Human Anatomy and Physiology: The Cell Membrane

Flashcards covering the structure, composition, function, membrane transport, and cell communication aspects of the cell membrane.

What are the three main functions of the plasma membrane?

Physical barrier, gateway for exchange, and communication.

What are the main components of the cell membrane structure, and how are they arranged?

Phospholipids (forming a bilayer), cholesterol, proteins (integral and peripheral), glycoproteins, and glycolipids.

What property of phospholipids creates a barrier for the flow of molecules across the cell membrane?

The non-polar fatty acid tails.

What is the glycocalyx and what are its functions?

Glycoproteins and glycolipids on the cell surface involved in cell identity and cell orientation.

What are the two types of membrane proteins?

Integral (transmembrane) proteins and peripheral proteins.

What are the main functions of membrane proteins?

Ion channels, carriers, receptor sites, enzymes, pores, structural support, cell adhesion, and cell junctions.

What types of molecules can permeate the plasma membrane?

Small, uncharged, nonpolar (lipid-soluble) molecules.

What is the difference between passive and active membrane transport processes?

Passive processes do not require energy, while active processes require ATP.

What is a concentration gradient, and how does it influence membrane transport?

Difference in substance concentration across a membrane; substances tend to move down their concentration gradient.

What is simple diffusion?

Net diffusion from high to low concentration due to random particle collisions.

Name three factors that influence the rate of diffusion.

Temperature, concentration gradient, and diffusion distance.

What is osmosis?

Net diffusion of water down its own concentration gradient, pulled by non-diffusible particles.

What is tonicity and how does it affect osmosis?

The number of non-diffusible particles; it determines the direction of water movement.

Define isotonic, hypotonic, and hypertonic solutions.

Isotonic: same concentration of non-diffusible particles. Hypotonic: fewer non-diffusible particles. Hypertonic: more non-diffusible particles.

What is facilitated diffusion?

Passive transport aided by membrane proteins (channels or carriers).

What is the difference between channel-mediated and carrier-mediated facilitated diffusion?

Channel-mediated uses a protein as a channel only, while carrier-mediated requires action by the carrier protein.

What is the primary difference between facilitated diffusion and active transport?

Active transport moves substances against their concentration gradient and requires energy, while facilitated diffusion moves substances down their concentration gradient and does not require energy.

What is primary active transport?

Uses ATP directly to run a pump, such as the Na+/K+ ATPase pump.

What is secondary active transport (co-transport)?

Powered by the concentration gradient of one solute to move another solute against its gradient.

What is vesicular transport?

Transport using vesicles (endocytosis and exocytosis).

What are the different types of endocytosis?

Ligand-mediated endocytosis, phagocytosis, and pinocytosis.

What is cell communication and why is it important?

Important for controlling growth, reproduction, and other cellular processes; most use ligands (molecules that bind to cell or macromolecules).

Name the three types of receptors that bind ligands.

Channel-linked receptors, enzymatic receptors, and G protein-coupled receptors.

How do channel-linked receptors work?

Allow ions to move into or out of cells in response to neurotransmitter binding, initiating electrical changes.

How do enzymatic receptors work?

Are protein kinase enzymes that phosphorylate other enzymes, turning on their function.

How do G protein-coupled receptors work?

Indirectly activate protein kinase enzymes via a G protein and secondary messengers.

What is the role of secondary messengers in cell communication?

To amplify the initial signal and trigger a specific response inside the cell.

Describe the CAMP response.

Activates protein kinase, leading to a cascade of phosphorylation events and a cellular response.

Describe the role of Calcium as a second messenger

Activated IP3 causes release of Ca2+ from ER and DAG and IP3 activate enzymes

What is the function of Calmodulin?

Protein 2nd messenger similar to CAMP response. Activates protein kinase