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
OF LAYERS OF EPITHELIA
Simple: single layer of cells (for absorption and secretion)
Stratified: several layers of cells (for protection)
Epithelium is connected to the underlying connective tissues by the ___
A thing basement membrane
Types of desmosomes
Spot desmosome-small discs connected to bands of intermediate filaments. The intermediate filaments function to stabilize the shape of the cell. Ties adjacent cells together
Hemidesmosome-attach a cell to extracellular structures such as protein fibers in the basement
Endocrine gland
examples: Pancreas Pituitary gland, Thyroid gland, Testes, Ovaries
Function: To regulate or coordinate the activities of other tissues, organs and systems
- are Ductless glands.
- the product is released across the cell membranes into
interstitial spaces around the cells and into capillaries
- Hormones are released into surrounding interstitial fluid & blood
Exocrine glands
examples: Pancreas, Lacrimal glands, Mammary glands, Sweat glands, salivary glands
- have Ducts
- ducts connect the glands to the surfaces
- The secretion is released onto an epithelial surface
Types of macrophages
Fixed macrophages- They expend long periods in the tissues.
-They are the front line defense
- Free macrophages – They migrate rapidly
Melanocytes
- They synthesize & store melanin (brown pigment)
- They are located at the epithelium of the skin & the eyes
- Their # differs by body regions & individuals
Mast cells
They are mobiles
- Wound healing
- Defense against pathogens
- Are found around nerves and blood vessels, skin, mucosa of mouth,
nose, conjunctiva, digestive tract, lungs.
- The cytoplasm contains granules of histamine & heparin
that are released after infection or injury - Mast cells stimulate local inflammation, play an important role in the
inflammatory process.
Lymphocytes
Derived from hematopoiesis within the bone marrow
- They migrate throughout the body
- Natural killer cells, T, B
- Against bacteria, viruses, tumors
- They increase by tissue damage & may develop into plasma cells
- The plasma cells produce antibodies against microorganisms
- Antibodies are proteins that defend the body
Connective tissue
Supports, connects or separates other tissues and organs in the body
It is found everywhere including in the Central Nervous System.
Functions
- It is an structural framework
- It transports fluid & materials
- It protects delicates organs
- It supports surrounds & interconnects tissues
- It storages energy
- It defends the body from microorganisms
Types of connective tissue
- Connective tissue proper-
Loose-fibers create loose, open framework
Dense-fibers densely placed - Fluid connective tissue-
Blood-contained in circulatory system
Lymph-contained in lymphatic system - Supporting connective tissue-
Cartilage-solid, rubbery matrix
Bone-solid, crystalline matrix
Ground substance
Fluid component of the connective tissue
It fills the space between cells & surrounds connective tissue fibers
It is clear, viscous & colorless in connective tissue proper
It is dense. Bacteria have trouble moving
Phagocytic cells can catch them easily
Ex: Plasma (is the watery ground substance in blood)
