue containing blood vessels and
nerves.
epicardium
corresponds to the
visceral layer of the pericardium, the
membrane surrounding the heart
epicardium
Where the large vessels enter and leave
the heart
epicardium
separates the musculature of the atria
from that of the ventricles, forms part of
the interventricular and interatrial septa,
and extends into the valve cusps and the
chordae tendineae to which they are
attached `
cardiac skeleton
FUNCTION OF VARIOUS REGION OF
CARDIAC SKELETON
■ Surrounding, anchoring, and supporting all
heart valves
■ Providing firm points of insertion for cardiac
muscle in the atria and ventricles-
■ Helping coordinate the heartbeat by acting as electrical insulation between atria and ventricles.
CONDUCTINGSYSTEMOFTHE
HEART ahppens at
subendocardial layer
what makes CONDUCTING SYSTEM OF THE
HEART
adjacent myocardium, modified cardiac
muscle cells make up this impulse.
specialized to generate and conduct
waves of depolarization,which stimulate rhythmic contractions in adjacent myocardial fibers.
CONDUCTINGSYSTEMOFTHE
HEART
⑥
consists of two nodes of specialized
myocardial tissue in the right atrial wall
CONDUCTINGSYSTEMOFTHE
HEART
two nodes of specialized
myocardial tissue in the right atrial wall
SA and AV
STRUCTURE OF SINOATRIAL NODE
a 6- to 7-mm3 region of less
well-stained cardiac muscle cells with
smaller size.
fewer myofibrils, and fewer typical
intercalated disks than the neighboring
contractile fibers.
LOCATION OF SA
RIGHT ATRIAL WALL NEAAR SUPERIOR VENA CAVA
move along myocardial fibers of
both atria stimulating contraction
SA NODE
AV NODE LOCATION
⑧
their
located in the floor of the right atrium
near the AV valve
stimulate depolarization myocytes
there.
AV NODE
bifurcates into left and right bundles of
myocyte
CONDUCTING MYOCYTES GROUPED INTO AV BUNDLES
purkinje fiber location
apex of the heart
bundles subdivide further into a
subendocardial conducting network of
cardiac muscle fibers.
pale-staining fibers
purkinje fiber
purkinje
pale-staining fibers, larger than the
adjacent contractile fibers, with sparse,peripheral
glycogen.
innervate the heart.
Both
sympathetic
innervate the heart.
parasympathetic
neural
and
components
affect heart rate and rhythm, such as
during physical exercise and emotional
stress.
Ganglionic nerve cells and nerve
fibers
slows the
heartbeat,
Stimulation of the parasympathetic
division (vagus nerve)
stimulation of the
sympathetic nerve
accelerates activity of
the pacemaker.
angina pectoris
Between fibers of the
myocardium are afferent free nerve
endings that register pain, such as the
discomfort
occurs when partially occluded coronary
arteries cause local oxygen deprivation.
angina pectoris
Walls of all blood vessels except
?contain ?? in addition to the
.??
Walls of all blood vessels except
capillaries contain smooth muscle and
connective tissue in addition to the
endothelial lining.
endothelium is a barrier between
acts as a
semipermeable barrier between two
major internal compartments: the blood
and the interstitial tissue fluid.
with its basal lamina is highly
differentiated to mediate and actively
monitor the bidirectional exchange of
molecules by simple and active
diffusion,
O
receptor-mediated
endocytosis, transcytosis, and other
mechanisms.
Endothelium
Vascular endothelial cells
squamous, polygonal, and elongated
with the long axis in the direction of
blood flow.
secretes various
factors that stimulate smooth muscle
contraction (such as endothelin-1 and
angiotensinconverting enzyme [ACE])
or relaxation (including nitric oxide
[NO] and prostacyclin).
endothelium
is expressed
rapidly on the luminal surface when
unique elongated granules, called
Weibel–Palade bodies, fuse with the
cell membrane.
p-selectin
when wbc is undergoing transendothelial migration
at sites of injury or infection, what is expressed
rapidly o
undergo transendothelial migration
at sites of injury or infection. Under
those conditions, P-selectin is expressed
rapidly oelectin
unique elongated granules, called
that fuse with the
cell membrane.
