Chapter 5 - Histology

Three of the stratified epithelia are named for he shapes of their surface cells: - stratified squamous - stratified cuboidal - stratified columnar

**The deeper cells, however, may be of a different shape than the surface cells.

Why is blood considered a connective tissue?

- Blood is composed of more ground substance than cells: its ground substance is the blood plasma; its cells are collectively called formed elements (erythrocytes, leukocytes, platelets) - Blood is produced by the connective tissues of the bone marrow and lymphatic organs

What are the 3 primary germ layers of the embryo? What are some adults cells that derive from them?

- Ectoderm >> epidermis and nervous system. - Mesoderm >> mesenchyme >> cardiac muscle, bone, blood, and other tissues. - Endoderm >> mucous membranes of the digestive and respiratory tracts and digestive glands.

What are functions of gap junctions?

- allow small substances (such as ions, glucose, amino acid) to pass directly from cytoplasm of one cell to another - allow nutrients to pass throughout the embryo until the circulatory system forms and takes over the role of nutrient distribution - allow nutrients to pass from cell to cell in some organs that lack blood vessels (such as lens and cornea) - allow electrical excitation to pass directly from cell to cell

Functions of the basement membrane

- anchors the epithelial tissue to its underlying tissue - controls the passage of material into and out of the epithelial tissue - binds with growth factors from below to regulate development of the epithelial tissue.

What are functions of adhesive glycoproteins?

- bind plasma membrane protein to extracellular collagen and proteoglycans - bind the components of a tissue together - mark paths to guide the migrating embryonic cells to their destinations in a tissue

What are functions of the proteoglycan?

- slows the spread of pathogenic organisms through the tissues - creates a strong bond between cells and extracellular macromolecules - helps to hold tissues together

What is a proteoglycan composed of?

A central core of protein and outgrowths of glycosaminoglycans.

What is apocrine gland? Give some examples.

A gland that releases droplets of lipid coalesced in cytosol that bud from the cell surface. Ex. Secreting milk fat from the mammary glands

What is merocrine or eccrine gland? Give some examples.

A gland that releases its products by means of exocytosis. Ex: tear glands, salivary glands, sweat glands, pancreas and other glands

Give a difference between a secretion and an excretion.

A secretion is a useful product to the body such as enzyme or hormone. An excretion is a waste product such as urine.

What are striations of the muscle cell?

Alternating light and dark bands, created by the overlapping pattern of cytoplasmic protein filaments that cause muscle contraction.

Types of loose connective tissue include?

Areolar tissue and reticular tissue

What occupies the space between adipocytes?

Areolar tissue, reticular tissue, and blood capillaries

Why would desmosomes not be suitable as the sole intercellular junctions between the epithelial cells lining the inside of the stomach?

Because desmosomes make stomach hard to stretch and contract in its digestive function, furthermore desmosomes cannot prevent substances from passing between tissue, making digestive juices seep between epithelial cells and digest the underlying connective tissue.

Why are injured tendons and ligaments slow to heal?

Because tendons and ligaments are dense regular connective tissue, which have few blood vessels.

Why is transitional epithelium suitable for urinary tract?

Because the surface cells of transitional epithelia are dome-shaped, and so are called umbrella cells. Also, their cell membranes have denser phospholipids than usual and lipid rafts embedded by the protein uroplakins, which are impermeable to urine.

Why are cartilage tissues slow to heal after an injury?

Because they do not have their own blood supply and nutrition and waste removal depend on solute diffusion through the stiff matrix, so they have low rates of metabolism and cell division.

In general, why do women have more fat relative to body weight than men do?

Because this helps women meet enough caloric needs during pregnancy and nursing, and having too little fat reduces female fertility.

What are some functions of the connective tissue?

Binding of organs Support Physical protection Immune defense Movement Storage of energy Production of heat Transport

What cells turn into plasma cells? What do plasma cells produce?

Certain lymphocytes turn into plasma cells, which produce antibodies when they detect foreign objects.

Common GAGs include chondroitin sulfate, heparin, and hyaluronic acid. What are functions of each of the aforementioned substances?

Chondroitin sulfate - gives cartilage its stiffness Heparin - inhibits blood clotting (anticoagulant) Hyaluronic acid - lubricates the joints and constitutes the vitreous body of eye ball

About one-third of the dry weight of bone is composed of [...] and [...], which enable bone to bend slightly under stress. The rest two-thirds consists of [...] (mainly [...] and [...]) that enable bones to withstand compression by the body weight.

