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I chose a video by discovery news that explains how through galvanotaxis we can heal our wounds faster. Galvanotaxis is the response of an organism to an electrical stimuli. This video explains how under our skin we have an electrical ionized field that runs parallel to the surface. When we get wounded the current changes direction and runs perpendicular instead of parallel to the skin. This change in the current stimulates white blood cells to head to the wound to heal it. If low-level electrical fields are introduced, it can help wounds heal and skin regenerate up to 50% faster. Which I think is a really interesting concept that is used by healthcare workers like physical therapists through their "TENS" machines.

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I have choosen a web article “Cellular respiration’ from the NCBI bookshelf because it explains how cells create energy from glucose and oxygen. Cellular respiration is the process that produces ATP, the main energy source our bodies need to function. The article clearly outlines the three stages: glycolysis, the Krebs cycle, and oxidative phosphorylation. I selected this resource because it is detailed, reliable and connects directly to major concepts we are covering for the exam. This concept matters because without cellular respiration, cells could not survive or carry out essential activities. A real-life example is how athletes breathe harder during exercise. Their muscle cells rapidly use glucose and oxygen to make ATP, which increases the demand for oxygen and energy. This process shows how cellular respiration is directly tied to everyday activities like running, exercising, or even climbing stairs.

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Introduction

Osmosis, Greek for push, is the net movement of water across a semipermeable membrane (see Figure. Osmosis).[1][2] Across this membrane, water tends to move from an area of high concentration to an area of low concentration. It is important to emphasize that ideal osmosis requires only the movement of pure water across the membrane without any movement of solute particles across the semipermeable membrane. Osmosis can still occur with some permeability of solute particles, but the osmotic effect becomes reduced with greater solute permeability across the semipermeable membrane. It is also true that, at a specific moment, water molecules can move towards either the higher or lower concentration solutions, but the net movement of water is towards the higher solute concentration. The compartment with the highest solute and lowest water concentration has the greatest osmotic pressure. Osmotic pressure can be calculated using the Van 't Hoff equation, which states that osmotic pressure depends on the number of solute particles, temperature, and how well a solute particle can move across a membrane. Its measured osmolality can describe the osmotic pressure of a solution. The osmolality of a solution describes how many particles are dissolved in the solution. The reflection coefficient of a semipermeable membrane describes how well solutes permeate the membrane. This coefficient ranges from 0 to 1. A reflection coefficient of 1 means a solute is impermeable. A reflection coefficient of 0 means a solute can be freely permeable, and the solute cannot generate osmotic pressure across the membrane.[2] The compartment with the greatest osmotic pressure pulls water in and tends to equalize the solute concentration difference between the compartments. The physical driving force of osmosis is the increase in entropy generated by the movement of free water molecules. It is also thought that the interaction of solute particles with membrane pores generates a negative pressure, which is the osmotic pressure driving the water flow.[3] Reverse osmosis occurs when water is forced to flow in the opposite direction. In reverse osmosis, water flows into the compartment with lower osmotic pressure and higher water concentration. This flow is only possible by applying an external force to the system. Reverse osmosis is commonly used to purify drinking water and requires energy input.[4] The concept of osmosis should not be confused with diffusion. Diffusion is the net movement of particles from an area of high to low concentration. One can think of osmosis as a specific type of diffusion. Both osmosis and diffusion are passive processes and involve the movement of particles from an area of high to low concentration.[2][5]

Cellular Level

The rate of osmosis always depends on the concentration of solute. The process is illustrated by comparing an environmental or external solution to the internal concentration found in the body. A hypertonic solution is any external solution with a high solute concentration and low water concentration compared to body fluids. In a hypertonic solution, the net movement of water is out of the body and into the solution. A cell placed into a hypertonic solution shrivels and dies by a process known as plasmolysis. An isotonic solution is any external solution with the same solute and water concentrations as body fluids. In an isotonic solution, no net movement of water takes place. A hypotonic tonic solution is any external solution with a low solute concentration and high water concentration compared to body fluids. In hypotonic solutions, there is a net water movement from the solution into the body. A cell placed into a hypotonic solution swells and expands until it eventually bursts through a process known as cytolysis. These three examples of different solute concentrations illustrate the spectrum of water movement based on solute concentration through osmosis. The body, therefore, must regulate solute concentrations to prevent cell damage and control the movement of water where needed.

