Chapter 3 - Cells and Tissues PowerPoint

Structural Units: Cells are the basic units of all living things, with the human body containing approximately 50 to 100 trillion cells.

Cell Theory:
- A cell is the basic structural and functional unit of living organisms.
- The activity of an organism depends on the collective activities of its cells.
- Biochemical activities of cells are determined by their structure (anatomy) which relates to function (physiology).
- Continuity of life is rooted in cellular processes.
Composition: Most cells consist of carbon, hydrogen, oxygen, and nitrogen, with about 60% water.

Function: Serves as a barrier, containing cell contents and separating them from the environment.
Fluid Mosaic Model:
- Comprised of two layers of phospholipids, cholesterol, and proteins.
- Sugar groups may be attached, forming glycolipids.
Proteins:
- Serve as enzymes, receptors, or transport channels/carriers.
Sugars:
- Glycoproteins and glycocalyx play roles in cell signaling and structure.
Cell Junctions:
- Types include tight junctions (prevent leakage), desmosomes (anchor cells), and gap junctions (communication).

Control Center:
- Contains DNA necessary for protein synthesis and cell reproduction.
Regions:
- Nuclear envelope (with pores), nucleolus (ribosome assembly), and chromatin (DNA and proteins).

Components:
- Cytosol: Fluid part.
- Inclusions: Chemical substances (e.g., stored nutrients).
- Organelles: Structures performing cell functions (e.g., mitochondria, ribosomes).
Mitochondria: Powerhouses of the cell, generate ATP.
Endoplasmic Reticulum: Rough (protein synthesis) and smooth (lipid metabolism) ER.
Golgi Apparatus: Modifies, packages, and secretes proteins.
Lysosomes and Peroxisomes: Contain digestive enzymes and detoxifying agents respectively.

Variety: The human body contains over 200 different cell types, varying in size, shape, and function.
Types of Cells:
- Connective Cells: Fibroblasts, erythrocytes.
- Muscle Cells: Skeletal, smooth, and cardiac.
- Nerve Cells: Neurons.
- Epithelial Cells: Cover and line body surfaces.

Cell Functions: Metabolize, digest, dispose of wastes, reproduce, grow, move, respond to stimuli.

Transport Mechanisms:
- Passive Processes: No energy required (e.g., diffusion, osmosis).
- Active Processes: Requires energy (e.g., active transport, vesicular transport).

Cell Cycle: Interphase (preparation, metabolic phase) and mitosis (cell division).
DNA Replication: DNA serves as the template for protein synthesis.
Translation and Transcription: Processes that convert DNA instructions into proteins.

Location: Covers body surfaces, forms linings and glandular tissue.
Function: Protection, absorption, filtration, secretion.
Types: Simple (one layer) vs. stratified (multiple layers) based on cell layers; squamous, cuboidal, and columnar based on cell shape.

Three Types:
- Skeletal: Voluntary, striated, multi-nucleated.
- Cardiac: Involuntary, striated, one nucleus, intercalated discs.
- Smooth: Involuntary, spindle-shaped, one nucleus.

Function: Conducts electrochemical impulses, composed of neurons and supporting neuroglia.

Healing Processes: Regeneration (same cell type) and fibrosis (scar tissue).
Factors Influencing Repair: Tissue type and injury severity.
Regenerative Capacity: Varies among tissues (e.g., epithelial tissues regenerate well, while cardiac muscle does not).

Cell proliferation continues into puberty, with certain tissues becoming amitotic.
Aging and neoplasms can affect tissue regeneration.