Biology

About 5 litres

pH 7.4

Function:

• Transports
  • respiratory gases
  • nutrients
  • waste materials
  • hormones
  • enzymes
• regulates
  • body temperature
  • pH
• protects against
  • blood loss
  • foreign agents

Blood components:

Cellular elements:

1. Red blood cells / erythrocytes

• biconcave shape, disk (doughnut shape)
• 5-5.5 million / mm³
• sports and altitude increase the number
• 7μm
• lose nucleus during maturation -> can’t reproduce
• can’t move – only passively
• produced in red bone marrow (vitamin B₁₂)
• destroyed in liver, spleen (after 120 days)

Functions:

• transports oxygen -> haemoglobin in its cytoplasm
  • in lungs picks up oxygen -> oxyhemoglobin
  • in tissues O2 pressure is low -> releases oxygen
• transports CO₂

Disease:

• anaemia: low number of red blood cells / haemoglobin concentration; lack of vitamin B₁₂ , Fe, folic acid
• sickle-cell anaemia: inherited disease, abnormal haemoglobin, sickle shaped cells are stiff -> block blood flow, can cause pain, serious infections, and organ damage, leads to death.

• haemolysis: breakdown of red blood cells before time (poison of bees, snakes -> membrane damaged)

 2. White blood cells / Leukocytes

• variable shape
• amoeboid movement -> can leave capillaries -> site of infection
• 6-8000 / mm³
• 5-20μm
• have a nucleus
• produced in red bone marrow
• destroyed in liver (after 1- 2 weeks)

Function:

• immune response – combat microbes and their toxins

Types:                           

• granulocytes: leave to the site of infection – endocytosis -> die
• monocytes: (largest) leave to the site of infection – endocytosis -> die
• lymphocytes: mature in lymphatic tissue, recognize

Disease:

• leukaemia: many immature white blood cells <- abnormal bone marrow
• chemotherapy, irradiation to kill tumour cells, bone marrow transplantation
• 

3. Platelets / Thrombocytes

• 2-4μm
• 150-300 thousand / mm³
• fragments of the cytoplasm of large cells
• -> no nucleus
• produced in red bone marrow
• destroyed in liver, spleen (after 8-9 days)

Function:

• blood clotting:
  • platelets coagulate ( stick to rough surfaces) -> release chemicals
  • vessel constricts
  • clot formation: 13 protein factors

           activator complex

prothrombin -> thrombin (vitamin K, Ca²⁺)

            fibrinogen -> fibrin -> insoluble network of threads

clot soon begins to shrink -> forms a scab

Disease:

• haemophilia: inability to stop bleeding (many types)
• arteriosclerosis: rough surface of vessels -> clot formation

- > thrombus can block an artery

• in heart -> heart attack
• in brain -> stroke

-> can break loose (-> embolus) -> block smaller arteries

- in lungs -> pulmonary embolus

- in brain -> fainting, limb weakness

Risk factors: aging, smoking, high blood pressure, fats in blood, diabetes.

Learningapps practice here