Glandular Tissues and Cell Secretion Flashcards
1
Q
What is a gland?
A
An epithelial cell or collection of cell specialised for secretion
2
Q
How can glands be classified?
A
- Destination
- Structure
- Nature
- Method
3
Q
What can glands be classified into based on destination?
A
NAME?
4
Q
What do exocrine glands have?
A
Ducts
5
Q
Where do exocrine glands secrete?
A
Onto epithelial surfaces
6
Q
What do endocrine glands produce?
A
Hormones
7
Q
Where do endocrine glands secrete?
A
Into the bloodstream
8
Q
What can glands be classified into base on structure?
A
NAME?
9
Q
What are the possible differences between the secretory part of a gland?
A
- Is it unicellular or multicellular?
- It it acinar (alveolar) or tubular?
- Is it coiled or branched?
10
Q
What are the different types of duct systems?
A
- Simple gland
- Compound gland
11
Q
What is meant by a simple gland?
A
Single duct
12
Q
What is meant by a compound gland?
A
Branched ducts
13
Q
How to ducts branch?
A
From main duct → interlobular → intralobular → intercalated
14
Q
What do ducts define?
A
The structure of complex glands
15
Q
What kind of gland is a goblet cell?
A
Unicellular exocrine
16
Q
Where are goblet cells found?
A
In pseudostratified epithelium of respiratory system
17
Q
Where is the ion channel molecule CFTR normally found?
A
The apical membrane
18
Q
In what condition is the CFTR protein not present?
A
Cystic Fibrosis
19
Q
Why is the CFTR protein not present in CF?
A
The mutant protein is normally destroyed before it reaches the apical membrane
20
Q
What is the result of the absent CFTR gene?
A
Cl - transport across membrane seriously compromised
21
Q
What is the result to mucous of the compromisation of Cl - transport across the membrane?
A
It becomes viscous
22
Q
Why does faulty Cl - transport lead to viscous mucous?
A
The lack of Cl - , and therefore Na + (as sodium usually follows Cl - ), changes the osmotic potential, which means that water doesn’t leave the epithelium in sufficient quantities, so the mucus is not adequately hydrated, thus becoming viscous
23
Q
What problems does viscous mucus cause?
A
- Serious pulmonary infection
- Meconium ileus
- Constipation
- Invagination of parts of GI tract
24
Q
How does viscous mucus result in serious pulmonary infection?
A
Because the mucus can’t be as readily moved to oropharynx for swallowing
25
What is meconium ileus?
Inability to pass first faeces
26
What causes the GI symptoms of CF?
Viscous mucus of the GI tract
27
What happens to pancreatic ducts as they merge towards epithelium?
They become bigger
28
When are multicellular glands considered simple?
If the ducts do not branch
29
Give the 4 types of simple glands
- Simple tubular
- Simple coiled tubular
- Simple branched tubular
- Simple acinar
30
When are multicellular glands compound?
If the ducts branch
31
Give the 3 types of compound glands
#NAME?
32
What is a compound tubuloalveolar gland?
A mixture of tubular and alveolar
33
What can glands be classified into by nature of secretion?
- Mucous
| - Serous
34
What do mucous glands produce?
Secretions that contain mucins
35
What are mucins?
Highly glycosylated polypeptides
36
What happens to mucins with later?
They swell a lot
37
How do mucous cells stain with H&E sections?
Poorly
38
What do serous membranes secrete?
#NAME?
39
How do serous cells stain in H&E sections?
Pink, as they are eosinophilic
40
What can glands by classified into based on method of secretion?
#NAME?
41
What kind of secretion do the vast majority glands use?
Merocrine
42
What is merocine secretion also known as?
Exocytosis
43
Describe the process of merocrine secretion
- Membrane bound component approaches cell surface
- Bounded membrane fuses with plasma membrane
- Contents in continuity with extracellular space
44
What has happened to the plasma membrane following merocrine secretion?
It is transient larger
45
What must happen to the plasma membrane following merocrine secretion?
It must be retrived
46
Why must the plasma membrane be retrieved following merocrine secretion?
It stabilised the cell SA, otherwise the membrane would get very big
47
Describe the process of apocrine secretion
- Non-membrane bound structure approaches the cell surface membrane
- Makes contact and pushes up apical membrane, so a thin layer of cytoplasm drapes around the droplet
- Membrane surrounding droplet pinches off from the cell
48
Give an example of a type of molecule that may use apocrine secretion?
