Cell Membrane Structure and Transport Mechanisms

Phospholipid Bilayer Structure

• Phospholipid bilayers form micelles in aqueous solutions.
• They contain a hydrophilic head and a hydrophobic tail.
• They form bilayers in cell membranes.

Transmembrane Proteins

• Carrier proteins, receptors for hormones or neurotransmitters and channel proteins are types of transmembrane proteins.

Activation Energy

• Determines the speed of a reaction.
• Acquired from kinetic energy of colliding molecules.

Cellular Ions

• If sodium ions are attracted to the inside of a cell, there's a net excess of negative charges inside the cell compared to outside.

Simple Diffusion

• Simple diffusion describes the movement of oxygen molecules across cell membranes.

Active Transport vs. Passive Transport

• Active transport requires energy; passive transport does not.
• Active transport involves adding energy for molecules to move across the membrane.
• Passive transport does not use extra-energy to help molecules move across membranes.

Transmembrane Protein Function

• A carrier protein is a transmembrane protein that uses conformational changes in its shape to move molecules across the membrane.

Homeostasis

• Homeostasis is the body's ability to maintain constant internal environment.
• Conformational changes in proteins are critical to this process.

Action Potential

• The action potential has phases: rapid depolarization, repolarization, and after-hyperpolarization.
• Graded potentials are limited in duration, not by the refractory period.

Postsynaptic Potentials

• Inhibitory postsynaptic potentials (IPSPs) move the membrane potential of the postsynaptic neuron away from threshold.

Membrane Potential

• If the sodium-potassium pump was turned off, the membrane potential would become zero mV (no difference in charge inside vs. outside the cell).

Electrical Gradients

• The electrical gradient for chloride ions (Cl-) moves chloride ions outwards.

Neurotransmitters

• Excitatory postsynaptic potential (EPSPs) and inhibitory postsynaptic potentials (IPSPs) can cause membrane potentials to change.

Blood Supply to the Brain

• The brain requires a constant supply of blood for energy production.

Blood-Brain Barrier

• Ions must be transported through endothelial cells in the blood-brain barrier to enter the brain's tissues.

Reflexes

• Muscle spindle stretch reflexes (knee-jerk reflex) are classified as spinal, somatic, innate, and monosynaptic.

Temperature Receptors

• Receptors for cold have a temperature range of 20-35°C and above 45°C.

Nervous System

• The spinal thalamic tract deals with sensory pathways.
• Sodium channels are largely closed during the absolute refractory period in the nervous system's response.

Cardiac Function

• Stroke volume is influenced by end-diastolic volume and ventricular contraction force.

Blood Vessel Contraction

• Several factors can influence the vasoconstriction or widening of blood vessels.

Blood Clotting

• Platelet plugs require von Willebrand factor and thromboxane for formation.

Respiration

• External respiration does not include the use of oxygen nor the generation of carbon dioxide.

This quiz covers essential concepts related to cell membrane structure and transport processes. Topics include the phospholipid bilayer, transmembrane proteins, activation energy, and the differences between active and passive transport. Test your knowledge on how substances move across cell membranes in biological systems.