Description: The lysosome is a yellow vesicle on the model, often likened to a police officer within the cell.
Function: It's crucial for cellular defense, containing digestive enzymes to break down harmful components.
Definition: A vesicle is a small, rounded capsule that transports substances throughout the cell, functioning similarly to an Uber.
Lysosomal Function: The lysosome is filled with powerful acidic digestive enzymes that roam the cell to neutralize pathogens and debris.
Acidic Nature: Lysosomes contain highly acidic enzymes that are effective in digesting particles.
Role in Pathogen Neutralization: These enzymes target and destroy any unwanted bacteria, viruses, or pathogens that penetrate the semi-permeable cell membrane.
Neutrophils: Neutrophils are white blood cells that attack pathogens but do not have digestive enzymes like lysosomes.
Purpose of Neutrophils: They increase in number in response to infections, providing a different layer of immune defense than lysosomes.
Description: Mitochondria are orange structures throughout the cell, known for their critical role in energy production.
ATP Production: Mitochondria are responsible for creating ATP (Adenosine Triphosphate), the only usable form of energy for cellular activities.
Powerhouse Concept: While commonly referred to as the powerhouse of the cell, the emphasis should be on their primary function of producing ATP.
Appearance: Spindle-shaped structures found within the cell, associated with the process of cell division.
Role in Mitosis: Centrioles are integral during mitosis, where cellular replication occurs. They assist in organizing microtubules that separate chromosomes.
Distinction Between Mitosis and Meiosis: Mitosis pertains to general cell division, while meiosis concerns the production of gametes (sperm and egg cells).
Non-dividing Cell: Red blood cells do not replicate like other cells due to the absence of a nucleus, which is extruded during maturation.
Shape and Function: The biconcave shape allows for increased oxygen transport capacity, as red blood cells carry oxygen using hemoglobin.
Four Main Types:
Epithelial tissue
Connective tissue
Muscle tissue
Nervous tissue
Focus for this session: A detailed look at epithelial and connective tissues will be discussed in the class.
Description: Tissues composed of tightly packed cells that line cavities and surfaces, providing protection, absorption, secretion, and filtration.
Types of Epithelial Cells: Categorized by shape (squamous, cuboidal, columnar) and layers (simple vs. stratified).
Simple Squamous: One layer thick, found lining blood vessels for efficient gas exchange.
Stratified Squamous: Multiple layers thick, found in areas like the reproductive organs and skin, providing protection against mechanical stress.
Keratinized Stratified Squamous: Notable for being part of the skin’s outer layer, acting as a barrier against environmental damage.
Types: Simple cuboidal (found in kidney and liver) vs. stratified cuboidal (found in sweat glands).
Features: Characterized by their tall, column-like shape.
Special Structures: Cilia (for movement) and goblet cells (mucus secretion) are distinctive to this type.
Locations: Found in the intestines, where they aid in nutrient absorption and transport.
Unique Ability: Transitional epithelium can stretch significantly, allowing the bladder to expand when filled with urine.
Location: Found lining the bladder, facilitating storage of urine without damage.
Misleading Structure: Appears layered but is a single layer of cells with staggered nuclei, termed pseudostratified.
Role: This epithelium lines passages such as the trachea, providing a mechanism for moving mucus and particles out of the airway using cilia.
Function: Supports and organizes other tissues and organs, providing strength and elasticity.
Classification: Divided into loose connective tissue and dense connective tissue, each with various subtypes.
Areolar Tissue: Most abundant, providing flexibility and support between layers of skin and muscle.
Adipose Tissue: Fat tissue that provides insulation, energy storage, and cushioning around organs.
Importance of Fat: Helps in insulation, protection, and energy storage—fat should not be completely eliminated from diets.
Reticular Tissue: Forms supportive frameworks for organs in the lymphatic system.
Regular Dense Connective Tissue: Comprised mainly of collagen fibers, strong and resilient, forming tendons and ligaments.
Differences between Tendons and Ligaments: Tendons connect muscles to bones, whereas ligaments connect bone to bone.
Irregular Dense Connective Tissue: Found primarily in the dermis of the skin, providing structural support.
Elastic Connective Tissue: Provides stretchability and resilience; found in blood vessels and fetal tissues.