chapter 4

what are tissues?

cells that work together to perform a function

what term is used to mean “the study of tissues"?”

Histology

what are the 4 main types of tissues in the body that makes up the organs?

Epithelial, connective, muscle, and nervous.

multiple tissues with he same function come together to form a ___

organ

what is tight junction. desmosome, and gap junction?

keep fluid from entering between cells, hold cells together, and allows chemicals to move between cells.

What are the functions of Epithelial tissues?

Protection, absorption, secretion, and permeability.

where can epithelial tissues be found?

Skin, linings of body cavities, and organs

what are the characteristics of epithelial tissues?

Epithelial tissues are characterized by closely packed cells with minimal intercellular space, polarity (having an apical and basal surface), a high rate of regeneration, and they are avascular, relying on diffusion for nutrient supply.

what does avascular mean?

no blood vessels

How do epithelial tissues get their nutrients?

they get it from diffusion from the blood vessels in the connective tissues through the basement membrane

what are basement membrane made of?

collagen and glycoproteins

what are the 3 functions of the basement membrane?

support, filtration, and guides regenration

what is regeneration?

The process by which epithelial tissues repair and replace damaged or lost cells, allowing for the restoration of tissue integrity and function.

what is keratinized?

they are found where there is the most water and tear like the skin. means that cells have become filled with a tough protein called keratin. This process makes the cells strong, hard, and protective. Keratinized tissues are tough and serve protective functions, like preventing dehydration and acting as a barrier against environmental damage.

where can keratinized be found?

In the epidermis, skin, hair, nails

what is non keratinized?

These cells are softer and more flexible, and they stay moist.

where is non-keratinized found?

found in places where protection is needed but moisture is also important, like the inside of the mouth, throat, vagina, and esophagus. These areas need to stay moist to work properly, so the cells there don't become hard like in keratinized areas.

What is cilia?

tiny, hair-like structures found on the surface of some cells. They help move substances over the surface of the cell or move the cell itself. Act like little "brooms" that sweep things along or help cells move.

what is cilia made of?

microtubules

where can cilia be found?

Respiratory Tract, Fallopian Tubes, ear, etc

what are goblet cells?

secrete mucus to protect and libricate epithelial surface. The respiratory tract, for example, mucus helps trap dirt, dust, and microbes, keeping the airways clean.

where can goblet cells be found?

Respiratory tract (lungs and airways) Digestive tract (stomach and intestines)

how do we classify epithelial tissues?

by shape and layers

what are the shapes and layers?

squamous, cuboidal, columuar, simple and stratified.

are all cells in stratified tissues the same shape?

no

how are stratified tissues made?

based on the shape of the cell at the surface

where is the simple squamous tissue free surface found?

side of the tissues that faces a body cavity, blood vessels, or air space. oppsite side of basement membrane.

what are the two specific types of simple squamous tissue?

Endothelium and Mesothelium

what is endothelium?

thin layer of specialized cells that line the interior surface of blood vessels (like arteries, veins, and capillaries) and lymphatic vessels. These cells are crucial for maintaining the health and function of the vascular system.

what is mesothelium?

is a layer of specialized cells that form the lining of certain body cavities, such as the thoracic (chest cavity), abdominal cavity, and pericardial cavity (around the heart). It produces a lubricating fluid that helps reduce friction between the organs and the walls of these cavities.

where is the free sureface of simple cuboidal tissue?

side of the tissue facing lumen (inside of a duct or gland)

which two tissues are often involve in absorption and secretion?

simple cuboidal and simple columnar

where is the free surface of the simple columnar?

side of the cell that face outward, the surface of a tissue lining an organ or cavity

what do simple columnar often line the most?

gastrointestinal tract, fallopian tubes, and larger ducts

is it true that some simple columnar can be goblet cell that product mucus?

yes

why would it be necessary that simple columnar produce mucus in the digestive tract?

the mucus protects and lubricates the digestive tract, preventing damage from stomach acids and helping food move smoothly.

what additional structures do simple columnar have on their free surface?

microvilli

why would a columnar epithelial in the digestive tract need microvilli?

to increase area helping the digestive tract absorb more nutrients efficiently

what does stratified squamous mean?

has several layers of cell and the word squamous means that the cell at the free surface are flat.

Are all cells flat in stratified squamous?

no

Where do cells often appear dense? And why?

Near the basement membrane, because that is where mitosis is occurring.

Why does mitosis occur near the basement membrane and not at the free surface?

Because this is where new cells are made. As they grow they move upward to replace old cells at the surface.

Which cells are the oldest: closet to the free surface, or those near the basement membrane?

closet to the free surface

What is keratinized stratified squamous tissue?

has a tough, protective layer of keratin (in the skin) to protect aganist wear and tear.

Where is keratinized stratified squamous tissue found?

skin, lining of mouth, esophagus, vagina, and rectum

where is stratified squamous found?

where protection is needed. the layers of cells provide a barrier to the blood vessels of the connective tissue. also salivary gland ducts

where is stratified cuboidal tissue found?

in sweat gland ducts

what is transitional?

combination of differently shaped cells that can change their shape (for stretch and recoil)

when transitional epithelium stretch or relaxed how do they appear?

stretched: stratified squamous and relaxed: stratified cuboidal columnar

where is transitional found?

lining the ureters and bladder

what does pseudostratified mean?

fake layers

where is pseudostratified found?

lining the respiratory tract and part of the male reproductive tract

does pseudostratified have cilla and goblet cells?

yes

why would that be important in the respiratory tract?

the mucus traps dirt, dust, and germs and the cilla pushes out to keep the lungs clean.

What is glandular tissue?

Glandular tissue is a type of epithelial tissue that is specialized for secretion. It forms the glands of the body, which can be further classified into exocrine (secreting substances into ducts) and endocrine (secreting hormones directly into the bloodstream).

name two similarities and two differences between an exocrine and endocrine gland.

both are made from epithelial tissue and both secrete substances important for the body like hormones or enzymes.

exocrine glands have ducts(sweat or salivary) and endorcrine do not (release hormones directly into the blood) to affect other organs.

exocrine glands release substances to an outside area (skin, digestive tract)

give and example of a unicellular gland that makes mucin

goblet cells

what does holocrine do?

the whole cell breaks apart to release its oil ex: sebaceous oil glands in the skin.

what does merocrine do?

they release their product through tiny vesicles (like packages) w/o harming the cell (ex salivary glans)

what does apocrine do?

part of the cells break off w/ the serection (ex mammary milk)

are exocrine and endocrine glands comprised of epithelial tissue?

yes