Collagen fibers Glycosaminoglycans Minerals Calcium Phosphate salts

What are 3 types of fibers found in the fibrous connective tissues?

Collagenous fibers Reticular fibers Elastic fibers

Among the 4 primary categories of tissues, which one is the most abundant in human body?

Connective tissue

What is the largest membrane of the body? What tissue is it composed of?

Cutaneous membrane — stratified squamous epithelium

Types of dense connective tissues include?

Dense regular and dense irregular connective tissues

Give some functions of desmosomes and hemidesmosomes.

Desmosomes: - Keep cells from pulling apart - Help cells resist to mechanical stress Hemidesmosomes: anchor epithelial tissue to the underlying connective tissue

What is glycosaminoglycan (GAG) composed of?

Disaccharides (amino sugars) and uronic acid

What are some functions of cell junctions?

Enable cells to resist stress, communicate with each other, and control movement of substances through tissues

Classify each of the following into one of the four primary tissue classes: the skin surface, fat, the spinal cord, most heart tissue, bone, tendons, blood, and the inner lining of the stomach.

Epithelial tissue: the skin surface, the inner lining of the stomach Connective tissue: fat, bone, tendons, blood Nervous tissue: the spinal cord Muscular tissue: most heart tissue.

What are the 4 primary tissue classes.

Epithelial, connective, nervous, and muscle tissues.

Mucous membrane (mucosa) consists of 2 - 3 layers such as?

Epithelium Lamina propria (an areolar connective tissue layer) Muscularis mucosae (a smooth muscle layer)

______ consists of a sheet of closely adhering cells, one or more cells thick, with the upper surface usually exposed to the environment or to an internal space in the body.

Epithelium tissue

_______ = The study of exfoliated cells.

Exfoliate cytology

_______ or _______ is when epithelial cells migrate toward the surface and flake off because of actively-mitotic daughter cells of the deeper layers.

Exfoliation or desquamation

How are glands classified according to their structures?

Exocrine glands (remain in contact with body surface and internal lumen through ducts, secrete their products through ducts to the surface) Endocrine glands (lose contact with the surface, and secrete their products directly into the bloodstream)

________ is composed of fibrous proteins and a clear gel variously known as ground substance, tissue fluid, extracellular fluid (ECF), or interstitial fluid.

Extracellular matrix or material (ECM)

What do fibroblasts produce?

Fibers and ground substance that form the matrix of the tissues

List the 6 types of cells of fibroconnective tissue.

Fibroblasts Macrophages Leukocytes or white blood cells (WBCs) Plasma cells Mast cells Adipocytes

4 broad categories of mature connective tissues?

Fibrous connective tissue, adipose tissue, supportive connective tissue (bone, cartilage), and fluid connective tissue (blood)

3 types of large molecules that are consisted by ground substance?

Glycosaminoglycans, proteoglycans, and adhesive glycoproteins

What do mast cells secrete? What does each substance do?

Heparin - inhibits blood clotting Histamine - increases blood flow by dilating blood vessels.

_______ = A thin, stained slice of tissue mounted on a microscope slide.

Histological section/Tissue section

_______ or _______ = The study of tissues and how they are arranged into organs.

Histology Microscopic anatomy

How does brown fat get its color?

It is abundant of blood vessels and certain enzymes in its mitochondria.

Types of fibrous connective tissue include?

Loose and dense connective tissues

What is Marfan syndrome? What are its clinical signs? What are its serious problems or complications?

Marfan syndrome is a heredity defect in elastic fibers, resulting from a mutation in a gene for fibrillin. Clinical signs: hyperextensible joints, hernias of the groin, visual problems, tall stature, long limbs, spidery fingers, abnormal spinal curvature and a protruding "pigeon breast". Serious problems: weakened heart valves and arterial walls (aortic aneurysm and aortic rupture)

How are glands classified according to their methods of secretion?

Merocrine or eccrine glands Apocrine glands Holocrine glands

What embryonic germ layer gives rise to nervous tissue? To the liver? To muscle?

Nervous tissue << ectoderm Liver << endoderm Muscle << mesoderm (mesenchyme)

What causes pemphigus vulgaris? What are its consequences?

