1. Vascular Histology Flashcards
Overview of Blood Vessels’ Histology Classification according to: • Vessel wall structure and composition: • \_\_\_\_. • Individual \_\_\_\_. • Lumen diameter. • \_\_\_\_.
Aorta: highly muscular, rich in SM and elastin > operates at a very high ____ regime; just downstream of the heart, the high pressure is due to the pumping of heart
Vena cava: large lumen that houses large volume of blood > operates in a low ____ environment, and they serve as ____ for large volumes of blood (arteries do not have that function)
Capillaries: involved in shunting of blood from arteriole to vein, and exchange substances, fluids and gases
thickness
layer (tunica) thickness
working pressure
blood pressure
blood pressure
resorvoirs
General Structure of the BV
- Tunica Intima:
- ____
- +/- Connective Tissue
- +/- Internal Elastic Lamina
- Tunica Media:
- ____
- Collagen Fibers
- Elastic Laminae
- Tunica Adventitia:
- ____
- Vasa vasorum
Every BV shows this general structure:
Lumen: tunica intima, the cells lining that are in contact with fluid = endothelium (____); may find a CT or internal elastic lamina below (depending on the vessel)
Next: tunica media, presence of SM > secrete an ECM rich in elastic lamina (contractile) and in collagen (resistance)
Outside: tunica adventitia, mostly made of CT (some SM, but not as much as TM), and the presence of ____ (BV that vascularizes a BV)
endothelium
smooth muscle cells (SMCs)
connective tissue
simple squamous
vasa vasorum
Endothelial Biology Endothelium: simple squamous epithelium. • Biological functions: • Modulation of smooth muscle activity: • SM relaxing factors: e.g. \_\_\_\_. • SM contraction factors: e.g. \_\_\_\_.
• Prevention of blood clotting:
• Secretion of ____: inhibits platelet binding to
the endothelium.
- Initiation of blood clotting cascade:
- Secretion of ____: trigger of common pathway of blood coagulation.
- Regulation of traffic of inflammatory cells:
- ____ trans-endothelial migration.
NO
endothelin 1
prostacyclin
tissue factor
selectin-mediated
Arteries: Structure
Within the lumen > RBC and some WBC are interspersed > indication of ____
Underneath the endothelium and BL there may be a ____ of CT and an ____ (not present all the time)
Difference between artery and vein: ____; here it is a deeply stained layer due to high levels of SM cells (making a dense ECM composed of elastin and collagen) resulting in a very muscular layer (veins are the opposite)
Tunica adventitia > ____
If artery is thick enough, in adventitia you will see the ____; when the BV becomes so large > how do you provide the SMC with metabolites/glucose > in adventitia there is going to be innervation of BV (everything is exchanged at the level of the vaso vasorum [adventitia], not at the lumen)
BV
subendothelial layer
internal elastic lamina
tunica media
loose CT
vaso vasorum
Veins: Structure and Function
The lumen may be wide, but the individual layers are ____ (opposite of artery)
Subendothelial layer only in ____; no internal elastic lamina in most examples
In many veins > valves (projections of ____ into the lumen of the vein) > prevent the backflow of blood (important because it is a low pressure environment); ____ do not have valves
TM is much ____ than arteries, the orientation of SMC is not as ____
TA (also much thinner) > loose CT > ____ present in larger veins
thinner
larger veins
endothelium of TI
large veins
thinner
regular
vaso vasorum
Classification of the Blood Vessels
• Elastic Arteries (____ mm diameter):
• ____ vessels from the heart: Receive blood
under pressure.
• Aorta, pulmonary artery, carotid, subclavian.
- Muscular Arteries (Large ____ mm; small ____ mm):
- Selective ____ to different organs.
- Renal, hepatic, superior and inferior mesenteric.
• Small Arteries and Arterioles (____ μm):
• ____ vessels: regulate systemic blood pressure
and blood flow through capillaries.
- Capillaries (____ μm):
- ____ vessels.
• Venules (\_\_\_\_ μm): • Migration of \_\_\_\_ to tissues . • Small, Medium, and Large (\_\_\_\_ mm) Veins: • \_\_\_\_ or \_\_\_\_ vessels.
10-25 mm
conducting
2-10
0.1-2
distribution
10-100
resistance
5-10
exchange
50-100
WBCs
0.1-30
capacitance
reservoir
General Structure of the Elastic (Conducting) Arteries I
• Aorta, pulmonary artery, carotid, subclavian.
• Tunica Intima - Thin • Endothelium – \_\_\_\_. • Subendothelium – \_\_\_\_. • Internal Elastic Lamina (IEL) – a.k.a. elastica interna, densely-packed \_\_\_\_.
- Tunica Media - Thick:
- ____ with elastic laminae (or lamellae).
- External Elastic Lamina (EEL) – a.k.a. elastica externa, densely-packed ____.
