Anatomy and Physiology Chapter 1

Chapter 1: Body Organization and Homeostasis

• Physiology examines the function of the body, while anatomy studies its structure.
• Four major tissue types:
  • Neurons/Nervous Tissue: Facilitates communication via signals. Includes motor neurons and interneurons.
  • Muscle Tissue: Enables contraction, crucial for movement. Atrophy (muscle death) occurs if muscles are not contracted.
  • Epithelial Tissue: Involved in exchange processes, lining surfaces like skin and organs. Glands are important for releasing hormones, fluids, and enzymes to different locations (exocrine vs. endocrine).
  • Connective Tissue: Diverse group of tissues including bone, blood, and fat. Tendons connect bone to muscle, ligaments connect bone to bone.
• Homeostasis: Maintaining a stable internal environment despite external changes. Small changes are normal; large changes suggest disease.
  • Negative Feedback: A major mechanism for maintaining homeostasis. The initial input and subsequent output are opposite. Examples: sweating to cool down when hot, shivering to warm up when cold. Sensors detect change, the integrating center assesses it, and effectors make adjustments. Fever is an example of negative feedback, as the body adjusts temperature in response to infection.
  • Antagonistic Effectors: Effectors that work in opposition to produce a desired outcome(shivering and sweating)
  • Positive Feedback: A less common mechanism where input and output are the same. An example is childbirth, where contractions lead to more contractions.

Chapter 2: Cell Biology

• Electron Orbitals: Not physical entities; just regions of probability.
• Chemical Bonds: Formed due to atoms filling their outer electron shells. Noble gases do not form bonds as they already have full shells.
• Hindenburg Disaster: Explosion due to hydrogen reacting explosively with oxygen. Illustrates importance of a full outer shell and stability.
• Molecules: Two or more atoms bonded together.
  • Elements: Molecules with atoms of the same type.
  • Compounds: Molecules with atoms of different types.
• Ions: Atoms that have gained or lost electrons. They remain neutral despite the charge imbalance. Not all atoms become ions.
• Covalent Bonds: Formed by overlapping electron orbitals leading to equal or unequal sharing of electrons.
  • Nonpolar Covalent Bonds: Equal sharing of electrons.
  • Polar Covalent Bonds: Unequal sharing of electrons. Water is highly polar.
• Electronegativity: Helps predict polarity. Higher electronegativity values indicate more attraction to electrons. (HCNO)
• Hydrogen Bonds: Weak attractions between a hydrogen atom (bonded to a highly electronegative atom) and another highly electronegative atom. Not a true "bond", important for structure.
• Solubility: "Like dissolves like" (polar dissolves in polar, nonpolar dissolves in nonpolar).
• Water: Universal solvent, polar, and essential for life. Hydrophilic molecules dissolve, hydrophobic molecules do not.
• Carbohydrates: Monosaccharides (single sugars) with a 1:2:1 ratio of carbon, hydrogen, and oxygen. Stored as glycogen for short-term energy.
  • Glycogen depletion and dietary changes are related to water weight loss.
• Lipids: Long-term energy storage, including saturated and unsaturated fats.
  • Saturated fats are tightly packed and contribute to heart disease.
  • Unsaturated fats have more space and are typically liquid at room temperature.
  • Phospholipids: Essential for cell membrane formation (polar and nonpolar regions).
  • Steroids: Derived from cholesterol, include sex hormones.
• Proteins: Polymers of amino acids, crucial for structure and function.
  • 20 different amino acids with varying side chains.
  • Protein structure: Primary (sequence), secondary (folds), tertiary (3D shape), and quaternary (multiple chains).
  • Denaturation: Loss of tertiary structure due to high temperatures.
• Nucleotides: Building blocks of DNA and RNA.
  • Different bases distinguish nucleotides (GCAT)
  • DNA and RNA differ in sugar type.
  • RNA, uses a slightly different sugar, and has a different base (U instead of T).
  • Chromosomes: DNA and protein complex. Genes code for proteins.
• DNA to Protein:
  • Transcription: DNA is transcribed to pre-mRNA in nucleus; involves RNA polymerase and base pairing.
  • Translation: Pre-mRNA processed to mRNA; mRNA translated to protein using ribosomes, tRNA, and codons (AUG-start; UAA, UAG, UGA-stop) in the cytoplasm.
• Human Genome: 98.5% of human DNA does not code for proteins.
• Protein Modification: Important for diversity.
• Thermodynamics: The laws of energy are essential for all reactions.
  • First Law: Energy is conserved.
  • Second Law: Every energy transfer produces some unusable energy —heat.
• Reactions:
  • Endergonic: Require energy input (products have more energy than reactants).
  • Exergonic: Release energy (reactants have more energy than products).
  • Coupled Reactions: Link exergonic and endergonic reactions for endergonic to happen.
• Enzymes: Biological catalysts that lower activation energy, speed up reactions.
• Activation Energy: Needed to start a reaction (similar to giving a reactant a “push” or changing its shape).
  • Enzymes lower activation energy in biological reactions, thus reaction can proceed faster.
• Ligands: Substances that bind to receptors.
• Metabolic Pathways: Series of linked reactions. Feedback inhibition regulates pathways.
• ATP: Energy currency of the cell. Hydrolysis releases energy.
• Cellular Respiration: Metabolic pathway that generates ATP. Glycolysis is first step.