All Unit 2 Definitions
Tissues: Groups of similar cells that act together to perform a particular physiological function.
Polyps: Abnormal growths in the local tissue.
Morula: A ball of undifferentiated stem cells occurring around day 3 to 5 of development.
Totipotent: Stem cells having the ability to differentiate into any future embryonic cells.
Differentiate: Become more specialized and change into specific cells, tissues, or organs.
Potency: The ability of stem cells to differentiate into specialized cells.
Blastocyst: A hollow ball of cells that occurs in the developing embryo.
Pluripotent: Stem cells that can become any cell type or structure in the developed body.
Endoderm: One of the three germinal layers that develops into the gut.
Mesoderm: One of the three germinal layers which develops into the muscles, connective tissue, bones, and some organs.
Ectoderm: One of the three germinal layers which develops into the skin and nervous system.
Stem Cells: Cells with the potential to develop into many different types of cells in the body.
Multipotent: Stem cells that are capable of dividing and becoming multiple cell types within a tissue or organ.
Oligopotency: Stem cells that are capable of dividing and becoming very few cell types.
Unipotency: Ability of the cell to only become one cell type.
Adult stem cells: Undifferentiated cells which exist in differentiated tissues of the adult.
Embryonic Stem Cells: Found in the germinal layers.
Hypertrophy: Enlargement of an existing cell.
Adipocytes: Fat cells.
Hyperplasia: Increase in the number of cells.
Neoplasms: Benign or malignant tumors.
Metaplasia: Tissues changing from one type of tissue into another.
Degenerate: Change from a normally active state into a less functionally active state.
Atrophy: A decrease in the amount of tissue or cell size.
Necrosis: The death of cells in an organ or tissue.
Apoptosis: Programmed cell death.
Epithelial tissue: Makes up most glands, is found on all external body surfaces, and lines the internal surface of organs and body cavities.
Connective tissue: Expansive throughout the body and serves as the “connection point” that binds, anchors, and supports the various cells, tissues, and organs of the body.
Nervous tissue: Controls various functions and activities in the body; it is excitable (responds to stimuli) and communicates control throughout the body with chemical and electrical signals.
Muscular tissue: Excitable, but it responds to stimuli by contracting and is responsible for different types of movement in our bodies.
Epithelial tissue (the epithelium): Found on the external surface of the body and lining the internal surfaces of organs, body cavities, and glands.
Lumen: A hollow space, or the external surface of the body.
Covering + Lining Epithelia: Found on external and internal surfaces of the body.
Glandular Epithelia: Secretory tissues in our glands.
Cell Polarity: The sides of the cells are different and specific.
Apical Surface: The upper, free surface that is facing the lumen or hollow space.
Lateral Surface: Faces adjacent cells and contains cellular junctions (e.g., tight junctions, desmosomes, and gap junctions).
Basal Surface: The lower surface of the epithelium attached to/supported by the basement membrane.
Basement Membrane: A thin, noncellular, extracellular matrix that separates epithelial tissue from the underlying connective tissue.
Hemidesmosomes: Anchoring proteins that serve as “bolts” and attach epithelial tissue to the basement membrane.
Basal Lamina: The more superior portion of the basement membrane composed of a non-cellular matrix of glycoproteins and collagen fibers secreted by the epithelial tissue.
Reticular Lamina: A noncellular matrix of glycoproteins secreted by the connective tissue layer.
Glands: Uni- or multicellular organs made of epithelial cells that specialize in synthesizing and secreting chemicals.
Ducts: Tubes or passageways in exocrine glands through which secreted substances pass.
Exocrine Glands: Epithelial tissue that secretes its substances into ducts, leading to a surface.
Endocrine Glands: Epithelial tissue that secretes hormones directly into the blood.
Hormones: Chemical messengers of the endocrine system.
Unicellular Exocrine Gland: Made of single secretory cells and diffusely spread out within an organ.
Goblet Cells: Unicellular exocrine glands that release mucus onto the surface of epithelial tissue.
