Unit B: Tissues & Integumentary System Study Guide

Importance of epithelial tissue

Covers body surfaces and lines body cavities, protecting, absorbing, and filtering substances.

Importance of connective tissue

Supports, protects, insulates, transports, and binds other tissues together.

Importance of muscle tissue

Made of tightly packed cells that contract to produce movement.

Importance of nervous tissue

Controls regulation and communication by converting stimuli into nerve impulses.

Simple vs. stratified epithelia

Simple epithelium has one cell layer; stratified epithelium has multiple cell layers.

Squamous epithelium characteristics

Flat, thin cells specialized for diffusion.

Cuboidal epithelium characteristics

Cube-shaped cells specialized for secretion and absorption.

Columnar epithelium characteristics

Tall, rectangular cells providing maximum surface area for absorption.

Function of exocrine glands

Secrete products externally, usually through a duct onto a body surface.

Function of endocrine glands

Secrete hormones internally directly into the bloodstream.

Merocrine gland secretion method

Secretes substances through exocytosis while keeping the cell intact.

Apocrine gland secretion method

A portion of the cell pinches off with the secretion, then repairs itself.

Holocrine gland secretion method

Cells rupture entirely, dying and becoming the secreted product.

Function of connective tissue proper

Insulates and protects organs while storing energy as fat.

Function of bone (osseous) tissue

Supports and protects organs and stores minerals like calcium and phosphate.

Function of cartilage

Supports, cushions, and protects organs by resisting compression.

Function of blood tissue

Transports oxygen, carbon dioxide, nutrients, wastes, and hormones throughout the body.

Pseudostratified epithelial tissue structure

Single cell layer of varying heights creating a false appearance of multiple layers.

Skeletal muscle characteristics and role

Attached to bones, striated, and contracts voluntarily to produce movement.

Smooth muscle characteristics and role

Non-striated and involuntary; found in organ walls controlling internal movements.

Cardiac muscle characteristics and role

Striated, branched, and involuntary; found in the heart to pump blood.

Role of neurons in nervous tissue

Convert stimuli into nerve impulses and transmit them; unable to regenerate.

Role of neuroglia in nervous tissue

Support and protect neurons without generating impulses; able to regenerate.

Epithelial classification by layer count

Classified as simple (one layer), stratified (multiple layers), or pseudostratified.

Epithelial classification by cell shape

Classified as squamous (flat), cuboidal (cube-shaped), or columnar (tall).

Apocrine

Glandular secretion where the cell tip pinches off with the product (e.g., mammary glands).

Chondrocyte

A cartilage cell; maintains non-vascular cartilage that resists compression.

Collagen fiber

Strong protein fiber in connective tissue providing high tensile strength.

Elastic fiber

Stretchy, flexible connective tissue fiber providing cushioning and stretch.

Ground substance

Unstructured material surrounding cells and fibers in connective tissue.

Histology

Microscopic study of tissues, including their structure and function.

Holocrine

Glandular secretion where entire cells rupture to release products (e.g., sebaceous glands).

Hyaline

Most common, glassy cartilage type; cushions joints, trachea, and nose.

Merocrine

Glandular secretion via exocytosis leaving the cell undamaged (e.g., sweat glands).

Neuroglia

Glial cells that support, protect, and repair nervous tissue.

Neuron

Nerve cell that converts stimuli to electrical impulses for communication.

Pseudostratified

Epithelium that appears layered due to varying cell heights but is single-layered.

Reticular fiber

Fine connective tissue fiber forming supportive mesh frameworks for soft organs.

Tissue

Group of similar cells working together to perform a specific function.

Transitional

Stretchable epithelial tissue lining urinary organs that changes shape under pressure.

Main function of the integumentary system

Protection; formed by skin, glands, hair, and nails.

Integumentary role in vitamin D synthesis

Synthesizes vitamin D in response to sunlight, aiding calcium absorption.

Integumentary role in thermoregulation

Regulates temperature via blood vessel dilation/constriction and sweat evaporation.

Integumentary role in sensation

Detects environmental stimuli through sensory nerve receptors.

Integumentary role in excretion

Excretes small amounts of nitrogenous waste and salts through sweat.

Additional integumentary system role

Helps maintain fluid balance and prevent hydration loss.

Epidermis characteristics

Avascular epithelial tissue forming a protective, waterproof outer barrier.

Dermis characteristics

Vascularized dense connective tissue providing structural strength, flexibility, and sensation.

Role of keratinocytes

Produce keratin to construct a durable, waterproof epidermal barrier.

Role of melanocytes

Produce melanin pigment to shield cell nuclei from UV radiation.

Role of dendritic (Langerhans) cells

Ingest foreign invaders and initiate immune responses in skin.

Role of tactile epithelial (Merkel) cells

Combine with nerve endings at the epidermal-dermal junction for light touch sensing.

Role of stem cells in the epidermis

Located in stratum basale to continually generate new keratinocytes.

Stratum basale

Deepest epidermal layer; single row of stem cells, melanocytes, and Merkel cells.

Stratum spinosum

Prickly epidermal layer with filaments resisting tension; contains dendritic cells.

Stratum granulosum

Granular epidermal layer where cells fill with keratin and flatten.

Stratum lucidum

Clear layer of dead keratinocytes present only in thick skin.

Stratum corneum

Outermost epidermal layer of dead cells preventing water loss and abrasion.

Papillary dermis

Superficial dermal layer of areolar tissue forming papillae with capillary loops and receptors.

Reticular dermis

Deep dermal layer of dense irregular connective tissue providing strength and elasticity.

Composition of the hypodermis

Subcutaneous layer primarily composed of adipose tissue.

Functions of the hypodermis

Insulates, stores fat energy, absorbs shocks, and anchors skin to muscle.

Nail root

Proximal portion of the nail embedded deep within the skin.

Nail plate / body

Visible attached, hardened portion of the nail.

Free edge of a nail

Distal part of the nail extending past the fingertip.

Nail bed

Layer of epidermis beneath the nail plate.

Nail matrix

Thickened proximal area responsible for continuous nail growth.

Eccrine sweat gland location & purpose

Widespread (dense on palms/soles); secretes watery sweat for cooling and protection.

Apocrine sweat gland location & purpose

Axillary and anogenital regions; secretes fatty sweat active from puberty into hair follicles.

Sebaceous gland location & purpose

All skin except palms/soles; secretes oily sebum into hair follicles to lubricate skin.

Apocrine gland

Large sweat gland in armpits and groin active from puberty.

Arrector pili

Smooth muscle attached to hair follicles that pulls hairs upright when contracted.

Basal layer concept

Refers to the deepest stratum basale layer where active mitosis occurs.

Dermal papillae

Fingerlike projections of the dermis into the epidermis containing capillaries and tactile receptors.

Eccrine gland

Abundant merocrine sweat gland active from birth that regulates body temperature.

Hair follicles

Tubular invaginations of the epidermis from which hair develops.

Keratin

Fibrous protective protein that toughens skin, hair, and nails.

Keratinocytes

Primary epidermal cells that produce keratin for physical protection.

Lunula

Crescent-shaped white area at the base of the nail covering the matrix.

Melanin

Pigment absorbing harmful UV light produced by melanocytes.

Melanocytes

Cells in the stratum basale that synthesize melanin pigment.

Sebaceous gland

Exocrine gland producing sebum to soften hair and reduce epidermal water loss.

Sudoriferous gland

General term for sweat glands, including eccrine and apocrine types.