Ch 5 Tissues Flashcards
What is a tissue?
a group of cells that are similar in structure and perform a common function
What does extracellular mean?
outside of the cell
What are the 4 major types of tissues and what are their functions?
epithelial - cover and line
connective - support and bind
nervous - control and coordinate
muscle - movement
What is histology?
the study of tissues
What is epithelial tissue?
sheet of cells that covers a body surface or lines a body cavity
How does epithelial tissue occur in the body?
covers and lines epithelium
glandular epithelium
What are some of the epithelial characteristics?
always has a free (apical) surface - exposed to outside or free internal space (lumen)
underside (basal surface) attached to connective tissue by basement membrane
avascular - no blood vessels
innervated - has nerve supply
divide readily - easy to repair/replace
tightly packed - good barrier
other functions - secretion, absorption, excretion, and sensory reception
What are the epithelial functions?
cover and line - outside on skin
secretion - spit out the good stuff
absorption
excretion - spit out the bad stuff
diffusion
What does the 2 part naming system consist of?
First name (# of cells; simple or stratified) + second name (cell shape; squamous, cuboidal, or columnar)
What is the difference between simple and stratified?
simple - single cell layer
stratified - more than one layer
What is the difference between squamous, cuboidal, and columnar?
squamous - flat
cuboidal - cube
columnar - elongated
What is simple squamous epithelium?
Appearance - single layer of thin and flat cells; looks like a fried egg from the top
Location - lining of blood vessels and air sacs (alveoli) of lungs
Function: diffusion (thin), secretion, filtration
What is simple cuboidal epithelium?
Appearance - cube - shaped cells; round nuclei
Location - the lining of kidney tubules, covers surface of ovary, lens of eye; ducts of glands
Function - secretion and absorption
What is simple columnar epithelium?
Appearance - cells are elongated, ciliated or non - ciliated, nuclei at same level, goblet cells secrete mucus
Location - in small bronchial (lungs) and uterine tubes
Function - absorption of nutrients from digested food, secretion, protects underlying tissue
What is pseudostratified columnar epithelium?
Appearance - all cells on basement membrane, but very in height; nuclei at different levels
Location - ciliated with goblet cells in upper respiratory, nonciliated in sperm and ducts of some glands
Function - secretion (mucus) and absorption
What is stratified squamous epithelium?
Appearance - several layers of cells, flat on top
Location - keratinized epidermis of the skin, water - proofing; nonkeratinized lining of mouth, vagina, esophagus and tongue
Function - protection from abrasion
What is stratified columnar epithelium?
Appearance - rare, several cell layers, basal cells cuboidal, top cells columnar
Location - small amounts in male urethra and salivary glands
Function - protection and secretion (mucus)
What is transitional epithelium?
Appearance - apical cells may be domed or squamous like depending on whether bladder is full or empty
Location - lining of urinary organs
Function - stretches
What is glandular epithelium?
Gland - one or more cells that produce and secrete substances into ducts or body fluids
What is the difference between exocrine and endocrine glands?
exocrine - secrete into ducts that open onto some internal or external surface
endocrine - secrete products into tissue fluid or blood
What are exocrine glands?
Secretions include sweat, mucus, oil, ear wax, and digestive enzymes
Examples: sweat gland and salivary glands
Unicellular (goblet cells) or multicellular (sweat gland, salivary glands)
Divided into merocrine, apocrine, and holocrine
What is merocrine?
watery product released by exocytosis
What is apocrine?
product and portion of cell pinch off; a piece of cell
What is holocrine?
entire cell with product disintegrate; whole cell
What are endocrine glands?
Ductless glands
Secretions enter the extracellular fluid and then directly diffuse into the bloodstream
Secretions are called hormones
Examples: pituitary, thyroid, adrenal
What are hormones?
they regulate many metabolic and physiological functions to maintain homeostasis
What is connective tissue?
most common tissue, amount varies by organ