Multicellular Exocrine Gland: Glands that secrete their contents into a duct of varying degrees of structural complexity.
Glandular Portion: The cellular part of the gland that makes and secretes substances.
Tubular Glands: Glands that maintain the same straw-like shape throughout their entire length.
Acinar Glands: Glands that expand into sac-like swellings at the deep end.
Tubuloacinar Glands: Glands that combine characteristics of tubular and acinar glands.
Ductal Portion: The portion of the gland that receives secretions from glandular cells.
Simple Duct: An unbranched duct.
Compound Duct: A branched duct.
Merocrine Secretions: Secretions that are exocytosed without harming the cell.
Apocrine Secretions: Secretions where the apical portion of the cell is pinched off.
Holocrine Secretions: Secretions where the entire cell ruptures and is destroyed in the process.
Connective Tissue: Functions to offer connection, binding and support, protection, insulation, and transportation.
Mesenchyme: A loosely organized, mainly mesodermal embryonic tissue that develops into connective and skeletal tissues.
Suffix “cyte”: Refers to a type of mature cell.
Suffix “blast”: Refers to cells that are young, mitotically active, and secretory.
Fibroblasts: Immature cells that make and secrete fibers in some types of connective tissue.
Fibrocytes: Mature cells that make and secrete fibers in some types of connective tissue.
Chondroblasts: Immature cartilage cells that make the extracellular matrix of cartilage until the end of adolescence.
Chondrocytes: Mature cartilage cells that maintain the extracellular matrix of cartilage.
Osteoblasts: Immature bone cells that secrete the extracellular matrix of bone.
Osteocytes: Mature bone cells that maintain the extracellular matrix of bone.
Adipocytes: Fat cells.
Hematopoietic Stem Cells: Undifferentiated cells that give rise to any type of blood cell.
Red Blood Cells: Differentiated, anucleated cells that specialize in carrying oxygen throughout the blood.
White Blood Cells: Differentiated blood cells that carry out immune functions.
Mast Cells: A type of white blood cell that resides in connective tissue.
Macrophages: Phagocytic white blood cells.
Mesenchymal Stem Cells: Stem cells that give rise to every type of connective tissue.
Ground Substance: The medium through which solutes diffuse between blood capillaries and the cells.
Collagen Fibers: Provide connective tissue with tensile strength, anchoring capacity, and resistance to stretch.
Elastic Fibers: Long and thin fibers that allow for stretch and recoil of connective tissue, composed of elastin fibers.
Reticular Fibers: Short, fine, highly branched collagenous fibers that provide connective tissue with a “soft skeleton” of support.
Connective Tissue Proper: Composed of non-contiguous cells spread throughout an extracellular matrix of ground substance and fibers.
Loose Connective Tissue Proper: Protects organs and epithelial tissue. Contains more cells than fibers, and the fibers are loosely arranged, providing room for blood vessels and nerves.
Areolar Tissue: Composed of many cells spread throughout the ground substance with spacious fibers, whose majority of cells present are fibroblasts and fibrocytes, which make three fiber types. Additionally contains adipocytes, white blood cells, macrophages, and mast cells. Located underneath epithelial tissue and wraps around organs.
Adipose Tissue: Located in the hypodermis, breasts, abdomen, and surrounding organs such as the kidneys and the posterior aspect of the eyeball. Functions in insulation, protection, and as a reservoir of fuel.
Reticular Tissue: Found in lymphatic organs such as the spleen and lymph nodes, as well as in the liver, where it serves as a soft skeleton within the organ.
Dense Connective Tissue Proper: Offers strength. Contains more fibers than cells, and the fibers are densely arranged.
Tendons: Anchor muscles to bones.
Ligaments: Anchor bones to bones.
Aponeuroses: Attaches wide, flat muscles to bone or skin.
Perichondrium: A connective tissue layer, typically composed of dense irregular connective tissue.
