Test_1

Homeostasis

  • Definition: Homeostasis is the body's ability to maintain stable internal conditions despite internal or external changes.

  • Mechanisms of Homeostasis:

    • Negative Feedback Mechanism:

      • Reverses a trend to return to a set-point.

      • Example: If body temperature rises, mechanisms like sweating are activated to cool the body down.

    • Positive Feedback Mechanism:

      • Amplifies or intensifies a physiologic trend until a specific goal is achieved.

      • Example: During childbirth, oxytocin increases contractions to deliver the baby.

  • Components of Negative Feedback Loop:

    • Stimulus: A change that disrupts homeostasis.

    • Receptor: Senses the change in the body (e.g., temperature sensors).

    • Control Center: Integrates the information from receptors (e.g., hypothalamus, medulla oblongata).

    • Effector: Carries out the response to return to homeostasis.

Atomic Structure

  • Atoms: The smallest unit of an element, made up of protons, neutrons, and electrons.

  • Subatomic Particles:

    • Protons: Positively charged, define the identity of an element; located in the atomic nucleus.

    • Neutrons: Neutral charge; also located in the nucleus.

    • Electrons: Negatively charged; orbit the nucleus and can gain/lose energy.

  • Atomic Mass: The sum of protons and neutrons in the nucleus.

    • Atomic mass reflects the element's isotopes, which possess the same number of protons but different neutrons.

Chemical Bonds

  • Atoms bond to achieve stable arrangements of electrons, often following the octet rule.

  • Types of Chemical Bonds:

    • Covalent Bonds: Formed when two atoms share electrons (e.g., H2O).

      • Single, Double, and Triple Bonds: Indicate the number of shared electron pairs.

    • Ionic Bonds: Formed through the transfer of electrons, resulting in charged ions (cations and anions).

    • Polar and Nonpolar Covalent Bonds:

      • Nonpolar: Electrons shared equally (e.g., O2).

      • Polar: Electrons shared unequally, creating a dipole (e.g., H2O).

Water Properties

  • Hydrophilic (water-loving) and Hydrophobic (water-fearing) molecules differ in behavior in water.

  • Three Crucial Properties of Water:

    1. Polarity: Water's polar nature allows it to dissolve many substances, especially ionic and other polar molecules.

    2. Chemical Reactivity: Participates in many chemical reactions, including hydrolysis and dehydration synthesis.

    3. Thermal Stability: High heat capacity, which helps stabilize temperature changes and support life.

Cell Structure

  • Plasma Membrane: Composed of phospholipids and proteins, it regulates what enters and exits the cell.

  • Cytoplasm: Contains organelles and is the site of metabolic activities.

    • Organelles:

      • **Membrane-bound (e.g., nucleus, mitochondria) and Non-membrane organelles (e.g., ribosomes).

    • Cytoskeleton: A network of protein filaments and tubules aiding in cell shape and transport.

  • Intracellular vs. Extracellular Fluid:

    • Intracellular fluid: inside the cell; Extracellular fluid: outside the cell.

  • Vesicular Transport Mechanisms:

    • Endocytosis: Taking substances into the cell.

    • Exocytosis: Releasing substances from the cell.

Muscle Anatomy

  • Major Muscle Groups:

    • Quadriceps Femoris: Extends the knee; antagonist: hamstring group.

    • Hamstring Group: Flexes the knee; antagonist: quadriceps.

    • Iliopsoas: Flexes the hip; antagonist: gluteus maximus.

    • Gastrocnemius: Responsible for plantar flexion; antagonist: tibialis anterior.

  • Muscle Actions Include:

    • Flexion, extension, abduction, and adduction based on the anatomical position.