Introduction to Physiology

• Biology is the scientific study of life, examining structure, function, growth, origin, evolution, and distribution of living organisms.
• It encompasses a wide range of fields, including anatomy, botany, zoology, and microbiology.
• Central to biology are key principles such as cell theory, gene theory, evolution, homeostasis, and thermodynamics.

Physiology

• Physiology studies the functions/processes of living organisms and their constituent parts.
• Explores how organisms perform vital activities, from molecular events in cells to systemic functions like respiration and circulation.
• Key areas include organ systems (e.g., cardiovascular, respiratory, digestive), cellular physiology, and comparative physiology.
• Homeostasis, the maintenance of a stable internal environment, is a central concept.
• Physiological processes are often regulated by feedback mechanisms to maintain this stability.
• Exercise physiology studies the impact of physical activity on body functions.
• Pathophysiology investigates how diseases disrupt normal physiological processes.

Evolutionary Biology

• Evolutionary biology studies the processes by which life has changed over time.
• Charles Darwin's theory of evolution by natural selection is a cornerstone.
• Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
• Genetics plays a key role, as heritable traits are passed on through genes.
• Mutation, gene flow, genetic drift, and non-random mating are other mechanisms of evolution.
• Adaptation refers to the process by which populations evolve to become better suited to their environment.
• Speciation is the process by which new species arise, often through reproductive isolation.
• Phylogenetics aims to reconstruct the evolutionary relationships between organisms using various data (e.g., DNA, morphology).

Genetics

• Genetics is the study of heredity and variation in living organisms.
• Genes, composed of DNA, are the units of heredity.
• Gregor Mendel's work laid the foundation for understanding inheritance patterns.
• The central dogma of molecular biology describes the flow of genetic information: DNA to RNA to protein.
• DNA replication is the process by which DNA is copied.
• Transcription is the process by which RNA is synthesized from a DNA template.
• Translation is the process by which proteins are synthesized from an RNA template.
• Mutations are changes in the DNA sequence and can lead to variations in traits.
• Genetic engineering involves manipulating genes for various purposes.
• Genomics is the study of entire genomes, including genes and other DNA sequences.

Cell Biology

• Cell biology studies the structure, function, and behavior of cells, the basic units of life.
• The cell theory states that all living organisms are composed of cells and that all cells arise from pre-existing cells.
• Cells are broadly classified as prokaryotic (lacking a nucleus) or eukaryotic (having a nucleus).
• Key cell structures include the plasma membrane, cytoplasm, nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosomes.
• The plasma membrane regulates the passage of substances into and out of the cell.
• The nucleus contains the cell's genetic material (DNA).
• Mitochondria are responsible for cellular respiration and ATP production.
• The endoplasmic reticulum is involved in protein synthesis and lipid metabolism.
• The Golgi apparatus processes and packages proteins.
• Lysosomes contain enzymes for breaking down cellular waste.
• Cell signaling involves the communication between cells through various signaling molecules.
• Cell division (mitosis and meiosis) is essential for growth, repair, and reproduction.
• Apoptosis is programmed cell death and plays a crucial role in development and tissue homeostasis.