Study Guide: Integumentary, Skeletal, Muscular, and Nervous Systems with General and Special Senses

Integumentary System

Functions of the Integument

The integumentary system, primarily the skin, serves as the body's first line of defense and performs several vital functions:

• Protection: Acts as a barrier against pathogens, chemicals, and physical injuries.

• Thermoregulation: Regulates body temperature through sweat production and blood flow.

• Sensation: Contains sensory receptors for touch, pain, temperature, and pressure.

• Excretion: Removes waste products through sweat.

• Synthesis of Vitamin D: Initiates vitamin D production when exposed to UV light.

Types of Glands

• Sudoriferous (Sweat) Glands: Produce sweat for cooling and excretion. Two types: eccrine (widely distributed, regulate temperature) and apocrine (found in armpits/groin, active after puberty).

• Sebaceous Glands: Secrete sebum (oil) to lubricate skin and hair.

• Ceruminous Glands: Produce earwax in the ear canal.

• Mammary Glands: Specialized for milk production.

Tissues in the Dermis

• Dense Irregular Connective Tissue: Provides strength and elasticity.

• Areolar Connective Tissue: Supports and binds other tissues, found in the papillary layer.

Pigments in the Epidermis

• Melanin: Brown-black pigment produced by melanocytes; protects against UV radiation.

• Carotene: Yellow-orange pigment from diet, accumulates in stratum corneum.

• Hemoglobin: Red pigment in blood, visible through thin skin.

Properties/Locations of Layers of the Skin

• Epidermis: Outermost layer; stratified squamous epithelium; avascular.

• Dermis: Middle layer; contains connective tissue, blood vessels, nerves, glands.

• Hypodermis (Subcutaneous Layer): Deepest; adipose and areolar tissue; insulates and anchors skin.

Skeletal System

Anatomy and Function of Osteons and Their Parts

Osteons (Haversian systems) are the structural units of compact bone.

• Central (Haversian) Canal: Contains blood vessels and nerves.

• Lamellae: Concentric rings of calcified matrix.

• Lacunae: Small spaces housing osteocytes.

• Canaliculi: Tiny channels connecting lacunae for nutrient/waste exchange.

Bone Types

• Long Bones: Longer than wide (e.g., femur).

• Short Bones: Cube-shaped (e.g., carpals).

• Flat Bones: Thin, often curved (e.g., skull, ribs).

• Irregular Bones: Complex shapes (e.g., vertebrae).

• Sesamoid Bones: Embedded in tendons (e.g., patella).

Types of Motion

• Flexion/Extension: Decreasing/increasing angle between bones.

• Abduction/Adduction: Movement away from/toward midline.

• Rotation: Bone turns around its own axis.

• Circumduction: Circular movement combining flexion, extension, abduction, adduction.

Types and Properties of Joints

• Fibrous Joints: Immovable (e.g., sutures in skull).

• Cartilaginous Joints: Slightly movable (e.g., intervertebral discs).

• Synovial Joints: Freely movable; contain synovial fluid (e.g., knee, shoulder).

Functions of the Skeletal System

• Support: Framework for the body.

• Protection: Shields vital organs.

• Movement: Leverage for muscles.

• Mineral Storage: Reservoir for calcium and phosphorus.

• Blood Cell Production: Hematopoiesis in red marrow.

• Triglyceride Storage: In yellow marrow.

Key Features of Male/Female Pelvic Girdles

• Male Pelvis: Narrower, heavier, more vertical; pubic arch angle < 90°.

• Female Pelvis: Wider, lighter, more shallow; pubic arch angle > 90°; adapted for childbirth.

Characteristics/Parts of Long Bones

• Diaphysis: Shaft; compact bone.

• Epiphyses: Ends; spongy bone with red marrow.

• Metaphysis: Region between diaphysis and epiphysis; contains growth plate.

• Medullary Cavity: Central cavity with yellow marrow.

• Periosteum: Outer covering; contains nerves and blood vessels.

Properties of Spongy Bone

• Trabeculae: Lattice-like network; spaces filled with red marrow.

• Lightweight: Reduces bone weight while maintaining strength.

• Location: Found in epiphyses of long bones, interior of flat bones.

Muscular System

Where ACh is Found in Muscles

• Acetylcholine (ACh): Neurotransmitter released at the neuromuscular junction; binds to receptors on muscle fiber to initiate contraction.

Functions, Parts, and Borders of Sarcomeres

• Sarcomere: Functional unit of muscle contraction; extends from one Z line to the next.

• Parts: Z lines (boundaries), M line (center), A band (thick filaments), I band (thin filaments), H zone (thick filaments only).

• Transverse (T) Tubules: Invaginations of sarcolemma; transmit action potentials.

