ToB 3 Glandular tissues, and how cells secrete Flashcards

1
Q

Define gland:

A

An epithelial cell(s) specialised for secretion

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2
Q

What are the 4 properties of a gland, which allow classification?

A

1) Destination of secretion (or route it may take)
2) Structure of the gland
3) Nature of the secretion
4) Method of secretion

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3
Q

Define an exocrine gland:

A

A gland with duct(s), which secrete onto an epithelial surface.

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4
Q

Define an endocrine gland:

A

‘Ductless’ glands, which secrete into the bloodstream

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5
Q

What is secreted by an endocrine gland?

A

Hormones

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6
Q

What type of gland secretes hormones?

A

Endocrine glands

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7
Q

What is meant by a ‘simple gland’?

A

A gland which has a single duct, or ducts which do not branch

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8
Q

What is meant by a ‘compound gland’?

A

A gland which has branched ducts

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9
Q

How would you classify a gland with branched ducts?

A

Compound gland

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10
Q

Describe a goblet cell in glandular terms:

A

Unicellular exocrine gland which secretes mucous

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11
Q

Why is it important that mucous is rich in NaCl?

A

This allows the mucous to stay moist, as it creates a water potential gradient across the apical epithelial cell membrane, so water is likely to leave the cell (into the lumen).

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12
Q

Why do cystic fibrosis sufferers have viscous mucous?

A

They have a defective CFTR gene, resulting in a defective Cl- channel, so Cl- cannot leave the apical epithelial membrane, preventing the setup of a water potential gradient, so water doesn’t leave the cell (into the lumen).

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13
Q

What type of cell produces mucous?

A

Goblet cell

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14
Q

What does CFTR stand for?

A

cystic fibrosis transmembrane regulator

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15
Q

What is ‘meconium ileus’?

A

Bowel obstruction preventing infants passing their first faeces, due to viscous mucous.

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16
Q

What is the most common explanation for meconium ileus?

A

Cystic fibrosis (defective CFTR gene)

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17
Q

What does an acinus duct look like?

A

Grape on a stalk

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18
Q

What type of cells make up the acinus?

A

Acinar cells and ductule cells

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19
Q

Give an example of a simple tubular gland:

A

Intestinal glands

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20
Q

Give an example of a simple coiled tubular gland:

A

Merocrine sweat glands

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21
Q

What are the 3 methods of secretion from an exocrine gland?

A

1) Merocrine
2) Apocrine
3) Holocrine

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22
Q

What is meant by a ‘merocrine’ gland?

A

It is an exocrine gland, which secretes via exocytosis.

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23
Q

What is meant by an ‘apocrine’ gland?

A

A portion of the cell membrane buds off the apical side, containing the secretion.

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24
Q

What is meant by a ‘holocrine’ gland?

A

A glandular cell which disintegrates to release secretion

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25
Q

Give an example of a simple acinar gland:

A

These are not found in an adult, but are a development stage of simple branched acinar gland.

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26
Q

Give an example of a holocrine simple branched acinar gland:

A

Sebaceous gland of the skin/nose

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27
Q

How would you classify a gland in which the ducts are branched?

A

Compound exocrine gland

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28
Q

Give 3 examples of compound tubular glands:

A

1) Mucous glands in mouth
2) Bulbourethral glands
3) Testes

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29
Q

What do the bulbourethral glands secrete, and where?

A

A viscous, clear, salty liquid (pre-ejaculate), which neutralises residual acid in the urethra.

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30
Q

Give an example of a compound acinar gland:

A

Mammary glands

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31
Q

Give 3 examples of compound tubuloacinar glands:

A

1) Salivary glands
2) Glands of respiratory passages
3) Pancreas

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32
Q

What are the 2 types of secretion ‘nature’, used for classification?

A

1) Mucous glands

2) Serous glands

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33
Q

Describe ‘mucins’:

A

Highly glycosylated polypeptides, present in mucous. They swell in the presence of water.