Nervous Tissue: Responsible for controlling many of the body’s functions and mechanisms.
Neurons: Branched cells that transmit electrical signals from sensory receptors to control center neurons and back out to effector tissues.
Neuroglia: Support cells for neurons.
Skeletal Muscle: Consists of striated, long, cylindrical, multinucleated cells; it facilitates voluntary movement such as locomotion and environmental manipulation, and is found throughout the entire body.
Cardiac Muscle: Made up of branched, striated cells that interdigitate at specialized junctions called intercalated disks; its primary function is to propel blood, and it is located only in the walls of the heart.
Smooth Muscle: Composed of sheets of spindle-shaped cells with a central nucleus; it functions to propel substances (such as food, urine, and blood) and is found in the walls of hollow organs.
Intercalated Disks: Specialized cellular junctions in cardiac muscle that connect adjacent muscle cells, allowing for synchronized contraction by facilitating the transmission of electrical impulses and mechanical coupling.
Nervous Tissue
Nervous Tissue: Responsible for controlling many of the body’s functions and mechanisms.
Neurons: Branched cells that transmit electrical signals from sensory receptors to control center neurons and back out to effector tissues.
Neuroglia: Support cells for neurons.
Muscular Tissue
Muscular Tissue: Responsible for movement.
Skeletal Muscle: Striated, long, cylindrical, multinucleated cells that allow for voluntary movement.
Cardiac Muscle: Branched, striated cells with intercalated discs that propel blood and are found only in the heart.
Smooth Muscle: Spindle-shaped cells with a central nucleus that propel substances through hollow organs.
Epithelial Tissue
Simple Squamous Epithelium: Single layer of flattened cells with disc-shaped nuclei, allowing for fast diffusion or filtration.
Simple Cuboidal Epithelium: Single layer of cube-like cells with large, spherical nuclei, responsible for secretion and absorption.
Simple Columnar Epithelium: Single layer of tall, rectangular cells with oval nuclei, specialized for absorption and secretion.
Pseudostratified Columnar Epithelium: Single layer of cells appearing stratified due to nuclei at different heights, involved in secretion and movement of mucus.
Stratified Squamous Epithelium: Multiple layers of flattened cells for protection from abrasion.
Stratified Cuboidal Epithelium: Rare, multiple layers of cube-shaped cells, specialized in secretion.
Stratified Columnar Epithelium: Rare, multiple layers of columnar cells, functioning in secretion.
Transitional Epithelium: Multiple layers of dome-shaped cells that stretch and distend, found only in the urinary system.
Loose Connective Tissue
Areolar Tissue: A loose connective tissue with a spacious fiber network that cushions, protects, and anchors other tissue types.
Adipose Tissue: Fat storage tissue composed of adipocytes, providing insulation, protection, and energy storage.
Reticular Tissue: Fibroblast-supported connective tissue forming a soft skeleton for organs like the spleen and lymph nodes.
Dense Connective Tissue
Dense Regular Connective Tissue: Tissue with parallel collagen fibers that provide tensile strength in one direction, found in tendons and ligaments.
Dense Irregular Connective Tissue: Tissue with collagen fibers arranged in multiple directions, allowing for tensile strength in various directions.
Elastic Connective Tissue: Tissue composed of collagen and elastic fibers, enabling stretch and recoil, found in large arteries and bronchi.
Cartilage
Hyaline Cartilage: Chondrocytes within a translucent extracellular matrix, providing reinforcement, cushioning, and flexibility.
Elastic Cartilage: Chondrocytes surrounded by a dense network of elastic fibers, providing shape and flexibility.
Fibrocartilage: Chondrocytes with thick collagen fibers, offering tensile strength and shock absorption.
Other Connective Tissues
Bone (Osseous Tissue): Hard, calcified connective tissue composed of osteocytes arranged in concentric circles, providing support, protection, and mineral storage.
Blood: A fluid connective tissue with erythrocytes, leukocytes, and platelets suspended in plasma, responsible for transport, immune defense, and clotting.
