Lecture Exam #2 Flashcards
What are the general characteristics and functions of epithelial tissue?
- Closely packed cells
- Specialized junctions between cells (desmosomes/tight juctions)
- Apical-basal polarity (distinct surfaces)
- Mitotic (high regeneration capacity)
- Avascular (lacks blood vessels) but innervated (supplied by nerve fibers)
- Supported by underlying connective tissue (basement membrane)
Main job is coverage/protection
Tight Junctions
Impermeable junctions that dorm continuous seals around the cells prevent molecules from passing through the intercellular space.
Desmosomes
Anchoring Junctions that bind adjacent cells together and act like molecular “velcro” and also help form an internal tension-reducing network of fibers.
How is epithelial tissue classified?
Number of Cell Layers (Simple vs. Stratified)
and Cell Type (Squamous, cubiodal, and columnar)
What are the different types of epithelial tissue?
Squamous, Cuboidal, and Columnar Epithelial
Transitional Epithelium
Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shape or squamouslike, depending on degree or origin.
Function: Stretches readily and permits distension of urinary organ by contained urine.
Location: Lines the ureters, urinary bladder, and part of the urethra.
Stratified Squamous Epithelium
Description: Thick membrane composed of several layers; basal cells are cuboidal or columnar and metabolically active.
Functions: Protects underlying tissues in areas subjected to abrasion.
Location: non keratinized type forms the lining of the esophagus, mouth and vagina. Keratinized forms the epidermis of the skin, a dry membrane.
Pseudostratified Columnar Epithelium
Description: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting goblet cells and bear cilia.
Functions: secretes substances, particularly mucus; propulsion of mucus by ciliary action.
Location: Ducts of large glands; ciliated versions in upper respiratory tract.
Simple Columnar Epithelium
Description: Single Layer of Tall Cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands
Functions: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus by ciliary action.
Location: Nonciliated type lines most of the digestive tract, gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.
Simple Cuboidal
Description: Single layer of cubelike cells with large, spherical central nuclei
Function: Secretion and Absorption
Location: Kidney Tubules; ducts and secretory portions of small glands; ovary surface
Simple Squamous Epithelium
Description: Single layer of flattened cells (Simplest Epithelia)
Function: Allows Materials to pass by diffusion and filtration in sites where protection is not important.
Location: Kidney, air sacs of lungs, lining of the heart, blood vessels, etc.
Reticular CT
Description: Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network.
Function: Fibers form a soft internal skeleton that supports other cell types, including white blood cells, mast cells, and macrophages.
Location: Lymphoid organs (lymph nodes, bone marrow, and spleen)
Dense Regular CT
Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast.
Function: Attaches muscles to bones or to other muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction
Location: Tendons, most ligaments
Elastic CT
Description: Dense Regular CT containing a high proportion of elastic fibers
Function: Allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration
Location: Walls of large arteries, within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes.
Dense Irregular CT
Description: Primarily irregularly arranged collagen fibers; some elastic fibers, major cell type is the fibroblast.
Function: Able to withstand tension exerted in many different directions; provides structural strength.
Location: Fibrous capsules of organs and joints; dermis of the skin; submucosa of digestive tract.
Adipose CT
Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushes to the side by large fat droplet.
Function: Provides reserve fuel; insulates against heat loss; supports and protects organs.
Location: Under skin, around kidneys and eyeballs; within abdomen; in breasts
Areolar CT
Description: Gel-like matrix with all three fiber types; cells; fibroblasts, macrophages, mast cells, and some white blood cells.
Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays a role in inflammation; holds and conveys tissue fluid
Location: Under epithelia of body
What are glands composed of?
Glands are composed of epithelial tissue.
Definition: one or more cells which secrete a product
The product is usually an aqueous fluid containing proteins.
Some glands produce a lipid-rich secretion.
What does the basement membrane consist of?
What is the difference between endocrine and exocrine glands?
Endocrine glands: (internally secreting) secrete their product into the surrounding interstitial fluid. They lose their ducts during development. They secrete hormones into the interstitial fluid. These hormones then enter the blood. Ex. Thyroid, gonads, pituitary, part of the pancreas.
Exocrine glands: (externally secreting) secrete their product to the surface of the epithelium. They retain the connecting cells, which form a duct that transports secretions to the epithelial surface. Ex. Sweat, oil, salivary, liver, part of pancreas.
What are the two types of Exocrine Glands
Unicellular (Goblet cells)
Multicellular (Many cells secreting into a duct) (Complex structures)
What is the difference between holocrine and merocrine secretion? Include examples of each;)
Merocrine secretion: Exocytosis. Ex. Sweat, salivary, pancreas.
Holocrine Secretion: Cell ruptures, releases secretions and dead cell fragments. Ex. Sebaceous (oil)
What are the general characteristics of connective tissue and its functions?
Functions: protection, insulation, binding, and support/framework. There are four types of CT:
Connective tissue proper, Cartilage, Bone, and Blood.
Characteristics:
1. CT arises from the same embryonic tissue called mesenchyme (middle layer of cells in embryonic development)
2. CT has variable vascularity (some lack blood vessels - avascular, and some have blood vessels - vascular)
3. Composed of resident cells embedded in a extracellular matrix (ECM)
What are the 4 common characteristics of connective tissue?
Extracellular matrix, common origin, variable vascularity
What are the types of fibers found in connective tissues and what are their functions?
There are three types of fibrous proteins: (1) collagen, (2) elastic, and (3) reticular fibers. These fibrous proteins are surrounded by water and protein-sugar complexes to form a gel-like substance called ground substance.
