Exam 2: Circulatory System Pt2 Flashcards
As we age into our 20’s, what happens to elastic arteries?
width increases and number of elastic laminae increase in the tunica media
In muscular arteries, what increases after middle age? What does this cause? What vessels are greatly affected?
increase in collagen and proteoglycans–> decreases flexibility
coronary vessels
What can occur around age 50 and is an increase in systolic BP? What is it due to?
Hypertension
Due to:
- a DECREASE in elastic fibers and an
- INCREASE in collagen I
What is the term for “hardening of the arteries”?
Arteriosclerosis = Atherosclerosis
Where does arteriosclerosis primarily take place? What happens to the tunica intima and tunica media?
in largest arteries
Tunica intima–> becomes infiltrated with soft lipids causing lumen diameter to decrease
Tunica Media–> collagen I and sulfated GAGs can accumulate
What is an important factor and problem that can occur in elastic arteries associated with atherosclerosis?
blood is moving very fast and cells in tunica intima have trouble surviving–>
tunica intima is prone to injury, irritation, and infection–>
degeneration changes may occur in tunica intima –> increase in width of tunica intima, therefore a decrease in lumen size
What are short terminal arteriole branches that LACK a tunica media?
metarterioles
What do Metarterioles lead to?
capillaries and a thoroughfare channel–> which lead to venules
What do thoroughfare channels lack?
a tunica media
What controls blood flow into true capillaries?
pre-capillary sphincters (in metarterioles)
T/F. Metarterioles are found with all capillary beds.
true
What do metarterioles allow blood to do through capillaries?
pulse through capillaries
What are AVA’s? What do they have many of?
arteriovenous anastomosis = AV shunt
many ANS nerves (sym and parasym)
What vessel wall layer(s) in AVA’s are thicker?
tunica media and tunica adventitia
What is the function of AVA’s?
to control AVA lumen size and therefore the amount of blood into the capillaries
T/F. AVA’s are found in all capillary beds.
FALSE
recall, metarterioles ARE in all capillary beds though
Are AVA’s in the skin and stomach typically closed or open? What happens if the AVA does the opposite?
typically “closed” –> blood into capillary bed as normal
if AVA opens–> most of blood will BY-PASS the capillary bed
Are AVA’s in erectile tissues typically open or closed? What happens if the AVA does the opposite?
typically “open”–> less blood into erectile tissue capillaries
if AVA closes–> send blood into erectile tissue capillaries
What four things control/influence the blood flow into capillaries?
- metarterioles
- AVA’s (some locations)
- lumen size of terminal arteriole
- pre-capillary sphincters
What are the three general parts of the structure of a capillary?
- cells–> single layers of flattened endothelial cells
- Pinocytotic vesicles
- Cell junctions
What is the cellular make up of capillaries?
a single layer of flattened endothelial cells
What are found in capillaries that form tiny pockets through cytoplasm and function to move large molecules?
Pinocytotic vesciles
Describe the gap junctions of capillaries and what are there 2 functions?
Fasciae occludens b/w endothelial cells (tight junctions)
Function:
1. move macromolecules
2. allows more cell movement
What are the 3 types of capillaries?
- Continuous capillaries
- Fenestrated capillaries
- Sinusoidal capillaries
What is the MC capillary type?
continuous capillaries
Where care continuous capillaries located?
muscle, CT, many organs
What are often considered to be residual mesenchyme cells and are numerous on capillaries and venules and can secrete basement membrane and ECM components along with the ability to divide?
Pericytes
Can pericytes divide? Can they change into different cells? If so, what types?
yes and yes Types: - smooth muscle cells - endothelial cells - fibroblasts
What are the two functions of Pericytes?
- healing
2. regulate blood flow (maybe?–potential to)
Where are Modified continuous capillaries found? What makes them different?
in CNS
- zonula occludens instead of fasciae occludens
- barrier regulation by endothelium, but influenced by astrocytes
T/F. Astrocytes cover ~85% of capillary surface in CNS and produce products to influence the endothelium.
True
Where are Fenestrated capillaries located?
- pancreas
- intestines
- endocrine organs
- kidneys
(in organs where want to see enhanced exchange)
What is the structure of fenestrated capillaries?
pores with thin protein diaphragm containing 8 fibrils
What is the function of a fenestrated capillary?
to allow greater movement of molecules and cells
What are two other names for Sinusoidal capillaries?
sinusoids or Discontinuous capillaries
Where are sinusoidal capillaries found?
- bone marrow
- liver
- spleen
- lymphatic organs
- certain endocrine organs
(areas where want enhanced exchange b/w blood and body)
What is the structure of a Sinusoidal capillary?
- enlarged diameter
- many large fenestrae with NO protein diaphragm
What is the function of sinusoidal capillaries?
to enhance exchange b/w blood and tissues
How are veins similar to arteries? How are they different?
Similar: - have three tunics Different: - not as uniform in structure - often larger diameter - higher number
Describe the structure of a valve in a vein?
two flaps of tunica intima and fibroelastic CT
endothelium - CT - endothelium
What are the two functions of valves in veins?
- protection by preventing backflow
2. works with skeletal muscle to keep blood moving
What are the four types of veins?
- venules
- small veins
- medium veins
- large veins
What are the three types of venules and what variation in structure are they determined by?