Lipid
49
What happens to the plasma membrane following apocrine secretion?
It is transiently smaller
50
What needs to be done following apocrine secretion?
Membrane needs to be added to regain the area
51
Give an example of where apocrine secretion occurs?
Mammary gland
52
What is secreted from the acini of the mammary gland?
Milk
53
What is needed to assist secretion in the mammary gland?
Myoepithelial cells
54
What kind of secretion to apocrine sweat glands use?
Merocrine
55
Why are apocrine sweat glands contradictorily named?
Because cytoplasmic blebbing not indicative of apocrine secretion
56
Where do apocrine sweat glands occur?
#NAME?
57
What kind of secretion do eccrine sweat glands use?
Merocrine
58
How do eccrine sweat glands work?
The myoepithelial cells contract, facilitating transport of luminal contents towards the duct
59
What can sweat testing for abnormally salty sweat confirm?
A CF diagnosis
60
Why do CF sufferers have abnormally salty sweat?
Because the absence of CFTR proteins in the apical membrane of epithelial cells lining the ducts of the sweat gland results in poor reabsorption of chloride ions, resulting in sweat rich in them
61
What kind of sweat does a heathy person secrete?
Hypotonic
62
Why do people normally secrete hypotonic sweat?
Don’t want to waste ions
63
Describe the process of holocrine secretion
#NAME?
64
Give an example of somewhere holocrine secretion occurs?
Sebacous gland
65
What does a sebaceous gland do?
Undergoes holocrine secretion to fill the hair follice with sebum
66
What is endocytosis?
Engulfing material initially outside the cell
67
Where are endo- and exocytosis coupled?
In trans-epithelial transport
68
Describe the process of trans-epithelial transport
#NAME?
69
What can happen to molecules too large to penetrate membranes?
They can be shunted from one component of the body to another by trans-epithelial transport
70
Do molecules in trans-epithelial transport cross membranes?
No
71
Describe the structure of the Golgi apparatus
- Stack of disk shaped cisternae
- One side flattened, other concave
- Disks have swellings at edges
72
In what direction to substances move through the Golgi?
From the flat to concave surface
73
What happens to the swellings at the edge of the Golgi cisternae?
Distal swellings pinch off as migratory Golgi vacuoles
74
What is glycosylation?
Adding sugar to proteins
75
Where does glycosylation occur?
In the cisternae of the Golgi
76
What is the function of the Golgi?
- Sorting into different compartments
- Packing through condensation of contents
- Glycosylation
- Transport of resultant vesicles
77
How does the Golgi sort into different components?
Puts them into different vacuoles
78
How do vesicles transport through the Golgi?
Move through the Golgi in 1 direction
79
Where are the products from the Golgi destined?
- Majority extruded in secretory vesicles
- Some retained for use in cells
- Some enters plasma membranes
80
What glands extrude products from the Golgi in secretory vesicles?
All those secreting substances like mucus onto epithelial surfaces
81
Give an example of where Golgi products are retained for use in cells?
Lysosomes
82
Give an example of where Golgi products enter the plasma membrane?
Glycocalyx
83
What is the advantage of glycosylation?
Branching sugars offer complex shapes, which allow for specific interactions in glycocalyx
84
How do glycosylated proteins interact with other proteins?
In a very specific way
85
Why does glycosylation have the potential for such specificity?
Because although there are only 6 to 8 sugar monomers, they can produce 1000’s of sugars if they’re put together in different combinations
86
What happens if the glycosylated layer is destroyed by enzymes?
It alters many specificity based properties of the cell
87
What properties of a cell might be altered by destruction of the glycosylated layer?
- Adhesion to substrates and neighbouring cells
- Mobility
- Communication with neighbouring cells
- Contact inhibition of movement and division
88
How can secretion be controlled?
- Nervous
- Endocrine
- Neuro-endocrine
- Negative feedback of chemical mechanism
89
Give an example of nervous control of secretion
Sympathetic stimulation of adrenal medullary to release adrenaline
90
Give an example on endocrine control of secretion
ACTH stimulates the adrenal cortex to secrete hormones such as cortisol
91
Give an example of neuro-endocrine control of secretion
Nervous cells of hypothalamus controls ACTH secretion
92
Give an example of negative feedback on a chemical mechanism controlling secretion
Inhibitory effect of high thyroxine (T3 and T4) on TSH synthesis
93
Give 3 examples of exocrine glands
- Unicellular glands (goblet cells)
- Parotoid glands
- Submandibular glands
94
Where are goblet cells found?