Here are the definitions:
Collagen Fibers
Definition: Thick, strong fibers made of collagen protein that provide tensile strength to connective tissues.
Elastic Fibers
Definition: Thin fibers made of elastin that provide flexibility and stretch to connective tissues.
Reticular Fibers
Definition: Thin, branching fibers made of collagen that form a supportive network in soft tissues.
Ground Substance
Definition: The gel-like material in connective tissue that fills spaces between cells and fibers, allowing diffusion of nutrients and waste.
Fibroblasts
Definition: Cells in connective tissue that produce fibers and ground substance.
Mast Cells
Definition: Cells that release histamine and other chemicals during allergic and inflammatory responses.
Fibrocytes
Definition: Mature, less active fibroblasts that maintain the fibers and matrix of connective tissue.
Tensile Strength
Definition: The ability of a material to resist being pulled apart or stretched.
Lacunae
Definition: Small spaces or cavities in cartilage and bone tissue that house cells.
Chondrocytes
Definition: Mature cells in cartilage that produce and maintain the extracellular matrix.
Osteocytes
Definition: Mature bone cells that maintain the bone matrix.
Osteons
Definition: Structural units of compact bone, consisting of concentric layers of matrix around a central canal.
Central Canal
Definition: A channel in the center of an osteon that contains blood vessels and nerves.
Erythrocytes
Definition: Red blood cells responsible for transporting oxygen throughout the body.
Leukocytes
Definition: White blood cells that defend the body against infections and foreign substances.
Thrombocytes
Definition: Platelets involved in blood clotting.
Plasma
Definition: The liquid component of blood that transports cells, nutrients, and waste products.
Stem Cells and Germ Layers
Types of Stem Cells:
Totipotent: Can differentiate into any cell type, including extra-embryonic tissues (e.g., placenta). Found in early embryos.
Pluripotent: Can differentiate into any cell type except extra-embryonic tissues (e.g., embryonic stem cells).
Multipotent: Can differentiate into a limited number of related cell types (e.g., hematopoietic stem cells that form blood cells).
Unipotent: Can only differentiate into one specific cell type (e.g., muscle stem cells).
Germ Layers and Their Derivatives:
Ectoderm: Forms the skin (epidermis) and the nervous system (brain, spinal cord).
Mesoderm: Forms muscles, bones, blood vessels, connective tissues, and the heart.
Endoderm: Forms internal organs such as the digestive and respiratory systems (e.g., lungs, liver, intestines).
Tissue Types and Characteristics
Four Main Tissue Types:
Epithelial Tissue:
Structure: Cells are closely packed with minimal extracellular matrix; forms sheets or layers.
Function: Protection, absorption, secretion, and filtration.
Location: Skin, lining of internal organs (digestive tract, lungs), glands.
Connective Tissue:
Structure: Sparse cells embedded in extracellular matrix; matrix includes fibers (collagen, elastin) and ground substance.
Function: Supports, binds, and insulates organs and tissues; transports substances (blood).
Location: Tendons, ligaments, cartilage, bone, blood.
Nervous Tissue:
Structure: Neurons with long processes (axons, dendrites) and supporting neuroglia cells.
Function: Transmits electrical signals for communication, coordination, and control.
Location: Brain, spinal cord, peripheral nerves.
Muscle Tissue:
Structure: Elongated cells (fibers) capable of contracting.
Function: Movement (voluntary and involuntary).
Location: Skeletal muscle (attached to bones), cardiac muscle (heart), smooth muscle (walls of hollow organs).
Key Components of Connective Tissue (CT)
Ground Substance:
Definition: A gel-like material that fills spaces between cells and fibers, enabling nutrient and waste exchange.
Cells in Connective Tissue:
Fibroblasts: Produce fibers (collagen, elastin) and ground substance.
Adipocytes: Fat cells for energy storage and insulation.
Mast Cells: Release histamine and heparin during inflammatory responses.
