FLG 211

• FLG211: INTRODUCTION TO PHYSIOLOGY, CELLS AND TISSUES
• DR ROSS ANDERSON
• DEPARTMENT OF PHYSIOLOGY
• What we are going to cover

  • Introduction to physiology
  • Homeostasis
  • The structure of cells, and intracellular organelles
  • Cell division
  • Structure and function of tissues
  • Structure and function of the cytoskeleton
• Life


  • Living beings assigned to groups (called taxa)
  • Each individual is composed of one or more minimal living units, called cells, and is capable of transformation of carbon-based and other compounds (metabolism), growth, and participation in reproductive acts
• There are many ways to define life, and all have drawbacks
• Some scientists and philosophers of science suggest that it is not possible to define life
• Why do we need to define life?

  • To provide defendable objective criteria for searches for life on other planets
  • To recognize critical distinctions between machine life and robots
  • To provide insight into laboratory approaches to creating test-tube life
  • To understand the profound changes that occurred during the origin of life
  • To clarify the central process of the discipline of biology
• Miller-Urey Experiment (1952) - Chicago


  1. Attempt to prove the validity of the abiogenesis theory

  2. Methane (CH4), water (H2O), ammonia (NH3), and hydrogen (H2)

  3. Successfully created simple amino acids

  4. Some fundamental problems leading to multiple repeated attempts
• Definitions of life


  • Metabolic
  • Physiological
  • Biochemical
  • Genetic
• Often, definitions of life are biased by the research focus of the person making the definition
• Definitions of life may need to incorporate

  • Maintain homeostasis
  • Composed of cells
  • Have a life cycle
  • Undergo metabolism
  • Grow
  • Adapt to their environment
  • Respond to stimuli
  • Reproduce
  • Evolve
• Biological/Life Sciences


  • Anatomy
  • Physiology
  • Molecular biology
  • Biochemistry
  • Ecology
  • Taxonomy
  • Ethology

  
• Physiology


  • The study of function of living bodies and their parts
  • Central to physiological functioning are biophysical, biochemical, homeostatic and cell-cell communication processes
  • The survival of the organism depends on the integrated activity of all the organ systems, often coordinated by the endocrine and nervous systems (to maintain homeostasis)
• Homeostasis


  • Constancy of the internal environment
  • External and internal stresses threaten homeostasis
  • Stress induces coordinated behavioural, autonomic, CNS and endocrine changes to restore equilibrium
• Stress


  • An organism's response to a stressor
  • Selye defined stress as the "nonspecific response of the body to any demand made upon it"
  • Acute threats to the homeostasis of an organism, be it real (physical) or perceived (psychological)
  • Stressors can be changes in the internal or external environment, experiences, or demanding events
  • Biochemical response to stress
  • Psychological stress
• Homeostatic systems


  • Contain receptors
  • Contain a control centre
  • Contain effectors
• Homeostasis examples


  • Calcium is tightly regulated

  
• Allostasis


  • Permits variation in the face of environmental challenges
  • Reflects changes to the homeostatic set points
  • A physiological mechanism of regulation in which the human body anticipates and adjusts its energy use according to environmental demands
• Allostatic load


  • The breakdown of the body's defence mechanisms in response to chronic exposure to stress
  • The cost or the price the body may have to pay for being forced to adapt to an adverse or deleterious physiological or physical situation
• Chronically elevated allostatic load can lead to serious adverse health outcomes, such as hypertension, diabetes, obesity, coronary heart disease, neurodegenerative disorders
• Universal principles of life and cell biology

  • Genetic information
  • Transcription and translation
  • Macromolecules
  • Membranes
  • Subcellular targeting
  • Movement
  • Signalling
  • Feedback
• Genetic information


  Genetic information stored as DNA sequence is duplicated and passed on to daughter cells

  
• Transcription and translation


  Linear chemical sequences (DNA) give rise to the linear sequences and three-dimensional structures of RNAs and proteins

  
• Macromolecules


  • Macromolecules are build by combining subunits
  • Allows for diversity from identical building blocks
  • Self-assemble
  • Self-assembly refers to the ability of molecules to arrange themselves into defined structures without guidance or help from an outside source
  • Two types of self-assembly – intramolecular (folding) and intermolecular
• Self-assembly in biology


  • Self-assembly of lipids to form membranes
  • Double helical DNA through hydrogen bonding of the individual strands
  • Assembly of proteins (folding or)

  
• Membranes


  • Living organisms are surrounded by a membrane
  • Made up of a lipid bilayer
  • Following the fluid mosaic model
• Subcellular targeting


  • Spatial targeting a form of regulation
  • Dependent on protein motifs/signals
  • Soluble proteins start at ribosomes
  • Membrane proteins carried by vesicles to target membrane
• Movement


  Cellular constituents move by diffusion, pumps, and motors
• Signalling


  • Mechanism to receive, adapt and respond to intracellular and extracellular signals
  • Signals can be nutrients, growth factors, hormones, neurotransmitters, and toxins
• Feedback


  Feedback control is the regulation of prior steps in a pathway by downstream products of that pathway