unique elongated granules, called
Weibel–Palade bodies, fuse with the
cell membrane.
stimulate formation of the vascular
system from embryonic mesenchyme
VEGF (vascular endothelial growth
factor
help maintain the vasculature in adults,
and promote capillary sprouting and
outgrowth from small existing vessels
angiogenesis
stimulate endothelial
cells to recruit smooth muscle cells and
fibroblasts to form the other tissues of
the vascular wall.
angiopoietins
In arterioles and small arteries, the
smooth muscle cells are
connected by
many more gap junctions and permit
vasoconstriction and vasodilation that
are of key importance in regulating the
overall blood pressure.
collagen location
found in the
subendothelial layer, between the smooth muscle
layers, and in the outer covering.
provide the resiliency required
for the vascular wall to expand under pressure.
elastic fiber
major component in large arteries
where it forms parallel lamellae, regularly
distributed between the muscle layers.
elastin
composition
of ground substance, contribute to the physical
and metabolic properties of the wall in different
vessels, especially affecting their permeability
Proteoglycans and Hyaluronate
tunica intima consists of
consists of the endothelium and a thin
subendothelial layer of loose connective
tissue sometimes containing smooth
muscle fibers
layer that shows folds in cross sections
tunica intima
tuni intima often shows folds
in cross section as a result of the loss of
ften shows folds
in cross section as a result of the loss ofblood pressure and contraction of the
vessel at death
Between the intima
and the media, which is more well-defined than
the elastic laminae of the media.
internal elastic lamina
consists chiefly of concentric layers of
helically arranged smooth muscle cells
tunica media
In arteries, the media may also have an
??? ??? it from
the outermost tunic.
In arteries, the media may also have an
external elastic lamina separating it from
the outermost tunic.
Interposed among the muscle fibers are
variable amounts of elastic fibers and
elastic lamellae, reticular fibers, and
proteoglycans, all of which are produced
by the
smooth muscle cells.
STRUCTURE OF TUNICA ADVENTITIA
connective tissue consisting principally
of type I collagen and elastic fibers.–
continuous with and bound to the stroma
of the organ through which the blood
vessel runs.
release the vasoconstrictor
norepinephrine.
VASOMOTOR NERVE
-
&
On larger vessels this also contains a
network of unmyelinated autonomic
nerve fibers, the vasomotor nerve
-
&
On larger vessels this also contains a
network of unmyelinated autonomic
nerve fibers, the vasomotor nerve
he density of this
innervation is greater in ?? than in
?/.
he density of this
innervation is greater in arteries than in
veins.
vessels of the vessel.
VASO VASORUM
required to provide metabolites to cells
in those tunics in larger vessels because
the wall is too thick to be nourished
solely by diffusion from the blood in the
lumen.
VASOVASORUM
provide the
needs of cells in the intima. Because
they carry deoxygenated blood, large
veins commonly have more vasa
vasorum than arteries.
LUMINAL BLOOD
Large blood vessels and those of the
microvasculature branch frequently and
undergo
gradual
transitions
into
structures with different histologic
features and functions.
VASCULATURE
major role is to
carry blood to smaller arteries
CONDUCTIN/ELASTIC ARTERY
are the aorta, the pulmonary artery, and
their largest branches; these large
vessels are also called
conducting/ELASTIC
arteries
most prominent feature of elastic
arteries
thick tunica media which elastic lamellae alternate with
layers of smooth muscle fibers.
numerous elastic lamellae of elastic artery helps in
makning blood flow uniformly
blood is moved through
the arteries forcefully and the elastin is
stretched, distending the wall within the limit set
by the wall’s collagen.
ventricular
contraction (systole)
diastole
ventricular pressure drops to a low level, but the
elastin rebounds passively, helping to maintain
arterial pressure
prevent backflow of blood into the heart
aortic and pulmonary valce
decrease and become less variable as
the distance from the heart increases.
arterial blood perssure and velovity
slight dilations of the bilateral internal
carotid arteries where they branch from
the (elastic) common carotid arteries.
carotid sinus
act as important baroreceptors
monitoring arterial blood pressure.
carotid sinus
Histologically, more complex ???
that monitor blood CO2 and O2 levels, as well
as its pH, are found in the ???? and in
the??? , located in the walls of the
? ? respectively.