Chondrocytes: Cartilage cells that maintain the matrix.
Osteocytes: Bone cells that maintain the bone matrix.
Synthesis of Collagen Fibers:
Collagen fibers are produced by fibroblasts and are essential for the strength and integrity of tissues.
Tissue Identification
Recognizing tissue type:
Epithelial: Closely packed cells, often form layers or sheets.
Connective: Cells spaced out with extracellular matrix, fibers visible.
Nervous: Neurons with long processes and supportive neuroglia.
Muscle: Elongated cells (striated or smooth).
Integumentary System
Structures and Functions of the Integumentary System:
Skin (Epidermis and Dermis):
Epidermis: Outer layer, protects against dehydration and pathogens, made of stratified squamous epithelium.
Dermis: Inner layer containing blood vessels, nerves, hair follicles, and connective tissue (collagen and elastin).
Accessory Structures:
Hair: Provides protection and regulates body temperature.
Sweat Glands: Produce sweat for thermoregulation.
Sebaceous Glands: Secrete sebum to lubricate and protect the skin.
Nails: Protect the fingers and toes.
Basic Terminology (As Discussed in Lecture)
Atrophy: The decrease in size or function of a tissue or organ.
Hypertrophy: The increase in size of a tissue or organ due to the enlargement of its cells.
Epidermis and Dermis Layers
Epidermis Layers:
Stratum Corneum: Outermost layer, composed of dead keratinized cells.
Stratum Lucidum: Found in thick skin (palms, soles).
Stratum Granulosum: Cells start to die and form a waterproof barrier.
Stratum Spinosum: Cells connected by desmosomes, providing strength.
Stratum Basale: Deepest layer, where new cells are formed.
Dermis Layers:
Papillary Layer: Thin, loose connective tissue; contains capillaries and sensory neurons.
Reticular Layer: Dense irregular connective tissue; contains collagen and elastin fibers.
Skin Conditions and Healing
Types of Burns:
First-Degree: Affects only the epidermis (redness, pain).
Second-Degree: Affects epidermis and part of the dermis (blisters, swelling).
Third-Degree: Affects all layers, can cause charring and loss of sensation.
Bruising Scale: Describes the stages of bruising based on color changes from red to purple to green and yellow as blood is broken down.
Phases of Healing:
Inflammatory Phase: Immediate response to injury (swelling, redness).
Proliferative Phase: Tissue repair and regeneration (new tissue forms).
Maturation Phase: Tissue remodels and strengthens.
Clinical Tools and Skin Cancer
Rule of Nine: Used to estimate the extent of burn injuries by dividing the body into sections representing 9% of total body surface area.
ABCD Tool for Melanomas:
A: Asymmetry
B: Border irregularity
C: Color variation
D: Diameter (larger than 6mm)
Types of Skin Cancers:
Basal Cell Carcinoma: Most common, slow-growing, rarely metastasizes.
Squamous Cell Carcinoma: Can metastasize, found in sun-exposed areas.
Melanoma: Most dangerous, can metastasize rapidly; check using the ABCD method.
Here are the extracted definitions:
Chemical Barrier: Skin secretions and immune cells that prevent pathogen proliferation.
Physical Barrier: Keratin and glycolipids that protect against water loss and harmful substances.
Biological Barrier: Special immune cells (e.g., dendritic cells, macrophages) that attack pathogens.
Temperature Regulation: Mechanisms like blood vessel dilation, sweating, and constriction to maintain body temperature.
Dehydration Prevention: Keratinized cells that reduce water loss from deeper skin layers.
Sensory Information: Cutaneous receptors that detect environmental changes and send information to the nervous system.
Vitamin D Synthesis: The process by which UV rays convert provitamin D3 into vitamin D3 for calcium absorption and inflammation regulation.
Blood Reservoir: Dermal blood vessels that store 5-10% of the body’s blood volume, which can be redirected as needed.
Excretion: Sweat glands that excrete waste products such as nitrogenous wastes and salts.
