BIO 240 LECTURE 1

Homeostasis

• Definition: The ability of an organism to maintain internal stability despite external changes.

• Importance: Essential for proper cell function and overall organismal health.

The Role of the Cell Membrane

• Function: Acts as a selective barrier to regulate what enters and exits the cell, protecting cell contents.

• Structure: Composed of a phospholipid bilayer, with embedded proteins serving various functions.

Introduction to the Scientific Method

• Science evolves as it attempts to understand nature; key scientific functions include:

  • Detailed Observations: Collecting accurate and thorough data.

  • Hypothesis Formation: Proposing potential explanations based on observations.

  • Experiment Development: Creating tests to validate or refute the hypothesis.

  • Data Analysis: Collecting and interpreting the results from experiments.

  • Bias Detection: Assessing if results are influenced by any preconceived notions or preferences.

  • Alternate Proposals: Suggesting new hypotheses based on findings.

  • Hypothesis Testing: Continually testing to achieve supported conclusions.

• Hypotheses that are well-supported can develop into theories; those with exceptional support can evolve into laws.

• Example Experiment:

  • Experiment 1: Rat ovaries removal → increased appetite and obesity; hypothesized estrogen loss spiked appetite.

  • Experiment 2: Controlled food intake after ovary removal → rats became sedentary and obese, suggesting that estrogen loss leads to both decreased activity and weight gain.

  • Better Conclusion: Low estrogen leads to weight gain regardless of caloric intake.

Correlation vs. Causation

• Correlation: Indicates a mutual relationship between two variables.

• Important Note: Correlation does not imply causation.

Biology & Anatomy

• Biology: The study of life.

• Anatomy: Study of body structure and arrangement.

  • Macroscopic Structure: Gross Anatomy.

  • Microscopic Structure: Histology (study of tissues) and Cytology (study of cells).

• Physiology: The study of functions of body parts.

• Living organisms are self-organizing and self-maintaining; this state is referred to as Homeostasis.

Characteristics of Life

• Key traits that help maintain homeostasis:

  • Absorption: Movement of nutrients into the bloodstream.

  • Circulation: Movement of body fluids across different regions.

  • Conductivity: Capacity to transmit electrical impulses, especially in nerve and muscle cells.

  • Digestion: Breaking down complex food into simpler absorbable substances.

  • Excretion: Removal of waste products from the body.

  • Growth: Increase in size or number of cells.

  • Maintenance of Boundaries: Cell membranes and skin separating inside from outside.

  • Movement: Essential for life processes, including internal and external movements.

  • Reproduction: Formation of new individuals or cells for growth/repair.

  • Respiration: Exchange of gases (O2 & CO2) between organisms and environment.

  • Responsiveness/Irritability: Sensing and responding to environmental changes.

  • Secretion: Production of useful substances (hormones, etc.).

Levels of Organization in Body

1. Atom

2. Molecule

3. Organelle

4. Cell

5. Tissue

6. Organ

7. Organ System

8. Organism

Organ Systems Overview

• Major systems include:

  • Urinary

  • Cardiovascular

  • Respiratory

  • Endocrine

  • Digestive

  • Reproductive

  • Integumentary

  • Nervous

  • Lymphatic

  • Skeletal

  • Muscular

  • Immune

Integumentary System

• Components: Hair, Skin, Nails

• Functions:

  • Protects body from external environment.

  • Produces Vitamin D.

  • Retains water.

  • Regulates body temperature.

Nervous System

• Components: Brain, Spinal Cord, Nerves

• Functions:

  • Regulates body functions and movements.

  • Provides sensations and higher mental functions via nerve impulses.

Muscular System

• Components: Skeletal muscles

• Functions:

  • Produces movement.

  • Controls body openings.

  • Generates heat.