Comprehensive Study Guide for Anatomy & Physiology Final Exam

Muscle Tissue

Properties of Muscle Tissue

Muscle tissue possesses four key properties that enable its function in the body:

• Excitability: The ability to receive and respond to stimuli, typically from nervous impulses.

• Contractility: The ability to shorten forcibly when stimulated, generating force.

• Extensibility: The ability to be stretched or extended without damage.

• Elasticity: The ability to return to original length after stretching or contracting.

Excitability is also a property of nervous tissue, while contractility is unique to muscle tissue.

Sarcomere Structure and Function

The sarcomere is the basic contractile unit of striated muscle fibers. It is defined as the segment between two Z discs.

• Z disc: Defines the boundary of each sarcomere.

• A band: Contains thick filaments (myosin); remains the same length during contraction.

• I band: Contains thin filaments (actin); shortens during contraction.

• H zone: Central region of A band with only thick filaments; shortens during contraction.

• M line: Center of the sarcomere; holds thick filaments together.

During muscle contraction, the sarcomere shortens as thin filaments slide past thick filaments, pulling Z discs closer together. The I band and H zone decrease in width, while the A band remains unchanged.

Motor Unit and Neuromuscular Junction

• Motor Unit: A single motor neuron and all the muscle fibers it innervates.

• Neuromuscular Junction (NMJ): The synapse where a motor neuron communicates with a muscle fiber. Structures include the axon terminal, synaptic cleft, and motor end plate.

• Stimulation of Contraction: An action potential in the motor neuron releases acetylcholine, which binds to receptors on the muscle fiber, initiating contraction.

Key Terms in Muscle Contraction

• Power Stroke: The action of myosin pulling actin filaments toward the center of the sarcomere.

• Cross-Bridge Formation: The attachment of myosin heads to actin filaments.

• Depolarization: The inside of the muscle fiber membrane becomes less negative due to Na+ influx.

• Repolarization: Restoration of the resting membrane potential, primarily by K+ efflux.

Skeletal Muscle Fiber Structure

• Sarcolemma: The plasma membrane of a muscle fiber.

• Sarcoplasmic Reticulum (SR): Specialized endoplasmic reticulum that stores and releases Ca2+ for muscle contraction.

• T Tubule: Invaginations of the sarcolemma that transmit action potentials into the muscle fiber.

Joints and Articulations

Types of Articulations

• Sutures: Immovable joints between skull bones.

• Gomphoses: Peg-in-socket joints, such as teeth in alveolar sockets.

• Symphysis: Slightly movable joints with fibrocartilage, e.g., pubic symphysis.

• Syndesmoses: Joints with bones connected by ligaments, allowing limited movement (e.g., distal tibiofibular joint).

Muscle Fiber Types

• Slow Oxidative Fibers: Contract slowly, use aerobic respiration, fatigue-resistant.

• Fast Glycolytic Fibers: Contract quickly, use anaerobic glycolysis, fatigue rapidly.

• Fast Oxidative Fibers: Intermediate properties; contract quickly, use aerobic metabolism, moderately fatigue-resistant.

Nervous System Fundamentals

Action Potential Steps

1. Resting State: Membrane potential at approximately -70 mV; Na+ and K+ channels closed.

2. Depolarization: Na+ channels open, Na+ enters cell; membrane potential becomes positive.

3. Repolarization: Na+ channels inactivate, K+ channels open, K+ exits cell; membrane potential returns negative.

4. Hyperpolarization: K+ channels remain open, membrane potential becomes more negative than resting.

5. Return to Resting Potential: Na+/K+ pump restores ion gradients.

Typical voltages: Resting (-70 mV), threshold (~-55 mV), peak (+30 mV).

Sodium-Potassium Pump

• Maintains resting membrane potential by pumping 3 Na+ out and 2 K+ in per ATP hydrolyzed.

• Essential for restoring ion gradients after action potentials.

Equation:

$3\ \mathrm{Na}^+_{\text{in}} + 2\ \mathrm{K}^+_{\text{out}} + \mathrm{ATP} \rightarrow 3\ \mathrm{Na}^+_{\text{out}} + 2\ \mathrm{K}^+_{\text{in}} + \mathrm{ADP} + \mathrm{P}_i$

Refractory Periods

• Absolute Refractory Period: No new action potential can be initiated, regardless of stimulus strength.

• Relative Refractory Period: A stronger-than-normal stimulus can initiate another action potential.

Saltatory Conduction

• Action potentials jump from node to node (Nodes of Ranvier) in myelinated axons, increasing conduction speed.

• Requires myelin sheath for insulation.

