Chapter 5: The Human Tissues

Merged flashcards from Chapter 5, McGraw Hill Anatomy and Physiology Ninth Edition, by Kenneth S. Saladin.

Tissue growth

Increasing the number (hyperplasia) or size (hypertrophy) of existing cells

Hyperplasia

Growth through cell multiplication

Hypertrophy

Enlargement of preexisting cells

Neoplasia

Development of a tumor; benign or malignant

Differentiation

The development of a more specialized form and function by unspecialized tissue; often seen in embryonic development

Metaplasia

Changing from one type of mature tissue to another; pseudostratified columnar epithelium to stratified squamous in the bronchi of smokers

Embryonic stem cells

Undifferentiated cells that are not yet specialized and can turn into many others

Developmental plasticity

The ability of a stem cell to give rise to many cell types

Pluripotent embryonic stem cells

Stem cells that can develop into any type of cell in the embryo, not the organs

Totipotent embryonic stem cells

Stem cells that can develop into any type of a fully differentiated stem cell; very early

Adult stem cells

Undifferentiated cells in mature organs

Multipotent adult stem cells

Adult stem cells that can develop into two or more cell lines, like bone marrow

Unipotent adult stem cells

Adult stem cells that produce only one cell type, like cells producing sperm

Regeneration

The replacement of dead or damaged cell by the same type of cell as before

Fibrosis

The replacement of damaged cells with scar tissue; no function is restored

Stages of healing skin

• Vessels bleed into cut, releasing histamine and allowing plasma to flow better with antibodies and proteins

• Blood clot forms, protecting healing and blocking infection while leukocytes digest debris

• Blood capillaries sprout from nearby vessels, and the tissue heals with soft granulation tissues and new collagen as the blood clot is removed over 2 weeks

• Epithelial tissue multiplies and regenerates beneath the scab; connective tissue undergoes fibrosis which may show a scar for up to 2 years

Atrophy

The shrinkage of a tissue through loss in cell size or number; occurs in normal aging or lack of use

Necrosis

Tissue death due to trauma, toxins, or infections

Infarction

Sudden tissue death when blood supply is cut off

Gangrene

Tissue necrosis due to insufficient blood supply; often paired with infection—types include decubitus ulcers (bed sores), dry gangrene, wet gangrene (organ liquefaction), or gas gangrene (hydrogen bubbles in tissues)

Apoptosis

Programmed cell death to maintain optimal tissue function

Stem cell controversy

While embryonic stem cells have lots of potential, they are also limited by their ability to give rise to living beings

Cell junctions

The connections between two cells; they are usually anchored with each other or the matrix for communication, strength, and transfer

Tight junction

A zipper-like, interlocking linkage between cells by trans membrane adhesion proteins

Desmosome

A Velcro-like patch that holds cells together and resists mechanical stress, has hook-shaped proteins with more space in between

Hemidesmosome

A half-desmosome that anchors basal cells of an epithelium to the basement membrane

Gap junction

Junction formed by orange-like connexons, these transfer substances like a bridge and are located in cardiac and smooth muscle as well as the embryo, lens, and cornea

Connexon

Six trrans membrane proteins arranged like segments around a water-filled pore

Gland

A cell or organ that secretes substances for use in the body or releases them

Secretion

Keeping a product useful to the body

Excretion

Removing a product not useful to the body (waste products)

Exocrine glands

Glands that maintain their contact with the surface of the epithelium via a duct

Endocrine glands

Glands that have no ducts or contact with the outside, they secrete hormones directly into the blood

Hormones

Chemical messengers that stimulate cells elsewhere in the body

Unicellular glands

Found in an epithelium that is predominantly non-secretory; can be endocrine or exocrine

Capsule

The connective tissue covering of the exocrine gland

Septa (trabeculae)

Extensions of a capsule that divide into compartments

Stroma

The connective tissue framework of the gland; supports and organizes glandular tissue

Parenchyma

Cells that perform both the tasks of synthesis and secretion

Classification of glands

By duct (simple and unbranched, or compound and branched) or by gland shape (tubular with narrow secretory portion, acinar with multiple secretory cells, or tubuloacinar with both characteristics)

Serous glands

Produce thin, watery secretions (perspiration, milk, tears, digestive juices)

Mucous glands

Produce glocyoprotin, mucin, to absorb water from mucous

Mixed glands

Contain both serous and mucous cell types and produces a mixture

Eccrine glands

Uses vesicles that release secretion by exocytosis, like tears, the pancreas, etc

Apocrine glands

A liquid droplet covered by the membrane and cytoplasm from the cell surface; used to make milk

Holocrine secretion

Cells accumulate a product until they disintegrate, secretes cell fragments and substances

Membranes

Only epithelial, only connective or a mix of epithelial, connective, and muscular tissues

Cutaneous membrane

The skin (the largest membrane in the body), made up of stratified squamous epithelium on connective tissue

Mucous membrane

Lines passages that open to the external environment (like the digestive tract); absorbs, secretes, and protects often with goblet cells

Serous membrane

Internal membranes of simple squamous epithelium on areolar tissue; produces serous fluid that arises from blood and lines organs and body cavities (endothelium to the heart, mesothelium on cavities)

Excitability

The ability to respond to stimuli by changing membrane potential; most developed in nervous and muscular tissues

Membrane potential

The electrical difference in voltage that occurs across the cell membrane; neurons transmit signals while muscles contract

Nervous tissue

Tissue specialized for communication by electrical and chemical signals

Neurons (nerve cells)

Cells in nervous tissue that detect stimuli, respond quickly, and transmit coded information

