JG

Cardiovascular System: Vessels and Circulation Vocabulary//STUDIED

Blood Vessels Anatomy

  • Arteries: Carry blood away from the heart.
  • Arterioles: Smallest artery branches.
  • Capillaries: Site of diffusion between blood and interstitial fluid.
  • Venules: Collect blood from capillaries.
  • Veins: Return blood to the heart.

Vessel Wall Structure

  • Tunica Intima: Innermost layer; includes endothelial lining.
  • Tunica Media: Middle layer; contains smooth muscle.
  • Tunica Externa: Outer layer; connective tissue.

Artery vs. Vein Differences

  • Artery walls are thicker.
  • Arteries have smaller, round lumens; veins have larger, flat lumens.
  • Veins contain valves.

Arteries

  • Contractility: Allows diameter change.
    • Vasodilation: Lumen enlargement.
    • Vasoconstriction: Lumen reduction.
  • Elastic Arteries: Large vessels that transport large volumes of blood away from the heart.
  • Muscular Arteries: Medium-sized distribution arteries with more muscle cells.
  • Arterioles: Control resistance; called resistance vessels.
  • Aneurysm: Weakening in artery wall leading to bulging. Risk of rupture.

Capillaries

  • Exchange site in capillary networks.
  • Diameter is about 8 micrometers.
  • Form capillary beds between arterioles and venules.
  • Collateral Arteries: Allow circulation if one capillary is blocked.
  • Arteriovenous Anastomoses (AV Anastomoses): Direct connections between arterioles and venules, bypassing the capillary bed.

Veins

  • Thinner walls, larger diameter than arteries.
  • Venous Valves: Prevent backflow.
  • Skeletal muscles compress veins, pushing blood toward the heart.

Blood Distribution

  • Heart, arteries, and capillaries hold 30-35% of blood.
  • Venous system holds 60-65%.
  • Venous constriction forces blood into arterial side during hemorrhaging.

Special Circulation

  • Brain: Cerebral vessels dilate when peripheral vessels constrict.
  • Heart: Coronary arteries dilate with low oxygen or high lactic acid.
  • Lungs: Pulmonary vessels dilate with increased oxygen levels.

Pulmonary Circuit

  • Deoxygenated blood goes to lungs via pulmonary arteries.
  • Oxygenated blood returns to heart via pulmonary veins.

Systemic Circuit - Arteries

  • Ascending Aorta: Aortic sinus with branching off of coronary arteries
  • Aortic Arch:
    • Brachiocephalic trunk: To brachium and head.
      • Right subclavian – to right arm
      • Right common carotid – to head
    • Left common carotid artery – to head
    • Left subclavian artery – to left arm
  • Common Carotid Arteries: Blood supply to the brain.
    *External carotid artery – supplies tissues outside of the cranium
    *Internal carotid artery – supplies tissues inside the cranium; Interruption of blood flow to brain tissue results in a cerebrovascular accident (CVA) or stroke
  • Descending Aorta: Divided by the diaphragm
    *Thoracic aorta:
    *Visceral branches supply the organs of the chest
    *Parietal branches supply the chest wall
    *Abdominal aorta:
    *Major branches to visceral organs (like spleen, liver, etc.) are unpaired
    *Branches to the body wall, kidneys, urinary bladder, gonads, etc. are paired

Systemic Circuit - Veins

  • Superior Vena Cava: Returns blood from head, neck, and upper extremities.
  • Inferior Vena Cava: Returns blood from the lower body.

Hepatic Portal System

  • Connects two capillary beds; hepatic portal vein delivers nutrient-laden blood to the liver.

Fetal Circulation

  • Umbilical Arteries: Carry blood to the placenta.
  • Umbilical Vein: Drains into the inferior vena cava.
  • Foramen Ovale → Fossa Ovalis
  • Ductus Arteriosus → Ligamentum Arteriosum

Aging - Cardiovascular System Changes

  • Blood: Decreased hematocrit, blood clots, blood pooling.
  • Heart: Decreased cardiac output, reduced elasticity, atherosclerosis.
  • Blood Vessels: Decreased elasticity, aneurysm, calcium deposits, atherosclerosis.