Anatomy Bone Marrow & Blood Cell Formation
Blood cells all originate from what type of cells, that continually divide?
stem cells
What is the thin layer covering the tunica intima in vessels over about 1 mm in diameter, and what is it composed of?
subendothelial layer loose connective tissue
What vessel carries blood returning to the heart from the head/upper body?
superior vena cava
What is the "vessels of vessels" that nourish the outer region of large vessels, found in the tunica externa?
vasa vasorum
What do vessels interconnect to form?
vascular anastomoses
Venules join to form what?
veins
What is the dormant marrow?
yellow
What are the four routes into and out of capillaries (routes of capillary permeability)?
direct diffusion intercellular clefts fenestrations cytoplasmic vesicles
The aorta and its major branches are what types of arteries? Sometimes called conducting arteries.
elastic
What are the largest arteries, with diameters ranging from 2.5-1 cm?
elastic
What are the three types of arteries?
elastic muscular arterioles
Elastic arteries have a high content of what substance in the tunica media, which stores media for continuous flow of blood?
elastin
Which two tissues lack capillary beds (are avascular)?
epithelia cartilage
What are six tissues that lack or have sparse capillary beds?
epithelia cartilage cornea lens tendons ligaments
What occurs in sinusoids?
exchange of large substances (proteins and whole cells)
What does yellow marrow mostly contain?
fat cells
What type of capillary has openings in endothelial cell membranes (fenestrae)?
fenestrated
What is the process by which blood vessels are formed (all originate in the bone marrow)?
hematopoiesis
What is the most undifferentiated blood stem cell?
hemopoietic stem cells
What vessel carries blood returning to the heart from the lower body?
inferior vena cava
Gaps of unjoined membrane between tight junctions, that overlap, in capillaries, are called what?
intercellular clefts
What are "wide open" in sinusoids?
intercellular clefts
What are the unique features of muscular arteries?
internal and external elastic laminae
What is the site-specific function of capillaries in the lungs?
oxygen enters blood, CO2 leaves
What are the supporting cells of capillaries?
pericytes
What is the function of capillaries in endocrine glands?
pick up hormones
What is the process of capillary permeability used by cytoplasmic vesicles?
pinocytosis
What do megakaryocytes break apart into?
platelets
What are the smallest venules?
postcapillary venules
What are the bands of smooth muscle that regulate the flow of blood to tissues in capillary beds?
precapillary sphincters
What are erythrocytes formed from?
proerythroblasts
Where does red marrow remain in the adult body?
proximal epiphyses girdles axial skeleton
What is the function of capillaries in the small intestines?
receive digested nutrients
Most bones in infants and children contain what type of marrow?
red
What structure actively generates new blood cells?
red marrow
What is the function of capillaries in kidneys?
removal of nitrogenous wastes
What two structures form the tissue framework for red marrow?
reticular connective tissue blood sinusoids
What structure in the tissue framework of red marrow support developing blood cells?
reticular connective tissue and reticular fibers
Capillaries are made up of what type of cells?
simple squamous endothelial cells
What are the wide, leaky capillaries found in some organs (usually fenestrated)?
sinusoids
Which capillaries have a large diameter and a twisted course?
sinusoids
What substance does the tunica media of arterioles contain?
smooth muscle
When _____________ of capillary beds are closed, blood does not pass through the true capillaries and bypasses inactive tissues.
sphincters
Which tissues are poorly vascularized, and receive nutrients from nearby connective tissue?
tendons ligaments
What is the single layer of endothelial cells in capillaries held together by?
tight junctions desmosomes
What is the thickest tunic in veins?
tunica externa
What portion of large vessels have tiny arteries, capillaries, and veins?
tunica externa
What is the outermost layer of blood vessels, and what is it composed of?
tunica externa (adventitia) dense connective tissue
What is the only layer of vessel found in capillaries?
tunica intima
What is the innermost layer of blood vessels, and what is it composed of?
tunica intima simple squamous epithelium
What are the three layers of blood vessels?
tunica intima tunica media tunica externa (adventitia)
What is the middle layer of a blood vessel, and what is it composed of?
tunica media sheets of smooth muscle, collagen, and elastin (especially in larger vessels)
In arterioles, contraction of smooth muscle causes ___________________ (smaller diameter), and relaxation causes ___________________ (larger diameter).
vasoconstriction vasodilation
What vessels carry blood toward the heart?
veins
What vessels have thinner walls?
veins
Which anastomose more frequently--veins or arteries?
veins
Which vessels have a larger lumen to vessel size ratio?
veins
Which vessels have thicker tunica externa (adventitia)?
veins
What are the smallest veins called, with diameters from 8-100 micrometers?
venules
Where do tendons and ligaments receive nutrients?
nearby connective tissues
What are two mechanisms to counteract low venous pressure?
one-way valves skeletal muscle pump
What do myeloid stem cells give rise to?
all other blood cells (other than lymphocytes)
What are the four "great vessels" of circulation?
aorta (and its major branches) pulmonary trunk (& pulmonary arteries & veins) inferior vena cava superior vena cava
Where do the cornea & lens of eye get their nutrients, since they are avascular (have no capillary beds)?
aqueous humor
What blood vessels carry blood away from the heart?
arteries
Which vessels have a smaller lumen to vessel size ratio?
arteries
Which vessels have a thicker tunica media?
arteries
Which vessels have more smooth muscle and/or elastin?
arteries
In which artery can the diameter of the lumen change?
arterioles
What are the smallest arteries?
arterioles
Neighboring arteries form what?
aterial anastomoses
What are the structures in red marrow that are large capillaries with wide-open intercellular junctions?
blood sinusoids
Where are three locations where sinusoids occur?
bone marrow spleen liver
What are the smallest blood vessels, and the site of exchange of molecules between blood and tissue fluid?
capillaries
What are the smallest blood vessels, with a diameter from 8-10 micrometers, in which red blood cells pass through single file?
capillaries
What is the name for a network of capillaries running through tissues?
capillary beds
There is little smooth muscle in the tunica media of veins--what is substance is there mostly instead?
collagen
What do arterial anastomoses form?
collateral channels
What are the two main types of capillaries?
continuous
What is the most common type of capillary?
continuous
Where are one-way valves in some veins found?
limbs
What substances can use direct diffusion into and out of capillaries?
lipid-soluble molecules
What is the diameter of arterioles controlled by?
local factors in the tissues sympathetic nervous system
About how many new blood cells are formed each day?
100 billion
Where are three locations where fenestrated capillaries can be found?
kidney intestines pancreas
Where is most yellow marrow located in adults?
long bones (appendicular skeleton)
Veins conduct blood from capillaries toward the heart, and blood pressure is much lower/higher than in arteries.
lower
What is the central blood-filled space of a vessel?
lumen
Where does the inner half of large vessels receive nutrients from?
luminal blood
What do lymphoid stem cells give rise to?
lymphocytes
What are the two progeny stem cell types of blood cells?
lymphoid myeloid
In the formation of leukocytes, lymphocytes form directly from what?
lymphoid stem cells
What are megakaryocytes formed from?
megakaryoblasts
What types of tissues have reduced blood flow through capillary beds?
metabolically inactive
What are the two parts of a capillary bed?
metarteriole thoroughfare channels
In the formation of leukocytes, monocytes form what?
monoblasts (myeloid line)
Which arteries have a thick tunica media relative to vessel size?
muscular
Which types of arteries lie distal to elastic arteries, with diameters ranging from 1 cm-0.3 mm, and includes most of the named arteries?
muscular (distributing) arteries
In the formation of leukocytes, granulocytes form from what?
myeloblasts
