What is in blood and where is it made?

Component

Function

Source

Gases

Required for metabolism

A waste product of metabolism

Component of other molecules

A vasodilator

Solvent

A fluid carrier for other components of the blood and a source of hydration for cells in the body.    

Small Molecules

Maintaining osmolarity, source of ions for cellular function. When overall salt levels are too high, this is sensed by the brain making us thirsty

Waste products from cells are transported in the blood for removal, principally by the kidneys and the liver. 

Source of energy

Required for cellular function and metabolism 

Ingested and absorbed through the digestive system. Skin (vitamin D)

Signalling Molecules

Messenger molecules can be proteins, such as insulin, or chemicals, such as thyroxin.  Examples of hormones include:

The development of female sex organs regulates the menstrual cycle. 

Development of male sex organs, musculature, and facial hair. 

Regulates blood sure levels. 

Regulates blood sure levels. 

Assists in blood pressure control. 

A precursor to triiodothyronine. 

Controls metabolic rate.

Block pain. 

Stimulates water retention by the kidneys. 

Major Blood Proteins

Serum Albumin is the major protein in plasma. Albumin binds to and transports hormones, fatty acids, and other compounds. Albumin buffers pH, and maintains oncotic pressure, among other functions. 

Produced in millions of different forms to recognize foreign proteins. 

An insoluble protein arranged in long chains. Enables clotting. 

A glycoprotein complex that is converted to fibrin during injury. 

Haemoglobin binds to oxygen to transport it from the lungs to other tissues in the body. Haemoglobin also transports about 75% of the carbon dioxide in the blood for exhalation. Haemoglobin is packaged in red blood cells to prevent it from wreaking oxidative havoc in the vasculature and exposed tissues. 

Lipids (Fats)

Important for building cell walls, making hormones, bile acids and vitamin D. Dangerous in excess contributing to heart disease.  Can be combined with proteins into Lipoproteins (See below)

Provide a stored source of energy between meals. Can be combined with proteins into Lipoproteins (See below)

Lipoproteins

(complexes of lipids and proteins)  

Carry triglycerides from the intestine.

Transport triglycerides made in the liver.

transport cholesterol made in the liver. This cholesterol is LDL-cholesterol. It is generally considered to be bad cholesterol.

Removes excess cholesterol away from artery walls and cells back to the liver for recycling and disposal. Generally considered good.

Extracelular Vesicles

Small hollow spheres of varying size with lipid walls containing protein and RNA cargo. Includes exosomes (50-200nm), microparticles (200 nm to 1 µm) generated by viable cells and apoptotic bodies generated by dying cells. Exosomes provide messenger function and are present at about 1x10¹² per ml. 

Platelets

Small, disc-shaped fragments that help to form clots in injured tissue. These are formed from the cytoplasm of megakaryocytes. They are found at a ratio of about 1 per 20 red blood cells and have a lifespan of 7-10 days.

Red Blood Cells

Make up about 40% of total blood volume. Their primary role is to provide a package for haemoglobin.

White Blood Cells

Present at a ratio of 1 white blood cell for every 600-700 red blood cells. Fight of infection and help to remodel damaged tissue. White blood cells are also called leukocytes

A type of white blood cell, further divided into individual cell types 

Fight infection and diseases such as cancer. 

Part of the innate immune system provides an initial response to infection by attacking virus-infected cells. 

Adaptive immune cells produce antibodies against pathogens. 

Most prevalent lymphocytes account for about 50% of the total. Phagocytic cells that ingest pathogens.

Phagocytic cells that ingest pathogens. Move from blood into inflamed tissue where they differentiate into macrophages which can orchestrate immune response and tissue remodelling. 

Kill parasites, destroy cancer cells, and are involved in allergic responses. 

Participate in allergic responses

Probably wrong to classify them as white blood cells as they are not primarily found in the blood. Macrophages are phagocytic cells that can originate in the tissues where they are found (tissue-resident macrophages) and also differentiate from monocytes after they have extravasated from the blood through the blood capillary walls into tissues.