• Myofibrils: Bundles of actin and myosin filaments within muscle fibers.

Parts of Whole Muscles

• Muscle Fiber: Single muscle cell.

• Fascicle: Bundle of muscle fibers.

• Epimysium: Surrounds entire muscle.

• Perimysium: Surrounds fascicles.

• Endomysium: Surrounds individual muscle fibers.

Muscle Functions

• Movement: Locomotion and manipulation.

• Posture: Maintains body position.

• Stabilization: Stabilizes joints.

• Heat Production: Generates heat during contraction.

Why Skeletal Muscles Appear Striated

• Striations: Due to the regular arrangement of actin and myosin filaments in sarcomeres.

Central Nervous System (CNS)

Functions of Neurons and Their Parts

• Neurons: Conduct electrical impulses.

• Dendrites: Receive signals.

• Cell Body (Soma): Contains nucleus and organelles.

• Axon: Transmits impulses away from cell body.

• Axon Terminals: Release neurotransmitters.

What Comprises CNS

• Brain

• Spinal Cord

Efferent vs Afferent Divisions of the Nervous System

• Afferent (Sensory) Division: Carries sensory information to CNS.

• Efferent (Motor) Division: Carries commands from CNS to effectors (muscles/glands).

Brain Anatomy and Functions of Different Brain Divisions

• Cerebrum: Higher brain functions (thought, memory, voluntary movement).

• Cerebellum: Coordination and balance.

• Diencephalon: Includes thalamus (sensory relay) and hypothalamus (homeostasis).

• Brainstem: Midbrain, pons, medulla oblongata; controls vital functions (breathing, heart rate).

Gray vs White Matter in Spinal Cord and Brain

• Gray Matter: Neuron cell bodies, dendrites, unmyelinated axons; processing and integration.

• White Matter: Myelinated axons; transmits signals between regions.

Meninges in the Spinal Cord and Brain

• Dura Mater: Tough outer layer.

• Arachnoid Mater: Middle, web-like layer.

• Pia Mater: Delicate inner layer, adheres to CNS surface.

Peripheral Nervous System (PNS)

Postganglionic Fibers of the Parasympathetic Division

• Parasympathetic Postganglionic Fibers: Release acetylcholine; target organs for 'rest and digest' responses.

Sympathetic vs Parasympathetic Responses

Sympathetic	Parasympathetic
"Fight or flight"	"Rest and digest"
Increases heart rate	Decreases heart rate
Dilates pupils	Constricts pupils
Inhibits digestion	Stimulates digestion

Ascending vs Descending Pathways

• Ascending Pathways: Sensory tracts carrying information to the brain.

• Descending Pathways: Motor tracts carrying commands from the brain to effectors.

Components and Correct Order of a Reflex Arc

1. Receptor

2. Sensory (Afferent) Neuron

3. Integration Center (CNS)

4. Motor (Efferent) Neuron

5. Effector

General and Special Senses

Receptor Types

• Mechanoreceptors: Detect touch, pressure, vibration.

• Thermoreceptors: Detect temperature changes.

• Photoreceptors: Detect light (in eyes).

• Chemoreceptors: Detect chemicals (taste, smell).

• Nociceptors: Detect pain.

Eye Structures/Functions

• Cornea: Transparent, refracts light.

• Iris: Controls pupil size.

• Lens: Focuses light on retina.

• Retina: Contains photoreceptors (rods and cones).

• Optic Nerve: Transmits visual information to brain.

Layers of the Eye

• Fibrous Tunic: Sclera and cornea.

• Vascular Tunic (Uvea): Choroid, ciliary body, iris.

• Nervous Tunic: Retina.

Properties of Eye Humors

• Aqueous Humor: Clear fluid in anterior chamber; nourishes lens and cornea.

• Vitreous Humor: Gel-like substance in posterior chamber; maintains eye shape.

Types of Eye Cones

• S-cones: Sensitive to short wavelengths (blue).

• M-cones: Sensitive to medium wavelengths (green).

• L-cones: Sensitive to long wavelengths (red).

Properties of Eye Cavities

• Anterior Cavity: Contains aqueous humor; between cornea and lens.

• Posterior Cavity: Contains vitreous humor; between lens and retina.

Ear Structures/Functions

• Outer Ear: Auricle (pinna), external auditory canal; collects sound.

• Middle Ear: Tympanic membrane, ossicles (malleus, incus, stapes); transmits vibrations.

• Inner Ear: Cochlea (hearing), vestibule and semicircular canals (balance).

Ear Passages

• External Auditory Canal: Leads sound to tympanic membrane.

• Eustachian Tube: Equalizes pressure between middle ear and throat.

Organ of Corti

• Organ of Corti: Located in cochlea; contains hair cells that transduce sound vibrations into nerve impulses.