Chapter 3 Final Draft

[Audio] Hello, this is Chapter 3- Cells In this Video we will explore and dissect the human cell. Discuss it's functions (or it's physiology) and build a knowledge foundation that will allow us to learn about organs and organ systems in subsequent videos.

[Audio] The Human Cell The Cell is the structural or Anatomy and functional or Physiology unit of all forms of life or living matter..

[Audio] Cells vary in Size and Shape "As we explore the diversity of cells, it's important to understand that their form or shape is determined by what they do or their function in physiology. This principle is succinctly captured in the phrase 'Form Follows Function.' So, whether large or small, each cell's structure aligns with its specific purpose.".

[Audio] This is an excellent rendering of the Human cell. Take a moment to locate the following structures or organelles. Mitochondria, Nucleus, Rough and Smooth Endoplasmic Reticulum, Golgi Apparatus, and Lysosomes. When we speak of Extracellular, we are referring to Outside the cell. Intracellular is Inside the cell. When the membrane of the cell is crossed, substances are going from Extracellular to intracellular or from Intracellular to Extracellular..

[Audio] "Now, let's focus on the cell membrane – a crucial player in cellular function. Composed of a phospholipid bilayer with proteins, the cell membrane acts as a dynamic barrier, selectively allowing substances in and out. This balance is crucial for the cell's survival and function.".

[Audio] Cell Membrane Transport Across The Phospholipid Bilayer! "Cell membrane transport is a key concept in understanding how substances move across this semipermeable barrier. Pores and channels facilitate the movement of various substances. Importantly, this movement can occur with or without the expenditure of energy. It's a finely tuned process essential for the cell's homeostasis.".

[Audio] Nucleus Control center of the cell. "Now, let's delve into the intricacies within the cell. The nucleus stands as the control center, orchestrating cellular activities. It directs the show, playing a pivotal role in maintaining the cell's integrity and function.".

[Audio] Mitochondria, the "Power plants" of the cell. The Mitochondria is the Site of ATP or energy production. "Meet the powerhouse of the cell, the mitochondria. Often referred to as the 'power plants,' mitochondria are the sites where ATP, the energy currency of the cell, is produced. This energy is crucial for various cellular functions.".

[Audio] Ribosomes are the Site of protein synthesis. Synthesis means the production of chemical compounds by reaction from smaller or simpler materials such as elements, substances, or molecules..

[Audio] "Ribosomes, the protein synthesis sites, work hand in hand with the endoplasmic reticulum. This intricate system channels and moves substances, especially newly synthesized proteins. It's like a cellular conveyor belt ensuring the production of essential compounds." "Now, the Golgi apparatus steps in to 'package' proteins, ensuring they are ready for their designated roles..

[Audio] Lysosomes Break down intracellular waste and kills ingested bacteria using powerful enzymes. "Centrioles, key players in cell division, participate in the process that gives rise to two identical daughter cells..

[Audio] On the Cell Membrane Moving on to the cell membrane, microvilli increase surface area for better absorption, cilia move substances across the surface of membrane, and flagella enable cell movement, like a sperm swimming.".

[Audio] How do things go in and out of a cell Remember the Cell membrane is Permeably Selective! This determines what goes in and out of the cell, when it goes in or out , and what functions are completed. Let's explore how that is achieved..

[Audio] Passive transport mechanisms Passive transport mechanisms involve movement across the membrane without using cellular energy (ATP). 5 mechanisms provide passive transport; Diffusion, facilitated diffusion, osmosis, tonicity, and filtration. These processes play vital roles in maintaining the delicate balance within the cell.".

[Audio] Passive transport mechanisms Diffusion is the process of moving a substance from an area of high concentration to an area of low concentration..

[Audio] Facilitated diffusion Facilitated diffusion uses a Helper molecule in membrane assists movement of substances from an area of high concentration to an area of low concentration. In many cases the Helper molecule is a protein channel..

[Audio] Osmosis is the Diffusion of water or solvent from an area with more water to an area with less water; separated by a semipermeable membrane.

[Audio] With Filtration, water and dissolved substances cross the membrane in response to differences in pressures. In other words, pressure pushes substances through a permeable membrane..

[Audio] Passive transport mechanisms. Tonicity is the ability of a solution to affect movement across the cell membrane. Tonicity specifically relates to the composition of a fluid being moved. Hypertonic solutions cause cells to Shrink or Crenate. Isotonic solutions have no effect on cells. Blood is Isotonic. Normal Saline is Isotonic Hypotonic solutions cause cells to Swell and Burst or "lyse". As a nurse you will be administering these types of solutions when giving IV therapy..

[Audio] Active Transport Mechanisms "Active transport mechanisms, on the other hand, require cellular energy (ATP). The active transport pump moves substances uphill, against a gradient, demanding energy input. This is a crucial process in maintaining specific concentrations within the cell.".

[Audio] The Active Transport Pump is used to move substances uphill – from an area of low concentration to an area of high concentration. This is working against a "gradient" For example, it is harder to walk up a hill because the hill is "graded up". Against a gradient requires energy. Here is where our cellular energy, ATP is used. The use of energy requires the production of energy. Remember it is from the food we eat, water we drink, and digestion where we absorb glucose which is used to release high energy phosphate bonds to form ATP..

[Audio] "Endocytosis involves the ingestion of substances by the cell membrane. Phagocytosis engulfs solid particles, while pinocytosis, also known as 'cell drinking,' involves liquid droplets..

[Audio] Exocytosis is the secretion of cellular products out of the cell and requires energy. Secretion is a process by which substances are produced and discharged from a cell, gland, or organ.

[Audio] Cell Division Cycles Cells are constantly dividing and reproducing, on an average every 24 hours. This process occurs in cycles. Two main Cycles are Interphase and Mitosis. Interphase involves 3 steps; G1 or Gap phase, S phase or the phase of DNA synthesis, and the G2 phase of growth and preparation. Actual cell division occurs in Mitosis and has 4 phases. After Mitosis cells that are not going to continue to divide enter G0 phase or resting phase..

[Audio] During Mitosis or M Phase, the splitting of one mother cell into two identical daughter cells occurs in 4 distinct phases. Prophase, Metaphase, Anaphase, and Telophase culminating in the 2 identical daughter cells. The splitting of one mother cell into two identical daughter cells, ensures cellular replication..

[Audio] Sex Cell Reproduction Meiosis Occurs only in sex cells. Meiosis, exclusive to sex cells, results in the production of four daughter cells, each unique..

[Audio] Cell Differentiation "Cells begin as stem cells. They are undifferentiated. The diagram on the slide shows how one unspecialized stem cell can "differentiate" to become many specific cells. Differentiate means to Specialize.

[Audio] Understanding terminology like 'malignant,' 'apoptosis,' and 'necrosis' is crucial. Malignant cells are cancerous cells and extend into surrounding tissues. Benign cells are cancer cells that are not harmful. Apoptosis is a natural cell death process, used to rid the body of old or not healthy cells. Necrosis refers to the death of cells." When we say a tissue or cell is Necrotic, we mean it is dead..

References. Barbara Herlihy, B. M. (2022). The Human Body in Health and Illness. St. Louis: Elsevier, Inc. .. Sample