Cell Biology and Epithelial Tissue Quiz

Understanding the Organization of the Human Body

• This presentation covers the anatomy and physiology of the human body, focusing on cells, tissues, and organ systems.

• Learning objectives include describing organelles and their functions, explaining genetic code, and detailing plasma membrane functions.

• The cell life cycle, including mitosis, interphase, and cytokinesis, is discussed.

• Four major tissue types (epithelial, connective, muscle, and neural) and their organization in organs and systems are also addressed.

• The concept of homeostasis, negative feedback, and positive feedback are explained.

Outline

• Introduction to human cells
• Structure of a typical mammalian cell (subcellular organelles)
• Plasma membrane structure and functions
• Cell life cycle detailing mitosis and meiosis
• Body tissues (Epithelial, Connective, Muscular, Neural)
• Homeostasis

An Introduction to Human Cells

• Sex cells (Germ cells): Reproductive cells (ova/sperm; meiosis)
• Somatic cells: All body cells other than sex cells (mitosis)

Anatomy of a Model Cell (Parts 1 & 2)

• Cytoskeleton: Protein filaments for structural support and movement
• Plasma membrane: Lipid bilayer with embedded proteins for isolation, transport, and sensitivity
• Specific organelles like the nucleus, endoplasmic reticulum (ER), ribosomes, Golgi apparatus and mitochondria are discussed, including function and structure

Plasma Membrane

• Extracellular fluid (interstitial fluid): Watery medium surrounding the cell
• Plasma membrane (cell membrane): Separates the cytoplasm from the extracellular fluid.
• Cytosol: Liquid component of cytoplasm
• Organelles: Intracellular structures inside the cell.

Functions of the Plasma Membrane

• Acts as a barrier separating inside and outside of the cell.
• Controls the flow of substances into and out of the cell
• Helps identify the cell to other cells—e.g., immune cells
• Participates in intercellular signaling

Anatomy of a Model Cell (Part 3 & 4)

• Microvilli: Extensions of the plasma membrane increasing surface area for absorption
• Cilia: Long extensions of the plasma membrane, often involved in moving materials over cell surfaces.
• Ribosomes: Involved in protein synthesis, located on the rough endoplasmic reticulum or free in the cytoplasm
• Rough/Smooth ER/Golgi apparatus: involved in modifying and packaging proteins and synthesis of carbohydrates

Anatomy of a Model Cell (Part 5)

• Nucleus: Contains DNA, the control center of the cell
• Golgi apparatus: Modifies, sorts, and packages proteins for secretion
• Mitochondria: Powerhouse of the cell, responsible for cellular respiration and generating ATP
• Endoplasmic Reticulum (ER): Involved in protein and lipid synthesis

Organelles and the Cytoplasm

• Cytoplasm: Materials inside the cell (outside the nucleus)
• Cytosol: Fluid component of cytoplasm
• Materials dissolved in the cytosol include nutrients, ions, proteins, and waste products
• Other cellular structures that form organelles play specific roles.

Cell Nucleus

• Largest organelle, control center
• Contains DNA enclosed by a double membrane (nuclear envelope).
• Pores (nuclear pores) in the nuclear envelope allow communication between the nucleus and cytoplasm
• DNA organized into chromatin (heterochromatin and euchromatin).

Cell Nucleus (continued)

• Contents: DNA, nucleoplasm (fluid containing ions, enzymes, nucleotides, and RNA), nuclear matrix (support filaments).
• DNA contains instructions for all body proteins.

Protein Synthesis

• Gene activation: Activates DNA to create instructions needed to make proteins.
• RNA polymerase creates a messenger RNA (mRNA) copy of a gene
• Translation is the process of a transfer RNA (tRNA) anticodon attaching to the mRNA codon to assemble the amino acids.
• RER and Golgi apparatus are involved in post-translational modification and packaging.

Cell Life Cycle (continued)

• Three stages of mitosis: DNA replication, divisions of genetic material (mitosis), cytokinesis (division of cytoplasm)
• Purpose of cell division is to growth, repair and asexual reproduction

Mitosis

• Cell division results in two diploid cells from one diploid parent cell (each cell has a complete copy of the original DNA)
• Includes phases of Prophase, Metaphase, Anaphase and Telophase

Meiosis

• Two cell-division steps
• Produce gametes (ova and sperm)
• Only occurs in gonads (ovaries and testes)
• Creates four haploid cells from one diploid cell with half as many chromosomes

An Introduction to Tissues

• Tissues are structures with discrete structural and functional properties.
• Tissues combine to form organs (e.g., heart, liver)
• Organs are organized into organ systems (e.g., integumentary, nervous, endocrine, skeletal, muscular, circulatory, immune, respiratory, urinary, digestive, reproductive).

Four Types of Tissue

• Epithelial tissue coverings and linings
• Connective tissue- support and connect
• Muscle tissue- movement
• Nervous tissue- conducts impulses

Epithelial Tissue

• Forms coverings (i.e., skin) and linings (i.e., inner linings of organs and blood vessels)
• Has specialized cells (e.g. glands) that produce secretions
• Characteristics: polarity (apical and basal surfaces), attachment (basement membrane), avascularity, and regeneration

Connective Tissue

• Tissues include gel/fibers/cells to provide support and connection.
• Includes loose tissue, dense tissue, and specialized tissues like cartilage and bone.
• Specialized cells (e.g., RBCs, WBCs) and ECM (extracellular matrix)

Fluid Connective Tissues

• Includes blood and lymph
• Contains a watery matrix of proteins and various cells (e.g., RBCs, WBCs, platelets)

Supporting Connective Tissues

• Cartilage- shock absorbers
• Bone- calcified and providing weight support.

Muscle Tissue

• Specialized for contraction, producing movement.
• Includes skeletal, cardiac, and smooth muscle.

Neural Tissue

• Specialized for conducting electrical impulses and processing information.
• Includes neurons (nerve cells) and neuroglia (supporting cells).

Organs and Systems

• Groups of organs that work together to perform related functions.
• Examples include the integumentary system, the circulatory system, the nervous system etc

Homeostasis

• The body's ability to maintain a stable internal environment, despite fluctuations in the external environment.
• Systems respond to maintain homeostasis via feedback loops (positive and negative).

Negative and Positive Feedback

• Negative feedback: Maintains homeostasis. The response negates the stimulus, leading the body back to the normal range.
• Positive feedback: Amplifies the stimulus. The response enhances the changes away from the normal range. Examples include child birth and blood clotting