The Circulatory System

Vocabulary terms covering the components, functions, and cellular makeup of the human circulatory system.

Circulatory System

Also known as the cardiovascular system, it is the transport system of the body that carries nutrients, dissolved gases such as $O_2$ and $CO_2$, wastes, antibodies, and hormones.

Three general components of the Cardiovascular System

1. A fluid to transport material (eg, blood). 2. A system of vessels or spaces (e.g., arteries and veins). 3. A pump that pushes the fluid (e.g., the heart).

Blood Volume and Body Mass

In an average $70\,kg$ individual, there is about $4-5\,L$ of blood, which accounts for approximately $8\%$ of total body mass.

Plasma

The liquid portion of blood that makes up approximately $55\%$ of its volume, containing $90\%$ water, proteins, and other dissolved components like ions and sugars.

Albumin

A plasma protein responsible for maintaining fluid volumes.

Globulins

Plasma proteins that act as transport proteins and antibodies.

Fibrinogen

A specific plasma protein that assists in the process of blood clotting.

Erythrocytes

Blood cells that contain hemoglobin to carry $O_2$ around the body; they make up part of the $45\%$ cellular component of blood.

Hemoglobin

The molecule within red blood cells that transports oxygen; without it, a human would only have enough oxygen to live for $4.5$ seconds.

Leukocytes

Also known as white blood cells, these protect the body against invading microorganisms and toxins by engulfing them or producing antibodies.

Platelets

Small, irregularly shaped fragments of larger cells produced in the bone marrow whose primary function is to initiate blood clotting.

Fibre mesh

A structure created when platelets rupture upon encountering a rough edge, which prevents blood flow and closes wounds.

Pus

A substance that contains dead leukocytes.

Blood vessel distance rule

No blood cell in the body is farther than $2$ cells away from a blood vessel that carries nutrients.

Total blood vessel length

There are over $100,000\,km$ of blood vessels in the human body.

Blood cell lifespan

Blood cells typically live for about $3-4$ months.