Neuroglia (glial cells)

Cells in the nervous tissue that protect and assist the neurons

Neurosoma

The cell body of the neuron; it houses the nucleus and controls protein synthesis

Dendrites

Short, branched processes that receive signals from other cells and transmit messages to the neurosoma

Axon (nerve fibers)

Sends outgoing signals to other cells and can be more than a meter long

Muscular tissue

Elongated cells that are specialized to contract in response to stimulation; made to exert physical force on tissues, move the body, and create body heat

Types of muscular tissue

1. Skeletal

2. Cardiac

3. Smooth

Skeletal muscle

Type of muscular tissue made up of long, thin muscle fibers that attach to bone, contrains multiple nuclei and striations and are voluntarily controlled

Striations

Alternating dark and light bands

Cardiac muscle

Type of involuntary muscular tissue that is limited to the heart wall; they are short and branched with a centrally located nucleus, intercalated discs that provide electrical connection

Smooth muscle

Type of involuntary muscular tissue usually found in the stomach, it lacks striations, is short, and has one central nucleus

Epithelia

Sheets of closely adhering cells that cover body surfaces and life body cavities; they have a high rate of mitosis

Avascularity

Lacking blood vessels; epithelia have this quality and are nourished by underlying connective tissue

Functions of epithelia

• Protect deeper tissues from injury and infection

• Produce and release chemical secretions

• Excrete wastes

• Absorb and filter substances

• Sense stimuli

Basement membrane

The layer between epithelium and the underlying connective tissues; comprised of collagen and glycorproteins to anchor it down

Basal surface

Cell surface facing the basement membrane; the bottom

Apical surface

Cell surface that faces away from the basement membrane; the top

Lateral surface

Cell surface between the basal and apical surface; the sidewall

Simple epithelia

Contains one layer of cells and are named by their shape; all touching the basement membrane

Stratified epithelia

Contains many layers of cells are named by their topmost (apical) shape; some may not touch the basement membrane and can rest on others

Pseudostratified columnar epithelia

Epithelia that may appear to be stratified but only differentiated by height of cells—located in the respiratory tract, sex cells, and male urethra, as it secretes and propels mucus

Squamous epithelia

Cells that are thin and scaly, flattened

Cuboidal epithelia

Epithelia that are cube-shaped, square, or round

Columnar epithelia

Epithelia that are tall or narrow, shaped like columns

Goblet cells

Wineglass-shaped mucus-secreting cells in simple columnar and pseudostratified epithelia

Simple squamous epithelium

A single row of thin cells with nuclei near the basement membrane; they permit rapid diffusion or transport of substances and secrete serous fluid—located in the alveoli (air sacs), capillaries, and endothelium

Simple cuboidal epithelium

A single layer of square or round cells; they absorb and secrete substances and aid mucus production and movement—located in the liver, thyroid, salivary glands, and kidney tubules

Simple columnar epithelium

A single row of tall, narrow cells; they are in the border of microvilli and aid in absorption and secretion of mucus—located in the GI tract as part of cilia and lining for absorption

Stratified squamous epithelium

The most widespread epithelium in the body; the deepest layers undergo continuous mitosis as cells are pushed up and die or flake off—lines oral cavity and anal canal

Keratinized stratified squamous epithelium

Multiple cell layers, the cells become flat and scaly toward the surface; protects from outside by resisting abrasion, preventing water loss, and penetration by organisms—located in epidermis, palms, and soles

Nonkeratinized stratified squamous epithelium

Same as keratinzed epithelium without surface layer of dead cells, also resists abrasion and penetration—located on tongue, esophagus

Stratified cuboidal epithelium

Two or more layers of square or round surface cells; secretes sweat, produces sperm, and hormones in sweat glands and reproductive organs

Urothelium (transitional epithelium)

Multilayered epithelium that can stretch between round and flat; located in ureter and bladder for filling of urinary tract

Connective tissue

Abundant type of tissue where cells may not be in direct contact; supports, connects, and protects organs with varying avascularity

Functions of connective tissue

• Connecting organs

• Support and movement

• Physical and immune protection

• Heat production

• Internal transport and storage

Fibrous connective tissue

Connective tissue made up of many types of cells; types include loose, dense regular/irregular, areolar, and reticular

Fibroblasts

Fibers in fibrous connective tissue; the ground substance of the matrix

Macrophages

Cells in fibrous connective tissue that phagocytize (eat) foreign material and activate immune system

Leukocytes

White blood cells in fibrous connective tissue; made of up neutrophils and lymphocytes (anti-bacteria, toxins, and foreign agents)

Mast cells

Cells in fibrous connective tissue that secrete substances to inhibit blood clotting and dilate blood cells

Adipocytes

Cells in fibrous connective tissue that store triglycerides, or fat molecules

Collagenous fiber

A fiber in fibrous connective tissue; makes up 25% of the body’s proteins and is tough, flexible, and stretch-resistant to make up tendons, ligaments, and deep skin layers

Reticular fiber

A fiber in fibrous connective tissue; made up of collagen fibers coated with glycoprotein to make up spleen and lymph nodes

Elastic fiber

A fiber in fibrous connective tissue; made up of elastin to allow stretching and recoiling particularly in elastic cartilage in external ears

Proteoglycans

Part of ground substance in fibrous connective tissue made of brush-shaped molecules; holds tissues together with gravy-like colloids

Adhesive glycoproteins

Part of ground substance in fibrous connective tissue made of protein-carbohydrate complexes; binds tissue components

Loose connective tissue

Fibrous connective tissue with gel-like ground substance between cells; includes areolar and reticular loose tissue