Histo Circulation book based Flashcards
propels blood through the system and is
surrounded by the pericardium
HEART
a fibrous sac lined by
serous mesothelium.
pericardium
a series of vessels efferent from the heart that
become smaller as they branch into the various organs, carry blood to the tissues.
Arteries
the smallest vessels, are the sites of O2 , CO2 nutrient, and waste product exchange between blood and tissues
Capillaries
capillaries in almost every organ form a complex network of thin, anastomosing tubules called the _________________________
microvasculature
result from the convergence of venules into a system of larger channels which continue enlarging as they
approach the heart, toward which they carry the blood to be pumped again.
Veins
two major divisions of arteries,
microvasculature, and veins make up the ______________________, where blood is oxygenated in the lungs, and the ___________________, where blood brings nutrients and removes
wastes in tissues throughout the body.
pulmonary circulation, systemic circulation,
thin-walled, closed-ended tubules carrying lymph that merge to form vessels of steadily increasing size
lymphatic capillaries
The internal surface of all components of the blood and lymphatic systems is lined by a simple squamous epithelium called ______________
endothelium
propel blood to the pulmonary and systemic circulations
ventricles
receive blood from the body and
the pulmonary veins, respectively
atria
consists of the lining endothelium, its supporting layer of fibroelastic connective tissue with scattered fibers of smooth muscle, and a deeper layer of connective tissue
endocardium
consists mainly of typically contractile cardiac muscle fibers arranged spirally around each heart chamber
myocardium
Because strong force is required to pump blood through the systemic and pulmonary circulations, the _______________ is much thicker in the walls of the ventricles than the atria
myocardium
the wall of the ______________ is about ________________ than that of the right ventricle because the left side must produce sufficient force to propel blood through the much larger systemic circulation with its multiple capillary beds
left ventricle, three times thicker
is a simple squamous mesothelium
supported by a layer of loose connective tissue containing blood vessels and nerves
epicardium
The epicardium corresponds to the ______________________, the membrane surrounding the heart.
visceral layer of the pericardium
These are pale-staining
fibers, larger than the adjacent contractile fibers, with sparse, peripheral myofibrils, and much glycogen
Purkinje fibers
is a specialized epithelium that acts as a semipermeable barrier between two major internal compartments: the blood and the interstitial tissue fluid.
endothelium
The endothelium presents a _______________________
on which blood will not clot and actively secretes agents that control local clot formation
nonthrombogenic surface
occur in the walls of all vessels
larger than capillaries and are arranged helically in layers
Smooth muscle fibers
are found in the
subendothelial layer, between the smooth muscle layers, and
in the outer covering
Collagen fibers
consists of the endothelium and a thin subendothelial layer of loose connective tissue sometimes containing smooth muscle fibers
tunica intima
consists chiefly of
concentric layers of helically arranged smooth muscle
cells
tunica media
is connective tissue consisting principally of type I collagen and elastic fibers
tunica adventitia
Just as the heart wall is supplied with its own coronary vasculature for nutrients and O2
, large vessels usually have __________________________
vasa vasorum
are 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
vasa vasorum
these include the aorta, the pulmonary artery, and their largest branches
ELASTIC ARTERIES
are slight dilations of the bilateral internal
carotid arteries where they branch from the (elastic) common carotid arteries
Carotid sinuses
monitoring arterial blood pressure
baroreceptors
monitor blood CO2 and O2 levels, as well as its pH
chemoreceptors
distribute blood to the organs and help regulate blood pressure by contracting or relaxing the smooth muscle in the media
Muscular Arteries
Conduct blood
from heart and
with elastic recoil
help move blood
forward under
steady pressure
Elastic arteries
Distribute blood
to all organs and
maintain steady
blood pressure
and flow with
vasodilation and
constriction
Muscular arteries
Distribute blood
to arterioles,
adjusting flow with
vasodilation and
constriction
Small arteries
Resist and control
blood flow to
capillaries; major
determinant of
systemic blood
pressure
Arterioles
Exchange
metabolites by
diffusion to and
from cells
Capillaries
Drain capillary
beds; site of
leukocyte exit from
vasculature
Venules
Collect blood from
venules
Small veins
Carry blood to
larger veins, with
no backflow
Medium veins
Return blood to
heart
Large veins
permit and regulate metabolic exchange between
blood and surrounding tissues.
Capillaries
network of Capillaries
capillary beds
have many tight, well-developed occluding junctions between slightly overlapping endothelial cells, which provide for continuity along the endothelium and well-regulated metabolic exchange across the cells.
Continuous capillaries
This is the most common type of capillary and is found in muscle, connective tissue, lungs, exocrine glands, and nervous tissue.
Continuous capillaries
have a sieve-like structure that allows more extensive molecular exchange across the endothelium
Fenestrated capillaries
permit maximal exchange of macromolecules as well as allow easier movement of cells between tissues and blood
Discontinuous capillaries, commonly called sinusoids
At various locations along continuous capillaries and
postcapillary venules are mesenchymal cells called
pericytes
are the primary site at which white blood cells adhere
to endothelium and leave the circulation at sites of infection or tissue damage.
Venules
carry blood back to the heart from microvasculature
all over the body
Veins
Most veins
are classified as _____________________
small or medium veins
The big venous trunks, paired with elastic arteries close to the heart, are the _______________
large veins
consist of thin, paired folds of the tunica intima
projecting across the lumen, rich in elastic fibers and covered on both sides by endothelium
valves
excess interstitial fluid from the tissue spaces
lymph
connects with the blood circulatory system near the junction of the left internal jugular vein with the left subclavian vein
thoracic duct
enters near the confluence of the right subclavian vein and the right internal jugular vein
right lymphatic duct
located in the subendocardial layer of both ventricles, are distinguished from contractile fibers by their greater diameter, abundant glycogen, and more sparse bundles of myofibrils
Purkinje fibers
separates the atria from the ventricles, and provides insertions for cardiac muscle.
cardiac skeleton
includes the endothelium, connective tissue, and an internal elastic lamina in larger vessels;
tunica intima
contains alternating layers of smooth muscle and collagen or elastic lamellae
tunica media
contains connective tissue, small vessels
tunica adventitia
