7. Vascular Disorders & Thrombosis: Anatomy/Microanatomy

What is this showing?

severely atrophied thymus, which is largely devoid of lymphocytes

What is the main function of the circulatory system?

deliver nutrients and remove waste products from cells

True or false: The circulatory system is composed of blood, a central pump, and driving force to distribute blood through the system, most often known as the heart, and a vascular network which exchanges the nutrients and waste.

true

Arteries are under ________ pressure and move blood ________ from the heart.

high; away

Veins are under ________ and move blood ________ the heart.

low; towards

second network of vessels which drain the extracellular space that most, but not all, multicellular organisms have

lymphatics

Lymphatics ________ the veins and empty back into the blood via the ________ ________. That empties into the ________ ________.

parallel; thoracic duct; vena cava

largest vein of all that goes to the right side of the heart

vena cava

The walls of both arteries and arterioles will appear ________, both grossly and histologically. They can be identified based on the ________ and number of ________ fibers distributed throughout the wall.

thicker; thickness; elastin

often the closest to the heart, as they must withstand large pressures from the pump and be able to stretch (elastin fibers) and recoil to keep a continuous flow of blood

arteries

Arteries have a ________ lumen and ________ resistance. This facilitates ________ blood flow.

large; minimal

Arteries have a ________ vessel wall. It is made up of ________ muscle and ________ fibers.

thick; smooth; elastic

What is the purpose of the smooth muscle and elastic fibers?

tensile strength and elasticity

What is the main function of the arterioles?

provide resistance to the circulatory system as the blood moves further and further away from the heart and pressure will drop

What type of lumen do arterioles have?

narrow

What do arterioles respond to? What does this cause? What does this help maintain?

sympathetic and parasympathetic innervation; constriction and relaxation of vessels; blood pressure

All vessels have what layers?

1. tunica intima

2. tunica media

3. tunica adventitia

single layer around the lumen

tunica intima

deep to tunica media that allows the vessel to be dynamic

tunica media

supplies blood to arteries

tunica adventitia

What is the function of capillaries?

site of nutrient and waste exchange between the blood and surrounding tissue (extracellular/extravascular compartment)

What are the 3 types of capillaries?

• continuous

• fenestrated

• discontinuous

What are the types of capillaries named for?

type of endothelial lining and basement membrane

What will differences in the lining allow for?

different substances to pass through and are present in different tissues

most numerous vessel of the circulatory system, but only contain 5% of the total blood volume at one time

capillaries

What is the velocity of blood flow through capillaries? How are the lamina? What does this do? What does this allow for?

slow; small; RBCs move through capillaries in a single file fashion; allows for time for exchange of nutrients and waste

The wall of the capillary is very ________, which also helps to facilitate the movement.

facilitate

In most cases, there is no more than what amount of space between a capillary and a cell?

1 mm of space

What is this?

capillary

What are the characteristics of continuous capillaries?

1. continuous endothelium

2. continuous basement membrane

Which type of capillary is the least leaky?

continuous

What is the only type of capillary that the brain has?

continuous

Continuous capillaries allow for the passage of only ________ molecules, as well as the exchange of ________ and ________, which can exchange through ________ of the endothelial cell. These capillaries are present in tissues which do not require or necessarily want the exchange of ________ products.

small; O2; CO2; microvesicles; larger

In what tissues can continuous capillaries be found?

B
M
L
B

• brain (blood brain barrier)

• muscle

• lung

• bone

What are the characteristics of fenestrated capillaries?

1. specialized spaces between endothelial cells (discontinuous endothelium)

2. continuous basement membrane

What is significant about the continuous basement membrane in fenestrated capillaries?

helps in keeping certain products within the lumen of the capillaries because it is negatively charged and will repel negatively charged items like albumin

What is significant about the discontinuous endothelium in fenestrated capillaries?

allows for the exchange of slightly large products and is selective about what passes through

In what tissues are fenestrated capillaries present int?

R
I
E
C
C

• renal glomeruli

• intestinal villi

• endocrine glands

• chroid plexuses

• ciliary processes of the eye

Which type of capillary are the most leaky?

discontinuous

What are the characteristics of discontinuous capillaries?

1. endothelial cells don’t overlap

2. discontinuous basement membrane

Discontinuous capillaries allow for ________ passage of molecules from the ________ lumen into the ________ space.

maximum; vascular; extracellular

In what tissues are discontinuous capillaries found?

