Lecture 2-4

Question 1

Define kinetic energy

Answer 1

Energy a body possesses by being in motion

Question 2

Define thermal energy

Answer 2

Energy that comes. From heat. Faster particles move= the more heat generated

Question 3

How are thermal and kinetic energy related to molecular movement.

Answer 3

Diffusion means random molecular movement; therefore, the energy that causes diffusion is kinetic energy. Whenever something needs energy to go from low to high [ ], additional energy must be applied and can be in the form of thermal energy (active transport) p.46

Question 4

Define diffusion

Answer 4

Movement of particles from high to low [ ]

Question 5

Define osmosis

Answer 5

Movement of a solvent -water- from region of low [ ] to high [ ]across a semipermeable membrane.

Question 6

How does diffusion and osmosis r/t semipermeable membrane?

Answer 6

Cell membrane is semipermeable membrane and it is what maintains the [ ] of either side of it. Therefore for there to be a [ ] gradient for which the process of diffusion or osmosis is to occur would really depend on the semipermeable membrane

Question 7

How is osmotic pressure generated?

Answer 7

Water is continually trying to balance [ ] on either side of membrane. Ex; the L side compartment can never completely remove all water from r side. As pressure is building from the water moving from R to L side the water will begin to slow movement from R to L. Until max is reached then there will be some water pushed back to the R side d/t osmotic pressure

Question 8

Difference between diffusion and facilitated diffusion:

Answer 8

Diffusion is simple movement from high to low [ ] w/o energy or transporter.
Facilitated is movement from high to low [ ] as well w/o energy but it does require a transporter.

Question 9

Define active transport

Answer 9

A transporter w/ assistance of ATP input will be able to move particles against gradient (low to high [ ])

Question 10

Difference btw primary and secondary active transport

Answer 10

Primary uses ATP /GTP and readily Req’s ATPases
Secondary energy is derived secondarily from [ ] differences of molecular/ionic substances created originally by primary active transport

Question 11

Uniporters

Answer 11

Facilitated- down electrochemical gradient, uses stereospecificity, competitive, one substance at a time

Question 12

Multiporters

Answer 12

Includes symporters and antiporters. Moves 2 or more particle simultaneously in one or both directions through membrane.

Question 13

Uniporters /Multiporters r/t movement across membrane

Answer 13

Uniporters /Multiporters are transmembrane proteins that take part in electrochemical gradient by distributing these substances crating [ ]. Gradients on either side of membrane

Question 14

Brush border [fig 4-15]

Answer 14

Transport of sodium ions through epithelial sheet. The brush border on luminal side of cell is permeable to sodium and water diffusing readily from lumen to interior of cell. However, the basal surface of the cell Req’s active transport into ECF of surrounding connective tissues and blood vessels. Creates high [ ] of Sodium ions in membrane at the Basolateral sides of the epithelial cells result in transport not only of sodium but water too.

Question 15

How can body compartments be altered?

Answer 15

Diffusion: simple facilitated, and by active transport

Question 16

DEfine excitable cell

Answer 16

Cells in which an AP can be induced. Ex: neuron, skeletal, cardiac, smooth muscle

Question 17

What part of the neuron is capable of developing an AP?

Answer 17

DEndrites and axon conduct local potentials. Voltage-gated ion channels can generate an AP.

Question 18

Characterize cell membrane w/o ion channels

Answer 18

Biphospholipid layer is generally only permeble to lipid soluble (hydrophobic-nonpolar substances). Hydrophilic substances are prohibited from passing the membrane.

Question 19

Permeability of membranes to ions at rest:

Answer 19

Sodium and Ca++: low permeability at rest
Potassium: high at rest
Chloride: moderate at rest

Question 20

Major types of ion channels present on cell membranes:

Answer 20

Voltage, ligand, and Modality- gated channels

Question 21

Voltage-gated channels

Answer 21

Changes in voltage/charges

Question 22

Ligand-gated channels

Answer 22

Binding of specific molecules to receptor

Question 23

Modality-gated channels

Answer 23

Mechanical changes-differences in pressure

Question 24

Nernst potential

Answer 24

Ion difference on either side of membrane that exactly opposes the net diffusion of a particular ion through membrane
E = 2.3 RT/F log Co / Ci

Question 25

Assumptions of the Nernst equation:

Answer 25

1- can only be used for one ion at at time.

2- membrane must be completely permeable to the ion.

Question 26

Diffusion potential

Answer 26

Ion [ ] difference on either side of a membrane

Question 27

Equilibrium potential

Answer 27

Determined by [ ] and electrical forces. Where the electrical force driving Cl-ions L to R is = force pushing R to L

Question 28

Electrical neutrality principle

Answer 28

The sum of the [ ] of cations w/in any compartment must be = the sum of the [ ] of anions—sol’n is electrically neutral

Question 29

Donnan equilibrium

Answer 29

Specifies condition that must be met if 2 ions that can cross a membrane are simultaneously to be at equilibrium, electrical potential across the membrane must exactly balance the [ ].

Question 30

3 characters of an AP

Answer 30

“All-or-none”, self-propagating, and non-decremental

Question 31

All or none

Answer 31

It will either occur or not

Question 32

Self-propagating

Answer 32

Each region of depolarization serves to generate AP’s on either side

Question 33

Non-decremental

Answer 33

It does not decrease in strength

Question 34

Types of ions channels

Answer 34

Slow leak and gated channels

Question 35

When are Slow leak channels open?

Answer 35

Always open

Question 36

Gated channels

Answer 36

Only open when certain conditions are met

Question 37

2 types gated channels

Answer 37

Ligand: Req’s attachment of a chemical messenger
Voltage: Req’ a change in membrane potential

Question 38

Sodium channels

Answer 38

Consists of 4 domains in cylindrical configuration w/ 6 hydrophobic transmembrane segments. S4 segment w/ in each domain has high + charge. Inactivation gate is asso. W/ hydrophilic linkage btw domains 3 and 4.

There are 2 gates. When both open=rapid depolarization

Question 39

Potassium channels

Answer 39

Diameters are too small for hydrated K+ or Na+. There’s selectivity filter in channel by way of carbonyl groups. Slower kinetics than Na+ channels. This is primary mechanism for repolarization

Question 40

Voltages asso. W/ propagation of AP

Answer 40

Resting: -90 mV (Na activation closed-inactivation open)[K channel closed]
Depolarization: -90 - +35 (sodium gates are open. Approx. -60)
Repolarization: +35 - 90 (sodium inactivation gate closes but activation is still open—–K channels slowly open
Hyperpolarization:

Question 41

2 ways an axon can increase speed of conduction of AP

Answer 41

1-increasing diameter of axon:larger area for internal flow of current
2-increasing membrane resistance of the axon: insulation[myelin]-capacitor effect…essential b/c it is insulated there can be more charge d/t more area for the plate of the capacitor[ICF&ECF]

Question 42

Define absolute refractory period

Answer 42

Period that 2nd AP CANNOT be elicited no matter how strong the stimulus

Question 43

Define relative refractory period

Answer 43

A stronger than normal stimulus can cause an AP

Question 44

Effect of changes in sodium/potassium ion [ ] in ECF on membrane potentials

Answer 44

Shows how significant balance of Extracellular ions is. Ex in class: Ca++ depleted cattle slowly infuse Ca++to correct value or it would die.