Human Anatomy and Physiology Lecture Review
Hierarchical Organization of the Human Body
The human body is organized into a hierarchical structure ranging from the smallest chemical components up to the complete organism.
Chemical Level: This level includes atoms and molecules. Examples provided include water and glucose.
Cellular Level: Cells are the smallest functional units of life. An example is the muscle cell.
Tissue Level: This consists of groups of similar cells working together to perform a specific function. An example is muscle tissue.
Organ Level: At this level, different types of tissues work together. An example is the heart.
System Level: This involves multiple organs working together to achieve a shared purpose. An example is the cardiovascular system.
Organism Level: The highest level, representing the entire human body as a unified whole.
The 11 Organ Systems
Integumentary System: Functions in protection and temperature regulation. Key components include the skin, hair, and nails.
Skeletal System: Provides support, protection for internal organs, and is the site of blood cell production.
Muscular System: Responsible for movement and the production of heat.
Nervous System: Facilitates rapid communication and control throughout the body.
Endocrine System: Responsible for hormone regulation and long-term control of body processes.
Cardiovascular System: Transports blood, nutrients, and gases (oxygen and carbon dioxide).
Lymphatic System: Functions in immune defense and maintaining fluid balance.
Respiratory System: Facilitates gas exchange (specifically and ).
Digestive System: Breaks down food and absorbs necessary nutrients.
Urinary System: Removes waste products and regulates fluid levels.
Reproductive System: Functions to produce offspring.
Cellular Components and Membrane Structure
Cell Membrane Structure: The membrane is characterized as a phospholipid bilayer.
Hydrophilic heads: These face outward toward the aqueous environment.
Hydrophobic tails: These face inward, away from water.
Additional components include proteins, cholesterol, and carbohydrates.
Membrane Function: The membrane is selectively permeable, meaning it controls what enters and exits the cell.
Small and nonpolar molecules can pass through easily.
Proteins regulate the movement of other substances through channels, carriers, and pumps.
Cytoplasm: This is the gel-like fluid inside the cell that contains organelles and supports various cellular processes.
Organelles and Their Functions
Ribosomes: The site of protein synthesis.
Endoplasmic Reticulum (ER):
Rough ER: Associated with protein synthesis and modification.
Smooth ER: Involved in lipid synthesis and detoxification.
Golgi Complex: Responsible for modifying and packaging proteins for transport.
Lysosomes: Responsible for digestion and the removal of waste.
Mitochondria: The "powerhouse" of the cell, responsible for the production of ATP (energy).
Cell Transport and the Nucleus
Passive Transport: Does not require ATP (energy).
Diffusion: Movement of particles from high to low concentration.
Osmosis: The movement of water across a semipermeable membrane.
Facilitated Diffusion: Movement aided by transport proteins.
Active Transport: Requires ATP (energy) to move substances against their concentration gradient, often via protein pumps.
The Nucleus: This is the control center of the cell.
Components: Includes the nuclear membrane, nucleolus, and chromatin.
Function: It stores DNA and controls all cellular activities.
Comparison of Cell Types and Division
Mitosis vs. Meiosis:
Mitosis: Results in identical diploid cells. Used for growth and tissue repair.
Meiosis: Results in non-identical haploid cells. Used for gamete production.
Somatic vs. Germ Cells:
Somatic Cells: General body cells that are diploid. Examples include:
Muscle cells: Function in contraction.
Neurons: Function in communication.
Skin cells: Function in protection.
Germ Cells: Reproductive cells that are haploid. There are two types: Sperm and Egg (ovum).
The Four Main Tissue Types
Epithelial Tissue: Covers body surfaces and lines cavities. Primary functions include protection, absorption, and secretion.
Connective Tissue: Provides support and connects different parts of the body. Types include bone, cartilage, blood, and fat.
Muscle Tissue: Specialized for contraction and movement.
Skeletal: Controls voluntary movement.
Smooth: Found in internal organs.
Cardiac: Found specifically in the heart.
Nervous Tissue: Specialized for communication.
Neurons: Cells that transmit electrical signals.
Neuroglia: Cells that support and protect neurons.
Anatomical Terminology and Body Cavities
Anatomical Position: A standard position where the subject stands upright, facing forward, with arms at the sides and palms facing forward.
