Lecture 2: Organisation and Complexity

Organization and Complexity of the Human Body

• The human body is the most complex machine ever to have evolved, with approximately 37 trillion cells.
• There are two major concepts: evolution ("survival of the fittest") and cell theory (all organisms are made of cells, cells are the basic units of life, and cells come from pre-existing cells that have multiplied).

Cell Types and Organization

• There are two major classes of cells:
• Cells form tissues, which are complex organizational arrangements of cells to fulfill specific functions.
• There are five basic tissue types: epithelial, connective, muscle, nervous, and adipose tissue.

Organs and Organ Systems

• Organs contain different combinations of basic tissue types, for example, the stomach.
• The stomach is an organ of the digestive system.
• The human body is made up of organ systems.

Cells and Composition

• The human body is made up of cells and water.
• Around 37 trillion cells make up the human body.
• Programmed cell death, called apoptosis, is a normal part of development, with approximately 10^11 cells dying in each adult each day and being replaced by other cells.

The Genome

• The first human genome was completed in 1990-2003, taking 13 years and costing $5 billion.
• Proteomics and polygenic risk are related concepts.

Anatomy and Physiology

• A big barrier in learning biology is language, with anatomical terminology being important.
• The human body has a high degree of complexity, with various systems working together (e.g., energy supply, scaffold, propulsion system, pumps, ventilation, plumbing, purification plant, protection, and control systems).

Control and Regulation

• The human body has a tightly controlled system, with variations in glucose levels leading to diabetes, albumin levels leading to renal disease, and electrolytes/CO2 levels leading to cardiovascular disease.
• Balancing acid and base levels is crucial, with respiratory, metabolic, and renal systems playing a role.

Surface Area and Volume

• The human body has a high surface area to volume ratio, with the lung alveoli, gut villi, and kidney microvilli increasing surface area.
• This is important for functions such as gas exchange, nutrient absorption, and waste removal.

Bioengineering and Technology

• Bioengineering is the application of engineering principles to develop innovative solutions for medical and biological systems.
• Examples of bioengineering include exoskeletons, bionic ears, and artificial hearts and kidneys.

Cell Structure and Function

• Cells are like factories, with a control centre (nucleus), protein synthesis and sorting (endoplasmic reticulum and Golgi complex), power generation (mitochondria), waste disposal (lysosomes), and transportation systems (cytoskeleton).
• Cells can grow and function independently, with many different types fulfilling various functions.