Session 5.2d - Lecture 1 - Epithelial Tissues and Glands Flashcards
Slides 50 - 64
1
Q
What is stratified squamous keratinized epithelium mainly made up of?
A
Keratinocytes
2
Q
In what structure are keratinocytes the predominant cell?
A
Stratified squamous keratinised epithelium (epidermis)
3
Q
What is a keratinocyte?
A
An epidermal cell which produces keratin.
4
Q
What are the four layers of the epidermis?
A
Horny layer (stratum corneum) Granular layer (stratum granulosum) Prickle cell layer (stratum spinosum) Basal layer (stratum basale)
5
Q
What are the four layers of the epidermis by their English translation?
A
Horny layer
Granular layer
Prickle cell layer
Basal layer
6
Q
What are the four layers of the epidermis by their Latin name?
A
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
7
Q
What are the terms of the epidermis commonly used by dermatologists and pathologists?
A
Stratum corneum
Granular layer
Basal layer
8
Q
Which term is more commonly used - horny layer or stratum corneum?
A
Stratum corneum
9
Q
Which term is more commonly used - granular layer or stratum granulosum?
A
Granular layer
10
Q
Which term is more commonly used - prickle cell layer or stratum spinosum?
A
Neither is really spoken about much
11
Q
Which term is more commonly used - basal layer or stratum basale?
A
Basal layer
12
Q
What is mitosis?
A
Cell division
13
Q
What is the term for cell division?
A
Mitosis
14
Q
Where does keratinocyte mitosis occur?
A
Mainly in the BASAL LAYER
15
Q
Why is the basal layer significant?
A
(Almost all) of the keratinocyte mitosis occurs here.
16
Q
What happens to the daughter keratinocytes that are produced from mitosis?
A
They move upwards from the basal layer, differentiate, and lose their ability to divide.
17
Q
In which direction do keratinocytes move?
A
Upwards from the basal layer, after dividing there, they differentiate and lose this ability to divide.
18
Q
What do keratinocytes synthesise?
A
Keratins
19
Q
What are keratins?
A
Large masses of fibrous proteins
20
Q
Where are keratins produced from?
A
Keratinocytes (found in the epidermis of the skin).
21
Q
Other than collagen, what contributes to the strength of the epidermis?
A
Keratins
22
Q
What is the function of keratins?
A
Contributes to the strength of the epidermis.
23
Q
What are keratins the main constituents of?
A
Hair and nails (and animal horns)
24
Q
What are your hair and nails predominantly made out of?
A
Keratin, they are just pure keratin really.
25
What is the normal transit time of a keratinocyte from basal layer to stratum corneum?
28-40 days (around 5 weeks)
| 21-28 days: 3-4 weeks NHS
26
The normal transit time of a keratinocyte is 28-40 days (around 5 weeks). What is this referring to?
Its differentiation from basal layer to stratum corneum.
27
Of which cell in the epidermis, is the normal transit time 28-40 days (around 5 weeks)?
Keratinocytes
28
What is psoriasis?
Psoriasis is a skin condition that causes red, flaky, crusty patches of skin covered with silvery scales.
29
What is the transit time of a keratinocyte in psoriasis?
5-6 days
| 3-7 days NHS
30
Explain what a normal transit time of a keratinocyte is and how associated problems with this can lead to disease.
The normal transit time of a keratinocyte is 28-40 days (~5 weeks). This describes how long it takes for the keratinocyte to differentiate in the basal layer of the epidermis, and move upwards to the outermost layer of skin (stratum corneum) where it drops off.
In some diseases, such as psoriasis, this transit time is greatly reduced (to about 3-7 days [about 5-6]), so that masses of stratum corneum is formed, which presents as silvery scales.
31
How does psoriasis present on the skin?
As silvery scales
32
What part of the skin produces the silvery scales seen on the skin in psoriasis?
Stratum corneum (build up of dead cells)
33
What is the pathophysiology of psoriasis?
The transit time is reduced, such that stratum corneum is produced in abundance as silvery scales.
34
How does psoriasis affect the patient?