• Tunica Adventitia - Thin
• Connective Tissue.
• ____ – vascular plexuses within the
vessel wall.
Undergo cycles of ____ due to the fact that the heart is pumping blood a v high pressures
Reason why they’re rich in SM and EF > to cope with the changes in BP; if they were not ____ > the vessel would rupture
By absorbing energy from cycles of pumping > they ____ out the pressure; closer to heart you see ____ cycles, and the farther you travel the cycles ____ due to the absorption of energy by the elastic fibers (act as shock absorbers)
Majority of thickness: ____
endothelial cells
CT
elastic laminae
concentric SMCs
elastic laminae
vasa vasorum
pumping
elastic
smooth
larger
shrink
tunica media
General Structure of the Elastic (Conducting) Arteries II
Endothelial cells > subendothelial layer > internal elastic lamina > TM: SMC, largest component, organized in a ____ manner, between layers of SMC > ____ (organized in circumferential manner) > mostly involved with ____ of the vessel > external elastic lamina (similar to IEL, but more densely packed) > TA: loose CT > presence of ____, in additions to ____
circumferential elastic lamina expansion fibroblasts BV
General Structure of the Elastic (Conducting) Arteries II
- Tunica Intima - Thin
- Endothelium – epithelial cells.
- Subendothelium – CT.
- Internal Elastic Lamina (IEL) – elastin.
Can distinguish the ____ between the ____ (SECT, presence of fibroblasts)
Separating intima from media: IEL, doesn’t look very different from the ____ (fiber, but lamellae bc they look like sheaths that CF-organized) found in the TM
endothelial cells
connective tissue
elastic lamina
General Structure of the Elastic (Conducting) Arteries III
- Tunica Intima - Thin
- Tunica Media - Thick:
- Concentric ____.
- Concentric ____.
- Interspersed collagen fibers.
- ↑ ____ (and ↓ ____) in vessels with smaller diameter.
- ____ External elastic lamina (EEL) – distinct boundary between ____ and ____ in smaller vessels.
- Tunica Adventitia - Thin
SMCs elastic laminae SM elastic laminae \+/- tunica media tunica externa
General Structure of the Elastic (Conducting) Arteries IV
• Tunica Adventitia – Thin:
• CT that gradually merge with ____.
• ____ (“vessels of the vessel”) – small arteries and veins that that form
____.
• ____ (“nerves of the
vasculature”) – autonomic nerve endings.
• ____ vessels.
____ may be surrounding the BV, nerves and lymphatics
surrounding tissues' CT vaso vasorum capillary plexuses nervic vascularis lymphatic adipose
General Structure of the Muscular (Distributing) Arteries I
• Examples: brachial, femoral, radial.
• Selective distribution and blood flow
regulation to different organs.
• Tunica Intima: • Endothelium. • +/- Subendothelium. • Internal Elastic Lamina – often showing folding (“\_\_\_\_”) due to contraction of the TM. • Tunica Media: • Lower abundance of \_\_\_\_. • Higher abundance of \_\_\_\_. • External Elastic Lamina – present in larger vessels. • Tunica Adventitia: • Equal thickness to \_\_\_\_ (or thicker). • Vasa vasorum, nervi vascularis.
May or may not be presence of a ____
IEL > folding due to it being quite dense, and there is no pressure acting on elastin and it has such a powerful recoil that it recoils the entire vessel and it becomes smooth/scalloped (doesn’t happen in aorta bc TM is so ____ it prevents scalloping)
Higher abundance of SMC compared to elastic lamina within the TM
TA > may be as thick as the TM, or it may be thicker > still contains ____
scalloped elastic laminae SM bundles TM subendothelium dense innervation
General Structure of the Muscular (Distributing) Arteries II
Smaller muscular arteries:
Tunica intima almost exclusively
____.
Lower number of layers of ____ in the TM.
Internal and external elastic laminae less ____.
Presence of ____ in a longitudinal manner
endothelium
SMCs
prominent
vaso vasorum
Small Arteries and Arterioles I
• Resistance vessels:
• Regulation of ____: SMC
contraction → ____ → ____
blood flow.
- Tunica Intima:
- Endothelium
- No ____.
- May show ____.
- Tunica Media:
- ____ of SMCs circumferentially disposed.
- No ____.
- Tunica Adventitia – ____.
- Collagen and isolated elastic fibers.
Presence of ____; striated muscle
peripheral blood pressure
peripheral resistance
lower
subendothelium
IEL
1-2 layers of SMCs
EEL
thin
adipocytes
Small Arteries and Arterioles II
- Tunica Intima:
- Endothelium
- No ____.
- May show IEL.
- Tunica Media:
- ____ of SMCs circumferentially disposed
- No____.
- Tunica Adventitia – thin.
- Collagen and isolated elastic fibers.
Can use size of ____ to gauge how big the vessel is
subendothelium
1-2 layers
EEL
RBC