Histology Flashcards
What are the four categories of tissues
Epithelial, connective, nervous, & muscular
What is the matrix and what is it composed of
Extracellular material. Composed of fibrous proteins & ground substance
What are other terms for ground substance
Tissue fluid, extracellular fluid (ECF), interstitial fluid, or tissue gel
What form of tissues are avascular
Epithelial & cartilage
What are the 2 classifications of epithelial tissue
- Simple 2. Stratified
What are the functions of epithelial tissue
- Protect deeper tissues from injury and infection 2. Produce and release chemical secretions 3. Excrete wastes 4. Absorb chemicals including nutrients 5. Selectively filter substances 6. Sense stimuli
Difference between simple and stratified epithelia
Simple: contains one layer of cells, all cells touch the basement membrane
Stratified: contains more than one layer, sore cells rest on top of others and don’t touch the basement membrane
What are the 4 types of simple epithelia
Simple squamous, simple cuboidal, simple columnar,& pseudostratified columnar
What are the functions of simple squamous epithelium
Permits rapid diffusion or transport of substances, and secretes serous fluid
Where can you find simple squamous epithelium
Alveoli (lung), glomeruli (kidneys), endothelium,& serosa
What are the functions of simple cuboidal epithelium
Absorption and secretion, mucous production and movement
Where can you find simple cuboidal epithelium
Liver, thyroid, bronchioles, kidney tubules, mammary and salivary glands
What is the function of simple columnar epithelium
Absorption and secretion; secretion of mucous
Where can you find simple columnar epithelium
Lining of GI tract, uterus, kidney, and uterine tubes
What is the function of pseudostratified epithelium
Secretes and propels mucous
Where can you find pseudostratified epithelium
Portions of the male urethra and the respiratory tract
What makes up the respiratory tract
Nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles
How are the epithelial tissues named?
Simple: named by shape of cells
Stratified: named by shape of apical surface cells
What are the 4 types of stratified epithelia
Stratified squamous, stratified cuboidal, stratified columnar (rare type),& transitional epithelium(aka urothelia)
What is he most widespread epithelium in the body
Stratified squamous
What does the deepest layers of stratified squamous do
Undergoes continuous mitosis. Daughter cells push toward the surface becoming slather as hey migrate upward
What is it called when the stratified squamous dies and flakes off
Exfoliation or desquamation
How many kinds of stratified squamous epithelia are there, and what are they called
2, keratinized and nonkeratinized
What are the functions of keratinized stratified squamous
Resists abrasion, retards water loss through skin, resists penetration by pathogenic organisms. Use of dead cells as protection - calluses
Where can you find keratinized stratified squamous
Epidermis, palms and soles of feet (they are heavily keratinized)
What are the functions of nonkeratinized stratified squamous
Resists abrasion and penetration of pathogens (protection without dead cells)
Where can you find nonkeratinized stratified squamous
Tongue, oral mucosa, esophagus, and vagina
What are the functions of stratified cuboidal epithelium
Secretes sweat, produces sperm, produces ovarian hormones
Where can you find stratified cuboidal epithelium
Sweat gland ducts, ovarian follicles, and seminiferous tubules
Function of transitional epithelium (urothelia)
Allows for filling of urinary tract
Where can you find transitional epithelium
Ureter and bladder
Functions of connective tissues
- Binding of organs: tendons & ligaments
- Support: bones and cartilage
- Physical protection: cranium, ribs, sternum
- Immune protection: white blood cells attack foreign invaders
- Movement: bores provide lever system
- Storage: fat, calcium, phosphorus
- Heat production: metabolism of brown fat in infants
- Transport: blood
What are the cells of fibrous connective tissue
Fibroblasts, macrophages, leukocytes, plasma cells, mast cells, adipocytes
What are the fibers of fibrous connective tissue
Collagenous fibers, reticular fibers, elastic fibers
Ground substance of fibrous connective tissue
Glycosaminoglyans (GAG), proteoglycans, adhesive glycoproteins
Types of fibrous connective tissue
Loose connective, and dense connective tissues
What are the types of loose connective tissue
Areolar, reticular
What are the types of dense connective tissue
Dense regular, and dense irregular connective tissues
What are identifying characteristics of areolar tissue
Loosely organized fibers,
is abundant in blood vessels,
A lot of seemingly empty space
Where can you locate areolar tissue
Underlying epithelia
In serous membranes,
Between muscles,
Surrounding blood vessels and nerves
What is the function of areolar tissue
Loosely binds epithelia to deeper tissues,
Allows passage of nerves and blood vessels through other tissue
Provides and arena for immune defense
Blood vessels provide nutrients and waste removal for overlying epithelia
Where can you find reticular tissue
(Lymphatic organs)
Lymph nodes,
Spleen,
Thymus,
Bone marrow
What is the function of reticular tissue
Form supportive stroma (framework) for lymphoid organs
Muscle to bone
Tendons
(Muscle is meat and meat is TENDER)
Bone to bone
Ligaments
What’s the difference between dense and loose connective tissue