It has huge psychosocial impact - masses of skin dropping off everywhere they go/every time they sit/stand etc. can be very distressing to the patient. Similarly, we have so much of our skin on show, so any 'deformities' have very obvious negative physical connotations socially, thus can impact heavily psychosocially.
NHS: The effect that psoriasis can have on physical appearance means low self-esteem and anxiety are common among people with the condition. This can lead to depression, especially if the psoriasis gets worse.
Your GP or dermatologist will understand the psychological and emotional impact of psoriasis, so talk to them about your concerns or anxieties.
35
Describe the psychosocial impact psoriasis has on a patient.
It has huge psychosocial impact - masses of skin dropping off everywhere they go/every time they sit/stand etc. can be very distressing to the patient due to the social impact. Similarly, we have so much of our skin on show, so any 'deformities' have very obvious negative physical connotations socially, thus can impact heavily psychosocially.
NHS: The effect that psoriasis can have on physical appearance means low self-esteem and anxiety are common among people with the condition. This can lead to depression, especially if the psoriasis gets worse.
Your GP or dermatologist will understand the psychological and emotional impact of psoriasis, so talk to them about your concerns or anxieties.
36
What can VERY rarely arise from skin due to keratin?
'Horns' of keratin (cutaneous horn)
37
How often can keratin horns arise from the skin?
Very rarely
38
What are 'horns' of keratin known as?
Cutaneous horns
39
What is a cutaneous horn?
A horn of keratin that has arisen.
40
How do you treat a keratin horn?
Surgical removal quite easily
41
Fig. 52 (left)
What are these images showing?
Keratin horns
42
Draw an image of a keratin horn (straight).
See Fig. 52 (left)
- they more often occur in older patients
- can have a risk of malignancy associated with it
- often occur on the head bc it's sun exposed
Other signs and symptoms, see below:
https://www.dermnetnz.org/topics/cutaneous-horn/
43
Draw an image of a keratin horn from the side.
See Fig. 52 (top right)
- they more often occur in older patients
- can have a risk of malignancy associated with it
- often occur on the head bc it's sun exposed
Other signs and symptoms, see below:
https://www.dermnetnz.org/topics/cutaneous-horn/
44
Draw an image of a keratin horn (spiral).
See Fig. 52 (bottom right)
- they more often occur in older patients
- can have a risk of malignancy associated with it
- often occur on the head bc it's sun exposed
Other signs and symptoms, see below:
https://www.dermnetnz.org/topics/cutaneous-horn/
45
As well as keratinocytes, what other cell types are found in the epidermis?
- Langerhans cells
| - Melanocytes
46
Where, specifically, are Langerhans cells found?
In all cell layers of the epidermis, but predominantly, the prickle cell layer (stratum spinosum) - roundabout in the middle.
47
What are Langerhans cells?
Dendritic cells (antigen-presenting immune cells) which have a huge immunological function.
48
What are the dendritic cells found in the epidermis called?
Langerhans cells.
49
Which layer of the epidermis are melanocytes found?
In the basal layer
50
What do melanocytes produce?
Melanin
51
What does melanin do to our skin?
Gives our skin its colour, especially, and more so if we're exposed to sunlight.
52
Fig. 53
Caption the image
High power photomicrograph of human epidermis, with S100 monoclonal antibody staining to demonstrate Langerhans cells and melanocytes (by coincidence these two unrelated cell types stain with the same reagent)
53
Fig. 53
Label the image
- Langerhans cells (prickle cell layer)
- Melanocytes (basal cell layer)
(Stratum corneum visible at the top
Granular layer underneath
Dermis visible with interdigitation of epidermis/dermis boundary clearly demarcated)
54
Draw a photomicrograph of a human epidermis,
See Fig. 53
- Langerhans cells (prickle cell layer)
- Melanocytes (basal cell layer)
(can be same colour as they react to the same reagent in dye - but must be in different layers)
(Stratum corneum visible at the top
Granular layer underneath
Dermis visible with interdigitation of epidermis/dermis boundary clearly demarcated)
55
Name 4 facts about melanocytes (other cells of the epidermis).
* occur at intervals(1:8 of basal layer of epidermis)
* difficult to see histologically without special stains
* produce melanin, the main pigment that gives the skin its colour
* produce more melanin but are not increased in number in black or tanned skin
56
Name 4 facts about Langerhans cells (other cells of the epidermis).
