Unit 1 Ana/Phys Key Terms

Nucleolus

• Dense, spherical structure made up of ribosomal RNA (rRNA) and proteins

• Area where ribosomes are assembled

• Helps regulate the cell cycle

Golgi Apparatus

• Membrane-bound organelle in eukaryotic cells made up of flattened sacs (cisternae)

• Modifies, sorts, and packages proteins + lipids received by the ER

• Packages into vesicles for transport

Lysosome

• Membrane-bound organelle filled with digestive enzymes that break down waste, cellular debris, and foreign substances

• Helps break down substances, destroy invaders, and remove damaged organelles

• Can trigger apoptosis

Peroxisomes

• Small, membrane-bound organelle containing enzymes (oxidases and catalase) to break down toxic substances

• Metabolizes fat

• Helps break down harmful substances and detoxification

Microtubules

• Hollow, cylindrical structures made up of the protein tubulin

• Part of the cytoskeleton, giving the cell its shape and framework

• Also important in intracellular transport, cell division, and movement

Microfilaments

• Thin, solid protein fibers made up of actin

• Part of the cytoskeleton, helping maintain the cell’s shape

• Assist in endocytosis + exocytosis

• Forms the ring that splits the cell apart during cytokinesis

Intermediate filaments

• Rope-like protein fibers that provide mechanical strength and structural stability to cells

• Important in the formation of cell junctions (especially desmosomes)

• Help resist tension, preventing cells from being ripped apart

Centrioles

• Small, cylindrical structures made up of microtubule

• Found in pairs in the centrosome of animal cells

• Help organize microtubules in mitotic spindle during mitosis

• Helps form cilia and flagella

Characteristics of Epithelium

• 

  Cells fit closely together and bounded by tight junctions + desmosomes

• Cell surface is exposed

• Cells are anchored to basement membrane, which holds them like glue

• Cells have no blood supply (avascular) - rely on underlying tissue for nutrients + blood

Simple squamous epithelia

• Single layer of flat, thin cells with centrally located nuclei

• Allows for rapid diffusion, filtration, and exchange of materials

• Found in lungs and kidneys

• Also secretes in serious membranes as well

Stratified squamous epithelia

• Multiple layers of cells, with topmost layer flat (squamous) while deeper layers can be cuboidal or columnar

• Most common stratified epithelium

• Provides protection against friction and abrasion

• Lines surface of skin, mouth, and esophagus

Simple cuboidal epithelia

• Single layer of cube-shaped cells with centrally located nuclei

• Specializes in absorption and secretion

• Common in glands and ducts (salivary glands, sweat glands and pancreas)

Simple columnar epithelia

• Single layer of tall, rectangular (column-shaped) cells with nuclei located near base of cell

• Specializes in secretion, absorption, and protection

• Found through the digestive tracts and includes goblet cells (produce mucus)

Pseudostratified columnar epithelia

• Single layer of columnar cells that appears multilayered b/c nuclei are at varying heights, but every cell touches basement membrane

• Specializes in secretion and movement of mucus

• Found in respiratory tracts (trachea, bronchi)

• Has goblet cells (produces mucus) and cilia (moves mucus)

Stratified cuboidal epithelia

• Multiple layers of cube-shaped cells, top layer is cuboidal

• Provides protection and some secretion

• Found in ducts of swear glands, mammary glands, and salivary glands

• Not common

Stratified columnar epithelia

• Multiple layers of cube-shaped cells; top layer is columnar (lower layers can be cuboidal)

• Provides protection and some secretion

• Found in lining of large ducts in large glands (salivary glands, parts of male urethra)

• Not common

Bone/Osseous (Connective Tissue)

• Connective tissue that provides structural support and protection for body

• Can be soft or hard

• Osteocytes found within cavities (lacunae) 

• Lacunae surrounded by hardened matrix (due to calcium salts) with large amount of collagen fibers

Cartilage (Connective Tissue)

• Flexible, semi-rigid connective tissue providing support and cushioning of body

• Chondrocytes found within cavities (lacunae)

• Types of cartilage depends on protein fibers/density of matrix

• Three types: hyaline, elastic, and fibrocartilage

Dense/Fibrous (Connective Tissue)

• Connective tissue with high density of collagen fibers, making it strong and resistant to stretching

• Fibroblasts (cells) produce collagen fibers

• Forms tendons and ligaments

Areolar/loose (Connective Tissue)

• Loosely organized connective tissue with cells (fibroblast. macrophage), fibers, and ground substances that fills space and cushions organs

• Provides flexible support, cushioning, and diffusion of nutrients/waste

• Rich in nutrients and blood vessels

• Most common connective tissue

Adipose (Connective Tissue)

• Type of connective tissue specialized for storing lipids and energy storage, cushioning, and insulation

• Adipocytes (fat cells) found within matrix

• Found in subcutaneous layers beneath skin and around major organs (hearts and kidneys)

• Secretes leptin (hormone) to regulate appetite

Reticular (Connective Tissue)

