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Define gland

- An epithelial cell or collection of cells specialised for secretion

1

What is an exocrine gland?

- Ducts with glands

2

What is an endocrine gland?

- A ductless gland that secretes directly into the bloodstream

3

How can glands be classified?

- Destination of secretion
- Structure
- Nature of secretion
- Method of secretion

4

How are glands classified by structure?

- Unicellular or multicellular
- Acinar (alveolar) or tubular
- Coiled or branched
- Simple or compound

5

Give an example of a unicellular gland

- Goblet cell in the upper respiratory tract and in the intestines

6

What happens to the gland in cystic fibrosis?

- Cystic Fibrosis Transmembrane Regulator ion channel molecule is not present in epithelial cells
- Chloride ions are not transported across the membrane out of the cell
- Water stays in the epithelium and does not diffuse into the respiratory tract lumen, causing the mucus to become viscous and dehydrated
- The mucus can no longer be moved easily and pulmonary infections can then occur

7

Give an example of an Acinar/alveolar gland

- Pancreatic exocrine acinar cells

8

What is the difference between simple and compound glands?

- Simple glands: have non-branching ducts
- Compound glands: branching ducts

9

How are glands classified by nature of secretion?

- Mucous or serous glands

10

What is a mucus gland?

- Secretions contain mucus, which is rich in mucins (highly glycosylated polypeptides)
- Cells stain poorly in H&E sections

11

What is a serous gland?

- secretions are often of enzymes, are watery and free of mucus
- stain pink (eosinophilic) in H&E sections

12

What are the major salivary gland?

- Parotid
- Submandibular
- Sublingual

13

How are glands classified by method of secretion?

- Merocrine
- Apocrine
- Holocrine

14

What is Merocrine secretion?

- Exocytosis
- Membrane bound vesicle approaches cell surface
- The vesicle membrane fuses with the plasma membrane
- Contents are in continuity with the extracellular space
- Plasma membrane is now larger
- Membrane is retrieved, stabilising the cell surface area

15

What is apocrine secretion?

- Non-membrane bound structure (eg lipid) approaches cell surface
- Makes contact and pushes up apical membrane
- Thin layer of apical cytoplasm drapes around droplet
- Membrane surrounding droplet pinches off from cell
- Plasma membrane is now smaller
- Membrane added to regain original size

16

Give an example of an apocrine gland

- Mammory glands

17

What test is used for cystic fibrosis and why?

- Sweat-testing for abnormally salty sweat
- Sweat is rich in sodium and chloride ions as the CFTR molecule is absent, so chloride ion reabsorption is poor in ducts of sweat glands

18

What is Holocrine secretion?

- Cell disintegrates
- Contents are released
- Whole cell is discharged

19

Give an example of a Holocrine gland

- Sebaceous glands

20

What is endocytosis

- Engulfing of material initially outside the cell

21

What is transepithelial transport?

- Endocytosis and exocytosis combined
- Material is endocytosed at one surface
- Transport vesicles shuttle across cytoplasm
- Material exocytosed at opposite surface

22

Describe the structure of the Golgi Apparatus

- Stack of disc-shaped cisternae
- One side of the discs are flattened, the other concave
- Discs have swellings at their edges (budding vesicles)
- Swellings pinch off as migratory Golgi Vacuoles

23

Where does glycosylation take place in the Golgi apparatus?

- Cisternae

24

Describe the function of the Golgi Apparatus

- Sorting into different compartments
- Packaging through condensation of contents
- Glycosylation (adding sugars to proteins and lipids)
- Transport of vesicles

25

What is the Destination of Golgi products?

- Majority given out in secretory vesicles
- Some retained for use in the cell (eg lysosomes)
- Some enter the plasma membrane (glycocalyx)

26

How does glycosylation affect specificity and how is the specificity reduced?

- Branching sugars offer complex shapes for specific interactions in the glycocalyx
- Sugars make the molecules more specific
- Enzymatic destruction of this layers alters specificity based properties of cells, such as: adhesion to substrates and neighbouring cells; communication with neighbouring cells; contact inhibition of movement and division; mobility of cells

27

How is secretion controlled?

- Nervous
- Endocrine control
- Neuro-endocrine control
- Negative feedback chemical mechanism

28

Give an example of nervous control of secretion

- sympathetic nervous stimulation of adrenal medullary cells leads to release of adrenaline

29

Give an example of endocrine control of secretion

- Adrenocorticotrophic hormone (ACTH) stimulates the cortex of the adrenal gland to secrete hormones eg cortisol

30

Give an example of neuro-endocrine control of secretion

- Nervous cells of the hypothalamus control ACTH secretion from the anterior pituitary gland

31

Give an example of how a negative feedback chemical mechanism controls secretion

- High thyroxine (T3 and T4) levels have an inhibitory effect on thyroid stimulating hormone (TSH) synthesis by the anterior pituitary gland

32

What is the effect of cystic fibrosis on the pancreas?

