Unit 1: Histology Flashcards
Histology
The study of cells and tissues.
study of tissues and how they form organs
Hist = Tissue
Ology = Study of
Tissue
Tissue
group of similar cells and cell products
Organ
Organ
composed of 2 or more tissue types (almost always connective and epithelial)
What are the Four primary tissue classes in the body?
Four primary tissue classes in the body
-Epithelial tissue
-Connective tissue
-Muscular tissue
-Nervous tissue
What Differences between tissues are be used to categorize tissue type?
Differences between tissues that can be used to categorize tissue type
-Type and function of cells
-Characteristics of the matrix (ECM)
-Amount of space occupied by cells versus matrix
Epithelial Tissue
1) One or more layers of closely adhering cells (very little ECM or stuff outside the cell)
2) Forms a flat sheet with the upper surface exposed to the environment or an internal body cavity
-one side of tissue exposed to open free space
-Avascular - depends on underlying connective tissue for oxygen (blood supply)
3) Sits on basement membrane
-thin layer of collagen and adhesive proteins
-anchors epithelium to underlying connective tissue
Notes:
-Surface of something
-sheetlike
-typically touch each other
main function = protection
basement membrane
basement membrane
-thin layer of collagen and adhesive proteins
-anchors epithelium to underlying connective tissue
epi
Upon
Two types of epithelial tissue:
1) Covering and lining epithelium
2) Glandular epithelium
Epithelial tissues is named for ___________ and __________ (of apical cells)
1) # of layers
2) shape of cells
simple = one layer
stratified = many layers
Functions of Epithelial tissue
Functions include:
-Protection
-Absorption
-Filtration
-Excretion
-Secretion
-Sensory reception
*Function related to location
Layers of Epithelium
1) Simple epithelium
-contains one layer of cells
-named for shape of cells
2) Stratified epithelium
-contains more than one layer
-named for shape of apical (surface) cells
-deepest cells (basal cells) sit on basement membrane
3) Pseudostratified
-Simple epithelium that appears stratified
Simple epithelium
Simple epithelium
-contains one layer of cells
-named for shape of cells
Stratified epithelium
Stratified epithelium
-contains more than one layer
-named for shape of apical (surface) cells
-deepest cells (basal cells) sit on basement membrane
Pseudostratified Epithelium
Pseudostratified
-Simple epithelium that appears stratified
What are the 3 Shapes of Epithelial cells
1) Squamous (flat/scale like)
-Allows rapid diffusion of substances; secretes serous fluid
2) Cuboidal (square)
-Absorption & secretion; produces mucus
3) Columnar (rectangular)
-Absorption & secretion; secretion of mucus
-Often ciliated (have little hair like structures)
Squamous Shape epithelial cell
Squamous (flat/scale like)
-Allows rapid diffusion of substances; secretes serous fluid
Cuboidal shape epithelial cell
Cuboidal (square)
-Absorption & secretion; produces mucus
Columnar shape epithelial cell
Columnar (rectangular)
-Absorption & secretion; secretion of mucus
-Often ciliated (have little hair like structures)
A single layer of cube shaped cells
simple cuboidal epithelium
Multiple layers of cells, the superficial layers are flat cells and the deep layers are cube shaped
stratified squamous epithelium
A single layer of column shaped cells (muscle)
simple columnar epithelium
A single layer of cells that appears to have multiple layers (connective)
pseudostratified epithelium
A single layer of flat cells
simple squamous
Glands are classified as _________ (even if they are not associated with __________)
-epithelial tissues
-free surfaces
Two types of glands
– Endocrine and exocrine
Glands…
…secrete substances for elimination or for use elsewhere in the body
Exocrine glands…
maintain connection to surface with a duct (tube)
Endocrine glands…
have no ducts but secrete their products (hormones) directly into bloodstream
Mucus traps
pathogens
Not unique to epithelial tissue but are most common
Intercellular junctions
What are the three types of glandular secretions?
1) Serous glands
-produce thin, watery secretions
(sweat, milk, tears and digestive juices)
2) Mucous glands
-produce a glycoprotein, mucin, that absorbs water to form a sticky secretion called mucus
3) Cytogenic glands
-release whole cells (testis and ovary)
-produce sperm and egg cells
Serous glands
Serous glands
-produce thin, watery secretions
(sweat, milk, tears and digestive juices)
Mucous glands
Mucous glands
-produce a glycoprotein, mucin, that absorbs water to form a sticky secretion called mucus
Cytogenic glands
Cytogenic glands
-release whole cells (testis and ovary)
-produce sperm and egg cells
Intercellular Junctions
All cells except blood cells are anchored to each other by intercellular junctions (or to the matrix surrounding them by adhesion proteins)
What are the types of Intercellualr Junctions?
