Calcium Channel Blockers

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The walls of the arteries contain smooth muscle that contracts or relaxes to change their diameter. These changes modify the blood flow and strongly influence blood pressure. Blood pressure rises when the arteries constrict and falls when they relax and dilate. Excessive, widespread vasoconstriction can cause hypertension (high blood pressure), and vasoconstriction in the coronary blood vessels of the heart can cause pain (angina) due to inadequate blood flow to the cardiac muscle. In order to contract, a smooth muscle cell must open calcium channels in its plasma membrane and allow calcium to enter from the extracellular fluid. Drugs called calcium channel blockers prevent calcium channels from opening. Thus they help to relax the arteries, relieve angina, and lower blood pressure.

Chemical messenger

Breakdown products

Solute molecules \

Chemical messenger

Breakdown products

Solute molecules \

Physiology Cam
  • Receptor
  • Enzyme © Channel
  • Receptor
  • Enzyme © Channel

@ Motor molecule

@ Motor molecule

Cell-adhesion molecule (CAM)

Cell-adhesion molecule (CAM)

Figure 3.8 Some Functions of Membrane Proteins. (a) A receptor that binds to chemical messengers such as hormones sent by other cells. (b) An enzyme that breaks down a chemical messenger and terminates its effect on the target cell. (c) A channel protein that is constantly open and allows solutes to pass in and out of the cell. (d) A gated channel that opens and closes to allow solutes through only at certain times. (e) A motor molecule, a filamentous protein arising deeper in the cytoplasm that pulls on membrane proteins and causes cell movement. (f) A glycoprotein serving as a cell-identity marker. (g) A cell-adhesion molecule (CAM) that binds one cell to another.

Saladin: Anatomy & I 3. Cellular Form and I Text I © The McGraw-Hill

Physiology: The Unity of Function Companies, 2003 Form and Function, Third Edition

102 Part One Organization of the Body

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Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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