Lecture 2 Essential Functions for Sustaining Life

Aug 26, 2024

Crucial Life Functions

Introduction

  • Humans and other organisms have 6 crucial life functions to maintain life.
  • Importance of maintaining boundaries between internal and external environments to prevent equilibrium.

Maintenance of Boundaries

External vs Internal Environment

  • External Environment: Anything outside epithelial tissue.
  • Internal Environment: Begins once substances cross epithelial barriers.
  • Epithelial tissue's role is to serve as a barrier (e.g., skin, GI tract, respiratory tract).

Epithelial Tissue

  • One of four primary tissue types: connective, muscle, nervous, and epithelial.
  • Functions as a barrier to separate internal and external environments.
  • Found in the epidermis, lining of the gut tube, respiratory tract, etc.

Metabolism

  • Metabolism involves complex reactions requiring energy in the form of ATP.
  • Components needed: Nutrients, enzymes, and waste removal.

Cellular Respiration

  • Oxygen and glucose are required to produce ATP.
  • Byproducts include CO2 and heat.

Types of Metabolic Reactions

  • Catabolism: Breakdown of nutrients to release energy.
  • Anabolism: Building of complex molecules using energy.
  • Metabolism: Includes both catabolism and anabolism.

Responsiveness

  • Ability to sense and respond to external and internal stimuli.

External Stimuli

  • Includes temperature, light, sound, and pressure.

Internal Stimuli

  • Blood pressure, body temperature, ion levels, blood glucose, and pH.

Importance

  • Detect and correct small problems to prevent larger issues.
  • Nervous and endocrine systems are key systems for responsiveness.

Movement

  • Life requires motion on macro and micro scales.
  • Macro Scale: Locomotion with muscles and bones.
  • Micro Scale: Osmosis, diffusion, circulation, blood shunting, and intracellular trafficking.

Development and Growth

  • Begins with fertilization and ends with senescence.
  • Fertilization: Combination of male and female gametes to form a zygote.

Cell Addition and Growth

  • Cleavage: Rapid cell division without size increase.
  • Mitosis: Producing diploid cells.
  • Meiosis: Producing haploid gametes.

Growth Processes

  • Hyperplasia: Increase in cell number.
  • Hypertrophy: Increase in cell size.

Reproduction

  • Allows for new genetic combinations.
  • Provides genetic diversity for survival against environmental changes.
  • Red Queen Hypothesis: Describes the evolutionary advantage of sexual reproduction.

Environmental Requirements for Life

Oxygen

  • Essential for ATP production and maintaining homeothermic temperature.
  • Humans are aerobic organisms needing oxygen for basic life functions.

Oxygen Uptake

  • Involves lung function and skeletal muscle activity (e.g., diaphragm, intercostal muscles).

Oxygen Distribution

  • Biconcave red blood cells increase surface area for oxygen uptake.

Atmospheric Pressure

  • Affects oxygen availability more than oxygen levels in different elevations.
  • Atmospheric pressure decreases with elevation, affecting oxygen uptake.

Summary

  • Organ systems and environmental factors are crucial for maintaining life functions.
  • The body's complexity requires continuous adaptation to both internal and external changes.