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BIO304: Human Physiology

Unit 4: Movement of Materials and Cell Signaling   This unit will discuss the fluid compartments in the body and the movement of materials between them. The movement of particles from an area of higher concentration to an area of lower concentration is known as diffusion. Sodium, for example, is found in high concentrations outside the cell and lower concentrations inside the cell. If a special channel in the cell membrane opens, sodium can diffuse across the membrane from the area of higher concentration (outside) to the area of lower concentration (inside). The diffusion of water is called osmosis. It is important to have a good understanding of how diffusion and osmosis work, because cell physiology depends on these activities. We will also review the resting membrane potential of the cell as well as cell communication through various signaling pathways. You will see sodium again as an important player in these processes. These are difficult concepts, so review the material as many times as necessary in order to get a good grasp of the material.

Unit 4 Time Advisory
This unit should take approximately 5.25 hours to complete.

☐    Subunit 4.1: 3.25 hours

☐    Subunit 4.2: 1.25 hours

☐    Subunit 4.3: 0.75 hours

Unit4 Learning Outcomes
Upon successful completion of this unit, the student will be able to: - describe intracellular and extracellular compartments of the body; - describe active (i.e. primary and secondary) and passive (i.e. diffusion, facilitated diffusion, and osmosis) transport; - describe the resting membrane potential and the role of potassium and sodium equilibrium potentials; - describe cell signaling and distinguish between exocrine and paracrine cell signaling; and - describe the role of protein receptors, second messengers, and G-proteins in cell communication.

4.1 Body-Fluid Compartments and Movement of Materials   - Web Media: YouTube: Khan Academy’s “Diffusion and Osmosis” Link: YouTube: Khan Academy’s “Diffusion and Osmosis” (YouTube)

 Instructions: Watch the lecture for an introduction to diffusion
and osmosis. You may recall from your earlier courses that diffusion
is the movement of particles from an area of higher concentration to
an area of lower concentration. Osmosis is simply the diffusion of
water. This video does a great job covering these sometimes
difficult concepts.  

 Watching this video and pausing to take notes should take
approximately 45 minutes.  

 Terms of Use: This video is licensed under a [Creative Commons
Attribution-NonCommercial-NoDerives United States License 3.0](). It
is attributed to the Khan Academy. 
  • Reading: Wikibooks’ Structural Biochemistry: “Cell Signaling Pathways/Circulatory System” Link: Wikibooks’ Structural Biochemistry: “Cell Signaling Pathways/Circulatory System” (HTML)

    Instructions: Click on the link above, and read the section titled “Body Fluids” to learn about extracellular and intracellular environments. By understanding how the body is compartmentalized, we begin to see how homeostasis is maintained and a loss of homeostasis is controlled.

    Reading this section should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: Great Pacific Media’s “Diffusion Across Cell Membranes – Passive Transport” Link: YouTube: Great Pacific Media’s “Diffusion Across Cell Membranes – Passive Transport” (YouTube)

    Instructions: Watch this brief video for a quick summary of passive transport mechanisms. This video discusses two types of diffusion – simple and facilitated diffusion – as well as osmosis, the diffusion of water. The diffusion types discussed here are passive, meaning that energy is not required.

    Watching this video and pausing to take notes should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: Neurocirujo’s “Cell Membrane, Active Transport” Link: YouTube: Neurocirujo’s “Cell Membrane, Active Transport” (YouTube)

    Instructions: Watch this video on the action of the sodium-potassium pump, a common example of active transport through a cell membrane. As the video mentions, active transport requires ATP energy to run this pump. Without ATP, the pump will not run and sodium and potassium will not move across the membrane against their concentration gradient (from low concentration to high concentration).