Histologically, more complex chemoreceptors
that monitor blood CO2 and O2 levels, as well
as its pH, are found in the carotid bodies and in
the aortic bodies, located in the walls of the
carotid sinuses and aortic arch, respectively.
large, neural crest-derived.
glomuss cell
glomus cells are filled and contained with
O
with
dense-core
vesicles
containing dopamine, acetylcholine, and
other neurotransmitters, which are
supported by smaller satellite cells
on channels in the????? respond to stimuli in the
arterial blood, primarily hypoxia (low
O2 ), hypercapnia (excess CO2 ), or
acidosis, by activating release of
neurotransmitters.
glomus cellmembranes
also called distributing arteries.
muscular arteries
distribute blood to the organs and help
regulate blood pressure by contracting
or relaxing the smooth muscle in the
media.
muscular artery
structure of muscular artery
The intima has a thin subendothelial
layer and a prominent internal elastic
lamina.
The media may contain up to 40 layers
of
Iel
large
smooth
muscle
cells
interspersed with a variable number of
elastic lamellae (depending on the size
of the vessel).—e
An external elastic lamina is present
only in the larger muscular arteries. The
adventitial connective tissue contains
lymphatic capillaries, vasa vasorum, and
nerves, all of which may penetrate to the
outer part of the media
Muscular arteries branch repeatedly into
smaller and smaller arteries, until
.
reaching a size with three or four layers
of medial smooth muscle
smallest artery
muscular artery
ndicate the beginning of
an organ’s microvasculature where
exchanges between blood and tissue
fluid occur.
muscular artery having 1 or 2 layer which is the usual
lumens approximately as wide as
the wall is thick.
muscular artery
branch to form
anastomosing networks of capillaries
that surround the parenchymal cells of
the organ.
muscular atrery
At the ends of arterioles-Act as sphincters and produce
periodic blood flow into capillaries
-
.
Smooth muscle fibers-
keeps
arterioles
partially
closed,
resisting blood flow, which makes these
vessels the major determinants of
systemic blood pressure
muscle tone
control
the degree of vasoconstriction at
the shunts, regulating blood
flow through the capillary beds.
AUTONOMIC FIBERS
blood flows through two
successive
capillary
separated by a portal vein
venous portal system,
Lacks media and adventita tunics
CAPILLARIES
allows transit of
blood cells only one at a time,
CAPILLARIES
make up over 90% of the body’s
vasculature, w
CAPILLARIES
can be recognized by
nuclei adjacent to small lumens or by
highly eosinophilic red blood cells in the
lumen.
Paraffin sections
nuclei are often distinctively curved to
accommodate the very small tubular
structure
capillaries
maintain
the tubular structure, with variable
numbers of tight junctions having an
important role in capil lary permeability.
Capillaries
permit
and
regulate
Along with the basal lamina, junctional
complexes between the cells
permit
and
regulate
metabolic exchange between blood and
surrounding tissue
capillaries
These smallest
blood vessels
always function in
networks calle
capillary beds
types of capillaries
- continuous
2.fenestrated - disontinuous
Most common capillary type
Continuous capillaries
have
many tight,
well-developed occluding
junctions
between
slightly
overlapping endothelial cells
continuois capillaryq
provide for continuity
along the endothelium and
well-regulated
metabolic
exchange across the cells
continuous cpaillary
continuous capillary loc
O
found in muscle, con nective
tissue, lungs, exocrine glands,
and nervous tissue.
MuConLuExNe
exert the
tightest
control over what
molecules leave and enter the
capillary lumen
continuous capillary
have a sieve-like structure that
allows
more-
extensive
molecular exchange across the
endothelium
fenestrated capillary
structure of fesnestrated capillary
Some fenestrations are covered
by very thin diaphragms of
proteoglycan.The
②
basement
membrane
however
is
continuous and covers the
fenestrations
location of fenestrated capillary
in organs with rapid inter
change of substances between
tissues and the blood, such as
the kidneys, intestine, choroid
plexus, and endocrine glands.
