Human Physiology Introduction

Definition of Human Physiology

• Human physiology studies normal functions of body parts and mechanisms that sustain life.

Organization of the Human Body

• Comprised of systems, organs, tissues, and cells.

Body Systems

• Nervous system: Brain, spinal cord, and nerves.
• Endocrine system: Consists of various endocrine glands.
• Cardiovascular system: Includes the heart and blood vessels.
• Respiratory system: Comprises structures such as the nose, trachea, bronchi, and alveoli.
• Gastrointestinal system: Consists of the mouth, stomach, small intestine, and large intestine.
• Urogenital system: Includes kidneys, ureters, bladder, and urethra.
• Musculoskeletal system: Bones and muscles.
• Integumentary system: Comprises skin and associated structures.

Organs and Tissues

• Organs are made up of multiple tissues.
• Major tissue types include nervous, muscular, connective, and epithelial tissues.

Cells

• Basic living units of the body; approximately 35-40 trillion in an adult.
• Types of cells include nerve cells, muscle cells, connective tissue cells, and epithelial cells.

Composition of the Human Body

• Average adult male body composition:
  • Water: 60%
  • Proteins: 20%
  • Fat: 15%
  • Minerals: 5%
  • Carbohydrates: Minimal

Body Water Distribution

• Total body water constitutes 60%:
  • Extracellular Fluid (ECF): 20%
  • Intracellular Fluid (ICF): 40%
  • Intravascular Fluid (plasma): 5%

Normal Variations in Body Water

• Infants and children: Approximately 75% of body weight.
• Elderly: About 45%.
• Females: Roughly 50%, due to higher fat content.
• Obese individuals: Lower relative body water.

Dehydration Risks

• Children experience rapid and severe dehydration due to higher ECF ratios.

Ion Distribution in ICF and ECF

• Key cations:
  • ICF: Potassium (K+) 140 mEq/L
  • ECF: Sodium (Na+) 140 mEq/L
• Key anions:
  • ICF: Phosphate and proteins
  • ECF: Chloride (Cl-) and bicarbonate (HCO3-)

Tonicity and Ionic Composition

• Tonicity between ICF and ECF remains similar.
• ECF consists of Interstitial Fluid (ISF) and plasma, with plasma containing more proteins.

Summary

• The human body is structured as a complex organization of cells, tissues, organs, and systems, with water distribution being a critical aspect of composition and function.

Explore the basics of human physiology, including its definition, organization of the human body, and composition. Learn about the different systems, organs, tissues, and cells that make up the human body.