Class 3

What are components of extracellular fluid?

- Interstitial fluid - Plasma

What are the 3 most prevalent ions in the ICF?

- K+ - HPO42- - Protein anions

LO: List the intracellular and extracellular concentrations of concentrations the following ions: K+, Na+, Cl-, Anions (A-), and Ca2+ ions (Table 7.2, p. 205). Draw a diagram of a cell showing these concentration gradients.

- K+ 30X more in cell - Na+ 10X out cell - Cl- 20X out cell - Anions 10X more in plasma than interstitial - Ca2+ 20,000X outside cell

What is the plasma membrane composed of?

- Lipid bilayer (phospholipids, fatty acids) - Proteins (ion, carrier, etc.)

LO: Describe the chemical characteristics and functions of the following components of the plasma membrane: lipid bilayer, proteins (include the following types of proteins: channels, carriers (also known as transporters), receptors, enzymes, and linkers shown in Fig 3.3).

- Lipid bilayer: provide a barrier and generate electrical/chemical gradients - Protein ion channels: movement of ions down concentration gradient, can be gated or not - Receptors: embedded in the plasma membrane of cells, act in cell signaling by receiving extracellular molecules. - Enzyme: increase rate of reaction, bind to ligand - Linkers: associated with movement and affect the shape of the cell.

What are the 3 most prevalent ions in the ECF?

- Na+ - Cl- - HCO3-

LO: Compare and contrast simple diffusion of a molecule across the lipid bilayer to the movement of an ion through an ion channel. Consider the 1) chemical characteristics of the molecules moving across the membrane, 2) whether or not a membrane protein is required, and 3) the driving force for the movement.

- Simple diffusion can take place in gases, and small, nonpolar, uncharged molecules so they move down their concentration gradient. Could use aquaporins or channels - Ions move through mediated channels and down their electrochemical gradient

What are characteristics of ion channels?

- transmembrane proteins - water-filled pores - specific regarding which ions can move through them - can be gated (open or closed) by various mechanisms

What is the concentration of Na+?

10x outside the cell

What is the concentration of Cl+?

20x outside the cell

What is the concentration of K+?

30x in the cell

What is an enzyme?

Catalyzes reaction inside or outside cell (depending on which direction the active site faces). - Integral or peripheral

Polar (e.g. H2O) or charged molecules (like ions) are moved across the membrane through...?

Channels or by carrier proteins

LO: Define a chemical gradient, an electrical gradient, and an electrochemical gradient across the plasma membrane of a typical cell.

Chemical: Unequal concentrations of substances inside or outside of the cell. Electrical: The difference in the electrical charges between the inner surface and outer surface of the membrane. Typically, the inner surface of the plasma membrane is more negatively charged and the outer surface is more positively charged. Electrochemical: concentration gradient + electrical gradient

What is an ion channel protein?

Forms a pore through which a specific ion can flow to get across membrane. Most plasma membranes include specific channels for several common ions. - Integral

What cannot pass through the membrane?

Ions, large polar uncharged molecules - Na+, glucose, proteins

Electrical signals in neurons are the result of ...?

Movement of ions across the plasma membrane through channels.

What is the lipid bilayer selectively permeable to? (readily diffuses)

Nonpolar, small, uncharged molecules - O2, steroids

Na and K concentration gradients are established and maintained by the _________

Primary Active Transport protein Na+-K+ ATPase

Which type of molecule is 10 times more prevalent in the plasma membrane in the plasma than in the interstitial fluid?

Protein anions

What is a receptor protein?

Recognizes specific ligand and alters cell's function in some way. - Integral

LO: Explain the concept of selective permeability of the plasma membrane, and describe the chemical characteristics of molecules that are most likely to diffuse across the lipid bilayer (Fig 5.1).

Selectively permeable to nonpolar, small, and uncharged molecules - large, charged/uncharged molecules cannot pass - small, polar, uncharged can slightly pass

What is interneuronal signaling?

Signaling between neurons that is transmitted by chemical signals

What is intraneuronal signaling?

Signaling within a neuron that is transmitted by electrical signals (AP) - Local current flow

What can only slightly pass through the membrane?

Small, uncharged polar molecules - H2O, urea

What is an electrical gradient?

The difference in the electrical charges between the inner surface and outer surface of the membrane. Typically, the inner surface of the plasma membrane is more negatively charged and the outer surface is more positively charged.

LO: Explain the mechanism by which primary active transport proteins can move molecules against their concentration or electrochemical gradient. Use the Na+/K+ ATPase (also called the Na+-K+ pump) as an example.

Through active transport - The Na/K ATPase works by pumping 3 Na out of the cell and 2 K into the cell

What is a carrier protein/transporters?

Transports a specific substance across membrane by undergoing a change in shape. - Integral

What is a chemical gradient?

Unequal concentrations of substances inside or outside of the cell.

What is an electrochemical gradient?

concentration gradient + electrical gradient

Since the lipid bilayers of cell membranes that separate the body fluid compartments are barriers to large and charged molecules, there can be __________ ___________ between adjacent compartments

concentration gradients

What is the relationship between the rate of diffusion and the concentration gradient of the solute?

direct

Uncharged molecules (like O2 and H2O) are not affected by the ___________ gradient across the plasma membrane (membrane potential)

electrical

Which proteins are expressed and where they are located on neurons dictate the _________ of that part of the neuron

function

K+ ions, which are positively charged, are attracted to the _________ of the cell

inside - K+ electrical gradient is inward

Both the chemical and electrical gradient determine the direction and rate of ion movement through ion channels because ________ ______ _________

ions are charged

The inside of the plasma membrane is slightly ___________ relative to the outside (negative membrane potential)

negative

How does the Na+/K+ pump work?

the hydrolysis of ATP by the pump provides the energy needed for the active transport of 3 NA+ ions out of the cell and 2 K+ ions into the cell, generating the gradients