Anatomy of the Cardiovascular System 2 Flashcards
What are the layers of a blood vessel?
Tunica intima
Tunica media
Tunica adventitia
What is the basic structure of the tunica intima?
Simple squamous epithelium
Basement membrane
Connective tissue
What is the basic structure of the tunica media?
Smooth muscle tissue
Elastic tissue
What is the basic structure of the tunica adventitia?
Fibrous connective tissue
What in the most outer layer of a blood vessel?
Tunica adventitia
What is the difference between an artery and its accompanying vein?
Arteries are generally smaller in diameter and will have a thicker wall than their accompanying vein
Arteries have a thick media and thin adventitia
Veins have a thin media and a thick adventitia
What are the different types of arteries?
Elastic
Muscular
Arterioles
What is the only elastic artery?
The aorta
What is the function of the aorta?
Pressure reservoir
What happens to the aorta during diastole?
Heart relaxes, pressure falls and the artery recoils so that pressure is maintained on the blood
What is the recoil and stretchability of the aorta due to?
Presence of extensive amounts of elastic fibres in the tunica media in the form of laminae, these fibres are secreted by smooth muscle
What is the function of the muscular arteries?
Controls distribution of blood to regions
In muscular arteries, elastic fibres are concentrated in two well-defined sheets, what are these?
Internal elastic lamina (just under the epithelium)
External/outer elastic lamina (between tunica media and adventitia)
Smaller muscular arteries gradually change histologically to become what?
Arterioles
What is the difference between the layers of muscular arteries and arterioles?
Arterioles do not have a tunica adventitia
What is the function of the arterioles?
Controls blood flow to the capillary beds and controls blood pressure
What is the function of capillaries?
Main exchange site for nutrients and gases
What are pericytes and what is their function?
Pericytes are an incomplete layer of cells surrounding the basement membrane which have contractile properties and help to control flow of blood in the capillarie
Is the blood pressure in capillaries high or low?
Low
What extra property do continuous capillaries have?
Can control what is exchanged
How is material passed through continuous capillaries?
Must pass through the cell or between the cells via selective transport mechanisms
What extra property do fenestrated capillaries have?
Have fenestrations (pores) of up to 100µm
What is the function of diaphragms in fenestrated capillaries?
Filter molecules by molecular weight and/or charge
What is the difference between continuous and discontinuous capillaries?
What does the structure of discontinuous capillaries allow?
Discontinuous capillaries have gaps between the endothelial cells and basement membrane
Allows free passage of fluid and cells
What has a larger diameter; sinusoids or discontinuous capillaries?
Sinusoids
Where are sinusoids found?
Where large amounts of exchanges take place e.g. liver
What does the tunica intima of sinusoids contain?
Phagocytic cells
What is the function of valves in veins?
Prevent the back flow of blood
What are the main differences between superficial and deep veins?
Superficial veins are thick walled and have no surrounding support
Deep veins are thin walled and have surrounding support from deep fascia and muscles
What does the lymphatic system drain into?
Systemic venous system
Where are lymph nodes found?
Alongside major veins and around origins of major arteries
How are lymph nodes clinically important?
In tumour cell metastases
What are the features of lymph capillaries?
Blind-ended capillaries lined by very thin endothelium
No fenestrations
Absent/rudimentary basal lamina
Anchoring filaments linking endothelial cells to surrounding tissue
No RBCs in lumen
What is the nerve supply of blood vessels?
Sympathetic, or sympathetic and parasympathetic
