Glossary

adipose

Also known as fat tissue, is a specialised type of connective tissue that serves several functions in the body. Its primary role is to store energy in the form of fat, but it also provides insulation and protection for organs.

actin

Actin is a family of globular, multi-functional proteins that form microfilaments, one of the three major components of the cytoskeleton in eukaryotic cells. Actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the maintenance of cell junctions and cell shape.

antagonist

An antagonist is a molecule that blocks or inhibits the action of an agonist at a receptor, preventing a biological response.

astrocytes

Type of glial cell found in the central nervous system, particularly in the brain and spinal cord. They are the most abundant glial cells in the brain and play a vital role in maintaining the health and proper functioning of the nervous system.

autocrine signals

The signalling cell can also bind to the ligand being released enabling signalling to the same or a similar cell.

autocrine signalling

Form of cell signalling in which a cell secretes a molecule, such as a hormone or growth factor, that binds to receptors on the same cell, leading to changes in the cell. Essentially, the cell targets itself, and the signalling molecule affects the cell that produced it.

autoinducers

Signalling molecules secreted by bacteria to communicate with other bacteria of the same kind.

autorhythmic

Ability of certain cells to generate a rhythm or regular pattern of electrical activity spontaneously.

axon

Specialised extension of a neuron that conducts electrical impulses away from the neuron’s cell body towards other neurons or effector cells, such as other neurons, muscles or glands.

basement membrane

Thin, fibrous, extracellular matrix of tissue that separates the lining of an internal or external body surface (such as epithelial or endothelial tissue) from underlying connective tissue.

basophils

Least common type of white blood cell, or leukocyte, making up less than 1% of the total leukocyte population in the blood. Despite their rarity, basophils play important roles in the immune system, particularly in the response to allergies and parasites.

biofilms

A colony of bacteria attached to a biotic or abiotic surface enclosed within a matrix of extracellular polymeric substances produced by the colony.

canaliculi

Singular: canaliculus, are tiny, microscopic channels or passageways in the bone matrix that connect lacunae, the small cavities that house the bone cells (osteocytes), to each other and to the central Haversian canal in an osteon.

carbohydrates

Biological macromolecule in which the ratio of carbon to hydrogen and to oxygen is 1:2:1; carbohydrates serve as energy sources and structural support in cells and form arthropods’ cellular exoskeleton.

cartilage

Type of firm, flexible connective tissue found in various parts of the body. It is less rigid than bone but more rigid than muscle, and its primary function is to provide support, but unlike bone, cartilage can bend a bit.

cell membrane

An antagonist is a molecule that blocks or inhibits the action of an agonist at a receptor, preventing a biological response.

chemical synapse

Chemical signal is released from a neurotransmitter to communicate with target neuron.

chemotaxis

Chemotaxis is a biological process in which cells or organisms move in response to a chemical stimulus. The movement can be either toward (positive chemotaxis) or away from (negative chemotaxis) the source of the chemical signal.

chondrocytes

Cartilage cells.

chronic

Health condition or disease that persists over a long period of time.

collagen

Key structural protein that forms the connective tissue throughout our body, from skin to bones, muscles, tendons, and ligaments.

columnar epithelial

Tall and narrow shaped epithelium cells, with the nucleus located toward base.

connective tissues

One of the four basic types of tissue found in the body. Serves a “connecting” or supportive role, binding, supporting, protecting, and insulating various other tissues and organs in the body.

cuboidal epithelial cells

Cube shaped epithelium cells with a central nucleus.

cystic fibrosis

Cystic fibrosis (CF) is a genetic disorder that affects mainly the lungs, but also the pancreas, liver, kidneys, and intestine. It is caused by mutations in the CFTR gene, which encodes a protein called the cystic fibrosis transmembrane conductance regulator.

dendrites

Branched extensions of a neuron that act as the main information receivers for the cell.

depolarised

Depolarisation is a term used in biology to describe a change in a cell’s membrane potential, specifically the voltage inside the cell when compared to voltage outside of the cell. Depolarisation occurs when the intracellular environment becomes more positively charged (less negative). It’s a crucial process in the functioning of nerve and muscle cells.

diffusion

Movement of molecules along the concentration gradient.

DNA

‘Deoxyribonucleic acid’. Contains genetic information for cell function, growth and division.

down-regulation

Reduction in the number of cell-surface receptors to reduce or suppress the cells response to stimulus.

efflux pumps

Membrane proteins found in the cell membranes of both prokaryotic and eukaryotic cells. They play a vital role in transporting various substrates, including ions, drugs, and metabolic products, out of the cell or into specific compartments within the cell.

elastic cartilage

Also known as yellow cartilage, is named “elastic” because of its high content of elastic fibres, which gives it both flexibility and resilience.

elastic fibres

Type of connective tissue composed of the proteins elastin and fibrillin. These fibres provide strength and flexibility to tissues and allow them to return to their original shape after being stretched or contracted.