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34
Q

How do mucous glands appear when stained with H&E?

A

Mucous glands stain poorly in H&E stain, so appear pale

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35
Q

Describe serous gland secretion:

A

Watery and free of mucous, often containing enzymes.

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36
Q

How do serous glands appear when stained with H&E?

A

They are eosinophilic, so appear pink.

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37
Q

If a cell is secreting via merocrine secretion, what must the cell do to retain its original surface area?

A

Because merocrine secretion is exocytosis, in which the secretion is encased in membrane which fuses with the cell membrane. This must be retrieved, to stabilise the cell surface area.

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38
Q

If a cell is secreting via apocrine secretion, what must the cell do to retain its original surface area?

A

Apocrine secretion is endocytosis, so membrane must be constantly added to the cell membrane to retain original surface area.

39
Q

A lactating mammary gland secretes via what method?

A

Apocrine secretion of fat droplets,

Merocrine secretion of protein

40
Q

What type of gland is a mammary gland?

A

Compound acinar exocrine gland

41
Q

What is present around a mammary gland to assist secretion?

A

Myoepithelial cells contract (‘let down’)

42
Q

Why is ‘sweat-testing’ often used to confirm a diagnosis of cystic fibrosis?

A

Due to a defective Cl- channel in the apical membrane of the epithelial cells lining sweat gland ducts, there is poor reabsorption of Cl-, leading to abnormally salty sweat.

43
Q

Is sweat usually hypertonic, isotonic, or hypotonic?

A

Hypotonic (contains less salt than normal body cells)

44
Q

Give an example of a holocrine gland:

A

Sebaceous gland cells (on skin)

45
Q

What is the function of a sebaceous gland cell?

A

Via holocrine secretion they fill the hair follicle on skin with sebum.

46
Q

Describe endocytosis:

A

When the cell ‘engulfs’ outside molecules into the cell, enveloped in part of the cell membrane.

47
Q

Describe exocytosis:

A

When vesicles inside the cell fuse with the cell membrane, releasing the contained molecules outside the cell.

48
Q

Describe the appearance of the Golgi Apparatus:

A

Stack of flattened sacs called cisternae

49
Q

Where does the glycosylation of newly synthesised proteins and lipids occur?

A

In the Golgi Apparatus

50
Q

What are the 2 methods of exocytosis of proteins from the Golgi Apparatus?

A

1) Constitutive secretion (continuous)

2) Regulated secretion (requires signal)

51
Q

What are the 3 possible destinations for the glycosylated products from the Golgi apparatus?

A

1) Extruded via secretory vesicles
2) Retained in cell
3) Enters plasma membrane

52
Q

Define glycocalyx:

A

A glycoprotein-polysaccharide covering which surrounds most animal epithelial cells, and some bacteria.

53
Q

What are the main 4 possible functions of the glycocalyx:

A

1) Adhesion - to neighbouring cells and substrates
2) Mobility of cells
3) Communication with neighbouring cells
4) Contact inhibition - of division and movement (of neighbouring cells)

54
Q

What is a key component of the glycocalyx for its specific interactions?

A

Branched sugar chains

55
Q

What are the 4 basic control mechanisms of secretion?

A

1) Nervous stimulation/inhibition
2) Endocrine
3) Neuro-endocrine
4) Negative feedback chemicals

56
Q

What control mechanism leads to the release of adrenaline in the body?

A

Sympathetic nervous stimulation of the adrenal medullary cells

57
Q

What control mechanism leads to the secretion of cortisol?

A

Endocrine stimulation: ACTH release stimulates adrenal cortex to release cortisol

58
Q

What does ACTH stand for?

A

Adrenocorticotrophic hormone

59
Q

Define ‘neuroendocrine’ cell:

A

A cell which receives neuronal stimulation, and consequently releases hormones

60
Q

How do thyroid hormones use negative feedback control?

