lecture 6 - arteries & veins Flashcards
Where do all major arteries originate?
The aortic arch
What branch of the aorta do the arteries of the legs ultimately originate from?
The descending aorta
What are the 6 major arteries of the leg, in descending order (superior to inferior)?
Common iliac, external iliac, femoral, popliteal, posterior tibial, plantar arch
What is the location of the popliteal artery?
Runs behind (posterior) to the knee
What arterial feature supplies the feet?
Plantar arch
What major vein that directly drains into the heart do the veins of the legs ultimately lead to?
Inferior vena cava
What is the order of the 7 major veins of the legs, in ascending order (inferior to superior)?
Plantar venous arch, posterior tibial, popliteal, great saphenous, femoral, external iliac, common iliac
What is the key superifical vein of the legs?
Great saphenous
What venous feature drains the feet?
Plantar venous arch
What are the 3 layers of the wall of a blood vessel?
Tunica intima, Tunica media, Tunica adventitia(externa)
What is the innermost later of a blood vessel?
Tunica intima
What is the outermost layer of a blood vessel?
Tunica adventitia (or externa)
How many layers make up the tunica intima?
3
What are the 3 layers of the tunica intima?
Endothelium, sub-endothelium, internal elastic lamina
What is the innermost layer of the tunica intima (in direct contact with the blood inside the vessel)
Endothelium
What are the characteristics of the endothelium of the tunica intima?
Simple squamous epithelium
What is the sub-endothelium of the tunica intima?
A sparse pad of loose fibrous connective tissue (FCT) that cushions the endothelium
What is the key function of the sub-endothelium of the tunica intima?
Cushions the underlying endothelium
What is the internal elastic lamina?
A condensed sheet of elastic tissues found at the outermost layer of the tunica intima in blood vessels
How does the internal elastic lamina of blood vessels differ between arteries and veins?
It is well developed in arteries but less developed in veins
What is the key component of the tunica media?
Smooth muscle
What are the key characteristics of the smooth muscle of the tunica media?
Involuntary, striated
What are the components of the tunica media?
Smooth muscle and connective tissue fibres
What connective tissue fibres are found in the tunica media, and what are their functions?
Elastin and collagen, for elasticity and strength respectively
What is the thickness of the tunica media proportional to?
Vessel diameter and blood pressure - higher pressure = smaller diameter = thicker tunica media
What are the relative thickness of the tunica media in arteries and veins?
Veins have lower pressure than artieries, so have thinner layers tunica media
What is the structure of the tunica adventitia?
A sheath of loose FCT with a high content of collagen and varying amounts of elastin
What component of the tunica adventitia provides the blood supply of the smooth muscle of the tunica media?
The vasa vasorum
What are the vasa vasorum?
Small vessels in the tunica adventitia that supply the smooth muscle of veins and arteries
The lympathatic and nervous system components of the blood vessels are found in which layer?
The outermost layer - the tunica adventitia
What type of nerves are found in the tunica adventitia?
Autonomic - both sympathetic and parasympathetic
Does the difference between systolic and diastolic blood pressure in blood vessels increase or decrease with distance from the heart?
Decreases
Why does the difference in diastolic and systolic blood pressure in vessels decrease as you get further from the heart?
Initially, in the aorta the blood is ejected with high force into elastic arteries, causing them to store energy which is released as the heart relaxes, repressurising blood near the heart and decreasing the difference between systolic and diastolic. This phenomenon means as you move away from the heart, flow is steady
Are arteries closest to the heart more elastic or more muscular compared to their more peripheral counterparts?
More elastic
Where are arterioles located in the arterial supply network?
At the end, as the smallest type of artery.
How do arterioles influence blood pressure and heart activity?
The resistance of these vessels determine the pressure in the supply networks and the muscle tone of the arterioles determines how hard the heart has to push to pump blood to the extremities.
What is the basic function of a capillary?
To exchange blood with tissues
What are venules?
The starting of the cardiovascular collecting/drainage system.
What is the other name for venules?
Post-capillary venules
What structure is found within venules and ensures unidirectional blood flow?
monocuspid valves
What is the name for flow of blood in one direction within a vessel?
Unidirectional flow
Do veins have thick or thin walls?
Thin
Why do veins have spare capacity for more blood volume?
So that blood can ‘pool’ in the vessel
What is the name for veins that have spare capacity, and can take up extra blood volume?
Capacitance vessels
How many layers do the walls of veins have?
3
How many layers of smooth muscle does the tunica media of veins have?
A few layers, usually with 2 distinct
What is the thickest layer of a vein vessel wall?
The tunica adventitia
What characteristic of the tunica adventitia of veins limits the stretching of the vessel during venous pooling?
High collagen levels to provide strength
For an artery and vein with the same flow/volume through them, what is their relative cross sectional area?
Veins have approximately double the cross sectional area
What is the cause of varicose veins?
Leaky valves in veins can cause the veins to balloon outwards due to back flow.
What outside component helps to push blood through a vein to return it to the heart?
Skeletal muscle contraction