• Delicate network of reticular fibers, providing support and framework for soft organs

• Reticular cells produce reticular fibers which form web-like network within hollow organs

• Found in lymph tissues, spleen, kidney, liver, and pancreas

Vascular Tissue (Blood)

• Connective tissue specialized for transporting fluids, nutrients, gases and wastes throughout body

• Blood cells found within fluid matrix (plasma)

• Red blood cells (oxygen) and white blood cells (defense)

Lymph Tissue

• Connective tissue specialized in immune cell activation, proliferation, and filtration of pathogens

• Contains no red blood cells. White blood cells are in a fluid matrix (lymph)

• Found in spleen, tonsils, thymus, and lymph node

• Part of the immune (lymphatic) system

Skeletal Muscle (Tissue)

• Voluntary, striated muscle tissue attached to bones for movement

• Cells are long, cylindrical, and multinucleated

• Contains protein fibers (actin and myosin) that form the vertical “striations” within muscle tissue

• Forms Muscular System

Cardiac Muscle (Tissue)

• Involuntary muscle tissue that is striated and found only in the wall of heart

• Short cells that have a single nucleus and branch

• Cells fit tightly together through junctions (intercalated discs) that allow free movement of ions between cells

• Contracts rhythmically to pump blood

Smooth Muscle (Tissue)

• Muscle tissue that has no striations and is responsible for involuntary muscle control

• Causes constriction or dilation of organs

• Found in walls of hollow organs (stomach, blood vessels (arteries + veins), intestines, and uterus)

• Cells have a single nucleus and are tapered at each end

Nervous Tissue

• Tissue specialized to produce, conduct, and received electrical impulses

• Cells are long and large (neurons)

• Also contains neuroglia (glial cells) that support the neurons

• Found in Central Nervous System and Peripheral Nervous System

Osteocytes

• Mature bone cells that maintain bone matrix

• Monitors and maintain mineral content of bone, helping repair bone damage

• Found within lacunae in bone tissue

Lacunae

• Small spaces/cavities within cartilage or bone tissue that house and protect cells

• Protects chondrocytes in cartilage, osteocytes in bone
  Allow cells to maintain extracellular matrix around them

Collagen

• Most abundant protein in body, forming strong fibers in connective tissue

• Gives strength and shape to tissues, resists stretching forces, and supports skins, bones, tendons, ligaments, cartilage, and organs

Chondrocytes

• Mature cartilage cells that maintain and produce cartilage extracellular matrix (fibers and ground substances)

• Produces collagen for cartilage structure

• Maintains health of cartilage tissue

• Found in cartilage tissue

Hyaline cartilage

• Most common type of cartilage, with glossy, smooth matrix made up of collagen

• Provides flexible support, smoother surfaces for joint movement, and growth of bones

• Found in nose, trachea, bronchi, and larynx

Fibrocartilage

• Type of cartilage that is very tough and durable, containing thick bundles of collagen fibers

• Provides strong support + absorbs force

• Found in discs between vertebrae, between pelvic bones
  

Elastic cartilage

• Type of cartilage that is flexible and resilient

• Contains dense network of elastic fibers + collagen fibers

• Consists of chondrocytes housed in lacunae

• Found in external ear, larynx, epiglottis

Fibroblasts

• Type of connective tissue that produces and maintains extracellular matrix

• Synthesizes fibers + ground substances (gel-like material between cells and fibers) that form framework of tissues

• Creates fibers (collagen, elastic fibers, reticular, etc.)

• Found every in connective tissues around body

Subcutaneous tissue

• Layer of connective tissue and fat beneath dermis of skin

• Consists of adipose tissue (fat), loose connective tissue, and fibrous bands

• Helps maintains body temperature, protecting underlying muscles/organs/bones

• Fat acts as reserve for energy

Reticular fibers

• Thin, branching fibers of connective tissue made up of collagen to provide supportive network in soft tissues

• Forms reticulum (network) rather than bundles

• Support organs’ structures while allowing flexibility

• Found in bone marrow, liver, pancreas, spleen

Myofibrils

• Long, cylindrical contractile structures inside muscle fibers

• Responsible for muscle contraction

• Generates force and movement by shortening during contraction

Neuroglia (Glial Cells)

• Supporting cells of nervous system

• Do not conduct nerve impulse, but help neurons function

• Maintains homeostasis, protects neurons, and assist in signal transmission

Globular proteins

• Proteins that are globular (spherical) in shape

• Soluble in water

• Helps in catalysis, transport, and regulation

Elastic fibers

• Fibers in connective tissue that are stretchable/flexible

• Returns to original length after being stretched

• Made up of elastin protein

• Found in skin, lungs, blood vessels, ligaments

Tendon

• Tough, fibrous connective tissue that connects muscle to bone

• Composed of collagen fibers

• Transmits force generated by muscles to move bones

Ligaments

• Tough, fibrous connective tissue that connects bone to bone at a joint

• Provides stability to joints + prevents excessive movement

• Composed of collagen fibers

Arteries

• Blood vessels that carry blood away from heart

• Thick, muscular, and elastic walls to handle high pressure from heart

• Carry oxygen-rich blood

• Distribute blood throughout body

Vein

• Blood vessels that carry blood toward heart

• Thinner walls, less muscular

• Carry oxygen-poor blood

• Have valves to prevent backflow

Involuntary muscle tissue

• Muscle tissue that works automatically, w/o conscious control

• Controls internal organ functions like heartbeat, digestion, and blood flow

• Ex. walls of intestine, uterus, bladder walls, respiratory airways

Voluntary muscle tissue

• Muscle tissue that you can consciously control

• Striated, attached to bones via tendons, and responsible for body movement + posture