Skin: Composed of the epidermis, dermis, and hypodermis.
Thin Skin: Skin covering most of the body.
Thick Skin: Skin found on the palms, fingers, soles, and toes.
Epidermis: The outer layer of the skin.
Dermis: The middle layer of the skin.
Hypodermis: The deep layer of the skin.
Skin Changes with Age: Skin thins, loses elasticity, and becomes more prone to damage like sagging, bruising, and ulcerations.
Decubitus Ulcers (Bedsores): Skin damage caused by prolonged pressure, reducing blood flow, and leading to tissue damage. Common in immobile patients.
Pressure Ulcers: A significant healthcare cost, with $11 billion spent annually on treatment. Preventative strategies include repositioning and skin care education.
Epidermis: The outermost layer of skin, avascular, composed of keratinocytes, melanocytes, dendritic cells, tactile cells, and basal cells. It provides a barrier and is involved in cell regeneration.
Stratum Basale: The deepest layer of the epidermis, where cell division and regeneration occur, anchoring the epidermis to the dermis.
Stratum Spinosum: Layer above the stratum basale, consisting of keratinocytes connected by desmosomes, involved in keratin production and water retention.
Stratum Granulosum: Layer with flattened keratinocytes that form a water-resistant barrier, starting cell degeneration.
Stratum Lucidum: A thin, transparent layer found only in thick skin, providing an additional water barrier.
Stratum Corneum: The outermost layer of dead, keratinized cells that protect against damage and water loss.
Dermis: The layer beneath the epidermis containing blood vessels, lymphatic vessels, nerves, and hair follicles. It has two layers: the papillary and reticular layers, providing support, strength, and sensory functions.
Papillary Layer: The upper layer of the dermis made of areolar connective tissue, supporting the epidermis and containing sensory receptors.
Reticular Layer: The deeper layer of the dermis, made of dense irregular connective tissue, providing strength and elasticity.
Hypodermis: The deep layer beneath the dermis, made of adipose tissue, providing insulation, shock absorption, and hormone synthesis. It contains blood vessels and nerves.
Keratinocytes: Main cells of the epidermis
Melanocytes: Highly differentiated cells that produce the pigment melanin
Epidermal dendritic cells: Specialized macrophages that help activate the immune system
Tactile (Merkel) cells: Oval-shaped mechanoreceptors in the basal layer of the epidermis that sense light touch
Basal cells: Cuboidal-shaped stem cells that give rise to keratinocytes
Desmosomes: Specialized junctions that connect adjacent cells, providing mechanical strength by linking cytoskeletons of neighboring cells.
Keratin: A fibrous structural protein found in skin, hair, and nails that provides strength, durability, and water resistance.
Dendritic Epidermal Cells: Immune cells in the epidermis that help detect and respond to pathogens.
Glycolipids: Lipid molecules with carbohydrate chains that contribute to the skin's water barrier by forming a protective layer.
Lamellar Granules: Membrane-bound structures in keratinocytes that release lipids to form a water-resistant barrier in the skin.
Macrophages, Mast Cells, White Blood Cells: Immune cells in the dermis that help defend against infections and promote inflammation during tissue repair.
Capillary Loop: Small blood vessels located in the dermis that provide oxygen and nutrients to the epidermis and help with waste removal.
Meissner’s Corpuscles: Specialized sensory receptors in the papillary layer of the dermis that detect light touch.
Pacinian Corpuscle: A sensory receptor in the dermis that detects deep pressure and vibration.
Superficial Fascia: A connective tissue layer located just beneath the skin, also known as the hypodermis, that connects the skin to underlying structures.
Subcutaneous Layer: The deepest layer of skin, primarily composed of adipose tissue, providing insulation, shock absorption, and storing fat.
Blood Vessels: Tubular structures that carry blood throughout the body, providing oxygen and nutrients to tissues and removing waste products.
Lymph Vessels: Tubular structures that carry lymph, a fluid containing immune cells, throughout the body, playing a key role in immune function and fluid balance.