Axial vs. Appendicular:
Axial: Includes the head, neck, and trunk.
Appendicular: Includes the limbs.
Directional Terms:
Anterior: The front.
Posterior: The back.
Superior: Above.
Inferior: Below.
Medial: Toward the midline.
Lateral: Away from the midline.
Proximal: Closer to the origin or point of attachment.
Distal: Farther from the origin.
Superficial: Near the surface.
Deep: Farther inside the body.
Anatomical Planes:
Sagittal: Divides the body into left and right.
Frontal: Divides the body into front and back.
Transverse: Divides the body into top and bottom.
Body Cavities:
Dorsal Cavity: Contains the cranial and spinal cavities.
Ventral Cavity: Contains the thoracic and abdominopelvic cavities.
Abdominal Quadrants: Divided into RUQ, LUQ, RLQ, and LLQ, primarily used for locating internal organs.
Homeostasis and Feedback Systems
Homeostasis: The process of maintaining a stable internal balance (e.g., body temperature regulation).
Key Terms:
Set point: The ideal value for a physiological state.
Range: The acceptable variation around the set point.
Normal limits: The boundaries between balance and imbalance.
Feedback System Components:
Stimulus: The change being detected.
Receptor: Detects the change.
Control Center: Processes the information.
Effector: Executes the response.
Response: The result of the effector's action.
Types of Feedback:
Negative Feedback: Opposes the initial change to return to the set point (e.g., temperature regulation).
Positive Feedback: Amplifies the initial change (e.g., childbirth).
Homeostatic Imbalance: A disruption in balance that can lead to disease.
The Integumentary System: Skin Layers and Anatomy
Major Layers of the Skin:
Major Layers of the Skin:
Epidermis: The outermost layer. It is avascular (lacks blood vessels), comprised primarily of keratinized epithelial cells, which undergo rapid turnover and act as a waterproof barrier. The epidermis contains several types of cells:
Keratinocytes: Produce keratin for strength and waterproofing.
Melanocytes: Produce melanin, which gives skin its color and provides protection against UV radiation.
Langerhans cells: Function as immune defenders against pathogens.
Merkel cells: Act as touch receptors that contribute to the sensation of light touch.
Dermis: The inner layer, consisting of dense connective tissue that provides strength and elasticity. This layer contains:
Blood Vessels: Supply nutrients and oxygen, aid in thermoregulation.
Nerves: Sensory receptors for pressure, pain, temperature.
Glands:
Sebaceous glands: Secrete oils to lubricate the skin and hair.
Sweat glands: Aid in thermoregulation through the secretion of sweat.
Hair follicles: Sites from which hair grows, contributing to thermoregulation and protection.
Hypodermis (Subcutaneous Layer): Located beneath the dermis; though not technically part of the skin, it provides support and insulation. It contains:
Loose connective tissue and fat: Functions as energy storage, cushioning, and insulation.
Major blood vessels and nerves: Contribute to thermoregulation and sensory pathway
Skin Color Contribution: Influenced by Melanin (primary), Carotene, and Hemoglobin (blood flow).
Primary Functions of Skin:
Protection: Barrier against pathogens, UV radiation, and injury.
Thermoregulation: Controlled through sweating and changes in blood flow.
Sensory: Detects touch, pain, and temperature through receptors.
Secretion: Production of sweat and oils.
Vitamin D Synthesis: Exposure to UV light triggers production.
Epidermal Stratification and Cell Types
Epidermal Cell Types:
Keratinocytes: Most common; produce keratin.
Melanocytes: Produce melanin.
Langerhans cells: Provide immune defense.
Merkel cells: Act as touch receptors.
Strata of the Epidermis (Deep to Superficial):
Stratum basale: Site of active cell division.
Stratum spinosum.
Stratum granulosum.
Stratum lucidum: Found only in thick skin (e.g., palms, soles).
Stratum corneum: Layers of dead, keratinized cells.
Skin Structures, Glands, and Thermoregulation
Gland Functions:
Sebaceous glands: Secrete oil to lubricate skin and hair.
Sweat glands: Assist in temperature regulation.
Ceruminous glands: Produce earwax.
Thermoregulation Response: Arrector pili muscles contract to make hair stand up (goosebumps) in response to cold.
Sensory Receptors: Detect touch, pressure, pain, temperature, and vibration.
