Chapter 3 endoplasmic reticulum

Chapter 1: Introduction

  • Course: Science 223, Anatomy and Physiology 1 with Dr. Ray Thompson.

  • Focus: Endoplasmic reticulum (ER), two organelles:

    • Smooth Endoplasmic Reticulum (SER): smooth appearance.

    • Rough Endoplasmic Reticulum (RER): rough appearance due to ribosomes.

  • Importance of distinguishing between the two for understanding functions.

Chapter 2: Rough Endoplasmic Reticulum

  • Rough Endoplasmic Reticulum (RER): key organelle for protein synthesis.

    • Well developed in cells that secrete large amounts of protein.

    • Outer appearance rough due to the presence of bound ribosomes.

      • Free ribosomes: synthesis of soluble proteins

      • Bound ribosomes: synthesis of membrane & secreted proteins

      • Involved in the modification and folding of newly synthesized proteins before they are transported to their final destinations.

  • Ribosomes: multi-component particles made primarily of RNA, critical for translation (protein synthesis).

    • Translation: process where ribosomes convert mRNA into proteins.

    • Upon completing protein synthesis, ribosomes transition to free ribosomes in the cytosol.

  • Function of RER:

    • Protein insertion and modification within the ER.

    • Synthesis of phospholipids for membrane formation, particularly near SER border.

Chapter 3: Synthesis Of Cholesterol

  • Smooth Endoplasmic Reticulum (SER): involved in lipid synthesis and metabolism.

    • Performs synthesis and packaging of triglycerides (related to phospholipids).

  • Cholesterol: synthesized primarily in the liver from fatty acids; vital for hormone production.

    • Statins: drugs that inhibit cholesterol synthesis in the liver.

    • Cholesterol is converted to hormones in reproductive organs and adrenal glands.

Chapter 4: Smooth Endoplasmic Reticulum

  • Smooth Endoplasmic Reticulum (SER):

    • Involved in a variety of functions:

      • Lipid synthesis (triglycerides and cholesterol).

      • Drug and alcohol detoxification.

    • Breakdown of drugs and hormones in liver cells managed by SER.

  • Urine tests measure metabolites of substances processed in the liver and filtered by kidneys.

Chapter 5: Skeletal Muscle Cells

  • Storage Functions:

    • Glycogen: stored in liver and skeletal muscle cells; critical for blood glucose regulation.

      • Liver: can release glucose into the bloodstream; skeletal muscle cannot.

    • Calcium Storage:

      • Key in muscle function; stored in sarcoplasmic reticulum of skeletal muscle.

      • Three muscle types: skeletal, cardiac, and smooth.

      • Skeletal muscle has a well-developed sarcoplasmic reticulum for calcium storage.

Chapter 6: Conclusion

  • Endoplasmic Reticulum (ER) Overview:

    • Divided into two regions:

      • Smooth ER: synthesizes lipids, metabolizes drugs, stores cholesterol and calcium.

      • Rough ER: associated with protein synthesis and phospholipid formation for plasma membranes.

  • Understanding the roles of SER and RER is crucial for comprehending cellular functions and their significance in physiology.