Dense: fiber occupies more space than the cells and ground substance
Loose: much of the space is occupied by ground substance
What are characteristics that defferentiate between regular and irregular dense connective tissue
Regular: collagen fibers are parallel, slender fibroblast nuclei compressed between collagen fibers
Irregular: collagen fibers run in random directions, few visible cells
Where can you find dense regular connective tissue
Tendons and ligaments
What are the functions of dense regular tissue
Ligaments tightly bind bones together and resist stress,
Tendons attach muscle to bone and transfer muscular tension to bones
Where can you find dense irregular connective tissue
Deeper portion of dermis of skin,
Capsules around viscera such as liver, kidney, and spleen,
Fibrous sheaths around cartilages and bones
What are the functions of dense irregular tissue
Withstanding stresses applied in unpredictable directions,
Imparts durability to tissues
What is adipose tissue
Tissue in which adipocytes are the dominant cell type
Where can you find adipose tissue
Subcutaneous fat beneath skin,
Breast,
Heart surface,
Mesenteries,
Surrounding organs such as kidneys and eyes
What are the functions of adipose tissue
Energy storage,
Thermal insulation,
Heat production by brown fat,
Protective cushion for some organs,
Filling space,
Shaping body
What is the body’s primary energy reservoir
Fat
What are the two types of adipose tissue
Brown and white
White adipose tissue(WAT), or white fat
The more abundant and the most significant adipose tissue of the ADULT body
Brown adipose tissue(BAT), or brown fat
Found mainly in fetuses, infants, and children. Adults have lesser deposits of it.
What is cartilage
A stiff connective tissue with a flexible matrix
What are chondroblasts
Cartilage cells that produce the matrix that will trap them
What are chondrocytes
Cartilage cells that are trapped in lacunae(cavities)
What is perichondrium
Sheath of dense irregular connective tissue that surrounds elastic and most hyaline cartilage (not articular cartilage)
How can you identify hyaline cartilage
Clear, glassy appearance because of fineness of collagen fibers
What is the function of hyaline cartilage
Eases joint movement, holds airway open, moves vocal cords, growth of juvenile long bones
Where can you find hyaline cartilage
Articular cartilage(joint),
Costal cartilage(rib),
Trachea(high amounts of cartilage),
Larynx,
Fetal skeleton
How can you identify elastic cartilage
Cartilage containing abundance of elastic fibers,
Covered with perichondrium
What is the function of elastic cartilage
Provides flexible, elastic support
Where can you find elastic cartilage
External ear and epiglottis
How can you identify fibrocartilage
Contains large, coarse bundles of collagen fibers
What are the functions of fibrocartilage
Resists compression and absorbs shock
Where can you find fibrocartilage
Pubic symphysis(pelvic cavity),
Menisci(knee),
Intervertebral discs(in between vertebra)
What is bone (osseous) tissue
A calcified connective tissue that composes the skeleton
Are bones organs?
Yes, since bones and organs are made of more than one tissue type
What are bones of the skeleton made of
Bone tissue,
Cartilage,
Marrow,
Other tissue types
What are the two forms of osseous tissue
Spongy bone, and compact bone
How you identify spongy bone
Has porous appearance,
Delicate struts of bone: trabeculae,
Covered by compact bone
Where can you find spongy bone
In heads of long bones and in the middle of flats bones such as the sternum
What is the appearance of compact bone
Denser, calcified tissue with no visible spaces, more complex arrangement, cells and matrix surround vertically oriented blood vessels in long bones
Where can you find compact bone
Skeleton
What is are the functions of compact bone
Physical support of body,
Leverage for muscle action,
Protective enclosure of viscera,
Reservoir of calcium and phosphorus
How is compact bone arranged
Arranged in cylinders that surround central (Haversian or osteonic) canals that run longitudinally through shafts of long bones
Where is bone matrix
Deposited in concentric lamellae
(Onion-like layers around each central canal)
What is an osteon
Central canal and it’s surrounding lamellae
What is an osteocytes
Mature bone cells within lacunae
What is canaliculi
Delicate canals radiating from each lacuna to its neighbors, allowing osteocytes to contact each other
What is periosteum
Tough fibrous connective tissue covering the whole bone
What is blood
Is a fluid connective tissue that travels through tubular blood vessels
What are the functions of blood
Transports gases, nutrients, wastes, chemical signals, and heat throughout the body,
Provides defensive leukocytes,
Contains clotting agents to minimize bleeding,
Platelets secrete growth factors that promote tissue maintenance and repair
Where is blood located
Contained in heart and blood vessels
What are erythrocytes
Red blood cells
What are leukocytes
White blood cells
Excitability is a characteristic of all living cells, but it is developed to its highest degree in nervous and muscular tissues, which are therefore described as …
Excitable tissues
What is excitability
Ability to respond to stimuli by changing membrane potential
What is membrane potential
Electrical charge difference (voltage) that occurs across the cell membrane
How does membrane potential affect nerve cells? 
