exam deck Flashcards
What is autocrine signaling?
Signaling where a cell responds to signals it produces itself.
Describe paracrine signaling.
Signals act on nearby cells and are usually destroyed or taken up locally.
How does endocrine signaling work?
Hormones travel through the bloodstream to reach distant target cells.
What is neuronal signaling?
Fast, specific communication through neurotransmitters and neurohormones across synapses.
Name four main types of cell surface receptors.
Ionotropic receptors, G protein-coupled receptors (GPCRs), receptor-enzymes, and integrin receptors.
What is the primary role of intracellular receptors?
to regulate gene transcription directly in the nucleus.
Which signaling pathway involves GPCRs activating adenylyl cyclase?
The cAMP pathway, where adenylyl cyclase converts ATP to cAMP, activating protein kinase A.
Which second messengers are produced in the GPCR-phospholipase C pathway?
IP₃ and DAG, which release Ca²⁺ from internal stores and activate protein kinase C.
What type of molecule typically binds to intracellular receptors?
Lipid-soluble molecules, such as steroid hormones, that can cross the plasma membrane.
How does calcium function as a second messenger?
Calcium can activate proteins directly or bind to calmodulin, influencing processes like muscle contraction.
What are the three main types of membrane transport?
Simple diffusion, facilitated diffusion, and active transport.
Describe simple diffusion.
Movement of molecules from high to low concentration without energy usage (e.g., O₂ and CO₂).
How does facilitated diffusion work?
Molecules move down their concentration gradient with help from a protein channel or carrier, without using energy.
What is active transport?
Movement of molecules against their concentration gradient, using energy (e.g., Na⁺/K⁺ pump).
How does the Na⁺/K⁺ pump function?
It transports 3 Na⁺ out and 2 K⁺ into the cell, using ATP, maintaining the cell’s ionic balance.
What are ion channels, and what types are there?
Proteins that allow ions to pass through the membrane; they can be open (leak) channels or gated (voltage, ligand, or mechanically gated).
What is the role of symport carriers?
To transport two substrates in the same direction across the membrane, like the SGLT transporter for Na⁺ and glucose.
Define antiport carriers.
Carriers that transport substrates in opposite directions, like the Na⁺/K⁺ pump.
Why is the electrochemical gradient important?
it drives the movement of ions across membranes, balancing concentration and electrical gradients.
What is the resting membrane potential, and what influences it?
The negative charge inside a cell relative to the outside, mainly influenced by K⁺ permeability.
How does the Na⁺/K⁺ pump contribute to cellular homeostasis?
It regulates cell volume, pH, and osmolarity by controlling ion distribution.
What happens if the osmolarity inside a cell is too high?
Water influx can cause cell swelling or even lysis.
Describe the role of the Na⁺/K⁺ ATPase in preventing osmotic imbalance.
By maintaining a low intracellular Na⁺ concentration, it prevents excessive water influx and cell swelling.
How is intracellular pH regulated?
Through Na⁺/H⁺ exchange, Na⁺-HCO₃⁻ cotransport, and Cl⁻/HCO₃⁻ exchange.
What are the three main functions of calcium regulation in cells?
Intracellular signaling, muscle contraction, and neurotransmitter release.
