Chapter Four: Tissue Organization (Openstax - Anatomy and Physiology BIO168)

Cell

The basic unit of organisms on the microscopic level

Tissue

Composed of typically specialized cells that perform a function within the body; tissues make up organs

Epithelial tissue

Sheets of cells that cover exterior surfaces of the body, line internal cavities and passageways; functions in protection and selective transfer of material

Connective tissue

Binds the cells and organs of the body together; provides protection, support, and integration

Muscle tissue

Excitable tissue that responds to stimulation and contracts to provide movement; found in musculoskeletal, cardiovascular, and digestive systems

Nervous tissue

Tissue that occurs in the nervous system, making up neurons; allows propagation of electrochemical signals

Ectoderm

Germ layer that gives rise to epidermis, skin glands, some cranial bones, pituitary, adrenal medulla, nervous system, and anus

Mesoderm

Germ layer that gives rise to connective tissues, bone, cartilage, blood, endothelium, muscle, synovial membranes, serous membranes, kidneys, and gonad linings

Endoderm

Germ layer that gives rise to lining of airways and digestive system (except mouth and distal part), rectum, anal canal, digestive glands, endocrine glands, and adrenal cortex

Epithelial membrane

Composed of epithelium attached to a layer of connective tissue

Mucous membrane

Produces mucus which lines body cavities

Serous membrane

Lines the ventral cavity of the body and contains serous fluid

Cutaneous membrane

Also called the skin; unique epithelial membrane

Synovial membrane

Found in joints; releases liquids and lacks epithelial cells

Basal lamina

Mixture of glycoproteins and collagen fibers that allows epithelial cells to attach to reticular lamina

Reticular lamina

Tissue always found under epithelial cells

Avascular

Lacking blood vessels; describes epithelial tissue

Tight junctions

Cell junctions that solidify cell polarity

Anchoring junctions

Stabilize epithelial cells by providing strong and flexible connections

Desmosomes

Occur in patches; have structural proteins on inner surface and adhesion molecule cadherin

Hemidesmosomes

Link cells to extracellular matrix; have integrins rather than cadherins

Adherens junctions

Use cadherins or integrins; characterized by presence of contractile protein actin

Cadherins

Project through cell membrane to link with cadherin molecules of adjacent cells

Integrins

Adhesion proteins that link cells to extracellular matrix

Squamous

Fish scale-like cell shape

Cuboidal

Cube-shaped cells

Columnar

Rectangular cells that are taller than wide

Simple epithelium

One layer of cells

Stratified epithelium

Two or more layers of cells

Endothelium

Lines lymphatic and cardiovascular systems

Simple squamous epithelium

Makes up serous membrane lining body cavities and internal organs

Stratified squamous epithelium

Contains squamous cells at apical surface with cuboidal or columnar cells at basal surface; found in mouth and skin

Simple cuboidal epithelium

Functions in secretion, absorption, and protection; found in ovaries and kidneys

Stratified cuboidal epithelium

Stronger barrier with two layers

Ciliated columnar epithelium

Found in digestive tract and female reproductive tract; helps remove particulate matter

Pseudostratified columnar epithelium

Found in respiratory tract; nuclei arranged differently than simple columnar

Goblet cells

Secrete mucus; not all columnar epithelial cells with goblet cells need cilia

Stratified columnar epithelium

Found in male and female urethrae and ducts of some glands

Transitional epithelium

Found in urinary system; aids contractions and movements of the bladder

Endocrine glands

Ductless glands diffused through bloodstream to target cells

Exocrine glands

Release content outside of body such as breast milk, sweat, and mucous

Goblet cells

Unicellular exocrine glands

Merocrine secretion

Secretory vesicles travel to cell edge and release secretion by melding with cell membrane

Apocrine secretion

Top third of cell containing secretory vesicles pinches off and disconnects

Holocrine secretion

Cell forms finger-like projections that bud off; mature cell eventually dies and becomes secretory product

Connective tissue proper

Provides protection, strength, structure, and linking; found almost everywhere in body

Loose connective tissue

Loosely organized fibers

Areolar tissue

Loose tissue mainly for filling spaces between organs and tissues to protect them

