Blood Vessels and Circulation

CIRCULATORY SYSTEM

  • Overview: The circulatory system's blood vessels form a complex network that resembles an interstate highway system.

Functions of Blood Vessels

  • Carries Blood: Transports blood from the heart to body tissues and back.
  • Exchanges Substances: Nutrients and oxygen diffuse from blood vessels to cells.
  • Transports Various Substances: Includes hormones, immune components, molecules for clotting, enzymes, gases, and waste products.
  • Regulates Blood Pressure: Works in tandem with the heart to maintain normal blood pressure (e.g., the highest normal is 120/80120/80).
  • Directs Blood Flow: Adjusts blood flow to tissues to maintain homeostasis based on demand.

General Features of Blood Vessel Structure

Arteries
  • Function: Carry blood away from the heart, typically oxygenated.
  • Structure Transition: From elastic tissues in large arteries to more smooth muscle in smaller arteries.
Types of Arteries
  1. Elastic Arteries:
    • Large diameter and thick walls.
    • More elastic tissue than smooth muscle.
    • Examples: Aorta, pulmonary trunk.
  2. Muscular Arteries:
    • Medium-sized, thicker walls relative to diameter.
    • Comprised mostly of smooth muscle cells.
Key Terms
  • Vasoconstriction: Contraction causing decreased diameter and blood flow.
  • Vasodilation: Relaxation leading to increased diameter and blood flow.
  • Arterioles: Small arteries transitioning into capillaries with one or two layers of smooth muscle.
Capillaries
  • Function: Site of exchange for oxygen, carbon dioxide, nutrients, and waste between blood and tissue fluid.
Veins
  • Function: Transport blood towards the heart, generally deoxygenated.
  • Structure: Thinner walls than arteries, less elastic tissue, and smooth muscle.
Types of Veins
  • Venules: Slightly larger than capillaries,structure includes endothelium on connective tissue.
  • Small and Medium Veins: Collect blood from venules to larger veins.
  • Large Veins: Diameter greater than 2 mm, contain valves to direct blood flow towards the heart.

Types of Circulation

Pulmonary Circulation
  • Transports blood from the right ventricle to the lungs and back to the left atrium.
Systemic Circulation
  • Carries blood from the left ventricle to the body tissues and back to the right atrium.

Aorta Sections

  1. Ascending Aorta: Emerges from the left ventricle.
    • Supplies coronary arteries to the heart.
  2. Aortic Arch: Gives rise to major arteries (e.g., Brachiocephalic, Left Common Carotid, Left Subclavian).
  3. Descending Aorta: Longest section extending through thorax/abdomen to pelvis.

Arterial Aneurysm

  • Localized dilation of an artery, risk of rupture, which may be fatal.

Blood Vessels of the Systemic Circulation: Arteries

Major Arteries in Head and Neck
  • Brachiocephalic Artery: First branch of aortic arch on the right.
  • Common Carotid Arteries: Supply blood to head and neck, split into internal (to brain) and external (to face).
  • Vertebral Artery: Supplies brain and spinal cord.
Major Arteries of the Upper Limbs
  • Axillary, Brachial, Ulnar, and Radial Arteries: Supply blood to arm and hand; radial used for pulse check.
Arteries of the Thorax
  • Thoracic Aorta Branches: Supply thoracic organs.
Abdominal Aorta and its Branches
  • Supplies major abdominal organs (stomach, liver, intestines) via celiac trunk, superior/inferior mesenteric arteries.
Arteries of the Lower Limbs
  • Femoral, Popliteal, and Tibial Arteries: Supplies blood to legs and feet.

Blood Vessels of the Systemic Circulation: Veins

Major Veins
  • Superior and Inferior Vena Cava: Return deoxygenated blood to the right atrium from upper and lower body respectively.
Veins of the Head and Neck
  • External/Internal Jugular Veins: Drain blood from various regions of the head and neck.
Veins of the Upper Limbs
  • Deep and Superficial Veins: Follow artery patterns, carry blood back to heart.
Veins of the Abdominal and Pelvic Region
  • Hepatic Portal System: Connects capillary beds of intestines to liver for filtering.
Veins of the Lower Limbs
  • Great and Small Saphenous Veins: Major superficial veins of the leg.

SAFETY AND INFECTION CONTROL

Disease Types

  • Nosocomial Diseases: Acquired in hospital settings; Infection control is critical.
  • Communicable Diseases: Can lead to outbreaks with severe health implications (e.g., cholera, tuberculosis).
  • Vaccine-Preventable Diseases: Diseases preventable by vaccines (e.g., polio, measles).

Cycle of Infection

  • Pathogen: Organism causing the infection.
  • Host: Infected individual.
  • Transmission Factors: Environment, climate, human activity affecting disease spread.

Infection Control Practices

  • Medical Asepsis: Clean technique to reduce pathogen transmission.
  • Surgical Asepsis: Sterile technique for procedures involving open wounds.

Personal Protective Equipment (PPE)

  • Gloves: Protect healthcare workers from infectious agents.
  • Masks and Respirators: Prevents respiratory pathogen transmission.
  • Goggles/Face Shields: Protect against droplet transmission.

Safe Practices

  • Hand Hygiene: Essential for preventing microorganism spread.

  • Proper Use of PPE: Ensure safety during patient contact to reduce infection risk.

  • Reporting Injuries: Procedures in place for needle stick injuries should be followed immediately.