AN 5.4 Explain functional difference between elastic, muscular arteries and arterioles

AN 5.4 Explain functional difference between elastic, muscular arteries and arterioles

S. No	Feature	Elastic Artery	Muscular Artery	Arterioles	Capillaries
	Type of vessel	Conducting	Distributing	Resistance	Exchange
	Size	> 10 mm	1-10 mm   Young-thin Old-thick(lipids deposition)	< 1 mm diameter	8 – 10 μm diameter
	Pressure	120 mm of Hg	120 mm of Hg	60  mm of Hg	12-30  mm of Hg
	Rate of blood flow	0.5m/sec	Rate keeps decreasing	0.5mm/sec	<0.5mm/sec
	Tunica intima	Endothelium + Sub endothelial connective tissue THICK	Endothelium + Sub endothelial connective tissue Present	Endothelium + Sub endothelial connective tissue Present	Single layer of endothelium resting on basal lamina of glycoproteins
	Internal elastic lamina	Ill defined	Prominent	Thin but distinct	Absent
	Tunica media	Elastic tissue> muscular tissue	Smooth muscle fibres> Elastic fibres (scattered)	Only plain muscle fibre	Absent
	External elastic lamina	Thin	Prominent	Little or no	Absent
	Tunica adventitia	Fibroelastic layer Prominent vasa vasorum	Fibroelastic layer Not prominent vasa vasorum	Loose connective tissue only	Absent
	Examples	Aorta, Pulmonary trunk & arteries, Brachiocephalic, Common carotid, Subclavian, Common iliac	Occipital, Radial, Ulnar, Popliteal	Afferent & Efferent arterioles in glomerulus	·      Continuous capillaries: skin, connective tissue, skeletal muscles, smooth muscles, brain & lung ·      Fenestrated capillaries: intestinal mucous membrane, pancreas, endocrine glands and renal glomeruli ·      No capillaries: cornea, articular hyaline cartilage, epidermis of skin, hair & nails, epithelial cells resting on basement membrane
	Function	Maintains diastolic blood pressure(  high systolic pressure à vessel distends due to elastic fibres à drives blood to periphery due to elastic recoil à vessel return s to normal caliberà maintains diastolic pressure)	Move blood by muscular contraction (ANS)	·      Regulate blood flow into capillaries ·      Regulate systolic pressure (by offering peripheral resistance)	Provide an area for exchange of gases, metabolites and nutritive material between blood and interstitial fluid
	Blood supply	·      Diffusion: Tunica intima and inner part of tunica media ·      Vasa vasorum: Outer part of tunica media and tunica adventitia	·      Diffusion: Tunica intima and inner part of tunica media ·      Vasa vasorum: Outer part of tunica media and tunica adventitia	Diffusion	None
	Nerve supply	Nervi Vasorum ANS (sympathetic and parasympathetic)	Nervi vasorum ANS( sympathetic and parasympathetic)	ANS (Only sympathetic)	ANS (peripheral n)