Blood and Its Importance

Introduction

• Scientific advancements have allowed for the replacement of many body parts and systems.
• Blood is unique as it cannot be manufactured or synthesized.
• Blood is crucial for survival, with someone needing a transfusion every 2 seconds in the US.
• Annual demand: nearly 16 million pints in the US.

Blood Composition

• Connective Tissue: Blood is a connective tissue with living cells in a non-living matrix (plasma).
• Functions: Transports oxygen, nutrients, waste, hormones, regulates temperature, pH, and fluid volume, and protects against infection.

Blood Donation

• Process involves donation of approximately a pint of blood taking 20 minutes.
• Blood is tested, separated into parts, and sent to hospitals.

Blood Components

• Whole Blood: Consists of cells and cell fragments (formed elements), water, and dissolved molecules.
• Separation Process: Blood is separated in a centrifuge into:
  • Red Blood Cells (Erythrocytes): 45%, carry oxygen and carbon dioxide.
  • White Blood Cells (Leukocytes): <1%, defend against toxins and microbes.
  • Platelets: <1%, aid in clotting.
  • Plasma: 55%, 90% water, contains proteins, electrolytes, gases, hormones, waste.

Plasma Components

• Electrolytes: Charged ions that regulate pH and osmotic pressure, essential for muscle contraction and nerve function.
• Plasma Proteins: Include albumin, globulins (transport lipids, ions), gamma globulins (defense), fibrinogen (clotting).

Hemostasis

• Bleeding Control: Prevents excessive blood loss via a process called hemostasis.
• Steps:
  • Vasoconstriction reduces blood flow.
  • Platelets form a plug at injury site.
  • Fibrin threads reinforce the plug, forming a clot.
• Hemophilia: A disorder affecting clot formation, requiring frequent transfusions.

Blood Types

• Antigens: Glycoproteins on cells that indicate blood type (A, B, AB, O).
• Antibodies: Attack foreign antigens, leading to coagulation.
• Blood Type Compatibility:
  • Type A: A antigens
  • Type B: B antigens
  • Type AB: Both A and B antigens (universal recipient)
  • Type O: No antigens (universal donor)
• Rh Factor:
  • Rh-positive: Have Rh antigens
  • Rh-negative: Lack Rh antigens

Conclusion

• Blood is irreplaceable and complex, crucial for survival.
• Understanding blood types and hemostasis is important for transfusion safety.

Additional Information

• Crash Course: Information supported by Patreon patrons.
• Credits: Episode written by Kathleen Yale, directed and edited by Nicole Sweeney.