What is Homeostasis?Homeostasis is the property of a system in which variables are regulated so that internal conditions remain stable and relatively constant.

What is Negative Feedback? Give an example?Negative Feedback is a feedback in which the system reduces the stimulus-induced output or activity to restore homeostatic levels of the variable.An example is temperature. If the temperature in a room is warm, the thermostat can set the AC on to cool the room. Once the desired temperature is reached, the AC is turned off.

What is Positive Feedback? Give an example?Positive Feedback is a feedback in which the system increases the stimulus-induced output or activity above homeostatic levels of the variable.An example occurs during childbirth. An increase in pressure in the cervical wall evokes the release of OXYTOCIN from the brain, which induces uterine contractions. The contractions further increase cervical pressure and even more OXYTOCIN is released.

What are the components of Homeostatic Control Mechanism?5 components:1. A receptor that receives stimulus or information2. The Afferent Pathway (going to something) that sends information to integrating center3. Integrating Center that process and compares it to homeostatic values4. Efferent Pathway (going away or exit) that sends information to effector5. Effector that elicits a response

What are the components of the Fluid Mosaic Model?There are 4 components: (a) the phospholipid bilayer; (b) the protein structures; (c) cholesterol; and (d) carbohydrates.

Describe the phospholipid bilayer?The phospholipid bilayer is a physical barrier separating internal and external cellular environment.It is made of phosphate heads which are negatively charged, polar, & hydrophilic molecules and lipids tails which are nonpolar, uncharged, and hydrophobic molecules.

Describe the proteins structures found in the bilayer? Where are the proteins situated? And what function do they serve?There are 2 types of proteins found in the bilayer: Integral Proteins, and Peripheral ProteinsIntegral Proteins are partially embedded in the bilayer and are amphipathic (polar and nonpolar at the same time). The portions in direct contact with the aqueous environment inside or outside the cell are polar. The part associated with the lipid bilayer is non-polar.Peripheral Proteins are attached to the membrane (bilayer) and are polar.Proteins may function as enzymes, channels, or receptors.

Where is cholesterol found in the bilayer? What is the function of cholesterol? What type of molecule is it (polar or non-polar)?Cholesterol is inserted in the phospholipid bilayer. They are amphipathic molecule.Cholesterol stabilizes the cell. (Without cholesterol the cell would be too fluid and permeable) Cholesterol is in yellowWhere can you find the carbohydrates? What are its functions? Carbohydrates are attached to the external surfaces of membrane proteins - glycoproteins. They can also attach to lipids, where they are called glycolipids.They function in cell recognition & cell-cell adhesion

What are the 2 major types of transport within the cell? Passive Transport (does not require energy) and Active Transport (which may or may not require energy)

What are the characteristic of passive transport? Passive transport:(1) does not require energy,(2) involves movement of solutes from high to low concentration (down concentration gradient)* Solutes will flow until equilibrium is reached or no net movement of solutes occur.

What are the 3 characteristics of active transport? Active transport: (1) May or may not require energy(2) Involves transport of solutes against its concentration gradient (3) Requires CARRIER PROTEINS

What are the 3 major kinds of passive transport? Passive transports (1) Simple Diffusion transport of solutes across phospholipid bilayer, cell membrane, pore (always open), or channels (regulated opening)

(!!! Solutes needs to be non-polar)

(2) Osmosis Water movement by simple diffusion.

Because water is polar, it needs a trans-membrane protein AQUAPORIN that moves water from high to low (down its concentration gradient).

(3) Facilitated Diffusion simple diffusion via a carrier protein and are selective of solute.

