qualitative thinking: For diffusion, we need to keep straight the difference between diffusion rate and iffusive flux. How do diffusive flux and diffusion rate differ? How do their units differ? Give an equation that relates the two. Based on Fick's equation for diffusive flux, what are some conditions that would increase flux and rate?

qualitative thinking: For diffusion, we need to keep straight the difference between diffusion rate and iffusive flux. How do diffusive flux and diffusion rate differ? How do their units differ? Give an equation that relates the two. Based on Fick's equation for diffusive flux, what are some conditions that would increase flux and rate?

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter7: The Peripheral Nervous System: Efferent Division

Section: Chapter Questions

Problem 1SQE

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1. Qualitative thinking: For diffusion, it is important to understand the differences between diffusion rate and diffusive flux. a. Define diffusive flux and diffusion rate and write their equations based on Fick's first law. b. Write an equation that relates the two and show how the units balance on each side. c. Fill in the what happens to diffusive flux and diffusion rate (increases, decreases or stays the same) when the variables in the left column changes as noted: Variable Concentration difference, AC Diffusion distance, Ax Diffusion area, A Diffusion coefficient, D Change Increases Increases Increases Increases Diffusive flux Diffusion rate
a. Define diffusion. Is diffusion a passive or an active process? Explain how solute moves in this way. b. Use your knowledge of diffusion to explain what happened over time when you observed a crystal of methylene blue dropped into a beaker of water. Be sure to use equilibrium in your explanation. c. Explain your observations over time after a drop of methylene blue and a drop of potassium permanganate were placed in the agar. What factors affect the rate of diffusion? d. What are tissues? Name the four major types of tissues in the human body. e. Name the three primary germ layers. Name the primary germ layers from which epithelial tissues and connective tissues develop. f. List general characteristics that all epithelial tissues have in common. g. Name the functions of epithelial tissue. Which type of epithelial tissue is found in areas that need protection? h. Know how to identify simple squamous epithelium, simple cuboidal epithelium, simple columnar…
Quantitative – diffusion time: Consider a spherical, single-celled organism which needs oxygen tosurvive. a. Assume oxygen needs to diffuse from the outside of the cell to its center. Write an equation thatgives the diffusion time in terms of the cell radius. b. The cell has a 4 micron (m) diameter, and diffusion coefficient of oxygen is 1.8 x 10-5 cm2/s inwater (assume diffusion is the same through the cell membrane). How long does it take for oxygento diffuse to the center of the cell? c. Cells typically need key molecules such as oxygen to survive. Diffusion times of oxygen can limithow big cells can become. If the cell gets too large for oxygen to reach its center, the cell coulddie. Calculate the size of a cell at which oxygen diffusion time becomes too slow and so limits theability of the cell to get that big. Explain your assumptions. How does this compare to typical cellsizes?
For this practice problem, would the answer be c)NaCl? My reasoning behind this is because molecules under 100 Da can use simple diffusion, while nonpolar molecules and larger molecules like benzene can use channels via facilitated diffusion. However, NaCl dissociates into ions and cannot readily use diffusion?
Calculate ΔGinward. Is energy required for transport to happen? The cell is at 25°C. Membrane potential = -60 mV. What is the ΔGinward for chloride? Use the chart.
Usually , rates of diffusion vary inversely with molecular weights; so smaller molecules diffuse faster than do larger ones. In cells, however, calcium ion diffuses more slowly than does cAMP. Propose a possible explanation.
To which in is the membrane most permeable? You should have learned several basic principles of electrophysiology. Describe the key principle that your answer is based on [Na+]=10mM [K+]=100mM [Na+]=100mM [K+]=10mM Vm= -60mV
The distribution of water is determined by solute concentrations. A hypertonic solution would cause a body cell to shrink in size. Both statements are true. Both statements are false. The first statement is true and the second statement is false. The first statement is false and the second statement is true. Spaced practice question: Consider a membrane protein and its chemistry. Which of the following would describe a channel protein? It is an inorganic compound. It is an example of a globular (functional) protein. It is stable when exposed to an acidic environment. It is an example of a fibrous (structural) protein.
A 500mL beaker is equally divided by a membrane permeable only to NaCl. Side A contains 250mL of a 1x10-6M of NaCl. Side B contains 250mL 1x10-12M of NaCl. In which direction will the NaCl diffuse? Select one: a. Diffuse Side A to Side B. b. Diffuse Side B to Side A. c. No diffusion will occur; it is already at equilibrium.
One of the important uses of the Nernst equation is in describing the flow of ions across plasma membranes. Ions move under the influence of two forces: the concentration gradient (given in electrical units by the Nernst equation) and the electrical gradient (given by the membrane voltage). This is summarized by Ohms law: Ix=Gx(VmEx) which describes the movement of ion x across the membrane. I is the current in amperes (A); G is the conductance, a measure of the permeability of x, in Siemens (S), which is I/V;Vm is the membrane voltage; and Ex is the equilibrium potential of ion x. Not only does this equation tell how large the current is, but it also tells what direction the current is flowing. By convention, a negative value of the current represents either a positive ion entering the cell or a negative ion leaving the cell. The opposite is true of a positive value of the current. a. Using the following information, calculate the magnitude of Na [ Na+ ]0=145mM,[ Na+ ]i=15mM,Gna+=1nS,Vm=70mV b. Is Na+ entering or leaving the cell? c. Is Na+ moving with or against the concentration gradient? Is it moving with or against the electrical gradient?
A. Assumed that the primary contributor to the absorbance of the samplewas due to the hemoglobins. Calculate how much red light the water in the sample absorbed.Explain whether or not ignoring water was a reasonable assumption. (use image down below to solve) B. There are several membrane-bound organelles in cells (e.g. nuclei, mitochondria,endoplasmic reticulum) that can also have ion channels in their membranes. Sketch anelectrical circuit model of a cell that expresses sodium, calcium, and chloride ion channels in itscellular membrane and calcium and chloride ion channels in its nuclear envelope membrane.
Below are three statements - two of which are truths and one is a lie. Which of the following statements is a lie? Select one: a.The primary active transport uses external chemical energy. b.The sodium-potassium pump which is an example of primary active transport is considered as the most important pump. c. In primary active transport, the energy is derived secondarily from energy that has been stored in the form of ionic concentration differences between the two sides of a membrane.