A&P LAB CIRCULATORY & CARDIOVASCULAR PHYSIOLOGY 02/03/25

Blood Flow and Blood Pressure Measurement

• Blood flow can be affected by external pressure on the blood vessels, particularly the brachial artery.

• Systolic Pressure: The first sound heard while releasing pressure from a cuff, indicating blood flow during ventricular systole.

• Diastolic Pressure: The point when the sounds stop, indicating continuous blood flow during diastole.

• Auscultation involves listening for blood flow sounds which are created by the valves closing, and this requires practice and proper equipment.

Understanding the Cardiovascular System

Arteries and Veins

• Arteries carry blood away from the heart, while veins return it.

• Differences between the right and left vessels due to their origins, e.g., right common carotid vs. left common carotid (originating from the aorta).

Key Arteries of the Aorta

1. Ascending Aorta: Initial section where blood is ejected from the left ventricle.

2. Aortic Arch: Curves and branches into major vessels.

3. Branches off the Aortic Arch:

   • Brachiocephalic Trunk: Divides into right common carotid and right subclavian arteries.

   • Left Common Carotid Artery: Directly branches off the aorta.

   • Left Subclavian Artery: Supplies blood to the left arm.

Brachial and Radial Arteries

• Brachial Artery: Continuation from the axillary artery; bifurcates into radial and ulnar arteries at the elbow.

• Radial and Ulnar Arteries: Supply the forearm and wrist, forming the superficial palmar arch which supplies fingers.

Head and Neck Circulation

• Common Carotid Arteries: Supply blood to the head and neck; bifurcate into internal (to skull) and external (to face) carotid arteries.

• Jugular Veins: Return blood from the brain and face

The Circle of Willis and Brain Blood Supply

• Circle of Willis: An important arterial circle at the base of the brain.

  • Formed by internal carotids and vertebral/basilar arteries;

  • Supplies 80% of brain blood flow.

• Branches of the Circle:

  • Anterior Cerebral Arteries: Supply the front portion of the brain.

  • Middle Cerebral Arteries: Supply lateral parts of the brain.

  • Posterior Cerebral Arteries: Supply the back of the brain.

  • Communicating Arteries: Connections between main arteries enhance blood flow efficiency.

Pulmonary Circulation

• Pulmonary Trunk: Carries deoxygenated blood from the right ventricle to the lungs.

  • Splits into right and left pulmonary arteries.

  • Oxygenated blood returns through pulmonary veins to the left atrium.

Abdominal Aorta Branches

1. Celiac Trunk: Supplies stomach, spleen, and liver; trifurcates into gastric, splenic, and hepatic arteries.

2. Superior Mesenteric Artery (SMA): Supplies small and part of the large intestine.

   • Compromised SMA blood flow can result in significant health risks, including necrosis of intestinal tissue.

3. Renal Arteries: Supply the kidneys.

4. Gonadal Arteries: Testicular in males, ovarian in females.

5. Inferior Mesenteric Artery: Supplies the rest of the large intestine.

6. Common Iliac Arteries: Final branches of abdominal aorta, further bifurcating into internal and external iliac arteries.

Blood Circulation in the Lower Extremities

• Femoral Artery: Continuation of the external iliac artery; pulses can be palpated.

• Popliteal Artery: Located behind the knee, it branches into the anterior and posterior tibial arteries.

• Dorsalis Pedis Artery: The continuation of the anterior tibial artery; often checked for pulse in peripheral vascular examination.

Clinical Significance of Blood Vessels

• Great Saphenous Vein: Commonly harvested for bypass grafts.

• Blood Pressure Measurement: Accuracy can differ based on the site (e.g., wrist readings may be inaccurate).

  • Understanding the anatomy helps in proper palpation and auscultation techniques.