L
S
B
L

• liver sinusoids

• spleen sinusoids

• bone marrow

• lymph nodes

What are veins and venuoles mostly composed of? What does this allow for?

collagen; distention more than contraction

Veins and venuoles have little ________ ________ and ________, unlike arteries.

smooth muscle; elastin

Veins and venuoles can hold up to what percent of total blood volume?

65%

The vascular wall is ________ both grossly and histologically.

thinner

What does blood passage in veins and venuoles depend on?

O
C
I

• one way valves to present back flow

• contraction of skeletal muscles

• increased pressure gradient due to increased pressure in the heart (cardiac suction effect)

What contributes to the most venous flow and helps with the movement of blood?

contraction of skeletal muscles

Why are one way values important for vein and venuoles?

because the pressure within the vein is relatively low

The return trip to the heart begins with the ________ ________ ________. It has a composition similar to ________, but will develop thin layers of ________ ________ the further away from the ________ they are.

post capillary venule; capillaries; smooth muscle; capillary

gives elasticity to vessels

elastin

What stain is used to highlight the elastin in vessels?

verhoff’s elastin stain

What is the microanatomy of elastin?

• tunica intima (endothelium, elastin)

• tunica media (smooth muscle)

• tunica adventitia (connective tissue)

Lymphatics surround ________ and always run in concert with ________. They begin as ________ ________ lymphatic capillaries. They have ________ endothelial cells and large ________ ________, which can accommodate ________ particles into their lumen.

microcirculation; vasculature; blind ended; overlapping; interendothelial gaps; larger

What moves lymph forward towards the heart?

valves and contraction of skeletal muscles

Lymphatic vessels are ________ and a ________ pressure system like ________. Therefore, they have ________ and require ________ of ________ for movement of lymph.

distensible; low; veins; valves; contraction; muscle

Lymphatic vessels drain into ________ lymphatic vessels, pass through ________ ________, and eventually lead to the ________ ________, which drains into the ________ ________, returning lymph into circulation.

larger; lymph nodes; thoracic duct; vena cava

True or false: The pressure within the lumen of the lymphatic vessel acts as a bit of a valve closing these gaps and preventing escape of the flow of lymph from the lumen, meaning it can get it but it can’t get out.

true

What lines all the components of the circulatory system?

endothelium

What are the functions of the endothelium?

F
I
I
A
H

• fluid distribution

• inflammation

• immunity

• angiogenesis

• hemostasis

Normal endothelium is ________, which helps to regulate ________ and prevent ________ formation, and ________, which helps break down the complexing of ________ into ________.

antithrombic; hemostasis; clot; profibrinolytic; fibrinogen; fibrin

specialized vascular networks formed by arterial blood vessels through the center of large venous sinuses

rete mirabile

What is the overall function of the rete mirabile? How does it do that?

R
I
O
E

countercurrent exchangers

• regulating temperature

• ionic contraction gradients

• O2/CO2 exchange

• equalized blood pressure in arteries before reaching the brain

A rete mirabile is predominant in ________, is located at the ________ of the ________, and is ________.

ruminants; base; brain; bilateral

True or false: As arterial blood travels through the rete mirabile, the venous blood surrounding allows for it to cool through countercurrent exchange. Located around the right and left internal carotid arteries as they pass by the pituitary gland, as well as along the cranial floor.

true

space between parenchymal and stromal cells and microcirculation

interstitium (extravascular compartment)

What are the functions of the interstitium?

P
M
G
S

• provide pathways used by the microvasculature (vascular adventitia), lymphatic vessels, nerves, and trafficking leukocytes

• module systematic physiologic properties exerted by parenchymal cells

• general fluid pool/reservoir providing cushioning effects for organs, water/ion reserves

• structural framework for cell survival

structural, adhesive, and absorptive components within the interstitium

extracellular matrix

What is the extracellular matrix predominantly composed of and provides most of the structural support?

type I collagen

What else is the extracellular matrix composed of?

T
G
G
P

• type I collagen

• glycoproteins

• glycosaminoglycans

• proteoglycans

provide sites of attachment for the structural proteins, as well as a site of adhesion for transmigrating leukocytes

glycoproteins

absorptive dissacharide complexes

glycosaminoglycans

hydrophilic and can bind large amounts of water and other soluble molecules

proteoglycans

What are the components of the extracellular matrix produced by?

P
F
G
M
T

• parenchymal cells

• fibroblasts

• glial cells (CNS only)

• macrophages

• trafficking leukocytes