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Chapter 4 - Lecture B Tissues Types of Glandular Epithelium

Not only can epithelium act as

covering for the body acting as epidermis but it can also

act as the glandular epithelium

and so we're going to spend a few minutes here talking about what a gland is and

the different types of

glands first of all a gland

is one or more cells that makes or

secretes a particular product

so it's responsible for secretion

usually of a fluid that contains proteins or variation of this

glandular cells are going to be secreting a substance either onto

the surface or into the bloodstream and so

these types of glands are either

endocrine or exocrine and

endocrine means within so internally secreting so

it secretes a substance into the bloodstream

or the the fluid itself the extracellular fluid

so when we think of the endocrine system this would be an example

the thyroid gland would have endothelial or

or epithelial cells making up the gland we also have

exocrine glands which

involves secreting something outside of the body externally secreting

onto the surface now

these glands are also named by the numbers of cells that they have

so either they have one cell and if they have one cell

then they're called unicellular or if they have multiple cells

then they would be multicellular

so

endocrine means ductless

and it's a gland that's going to produce hormones so

hormones that enter into the blood or the lymphatic

fluid so the blood

or the lymphatic fluid would be an example

endocrine

glands there's many different examples of them

but there's going to be the secretions are going to include

amino acids, proteins,

glycoproteins or steroids and you'll learn a lot more about these next semester in

Anatomy & Physiology 2

exocrine glands are much more numerous

and they're going to be secreting a product onto the body surface

so into the skin and

also other body cavities and the unicellular ones

are going to be secreting their product via

exocytosis which you learned about

back in chapter 3 other examples of exocrine glands

are going to be the multi cellular exocrine glands

and they would be things that would secrete

mucus so there would be mucous glands

there would be sweat glands, oil glands,

salivary glands and even the liver and some

digestive organs like the pancreas for example

would be another example so the pancreas is an interesting

organ because not only is it endocrine

endocrine the pancreas is going to

release the hormone insulin and there's another hormone called

glucagon but again it's secreted directly into the blood so by definition it's

considered

endocrine but it's also considered exocrine too because it actually

secretes

some digestive enzymes into the GI tract

so as long as it goes into the GI tract which is exposed to

the external part of our body that's considered exocrine

now our next slide is showing figure 4.4 that you have

in your textbook and this is an example of

a unicellular exocrine gland so keep in mind that the majority of them

are multicellular but this is an example of

a unicellular one and this would be

called a mucous cell

mucous cells are examples

and this is this one in this case though would be a Goblet cell

Goblet cells are very important in the body

and they're primarily going to be found in the epithelial linings

of the intestinal tract

and also the respiratory tract so in the previous mini lecture

you saw examples of Goblet cells

in the pseudostratified epithelial cells

so in this Goblet cell on the screen you see

there's accumulation of mucin

which is then going to be secreted

via exocytosis so these are found a lot of times between

epithelial cells so in this case

where the arrows pointing to this would be an epithelial cell

our next slide is showing a chart which is

in your textbook as well and you need to be familiar with these different

examples and where they're found these are multi cellular

exocrine glands and they can be

first about classified by how many

cells there are so they're designed they can either be simple glands

and have been unbranched duct

as we see an example here so the intestinal gland would be an example

of a simple tubular one

there could also be a simple alveolar one which is not really that important

in humans

but alveolar means small flask-like sacs

then there could be some more complicated ones too but the other

simple one you should know is the stomach or gastric glands

these are simple branched tubular and there's also simple

branched alveolar which would be the sebaceous or the oil gland

and you'll be learning about this in the next unit for chapter five

then some of the more complicated ones are the compound tubular

which is in the duodenal glands of the small intestine

this is the first part of the small intestine

and then the compound alveolar ones would be things like the mammary glands

and the compound tubuloalveolar one of the more complex ones

would be the salivary glands where saliva

would be secreted from as an exocrine gland

these exocrine glands are also named by the mode

of secretion and there are three different ones that you should be familiar

with

first of all there's the merocine which secretes the

products by exocytosis as they are produced

and again you learned about exocytosis in

chapter 3

and so the example here would be the pancreas,

the sweat glands as well as

the salivary glands now I want to point out one thing here to you

notice on this previous slide that the sebaceous glands

are oil glands so the

the sweat glands would actually be producing

a watery solution so this would be the saltwater solution

that we're commonly

used to for sweating so a saltwater solution would be the

sweat but the sebaceous glands would be the oil

glands notice that oil glands are an example

a holocrine secretion and in this case there is a

rupture of the gland cells themselves

so in this case it's almost like the whole or the entire

solution that is synthesized is going to be

released at once and so dead cells fragments are secreted

with the sebaceous glands as the holocrine example

and so on the right side of your slide

you see holocrine so the entire dead cell fragments are going to be

secreted at once where as on the left side

you see an example of merocrine