electrical synapse

Direct connection between neurons allowing movement of ions from one cell to the next via gap junctions.

endocrine

System of glands and hormones that regulate many of the body’s key functions by releasing hormones directly into the bloodstream. The endocrine system is vital for maintaining homeostasis and orchestrating complex physiological processes throughout the body.

endocrine signalling

Type of intercellular communication that involves the secretion of hormones by endocrine glands into the bloodstream.

endocrine signals

Signalling molecule (hormone) enters the blood stream to signal a distant cell with a receptor specific to the signalling molecule.

endothermic

Endothermic organisms are those that can regulate their body temperature by producing heat metabolically and by insulating the body to reduce heat loss.

eosinophils

Type of white blood cell, or leukocyte, and are part of the body’s immune system. They make up about 1-6% of the white blood cells in the bloodstream and are one of the types of cells classified as granulocytes, along with neutrophils and basophils.

epithelial tissues

Also known as epithelium, it is one of the four main types of tissue in animals. It covers surfaces both internally and externally.

EPS

Organic polymers synthesised by microorganisms involved in colony aggregation as a biofilm and important for bacterial interactions with their environment.

erythrocytes

Red blood cells (RBCs).

eukaryotic

Plants, animals, protozoans, algae and fungi.

excitable cells

Specialised cells that have the ability to generate and propagate electrical signals known as action potentials.

exocellular

Anything located or occurring outside a cell.

extracellular matrix

Three-dimensional network of proteins and molecules that surround cells to give structure and provide support.

extracellular polymeric substance (EPS) matrix

Organic polymers synthesised by microorganisms involved in colony aggregation as a biofilm and important for bacterial interactions with their environment.

fibroblasts

Main cell of connective tissue, responsible for producing fibres.

fibrocartilage

Type of cartilage that contains a high proportion of collagen fibres, which gives it significant tensile strength and rigidity. It’s less compressible and more dense than other types of cartilage (hyaline and elastic cartilage), which makes it particularly well-suited for areas of the body that require a high degree of support or must withstand heavy pressure.

fibrous connective tissues

Type of connective tissue in the body that is composed of parallel bundles of collagen fibers, which give it high tensile strength, i.e., the ability to resist being pulled apart.

gap junctions

Specialised intercellular connections that allow direct communication between the cytoplasm of adjacent cells. They enable various molecules, ions, and electrical impulses to pass directly from one cell to an adjacent cell, facilitating coordination and synchronization of activities among connected cells.

genes

Functional length of DNA that provides the genetic information necessary to build a protein.

glia

Glial cells, or simply glia, are non-neuronal cells found in the central nervous system (brain and spinal cord) and the peripheral nervous system. They play several crucial supportive roles in the nervous system, maintaining homeostasis, forming myelin, and providing support and protection for neurons.

ground substance

Nonliving substance made of organic and inorganic substances, typically giving a gel-like consistency.

hormones

Secretion of an endocrine organ that travels via the bloodstream or lymphatics to induce a response in target cells or tissues in another part of the body.

hyaline cartilage

Type of connective tissue that provides support and flexibility to different parts of the body. It has a glossy, glass-like appearance when cut and viewed under a microscope.

hydrophobic

Property of a molecule to be repelled by, or not having an affinity for, water.

ions

Positively or negatively charged atom or molecule.

intercalated disc

Specialised structures found between the cells (myocytes) of cardiac muscle tissue. They represent complex junctional complexes that are responsible for linking adjacent cardiac muscle cells together, facilitating the coordinated contraction of the heart.

intercellular signalling

Communication from one cell to another.

intracellular signalling

Communication within a cell, usually triggered in response to extracellular stimulation.

kinases

Type of enzyme that catalyses the transfer of a phosphate group from a high-energy molecule, such as adenosine triphosphate (ATP), to a specific target molecule, typically a protein. This process is known as phosphorylation.

lacunae

Term used in biology to refer to the small spaces or cavities within the hard matrix of bone and cartilage where cells reside.

lipid

Macromolecule that is nonpolar and insoluble in water.

leukocytes

Also known as white blood cells, are a key part of the immune system.

ligand

A chemical messenger molecule that irreversibly binds a specific protein receptor to form a complex.

lymphocytes

Type of white blood cell that are fundamental to the immune system. They are responsible for immune responses that provide long-term protection against pathogens.

macrophages

Type of white blood cell in the immune system that play several roles in the body’s defence against disease. This name reflects their function as phagocytes, cells that can engulf and digest cellular debris, foreign substances, microbes, cancer cells, and anything else that does not have the types of proteins specific to healthy body cells on its surface, in a process called phagocytosis.

matrix

Typically refers to the extracellular matrix (ECM), a three-dimensional network of extracellular macromolecules such as collagen, enzymes, and glycoproteins that provide structural and biochemical support to surrounding cells.

membranes

Selectively permeable barrier that separates the interior of a cell from its external environment.