A

High levels of T3/T4 inhibit further release of TSH (thyroid stimulating hormone)

61
Q

Name the 3 major salivary glands:

A

1) Parotid
2) Submandibular
3) Sublingual

62
Q

Does the submandibular salivary gland contain mucous or serous cells?

A

The submandibular gland secretes both mucous and serum (so both)

63
Q

Where are the submandibular glands, and where does their duct open?

A

Under the jawbone, with the duct opening at the front of the mouth under the tongue

64
Q

Where are the sublingual glands?

A

Under the tongue

65
Q

Where are the parotid glands?

A

Inside the cheek, just in front of the ears

66
Q

Does the parotid salivary gland contain mucous or serous cells?

A

Serous cells, it doesn’t secrete mucous

67
Q

Why are the serous cells sometimes referred to as ‘serous demilunes’?

A

After fixation serous cells which are in between mucous cells become distorted and form a demilune cap over the mucous cells. This is ARTEFACTUAL.

68
Q

Does the sublingual cells contain mucous or serous cells?

A

Both, but predominantly mucous cells.

69
Q

What type of a gland is the pancreas?

A

The pancreas is both exocrine and endocrine: compound acinus exocrine cells, but also endocrine cells in pancreatic islets.

70
Q

What type of secretory cells are present in the pancreatic duct?

A

Endocrine cells

71
Q

Why does cystic fibrosis usually cause pancreatitis?

A

The secretions of the exocrine pancreas contain too little water, which blocks the ducts, causing inflammation.

72
Q

Why is fat often present in the faeces of cystic fibrosis sufferers?

A

Cystic fibrosis causes the blockage of pancreatic ducts (due to thick secretions), which results in insufficient lipase secretion, causing malabsorption of fat.

73
Q

What is stored in the colloid of a thyroid follicle?

A

Thyroglobulin

74
Q

Where is thyroglobulin synthesised?

A

In the simple cuboidal epithelial cells in the thyroid gland

75
Q

What must the epithelial cells in the thyroid gland take up from the capillary in order to synthesise thyroid hormones?

A

Amino acids

Iodide

76
Q

Where does iodination of thyroglobulin (to synthesise T3/T4) occur?

A

In the colloid of thyroid follicles

77
Q

Are T3 and T4 hormones synthesised via oxidative or reductive coupling reactions?

A

Oxidative coupling reactions

78
Q

By what method of secretion do T3 and T4 leave the epithelial cells of the thyroid gland?

A

Exocytosis

79
Q

What shape is the thyroid gland?

A

Bow-tie shape (and position)

80
Q

How many parathyroid glands are there in the body, and where are they situated?

A

4, 2 in each lobe of the thyroid gland

81
Q

What are the 2 main types of cells in a parathyroid gland?

A

1) Principal (chief) cells
2) Oxyphil cells
3) Adipose cells

82
Q

Which cells in the parathyroid gland secrete PTH?

A

Principal (chief) cells

83
Q

How many adrenal glands are there in a body, and where are they situated?

A

2, one above each kidney

84
Q

What are the 3 zones within the adrenal cortex?

A

1) Zona reticularis
2) Zona fasciculata
3) Zona glomerulosa

85
Q

What way does blood flow through an adrenal gland?

A

From the cortex towards the medulla

86
Q

What type of hormones are secreted by the adrenal cortex cells?

A

Corticosteroid hormones

87
Q

Which hormones are secreted by the adrenal medullary cells?

A

Adrenaline

Noradrenaline

88
Q

What name is given to the layer surrounding the adrenal cortex?

A

Capsule

89
Q

What type of hormones are secreted by the zona glomerulosa in the adrenal cortex?

A

Mineralocorticoids

90
Q

Give an example of a mineralocorticoid:

A

Aldosterone

91
Q

What type of hormone is secreted by the zona fasciculata in the adrenal cortex?

A

Glucocorticoids

92
Q

What is the most abundant glucocorticoid hormone?

A

Cortisol

93
Q

What type of hormone is secreted by the zona reticularis?

A

Gonadocorticoids