Pemphigus vulgaris is a condition when misguided antibodies (autoantibodies) attack the desmosomes proteins, breaking down the desmosomes, especially in skin and mucous membranes. Leading consequences include widespread of skin and oral mucosa, loss of tissue fluid, and death sometimes.

Functions of epithelial tissue

Protection (skin) Secretion (glands>>mucus, sweat, hormones, enzymes, etc.) Excretion (lung>>CO2, liver>>bile) Absorption (small intestine<< nutrition) Filtration (kidneys) Sensation (nerve endings of the skin, stomach, etc.)

What are representative locations and functions of cardiac muscle tissue?

Representative location: Heart Functions: Pumping of blood; under involuntary control

What are representative locations and functions of osseous tissue?

Representative location: Skeleton Functions: physical supports of body; leverage for muscle action; protection of viscera; reservoir of calcium and phosphorus

What are representative locations and functions of areolar tissue?

Representative locations: Underlying nearly all epithelia; surrounding blood vessels and nerves, esophagus, trachea; fascia between muscles; mesenteries; visceral layers of pericardium and pleura. Functions: binds epithelia to deeper tissues; provides paths for blood vessels and nerves to travel through tissues; provides an arena for immune defense

Simple squamous epithelium

Representative locations: alveoli; glomerular capsules; some kidney tubules; endothelium of heart and blood vessels; serosa of stomach, intestines, and some other viscera; mesothelium of peritoneum, pericardium, pleura, and mesenteries. Functions: - facilitates the diffusion and transport of substances between membranes - secretes lubricating serous fluid.

What are representative locations and functions of hyaline cartilage?

Representative locations: articular cartilage over the ends of bones at movable joints; supportive rings around trachea and bronchi; enclosure around the larynx; much of the fetal skeleton; and a costal cartilage that attaches the end of a rib to the breastbone, Functions: eases joint movements; holds larynx open during respiration; moves vocal cords during speaking; a precursor of bone in the fetal skeleton and the growth zones of long bones of children

What are representative locations and functions of neuron and glial cells?

Representative locations: brain, spinal cord, nerves, ganglia Function: Internal communication

What are representative locations and functions of the blood?

Representative locations: contained in heart and blood vessels Functions: transports gases, nutrients, wastes, chemical signals, and heat throughout the body; provides immune defense (leukocytes); minimizes bleeding (clotting agents); secretes growth factors that promote tissue maintenance and repair (platelets)

What are representative locations and functions of dense irregular connective tissue?

Representative locations: dermis; capsules around viscera such as liver, spleen, kidney; fibrous sheaths around cartilages and bones Function: withstands stresses applied in unpredictable directions

Keratinized stratified squamous epithelium

Representative locations: epidermis (palms and soles, especially) Functions: - resists abrasion, prevents penetration of pathogenic organisms - retards water loss through skin.

What are representative locations and functions of elastic cartilage?

Representative locations: external ear and epiglottis Functions: provides elastic, flexible support

What are representative locations and functions of reticular tissue?

Representative locations: lymph nodes, thymus, bone marrow, spleen Function: forms a supportive stroma (framework) for lymphatic organs

Simple cuboidal epithelium

Representative locations: most kidney tubules; bronchioles; liver; thyroid; mammary, salivary, and other glands Functions: - absorbs and secretes substances - produces protective mucous coat - moves the respiratory mucus.

Transitional epithelium

Representative locations: part of kidney, ureter, bladder, and part of urethra Functions: allows stretching of the urinary tract and protects the underlying tissues from osmotic damage of the urine.

What are representative locations and functions of fibrocartilage?

Representative locations: pubic symphysis; intervertebral discs; menisci; at where tendons insert on bones near articular hyaline cartilage Functions: resists compression and absorbs shock

Ciliated pseudostratified columnar epithelium

Representative locations: respiratory tract from nasal cavity to bronchi; parts of male urethra Functions: secretes and propels mucus

What are representative locations and functions of skeletal muscle tissue?

Representative locations: skeletal muscles (mostly attached to bones), tongue, esophagus, and encircling of the lips, eyelids, urethra, and anus Functions: body movements, facial expression, posture, breathing, speech, swallowing, control of urination and defecation, and assistance in childbirth; under voluntary control

What are representative locations and functions of adipose tissue?

Representative locations: subcutaneous fat beneath skin; breast; heart surface; mesenteries; surrounding organs such as kidneys and eyes Functions: provides thermal insulation, anchors and cushions organs; energy storage; fills space; shapes body; and produces heat (by brown fat)

Stratified cuboidal epithelium

Representative locations: sweat gland ducts, ovarian follicles, and seminiferous tubules Functions: contributes to sweat secretion, secretes ovarian hormones, and produces sperm.