1) Tight
2) Desmosomes (Adhesion)
3) Gap
Desmosomes
-Patch between 2 cells holding them together against mechanical stress
-CONNECT CELLS
-gap between cells is spanned by mesh of filaments
-sometimes called adhesion junction
like upholstery thread; sew cells together strong
Tight Junctions
-Encircle the cell, joining it to surrounding cells
-BARRIER
-prevents substances and bacteria from passing between cells
-close together
-not strong
-near surface of cells
-like velcro
Gap Junctions
-Transmembrane proteins form a water-filled channel
-Small solutes (metabolites and ions) pass directly from cell to cell
-CELL COMMUNICATION
aka electrical synapse
-open holes from one cell to another
-tell or give another cell something
Connective Tissue
-Consists of widely spaced cells separated by fibers and ground substance (ECM)
-Most abundant and variable tissue type
Functions:
-connects structures to each other
-gives support and protection (physical & immune)
-stores energy
-movement and transport of materials
What are the Structural Elements of connective tissue?
-Ground Substance (ECM)
-Fibers (ECM)
Cells
Ground substance and Fibers are collectively called …
the matrix (ECM = extracellular matrix)
Describe the ground substance of connective tissue.
-Gelatinous or rubbery material found in between cells
-Consists of large molecules
–proteoglycans
(Protein-carbohydrate complexes embedded in plasma membranes
create a strong bond to other cells or extracellular matrix)
–adhesive glycoproteins
(protein-carbohydrate complexes that bind plasma membrane to collagen or proteoglycans outside the cells)
describe proteoglycans
proteoglycans
(Protein-carbohydrate complexes embedded in plasma membranes
create a strong bond to other cells or extracellular matrix)
-part of ground substance of connective tissue
describe adhesive glycoproteins
adhesive glycoproteins
(protein-carbohydrate complexes that bind plasma membrane to collagen or proteoglycans outside the cells)
-part of ground substance of connective tissue
What are the three fibers of connective tissue?
1) Collagen fibers
-Made of the protein collagen
tough (stronger than steel fibers of the same diameter!)
-resistant to stretch, yet flexible
tendons, ligaments and deep layer
of the skin (dermis)
2) Reticular fibers
-thin collagen fibers coated with glycoprotein
-form framework for spleen and lymph nodes
3) Elastic fibers
-thin branching fibers made of elastin
-stretch & recoil like a rubber band (elasticity)
-give skin, lungs and arteries ability to stretch and recoil
Describe Collagen fibers
Collagen fibers
-Made of the protein collagen
tough (stronger than steel fibers of the same diameter!)
-resistant to stretch, yet flexible
tendons, ligaments and deep layer
of the skin (dermis)
Describe Reticular fibers
Reticular fibers
-thin collagen fibers coated with glycoprotein
-form framework for spleen and lymph nodes
Describe Elastic Fibers
Elastic Fibers
-thin branching fibers made of elastin
-stretch & recoil like a rubber band (elasticity)
-give skin, lungs and arteries ability to stretch and recoil
Describe the cells of connective tissue
1) Blast cells – mitotic cells that secrete ground substance and fibers for the matrix
–Fibroblasts produce protein fibers and ground substance
–Chrondroblasts – product cartilage
–Osteoblasts – form bony matrix
–Hemocytoblasts – form blood cells
*Different from other blast cells because they are not located within their own tissue (they are located in bone marrow)
2) White blood cells
3) Mast cells
-secrete heparin that inhibits clotting and histamine that dilates blood vessels
4) Adipocytes or fat cells
-store triglycerides
Blast Cells
Blast cells – mitotic cells that secrete ground substance and fibers for the matrix
Types of blast cells
–Fibroblasts produce protein fibers and ground substance
–Chrondroblasts – product cartilage
–Osteoblasts – form bony matrix
–Hemocytoblasts – form blood cells
*Different from other blast cells because they are not located within their own tissue (they are located in bone marrow)
–Fibroblasts
–Fibroblasts produce protein fibers and ground substance
–Chrondroblasts
–Chrondroblasts – product cartilage
–Osteoblasts
– form bony matrix
–Hemocytoblasts
–Hemocytoblasts
– form blood cells
*Different from other blast cells because they are not located within their own tissue (they are located in bone marrow)
White blood cells
White blood cells
Mast cells
Mast cells secrete heparin that inhibits clotting and histamine that dilates blood vessels
Adipocytes or fat cells
Adipocytes or fat cells store triglycerides
What are the classes of connective tissue?
