Grade 9 Biology: Blood Circulatory System Vocabulary

Vocabulary flashcards generated from Biology Grade 9 notes covering the blood circulatory system, components of blood, RBC adaptations, WBC types, and the immune system.

Human Circulatory System

The system responsible for circulating fluids throughout the body, consisting of three main parts: a pump (the heart), a system of tubes (blood vessels), and a circulating fluid (blood).

Heart

A very muscular organ situated in the chest, about the size of a clenched fist, whose function is to pump blood into blood vessels to all parts of the body.

Closed System

A type of circulatory system where blood flows continuously inside blood vessels.

Blood Volume (Adult)

An adult's body contains an average of about $5\text{ to }6\,\text{litres}$ of blood.

Plasma

The pale yellow liquid component of blood that makes up $55\%$ of blood volume, consisting of $90\%$ water and $10\%$ dissolved substances.

Dissolved Substances in Plasma

Substances carried in plasma, including useful substances such as nutrients (glucose, amino acids, fats), mineral ions, proteins, and hormones, as well as waste (excretory) substances such as urea and $CO_2$.

Blood Solids

The cellular portion making up $45\%$ of blood, composed of $41\%$ red blood cells and $4\%$ white blood cells.

Red Blood Cells (RBCs)

Very small, biconcave, disc-like cells made in the bone marrow that contain no nucleus and make up $41\%$ of blood cells.

RBC Quantity

There are about $5\,\text{million}$ RBCs in $1\,mm^3$ of blood.

Haemoglobin

A red pigment filling the cytoplasm of red blood cells that functions to absorb and carry oxygen.

RBC Lifespan

Red blood cells live for about $3\text{ to }4\,\text{months}$, after which they are destroyed in the liver.

RBC Nucleus Adaptation

The absence of a nucleus in RBCs provides more space inside the cell to accommodate more haemoglobin.

RBC Shape Adaptation

A disc-like (flattened), biconcave shape that provides a large surface area for transporting more oxygen and enables cells to squeeze through narrow blood capillaries to rapidly release oxygen at body tissues.

White Blood Cells (WBCs)

Nucleated blood cells that are larger and fewer in number than RBCs, forming the body's immune system to protect against diseases by killing germs.

Platelets

Fragments of large bone marrow cells found in the blood.

Immune System

A system which helps protect our body, keeps us healthy, and fights against germs.

Phagocyte

A type of WBC characterized by an irregular shape, lobed nucleus, and granular cytoplasm, which can move, change shape, and squeeze out through capillary walls to engulf and digest germs.

Lymphocyte

A type of WBC characterized by an oval shape, large nucleus, and little clear cytoplasm that produces proteins called antibodies.

Antibodies

Proteins produced by lymphocytes that destroy germs and neutralise their toxins.

Toxins

Poisonous secretions produced by germs.