* difficult to see histologically without special stains
* highly specialised capacity to present antigens to T lymphocytes
* mediate immune reactions e.g. allergic contact dermatitis
57
How prominent are melanocytes in our skin?
They occur at intervals, they’re about 1 in 8 of all the basal cells of the epidermis, the rest are keratinocytes,
58
What is the ratio of melanocytes to the rest of the basal cells?
1:8 (in all ethnic origins)
59
Melanocytes appear at an interval of 1:8 in the basal layer. What are the other cells?
Keratinocytes
60
What cells of the skin are difficult to see histologically without special stains?
- Melanocytes
| - Langerhans cells
61
What cells makes up the basal layer of the skin?
Melanocytes and keratinocytes in a 1:8 ratio
62
How do we get our skin colour?
Melanocytes in the basal layer produce melanin, the main pigment that gives the skin its colour
63
What makes black/tanned skin people darker than white?
Although the melanocyte numnber is the same (1:8 ratio in basal layer; same ratio of melanocytes as we have to normal keratinocytes), it’s just that if we have more colour, we produce more melanin and also breaks down more slowly
64
What is the ratio of melanocytes to keratinocytes in people with tanned/dark skin?
It is the same (more melanin is produced/slower breakdown to give the darker colour)
65
What happens to the melanin produced by melanocytes in people with darker/tanned skin?
A More is produced and there is less breakdown
B. The melanin is conjugated with an enzyme and used for other purposes
C. The amount produced by the melanocyte is the same, but there are more melanocytes
D. More is produced but breakdown is the same
E. The same amount is produced but the breakdown is less.
A. More is produced and there is less breakdown
The amount of melanocytes stay the same, no matter what colour skin, but the amount of melanin produced differs with race.
66
What are melanosomes?
Organelles produced by melanocytes for synthesising, storing and transporting melanin.
67
# Define these terms:
Melanin
Melanosome
Melanocyte
Melanocyte: cell found in the basal layer of the epidermis (at a 1:8 ratio, regardless of race) which produces melanin
Melanosome: organelle found in the melanocyte which synthesises, stores and transports melanin
Melanin: pigment produced by melanocytes in the melanosome, which gives skin its colour
68
How do melanosomes differ for different races?
In a lighter person, the body tends to break down the melanosomes quite quickly, whereas in people of colour, it would do so much more slowly and would have a limit
69
What is the function of Langerhans cells?
They have a highly specialised capacity to present antigens to T lymphocytes
70
How do Langerhans cells act to help immunologically?
- highly specialised cells
- can present T cells to an antigen
- found in our outermost layer of our epidermis
- look for anything foreign, if they find it, they
- engulf it
- break it down
- puts on MHC Class II molecules
- travels through lymphatic system
- shows to T lymphocytes
- tells them to clone and expand
- T lymphocytes migrate back preferentially to the skin and they react
71
How do Langerhans cells recruit T lymphocytes?
Once a foreign antigen has been located, they engulf it and break it down, putting it onto an MHC Class II molecule. This is then able to travel through the lymphatic system which can be recognised by T lymphocytes, which, in turn, clone and expand, before they migrate back (preferentially to the skin) where they react.
72
What do Langerhans cells particularly have a role in?
They particularly mediate immune reactions.
73
What disease can Langerhans cells be involved in?
Allergic contact dermatitis.
74
What do melanocytes look like?
They sit in the basal layer with their long processes.
75
What is the function of the long processes of the melanocytes?
They wriggle around amongst the keratinocytes
76
How do keratinocytes and melanocytes interact?
It’s thought that the keratinocytes actually phagocytose off bits of these long processes [from the melanocytes] together with the little melanosomes inside them, and they come to line therefore, the melanosome come to line the keratinocytes, giving the skin its colour.
77
What is the mechanism which gives skin it's colour?
It’s thought that the keratinocytes actually phagocytose off bits of these long processes [from the melanocytes] together with the little melanosomes inside them, and they come to line therefore, the melanosome come to line the keratinocytes, giving the skin its colour.
