Lecture 6- Circulatory system anatomy, Arteries and Veins Flashcards
What’s the first step in the supply path from the heart to the foot?
- Left side of heart into ascending Aorta. Aorta then arches up (aortic arch) and descends towards diaphragm (descending aorta).
- All of this is known as the thoracic aorta as in thoracic cavity.
What happens in the supply path after the thoracic aorta?
Enters abdominal aorta
In the supply pathway what happens to the abdominal aorta at the belly button?
At belly button the abdominal aorta splits into two to form the left and right common lilac arteries that go to the left and right lower limb
In the supply pathway what happens after the branching to left and right common iliac arteries?
The Common iliac artery branches:
- External iliac artery go to lower limb (leaves abdominal cavity)
- Internal iliac artery supplies the bowl of the pelvis.
In the supply path what happens when the are changes from the pelvic/abdominal area to the leg?
Have a name change the external iliac artery now becomes the femoral artery
In the supply path what happens at the knee?
Behind knee (flexor aspect) is the popliteal artery
What does the popliteal artery branch into?
Forms three major arteries, one is the posterior tibial artery. This sits at back of leg and goes to sole of foot to form a connection with plantar arches
Put the arteries in order of the supply path from the heart to the foot:
posterior tibial artery
thoracic aorta
femoral artery
spilt into right and left common iliac arteries
left side of heart
connect with plantar arches at sole of foot
spilt into external iliac artery and internal iliac artery
abdominal aorta
popliteal artery
left side of heart
thoracic aorta
abdominal aorta
spilt into right and left common iliac arteries
spilt into external iliac artery and internal iliac artery
femoral artery
popliteal artery
posterior tibial artery
connect with plantar arches at sole of foot
Put the veins in order of the deep drainage path from the foot back to the heart:
Popliteal vein Inferior vena cava Right Atrium External illiac vein Posterior tibial vein Femoral vein Plantar venous arch Common illiac vein
Plantar venous arch Posterior tibial vein Popliteal vein Femoral vein External illiac vein Common illiac vein Inferior vena cava Right Atrium
What is the name of the vein that acts as superficial drainage? Where does it join with the deep drainage pathway?
Great Saphenous vein:
- Longest vein in the body
- Runs in the hypodermis (right below the skin)
- Goes deep and joins the femoral vein at the groin
How many layers does the walls of blood vessels have and what are these called?
3 layers:
- Tunica Intima
- Tunica Media
- Tunica Adventitia (Externa)
What is the tunica intima made of?
-Endothelium: A simple squamous epithelium which
lines the lumen of all vessels.
-Sub-endothelium: A sparse pad of loose FCT.
cushioning the endothelium (provides support)
-Internal Elastic Lamina (IEL): a condensed (thin) sheet of elastic tissue.
How does the internal elastic lamina compare between veins and arteries?
The IEL is well developed in arteries and less developed in veins
Where is the internal elastin lamina located?
Boundary between intima and tunica media
What is epithelium?
A class of cells epithelia cells (form boundaries), provide a non-stick function in blood preventing clotting
What can be seen in a picture showing the histological structure of the artery?
- Very thin intima should be able to see the internal elastic lamina at boundary and small dots going into the lumen are the protruding nuclei of endothelium cells
- The tunica media will then be the thickest layer (stained pink). Smooth muscle cells will be in between the collagen and elastin fibers but we won’t be able to see them in a histological slide
- Then the Tunica Adventitia
What is the tunica media made of?
-Smooth muscle
-A variable content of connective tissue fibers,
mainly elastin (rubber recoil) and collagen (tensile strength)
-Thickness of the media is proportional to both
vessel diameter and blood pressure.
What will have a bigger tunica media: and artery or vein?
An artery will always have a thicker tunica media than a vein as it carried pressurized blood.
What is the Tunica Adventitia made of?
- Loose FCT with a high content of collagen (tensile strength) and variable amount of elastin (recoil).
- In larger vessels, the adventitia contains the vasa vasorum.
- Lymphatics and autonomic nerves are also found in this region
What is the vasa vasorum?
- Literally means the ‘vessels of the vessel’
- Blood vessels with thick walls need their own blood supply (they themselves are own organ system)
What is the main function of the Tunica Adventitia?
It is the outer tensile sheath of the blood vessel stopping it from expanding any more (diameter limiting)
How are the smooth muscle cells in the Tunica Media
orientated? What does this mean?
Circumferentially, means that when they shorten the vessel constricts and when lengthens it dilates
Structurally what is the difference between a Thoracic Aorta and Femoral artery?
- Thoracic aorta is a elastic artery, meaning there are layers of elastin all throughout the tunica media. This means the tissue has a lot of recoil. Because there is so much elastin in the tunica media there is no need for any in the tunica adventitia
- Femoral arteries on the other hand are muscular arteries and so don’t have as much elastin
What are arterioles?
Smallest arteries (last of supply network) before turning into capillaries
What are Venioles?
Smallest veins (1st part of venous drainage system), come off capillary beds
What is pulse pressure what is the trend in how it changes?
- Initially there is pressure pulses (contraction, relaxation). However, in capillaries the supply muscle we want a steady flow for exchange. The pulse effect is therefore dampened by taking up energy of the pulse into the elastic component of artery walls
- Pulse pressure therefore decreases as goes down
What is the main function of arterioles?
The resistance vessels of the circulation - determine blood pressure.
What is the basic function of capillaries?
Site of exchange between blood and tissues.
What is a special feature of venioles? Why is it needed?
It is a low pressure drainage system and so valves ensure that the blood doesn’t go backwards/ in the wrong direction.
What are the functions of veins?
- Low pressure, large volume transport system
- One-way (unidirectional) flow back to the heart
- Capacitance vessels= have spare capacity and so can hold extra blood volume
What is the histological structure of veins like?
-Irregular, flattened shape with large lumen & thin
wall.
Three layers:
1. Intima- very thin
2. Media -Much thinner than arteries - a few layers of
smooth muscle (often in two distinct layers).
3. Adventitia -Often the thickest layer of a vein, lots of collagen prevents over distending/expanding.
How do live veins compare to dead veins? Do arteries do this?
Live vein plump and round, dead collapses and crinkles (arteries don’t do this)
What are Neves that run in the same tissue as arteries and veins called?
Neurovascular
What do valves do in veins of the leg?
A contraction squeezes the vein and the action of a valve ensures that blood can only go up to the heart (not follow gravity down to feet)
What causes varacus veins?
if vein dilates too much the valves no longer close/function properly resulting in baracus (visible veins). These are often elongated which results in the snake like appearance.
What are the branches that exist from the aortic arch?
- Brachiocephalic trunk (goes towards right)
- Left common carotid artery (goes up to brain)
- Left subclavian artery (goes to left under collarbone)
