Cell Communication Overview (Cell Signaling)

Give examples of hormones involved in long-distance signaling.

• Insulin, Human Growth Hormone (HGH), Thyroid Hormones (T3, T4), and Sex Hormones (Testosterone, Estrogen)

• Adrenaline, Cortisol, and Serotonin

• Insulin, Glucagon, and Melatonin

• Thyroid Hormones (T3, T4), Oxytocin, and Prolactin

What role do antigen-presenting cells (APCs) play in cell communication?

• APCs produce antibodies to fight infections.

• APCs act as scouts, capturing antigens and displaying them on their surface via MHC proteins.

• APCs directly kill infected cells to eliminate pathogens.

• APCs are responsible for the production of cytokines that regulate immune responses.

Why is cell communication important?

• It coordinates growth, differentiation, and homeostasis.

• It allows cells to reproduce rapidly without control.

• It prevents all forms of cellular damage.

• It eliminates the need for tissue and organ function.

What is the function of Killer T-cells (Cytotoxic T-cells)?

• They produce antibodies to neutralize pathogens.

• They make direct contact with infected or cancerous cells, deliver a death signal via perforins and granzymes, causing apoptosis in target cells.

• They enhance the activity of B-cells and other immune cells.

• They act as a memory for previously encountered pathogens.

What is apoptosis?

• A process of cell division

• Programmed cell death, often triggered by Killer T-cells in response to infected or cancerous cells.

• A type of cellular repair mechanism

• An inflammatory response to injury

What is the purpose of long-distance signaling?

• Local communication between cells

• System-wide coordination, such as growth, metabolism, and reproduction.

• Immediate response to stimuli

• Transmission of electrical signals only

What is the purpose of local signaling?

• To facilitate long-distance communication

• To ensure rapid local response and development

• To regulate global signaling pathways

• To enhance cellular metabolism

Give examples of local signaling mechanisms.

• Neurotransmitters, plant immune signaling, quorum sensing in bacteria, and morphogens.

• Hormones released into the bloodstream.

• Antibodies produced by B cells.

• Cytokines released by T cells.

Give an example of direct cell-to-cell contact.

• Immune cell interactions, such as antigen-presenting cells (APCs) interacting with Helper T-cells.

• Neurotransmitter release between neurons.

• Hormonal signaling between endocrine cells.

• Diffusion of nutrients through the bloodstream.

What is an analogy for chemical signaling?

• Like sending a text message — the signal travels, is received, and prompts a response.

• Like shouting across a room — the sound travels but may not be heard clearly.

• Like writing a letter — the message takes time to reach the recipient.

• Like a phone call — the message is immediate but can be interrupted.