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Flashcards in Session 2 Deck (64):

Define gland

- An epithelial cell or collection of cells specialised for secretion


What is an exocrine gland?

- Ducts with glands


What is an endocrine gland?

- A ductless gland that secretes directly into the bloodstream


How can glands be classified?

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


How are glands classified by structure?

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


Give an example of a unicellular gland

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


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


Give an example of an Acinar/alveolar gland

- Pancreatic exocrine acinar cells


What is the difference between simple and compound glands?

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


How are glands classified by nature of secretion?

- Mucous or serous glands


What is a mucus gland?

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


What is a serous gland?

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


What are the major salivary gland?

- Parotid
- Submandibular
- Sublingual


How are glands classified by method of secretion?

- Merocrine
- Apocrine
- Holocrine


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


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


Give an example of an apocrine gland

- Mammory glands


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


What is Holocrine secretion?

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


Give an example of a Holocrine gland

- Sebaceous glands


What is endocytosis

- Engulfing of material initially outside the cell


What is transepithelial transport?

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


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


Where does glycosylation take place in the Golgi apparatus?

- Cisternae


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


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)


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


How is secretion controlled?

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


Give an example of nervous control of secretion

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


Give an example of endocrine control of secretion

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


Give an example of neuro-endocrine control of secretion

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


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


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


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)


Give examples of exocrine glands

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


Give examples of endocrine glands

- Pancreas
- Thyroid gland
- Parathyroid glands
- Adrenal glands


What are mucous membranes and where are they found?

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


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


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


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


What layers are in the gut?

- Mucosa
- Submucosa
- Muscularis external
- Serosa


What is the mucosa layer made up of?

- Epithelium
- Lamina propria
- Muscularis Mucosae


What does the Submucosa layer consist of?

- Connective tissue
- Glands
- Arteries and veins
- Nerves


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

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


What layers are in the oesophagus?

- Mucosa
- Submucosa
- Muscularis externa
- Adventitia


What layers are in the stomach?

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


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


What does the Muscularis externa in the stomach consist of?

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


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)


What layers are in the large intestine (colon)?

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


What are the layers in the trachea?

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


What are the layers in the bronchus?

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


What are the layers in a bronchilole?

- Epithelium
- Smooth muscle
- Alveoli


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


What layers are in the ureter?

- Transitional epithelium
- Fibroelastic Lamina propria
- Circular Muscularis externa


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)


What layers are in the urethra?

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


Give an example of a simple tubular gland

- Intestinal glands


Give an example of a simple coiled tubular gland

- Merocrine sweat glands


- Give examples of simple branched tubular glands

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


Give an example of simple branched alveolar glands

- Sebaceous glands


Give examples of compound tubular glands

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


Give an example of compound alveolar glands

- Mammary glands


Give examples of compunction tubuloacinar glands

- Salivary glands
- Glands of respiratory passages
- Pancreas