kiInChoEn
AKA sinusoids
discontinuous capillaries
permit maximal exchange of
macromolecules as well as
allow easier movement of cells
between tissues and blood
discontnuous capillary/sinusoids
have
highly
basement
membranes and much larger
diameters, often 30-40 μm,
which slows blood flow
sinusoids
sinusoids location
O
e found in the liver, spleen,
some endocrine organs, and
bone marrow
LiSpleEnBo
At various locations along continuous
capillaries and postcapillary venules are
mesenchymal cells called
pericytes
ecrete many ECM components and
form their own basal lamina fuses with the basement membrane of
the endothelial cell
pericytes
dilate or constrict
capillaries, helping to regulate blood
flow in some organ
pericytes
maintaining
the
endothelial
blood-brain barrier. in CNS
Pericytes
proliferate and
differentiate to form smooth muscle
pericytes
The density of the capillary bed is
related to the ??? of the
tissues.
The density of the capillary bed is
related to the metabolic activity of the
tissues.
tissue with low metabolic rates,
such as smooth muscle and dense
connective tissue
Capillary
beds
are
supplied
preferentially by one or more terminal
arteriole branches called ,
metarterioles
capillary beds are continuous with thoroughfare
channels
connected with the
postcapillary venules
The ???? act as ???? that control blood flow into
the capillaries
The metarteriole
muscle cells act as precapillary
sphincters that control blood flow into
the capillaries.T
.These sphinc ters contract
and relax cyclically, causing blood to pass
through capillaries in a pul satile
manner
precapillary
sphincters
When the sphincters are closed,
blood flows directly from
metarterioles
capillary beds are composed of
Composed o simple layer of endothelial
cells rolled up as a tube surrounded by
basement membrane
not all interstitial fluid formed at
capillary beds is drained into venules;
the excess is called
lymph
lymph collects
in thin-walled, irregularly shaped
lym
phatic vessels (L),
lymphatic vessels are see in
connective tissue and smooth muscle
imilar to
capillar ies with pericytes but larger,
Postcapillary venules
characteristic feature of all venules is
the large diameter of the lumen
compared to the overall thin ness of the
wall (
primary site at which white blood cells
adhere to endothelium and leave the
circulation at sites of infection or tissue
damage.
post capillary venules
Blood entering veins is under very low
pres sure and moves toward the heart by
contraction of the smooth muscle fibers
in-
the
media and by external
compressions from surrounding skeletal
muscles and other organs
location of vein
close and parallel to
corresponding muscular arteries
directly connect the arterial and venous
systems
and
temporarily
capillaries.
av shunts//anastosomes
In skin, blood flow can be varied
according to external condi tions by
,
arteriovenous
(AV)
shunts,
or
anastomoses
col lect excess
interstitial fluid from the tissue spaces as
lymph and return it to the blood.
lymphatic
capillaries
sually rich in lightly staining proteins
but does not normally contain red blood
cells, although lymphocytes and other
white blood cells may normally be
present
LYMPH
Except ??? and ???? , most tissues with blood micro
vasculature also contain lymphatic
capillaries (or lymphatics)
Except bone marrow and most of the
CNS, most tissues with blood micro
vasculature also contain lymphatic
capillaries (or lymphatics)
originate locally as tubes of very thin
endothelial cells, which lack tight
junctions and rest on a discontinuous
basal lamina.
lymphatic capillaries
interstitial fluid enters capillaries VIA
entering lymphatic capillaries by flowing
between
endothelial cells and by transcytosis.
lack
hemidesmosome connections to the
basal lamina and extend into the lumen
to form leaflets of valves facilitating
fluid
>–
entry and preventing most
backflow of lymph
Specific
domains of adja cent
endothelial
cells
larger lymphatic vessels
are lymph
nodes
lymphat8ic capillaries ultimately converge as two large trunks:
thoracic duct and the right
lymphatic duct,
empty lymph
back into the blood
vright
lymphatic duct,
⑳
connects with the blood circulatory
system near the junction of the lefinternal jugular vein with the left sub
clavian vein,
thoracic duct
②
enters near the confluence of the right
subclavian vein and the right internal
jugular vein.
right lymphatic duct
major distributor of lymphocytes,
antibodies, and other immune components that
are carried through many organs to and from
lymph nodes and other lymphoid tissues
lymphatic vascular
system
where lymph is processed by cells of the
immune system
lymph nodes