78
Where in the basal layer do the melanocytes lie, specifically?
It's thought that they come to lie on the 'sunny side' as it were, the outer surface of the nuclei bc they’re main job is to protect the DNA from UV radiation so we don’t develop cancers
79
Why is it thought that melanocytes lie on the outer surface of the nuclei?
Bc they’re main job is to protect the DNA from UV radiation so we don’t develop cancers
80
How do melanocytes transfer our colour to the skin (keratinocytes)?
Mature melanosomes, containing melanin, are transferred to neighbouring keratinocytes by pigment donation, involving phagocytosis of the tips of the dendritic processes.
81
What process does the keratinocyte perform when it interacts with the melanocyte?
Phagocytosis
82
Fig. 55
Caption and label this image.
EPIDERMIS
- Langerhans' cell
- keratinocyte
- melanocyte
83
Draw an artists' depiction of a cross-section of the skin section, depicting the different cells found in the epidermis.
See Fig. 55
EPIDERMIS
- Langerhans' cell (dendritic cell found in middle layer - prickle cell layer)
- keratinocyte (main cells making up the epidermis)
- melanocyte (found in the basal layer, has long processes that interact/line the keratinocytes).
84
How do melanosomes sit in our skin?
In reality, we believe that melanosomes sit on the 'sunny side' of our nuclei in our epidermis, like little caps, protecting them from DNA damage by UV radiation.
85
What's the advantage of having darker skin?
The DNA in your keratinocytes is far better protected from UV light
86
Why does having paler skin give you a predisposition for developing malignant melanoma (compared to darker skin)?
The DNA in your keratinocytes is far better protected from UV light in people with darker skin, due to the increased production of melanin.
87
A 50 year old male presents at the skin clinic. What is the likelihood of him having malignant melanoma?
Black person: probably no malignancy; no odd moles or anything
White person: more at risk of having malignant melanoma, particularly if they have had prolonged exposure to the sun
88
A 50 year old Caucasian male presents to his GP with 3 moles. He has a history of 6.5 years of life in tropical sun with no sunscreen.
a) What are your current differential diagnoses?
- Malignant melanoma
| - Other skin cancers (benign or malignant)
89
A 50 year old Caucasian male presents to his GP with 3 moles. He has a history of 6.5 years of life in tropical sun with no sunscreen.
b) What further questions do you need to ask him before you make your diagnosis?
- How long have you had them?
- Have you noticed any changes in shape/size?
- Have you got any family history of anything like this?
- Do you have any other medical conditions (in particular skin conditions)?
- Do you have any allergies?
- Are you on any medications?
90
A 50 year old Caucasian male presents to his GP with 3 moles. He has a history of 6.5 years of life in tropical sun with no sunscreen.
c) After questioning, you are worried it could be malignant melanoma. What is your action towards these moles?
- Can watch them and see if they change if benign
- Have them frozen off.
- Surgery if progresses to malignant
91
A 50 year old Caucasian male presents to his GP with 3 moles. He has a history of 6.5 years of life in tropical sun with no sunscreen.
d) Thankfully, it transpires the moles were not malignant melanoma. What do you now tell the patient?
Bc he has spent a considerable amount of time in the sun, he needs to be careful and keep an eye on his skin - come back to the doctor if he notices any other changes/skin moles. Whilst out in the sun, make sure he uses sunscreen SPF Factor 50, and wear a t-shirt and hat outdoors at the brightest times (10AM - 3PM).
92
A 50 year old Caucasian male presents to his GP with 3 moles. He has a history of 6.5 years of life in tropical sun with no sunscreen.
e) If the patient did have malignant melanoma, how would you explain what this is to a patient?
Malignant melanoma is a type of skin cancer. The most appropriate treatment is surgery, and the best option is to catch it quick before it can spread to other places.
93
White skin is more prone to UV damage than darker skin. Why, then, do we have this rather useless mutation if you are much more likely to get malignant melanoma from whiter skin?
In less tropical climates, such as the Northern hemisphere and various Southern climates (further from the equator), less UV light penetrates the ozone. This means less UV light will penetrate the skin, so having a lighter mutation allowed for more UV light to penetrate through the skin, thus facilitating vitamin D3 production - the lighter skin was an advantageous mutation to allow humans to produce more vitamin D in less UV light (bc UV light is essential for making vitamin D).