Wound Healing, Burns, and Skin Disorders
Wound Types:
Epidermal: Surface-level only; heals quickly without scarring.
Deep: Extends into the dermis; results in bleeding and potential scarring.
Phases of Deep Wound Healing:
Inflammation
Proliferation (new tissue formation)
Remodeling (tissue strengthening)
Burn Severity:
1st Degree: Affects the epidermis only.
2nd Degree: Affects the epidermis and dermis; characterized by blisters.
3rd Degree: Full-thickness damage; severe tissue destruction.
Skin Cancer: Caused by UV radiation damaging DNA.
Basal cell carcinoma: Most common, least severe.
Squamous cell carcinoma: Moderate risk.
Melanoma: Most dangerous; spreads quickly.
ABCDE Mnemonic: A = Asymmetry, B = Border irregular, C = Color variation, D = Diameter > 6\,mm, E = Evolving.
Other Disorders:
Eczema: Inflammatory condition causing dry, itchy skin.
Acne: Caused by blocked pores and bacteria leading to inflammation.
Aging and Effects on Homeostasis
Skin: Becomes thinner and loses elasticity.
Bones: Experience decreased density.
Joints: Increased stiffness.
Muscles: Loss of mass (atrophy).
Cells: Slower rate of division.
Systemic effects: Reduced healing ability and less efficient feedback loops (slower responses).
Skeletal System: Bone Cells and Tissues
Types of Bone Cells:
Osteogenic (Osteoprogenitor) Cells: Stem cells found in the periosteum and endosteum; they differentiate into osteoblasts.
Osteoblasts: Cells that build bone by secreting the bone matrix (collagen and minerals).
Osteocytes: Mature cells that maintain bone tissue; they reside in lacunae and communicate via canaliculi.
Osteoclasts: Large, multinucleated cells that resorb (break down) bone for remodeling and calcium balance.
Types of Bone Tissue:
Compact Bone: Strong, dense outer layer organized into osteons (Haversian systems).
Spongy Bone (Cancellous): Porous, trabecular structure containing red marrow for blood cell production.
Spongy Bone Organization and Cartilage
Trabeculae: Lattice-like network providing support.
Lacunae: Small spaces that house osteocytes.
Canaliculi: Fine channels connecting lacunae for nutrient and waste exchange.
Lamellae: Concentric layers of bone matrix.
Cartilage Types:
Hyaline: Smooth and flexible; found in joints, nose, and trachea.
Fibrocartilage: Tough and absorbs shock; found in intervertebral discs.
Elastic: Highly flexible; found in the ear.
Anatomy and Classification of Bones
Long Bone Structure:
Diaphysis: The shaft (mainly compact bone).
Epiphysis: The ends of the bone (mainly spongy bone).
Metaphysis: Region between diaphysis and epiphysis.
Periosteum: Outer fibrous covering; critical for growth and repair.
Endosteum: Inner lining containing osteogenic cells.
Medullary Cavity: The central space in the diaphysis.
Bone Marrow:
Red Marrow: Site of RBC, WBC, and platelet production.
Yellow Marrow: Site of fat storage; can convert to red marrow if necessary.
Bone Shapes:
Long: Length is greater than width (e.g., femur).
Short: Cube-shaped (e.g., carpals).
Flat: Thin and protective (e.g., skull, sternum).
Irregular: Complex shapes (e.g., vertebrae).
Sesamoid: Embedded in tendons (e.g., patella).
Axial and Appendicular Skeleton Details
Skull Bones:
Cranial: Frontal, Parietal, Temporal, Occipital, Sphenoid, Ethmoid.
Facial: Maxilla, Mandible, Zygomatic (cheeks), Nasal, Lacrimal (tear-drainage support).
Sutures: Immovable joints that articulate skull bones.
Sinuses: (Frontal, Maxillary, Ethmoid, Sphenoid) lighten the skull, warm air, and enhance voice resonance.
Vertebral Column Regions:
Cervical:
Thoracic:
Lumbar:
Sacrum and Coccyx
Thoracic Cage: Includes the sternum, ribs, and thoracic vertebrae; protects the heart and lungs.
Limbs:
Upper: Pectoral girdle (clavicle, scapula), arm (humerus, radius, ulna), and hand (carpals, metacarpals, phalanges).