Neurotransmitters and Synapses

• Acetylcholine: Released at NMJ, binds to receptors on muscle, triggers depolarization and contraction.

• Synapse: Junction between two neurons or a neuron and effector; ensures one-way transmission of nerve impulses.

Neuroglia and Neuron Structure

• Astrocytes: Star-shaped glial cells in CNS; support neurons, maintain blood-brain barrier, regulate ion balance.

• Neuron Parts: Cell body (soma), dendrites (receive signals), axon (transmits signals).

Nervous System Functions

• Sensory Input: Detects changes inside and outside the body.

• Integration: Processes and interprets sensory input.

• Motor Output: Activates effector organs (muscles/glands) in response.

Peripheral vs. Central Nervous System Regeneration

• PNS neurons can regenerate due to Schwann cells forming regeneration tubes.

• CNS neurons have limited regeneration due to inhibitory factors and lack of supportive structures.

Brain and Reflexes

• Brain Stem Parts: Midbrain (visual/auditory reflexes), pons (breathing regulation), medulla oblongata (vital centers).

• Reflex Arc Steps: Receptor → Sensory neuron → Integration center → Motor neuron → Effector.

Special Senses and Cranial Nerves

• Hearing Structures: Cochlea, auditory ossicles, tympanic membrane.

• Vision Structures: Retina, lens, cornea, optic nerve.

• Cranial Nerves: Twelve pairs, each with specific sensory/motor functions (e.g., optic nerve for vision, vagus nerve for parasympathetic control).

Human Body Organization and Homeostasis

Levels of Organization

• Chemical → Cellular → Tissue → Organ → Organ System → Organism

Anatomical Terms

• Directional Terms: Anterior/posterior, superior/inferior, medial/lateral, proximal/distal.

• Planes: Sagittal, frontal (coronal), transverse.

Homeostasis and Feedback

• Homeostasis: Maintenance of a stable internal environment.

• Feedback System Parts: Receptor, control center, effector.

• Negative Feedback: Reverses a change (e.g., body temperature regulation).

• Positive Feedback: Enhances a change (e.g., blood clotting, labor contractions).

Chemistry of Life

Atoms, Elements, and Bonds

• Atom: Smallest unit of an element.

• Proton: Positively charged particle in nucleus.

• Neutron: Neutral particle in nucleus.

• Electron: Negatively charged particle in electron cloud.

• Isotope: Atoms of the same element with different numbers of neutrons.

• Ion: Atom with a net charge due to loss/gain of electrons.

• Atomic Number: Number of protons.

• Mass Number: Protons + neutrons.

• Octet Rule: Atoms tend to have 8 electrons in their valence shell.

• Ionic Bond: Transfer of electrons from one atom to another.

• Covalent Bond: Sharing of electrons (polar: unequal sharing; nonpolar: equal sharing).

• Hydrogen Bond: Weak attraction between polar molecules.

Water and pH

• Polarity: Water is polar, allowing hydrogen bonding.

• Hydrophilic: Water-attracting substances.

• Hydrophobic: Water-repelling substances.

• pH Scale: Measures acidity/basicity (0-14); 7 is neutral, below 7 is acidic, above 7 is basic.

pH	Classification
0-6.9	Acid
7	Neutral
7.1-14	Base

Organic Molecules

• Carbohydrates: Monosaccharides, disaccharides, polysaccharides (e.g., glucose, sucrose, glycogen).

• Lipids: Triglycerides, phospholipids, steroids; saturated (no double bonds) vs. unsaturated (double bonds).

• Proteins: Polymers of amino acids; four levels of structure (primary, secondary, tertiary, quaternary).

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

Preferred energy source: Carbohydrates (glucose).

Biochemical Reactions

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers by adding water.

Energy is stored when bonds are formed and released when bonds are broken.

Cell Structure and Function

Cell Organelles

• Nucleus: Contains genetic material (DNA).

• Cytoplasm: Fluid and organelles outside the nucleus.

• Endoplasmic Reticulum (ER): Rough ER (with ribosomes, protein synthesis); Smooth ER (lipid synthesis).

• Golgi Complex: Modifies, sorts, and packages proteins.

• Ribosomes: Sites of protein synthesis.

• Lysosomes: Contain digestive enzymes.

• Cytoskeleton: Provides structural support.

Enzymes

• Usually proteins; speed up reactions by lowering activation energy.

• Substrate: The reactant an enzyme acts upon.

• Activation Energy: Energy required to start a reaction.

Plasma Membrane

• Functions: Selective barrier, communication, cell recognition.