- postcapillary venules
- colllecting venules
- muscular venules
determined by tunics, NOT by diameter
Describe the tunics of a Postcapillary venule:
- Tunica Intima
- Tunica Media
- Tunica Adventitia
- endothelium, small amount of CT and numerous pericytes
- none
- none
Describe the tunics of a Collecting venule:
- Tunica Intima
- Tunica Media
- Tunica Adventitia
- endothelium and small amount of CT
- none
- CT, fibroblasts, and some pericytes
Descrieb the tunics of a Muscular venule:
- Tunica Intima
- Tunica Media
- Tunica Adventitia
- present
- incomplete; some smooth muscle
- present with a few pericytes
What type of venule has numerous pericytes in its tunica intima?
postcapillary venules
What type of venule has no tunica media or tunica adventitia?
postcapillary venules
What type of venule has CT, fibroblasts, and some pericytes in its tunica adventitia?
Collecting venule
What type of venule has no tunica media, but has a tunica intima and adventitia?
collecting venules
What type of venule has an incomplete smooth muscle layer for its tunica media?
Muscular venules
What type of venule has a tunica adventitia with few pericytes?
muscular venules
collecting venules too, they just also have CT and fibroblasts
What will an incomplete tunica media in venules allow for?
products of inflammation to get through and loosen endothelial cell junctions and end up with “leaky” venules
What is usually the most dominant and thickest lumenal wall layer in veins?
tunica advantitia
What vein type has a structure similar to muscular venules, except there is a complete tunica media?
Small veins
What vein type are valves common in?
Medium Veins
What is the structure of the layers in Medium Veins?
- tunica intima
- tunica media
- tunica adventitia
- endothelium, basal lamina, CT w/ reticular fibers, ~ elastic fiber network (but no IEL)
- smooth ms, collagen, fibroblasts
- thickest; CT w/ collagen and elastic fibers and few smooth ms cells; vasa vasorum possible
What is the structure of the layers of Large Veins?
- tunica intima
- tunica media
- tunica adventitia
- similar to medium veins; thicker CT w/ fibroblasts and elastic fiber network
- complete, but thin
- thicker; fibro-elastic CT and vasa vasorum
What are the four exceptions to the typical structure of large veins?
- superficial veins of legs
- pulmonary veins
- superior vena cava
- inferior vena cava
What type of vein has a complete tunica media, but it is very thin?
large veins
How is the structure in Superficial veins of the legs different than the typical structure of large veins?
Tunica media–> well-developed
How is the structure of pulmonary veins different from the typical structure of large veins?
Tunica media–> well-developed
Tunica adventitia–> some cardiac muscle close to heart
How is the structure of the Superior Vena Cava different than the typical structure of large veins?
Tunica adventitia–> some cardiac muscle close to heart
How is the structure of the Inferior Vena Cava different than the structure of typically veins?
Tunica adventitia–> some cardiac muscle close to heart is possible AND some longitudinal smooth muscle
What are enlarged and winding superficial veins in the legs?
Varicose veins
What are three possible causes for Varicose veins?
- loss of skeletal muscle tone around the veins
- Degeneration of vessel wall
- Valve incompetence
What are varicose veins in the lower esophagus called? What individuals are they common in?
Esophageal varices
common in alcoholics–> caused by portal hypertension
What are varicose veins at the end of the anal canal called?
Hemorrhoids
What are the three functions of lymphatic vessels?
- drain excess intersitial fluid
- transport lymph to lymph nodes (foreign Ag detection in lymph nodes)
- Transport lymph to blood stream
What other vessels do lymphatic capillaries structurally resemble?
continuous blood capillaries
What are the four types/kinds if lymphatic vessels?
- Lymphatic capillaries
- Small lymphatic vessels
- Medium and large lymphatic vessels
- Lymphatic Ducts
What are the 5 things that make lymphatic capillaries different from continuous blood capillaries?
- blind ended (suddenly begin)
- NO pericytes*
- endothelial cells can overlap, but create clefts b/w cells allowing for easy movement of materials in/out
- NO fenestrae and NO tight junctions b/w endothelial cells*
- contain bundles of lymphatic anchoring filaments
What are the two things that Lymphatic capillaries LACK, that continuous blood capillaries have?
Lack:
- pericytes
- fenestrae and tight junctions b/w endothelial cells
What is one thing that Lymphatic capillaries contain that continuous blood capillaries don’t? What is the function of this structure?
contain bundles of lymphatic Anchoring Filaments (contain elastic fibers)
Fxn: support endothelial walls so capillaries stay open and hold to CT
What other vessel do Small Lymphatic Vessels resemble?
venules
In general, what other vessels do Medium and Large Lymphatic Vessels resemble?
larger vessel veins
skeletal muscle contraction propels lymph –similar to blood in veins
Describe overall how Medium and Large Lymphatic Vessels are structurally made up.
larger lumen and thinner walls
tunics blend together more than veins
Do small lymphatic vessels have all three layers of tunic?
yes; b/c they resemble venules
Do Medium and Large lymphatic vessels have all three layers of tunic? What about valves?
Yes-all 3 layers
yes- and are closely spaced
What is the structure of the three vessel layers making up Medium and Large lymphatic vessles?
- Tunica intima
- Tunica media
- Tunica adventitia
- endothelium and thin layer of CT with elastic fibers
- thin smooth muscle layers
- CT with collagen and elastic fibers
Where do the lymphatic ducts empty into the venous system?
at the junction of the right internal jugular and subclavian veins
What are the the two lymphatic ducts in the body?
Right lymphatic duct and the thoracic duct
Do lymphatic ducts have the three tunic layers?
yes
What is the structure of the three vessel wall layers of Lymphatic ducts?
- tunica intima
- tunica media
- tunica adventitia
- endothelium; several layers of collagen and elastic fibers; layer of condensed elastic fibers (similar to an internal elastic lamina)
- longitudinal and circular layers of smooth ms
- longitudinal smooth muscle cells; collagenous CT; vasa vasorum-like vessels present