Extracellular Matrix (ECM)
Composition: ground substance and fibers in which cells are scattered
- Non Cellular
- Secreted by fibroblasts in “proper” CT or resident cells in other types of CT
- Consistency varies (could be a fluid, solid, or jelly) blood=fluid, bone=solid
- Very evident except in adipose CT
Fibers
Fibrous Proteins
- Synthesized by the fibroblasts in proper CT
Collagen – strongest and functions to resist stretching or tension
Elastic – can be stretched/want to be stretched
Reticular – short fine fibers (supporting mesh that supports other cells)
What is the composition of ground substance?
Interstitial fluid containing proteins and sugars that cause it to act like “glue”
Bone Tissue
Subclasses: Compact bone and spongy bone
Cells: Osteoblasts and Osteocytes
Matrix: Gel-like ground substance calcified with inorganic salts, collagen fibers
Features: Hard tissues that resist both compression and tension, supports
Blood Slide
Cells: Red and White blood cells, Platelets
Matrix: Plasma, No fibers
Features: Fluid tissue, Functions to carry O2, CO2, Nutrients, Wastes, and other substances
Connective Tissue Proper
Subclasses: Loose connective tissue (Areolar, adipose, reticular) and dense connective tissue (regular, irregular, and reticular)
Cells: Fibroblasts, fibrocytes, defense cells, adipocytes
Matrix: Gel-like ground substance, all three fiber types (collagen, reticular, and elastic)
Features: Resists mechanical stress, nutrient storage, acts as binding tissue
Cartilage
Subclasses: Hyaline cartilage, elastic cartilage, and fibrocartilage.
Cells: Chondroblasts and chondrocytes
Matrix: Gel-like ground Substance, some have elastic and collagen fibers
Features: Cushions and supports body structures
What cells are contained within the CT
Fibroblasts → Fibrocytes
Chondroblasts → Chondrocytes
Osteoblasts → Osteocytes
Blood cells formed from hematopoietic stem cells (some exceptions, present in bone marrow)
(cells present in CT)
Blast=build (immature version of the cell
Cyte = mature version
Other cells: mast cells, adipocytes, white blood cells, macrophages
What are the different types of cells that
produce and maintain the matrix of connective tissue?
ground substance and fibrous proteins, but can vary in consistency. For example, in blood, the ECM is a fluid. In bone, the ECM is a hard, calcified matrix.
What are the three different muscle tissues?
Skeletal, Cardiac, and Smooth Muscle
Smooth Muscle
Description: Spindle-shaped cells with central nuclei; no striations; cells arranged closely to form sheets.
Function: Propels substances or a baby along internal passageways; involuntary control.
Location: Mostly in the walls of hollow organs
Cardiac Muscle
Description: branching, striated, generally uninucleate cells that interdigitate at specialized junctions called intercalated discs.
Functions: As it contracts, cardiac muscle propels blood into the circulation, involuntary control.
Location: Walls of the heart
Skeletal Muscle
Description: Long, cylindrical, multinucleate cells; obvious striations
Function: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control.
Location: In skeletal muscles attached to bones or occasionally to skin.
What are the two general cell types within nervous tissue and what are the differences between them?
Neurons: Most abundant. Sends and receives electrical impulses.
Glia: Neurological are not electrically active.
Nervous Tissue
Main component of nervous system (brain, spinal cord, nerves)
Nervous system regulates and controls body functions
What is a keratinocyte?
represent the major cell type of the epidermis, the outermost of the layers of the skin
What is the difference between sudoriferous and sebaceous glands? Location? Function?
Sebaceous or oil glands discharge a waxy oily substance called sebum into the hair follicles which lubricate the hair shaft and the skin. Sudoriferous or sweat glands are located over our entire body and consists of two types. Apocrine sweat glands and merocrine sweat glands.
What is the difference between eccrine and apocrine sudoriferous glands as to function and location?
Eccrine sweat glands occur over most of the body and open directly onto the skin’s surface. Apocrine glands open into the hair follicle, leading to the surface of the skin. Apocrine glands develop in areas with many hair follicles, such as on the scalp, armpits and groin.
Describe a 1st degree burn
only epidermis
Redness, pain, slight edema
Heals 3-5 days
Describe a 2nd degree burn
epidermis and upper dermis
Redness, pain, blisters
Heals 2-4 weeks
May not scar
Need to prevent infection
Describe a 3rd degree burn
entire thickness of skin
Nerve endings destroyed
Severe fluid loss
Scarring
Skin grafts
What are the three different types of skin cancer? Describe origin, appearance, and severity.
- Basal cell carcinoma
- Squamous cell carcinoma
- (Malignant) Melanoma
Basal Cell Carcinoma
Least malignant, most common
Stratum Basale cells proliferate and invade dermis and subcutaneous tissue
Slow growing, rarely metastasizes
Surgical excision
Squamous Cell Carcinoma
Second most common
Keratinocytes of stratum spinosum
Grow rapidly, can metastasize if not removed
Radiation or surgical removal
Melanoma
Melanocytes
Highly metastatic and resistant to chemotherapy
2-3% of skin cancers
Surgical excision and immunotherapy
ABCD characteristics of Melanoma
Asymmetry
Border irregular
Color: several
Diameter: >6 mm
Evolving
Which is the most deadly form of skin cancer?
Melanoma
What are osteocytes and what is their function?
maintaining matrix , had been osteoblasts
What are osteoclasts and what is their function?
degrades and breaks down matrix