What are representative locations and functions of dense regular connective tissue?

Representative locations: tendons and ligaments Functions: transfers muscular tension to bones (tendons) and resists stress (ligaments)

Simple columnar epithelium

Representative locations: the inner lining of stomach and intestines; gallbladder; uterus and uterine tubes; some kidney tubules Functions: - absorbs and secretes mucus, bile - moves egg and embryo in the uterine tubes.

Nonkeratinized stratified squamous epithelium

Representative locations: tongue, oral mucosa, esophagus, anal canal, vagina Functions: resists abrasion and prevents penetration of pathogenic agents.

What are representative locations and functions of smooth muscle?

Representative locations: walls of blood vessels and viscera; iris; hair follicles; involuntary sphincters of urethra and anus Functions: Controls blood flow and pressure; swallowing, contractions of stomach and intestines; expulsion of feces and urine; labor contractions; control of respiratory airflow; control of pupillary diameter; erection of hairs; under involuntary controls.

What is the function of tight junctions?

Seal off the intercellular cells to prevent the movement of substances passing between cells

What is holocrine gland? Give some examples.

Secretory cells disintegrate in order to deliver their accumulated product and some cell fragments Ex. Oil producing glands of the scalp

2 principal kinds of internal membranes?

Serous and mucous membranes

How are glands classified according to their nature of secretions?

Serous glands (produce thin, watery fluids such as perspiration, milk, tears, and digestive juices) Mucous glands (produce a glycoprotein mucin, which then absorbs water to form a sticky product mucus) Mixed glands (produce a mixture of both serous and mucous secretions)

What type of epithelium is the most widespread in human body?

Stratified squamous epithelium

What is the general cellular structural pattern of a gland?

The gland is composed mostly of epithelial tissue, and usually has a supportive connective tissue framework and capsule.

There are different subtypes of connective tissues, point out one thing that they share in common.

Their cells occupy less space than the extracellular matrix.

What means do nervous and muscular tissues respond to outside stimuli? What are the respective results?

They respond to the outside stimuli by means of changes in membrane potential. **Results: - Nervous tissue results in rapid transmission of signals to other cells. - Muscle tissue results in contraction or shortening of the cells

_______ = A group of similar cells and cell products that arise from the same region of the embryo and work together to perform a specific structural or physiological role in an organ.

Tissue

2 kinds of fat in humans?

White (yellow) fat and brown fat

The surface of an epithelial cell that faces the basement membrane is its _______, and the one that faces away from it toward the internal cavity (lumen) of an organ is the _______.

basal surface apical surface

Between an epithelium and the underlying connective issue is a layer called the _________.

basement membrane

Tissue specimens are preserved in a _______: a chemical such as formalin that prevents decay.

fixative

Simple columnar and pseudostratified columnar epithelia often have wineglass-shaped ________ that produce protective mucous coatings over the mucous membrane.

goblet cells

Stratified squamous epithelia are of two kinds:

keratinized (cornified) and nonkeratinized

A tissue cut on its long axis is called a ________, and one cut perpendicular to this is a _______. A section cut on a slant between a longitudinal and cross section is an _______.

longitudinal section (l.s.) cross section (c.s.) oblique section

What is differentiation? Give an example.

process in which cells become specialized in structure and function. Ex: Mesenchyme to cartilage and bone.

Epithelia are classified into two broad categories:

simple squamous

3 types of muscle tissue?

skeletal, cardiac, smooth

Liquid tissues such as blood and soft tissues such as spinal cord may be prepared as _______, in which the tissue is rubbed or spread across the slide rather than sliced.

smears

Some membranes and cobwebby tissues like the areolar tissue are sometimes mounted as ______, in which the tissue is laid out on the slide.

spreads

After sectioning, the tissue specimens are then mounted on slices and artificially colored with histological ____ to enhance detail.

stains

What is neoplasia?

the development of a tumor, whether benign or malignant

What is hypertrophy? Give two examples of cells that undergo hypertrophy physiologically.

the enlargement of preexisting cells. Ex: skeletal muscle and adipocytes

What is hyperplasia? When does it occur physiologically?

tissue growth through cell multiplication. It happens during embryonic and childhood growth.