Lower: Pelvic girdle (ilium, ischium, pubis), leg (femur, patella, tibia, fibula), and foot (tarsals, metatarsals, phalanges).
Joint Classification and Movement
Structural Classification:
Fibrous: No movement (e.g., skull sutures).
Cartilaginous: Slight movement (e.g., spine).
Synovial: Free movement with a joint cavity (e.g., knee).
Functional Classification:
Synarthrosis: Immobile.
Amphiarthrosis: Slightly movable.
Diarthrosis: Freely movable.
Types of Range of Motion (ROM): Flexion, Extension, Abduction, Adduction, and Rotation.
Muscular System: Types and Tissue Organization
Muscle Types:
Skeletal: Voluntary, striated, attached to bone.
Cardiac: Involuntary, striated, contains intercalated discs.
Smooth: Involuntary, non-striated, found in organs.
Connective Tissue Wrappings:
Epimysium: Surrounds the entire muscle.
Perimysium: Surrounds fascicles (bundles of fibers).
Endomysium: Surrounds individual muscle fibers.
Fascicle Arrangements: Parallel (strap-like), Fusiform (spindle-shaped), Circular (sphincters), and Pennate (feather-like: uni, bi, or multi).
Muscle Nomenclature and Mechanics
Nomenclature Basis:
Orientation: Rectus (straight), Oblique (diagonal), Transverse (horizontal).
Shape: Deltoid (triangle), Trapezius (trapezoid), Rhomboid (diamond), Serratus (saw-like), Gracilis (slender), Platys (flat), Quadrate (square), Piriformis (pear-shaped).
Action: Flexor (decreases angle), Extensor (increases angle), Abductor (away from midline), Adductor (toward midline).
Muscle Mechanics: Muscles work as lever systems where bones act as bars and joints act as pivots.
Agonist: The primary mover.
Antagonist: Opposes the agonist.
Microscopic Anatomy and Muscle Contraction
Sarcomere Components: The functional unit of contraction.
Actin: Thin filaments.
Myosin: Thick filaments; pulls actin to shorten the sarcomere.
Regulatory Proteins: Tropomyosin (blocks binding sites) and Troponin (moves tropomyosin when binds).
Contraction Steps:
Nerve signal arrives at the neuromuscular junction.
Acetylcholine (ACh) is released and binds to receptors.
Myosin binds to actin (cross-bridge formation).
Power stroke occurs (pulling actin).
ATP facilitates detachment and reset of the myosin head.
Exercise vs. Aging: Exercise leads to hypertrophy and endurance; aging leads to atrophy and slower repair.
Regional Musculature
Head/Face: Frontalis (eyebrows), Orbicularis oculi (eyes), Orbicularis oris (lips), Zygomaticus (smiling), Buccinator (cheeks), Masseter (chewing), Temporalis (mandible movement).
Neck/Back: Sternocleidomastoid (rotation/flexion), Trapezius (shoulder/neck), Erector spinae (spine extension), Latissimus dorsi (arm movement).
Trunk: Rectus abdominis (spine flexion), External/Internal obliques (rotation), Transversus abdominis (compression), Diaphragm and Intercostals (breathing).
Upper Limbs: Pectoralis major, Deltoid (abduction), Biceps brachii (flexion), Triceps brachii (extension), Rotator Cuff (SITS: Supraspinatus, Infraspinatus, Teres minor, Subscapularis).
Lower Limbs: Gluteus maximus (extension) and medius (abduction); Quadriceps group (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) for knee extension; Hamstrings (biceps femoris, semitendinosus, semimembranosus) for knee flexion; Tibialis anterior (dorsiflexion); Gastrocnemius and Soleus (plantar flexion).
Nervous System: Organization and Tissue
Central Nervous System (CNS): Includes the Brain and Spinal cord.
Peripheral Nervous System (PNS):
Somatic: Voluntary control of skeletal muscles.
Autonomic: Involuntary control (Sympathetic: fight/flight; Parasympathetic: rest/digest).
Enteric: Controls digestion in the GI tract.
Neuron Anatomy: Cell body (soma), Dendrites (receive signals), Axon (sends signals), Myelin sheath (insulation for speed).
Glial Cells (Support Cells):
Astrocytes: Blood-brain barrier support.
