Patho study Guide Week 1

Cellular Biology Overview

• Understanding cellular biology is necessary for grasping how various diseases function.

• Cells interact as multicellular social organisms through communication channels, or "cellular crosstalk."

Cell Types

• Two primary classes of cells exist:

  • Eukaryotes:

    • Cells from higher organisms (e.g., plants, animals) and single-celled organisms (e.g., fungi, protozoa).

    • Features membrane-bound organelles, including a well-defined nucleus.

    • Larger and more complex than prokaryotes.

    • Genetic information is contained within multiple chromosomes with histones.

  • Prokaryotes:

    • Include bacteria, rickettsiae, and cyanobacteria (blue-green algae).

    • Lack membrane-bound organelles and a defined nucleus; nuclear material is a single circular chromosome.

Cellular Functions

• Cells undergo specialization through differentiation processes. Eight chief cellular functions include:

  • Movement: Muscles cell contraction facilitates motion (e.g., blood vessel diameter change).

  • Conductivity: Electrical potential passing along nerve cells in response to stimuli.

  • Metabolic Absorption: Cells from intestines and kidneys absorb nutrients and fluids.

  • Secretion: Certain cells synthesize substances and release them (e.g., hormones).

  • Excretion: Removal of waste products through lysosomes.

  • Respiration: Cells convert nutrients into energy (ATP), primarily in mitochondria.

  • Reproduction: Essential for tissue growth and maintenance through cell division.

  • Communication: Vital for cell survival and coordination; includes insulin signaling.

Cellular Components and Structure

• Typical Eukaryotic Cell Components:

  • Plasma Membrane: Outer membrane controlling substance movement.

  • Cytoplasm: Fluid filling the cell matrix.

  • Organelles: Specialized structures performing distinct functions (e.g., mitochondria, Golgi apparatus).

• Nucleus: Largest organelle, contains most cellular DNA, involved in cell division and genetic information handling.

• Cytoplasmic Organelles:

  • Ribosomes: protein synthesis sites.

  • Endoplasmic Reticulum (ER): synthesizes proteins and lipids, involved in folding and sensing stress.

    • Rough ER (rER): studded with ribosomes, active in protein synthesis.

    • Smooth ER (sER): synthesizes lipids and detoxifies.

  • Golgi Apparatus: modifies and packages proteins for secretion.

  • Lysosomes: digestive organelles containing enzymes for breaking down waste.

  • Mitochondria: energy production via cellular respiration and ATP generation.

  • Peroxisomes: oxidative enzymes detoxifying fatty acids and other compounds.

  • Cytoskeleton: structural framework providing shape and facilitating movement through protein filaments (microtubules, actin filaments).

Membrane Transport

• Transport Mechanisms:

  • Passive Transport: Movement without energy use (e.g., diffusion, osmosis).

  • Active Transport: Requires energy to move substances against gradients via pumps.

  • Endocytosis: Engulfing substances into cells via membrane folding; includes clathrin-mediated endocytosis and phagocytosis.

  • Exocytosis: Releasing substances from cells, useful for secretion tasks.

Electrical Impulses and Membrane Potential

• Cell membranes maintain a resting membrane potential, where the inside of the cell is more negatively charged than outside.

• Action potentials are rapid depolarizations that propagate signals within neurons and muscles.

Cell Cycle and Reproduction

• The cell cycle is crucial for reproducing all living cells: divided into interfases and stages of mitosis.

  • Phases: G1 (growth), S (DNA synthesis), G2 (prep for division), M (mitosis).

• DNA damage affects cell cycle progression through signaling pathways leading to either arrest or apoptosis.

Tissue Types

• Bodies are organized into four primary tissue types: epithelial, connective, muscle, and neural tissues. Each type has unique structures and functions, contributing to organ function.

  • Epithelial Tissue: Covers surfaces, involved in protection, absorption, secretion.

  • Connective Tissue: Provides structural support and connection between tissues.

  • Muscle Tissue: Specialized for contraction, facilitating movements.

  • Neural Tissue: Composed of neurons for transmitting impulses.