Chapter 4 Flashcards
Histology
It is the study of tissues
4 TYPES: EPITHELIAL TISSUE MUSCLE TISSUE NEURAL TISSUE CONNECTIVE TISSUE
Epithelial tissue
It covers exposed surfaces (skin)
- It lines internal passages & chambers such as
digestive, respiratory, reproductive and urinary systems.
- It forms glands
Connective tissue
It fills internal spaces
- It provides structure and support - It transports material within the body - It stores energy
Muscle tissue
It contracts to performs movement.
- It generates heat that warms the body
Neural tissue
It carries info from one part of the body to another by
electrical impulses
Epithelial tissue includes epithelial and glands. T OR F?
T
Layers of cells that line external surfaces (skin) and internal cavities.
Glands- they are secretory structures derived from epithelia
FUNCTIONS OF EPITHELIAL TISSUE
Physical protection from - abrasion
- dehydration
- chemical or biological agents
Control permeability- Any substance that enters or leaves your body
must cross an epithelium (ions, nutrients)
Provide secretions
Exocrine cells produce secretions for physical protection
Endocrine cells produce chemical messengers in interstitial fluid, blood
Provide sensations- Receptors, Touch receptors.
- Neuroepithelium
CHARACTERISTIC OF EPITHELIA
Cellularity- the cells bound closely together by cell junctions
Polarity- Apical and Basal surfaces that face:
- the surface of the body or - internal spaces.
Attachment- a thin basement membrane
- It attaches epithelia to underlying connective tissue
Avascularity- (without blood vessels)
- It obtains nutrients by diffusion or absorption
Regeneration- by division of stem cells
EPETHELIUM IS AVASCULAR. T OR F?
T
FUNCTIONAL REGIONS OF AN EPITHELIAL CELL
- Apex
- Basolateral surfaces
NEUROEPITHELIA
Contains sensory cells that receive sensations of
- Smell - Taste - Sight - Balance or equilibrium - Hearing
SPECIALIZATIONS OF THE EPITHELIAL CELLS
Microvilli: They increase surface for absorption & secretion
(digestive & urinary tracts)
- Cilia: Move substances over the cell surface
(respiratory & reproductive tracts)
- Sterocilia: They increase surface for absorption & secretion
They are larger than microvilli
( in male reproductive tract & inner ear)
DESMOSOME
They are cell adhesion molecules & proteoglycans
They link the opposite cell membrane resisting stretching & twisting
example- superficial skin layers
Dead skin cells are shed in thin sheets because they are held together
by desmosomes.
TIGHT JUNCTION
The Lipid portion of 2 membranes
It is tight & it is interlocked together by membrane proteins
It prevents passage of water & solutes
example – the digestive tract keeps enzymes, acid & wastes
to avoid damage of tissue & stomach can not
be destroyed by HCL
SHAPE OF EPITHELIAL CELLS
Squamous- thin & flat
Cuboidal- like little hexagonal boxes
Columnar- taller & more slender