Oligodendrocytes: Myelin in CNS.
Schwann Cells: Myelin in PNS.
Microglia: Immune defense.
Ependymal cells: Produce cerebrospinal fluid (CSF).
Cranial Nerves: pairs; sensory and motor control of the head.
Brain Anatomy and Physiology
Four Main Parts: Cerebrum (thinking, voluntary movement), Cerebellum (balance), Brainstem (survival), Diencephalon (hormone/sensory relay).
Gray vs. White Matter: Gray matter houses cell bodies (processing); white matter houses myelinated axons (communication).
Brain Structures:
Thalamus: Sensory relay station.
Hypothalamus: Homeostasis and endocrine control.
Pineal Gland: Melatonin production/sleep cycle.
Pituitary Gland: Master endocrine controller.
Brainstem components: Midbrain, Pons (breathing), Medulla oblongata (heart rate/blood pressure).
Protection: Meninges (Dura mater, Arachnoid mater, Pia mater) and the Blood-Brain Barrier.
Cerebrospinal Fluid (CSF): Cushions the brain and circulates nutrients; produced in ventricles.
Spinal Cord and Action Potentials
Spinal Cord Structure: Inner butterfly-shaped gray matter and outer white matter tracts (ascending/descending).
Plexuses: Cervical (neck), Brachial (arms), Lumbar (lower body), Sacral (legs/pelvis).
Action Potentials: An all-or-none electrical signal.
Resting Potential: Approximately .
Depolarization: flows in (inside becomes more positive).
Repolarization: flows out (inside becomes more negative).
Propagation: Saltatory conduction occurs in myelinated axons, making it much faster.
Synapses, Reflexes, and Senses
Synapses: Small gaps where chemicals (neurotransmitters) are released to pass signals.
Reflex Arc: Stimulus Receptor Sensory Neuron CNS Motor Neuron Response.
Types of Reflexes: Stretch reflex, Flexor (withdrawal), and Extensor (balance).
Special Senses:
Olfaction: Smell via olfactory receptors.
Gustation: Taste (Sweet, Sour, Salty, Bitter, Umami).
Vision: Light enters the cornea, intensity is controlled by the iris, and photoreceptors (rods for low light, cones for color) in the retina process images.
Hearing/Balance: The inner ear converts sound to signals; the vestibular system maintains balance.
Endocrine System: Glands and Mechanisms
Endocrine vs. Exocrine:
Endocrine: Ductless; releases hormones directly into the bloodstream.
Exocrine: Uses ducts; secretes onto surfaces or into cavities.
Hypothalamic-Pituitary Axis:
Hypothalamus: Links nervous and endocrine systems; produces ADH and Oxytocin (stored in the posterior pituitary).
Anterior Pituitary: Produces TSH, ACTH, Growth Hormone (GH), Prolactin, FSH, and LH.
Thyroid and Parathyroid:
Thyroid: Produces and for metabolism and Calcitonin to lower blood calcium.
Parathyroid: Produces PTH to raise blood calcium.
Adrenal Glands: Cortex produces cortisol (stress) and aldosterone (water balance); Medulla produces epinephrine/norepinephrine (fight/flight).
Pancreas: Islets of Langerhans produce Insulin (lowers glucose) and Glucagon (raises glucose).
Gonads: Testes (testosterone) and Ovaries (estrogen/progesterone).
Stress Response and Aging of Systems
Stages of Stress Response:
Alarm (fight or flight via epinephrine).
Resistance (sustained via cortisol).
Exhaustion.
Aging Trends: Decreased hormone production, slower response times, and reduced ability to regulate homeostatic set points.
Questions & Discussion
Which hip bone holds the most body weight when sitting?
Answer: Ischium.
Which muscle of the thigh is part of the hamstring?
Answer: Biceps femoris, semitendinosus, or semimembranosus.
What structure holds/contains the pupil?
Answer: Iris.
What causes potassium () gates to open in a cell?
Answer: Depolarization of the membrane (voltage change).
What releases melatonin or controls the sleep cycle?
Answer: Pineal gland.
What process allows water to move across a semipermeable membrane?
Answer: Osmosis.
What is the movement called if it is against the concentration gradient?
Answer: Active transport (requires ATP).
Which bone provides support while also allowing flexibility/movement?
Answer: Vertebrae.