Results in rapid transmission of signals to other cells
How does membrane potential affect muscle cells
Results in contraction, shortening of cell
What is nervous tissue for
It’s specialized for communication by means of electrical and chemical signals
What does nervous tissue consist of
Neurons (nerve cells),
Neuralgia (glial cells)
What are the functions of neurons
Detect stimuli,
Respond quickly,
Transmit coded information rapidly to other cells
What are the function of glial cells
Protect and assist neurons
What does nervous tissue consist more of
Glial cells
What is a neurosoma and what does it do
It is the cell body,
It houses nucleus and other organelles, and controls protein synthesis
What are dendrites
Multiple short, branched processes that receive signals from other cells, and transmits messages to neurosoma
What is an axon and what do they do
They are a nerve fiber
They send outgoing signals to other cells
(Can be more than a meter long)
What is muscular tissue
Elongated cells that are specialized to contract in response to stimulation
What are the functions of muscular tissue
Primary job is to exert physical force on other tissues and organs,
Creates movements involved in body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation,
Important source of body heat
What are the three types of muscle
Skeletal, cardiac, and smooth
What does skeletal muscle consist of
Long threadlike cells called muscle fibers,
Contains multiple nuclei adjacent to plasma membrane, striations
What are striations
Alternating dark and light bands
What does it mean for something to be voluntary
Conscious control over the something (muscular tissue)
Where are MOST skeletal muscles located
Attached to bone
Where is cardiac muscle located
Heart only
What are the functions of intercalated discs (in cardiac muscle)
They join cardiocytes end to end, and provide electrical and mechanical connection
What is smooth muscle made of
Fusiform myocytes lacking striations
Where is smooth muscle found
In walls of blood vessels,
And viscera such digestive tract (hollow organs)
(MOST IS VISCERAL MUSCLES)
What are the functions of skeletal muscle
Body movements,
Facial expression,
Posture,
Breathing,
Speech,
Swallowing,
Control of urination and defection,
And assistance in childbirth
What is the function of cardiac muscle
Pumping blood
What are the functions of smooth muscle
Swallowing,
Contractions of stomach and intestines,
Expulsion of feces and urine,
Labor contractions,
Controls blood pressure and flow,
Controls respiratory airflow,
Control of pupillary diameter,
Erection of hairs
What are the differentiating identifying characteristics of of skeletal, cardiac, and smooth muscle
Skeletal: striated and voluntary
Cardiac straiated and involuntary
Smooth: not striated and involuntary
What are cell junctions
Connections between 2 cells
What are the four types of cell junctions
Tight junctions, desmosomes, gap junction, and hemidesmosome
What are tight junctions
Linkage between two cells by transmembrane cell-adhesion proteins
What are desmosomes
Patch that holds cells together (like a clothing snap)
What is a gap junction
Also called a communicating junction, it is formed by ring like connexons
What are glands
Cell or organ that secretes substances for use elsewhere in the body or releases them for elimination from the body
What are glands usually composed of
Epithelial tissue in a connective tissue framework and capsule
What’s the difference between secretion and excretion
Secretion: product useful to the body
Excretion: waste product
What do exocrine glands do
Maintain their contact with surface of epithelium by way of a duct
(Surfaces can be external ;ex: sweat, tear glands.