Summary of Red Blood Cell Placed into Hypertonic, Isotonic, and Hypotonic Solutions

Hypertonic

A hypertonic solution has a higher solute concentration than the intracellular solute concentration. When a red blood cell is placed in any hypertonic solution, free water is moved out of the cell and into the solution. This movement occurs through osmosis because the cell has more free water than the solution. After the solutions are allowed to equilibrate, a cell with a lower overall volume results. The remaining volume inside the cell has a higher solute concentration, and the cell appears shriveled under the microscope. The solution is more dilute than originally. The overall process is known as plasmolysis.

Isotonic

An isotonic solution has the same solute concentration as the intracellular solute concentration. No net water movement occurs when a red blood cell is placed in an isotonic solution. The concentration of solute and water are equal both intracellularly and extracellularly; therefore, there is no net movement of water towards the solution or the cell. The cell and the environment around it are in equilibrium, and the cell should remain unchanged under the microscope.

Hypotonic

A hypotonic solution has a lower solute concentration than the intracellular solute concentration. When a red blood cell is placed in a hypotonic solution, free water moves into the cell. This situation results in an increased intracellular volume with a lower intracellular solute concentration. The solution ends up with a higher overall solute concentration. Under the microscope, the cell may appear engorged, and the cell membrane may eventually rupture. This overall process is known as cytolysis. Note that osmosis is a dynamic equilibrium, so, at any given moment, water molecular can momentarily flow toward any direction across the semipermeable membrane, but the overall net movement of all water molecules be from an area of high free water concentration to an area of low free water concentration.[5][6]

Clinical Significance

Water is known as the "universal solvent," and almost all life depends on it for survival. Therefore, though seemingly simple, the principle of osmosis plays a large role in almost all physiological processes. Osmosis is specifically important in maintaining homeostasis, which is the tendency of systems toward a relatively stable dynamic equilibrium. Biological membranes act as semipermeable barriers and allow for the process of osmosis to occur. Osmosis underlies almost all major processes in the body, including digestion, kidney function, nerve conduction, etc. It allows water and nutrient concentrations to be at equilibrium in all the body's cells. The underlying physical process regulates solute concentration in and out of cells and aids in excreting excess water out of the body.[2][7][8][9][10][11]

References

1.

Chen J, Sabir S, Al Khalili Y. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): May 1, 2023. Physiology, Osmoregulation and Excretion. [ PubMed: 31082152 ]

2.

3.

4.

5.

6.

Maldonado KA, Mohiuddin SS. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Aug 8, 2023. Biochemistry, Hypertonicity. [ PubMed: 31082139 ]

7.

8.

Meir E, Perry J, Stal D, Maruca S, Klopfer E. How effective are simulated molecular-level experiments for teaching diffusion and osmosis? Cell Biol Educ. 2005 Fall;4(3):235-48. [ PMC free article: PMC1200778 ] [ PubMed: 16220144 ]

9.

Schultz SG. Epithelial water absorption: osmosis or cotransport? Proc Natl Acad Sci U S A. 2001 Mar 27;98(7):3628-30. [ PMC free article: PMC33327 ] [ PubMed: 11274376 ]

10.

Ogobuiro I, Tuma F. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Jul 24, 2023. Physiology, Renal. [ PubMed: 30855923 ]

11.

Trigo D, Smith KJ. Axonal morphological changes following impulse activity in mouse peripheral nerve in vivo: the return pathway for sodium ions. J Physiol. 2015 Feb 15;593(4):987-1002. [ PMC free article: PMC4398533 ] [ PubMed: 25524071 ]

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Osmosis, Greek for push, is the net movement of water across a semipermeable membrane (see Figure. Osmosis).[1][2] Across this membrane, water tends to move from an area of high concentration to an area of low concentration. It is important to emphasize that ideal osmosis requires only the movement of pure water across the membrane without any movement of solute particles across the semipermeable membrane.