microglial cells

Microglial cells, or simply microglia, are a type of glial cell located throughout the brain and spinal cord. They are the resident macrophages of the central nervous system (CNS) and play a critical role in immune defence, inflammation, and maintenance of homeostasis within the CNS.

mitochondria

Large, complex organelles in which aerobic cellular respiration occurs in eukaryotic cells. Often referred to as the ‘powerhouse’ of the cell.

monocyte

Type of white blood cell, or leukocyte, that play a crucial role in the body’s immune system. They are the largest type of leukocyte and make up about 2-10% of the total leukocyte population in the human body.

mucosa

Mucosa (plural: mucosae) refers to the moist tissue layer that lines certain parts of the inside of the body. It forms the innermost layer of certain organs and body cavities and serves various functions depending on its location.

myosin

Family of motor proteins found in eukaryotic tissues that is best known for its role in muscle contraction. It functions by interacting with another protein called actin, and together, myosin and actin are responsible for producing the force and movement seen in muscle cells.

neuron

Also known as a nerve cell, is the fundamental unit of the nervous system, responsible for transmitting information throughout the body. Neurons are electrically excitable cells that function to process and transmit information through electrical and chemical signals.

neurotransmitter

Chemical substance that transmits signals across a synapse from one neuron (nerve cell) to another “target” neuron, muscle cell, or gland cell.

nuclei

Found in eukaryotic cells and contains the DNA genome.

nucleus

Membrane-bound organelle found in most eukaryotic cells, often considered the control center of the cell because it houses the cell’s genetic material, DNA (deoxyribonucleic acid).

oligodendrocytes

Type of glial cell found in the central nervous system (CNS), including the brain and spinal cord. They play a crucial role in supporting and insulating neurons by forming the myelin sheath.

paracrine signalling

Type of cell-to-cell communication in which a cell produces a signal to induce changes in nearby cells, altering the behaviour or differentiation of those cells.

paracrine signals

Signalling molecule diffuse through extracellular matrix and target nearby cells.

peptide

Short chain of amino acids linked together by peptide bonds. Peptides are smaller than proteins and can be thought of as small proteins or protein fragments. The distinction between peptides and proteins is somewhat arbitrary, but peptides are generally considered to contain fewer than 50 amino acids.

peripheral

Situated on the outer limits or edge.

phagocytose

Immune cell that surrounds, ingests and destroys foreign material.

phagocytosis

Immune cell that surrounds, ingests and destroys foreign material.

phenotypic

Set of observable characteristics, such as height, eye colour.

planktonic

Free-swimming, unicellular bacteria.

plasma

Liquid component of blood in which the blood cells are suspended in. Primarily consists of water, but also contains other substances such as proteins, hormones, nutrients, etc.

plasma membrane

Selectively permeable barrier that separates the interior of a cell from its external environment.

platelets

Also known as thrombocytes, are small, colourless cell fragments in our blood that form clots and stop or prevent bleeding.

polymeric

Polymeric refers to a structure that is made up of smaller, repeating units called monomers, which are covalently bonded together in a chain-like structure to form a larger, more complex molecule known as a polymer.

osseous

Refers to anything related to, composed of, or resembling bone.

osteoblasts

Cells responsible for the formation of new bone, a process known as ossification. Osteoblasts secrete a matrix of organic compounds, including collagen, which provides a framework for bone growth.

osteoclasts

Large, multinucleated cells that are responsible for the breakdown and resorption of bone tissue, a process known as bone resorption.

osteocytes

Mature bone cells that originate from osteoblasts.

osteons

Also known as a Haversian system, is the primary structural unit of compact, or cortical, bone.

prokaryotic

Archaea and bacteria.

proteins

Biological macromolecule comprised of one or more amino acid chains.

quorum sensing

Communication between bacteria cells about cell population density that bacteria can then respond to by adjusting gene expression within the cell.

receptors

Proteins either on the cell surface or inside a target cell that bind to a specific ligand and receives chemical signal.

signalling cells

Cells that release chemical signals in the form of ligands.

simple epithelia

Single layer of cells.

squamous epithelial

Flat, irregular, slightly rounded shape of epithelial cells.

stratified epithelia

Multiple layers of cells staggered on top of one another.

striations

Pattern of stripes visible under the microscope, primarily in skeletal and cardiac muscle tissues. These striations are caused by the arrangement of contractile proteins, mainly actin and myosin, within the muscle cells.

symbiotic

Symbiosis refers to a close and often long-term interaction between two or more different biological species.

target cells

Cells that are affected by the chemical signals sent from signalling cells.

trabeculae

Lattice-like network of bony spicules that form the structural units of spongy (cancellous) bone.

transitional

Rounded epithelium cells arranged in simple layers, but appear stratified.

triglycerides

Fat molecule; consists of three fatty acids linked to a glycerol molecule. Also Triacylglycerol.

upregulated

Increase in the number of cell-surface receptors to increase the cells response to stimulus.