Cells and Tissues Flashcards
Name the levels of structural organization in order.
Chemical (atoms and molecules)
Cellular
Tissue (groups of similar cells)
Organ (two or more types of tissues)
Organ system (organs that work closely together)
Organismal (all the organ systems)
Describe the cell.
- the basic unit of life
- many types that differ in size, shape, and function
- all cells have some common structures and function
What are the three basic parts of a human cell?
- Plasma membrane - flexible outer boundary
- Cytoplasm - intracellular fluid containing organelles
- Nucleus - control center
Define Histology
The study of tissues
Define Tissues
a group of similar cells that work together to perform the same function
Name the 4 basic tissue types
- Nervous Tissue
- Muscle Tissue
- Epithelial Tissue
- Connective Tissue
Define Epithelial tissue and list the two types
a layer of cells that covers a body surface or lines a body cavity and serves to protect, secrete, absorb, and filter
types: covering and lining epithelium
glandular epithelium
List the 6 epithelial functions
- Protection (mechanical, chemical, infection)
e.g. skin - Absorption e.g. G.I tract
- Filtration e.g. kidney
- Excretion e.g. kidney
- Secretion e.g. glands
- Sensory Reception e.g taste buds
List the 7 special structural characteristics of epithelial tissue
- Cellularity
- Specialized contacts (desmosomes & tight junctions)
- Polarity (from basal and apical surfaces; helps move substances across surface of cell)
- Basal lamina (noncellular, underlying supportive sheet for filtering and scaffolding)
- Supported by connective tissue
- Innervated but avascular
- High regenerative capacity
How are epithelial cells classified?
- Cell Shape
- Cell Layers
What are the different epithelial cell shapes?
- Squamous cells - flat, flat nucleus
- Cuboidal cells - boxlike, round nucleus
- Columnar cells - tall, nucleus elongated
What are the different cell layers?
Simple epithelia - single layer of cells
Stratified epithelia - two or more layers of cells
NOTE: in stratified epithelia, epithelia is classified by cell shape in Apical layer (cells facing the external environ. of internal organ)
List the 4 types of Simple epithelia
- Simple squamous epithelium
- Simple cuboidal epithelium
- Simple columnar epithelium
- Pseudostratified epithelium
Simple squamous epithelium
What: a single layer of squamous epithelia
Function: allows materials to pass through diffusion and filtration
Location: kidneys, lungs, heart
Simple cuboidal epithelium
What: single layer of cuboidal epithelia
Function: secretion and absorption
Location: kidney tubules, ovary’s
Simple columnar epithelium
What: single layer of columnar epithelia
Function: absorption, and secretion of other substances
Location: digestive tract
Pseudostratified columnar epithelium
What: single layer of cells of differing heights
Function: secretion, and propulsion of mucus
Location: upper respiratory tract
List the only type of stratified epithelial tissue.
Stratified Squamous Epithelium
What: thick membrane composed of several cell layers (can be of diff. cell shapes)
Function: protects underlying tissues that are subject to abrasion
Location: mouth, esophagus
Glandular Epithelium
What: a type of epithelial tissue involved in the production and release of secretory substances
Types: Endocrine Glands
Exocrine Glands
Endocrine Glands
Function: release hormones directly into the blood
Exocrine Glands
Function: release products into ducts (mucous, sweat, oil)
Types: unicellular
multicellular
Multicellular Exocrine Glands
Classified by structure and type of secretion
Structure: Simple (unbranched ducts)
Compound glands (branched ducts)
Type of Secretion: Merocrine - most common, secretes products by exocytosis (ex. salivary glands)
Holocrine - accumulate products withing, and then rupture (*ONLY Sebaceous glands)
Apocrine - accumulates products within then apex pinches off
Define Connective Tissue
Function: Support, protect, and bind other tissues
i.e) binding/support
protection
insulation
storage
transportation
5 Types:
- Mesenchyme
- CT proper (types: loose and dense)
- Cartilage
- Bone
- Blood
Describe the structural elements of Connective tissue.
- Ground substance: interstitial fluid + cell adhesion proteins & proteoglycans (trap water)
- Fibers: collagen fibers: high tensile strength
elastic fibers: allow stretch + recoil
reticular fibers: fine network to support blood vessels and soft tissues - Cells: immature (“blast”) forms vs mature (“cyte”) forms
Others – fat cells, immune cells (WBC, mast cells, macrophages)
*NOTE: CT is living cells surrounded by matrix; details vary by tissue type