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Assignment 4: Asexual and sexual reproduction

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Assignment 4: Asexual and sexual reproduction

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I chose a video explaining the different types of reproduction because it shows how organisms are able to survive through reproduction. Asexual reproduction only requires one organism to reproduce and creates offspring that are genetically identical to the parent. Since one organism is required, reproduction is relatively fast and advantageous in populating more offspring, but it offers no genetic diversity to survive different environments. Sexual reproduction on the other hand, requires two parents to create an offspring and is more time consuming due to the process of fertilization and meiosis. Meiosis is the process that allows the chromosomes to create a unique combination of genetic expression for the offspring and leads to genetic diversity in the population. This is advantageous because diversity within the population means that organisms are able to adapt and evolve to changes in their environments. Understanding how Asexual and Sexual reproduction work is important in everyday life because it can help in understanding genetic research in diseases.

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I chose a web article that describes how convergent and divergent are evolutionary concepts that explain how species were able to adapt to their environments over time. Convergent evolution explains how unrelated species develop similar traits due to experiencing the same environmental pressures. An example of convergent evolution would be sharks and dolphins, both developed streamlined bodies suited for their ocean environment but are not closely related. Divergent evolution on the other hand, is the process of species evolving to have different characteristics to adapt in different niches of an environment. Darwin's study of finches demonstrates a clear representation of divergent evolution occurring, as they derived from one bird and developed different beaks and traits that helped them survive in different eco niches. By understanding these concepts people can differentiate between species that are related and exhibit similar features, and species that are unrelated but were under similar environmental pressure that evolved similar traits.

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Convergent and divergent evolution | Research Starters | EBSCO Research

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Convergent and divergent evolution are two key concepts in evolutionary biology that describe how species adapt to their environments over time. Divergent evolution occurs when closely related species evolve different traits as they adapt to varying ecological niches, often resulting in a wide variety of forms and behaviors. A classic example is Darwin's finches, which evolved from a single ancestor to exploit different food sources on the Galápagos Islands, leading to diverse beak shapes and sizes suited to their unique diets.

In contrast, convergent evolution refers to the process where unrelated species develop similar traits or adaptations due to facing similar environmental pressures. For instance, sharks, dolphins, and ichthyosaurs all evolved streamlined bodies and other adaptations for life in the ocean, despite their differing evolutionary backgrounds. Both processes illustrate the dynamic interplay between organisms and their environments, emphasizing that adaptation can arise through both shared ancestry and independent evolutionary pathways. Understanding these concepts provides insight into the complexity of life on Earth and the mechanisms driving biodiversity.

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Diagram showing chloroplast in plant leaf

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Padlet Assignment 3: Chloroplast Structure 

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Padlet Assignment 3: Chloroplast Structure 

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I chose this diagram because it showed the structure of a chloroplast in a plant leaf. Photosynthesis occurs in the chloroplasts, and the thylakoids inside the chloroplasts are flat circular structures. A group of thylakoids is called a granum. Tylakoids are embedded with chlorophyll, which is responsible for reflecting green wavelengths. Light-dependent reactions also occur in the thylakoids, where their main purpose is to convert light to chemical energy. The stroma is the fluid that surrounds the grana and is responsible for gas exchange and the Calvin cycle. This resource makes it easier to visualize the process of photosynthesis that occurs in nearly all plants. Being able to understand the process in which chloroplasts work is important because our everyday life depends on oxygen produced by phototrophs through photosynthesis.

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Diagram showing chloroplast in plant leaf illustration Stock Vector Image & Art - Alamy

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Download this stock vector: Diagram showing chloroplast in plant leaf illustration - J2HTK2 from Alamy’s library of millions of high resolution stock photos, illustrations and vectors.