Or internal; ex: pancreas, salivary glands)
What does endocrine glands do
Secrete hormones directly into the blood
They have no ducts
(Ex:thyroid, adrenal, and pituitary glands)
Can organs have both endocrine AND exocrine glands
Yes, some examples include:
Liver,
Gonads (testes and ovaries),
Pancreas
What are unicellular glands
Secretory cells found in an epithelium that is predominantly nonsecretory
(Can be exocrine or endocrine)
List examples of unicellular glands
Mucous-secreting GOBLET CELLS in trachea, or endocrine cells of stomach
What is the exocrine gland structure
Capsule, stroma, parenchyma
What is a capsule
Connective tissue covering of exocrine gland
What is a stroma
Connective tissue framework of the gland
What is a parenchyma
Cells that perform the tasks of synthesis and secretion
(Typically cuboidal or simple columnar epithelium)
What are the duct shapes
Simple (unbranched),
Compound (branched)
What are the gland shapes
Tubular: narrow secretory portion,
Acinar: secretory cells form dilated sac (acinus or alveolus)
Tubuloacinar: both tubular and acinar portions
What are the types of secretions
Serous,
Mucous,
Mixed,
Cytogenic
Define serous glands
Produce thin, watery secretions
(Perspiration, milk, tears, digestive juices)
Define mucous glands
Produce glycoprotein, mucin, which absorbs water to form mucous
(Goblet cells: unicellular mucous glands)
Define mixed glands
Contains both serous and mucous cell types and produces a mixture of the two types of secretions
Define cytogenic glands
Release whole cells
(Sperm and egg cells)
What are the modes of secretion
Merocrine,
Apocrine,
Holocrine
Define merocrine secretion
It’s used by eccrine glands, and uses vesicles that release their secretion by exocytosis
(Examples: tear glands, pancreas, gastric glands, and others)
Define apocrine secretions
Lipid droplet covered by membrane and cytoplasm buds from cell surface
(Mode of milk fat secretion by mammary gland cells)
(Apocrine is used to describe auxiliary sweat glands even though they use merocrine secretion mode)
Define holocrine secretion
Cells accumulate a product until they disintegrate
(Secrete a mixture of cell fragments and synthesized substances)
(Examples: oil glands of scalp and skin, and glands of eyelids)
What is the largest membrane in the body
Cutaneous membrane(the skin)
What tissues are membranes made of
They could be made of only epithelial,
only connective,
or even a mixture of epithelial, connective, and muscular tissues
What are the two principal kinds of internal membranes
Mucous, and serous membranes
What is a serous membrane(serosa) composed of, and what does it produce
Composes of simple squamous epithelium resting on a thin layer or areolar connective tissue.
It produces watery serous fluid that arises from blood
Define tissue growth
Increasing the number of cells or size of existing cells
Define hyperplasia
Growth through cell multiplication
(Increase number)
Define hypertrophy
Enlargement of preexisting cells
(Increase size)
(Example: muscle growth from excessive, or accumulation of body fat)
Define neoplasia
Development of a tumor(neoplasm)
(Could be benign or malignant)
(Composed of abnormal, nonfunctional tissue)
What occurs by hyperplasia
Most embryonic and childhood growth
Define metaplasia
A change from one type of mature tissue to another
Define stem cells
Undifferentiated cells that are not yet performing any specialized function
(Have potential to differentiate into one or more types of mature functional cells)
Define developmental plasticity
Ability of a stem cell to give rise to a diversity of mature cell types
What are the two types of embryonic stem cells
Totipotent, and pluripotent
Define totipotent stem cells
Have potential to develop into any type of fully differentiated human cell including accessory organs of pregnancy
Define pluripotent stem cells
Can develop into any type of cell in the embryo (but not accessory organs of pregnancy)
Define adult stem cells
Undifferentiated cells found in mature organs
What are two types of adult stem cells
Multipotent, and unipotent
Define multipotent
Able to develop into two or more cell lines
(Example: bone marrow stem cells)
Define unipotent
Produce only one cell type
(Example: cells giving rise to sperm)
What are the two ways damaged tissues can be repaired
Regeneration, and fibrosis
Define regeneration
Replacement of dead or damaged cells by the same type of cells as before
(Restores normal function)
(Example: repair of minor skin or liver injuries)
Define fibrosis
Replacement of damaged cells with scar tissue
(Scars hold organs together, but does NOT restore function)
(Examples: repair of severe cuts and burns, scarring of lungs in tuberculosis)
What is scar tissue composed of
Mainly of collagen produced by fibroblasts
Define atrophy
Shrinkage of tissue through loss of cell size or number
(Senile atrophy, from normal aging
(Disuse atrophy from lack of use)
Define necrosis
Pathological tissue death due to trauma, toxins, or infections
What are types of necrosis
Infarction, and gangrene
Define infarction
Sudden death of tissue when blood supply is cut off
Define gangrene
Tissue necrosis due to insufficient blood supply
(Usually involves infection)
Define apoptosis
Programmed cell death
(Normal death of cells that I’ve completed their function and best serve the body by dying and getting out of the way.)
tissue degeneration or death
Apoptosis,
Phagocytized by macrophages and other cells
Billions of cells die by apoptosis,
Every cell has a built in “suicide program”
Define tissue engineering
Artificial production of tissues and organs in the lab for implantation in the human body 
