Physiology Lecture Notes PDF

FLG211: INTRODUCTION TO PHYSIOLOGY, CELLS AND TISSUES DR ROSS ANDERSON DEPARTMENT OF PHYSIOLOGY FEB 2024  WHAT IS LIFE? Life comprises 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...

FLG211: INTRODUCTION TO PHYSIOLOGY, CELLS AND TISSUES DR ROSS ANDERSON DEPARTMENT OF PHYSIOLOGY FEB 2024  WHAT IS LIFE? Life comprises 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 (Britannica) 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 - K2-18b, dimethyl sulfide, methane, CO2 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  interest sake MILLER-UREY EXPERIMENT (1952) - CHICAGO Attempt to prove the validity of the abiogenesis theory (organic life forming from non-organic constituents in the primordial seas of earth (approx. 4 billion years ago) Methane (CH4), water (H2O), ammonia (NH3), and hydrogen (H2) Successfully created simple amino acids Some fundamental problems leading to multiple repeated attempts  DEFINITION OF LIFE The reality is that a definition would probably need to be incredibly complex and incorporate a variable number of the following: Maintain homeostasis Composed of cells Have a life cycle Undergo metabolism Grow Adapt to their environment Respond to stimuli Reproduce Evolve  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 Homeostasis is “constancy of the internal environment” Internal External blood loss attack External and internal stresses threaten temperature nutrients toxins infection homeostasis hormones temperature Stress induces coordinated behavioural, autonomic, CNS and endocrine changes to restore equilibrium  STRESS Stress is an organisms response to a stressor Many definitions. 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 HOMEOSTASIS MECHANISMS Homeostatic systems always contain: - Receptors - Control centre - Effectors Study.com  HOMEOSTASIS EXAMPLES Calcium is tightly regulated HOMEOSTASIS EXAMPLES UNIVERSAL PRINCIPLES OF LIFE AND CELL BIOLOGY There are a limited number of general principles that can explain the most complex processes They are based on common molecular mechanisms 1. GENETIC INFORMATION Genetic information stored as DNA sequence is duplicated and passed on to daughter cells 2. TRANSCRIPTION AND TRANSLATION Linear chemical sequences (DNA) give rise to the linear sequences and three- dimensional structures of RNAs and proteins 3. 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. It is spontaneous and reversible, and utilizes non-covalent interactions - hydrogen bonds, van der Waals forces, hydrophobic interactions etc Two types of self-assembly – intramolecular (folding) and intermolecular 3. MACROMOLECULES In biology - self-assembly of lipids to form membranes - double helical DNA through hydrogen bonding of the individual strands - assembly of proteins (folding or Introduction to Bionanotechnology pp 79–92 4. MEMBRANES Living organisms are surrounded by a membrane Made up of a lipid bilayer Following the fluid mosaic model 5. SUBCELLULAR TARGETING Spatial targeting a form of regulation Dependent on protein motifs/signals (defined as DNA or protein sequences that are associated with a biological function e.g. zinc finger motifs) Soluble proteins start at ribosomes Membrane proteins carried by vesicles to target membrane 6. MOVEMENT Cellular constituents move by diffusion, pumps, and motors 7. SIGNALLING Mechanism to receive, adapt and respond to intracellular and extracellular signals Signals can be nutrients, growth factors, hormones, neurotransmitters, and toxins 8. FEEDBACK Feedback control is the regulation of prior steps in a pathway by downstream products of that pathway