Nerves: Bundles of fibers that transmit electrical signals between the brain, spinal cord, and other parts of the body, enabling sensation and motor control.
Cleavage Lines: Orientation of collagen and elastic fibers in the skin, important for wound healing and reducing scarring.
Friction Ridges: Epidermal elevations on the hands and feet that improve grip and leave fingerprints; unique to each individual.
Flexure Lines: Folds in the skin found on palms, fingers, soles, and toes, which anchor the skin and assist with gripping.
Melanin: Pigment produced by melanocytes that protects against UV damage and gives skin its color.
Carotenoids: Pigments obtained from the diet (e.g., carrots) that act as antioxidants and contribute to skin color.
Hemoglobin: Protein in blood that gives skin a pinkish hue due to blood flow.
Albinism: Genetic condition characterized by a lack of melanin, resulting in light skin, hair, and eyes.
Pallor: Pale skin caused by stress, anemia, or low blood pressure.
Jaundice: Yellowing of the skin due to liver disorders and elevated bilirubin levels.
Hematoma: Blood clot under the skin, commonly caused by trauma or surgery, resulting in bruising.
Cyanosis: Bluish discoloration of the skin due to insufficient oxygen, affecting lips, fingers, and toes.
Eccrine Sweat Glands: Sweat glands found all over the body, especially on palms, soles, and forehead; involved in thermoregulation by releasing water for cooling.
Apocrine Sweat Glands: Sweat glands found in axillary and anogenital areas, associated with hair, become active during puberty, and may function as sexual scent glands.
Ceruminous Glands: Specialized apocrine sweat glands located in the external ear that produce cerumen (earwax) for protection.
Mammary Glands: Specialized apocrine sweat glands located in the breasts that produce milk.
Sebaceous Glands: Oil glands found throughout the skin, except on palms and soles; secrete sebum, which waterproofs and protects skin and hair.
Holocrine Secretion: A method of secretion where cells burst to release their contents, as seen in sebaceous glands.
Hair: Structure composed of dead keratinized cells that provides protection against trauma, UV radiation, and heat loss; the hair follicle extends into the dermis.
Arrector Pili Muscle: Muscle attached to hair follicles that causes goosebumps when contracted.
Acne: Skin condition caused by clogged hair follicles with oil and dead skin, leading to pimples, blackheads, and whiteheads.
Nails: Scalelike modifications of the epidermis found on fingers and toes, providing protection and aiding in fine motor tasks.
Bromhidrosis: Body odor caused by the breakdown of fatty substances and proteins in sweat by bacteria.
Cerumen: Waxy substance produced by ceruminous glands in the external ear for protection.
Sebum: Oily substance secreted by sebaceous glands that waterproofs and protects the skin and hair.
Holocrine Secretion: A secretion process where cells rupture to release their contents, as seen in sebaceous glands.
Hair Follicle: The structure in the skin that houses the hair root and extends into the dermis.
Hair Bulb: The base of the hair follicle, where hair growth begins and where cells divide to form new hair.
Arrector Pili Muscle: Small muscle attached to hair follicles that causes goosebumps when contracted.
Acne: A skin condition where hair follicles are clogged with oil and dead skin cells, leading to pimples, blackheads, and whiteheads.
Hair Shaft - The visible portion of hair extending above the skin.
Arrector Pili Muscle - A small muscle attached to hair follicles that causes hair to stand up (goosebumps).
Nerve - A bundle of fibers transmitting electrical impulses, present in the skin for sensation.
Sebaceous Gland - Gland that secretes sebum (oil) to lubricate the skin and hair.
Hair Root - The portion of the hair beneath the surface of the skin.
Hair Bulb in Follicle - The base of the hair follicle where hair cells are produced.
Dermal Papilla - A small projection of the dermis into the epidermis, providing nutrients to the hair follicle.
Blood Vessels - Blood-carrying structures providing nutrients and oxygen to the skin and hair follicles.
