9 November 2011 Properties of Blood Vessels Capillary Exchange Baroreceptors Test 2 Recap and Grading Strategy Four versions, all new this year Degree of Difficulty Not Graded: N9d, V3,M9d, C2c, C8 Reviewing your test

Properties of Blood Vessels Arteries Arterioles Capillaries Venules Veins Elastic, low compliance, large diameter, low resistance vessels Variable Resistance vessels MAP = TPR x CO Exchange Wall = simple squamous endothelium No smooth muscle; cannot change diameter Capacitance vessels, high compliance, low pressure, valves for unidirectional flow

S 2 Receptors for other ligands Alpha receptors more common except in skeletal muscle arterioles which have more B2 receptors

Fig. 12.36 Adjust TPR to maintain MAP Match blood flow to metabolism of cells S 3 Fig. 12.36 Metabolic vasodilators No parasympathetic innervation of arterioles! Importance of basal “tone.” 12.36.jpg Three forms of local control: 1) Metabolic autoregulation, 2) flow autoregulation, 3) myogenic autoregulation

Figure 12.02 Arteries = 10% of Blood Volume Veins = 60% of Blood Volume Arterioles = Resistance vessels Capillaries = 5% of Blood Volume

S 5 Capillaries: Continuous, discontinuous, and fenestrated capillaries: Ex: brain liver endocrine glands Figure 12.38 Generate vasodilators and vasoconstrictors Arterioles: 1) Extrinsic control by hormones and nerves 2) Intrinsic (local) control by …..a) metabolic autoregulation, …..b) flow autoregulation, and …..c) myogenic autoregulation.

S 6 Capillary exchange by: Diffusion, vesicle transport, bulk flow, mediated transport

Diffusion is the most important mode of exchange of nutrients Fig. 12.40 Diffusion is the most important mode of exchange of nutrients 12.40.jpg

Figure 12.41 Colloids Crystalloids Bulk Flow S 8 = colloids (impermeable proteins) Bulk Flow

Cell Membrane: selectively permeable Capillaries: highly permeable except to proteins

S 10 Figure 12.42 Bulk Flow through aqueous channels and intracellular clefts Starling Forces Regulated by arterioles Net filtration = 4L/day Main difference in the Pulmonary circuit?

S 11 Fig. 12.43 Pc Pc 12.43.jpg Pc

Who Cares? Aunt Esther S 12 Cancer of the liver; Failure of hepatocytes to produce plasma colloids

S 13 Figure 12.41 Colloids Crystalloids Bulk Flow