Blood vessels and Lymphatics Flashcards
Describe the overview of circulation
Pump (heart) to arterial system to capillary bed (to lymphatic) to venous system and then back to the heart
What is the difference between Veins and Arteries in terms of tissue type?
Veins are mainly collagenous, fibrous tissues
Arteries are mainly muscular tissues
What are the three layers of all blood vessels and briefly state their tissue type?
- Tunica interna (intima): endothelium and connective tissue
- Tunica media: muscle and connective tissue
- Tunica externa (adventitia): thick layer of connective tissue
What is Tunica interna’s lining?
It is lined by specialized simple squamous epithelium called endothelium
Where does the endothelium lining stop?
It is continuous throughout the entire vascular system
What hormones does endothelium release?
Endothelins, and they constrict the smooth muscle within the walls of the vessel (to increase BP)
What is the role of basal lamina?
It is the basement membrane that effectively binds to the endothelium to the connective tissue
What is the thick layer found in larger arteries?
Internal elastic membrane
Where is the internal elastic membrane?
Located at the boundary with the tunica media in larger arteries beneath tunica interna
What is the purpose of the internal elastic membrane in large arteries?
It provides structure while allowing the vessel to stretch
What type of muscle cells are the lining of vessels contained of?
Smooth muscle cells
What is the thickest layer in arteries?
Tunica media
What is the thickest layer in veins?
Tunica externa
Define vasoconstriction and vasodilation and state their importance
Vasoconstriction is the contraction of the circular muscles (this decreases the diameter of the vessel lumen which increases the BP)
Vasodilation is the relaxation of the circular muscles (this increases the diameter of the vessel lumen which decreases the BP)
What is the tunica media composed of?
Concentric layers of helically-arranged smooth muscle cells
What type of fibres does the tunica externa contain?
Primarly composed of Collagen I fibres
What arteries are closest to the heart?
Elastic large arteries
Describe elastic arteries and name few
They are conducting arteries closest to the heart.
They expand during systole, and elastic recoil during diastole.
Aorta and pulmonary artery are elastic arteries.
What is the function of muscular arteries?
They control distribution of blood to regions and organs
They regulate blood flow (by constriction or relaxation of their walls)
How do muscular arteries regulate blood flow?
By constriction and relaxation of their walls
List the three features of muscular arteries?
They have a thick layer of circular smooth muscle in their tunica media
They can accommodate an increase in diameter
They can contract to prevent haemorrhage
What do smooth muscle cells remain present in the media throughout all arteries?
Because the elements of control over distribution and flow is crucial in arteries
What are arterioles?
They are arteries less than 0.5mm in diameter
What is the difference between metarterioles and capillaries?
Metarterioles and capillaries are same in diameter but the first has on layer of smooth muscle in their walls, whilst the second is a tube of endothelium only
What does the subclavian artery turn into?
Axillary and brachial, then radial and ulnar
What is the name of the artery near the armpit?
Axillary
What is the name of the artery near the clavicle?
Subclavian
What is the name of the artery near the arm?
Brachial
What are the extra vessels around the elbow, shoulder and wrist? and what is their function?
They have collateral anastomoses and they allow flow/supply beyond the joint when it is compromised by being squeezed or in a weird position