Vascular System Pt 1 Flashcards
Primary function of cardiovascular system
Transport of O2/CO2 and nutrients/metabolic waste
Secondary function of cardiovascular system
thermoregulation; transport of immune cells/hormones (to tissues)
Vascular system consists of:
heart & blood vessels–arteries, capillaries, veins (blood vascular system)
2 components of circulatory system:
pulmonary circulation & systematic circulation
Route of Pulmonary circulation
RA & V -> pulmonary Aa-> lungs -> pulmonary Vv–> LA
Route of systematic circulation:
LA & V –> aorta –> rest of body
passive drainage system for returning blood extravascular fluid to blood vascular system
Lymph vascular system (extravascular fluid is lymph)
Lymph vascular system lacks ____, relies on _____, body movement, passive fluid transport by surrounding tissues
intrinsic pump; Muscle contraction
folded epithelia tube with walls thickened to act as a regulated pump
heart
3 layers of the cardiac wall:
endocardium, myocardium, epicardium
(Heart Layer) consisting of an
endothelial lining and subendothelial
connective tissue
endocardium
(Heart Layer) a functional syncytium of
striated cardiac muscle fibers forming
three major types of cardiac muscle:
atrial muscle, ventricular muscle, and
specialized excitatory and conductive
muscle fibers.
myocardium
Myocardium: a functional syncytium of
striated cardiac muscle fibers forming
three major types of cardiac muscle:
atrial muscle, ventricular muscle, and
specialized excitatory and conductive
muscle fibers.
(Heart layer) the visceral layer of the
pericardium, is a low-friction surface
lined by a mesothelium in contact with
the parietal pericardial space.
epicardium
The ___ is lined by
endothelium with underlying
layers of CT, a middle layer of
smooth muscle and an elastic
CT, and a subendocardial
layer that is connected to the
myocardium
endocardium
The
subendocardial layer contains
modified cardiac muscle cells
(e.g._______) of the
heart’s impulse conducting
system.
Purkinje fibers
where are Purkinje fibers found?
subendocardial layer (endocardium)
Is the thickness of the CT layers in the endocardium consistent?
no
The _____ is the
thickest layer of the heart
wall
myocardium
The myocardium is the
thickest layer of the heart
wall and contains ___
muscle, ____ tissue,
and ____
cardiac muscle, connective tissue, and small blood vessels
The myocardium is thicker in the ___ compared to the atria
ventricles
The epicardium is
lined by ______
with an underlying layer
of loose CT that is rich
in ____ tissue and
contains small nerves
and blood vessels
(vasa vasorum) as well
as the large coronary
vessels
mesothelium. adipose
Visceral pericardium is also known as the _____
epicardium
outermost layer of the blood vessel
wall
Tunica Externa/Adventitia
composed of a loose CT that contains
elastic and collagen fibers
– helps anchor the vessel to other
tissues
– An external elastic lamina can be seen
separating the tunica media from the
adventitia.
– vasa vasorum
Tunica Externa/adventitia
middle layer of the vessel wall
– composed of circularly arranged
layers of smooth muscle cells
Tunica Media
innermost layer of a blood vessel wall
– composed of an endothelium and a
subendothelial layer
Tunica Intima/Interna
Tunica Intima has an external layer of elastic fibers, called the
_____
internal elastic lamina
Blood vessels of circulatory
system have common basic
structure with three
concentric layers called
tunics
innermost layer of
simple squamous endothelial
cells lining lumen
Very thin layer, 1-2 cells thick
Forms semi-permeable barrier,
supported by basement
membrane
Tunica Intima
Tunica Intima have: Specialized discontinuous tight
junctions between endothelial
cells called ______
Fascia Occludens
if present,
separates tunica intima &
media
Internal Elastic Lamina
Internal elastic lamina is composed of ____ fibers
elastic
–highly variable middle layer
–Smooth Mm cells &
fibroblastic connective tissue
–In Aa, thickest of layers; may
also contain reticulin (type III
collagen) & elastic fibers
Tunica media—
if present,
located between tunica media
& adventitia
* Also composed of _____
fibers, but less organized than
internal elastic lamina
External Elastic Lamina; elastic
–Consists of loose fibroblastic
connective tissue—
–Fibroblasts, collagen & elastic
fibers, smooth Mm cells
–outermost layer
Tunica Adventitia
In veins, what is the thickest tunic layer?
