Fundamental Concepts in Biology

• Biology is the scientific study of life.
• Physiology is the study of the normal functions within living beings.

Fundamental Concepts in Biology

• Cell theory states the cell is the basic unit of life.
• All living organisms are composed of cells
• All cells arise from pre-existing cells.
• Genes are the basic units of heredity and are composed of DNA.
• Evolution is the change in the heritable characteristics of biological populations over successive generations.
• Homeostasis is the ability of an organism to maintain a stable internal environment despite changes in external conditions.
• Life requires energy, often obtained through metabolic processes like photosynthesis and cellular respiration.

Levels of Biological Organization

• Atoms combine to form molecules, such as water, proteins, carbohydrates, and lipids, which are essential for life.
• Cells are the basic structural and functional units of life.
• Tissues are groups of similar cells performing a specific function.
• Organs are structures composed of different tissues working together.
• Organ systems are groups of organs that cooperate to perform major bodily functions.
• Organisms are individual living entities.
• Populations are groups of individuals of the same species living in the same area.
• Communities are populations of different species living and interacting in the same area.
• Ecosystems are communities of organisms interacting with their physical environment.
• Biosphere includes all of the ecosystems on Earth.

Key Biological Processes

• Photosynthesis is the process by which plants and some bacteria convert light energy into chemical energy in the form of glucose.
• Cellular respiration is the process by which cells break down glucose to produce ATP, the energy currency of the cell.
• DNA replication is the process by which DNA is duplicated.
• Transcription is the process by which RNA is synthesized from a DNA template.
• Translation is the process by which proteins are synthesized from RNA.

Major Branches of Biology

• Biochemistry is the study of the chemical substances and vital processes occurring in living organisms.
• Genetics is the study of heredity and variation of inherited characteristics.
• Ecology is the study of the interactions between organisms and their environment.
• Evolutionary biology is the study of the evolutionary processes that have produced the diversity of life on Earth.
• Microbiology is the study of microorganisms such as bacteria, viruses, and fungi.
• Botany is the study of plants.
• Zoology is the study of animals.

Introduction to Physiology

• Physiology seeks to explain the physical and chemical mechanisms responsible for the origin, development, and progression of life.
• It deals with the functions and activities of living matter, such as organs, tissues, or cells, and the physical and chemical phenomena involved.

Levels of Physiological Study

• Molecular physiology examines the molecular mechanisms underlying physiological processes.
• Cellular physiology studies the functions of cells, including transport, signaling, and metabolism.
• Systems physiology focuses on the functions of organ systems, such as the cardiovascular, respiratory, and nervous systems.
• Organismal physiology studies the integrated functions of the whole organism.
• Evolutionary physiology explores how physiological processes evolve over time.

Core Physiological Concepts

• Homeostasis is the maintenance of a stable internal environment.
  • This is essential for cell function and survival.
  • It involves regulatory mechanisms such as feedback loops.
• Feedback mechanisms are processes that regulate physiological variables.
  • Negative feedback involves a response that opposes the original stimulus, maintaining stability, for example, body temperature regulation.
  • Positive feedback involves a response that amplifies the original stimulus, leading to a rapid change, for example, blood clotting.
• Transport is the movement of substances across cell membranes.
  • Passive transport does not require energy (e.g., diffusion, osmosis).
  • Active transport requires energy to move substances against their concentration gradients.
• Cell signaling is communication between cells.
  • Hormones are chemical messengers secreted into the bloodstream.
  • Neurotransmitters are chemical messengers that transmit signals across synapses.
  • Cytokines are signaling molecules that mediate and regulate immunity, inflammation and hematopoiesis.
• Energy balance is the balance between energy intake and energy expenditure.
  • Metabolism is the sum of all chemical reactions in the body.
  • Basal metabolic rate (BMR) is the energy expended by the body at rest.

Major Organ Systems and Their Functions

• The cardiovascular system transports oxygen, nutrients, and hormones throughout the body and removes waste products.
  • The heart pumps blood.
  • Blood vessels constitute Arteries, veins, and capillaries.
  • Blood carries oxygen and nutrients.
• The respiratory system exchanges gases between the body and the environment.
  • The lungs facilitate gas exchange.
  • Airways include Trachea, bronchi, and bronchioles.
• The nervous system controls and coordinates bodily functions.
  • The brain is the central control organ.
  • The spinal cord relays signals between the brain and body.
  • Nerves transmit signals throughout the body.
• The endocrine system regulates bodily functions through hormones.
  • Glands secrete hormones, these include the pituitary, thyroid, and adrenal glands
• The digestive system breaks down food and absorbs nutrients, it consists of:
  • Mouth, esophagus, stomach, small intestine, large intestine, liver, and pancreas.
• The urinary system filters waste products from the blood and eliminates them from the body, which comprises:
  • Kidneys, ureters, bladder, and urethra.
• The musculoskeletal system provides support, movement, and protection, consisting of:
  • Bones, muscles, and joints.
• The immune system protects the body from infection and disease, it is made up of:.
  • White blood cells, antibodies, and the lymphatic system.
• The reproductive system enables reproduction.
  • Male: Testes, sperm.
  • Female: Ovaries, eggs, uterus.

Techniques in Physiology

• Experimental design involves controlled experiments to test hypotheses.
• Imaging techniques like MRI, CT scans, and PET scans are used to visualize body structures and functions.
• Electrophysiology measures electrical activity in cells and tissues (e.g., EEG, ECG).
• Molecular techniques, like PCR, Western blotting, and ELISA are used to study gene expression and protein function.

Integration of Biology and Physiology

• Physiology relies on biological principles to explain how living organisms function.
• Understanding biology provides the foundation for comprehending physiological processes at all levels of organization.
• Knowledge of physiology can offer insights into the functional consequences of biological phenomena from molecules to ecosystems.