When contraction of the ventricle is completed, the ventricle relaxes, pressure falls in the ventricle, and aortic and pulmonic valves close. The sound of the blood hitting these just-closed valves creates the dup sound. The slowing of blood flow as blood enters the larger volume of the capillary bed and the thinner blood vessels no connective tissue or muscle cells, just endothelial cells on a basement membrane. Hydrophobic materials such as fatty acids and triglycerides move through the blood from tissue to tissue. The liver makes and secretes albumins and lipoproteins to the blood plasma.
Albumins carry fatty acids and other small hydrophobic molecules from tissue to tissue.
The lipoproteins, especially low density lipoproteins, carry larger lipids such as triglycerides, and cholesterol esters from tissue to tissue. The O 2 concentration in water is much lower than in air. Endothelial cells in post-capillary venules are induced by signaling molecules from a nearby infection to make cell adhesion molecules on their lumenal surface. When cell adhesion molecules cluster together, the adhesion of neutrophils to endothelium becomes stronger and the rolling stops. Neutrophils then insert themselves between adjacent endothelial cells, digest the basement membrane, and move by amoeboid-type motion into the infected tissues.