In arteries?
Tunica adventitia in veins. Tunia Media in arteries.
In larger vessels, Tunica Adventitia contains ____
vasa vasorum
Small blood vessels that supply
the tunica media & adventitia in
both large Aa & Vv
vasa vasorum
Tunica Adventitia also contains autonomic Nn,
___________—
nervi vasculares
(Tunica Adventitia) Control smooth Mm contraction
in vessel walls (vasoconstriction &
vasodilation)
nervi vasculares
Vasoconstriction of blood vessels due to action of
________ nerve fibers
sympathetic, post-ganglionic nerve fibers
Vasoconstriction acts on smooth Mm of _______
tunica media
Vasoconstriction acts on smooth Mm of tunica media, cause constriction &
___ in lumen diameter
↓ decrease
Vasodilation is ____; occurs in absence or inhibition of sympathetic
stimulation
passive
Vasodilation accomplished via indirect parasympathetic innervation
–Ach causes endothelial cells to release __________, which 2’
causes smooth Mm cells to relax
nitrous oxide (NO)
In response to low O2 tension, smooth Mm in walls of arterioles
_____—results in vasodilation & ↑ blood flow
relaxes
In response to low O2 tension, smooth Mm in walls of arterioles
relaxes—results in:
vasodilation & ↑ blood flow
specialized sensory receptors located in carotid sinus & aortic
arch; detect blood pressure
Baroreceptors
specialized sensory receptors located at bifurcation of carotid
Aa & in aortic bodies in aortic arch; Detect changes in O2, CO2 tension & pH
chemoreceptors
Arteries conduct blood from the heart to the
____
capillaries
arteries store some of the pumped blood during
each cardiac _____ to ensure continued flow
through the capillaries during cardiac ____
systole; diastole
Arteries are organized in three major tunics or
layers:
Tunica intima, tunica media, tunica
externa
Arteries contain large amounts of ____ &
_____ Mm; vessel wall thick relative to lumen diameter
elastin. smooth.
T/F: Artery vessel wall thin relative to lumen diameter
False–vessel wall thick relative to lumen diameter
from the heart to the
capillaries, arteries can be
classified into three major
groups
–large elastic arteries
–medium-sized muscular
arteries
–small arteries and
arterioles.
more than 1 cm in diameter—large
conducting vessels, receive blood
directly from heart
elastic arteries
Have sheets of elastic tissue in
tunica media; helps maintain bp
between systole & diastole
elastic arteries
Thickest layer of elastic arteries
tunica media
elastic arteries posses both internal and external ____ layers
elastic
Two major characteristics: (1) They receive blood from the
heart under high pressure. (2) They keep blood circulating
continuously while the heart is pumping intermittently
Large elastic (conducting) arteries
Distend during systole and recoil during diastole
Large elastic (conducting) arteries
(large elastic–conducting–arteries) Large amounts of fenestrated elastic sheaths are found in
the ______ of the large elastic arteries, with bundles of smooth muscle cells
permeating the narrow gaps between the elastic lamellae
tunica media
Blood vessels (vasa vasorum), nerves (nervi vasorum), and
lymphatics can be recognized in the _______ of
large elastic arteries
tunica adventitia
~2-10 mm in diameter—
medium-sized distributing
Aa
* Have more smooth Mm &
less elastin in tunica media
than elastic Aa
muscular arteries
In muscular arteries ___ is the thickest layer
tunica media
muscular arteries have a distinct _____; larger muscular Aa
may also contain external
elastic lamina
internal elastic
lamina
Allow a selective distribution of
blood to different organs in
response to functional needs.