- Secretions of the exocrine pancreas block the ducts as they contain too little water and are too thick - becomes painfully inflamed (pancreatitis) and fibrotic
- The gut receives insufficient pancreatic digestive enzyme and malabsorption occurs
- Insufficient lipase production causes the faecal excretion of i digested fat, usually as diarrhoea

33

What is the effect of cystic fibrosis on the gastrointestinal tract?

- Lack of CFTR also occurs in the gastrointestinal tract causing constipation and invagination of the GI tract in older CF sufferers and in newborns can cause meconium ileus (inability to pass first faeces)

34

Give examples of exocrine glands

- Goblet cells in jejunum and colon
- Parotid glands
- Submandibular glands

35

Give examples of endocrine glands

- Pancreas
- Thyroid gland
- Parathyroid glands
- Adrenal glands

36

What are mucous membranes and where are they found?

- Line internal tubes that open to the exterior:
- Respiratory tract
- Alimentary tract
- Urinary tract

37

What do mucous membranes consist of?

- Epithelium (with basement membrane)
- Lamina propria (connective tissue with blood vessels and lymphatics)
- Muscularis Mucosae (smooth muscle) in alimentary tract

38

What are serous membranes (serosa) and where are they found?

- 2 part membrane that line some body cavities and envelope the viscera (internal organs)
- Pericardium
- Pleurae
- Peritoneum

39

What do serous membranes consist of?

- Simple squamous epithelium (mesothelium) which secretes a lubricating fluid into the cavity between the 2 layers
- Thin layer of connective tissue which contains neurovascular structures

40

What layers are in the gut?

- Mucosa
- Submucosa
- Muscularis external
- Serosa

41

What is the mucosa layer made up of?

- Epithelium
- Lamina propria
- Muscularis Mucosae

42

What does the Submucosa layer consist of?

- Connective tissue
- Glands
- Arteries and veins
- Nerves

43

What does the Muscularis externa of the gut wall consist of?

- 2 layer of smooth muscle: internal circular layer, outer longitudinal layer

44

What layers are in the oesophagus?

- Mucosa
- Submucosa
- Muscularis externa
- Adventitia

45

What layers are in the stomach?

- Gastric mucosa in rugae
- Muscularis Mucosae
- Submucosa
- Muscularis externa

46

How is the gastric mucosa different to normal mucosa?

- Secretes acid, digestive enzymes and gastric hormone
-Arranged in rugae - folded in longitudinal ridges in empty crease

47

What does the Muscularis externa in the stomach consist of?

- 3 layers of smooth muscle: oblique, circular and longitudinal

48

What layers are in the jejunum?

- Jejunal mucosa ) Arranged in plicae circularaes: circular folds of
- Submucosa ) mucosa and Submucosa projected into gut lumen
- Muscularis externa (2 layers)

49

What layers are in the large intestine (colon)?

- Mucosa (containing crypts of Lieberkühn and payer's patches)
- Submucosa
- Musculais externa

50

What are the layers in the trachea?

- Epithelium
- Lamina Propria
- Smooth muscle (with glands)
- C-shaped Hyaline cartilage
- Adventitia

51

What are the layers in the bronchus?

- Epithelium
- Smooth muscle
- Submucosa (with glands)
- Crescent shaped Cartilage

52

What are the layers in a bronchilole?

- Epithelium
- Smooth muscle
- Alveoli

53

What makes up alveoli?

- Type 1 squamous cells - with capillaries and allow gaseous exchange
- Type 2 cuboidal cells - produce surfactant
- Macrophages line alveolar surface
- Are surrounded by a basket work of capillaries and elastic fibres

54

What layers are in the ureter?

- Transitional epithelium
- Fibroelastic Lamina propria
- Circular Muscularis externa

55

What layers are in the bladder?

- Transitional epithelium (Impermeable to urine because of thick plasma membrane and tight intercellular junctions)
- Smooth muscle
- Musularis externa (3 interwoven layers)

56

What layers are in the urethra?

- Transitional epithelium
- Lamina propria
- Muscularis externa (2 layers: circular and longitudinal)
- Adventitia

57

Give an example of a simple tubular gland

- Intestinal glands

59

Give an example of a simple coiled tubular gland

- Merocrine sweat glands

61

- Give examples of simple branched tubular glands

- Gastric glands
- Mucous glands of the tongue, oesophagus and duodenum

63

Give an example of simple branched alveolar glands

- Sebaceous glands

63

Give examples of compound tubular glands

- Mucous glands in mouth
- Bulbourethral glands in male reproductive system
- Testes (seminiferous tubules)

63

Give an example of compound alveolar glands

- Mammary glands

63

Give examples of compunction tubuloacinar glands

- Salivary glands
- Glands of respiratory passages
- Pancreas