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By the end of this section, you will be able to:
  • Explain the structure and function of epithelial tissue
  • Distinguish between tight junctions, anchoring junctions, and gap junctions
  • Distinguish between simple epithelia and stratified epithelia, as well as between squamous, cuboidal, and columnar epithelia
  • Describe the structure and function of endocrine and exocrine glands and their respective secretions

Most epithelial tissues are essentially large sheets of cells covering all the surfaces of the body exposed to the outside world and lining the outside of organs. Epithelium also forms much of the glandular tissue of the body. Skin is not the only area of the body exposed to the outside. Other areas include the airways, the digestive tract, as well as the urinary and reproductive systems, all of which are lined by an epithelium. Hollow organs and body cavities that do not connect to the exterior of the body, which includes, blood vessels and serous membranes, are lined by endothelium (plural = endothelia), which is a type of epithelium.

Epithelial cells derive from all three major embryonic layers. The epithelia lining the skin, parts of the mouth and nose, and the anus develop from the ectoderm. Cells lining the airways and most of the digestive system originate in the endoderm. The epithelium that lines vessels in the lymphatic and cardiovascular system derives from the mesoderm and is called an endothelium.

All epithelia share some important structural and functional features. This tissue is highly cellular, with little or no extracellular material present between cells. Adjoining cells form a specialized intercellular connection between their cell membranes called a cell junction    . The epithelial cells exhibit polarity with differences in structure and function between the exposed or apical    facing surface of the cell and the basal surface close to the underlying body structures. The basal lamina    , a mixture of glycoproteins and collagen, provides an attachment site for the epithelium, separating it from underlying connective tissue. The basal lamina attaches to a reticular lamina    , which is secreted by the underlying connective tissue, forming a basement membrane    that helps hold it all together.

Epithelial tissues are nearly completely avascular. For instance, no blood vessels cross the basement membrane to enter the tissue, and nutrients must come by diffusion or absorption from underlying tissues or the surface. Many epithelial tissues are capable of rapidly replacing damaged and dead cells. Sloughing off of damaged or dead cells is a characteristic of surface epithelium and allows our airways and digestive tracts to rapidly replace damaged cells with new cells.

Generalized functions of epithelial tissue

Epithelial tissues provide the body’s first line of protection from physical, chemical, and biological wear and tear. The cells of an epithelium act as gatekeepers of the body controlling permeability and allowing selective transfer of materials across a physical barrier. All substances that enter the body must cross an epithelium. Some epithelia often include structural features that allow the selective transport of molecules and ions across their cell membranes.

Questions & Answers

Its a fusion of bones where the bones becomes flexible or stiff.. Its a kind of arthritis
rumana Reply
what is ankylosis
Adam Reply
master gland Kon si h
kajal Reply
Pituitary gland
pituitary gland because it give harmonies and control other gland
glands often secrete hormones which play an important role in maintaining homeostasis.
pituitary gland
pituitary gland is master gland because it present in biran and secrtehormones and play other gland of human body and function its gland so that also called master gland.
pituitary glandis the master gland of our body
how do you study for A&P? lab and lecture?
Aubrey Reply
depends how your lab exams and lecture exams are structured. but either way, you want to study two weeks before any of the exams. study in a way that you would be teaching it to someone. lec is mostly physio. and a lil' anatomy. lab is all anatomy and motion- so memorization is key.
record the lectures in both cases. read the lessons for that class day. have questions. go to office hours. this will help you in A&P- if anything the teacher would give you a little bit of points for making so much of an effort
When one is suffering from motion sickness what area of the brain may trigger emesis?
amy Reply
that is the sign of stroke. if the patient have a stroke. the left side of body is weakness, the affected right of cerebrum but if right side of the body is weakness surely in left side!
thank you sooo much bro
Fatima Reply
Fatima hw a u
any one elaborate fr me foramens of the skull and features which they transmit
icant undrestand plz
zahruuzh Reply
try to read I hop you will understand
state and explain 20 radiology uses
what are chemicals in anatomy and physiology?
Mike Reply
what can I do to find it easy for me in anatomy and physiology course
study up on the basics of the periodic chart, learn bones and muscles attachments, and learn muscles. Those take the longest to memorize. After that it should be a little easier.
what are the two types of body cells
Jennifer Reply
what is malnutrition
malnutrition refers to faulty nutrition resulting from malabsorption,poor diet or overeating. Sometimes too these food do not contain all the six food nutrients in their right proportion.
thank you
Will u be malnourished?
What's the difference between radiology and radiology
Nothing! Radiology it means the study or using of radiation in medical science it can be 1.diagnose or treatment diagnosed radiology! x- ray. ultrasound. ct-scan. mammogram. MRI. 2. treatmen- radiation oncology, like Cobalt 60. and nuclear medicine
what is X-ray?
X-ray is type of light that make it possible to see inside any object. as human body
How the nervous system develops
ayiesher Reply
From the cells at the back of an embryo
breifly explain anatomy of thorax
Hadiza Reply
How many region the rib is divided
how many bon of human being
how to study for the skeletal system
and anatomy
I really need sources immediately
I printed out all the different bones. Put them in the see through protective sheaths and got dry erase markers. I could right on them and erase to help me learn to spell the names of markings and bones.
Or go to a book store, Barnes and Noble(doesn't have to be this) and they have coloring books for anatomy. $16. Really helpful.
okay thanks and are what study tools you use to study the materials and get a better understanding
*what are
I prefer diagrams, pictures that lay out each step with the information in each step. For Example: how action potential creates muscles to move. A pictured diagram gives me a better understanding of how each piece plays a role in each step of the process.
Also for basics, such as memorizing vocab. Flash cards are great. Don't become discouraged if you don't get them all right the first times through. The more you go through them, your brain will remember pieces of information from each and help you to pull out the information 😉
okay thanks
what is the functions of the lips in human
Momboi Reply
could I say sensation?
for protection
Lips assist in speech and eating
Too many easy questions. Which bones are the axial and appendicular? What are the abbreviations for TEE, TTE, AED, A-Mode, B-Mode, and LTH? What is the difference between hypothalamus and thalamus? Where is the parathyroid located? How many True Ribs do we have?
Sovilace Reply
Transesophageal echocardiography Transthoracic Echocardiography automated external defibrillator brightnees mode Los Hermanos Taverna
what is anatomy
okello Reply
anatomy is scientific study of body structures and how they relate to each other

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