Introduction to Anatomy

• Anatomy is the study of the structure of living organisms, including cells, tissues, organs, and systems

Anatomical Terminology

• Anatomical position is a standardized reference for consistent body descriptions
• In anatomical position, the body is upright, facing forward, arms at the sides, palms forward
• Superior refers to structures closer to the head, while inferior refers to structures closer to the feet
• Anterior describes structures toward the front, and posterior describes structures toward the back
• Medial means closer to the midline, and lateral means farther from the midline
• Proximal is closer to the point of attachment/origin, and distal is farther from the point of attachment/origin
• Sagittal planes divide the body into left and right sections
• Coronal (or frontal) planes divide the body into anterior and posterior sections
• Transverse (or axial) planes divide the body into superior and inferior sections

Levels of Organization

• The body is organized from simplest to most complex: atoms, molecules, cells, tissues, organs, organ systems, and organism
• Cells are the basic structural and functional units
• Tissues are groups of similar cells performing specific functions
• The four main tissue types are: epithelial, connective, muscle, and nervous
• Organs are composed of two or more tissue types performing specific functions
• Organ systems consist of different organs working together for a common purpose
• The organism is a complete living being, with all structural levels coordinated

Skeletal System

• The skeletal system provides support, protection, and movement
• The skeletal system includes bones, cartilage, ligaments, and joints
• The axial skeleton includes the skull, vertebral column, and rib cage
• The appendicular skeleton includes limb bones, pectoral girdle, and pelvic girdle
• Bones are classified by shape: long, short, flat, irregular, and sesamoid

Muscular System

• The Muscular system is responsible for movement, posture, and heat production
• The Muscular system includes skeletal muscles, smooth muscles, and cardiac muscle
• Skeletal muscles attach to bones via tendons for voluntary movements

Nervous System

• The Nervous system controls and coordinates bodily functions and responds to stimuli
• The Nervous system includes the brain, spinal cord, and nerves
• The central nervous system (CNS) consists of the brain and spinal cord
• The peripheral nervous system (PNS) includes all neural tissue outside the CNS
• Neurons are the basic functional units of the nervous system

Cardiovascular System

• The Cardiovascular system transports oxygen, nutrients, hormones, and waste
• The Cardiovascular system includes the heart, blood vessels (arteries, veins, capillaries), and blood
• The heart pumps blood through the circulatory system

Respiratory System

• The Respiratory system is responsible for gas exchange: taking in oxygen, releasing carbon dioxide
• The Respiratory system includes the lungs, trachea, bronchi, and diaphragm

Digestive System

• The Digestive system breaks down food into absorbable nutrients
• The Digestive system includes the mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, and gallbladder

RNA

• RNA (Ribonucleic acid) is a nucleic acid crucial for roles like gene expression
• RNA is typically single-stranded, unlike double-stranded DNA
• RNA contains ribose sugar, DNA contains deoxyribose sugar
• RNA uses uracil (U) instead of thymine (T) in DNA
• The primary role of RNA is to translate DNA information into proteins

Types of RNA

• Messenger RNA (mRNA) carries genetic information from DNA to ribosomes in the cytoplasm
• mRNA serves as a template for protein synthesis
• Transfer RNA (tRNA) transports amino acids to ribosomes for protein synthesis
• Each tRNA carries a specific amino acid and recognizes a codon on mRNA
• Ribosomal RNA (rRNA) is a structural component of ribosomes
• rRNA provides a platform for mRNA and tRNA interaction during translation
• MicroRNA (miRNA) are small, non-coding RNA molecules that regulate gene expression
• miRNA binds to mRNA, leading to degradation or translational repression
• Small interfering RNA (siRNA) are double-stranded RNA that trigger RNA interference
• siRNA can silence gene expression by targeting mRNA for degradation

Transcription

• Transcription is the process of synthesizing RNA from a DNA template
• RNA polymerase is the enzyme responsible for transcription
• Transcription begins when RNA polymerase binds to a promoter region on DNA
• RNA polymerase moves along the DNA template, synthesizing a complementary RNA molecule
• After transcription, the RNA molecule may undergo processing, including splicing, capping, and tailing

Translation

• Translation is the process of synthesizing proteins from mRNA
• Translation occurs on ribosomes in the cytoplasm
• mRNA binds to the ribosome, tRNA brings amino acids based on the mRNA sequence
• Each codon (three-nucleotide sequence) on mRNA corresponds to a specific amino acid
• The ribosome moves along the mRNA, adding amino acids to the polypeptide chain
• Translation continues until a stop codon is reached

RNA Regulation

• RNA plays a critical role in regulating gene expression
• Regulatory RNAs (miRNA, siRNA) control mRNA stability and translation
• RNA-binding proteins regulate RNA function by binding to specific RNA sequences/structures
• RNA modifications (methylation, acetylation) can affect RNA stability and function

Chemistry of Life

• Chemistry of life involves the study of chemical processes and substances within organisms
• It includes the study of biomolecules like carbohydrates, lipids, proteins, and nucleic acids

Basic Chemical Principles

• Atoms are the basic units of matter
• Atoms consist of protons, neutrons, and electrons
• Elements are pure substances composed of one type of atom
• Molecules are formed when two or more atoms are held together by chemical bonds
• Chemical bonds include ionic bonds, covalent bonds, and hydrogen bonds

Water

• Water is essential for life
• Water is a polar molecule and an excellent solvent
• Water has high heat capacity, regulating temperature in living organisms
• Water participates in many biochemical reactions

Carbohydrates

• Carbohydrates are a primary energy source for living organisms
• Carbohydrates include sugars, starches, and cellulose
• Monosaccharides are simple sugars (e.g., glucose, fructose)
• Disaccharides are composed of two monosaccharides (e.g., sucrose, lactose)
• Polysaccharides are complex carbohydrates composed of many monosaccharides (e.g., starch, glycogen, cellulose)

Lipids

• Lipids include fats, oils, phospholipids, and steroids
• Lipids provide insulation, energy storage, and structural components of cell membranes
• Triglycerides consist of glycerol and three fatty acids
• Phospholipids are major components of cell membranes
• Steroids include cholesterol and hormones

Proteins

• Proteins are essential for structural support, enzymes, transport, and immune defense
• Proteins are composed of amino acids
• Amino acids are linked together by peptide bonds
• Proteins have four levels of structure: primary, secondary, tertiary, and quaternary

Nucleic Acids

• Nucleic acids include DNA and RNA
• Nucleic acids store and transmit genetic information
• DNA contains the genetic instructions for the development and function of living organisms
• RNA plays a role in protein synthesis
• Nucleotides are the building blocks of nucleic acids
• Nucleotides consist of a sugar, a phosphate group, and a nitrogenous base

Enzymes

• Enzymes are biological catalysts that speed up chemical reactions in living organisms
• Enzymes are proteins with specific active sites that bind to substrates
• Enzymes lower the activation energy of biochemical reactions
• Enzyme activity is affected by temperature, pH, and enzyme inhibitors

Metabolism

• Metabolism is the sum of all chemical reactions that occur in a living organism
• It includes catabolism (breakdown of complex molecules) and anabolism (synthesis of complex molecules)
• Energy is required for metabolic processes
• ATP (adenosine triphosphate) is the main energy currency of the cell
• Metabolic pathways are sequences of chemical reactions catalyzed by enzymes

Anatomy is the study of the structure of living organisms. This includes cells, tissues, organs, and systems. Anatomical position is a standardized way of observing and orienting the body, ensuring consistency in descriptions.