Medulla - The innermost layer of the hair shaft, composed of soft keratin.
Cortex - The middle layer of the hair, containing pigment and providing strength.
Cuticle - The skin at the base of the nail that protects the area between the nail and nail bed from infections.
Nail Matrix - The tissue at the base of the nail that produces new nail cells.
Root of Nail - The portion of the nail under the skin, where new growth occurs.
Proximal Nail Fold - The fold of skin at the base of the nail.
Eponychium (Cuticle) - The thickened layer of skin at the base of the nail.
Body of Nail - The visible portion of the nail.
Nail Bed - The skin beneath the nail plate, rich in blood vessels.
Free Edge of Nail - The portion of the nail that extends beyond the fingertip and is not attached to the nail bed.
Phalanx (Bone of Fingertip) - The bones of the fingers that form the fingertip.
Stratum Germinativum - The deepest layer of the epidermis, where new skin cells are formed.
Whitehead - A type of acne lesion formed when a pore becomes clogged with sebum and dead skin cells, causing a closed comedo.
Blackhead - An open comedo (clogged pore) where the contents oxidize and darken.
Open Comedo - A clogged pore or hair follicle that remains open, leading to a blackhead.
Papule - A small, raised bump on the skin, typically a type of pimple.
Pustule - A pimple containing pus, often resulting from bacterial infection.
Inflammation - The body’s response to injury or infection, characterized by redness, heat, swelling, and pain.
Skin Cancer:
Definition: Uncontrolled cell growth leading to malignant tumors in the skin, including basal cell carcinoma, squamous cell carcinoma, and melanoma.
Basal Cell Carcinoma:
Definition: The most common and least malignant form of skin cancer, affecting cells in the stratum basale. It is 99% curable with surgical removal.
Squamous Cell Carcinoma:
Definition: A skin cancer affecting keratinocytes in the stratum spinosum, commonly found in sun-exposed areas. It is treated with surgical removal and/or radiation therapy.
Melanoma:
Definition: The rarest but most deadly type of skin cancer, affecting melanocytes and spreading aggressively. It is resistant to chemotherapy and is treated with surgical excision and immunotherapy.
Burns:
Definition: Tissue damage caused by heat, UV rays, radiation, chemicals, or electricity. Burns can lead to dehydration, infection, and severe complications. They are classified by the depth of skin damage.
First Degree Burn:
Definition: A burn affecting only the epidermis, causing redness, swelling, and mild pain, commonly from sunburns or minor scalds.
Second Degree Burn:
Definition: A burn damaging the epidermis and upper dermis, causing blisters, redness, and severe pain.
Third Degree Burn:
Definition: A burn that destroys the full thickness of the skin, requiring skin grafting. There is no pain initially due to nerve damage, and the skin appears gray, white, black, or red.
Fourth Degree Burn:
Definition: A burn that extends beyond the skin into fat tissue, often requiring amputation or intensive treatment. It has a charred appearance.
Fifth Degree Burn:
Definition: A burn that reaches muscle tissue, often fatal if extensive, requiring amputation. The skin and muscle are completely burned away, and bone may be exposed.
Sixth Degree Burn:
Definition: The most severe burn, reaching the bone, almost always fatal. Immediate medical intervention is required, and it typically results in death or amputation.
Dermatitis (Eczema):
Definition: Inflammation of the skin causing redness, itching, and rash, often triggered by allergies, irritants, or genetic factors.
Cellulitis:
Definition: A bacterial infection affecting the dermis and hypodermis, causing redness, swelling, and pain. It can spread if untreated, requiring antibiotics.
Cellulite:
Definition: Dimpling of the skin caused by subcutaneous fat pushing into the dermis, commonly seen on thighs, hips, buttocks, and belly. It is more common in women due to fat distribution.
Striae (Stretch Marks):
Definition: Scars resulting from the tearing of the dermis, often caused by rapid growth, pregnancy, or weight changes, and influenced by hormonal changes.