Jejenum and colon
95
Give 4 examples of endocrine glands
- Pancreas
- Thyroid gland
- Parathyroid glands
- Adrenal (superarenal) glands
96
What are the 3 main salivary glands?
- Parotid
- Submandibular
- Sublingual
97
Are salivary glands mucus or serous?
Mixed
98
What are serous demilumes?
An artifactual crescent moon of serous tissue
99
What causes serous demilumes?
With conventional fixation, mucous cells swell, releasing mucus, which squeezes serous cells out to the edge
100
Is the pancreas exocrine or endocrine?
Both
101
Where is the head of the pancreas?
In the curl of the duodenim
102
What does the pancreas do?
- Churns out alkaline bicarbonate ions
- Releases digestive enzymes
- Produce insulin and glucagon
103
Why does the pancreas churn out bicarbonate ions?
To neutralise the acid released by the stomach
104
Why does the acid released by the stomach need to be neutralised?
Because the small intestine is not adapted to highly acidic conditions
105
Give 4 digestive enzymes released by the pancreas
#NAME?
106
What happens to the insulin and glucagon produced by the pancreas?
It’s secreted into the bloodstream
107
What is wrong with the secretions of the pancreas in cystic fibrosis?
They contain too little water, and so become thickened
108
What is the result of the thickened secretions of the pancreas?
The ducts become blocked
109
What is the result of blocked pancreatic ducts?
- Painfully inflamed pancreas (pancreatitis)
- Pancreas becomes fibrotic
- Gut receives insufficient pancreatic digestive enzymes, which results in malabsorption
110
What does malabsorption lead to?
Secretion of fat in faeces and diarrhoea
111
How does the rate of deterioration of the endocrine pancreas differ from that of the exocrine?
It’s slower
112
Why is the rate of deterioration of the endocrine pancreas slower?
Because it has no exocrine ducts
113
What are 3 cell types of pancreatic islets of Langerhans?
- Alpha
- Beta
- Delta
114
What does each islet of Langerhan have?
An exocrine acinus
115
What does the thyroid gland consist of?
Simple cuboidal epithelium follices
116
Where is the thyroid gland found?
Wrapped around the trachea
117
What does each follicle have?
Homogenous colloid
118
What does the thyroid gland need to perform its function?
Good blood supply
119
Why does the thyroid gland need good blood supply?
Because it’s an exocrine gland, and so is secreting into the bloodstream
120
What happens to the lining cells of the thyroid gland when it’s active?
They become slightly columnar
121
What are the steps of thyroid hormone synthesis?
- Thyroglobulin is synthesised and secreted
- Uptake and concentration of iodine from blood
- Iodine is oxidised, and released into colloid
- Iodination of thyroglobulin in colloid
- Formation of T3 and T4 hormones by oxidative coupling reactions
- Resorption of colloid by receptor-mediated endocytosis
- Release of T3 and T4 from cell by exocytosis
122
What is the purpose of the thyroid gland?
It thyroxin in T3 and T4 states at correct level
123
What do parathyroid glands secrete?
Parathyroid hormone (PTH)
124
How many parathyroid glands are there?
Usually 2, sometimes 3, pairs
125
What does PTH control?
The level of calcium in the blood
126
What must be done in the case of a thyroidectomy?
The parathyroid glands must be left behind
127
Where are the adrenal glands found?
Sitting on top of each kidney
128
What does each adrenal gland consist of?
#NAME?
129
What does the adrenal medulla secrete?
Adrenaline and noradrenaline
130
What does the adrenal cortex produce?
Corticosteriod hormones
131
What does the adrenal cortex consist of?
3 layers, each producing different hormones
132
What are the 3 layers of the adrenal cortex?
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis
133
Which zone of the adrenal cortex is the closest to the artery?
Zona glomerulosa
134
What does the zona glomerulosa produce?
Aldosterone
135
What does the zona fasciculata produce?
Primarily, cortisol
136
What does the zona reticularis produce?
Primarily, weak male hormone