Connective tissue proper:
–Loose
–Dense
Cartilage:
–Hyaline
–Elastic
–Fibrocartilage
Bone:
–Spongy
–Compact
Blood
Loose connective tissue
A type of connective tissue that
contains gel-like ground substance between cells
Dense connective tissue
Dense connective tissue
A type of connective tissue in which fibers fill the spaces between cells
2 types varying in fiber orientation
-dense regular connective tissue
-dense irregular connective tissue
Loose Connective tissue - Adipose Tissue
-Large, empty-looking cells with thin margins
–Nucleus pressed against cell membrane
-Energy storage, insulation, cushioning
–Subcutaneous fat beneath skin and surrounding organs
Loose Connective Tissue – Areolar Connective Tissue
-Most widely distributed connective tissue,
-Functions:
–Support – binding tissues together
–Holding body fluids (amount of fluid in areolar tissue is = to amount in blood!)
–Defend against infections
-Fibroblasts are the most common cell type
Loose Connective Tissue – Reticular tissue
Structure – reticular fibers in loose ground substance
Function – soft structure that supports other cells
Locations – bone marrow, lymph nodes, and spleen
Connective tissue - Cartilage
-Supportive connective tissue with rubbery matrix
-Chondroblasts produce cartilage
matrix, once surrounded by
cartilage → chondrocytes
-No blood vessels so diffusion must bring in nutrients and remove wastes
–injured cartilage heals slowly
-Major types of cartilage depend upon fiber types
–hyaline, fibrocartilage and elastic cartilage
Cartilage - Fibrocartilage
Cartilage containing extensive parallel collagen fibers
Resists compression and absorbs shock in some joints
Pubic symphysis and intervertebral discs
Cartilage - Hyaline
Clear, glassy matrix; fine dispersed collagen fibers; chondrocytes in small clusters enclosed in lacunae
Joints; supportive material in larynx, trachea, bronchi
Cartilage - Elastic
Similar to hyaline cartilage but contains more elastic fibers
Function: maintains the shape of a structure but allows for greater flexibility
Location: pinna/auricle of ear and epiglottis
Major types of cartilage depend upon
fiber types
Types of cartilage
1) Hyaline
2) Fibrocartilage
3) Elastic
Bone
-Spongy bone looks spongy in appearance
delicate struts of bone
fills heads of long bones
always covered by compact bone
-Compact bone looks solid in appearance
more complex arrangement
cells and matrix surrounding vertically oriented blood vessels in long bones
Spongy Bone
Spongy bone looks spongy in appearance
-delicate struts of bone
-fills heads of long bones
-always covered by compact bone
Compact Bone
Compact bone looks solid in appearance
-more complex arrangement
-cells and matrix surrounding vertically oriented blood vessels in long bones
Blood
-Variety of cells and cell fragments
(white blood cells, red blood cells, and platelets)
Found in heart and blood vessels
Muscle Tissue
-Elongated cells that are irritable (respond to stimuli) by contracting (contractile)
Function is
-to exert physical force on other tissues
-move bones
-push substances through vessels (blood, urine, food etc.)
-Pump blood
-Important source of body heat
Three types of muscle
skeletal, cardiac and smooth
Muscle tissue function
Function is
-to exert physical force on other tissues
-move bones
-push substances through vessels (blood, urine, food etc.)
-Pump blood
-Important source of body heat
3 types of muscle
Three types of muscle
-skeletal,
-cardiac
-smooth
Skeletal Muscle
-Long, cylindrical, multinucleate, un-branched, voluntary cells with striations
Movement, facial expression, posture, breathing, speech, swallowing and excretion
Cardiac
Short branched, mononucleated cells with striations and intercalated discs
Pumps blood
Smooth Muscle
-Short cells; non-striated, mononucleate
-Sheets of muscle in viscera; iris; hair follicles and sphincters
-Swallowing, GI tract functions, labor contractions, control of airflow, erection of hairs and control of pupil
Nervous tissue
-Large neurons with long cell processes surrounded by much smaller glial cells lacking dendrites and axons
Found in brain, spinal cord, nerves & ganglia
Communication and control of bodily functions
Mucous Membranes
-Consists of epithelium, connective and underlying muscular tissues
-Lines passageways that open to the exterior: digestive, respiratory, urinary and reproductive
-Mucous coating and movement of cilia trap and remove foreign particles and bacteria from internal surfaces of body
Cutaneous membrane (skin)
Cutaneous membrane (skin)
-stratified squamous epithelium resting on layer of connective tissue
relatively dry layer serves protective function
Synovial membrane
Synovial membrane lines joints (only contains connective tissue)
-secretes synovial fluid rich in hyaluronic acid into the joint
Serous membrane (serosa)
Serous membrane (serosa) – internal epithelial membrane
covers organs and walls of body cavities, produces serous fluid
Hist
tissue
Squam
Flat
Gen
create
Fibro
Fiber
Striat
stripes
Chondr
cartilage
blast
create
cardi
heart
neuro
nervous tissue or system
