Cell Communications

Homeostasis

The maintenance of a stable internal environment in an organism.

Ligand

A molecule that binds to a receptor, triggering a response inside the cell.

Target Cells

Cells that receive and respond to signals from ligands.

Direct Contact Signaling

Cell communication where ligands pass between cells via direct contact.

Paracrine Signaling

Signaling where a cell sends signals to nearby cells.

Autocrine Signaling

When a cell produces a signal that binds to its own receptors.

Endocrine Signaling

Hormonal signaling where hormones are released into the bloodstream to reach distant target cells.

Signal Transduction

The process by which a signal is transmitted through the cell to produce a response.

Reception Phase

The phase where a ligand binds to its receptor and activates relay molecules.

Transduction Phase

The phase involving activation of relay molecules or kinases, propagating the signal.

Relay Proteins

Proteins that transmit signals from receptors to target molecules within the cell.

Kinases

Enzymes that activate other proteins by adding phosphate groups to them.

G-Protein Coupled Receptors (GPCR)

Membrane receptors that activate G proteins in response to signaling molecules.

Tyrosine Kinase Receptors

Membrane receptors that dimerize and phosphorylate each other in response to binding.

Second Messengers

Small molecules that relay and amplify signals from receptors to target molecules.

Calcium Ions

A common second messenger involved in various cellular functions.

Cyclic AMP (cAMP)

A second messenger involved in activating protein kinase A and regulating many cellular processes.

Inflammatory Response

The body's initial response to infection or injury, characterized by swelling, redness, warmth, and pain.

Adaptive Immunity

The immune response that targets specific pathogens using B and T lymphocytes.

Antigen

A foreign molecule that elicits a specific immune response.

Clonal Selection

The process by which a specific lymphocyte is activated and proliferates in response to an antigen.

Memory Cells

Long-lived immune cells that provide a rapid response upon re-exposure to a previously encountered antigen.

Cytotoxic T Cells

T cells that directly kill infected or cancerous cells.

B Lymphocytes

Immune cells that produce antibodies against specific antigens.

Antibodies

Proteins secreted by B cells that specifically bind to antigens to neutralize them.

Opsonization

The process by which antibodies coat pathogens, marking them for destruction by phagocytes.

Complement Fixation

A process where antibodies recruit proteins that help destroy pathogens.

Natural Killer Cells

A type of immune cell that directly attacks infected cells and tumors without prior sensitization.

Neurotransmitters

Chemical messengers that transmit signals across synapses from one neuron to another.

Acetylcholine

A neurotransmitter essential for muscle contraction and autonomic nervous system functions.

Dopamine

A neurotransmitter associated with pleasure, reward, and motor control.

GABA (Gamma-Aminobutyric Acid)

The primary inhibitory neurotransmitter in the brain, reducing neuronal excitability.

Neuropeptides

Short chains of amino acids that act as signaling molecules in the nervous system.

Electrical Synapses

Connections between neurons allowing rapid direct passage of ions and electrical signals.

Chemical Synapses

Neural connections involving neurotransmitter release and receptor binding for signal transmission.

Refractory Period

A period following an action potential during which a neuron cannot fire again.

Hypothalamus

A brain region that controls the pituitary gland and regulates various bodily functions.

Relay Proteins

Proteins involved in transduction that propagate signals inside the cell.

Endocrine System

A system of glands that secrete hormones to regulate bodily functions.

Pathogens

Microorganisms that can cause disease.

Plasmodesmata

Channel-like structures that enable communication between plant cells.

Gap Junctions

Connections between animal cells allowing the passage of ions and small molecules.

MHC (Major Histocompatibility Complex)

Glycoproteins on cell surfaces that help distinguish self from non-self in the immune response.

Extravasation

The process by which white blood cells exit the bloodstream to respond to infection.

Homeostasis

The regulation and maintenance of a stable internal environment in an organism.

Lymphatic System

A network that assists in maintaining fluid balance and is crucial for immune functioning.

Signal Amplification

The process by which a single signaling molecule can produce a large response in the target cell.

Receptor Tyrosine Kinase (RTK)

A type of enzyme-linked receptor that autophosphorylates upon ligand binding.

Endocrine Glands

Glands that secrete hormones directly into the bloodstream.

Homeostatic Mechanisms

Processes that maintain balance in physiological systems, such as temperature regulation.

Cytokines

Signaling proteins released by cells that affect the behavior of other cells in the immune system.

Antigen Presentation

The display of antigen on the surface of cells by MHC molecules for recognition by T cells.

Apoptosis

Programmed cell death that removes damaged or unnecessary cells.

Transcription Factors

Proteins that help regulate the transcription of genes in response to signaling pathways.

Neuroplasticity

The ability of the nervous system to reorganize itself by forming new neural connections.

Cell Surface Receptors

Proteins on the cell surface that bind to signaling molecules and trigger a response within the cell.

Phagocytosis

The process by which cells engulf and digest foreign particles or pathogens.

Cytokine Storm

An overproduction of cytokines leading to severe inflammation and tissue damage.

T Cell Receptor (TCR)

A molecule found on T cells that recognizes specific antigens presented by MHC.

B Cell Activation

The process that occurs when a B cell encounters an antigen, leading to its differentiation and antibody production.

Innate Immunity

The non-specific defense mechanisms that an organism is born with to protect against pathogens.

Adaptive Immunity

The immunity that develops over time in response to exposure to specific pathogens, involving B and T cells.

Antigenic Variation

The process by which pathogens change their surface proteins to evade the immune response.

Vaccine

A preparation that stimulates an immune response to confer immunity against a specific pathogen.

Immunological Memory

The ability of the immune system to remember and respond more effectively to previously encountered pathogens.

Hystamine

A compound released by cells during allergic reactions that causes inflammation.

Autoimmunity

A condition in which the immune system mistakenly attacks the body's own cells.

Immune Tolerance

The ability of the immune system to recognize self-antigens and avoid attacking the body's own cells.