BIOL 205 Principles of Human Biology PDF

University of Balamand Faculty of Health Sciences BIOL 205 – Principles of Human Biology CHAPTER 1- INTRODUCTION: A VIEW OF LIFE Dr. Espérance Debs  Outline 2  Biology and life  Characteristics of living organisms  Growth and d...

University of Balamand Faculty of Health Sciences BIOL 205 – Principles of Human Biology CHAPTER 1- INTRODUCTION: A VIEW OF LIFE Dr. Espérance Debs  Outline 2  Biology and life  Characteristics of living organisms  Growth and development  Reproduction  Metabolism and Homeostasis  ‘Locomotion’  Reaction to stimuli  Adaptation  Signaling  Building blocks of the human body Introduction: a view of life  What is Biology? 3  Biology is the “Science of Life”: 1. Understanding humans and other organisms 2. Examining interrelationships of organisms 3. Studying cellular organization 4. Studying flow of energy in living organisms 5. Taking a close look at the evolution of life across time Introduction: a view of life  Why do we study Biology? 4  The basis to understanding ourselves & our environment  Providing technology for survival:  e.g. heart transplant surgeries  Providing techniques for therapy:  e.g. gene therapy  Increase resources:  e.g. world food production by genetically manipulating crops Introduction: a view of life  What is life? 5  Living things share common characteristics: 1. They grow and develop 2. They are able to reproduce 3. They regulate their own metabolism 4. They are capable of moving and responding to stimulus 5. They can adapt to environmental changes Introduction: a view of life  Growth and Development 6  Growth is an increase in the size of individual cells or in the number of cells of a living organism  Growth may be homogenous or heterogenous across organisms ◼ e.g. Trees keep growing while animals reach a final size  Development includes all changes taking place in an organism during his lifetime: ◼ e.g. Humans: fertilized embryo to adulthood Introduction: a view of life  Growth and Development 7 Introduction: a view of life  Ability to Reproduce 8  Reproduction is a characteristic that constitutes the very essence of life  Reproduction may be sexual where an egg is fertilized by a sperm leading to a unique offspring  Reproduction may be asexual (e.g. amoeba splits into two identical amoeba) Introduction: a view of life  Asexual and Sexual Reproduction 9 Asexual Reproduction Sexual Reproduction Introduction: a view of life  Metabolism and Homeostasis 10  Metabolism is the sum of chemical activities of an organism  Metabolism includes energy transformation, growth, repair  Metabolism is carefully self-regulated to maintain a balanced internal state known as “homeostasis”  Example of homeostasis is blood glucose control Introduction: a view of life  Metabolism and Homeostasis 11 3 Input: Control Information 4 Output: center sent along Information sent afferent along efferent pathway to pathway to Receptor (sensor) Effector 2 Change detected by receptor 5 Response of Stimulus: effector feeds 1 Produces back to change influence in variable magnitude of Variable (in homeostasis) stimulus and returns variable to homeostasis Introduction: a view of life  Homeostasis: Negative Feedback 12 Introduction: a view of life  ‘Locomotion’ 13  Simpler organisms  Amoeboid movement  The beating of cilia or flagella  Animals  Move by contracting muscles  Some are sessile and have cilia or flagella  Plants respond to light, water, etc Introduction: a view of life  Response to stimuli 14  Stimulus is a physical or chemical change in the internal or external environment  All forms of life respond to stimuli  The organism responds to, for example, changes in:  Light  Temperature, pressure, or sound  The chemical composition of soil Introduction: a view of life  Ability to Adapt 15  Another characteristic of life is the ability to evolve and adapt to changes  Characteristics that enhance an organism’s ability to survive in a particular environment  Adaptation may be structural, physiological, behavioral,…etc  E.g. vasoconstriction in cold weather Introduction: a view of life  Transmitting Information 16  To maintain homeostasis, cells must communicate among each other in what is known as cellular signaling  Cells may communicate through hormones, neurotransmitters, or other Growth factors binding to capillary cells messengers Introduction: a view of life  Life and chemistry 17  Life, in its many forms, is a result of the many chemical reactions and interactions that take place in each and every cell.  Individual atoms and molecules found in living organisms are the basis of life.  The difference in complexity of living organisms can be explained by understanding the ways in which simple elements combine in increasingly complex ways to produce new structures, and new emergent properties. Introduction: a view of life  Biological Organization 18  Chemical level: Atoms & Molecules  Cellular level  Tissues and organs  Organism and species  Populations and community  Ecosystem  Biosphere Introduction: a view of life  Building blocks of the human body 19 Atoms Molecules Proteins, Nucleic acids, Lipids, Carbohydrates Cells Organism Tissues Organs Introduction: a view of life  Atoms 20  Atoms are the building blocks or basic units of molecules  The atom is unimaginably tiny  One type of element differs from another by virtue of the number of sub-atomic particles  3 sub-atomic particles: Electrons, protons, neutrons  Electrons are particles carrying a negative charge  Protons are particles carrying a positive charge  Neutrons are uncharged particles Introduction: a view of life  Molecules 21  Substance formed of more than one atom  E.g. Table salt formed of sodium and chlorine 4 types of organic molecules are very important: ◼ Proteins ◼ Nucleic acids ◼ Lipids ◼ Carbohydrates Introduction: a view of life  Cells and Tissues 22  A Cell:  Isthe basic unit of life  Consists of atoms and molecules  Associates with other cells to form tissues in multicellular organisms  Tissue  In animals, an example is muscle  In plants, an example is epidermis  Tissues are organized into organs  Tissues and organs form organ systems Introduction: a view of life  Organs and organ systems 23  An organ: Several tissues acting as a whole to establish a well defined function  E.g. Heart, lungs, eyes…  Organ systems: Several organs that act together to fulfill a group of functions  E.g. Nervous, digestive, and immune systems… Introduction: a view of life  Populations, Communities, Ecosystems 24  Population:  Members of a species that live in the same area at the same time  Community:  Populations that live together and interact  Ecosystem  A community and the environment Introduction: a view of life