• Selective Permeability: Allows some substances to pass more easily than others; affected by size, charge, solubility.

• Concentration Gradient: Difference in concentration across a membrane.

• Membrane Potential: Voltage difference across the membrane.

• Structure: Phospholipid bilayer with embedded proteins; described by the fluid mosaic model.

Membrane Transport

• Passive Transport: No energy required; includes diffusion and facilitated diffusion.

• Osmosis: Diffusion of water across a membrane.

• Active Transport: Requires energy; includes primary (direct ATP use) and secondary (uses ion gradients) transport.

Solution Type	Effect on Cell
Hypotonic	Cell swells (water enters)
Hypertonic	Cell shrinks (water leaves)
Isotonic	No net change

Cell Division and Genetics

Mitosis vs. Meiosis

• Mitosis: Produces two identical diploid cells for growth/repair.

• Meiosis: Produces four non-identical haploid gametes for reproduction.

Stages of mitosis: Prophase, Metaphase, Anaphase, Telophase.

Interphase: Cell grows, DNA replicates, prepares for division.

DNA and Protein Synthesis

• DNA Structure: Double helix; base pairing (A-T, C-G).

• Semi-conservative Replication: Each new DNA has one old and one new strand.

• Gene: DNA segment coding for a protein.

• Gene Expression: Process by which information from a gene is used to synthesize a functional product.

• Transcription: DNA → mRNA in nucleus.

• Translation: mRNA → protein at ribosome.

• mRNA: Messenger RNA; carries code from DNA.

• tRNA: Transfer RNA; brings amino acids to ribosome.

• rRNA: Ribosomal RNA; part of ribosome structure.

• Codon: Three-base sequence on mRNA.

• Anticodon: Three-base sequence on tRNA, complementary to codon.

Example: DNA: TCG GGG CCC AGA → mRNA: AGC CCC GGG UCU → tRNA: UCG GGG CCC AGA → Amino acids: Ser-Pro-Gly-Ser

Tissues and Integumentary System

Basic Tissue Types

• Epithelial: Covers surfaces, lines cavities.

• Connective: Supports, binds, protects.

• Muscle: Movement.

• Nervous: Communication.

Examples of Tissues

Tissue Type	Location	Function
Simple squamous epithelium	Alveoli of lungs	Diffusion
Simple columnar epithelium	Digestive tract	Absorption; microvilli increase surface area
Stratified squamous epithelium	Skin, mouth	Protection
Pseudostratified ciliated columnar	Trachea	Secretion, movement of mucus
Hyaline cartilage	Joints, nose	Support, flexibility
Elastic cartilage	Ear	Flexibility
Fibrocartilage	Intervertebral discs	Shock absorption
Dense irregular connective	Dermis of skin	Strength in multiple directions

Skin Structure and Function

• Epidermis Layers: Stratum basale (growth), spinosum, granulosum, lucidum (thick skin), corneum (apoptosis occurs in upper layers).

• Melanocytes: Produce melanin; skin color variation due to melanin type/amount and distribution.

Skeletal System

Long Bone Structure

• Diaphysis: Shaft; compact bone.

• Epiphysis: Ends; spongy bone.

• Metaphysis: Growth plate region.

• Medullary Cavity: Contains marrow.

• Periosteum: Outer covering.

Bone Cells and Matrix

• Osteoprogenitor cells: Stem cells.

• Osteoblasts: Build bone matrix.

• Osteocytes: Maintain bone tissue.

• Osteoclasts: Break down bone.

• Matrix: Non-cellular; composed of collagen fibers and mineral salts.

Bone Types and Growth

• Compact Bone: Dense, outer layer.

• Spongy Bone: Porous, inner layer.

• Appositional Growth: Bone thickening.

• Epiphyseal Plate Growth: Bone lengthening.

Bone Repair and Hormones

• Four stages of fracture repair: Hematoma, fibrocartilaginous callus, bony callus, remodeling.

• Parathyroid Hormone (PTH): Increases blood Ca2+; from parathyroid glands.

• Calcitonin: Lowers blood Ca2+; from thyroid gland.

Sex Differences in Skeleton

• Male and female skeletons differ in pelvic structure, skull features, etc. (not rib number).

Protein Synthesis and Mutations

• Proteins are synthesized from amino acids via transcription and translation.

• Mutations in DNA can alter amino acid sequence, potentially resulting in nonfunctional enzymes.

Additional info:

• Some content (e.g., drawings, labeling) is referenced but not provided; students should consult diagrams in their textbook for visual reinforcement.

• For cranial nerves, refer to a table or chart for names, numbers, and functions.