Lecture Notes on Chemical and Cellular Levels of Life

Introduction

• Focus on chemical level, elements, molecules, and compounds in human physiology.
• Importance of chemistry knowledge for understanding human health.

Chemical Level

Atoms and Molecules

• Elements are pure substances, e.g., all iron atoms.
• Compounds are combinations of elements, e.g., water (H2O).

Importance of Elements in the Body

• Iron:
  • Sourced from diet (e.g., meat, leafy greens).
  • Essential for oxygen transport in hemoglobin in red blood cells.
  • Storage issues can lead to iron deficiency despite adequate diet.
• Oxygen:
  • Exists as molecular oxygen (O2) due to electron sharing.
  • Essential for ATP production and survival of large organisms.
  • Free radicals can be toxic; cells mitigate through enzymes and nutrients.

Cellular Level

Basic Unit of Life

• Cells as the smallest unit of life.
• Requirements for life: metabolize nutrients, reproduce, and contain genetic material (DNA/RNA).
• Viruses lack some life characteristics and are not considered alive.

Interaction with Environment

• Cells acquire elements from diet and environment, delivered by blood.
• Oxygen: Acquired by simple diffusion.
• Glucose: Requires facilitated diffusion via transport proteins.
• Water: Acquired through osmosis and aquaporin proteins.

Physiological Application

• Understanding facilitated diffusion is crucial for comprehending conditions like diabetes (broken glucose transport).

Tissue Level

Organization and Function

• Tissues are groups of similar cells working together.
• Four primary tissue types: epithelial, connective, muscle, and nervous tissue.
• Epithelial Tissue: Forms barriers, lines surfaces, and forms glands.
• Connective Tissue (CT): Includes ligaments, tendons, blood, bone, and fat.
• Muscle Tissue: Enables movement (skeletal, cardiac, smooth muscle).
• Nervous Tissue: Processes and transmits information.

Organ Level

Structure and Function

• Organs formed from two or more tissue types.
• Example: Skin (epithelial and connective tissues).
• Organs perform complex functions by combining tissue capabilities.

Organ System Level

Integration and Complexity

• Organ systems consist of two or more organs working together.
• 11 different organ systems in the human body.
• Example: Digestive system (includes stomach, intestines, pancreas, etc.).
• Organs can be part of multiple systems (e.g., pancreas in digestive and endocrine systems).

Human Body Overview

Body Plan

• Humans have a tube-within-a-tube body plan.
• Bilaterally symmetrical and bipedal.
• True homeotherms (maintain constant internal temperature).
  • Requires high metabolic rate, supported by advanced lungs and heart.

Conclusion

• Review and integrate knowledge of chemical and cellular levels.
• Apply understanding to physiological processes and diseases.

Questions for Further Thought

• Explore the implications of tissue types and organ systems in various physiological scenarios.
• Consider the evolutionary and functional significance of human body adaptations.