94
What are the advantages and disadvantages to mutations in having lighter or darker skin?
Lighter skin:
Advantage: faciliates more vitamin D production in climates that receive less UV light
Disadvantage: less protection from UV damage
Darker skin
Advantage: much more protection to sunlight
Disadvantage: if in climate where there is less UV light, at risk of vitamin D deficiency
Thus, the benefits also depend on the climate - in tropical climates darker skin is at its peak because you get UV light protection and sufficient vitamin D production, but in colder climates you run the risk of vitamin D deficiency. Conversely, in cooler climates lighter skin can prevail bc they are able to make more vitamin D, but they are less protected on hot, sunny days.
95
What can vitamin D deficiency lead to?
Rickets (children) or osteomalacia (adults)
96
What is rickets?
Rickets is a skeletal disorder that affects bone development in children, due to a lack of vitamin D, calcium and phosphate. It causes bone pain, poor growth and soft, weak bones that can lead to bone deformities.
Adults can experience a similar condition, which is known as osteomalacia or soft bones.
97
What is osteomalacia?
Similar to rickets, but occurs in adults.
98
What is UV light essential for?
Vitamin D production in skin
99
What do we need for vitamin D production?
UV light
100
Fig. 56
Explain why the Caucasian child is more likely to develop malignant melanoma than the other children.
Darker skin is protected from UV radiation due to the increased production of melanin. As the child is growing up in the same tropical environment, his skin does not confer the same protection as whiter skin does not produce the same amount of melanin, thus, he is more susceptible to risk of UV damage.
101
Draw an image depicting which groups are at risk of UV damage and explain why.
See Fig. 56
Darker skin is protected from UV radiation due to the increased production of melanin. As the child is growing up in the same tropical environment, his skin does not confer the same protection as whiter skin does not produce the same amount of melanin, thus, he is more susceptible to risk of UV damage.
102
Where is stratified squamous keratinised epithelia found?
- Surface of skin
| - Limited distribution in oral cavity
103
What is the significance of knowing there is stratified squamous keratinised epithelia in your oral cavity (limited distribution)?
If you mouth breathe a lot you can get some keratin forming on your gums and tongue.
104
How can you get keratin forming on your gums and tongue?
If you mouth breathe - due to the (limited distribution of) stratified squamous keratinised epithelia in your oral cavity.
105
What epithelia is found on the surface of your skin?
Stratified squamous keratinised epithelia
106
What epithelia is found in a limited distribution in the oral cavity?
Stratified squamous keratinised epithelia
107
Name 4 functions of stratified squamous keratinised epithelia.
- Protection against abrasion and physical trauma
- Prevention of water loss
- Prevention of microbial ingress
- Shielding against UV light damage
108
Explain how stratified squamous keratinised epithelia has a role in protection against abrasion and physical trauma,
The stratified dead cells at the top are continuously falling off, so any abrasions cut this layer, and does not lead to bleeding from layers below (epithelia is avascular).
109
Explain how stratified squamous keratinised epithelia has a role in prevention of water loss.
Vasoconstriction helps prevent water loss by not allowing the sweat to evaporate from the excess heat carried by the blood.
110
Explain how stratified squamous keratinised epithelia has a role in prevention of microbial ingress.
Creates a thick barrier for microbes not to pass through. Also, the presence of Langerhans cells means foreign bodies can be fought.
111
Explain how stratified squamous keratinised epithelia has a role in shielding against UV light damage.
Melanocytes produce melanin which protect from UV light damage.
112
Why is transitional epithelium so-named?
These cells are called transitional bc they vary in shapes
113
How can transitional epithelium appear?
Sometimes they look quite columnar, other times they look really flattened
114
What dictates the shape of transitional epithelium?
It depends whether the epithelium is stretched or relaxed
115
What is the shape of transitional epithelium when relaxed?
Columnar/cuboidal
116
What is the shape of transitional epithelium when stretched?
Flattened (squamous)
117
When does transitional epithelium appear almost columnar?
