Blood and its properties

• Blood circulating in a mammal constitutes about 7.5% of its body mass.
• An average human weighing between 68-80 kgs has about 4.7 to 5 litres of blood in their body
• Blood can be considered as tissue because it contains millions of cells.
• These cells tend to be similar and they also perform similar functions:
• They carry out transport functions and protect the mammal disease
• Blood tissue is made up of a fluid called plasma
• Red and white blood cells float within this plasma
• Glucose and amino acid molecules are also found in the plasma in dissolved form

Functions of Blood

• Blood has several major functions.
• First it acts as a transport medium
• It carries substances around the body
• These substances include dissolved food, oxygen and plasma proteins which are all carried to where they are needed
• Blood also carries waste substances produced by the body cells to excretion organs such as lungs and kidneys
• Blood also helps with heat distribution from the internal organs to the fingers and toes
• Homeostasis-is the maintenance of temperature, water, salt and glucose levels at a constant optimum levels
• Blood plays a critical role in the homeostasis process
• The white blood cells attack foreign particles and germs( viruses and bacteria) which invade the mammal’s body
• The blood’s platelets are responsible for clotting of the blood where there is a wound or injury.
• They release enzymes which convert special plasma proteins into  a blood clot to stop the flow of blood.
• This prevents the mammal from dying as a result of excessive blood loss
• The clot also prevents the further entry of germs into the mammal’s body

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