What is the difference between pores and channels? Pores are unregulated and channels are regulated

What transmembrane proteins are used for OSMOSIS? Why? Aquaporins, because water is polar and cannot traverse the cell membrane

What are the 4 kinds of passive transport ion channels for polar substances?(1) Ligand-gated Ion Channel chemical binding to extracellular receptor site causes conformational changes that open channels (specific solutes passes through)

(2) Voltage-gated Ion Channel change in membrane potential opens gate

(3) Mechanically-gated ion channel stimulated to open by pressure, vibration, and stretch

(4) Leakage Ion Channel always opened and do not require any stimuli

What are the 2 types of active transport? Name their properties.Primary Active Transport requires a CARRIER PROTEIN, ATPase or Ion Pump to drive solutes against their concentration gradient. (ex: Na+/K+ pump)Secondary Active Transport does not utilize ATP; instead driving force arises from coupling a solute moving down its concentration gradient with a solute moving against its concentration gradient

What are the 2 types of secondary active transport?Symport solutes are transported in the same directionAntiport solutes are transported in opposite direction

What are the 4 properties of carrier-mediated transport?Specific for what it carriesMay or may not use energy (ATP)May allow solutes to flow down or against their concentration gradientHas a transport maximum (labeled Vmax) a limit on # of things that can go in and out

What is an advantage of carrier-mediated transport over simple diffusion?* Carries solute much faster than simple diffusion

What is the Ficks Law of Diffusion?Ficks Law of Diffusion is the speed at which solutes may diffuse via simple diffusion

J = P x A x (CO - Ci)Where,

J is the rate of solute (flux). If positive solute enters the cell, if negative solute leaves the cellP is the permeability of cell in cm/secA is the surface area in cm2CO is the concentration outside of the cell in mol/cm3 Ci is the concentration inside of the cell in mol/cm3

What 3 factors influence the permeability in Ficks Law of Diffusion?

Thickness of membrane, Temperature of cell membraneComposition of cell membrane

What is Tonicity?

Tonicity is the measure of osmotic pressure gradient between 2 solutions by semipermeable membrane.

What is Isotonicity?

Two solutions A and B are isotonic when the concentration of solutes in A is the same as B, thus no water movement.

What is Hypertonicity?

Hypertonicity refers to a greater concentration.

A hypertonic solution is one with a higher concentration of solutes outside the cell than inside the cell.

Water will flow outside of the cell, shrinking the cell.

What is hypotonicity?

Hypotonic refers to a lesser concentration.

A hypotonic solution has a lower concentration of solutes outside the cell than inside the cell.

Water will rush into cell bursting it.

Define Osmotic Pressure.

Pressure necessary to stop the net movement if water across a membrane

Describe the movement of water in an osmotic pressure gradient?

Water moves from low osmotic pressure to high osmotic pressure.

Define Osmolarity.

Measure of solute particles in a solution (SI Unit: Osm/L)

What is the normal osmolarity of human blood?

290 Osm/L

How can we derive osmatic pressure from osmolarity?

Multiply osmolarity by 19 mmHg

Define hyperosmotic.

Osmolarity of solution outside is greater than solution inside the cell

Define hypo-osmotic.

Osmolarity of solution outside is smaller than solution inside the cell

Define hyperosmotic.

Osmolarity of solution outside is the same as the solution inside the cell

What is the difference between osmolarity and tonicity?

Osmolarity is a measure of the number of all permeable and impermeable particles of solutes of solution while tonicity observes particles that are impermeable in a solution

ANS: Since all molecules are impermeable, we will look at tonicity. A red blood cell is 290 mOsm/L

A. NaCl = 2 dissociable particle 145 x 2 = 290 mOsm/L - Isotonic. B. Glucose = 290 mOsm/L (does not dissociate) - Isotonic C. Is same as choice A D. 290 mmol/L of NaCl = 290 X 2 = 580 mOsm/L - cell is hypotonic to solution in beaker E. 97 mmol/L of CaCl2 = 97 x 3 = 291 - cell is hypotonic to solution in beaker

Ans: C Starch and glucose does not dissociate: 290 mOsm/L + 290 mOsm/L = 580 mOsm/L

Solution outside of cell is hypertonic; RBC will shrink due to water moving outside of the cell

Ans: E Albumin will move from compartment 2 to compartment 1; Water follows the movement of albumin.

1 mOsm/L of NaCl or 0.5 mmol/L of NaCl (1 mOsmL/ (2 molecules))

Cannot compare mmol/L to mmol/L becayuse it does not account for dissociable elements. We use mOsm/L.

Convert the answer choices to mOsm/L

a) 1 mOsm/Lb) 0.5 mOsm/Lc) 3 mOsm/Ld) 2 mOsm/Le) 2 mOsm/L

C,D, and E are hypertonic