When relaxed
118
When does transitional epithelium appear squamous?
Squamous = flattened, so when stretched
119
Define transitional epithelium.
Surface cells vary in shape from columnar/cuboidal to flattened
120
Fig. 58
Label and caption the image.
Transitional relaxed (left)
Transitional stretched (right)
```
Transitional epithelium
(surface cells vary in shape from columnar/cuboidal to flattened)
```
121
Draw an image depicting transitional epithelia.
See Fig. 58
Transitional relaxed (left)
Transitional stretched (right)
```
Transitional epithelium
(surface cells vary in shape from columnar/cuboidal [relaxed] to flattened [stretched])
```
122
Where is transitional epithelium often found?
Lining the whole urinary tract, all the way from the calyces of the kidney to the urethra.
123
What is transitional epithelium sometimes known as?
Urothelium
124
What is urothelium?
The transitional epithelium of the urinary tract.
125
Where is transitional epithelium in the kidney found?
In the calyces
126
What epithelia is found in the calyces of the kidney?
Transitional epithelia
127
What does transitional epithelium sit on?
A basement membrane
128
How do the cells of the in the relaxed urothelium appear?
Rather columnar
129
Fig. 59
Label this image.
Ep - Transitional epithelium (Ep) or 'urothelium' of the relaxed ureter
BV - Connective tissue containing Blood vessels (BV).
130
Draw an image of relaxed transitional epithelium of the ureter as it would appear on a histology slide.
See Fig. 59
Ep - Transitional epithelium (Ep) or 'urothelium' of the relaxed ureter (MUST be columnar/cuboidal, but NOT flattened)
BV - Connective tissue containing Blood vessels (BV).
(Basement membrane lies in between)
131
What does the connective tissue below the urothelium contain?
Blood vessels
132
What contains the blood vessels in transitional epithelium?
The connective tissue below it
133
Fig. 60
Caption and label this image.
Transitional epithelium (Ep) of the relaxed bladder (with a different stain).
- Ep
134
Fig. 60
How can you recognise this as relaxed epithelium of the bladder?
- Due to its distinctive lobulated appearance of the relaxed bladder wall
135
How does the relaxed bladder wall appear under a microscope?
Has a lobulated appearance
136
Draw the transitional epithelium of the relaxed bladder.
See Fig. 60
Transitional epithelium (Ep) of the relaxed bladder (with a different stain) - has a lobulated appearance
- Ep
137
How do transitional cells of the bladder appear when stretched?
The cells are columnar but lying the other way if you like, they’re approaching being squamous cells,
138
When does transitional epithelium appear squamous?
When the tissue is stretched (e.g. in bladder distension).
139
Why are transitional epithelium able to change shape?
This gives them an enormous ability to stretch without breaking, but also, a good ability to avoid the ingress of toxins from the urine into the subtending connective tissue.
140
How does the bladder stretch without breaking?
It is lined by transitional epithelium, which changes shape when relaxed and stretched.
141
How does the bladder prevent ingress of toxins from the urine into its subtending connective tissue?
It is lined by transitional epithelium, which changes shape when relaxed and stretched.
142
Fig. 61
How did they take this image?
- Distended the bladder
- Fixed it
- Stained it
143
Fig. 61
Caption and label the image.
Transitional epithelium (Ep) of the distended bladder.
- Ep
144
Draw an image of how the distended bladder would look on a histology slide
See Fig. 61
Transitional epithelium (1) (Ep) of the distended bladder. Epithelium appears squamous (1)
- Ep
145
Where is transitional epithelium found?
Transitional epithelium = urinary epithelium (urothelium)
So the urinary tract:
from renal calyces --> ureters --> bladder --> urethra
146
What type of epithelium is urinary epithelium (urothelium)?
Transitional epithelium
147
What epithelium lines the urinary tract?
Transitional epithelium
148
What does the urinary tract include?
Renal calyces --> ureters --> bladder --> urethra
149
What is the urinary system, from renal calyces to urethra?
Renal calyces --> ureters --> bladder --> urethra
150
What epithelium lines the renal calyces?
Transitional epithelium
151
What epithelium lines the ureters?
Transitional epithelium
152
What epithelium lines the bladder?