Adipose tissue

Functions in energy storage, insulation, and heat regulation; found around abdomen and muscles

Reticular tissue

Connective tissue scattered and mixed with others; provides structure or stroma to sustain immune system organs

Dense connective tissue

Reinforced by bundles of fibers that provide tensile strength, elasticity, and protection

Regular elastic tissue

Stretching tissue that is parallel; found in ligaments and vascular system

Irregular elastic tissue

More random arrangement of fibers; endures tension and forces from many angles

Supportive connective tissue

Provides strength and structure to body; mainly found in musculoskeletal system

Cartilage

Strong and flexible tissue that protects bones and joints

Hyaline cartilage

Most common cartilage in body; lines joints; helps with smooth movement

Fibrocartilage

Tough cartilage made of thick fibers; least flexible and most strong; found in knee, spine, and tendons

Elastic cartilage

Most flexible cartilage; provides ability to bend and move; found in ears and larynx

Bones

Calcified structure that provides standing structure to the body

Compact bone

Denser material used to create much of the hard structure of the skeleton

Cancellous bone

Soft, spongy bone found on inside of bones; bears bone marrow and RBC formation

Fluid connective tissue

Performs circulation and maintains stability or homeostasis

Blood

Substance that circulates through body transporting hemoglobin, infection-fighting components, and clotting properties

Lymph

Fluid of the immune system; fights infection, delivers oxygen and proteins, picks up debris

Tendinitis

Inflammation of the tendons caused by straining or injury

Excitability

Ability to respond to a stimulus

Cardiac muscle

Found in heart; contracts and pumps blood; involuntary; attaches via intercalated discs

Skeletal muscle

Found in skeleton; supports bones and provides movement; voluntary; striated

Smooth muscle

Lines hollow organs; contracts involuntarily to regulate digestion, respiration, secretions, and blood flow

Neurons

Basic cell of nervous system that sends messages

Neuroglia

Supporting cells of nervous system

Multipolar neurons

Have two or more dendrites and one axon; most abundant; found in CNS

Unipolar neurons

Have only a single process extending from cell body; found in PNS and spinal cord

Bipolar neurons

Possess single dendrite and axon with cell body; found in sensory pathways like retina and olfactory epithelium

Astrocyte

Major type of neuroglia in CNS

Oligodendrocyte

Major type of neuroglia in CNS

Schwann cell

Major type of neuroglia in PNS

Inflammation

Body's response to injury; signs include redness, swelling, pain, and local heat

Apoptosis

Programmed cell death that does not initiate inflammatory response

Histamine

Chemical that initiates inflammation and directs attention to inflammation site

Wound healing

Process involving clotting, scab formation, epithelial cell production and filling, then thickening and maturation

Telomeres

Shorten each time cells divide; affected by aging causing decreased cell division quality

Differentiated cells in a developing embryo derive from ________.

ectoderm, mesoderm, endoderm

The process by which a less specialized cell matures into a more specialized cell is called ________.

differentiation

Which of the following central nervous system cells regulate ions, regulate the uptake and/or breakdown of some neurotransmitters, and contribute to the formation of the blood-brain barrier?

astrocytes

Striations, cylindrical cells, and multiple nuclei are observed in ________.

skeletal muscle only

In adults, new connective tissue cells originate from the ________.

mesenchyme

Ligaments connect bones together and withstand a lot of stress. What type of connective tissue should you expect ligaments to contain?

dense irregular connective tissue

Under the microscope, a tissue specimen shows cells located in spaces scattered in a transparent background. This is probably ________.

hyaline cartilage

Connective tissue is made of which three essential components?

cells, ground substance, protein fibres

The ________ exocrine gland stores its secretion until the glandular cell ruptures, whereas the ________ gland releases its apical region and reforms.

holocrine; apocrine

Which of the following is the epithelial tissue that lines the interior of blood vessels?

simple squamous

Which of the following lines the body cavities exposed to the external environment?

mucosa

In observing epithelial cells under a microscope, the cells are arranged in a single layer and look tall and narrow, and the nucleus is located close to the basal side of the cell. The specimen is what type of epithelial tissue?

columnar