Diameter about 2-3 mm or
greater
muscular or distributing arteries
Tunica intima of distributing arteries consists of three
layers:
(1) the endothelium, (2)
the subendothelium, and (3) the
internal elastic lamina (IEL
Distributing Arteries: in the larger vessels of this group,
a fenestrated external elastic
lamina can be seen at the junction
of the ___
tunica media and the
adventitia.
Distributing Arteries: The tunica media
shows a significant
reduction in _____ and an
increase in smooth muscle fibers
elastic
components
the radial, tibial,
splenic, mesenteric,
and intercostal
arteries are examples of
medium-sized arteries
Final branches of the arterial
system
Arterioles or Resistance Vessels
Resistance Vessels: Final branches of the arterial
system
* ~10-100 m in diameter—contain
relatively little ____ (tunica
media only ~2-3 cells thick)
smooth Mm
–Regulate the distribution of blood
to different capillary beds by
vasoconstriction/vasodilation
–the major determinants of systemic blood pressure
Arterioles
(types of arteries)
–Structural adaption is walls with
circularly arranged smooth muscle
–Partial contraction of the vascular smooth
muscle exists here
arterioles
Partial contraction also known as
tone
Regulate distribution of blood to
capillaries via pre-capillary
sphincters, intermittent rings of
smooth M within walls of
arterioles
Arterioles
Arterioles regulate distribution of blood to capillaries via ___, intermittent rings of
smooth M within walls of
arterioles
pre-capillary
sphincters
–small
diameter arterioles;
intermediate in size
between arterioles &
capillaries
–regulate blood leaving the arteries
metarterioles
metarterioles: Characterized by
_____ layer of
smooth Mm in tunica
media
discontinuous
Arteries: In general, amount of
smooth Mm ↑ with ___
diameter of vessel (&
relative amount of
connective tissue ↓)
↑ increase
The microvascular bed is
composed of the ____ (and metarteriole), the
capillary bed, and the
postcapillary venules
terminal
arteriole
the site
of the microcirculation
microvascular bed
The capillary bed consists of
slightly large capillaries called ______ where bloodflow is continuous
preferential or thoroughfare
channels
preferential or thoroughfare
channels: blood flow here is ___
continous
true capillaries: small capillaries, blood flow here is ______
intermittent
The functional units of the
cardiovascular system
capillaries (where work gets done)
–Smallest blood vessels, connect
arterioles to venules
–Concerned with exchange of gases,
fluids, nutrients, metabolites, & waste
products
capillaries
The diameter range of a capillary is
about 5 to 10 μm, large enough to
accommodate one ___ cell, and
thin enough for _____
red blood. gas diffusion.
Capillaries: Contain only the tunica _____, but this
layer consists of a basement membrane
and endothelium only, small #
pericytes.
intima
group of capillaries (10–
100) functions together
capillary bed
(capillaries) Pericytes derived from same precursor cell as ____
endothelial cells
(capillaries) _____ can differentiate into endothelial cells or smooth Mm cells
following injury
pericytes
Capillaries lack outer connective tissue layer (no tunica
______)
adventitia
Capillaries also lack smooth Mm (no tunica ___)
media
Do not exhibit vasomotor activity themselves
capillaries
Vasodilation & vasoconstriction of capillaries accomplished via smooth muscle contraction in arterioles & ________ => passive change in capillary diameter
pre-capillary sphincters
3 basic types of capillaries:
Continous, Fenestrated, Sinusoid
capillaries lined by endothelium w/tight junctions
and a basal lamina w/pericytes
continous
capillaries with pores or fenestrae (GI & kidney
fenstrated
________ are characterized by
an incomplete endothelial lining and basal lamina, with gaps
or holes between and within endothelial cells (liver & spleen)
sinusoids (or discontinuous capillaries)
Intracellular cleft present on what type of capillary
Continuous capillaries