• Ex. biceps, triceps, facial muscles, tongue

Striations

• Alternating bands seen in certain types of muscle tissues

• Due to arrangement of actin and myosin filaments within muscle fibers

• Found in skeletal and cardiac muscle tissues (not in smooth muscle)

Intercalated disc

• Specialized connections between cardiac muscle cells

• Allows for heart to work as a coordinated unit

• Keeps cardiac cells attached so they don’t pull apart during contraction, allowing for heart to beat

• Found only in heart muscles

Goblet cells

• Cell that works by itself to produce mucus (Designed for one job only)

• Releases secretion through duct or onto surface

• Mucus traps dust, microbe, debris, and protects lining of organs

• Found in trachea, bronchi, lining of intestines and stomach

Contractile Tissue

• Tissue specialized to shorten (contract) and generate force, enabling movement

• 3 types: skeletal muscle, cardiac muscle, and smooth muscle

• Use actin and myosin filaments that slide past each other to shorten cell

• Attached to bones, heart wall, walls of blood vessels + digestive tracts

Myosin

• Thick filament protein function

• Has a “head” region that binds to actin and uses ATP for energy

• Works with actin to help with muscle contraction

Actin

• Thin filament protein found in muscle fibers

• Filamentous and forms part of cytoskeleton

• Works with myosin to help with muscle contraction

Fibrosis

• The formation of excess fibrous connective tissue during wound healing

• Occurs when tissue is severely damage and cells cannot regeneration

• Tissue becomes less flexible and might lose function

Granulation tissue

• Connective tissue and blood vessels that form during the process of healing a wound

• Helps fill the wound bed and provide a foundation for new tissue growth and skin (epithelization)

• Looks pink/red, moist, and bumpy

Junctions

• Specialized structures that connect cells together or link them to extracellular matrix

• Critical for communication, adhesion, and maintaining tissue integrity

• Tight junctions seal cells together to prevent leakage between them

Desmosomes

• Type of cell junction that holds adjacent cells together

• Intermediate filaments inside cells hold them together (think of the desmosome as a coupler that connects train cars together)

• Keeps them from breaking apart under stress

Avascular

• Tissue of structure that does not contain blood vessels

• Relies on diffusion from nearby vascularized tissues (tissues with blood vessels) for nutrients and for removing waste

• Epithelial tissue is avascular, and they rely on basement membrane and connective tissue to get nutrients

Basement membrane

• Thin, specialized sheet of extracellular matrix lying between epithelial tissue and underlying connective tissue

• Provides support, anchors, and filtrates epithelium

• “Glues” epithelial tissue (tiles) to connective tissue (floor)

Transitional epithelium

• Type of tissue that can stretch and change shape without tearing

• Found in organs that expand and contract (ureters, urinary bladder)

• Cells near surface are rounded when relaxed, flattened when stretched

Endocrine + Exocrine glands

• Endocrine glands secrete hormones directly into bloodstream
  - No tubes, hormones travel directly though blood to target organs
  - Pituitary gland, thyroid glands, adrenal glands
  

• Exocrine glands secrete substances through ducts or to surface of body or into cavities
  - Have ducts (tubes) to carry secretions
  - Sweat glands, salivary glands

Phagocytes (White Blood Cells)

• Type of white blood cells that ingests (“eats”) and destroys foreign particles, bacteria, and dead/dying cells

• Part of the immune (lymphatic) system 

• Engulf and digest harmful particles through phagocytosis (endocytosis) 

• Contain a lot of lysosomes

Erythrocytes (Red Blood Cells)

• Type of red blood cell that specialize in transporting oxygen from lungs to body tissues and carry CO2 from tissues back to lungs

• Shaped like discs with a caved in center to increase surface area for exchange and flexibility

• Lacks a nucleus to carry more hemoglobin (oxygen-carrying protein)

Oocytes

• Immature female egg cell that develops in ovaries

• Develops into ova (eggs)

• Found in ovarian follicles in ovaries

Neurons (Nerve cells)

• Specialized nerve cells that transmit electrical + chemical signals through body

• Part of nervous system

• Soma (body), dendrites (receives input), axon (long fiber carrying impulses away from soma), myelin sheath (insulates/protects axon), axon terminals (releases neurotransmitters)