BZ 110 Lecture Notes - Lecture 1: Phagocyte, Cell Membrane, Pinocytosis
Document Summary
Molecules spread out randomly from areas of higher concentration to areas of lower concentration. Carrier proteins in a plasma membrane temporarily bind with molecules and help them pass across the membrane. Other proteins form channels through which molecules move across the membrane. Water molecules diffuse across selectively permeable membranes from areas of higher concentration to areas of lower concentration. Essentially protein- free plasma moves across capillary walls due to a pressure gradient across the wall containing oxygen, which moves into the lungs and the diffuses into the bloodstream. Glucose in the gut of a frog combines with carrier proteins to pass through the gut cells into the bloodstream. Water molecules move into a frog"s red blood cell when the concentration of water molecules outside the blood cell is greater than the inside. A frog"s blood pressure forces water and dissolved wastes into the kidney tubules during urine formation.
