Notes on Circulation and Blood Vessels

Objectives for Circulation and Blood Vessels

• Trace the path of cardiopulmonary circulation.
• Name and describe specialized circulatory systems.
• Trace the blood in fetal circulation.
• List types of blood vessels.
• Identify principal arteries and veins of the body.
• Describe disorders of circulation and blood vessels.
• Define key concepts related to circulation and blood vessels.

Key Terms

• Aneurysm: Balooning of an artery due to wall thinning.
• Arteries: Vessels that carry oxygenated blood away from the heart (excluding pulmonary arteries).
• Veins: Vessels that carry deoxygenated blood towards the heart.
• Capillaries: Smallest blood vessels where exchange occurs.
• Cardiopulmonary Circulation: Movement of blood between the heart and lungs.
• Systemic Circulation: Movement of blood from the heart to the body and back.
• Portal Circulation: Directs blood from digestive organs to the liver.
• Fetal Circulation: Circulation in a fetus receiving oxygen and nutrients from maternal blood.
• Hypertension: High blood pressure; risk factor for several diseases including stroke.

Circulatory Systems

1. Cardiopulmonary Circulation:

   • Blood flows from the heart to the lungs (to receive oxygen) and back to the heart.
   • Blood enters through the right atrium -> right ventricle -> pulmonary artery -> lungs (gas exchange) -> pulmonary veins -> left atrium -> left ventricle -> aorta.

2. Systemic Circulation:

   • Blood is distributed from the heart to all body cells and returns.
   • Functions include transporting nutrients, removing wastes, regulating temperature, and protecting from pathogens.

3. Specialized Circulatory Systems:

   • Coronary Circulation: Blood for heart muscle.
   • Portal Circulation: Blood from digestive organs to the liver.
   • Fetal Circulation: Utilizes umbilical cord, includes foramen ovale (between atria) and ductus arteriosus, which shunt blood away from the lungs and liver of the fetus.

Types of Blood Vessels

• Arteries:
  • Thick, elastic walls.
  • Three layers: tunica externa, tunica media, tunica intima.
  • Major arteries include the aorta, coronary arteries, and common carotid arteries.
• Capillaries:
  • Connect arterioles and venules.
  • Site of exchange of oxygen, nutrients, and waste products.
• Veins:
  • Thinner, less elastic walls; carry deoxygenated blood.
  • Composed of layers similar to arteries but with less muscle.
  • Contain valves to prevent backflow.

Blood Pressure

• Defined as the force of blood against vessel walls:
  • Systolic BP: Pressure during heart contractions (average 120 mm Hg).
  • Diastolic BP: Pressure when the heart relaxes (average 80 mm Hg).
• Influenced by blood volume, cardiac output, viscosity, vessel elasticity, and peripheral resistance.
• High blood pressure (hypertension) is a significant health risk, often requiring management through lifestyle changes and medication.

Common Disorders of Circulation

1. Aneurysms: Bulging vessels that can rupture.
2. Arteriosclerosis: Hardening and thickening of arteries with age.
3. Atherosclerosis: Fat deposits clog arteries.
4. Hypertension: Increased blood pressure affecting organ function.
5. Peripheral Vascular Disease (PVD): Blocked arteries, especially in legs, causing pain.
6. Cerebrovascular Accident (Stroke): Sudden loss of blood supply to the brain, classified as ischemic (clots) or hemorrhagic (bleeding).
7. Phlebitis: Inflammation of veins, often associated with thrombosis.

Nursing and Patient Care

• In managing circulatory issues, nurses play critical roles in monitoring blood pressure, educating patients about lifestyle changes, and assessing for signs of stroke or venous disorders.

Related Body System Interactions

• This circulatory system interacts with multiple body systems (e.g., respiratory, endocrine, and nervous systems) to maintain homeostasis and support bodily functions.