Transitional epithelium
153
What epithelium lines the urethra?
Transitional epithelium
154
What are the functions of the transitional epithelium?
- Distensibility
| - Protection of underlying tissue from toxic chemicals
155
What epithelium is involved in distensibility?
Transitional epithelium
156
What epithelium is involved in protection of underlying tissue from toxic chemicals?
Transitional epithelium
157
What are glands (mainly) derived from?
Epithelia
158
Epithelia can go on to derive what structures specialised for secretion?
Glands
159
What is a gland?
A GLAND is an epithelial cell or collection of cells specialised for secretion.
160
How many cells is a gland?
Can be one cell or a collection of cells.
161
Where do glands secrete their substances?
The secretion can be into the bloodstream or onto an epithelial surface
162
Give 3 examples of epithelial surfaces glands can secrete their substances to?
i.e. the gut, respiratory or reproductive tracts
163
Glands can secrete onto the gut, respiratory or reproductive tracts. What are these examples of?
Epithelial surfaces
164
Define the term adenocarcinoma.
The term, ADENOCARCINOMA, means a malignant growth (1) derived from glandular cells (1) of epithelial origin (1).
*learn*
165
A malignant growth derived from glandular cells of epithelial origin is known as what?
ADENOCARCINOMA
166
Epithelial cell(s) specialised for secretion are known as what?
A gland (can be one cell or a collection)
167
Is an adenocarcinoma malignant or benign?
Malignant
168
Where are adenocarcinomas derived from?
Glandular cells (of epithelial origin)
169
Where do the cells that make up an adenocarcinoma originate from?
(Glandular cells of) epithelial origin
170
How are glands classified?
There are many ways, but the most important classification is by its secretion.
171
What are the two terms used to classify glands by secretion?
Exocrine
| Endocrine
172
Define exocrine.
Glands with ducts, which secrete onto an epithelial surface
*learn*
173
What type of gland are glands with ducts, which secrete onto an epithelial surface?
Exocrine
174
Where do glands with ducts secrete onto?
An epithelial surface
175
Glands that secrete onto an epithelial surface have ducts. True or false?
True (exocrine gland)
176
Give 2 examples of exocrine glands.
Salivary gland
| Breast
177
The salivary gland is a type of _______ gland.
Exocrine
178
The breast has _____ glands.
Exocrine
179
What does it mean for a gland to have a duct?
The secretory cells themselves have a duct, or they combine to form a duct, and secrete onto an epithelial surface
180
Where do the ducts arise from in exocrine glands?
The secretory cells themselves have a duct, or they combine to form a duct
181
Define endocrine.
‘ductless glands’, which secrete into the bloodstream
*learn*
182
‘Ductless glands’, which secrete into the bloodstream are known as what?
Endocrine
183
What type of gland is ductless?
Endocrine
184
Where do endocrine glands secrete into?
The bloodstream
185
Compare and contrast two types of glands classified by their secretion. Give their name, structure and secretory surface.
Exocrine
- glands with ducts
- secretes onto an epithelial surface
Endocrine
- ductless glands
- secretes into the bloodstream
186
Give 2 examples of endocrine glands
- thyroid gland
| - adrenal gland
187
The thyroid gland is what type of gland?
Endocrine
188
The adrenal gland is what type of gland?
Endocrine
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What does the thyroid gland produce?
Thyroxine, straight into the bloodstream
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Where is thyroxine produced?
In the thyroid gland
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What is thyroxine?
A hormone produced by the thyroid gland that travels in the bloodstream
192
What do the adrenal glands produce?
All sorts of hormones, including adrenaline
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Where is adrenaline produced?
In the adrenal glands (and some other places)
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What is a adrenaline?
A hormone produced by the adrenal glands that travels in the bloodstream
195
It can be said that endocrine glands technically secrete onto an epithelial surface. How is that true?
They secrete onto the endothelium, but it's carried away by the blood straight away.
196
What are mixed glands?
Glands that have both exocrine and endocrine cell types/secretion within them
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Give an example of a mixed gland.
Pancreas
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What type of gland is the pancreas?
A mixed gland - contains both exocrine and endocrine secretory elements.