    Watching this video and pausing to take notes should take approximately 5 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Assessment: McGraw-Hill Online Learning Center: Stuart Ira Fox’s “Interactions between Cells and Environment Quiz: Multiple Choice”, “Interactions between Cells and Environment Quiz: True or False”, and “Interactions between Cells and Environment Quiz: Critical Thinking Exercises” Link: McGraw-Hill Online Learning Center: Stuart Ira Fox’s “Interactions between Cells and Environment Quiz: Multiple Choice” (HTML), “Interactions between Cells and Environment Quiz: True or False” (HTML) and “Interactions between Cells and Environment Quiz: Critical Thinking Exercises” (HTML)

    Instructions: Click on the links above and complete these quizzes on basic cell membrane and transport concepts. These quizzes include a lot of questions that are helpful to test your understanding at this point. For the critical thinking questions, take a second after reading each question to think about how the concepts you have just learned apply, and formulate a short, thoughtful answer. Click the “Submit Answers” button at the bottom of the pages for instant feedback. Remember, you will not receive an official grade for these assessments; these quizzes are simply to help you review what you have learned.

    Completing these assessments should take approximately 2 hours.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

4.2 The Membrane Potential   - Web Media: YouTube: Great Pacific Media’s “Neuron Resting Potential” Link: YouTube: Great Pacific Media’s “Neuron Resting Potential” (YouTube)

 Instructions: Click on the link above, and watch this YouTube video
about the action of the resting membrane potential. Establishing a
negative interior charge (voltage) is important for neurons to be
ready to generate a signal (action potential). This concept is often
difficult at first. Watch this video as many times as needed to be
sure that you understand this process.  

 Watching this video and pausing to take notes should take
approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Web Media: YouTube: Khan Academy’s “Anatomy of a Neuron” Link: YouTube: Khan Academy’s “Anatomy of a Neuron” (YouTube)

    Instructions: Click on the link above and watch this brief lecture for an introduction to the nerve cell known as the neuron. Be sure that you have a grasp on the function of dendrites and the axon. This video provides basic information that must be understood in order to next learn about signaling between nerve cells and even signaling to other types of cells.

    Watching this video and pausing to take notes should take approximately 15 minutes.

    Terms of Use: This video is licensed under a Creative Commons Attribution-NonCommercial-NoDerives United States License 3.0. It is attributed to the Khan Academy. 

  • Reading: Wikibooks’ Animal Behavior/Neurophysiology: “Neurons”, “Neurophysiology”, and “Resting Potential” Link: Wikibooks’ Animal Behavior/Neurophysiology: “Neurons”, “Neurophysiology”, and “Resting Potential” (HTML)

    Instructions: Click on the links above, and read the sections “Neurons” and “Neurophysiology” through the subsection “Resting Potential” to learn about the membrane potential and the role of the K+ (potassium) and Na+ (sodium) equilibrium potentials. These concepts may seem difficult, because they are so abstract. However, it is necessary to have a good grasp of this material in order to conceptualize how neuron signaling to other neurons, muscles, and glands is carried out. When studying this, keep in mind that particles move from areas of higher concentration to areas of lower concentration (diffusion) and that at rest, sodium is higher outside the cell and potassium is higher inside the cell. Also, there are more negative proteins and chloride inside the cell than outside, making the inside negative relative to the outside. The cell must have this configuration at rest (resting membrane potential) in order for signaling to occur. This is called an electrochemical gradient. You may want to review the material several times.

    Reading these sections should take approximately 45 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

4.3 Cell Signaling   - Reading: Wikibooks’ Structural Biochemistry: “Cell Signaling Pathways” Link: Wikibooks’ Structural Biochemistry: “Cell Signaling Pathways” (HTML)

 Instructions: Click on the link above, and read the entire webpage
to learn how a cell receives a chemical signal and translates it
into an intracellular response. From this reading, you should gain
an appreciation for how complex this process can be and the number
of different players involved.  

 Reading this webpage should take approximately 30 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Web Media: YouTube: Rutvik Shah’s “Cell Communication” Link: YouTube: Rutvik Shah’s “Cell Communication” (YouTube)

    Instructions: Click on the link above and watch this video on the transduction of a chemical signal and its translation into an intracellular response through bondage to receptor proteins.

    Watching this video and pausing to take notes should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.