Histology Flashcards
Epithelial Tissue: General Characteristics
- Cover all body surfaces - inside & out
- Major tissue of glands
- Reproduce rapidly (thanks to vascular underlying connective tissue)
- Tightly packed
Epithelial Structure
- one side is free (exposed to outside or internal space)
- other side is attached to connective tissue by thin, nonliving layer called the basement membrane (basal lamina & reticular lamina)
Epithelial Classification
1. Simple vs. Stratified
Simple: single layer of cells
Stratified: many layers of cells
Epithelial Classification
Squamous vs. Cuboidal vs. Columnar
Squamous: thin & flat Cuboidal: cube-shaped Columnar: elongated
Simple Squamos Epithelium
Structure: single layer of thin, flat cells
Function: diffusion & filtration
Location: air sacs, walls of capillaries, inside of blood & lymph vessels
*Can Be Damaged Easily b/c so thin
Simple Cuboidal Epithelium
Structure: single layer, cube-shaped Function: secretion & absorption Location: covers ovaries, lines kidney
tubules, & gland ducts (salivary, liver, pancreas)
Simple Columnar Epithelium
Structure: single layer, elongated (column shaped) Function: absorption
Location: lining of digestive tract *microvilli
*goblet cells
Psuedostratified Columnar Epithelium
Structure: appear layered but are not
Function: trap & move foreign particles & move sex cells
Location: lines respiratory & reproductive passages
*cilia
Stratified Squamous Epithelium
Structure: outermost layer is thin, flat; deep layers cuboidal or columnar
Function:
Keratinized: dry protective coating Non-keratinized: moist & protective
Location: K = skin
Not K = esophagus, mouth, vagina
Stratified Cuboidal Epithelium
Structure: 2 layers of cubed cells Function: protection
Location: largest ducts of glands (sweat,
mammary, & salivary)
Stratified Columnar Epithelium
Structure: superficial layer elongated Function: protection
Location: male urethra, ducts of lg. glands
*rare
Transitional Epithelium
Structure: changes, squamos & cuboidal depending on stretching
Function: expandable lining & barrier
Location: ureters, urinary bladder, part of urethra
Four types of tissues
Epithelial
Connective
Muscle
Nervous
Muscle Tissue: Skeletal description
Long, cylindrical, multinucleate cells; obvious striations
Muscle Tissue: Skeletal location
In skeletal muscles attached to bones or occasionally to skin
Muscle Tissue: Skeletal function
Voluntary movement; locomotion; manipulation of the environment; facial expression, voluntary control
Muscle Tissue: Cardiac description
Branching striated, generally uninucleate cells that interdigitate at specialized junctions
Muscle Tissue: Cardiac location
The walls of the heart
Muscle Tissue: Cardiac function
As it contacts, it propels blood into the circulation; involuntary control.
Muscle Tissue: Smooth description
Spindle-shaped cells with central nuclei
Nervous Tissue description
Neurons are branching cells; cell processes that may be quite long extended from the nucleus-containing cell body; also contributing to nervous tissue are nonirritable supporting cells
Nervous Tissue function
Transmit electrical signals from sensory receptors and to effectors (muscles and glands) which control their activity
Nervous Tissue location
Brain
spinal cord
nerves
Connective Tissue
- Found everywhere in the body
- Most abundant and widely distributed tissues
Connective tissue functions
a) Binds body tissues together
b) Supports the body
c) Provides protection
Connective Tissue Characteristics
• All Types Come from Mesenchyme – – embryonic connective tissue
• Variations in blood supply
– Some well vascularized, some poor, some avascular
Connective tissue 3 Components
- Ground substance: mostly water, proteins & polysaccharides
- Fibers: Produced by FIBROBLASTS, 3 types Collagen (white) fibers, Elastic (yellow) fibers, Reticular fiber
- Cells
*1+2 = Extracellular Matrix
Mesenchyme description
Embryonic connective tissue; gel-like ground substance containing fibers; star-shaped mesenchymal cells.
Mesenchyme function
Gives rise to all other connective tissue types.
Mesenchyme location
Primarily in embryo
Areolar
Connective Tissue Proper: Loose
Areolar description
Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells and some white blood cells.
Areolar function
Wraps and cushions organs; its macrophages phagocytosis bacteria; plays important role in inflammation; holds and conveys tissue fluid
Areolar location
Widely distributed under epithelia of body, forms lamina propria of mucous membranes; packages organs, surrounds capillaries.
Adipose
Connective Tissue Proper: Loose
Adipose description
Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet.
Adipose function
Provides reserve food fuel; insulates against heat loss; supports and protects organs
Adipose location
Under skin; around kidneys and eyeballs; within abdomen; in breasts.
Reticular
Connective Tissue Proper: Loose
Reticular description
Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network.
Reticular function
Fibers from a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages
Reticular location
Lymphoid organs (lymph nodes, bone marrow, and spleen).
Dense Regular description
Primarily parallel collagen fibers; a few elastin fibers; major cell type is the fibroblast.
Dense regular function
Attaches muscles to bones or to muscles; attaches bone to bones; withstands great tensile stress when pulling force is applied in one direction
Dense regular location
Tendons, most ligaments, aponeuroses
Dense irregular description
Primarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast
