Lecture 7 - Glands Introduction

Question 1

What is the definition of a gland?

Answer 1

An epithelial cell or an aggregate o epithelial cells that are specialised for the secretion of a substance

Question 2

What is a secretion?

Answer 2

The production and release of materials by a cell or aggregate of cells

Question 3

Give an example of a single celled gland and name its secretion:

Answer 3

Goblet cell
Mucin

Question 4

What is an endocrine gland?

Answer 4

A gland that secretes directly into the blood allowing the secretion to act at distant parts of the body

Question 5

What are the secretions called that are released from endocrine glands?

Answer 5

Hormones

Question 6

Give some examples of endocrine glands and their hormones:

Answer 6

Hypothalamus - TRH, CRH, GnRH, GHRH, GHIH, PRH
Anterior pituitary - ACTH, LH, FSH, TSH, Prolactin, GH
Posterior pituitary - ADH and Oxytocin
Thyroid gland - T3, T4 and Calcitonin

Question 7

What type of cell are all of the cells in endocrine glands?

Answer 7

Simple cuboidal cells

Question 8

What are exocrine glands?

Answer 8

Glands that release their secretions through ducts into a location or region of the body

Question 9

What are the secretions from exocrine glands usually?

Answer 9

Enzymes
Lubricants

Question 10

Give some examples of exocrine glands and their secretions:

Answer 10

Salivary gland
Pancreas (amylase, Lipase and trypsin)
Sweat glands
Sebaceous glands (sebum)
Lachrymose glands (fluid and lysozyme tears)

Question 11

What is adenogenesis?

Answer 11

Gland formation
Adeno = Gland
Genesis = formation

Question 12

Describe adenogenesis of an endocrine gland:

Answer 12

FGF Growth signal received
Proliferation of epithelial cells occurs and grows downwards into connective tissue
Extracellular protein degradation enzymes produced
Angiogenic factors made to stimulate blood vessel growth around epithelial cells
Extracellular protein degradation enzymes kill cells at stalk causing the stalk to break off

Separated aggregation of cells made

Question 13

Describe adenogenesis of an exocrine gland:

Answer 13

FGF growth signal received
Proliferation of epithelial cells occurs and grows downwards into connective tissue
Extracellular protein degradation enzymes produced
Central cells die of to produce duct (CANALICULARISATION)
Significant amount of branching occurs

Question 14

How does branching occur?

Answer 14

Alternate activation or unequal activation of Growth Factor 1 and Growth factor 2

Question 15

What does Growth factor 1 stimulate when active?

Answer 15

Tubule elongation

Question 16

What does Growth factor 2 stimulate when active?

Answer 16

Tubule branching

Question 17

In exocrine glands, which cells release the secretions?

Answer 17

Cells at the Apex of the duct

Question 18

What is the name give to the functional cells at the apex of the duct in exocrine glands?

Answer 18

Parenchyma cells

Question 19

What are myoepithelial cells?

Answer 19

Cells in exocrine glands that have features of an epithelial cell and smooth muscle cell

Question 20

What is the function of a myoepithelial cell?

Answer 20

To help eject secretions from exocrine ducts

Question 21

What do myoepithelial cells do?

Answer 21

Help eject secretions from exocrine ducts

Question 22

What are the 2 types of Simple tubular duct?

Answer 22

Simple tubular
Simple branched tubular

Question 23

Where can an example of a simple tubular duct be found?

Answer 23

Intestinal glands

Question 24

Where can an example of a simple branched tubular duct be found?

Answer 24

Stomach glands (make HCl)

Question 25

What are the 2 types of Simple Alveolar ducts?

Answer 25

Simple alveolar Simple branched alveolar

Question 26

Where can an example of a simple alveolar duct be found?

Answer 26

NONE IN HUMANS

Question 27

Where can an example of a simple branched alveolar duct be found?

Answer 27

Sebaceous glands

Question 28

Where can a Compound Tubular duct be found?

Answer 28

Duodenal glands of small intestine

Question 29

What are the 2 types of compound alveolar ducts?

Answer 29

Compound alveolar Compound tubuloalveolar

Question 30

Where can an example of a compound alveolar gland be found?

Answer 30

Mammary glands

Question 31

Where can an example of a Compound tubuloalveolar gland be found?

Answer 31

Salivary glands

Question 32

What does alveolar mean?

Answer 32

Berry shaped

Question 33

What does striated mean?

Answer 33

Striped

Question 34

What does demilune mean?

Answer 34

Half moon

Question 35

What does intercalating mean?

Answer 35

Inserts between

Question 36

What does acinus mean?

Answer 36

Sac like or alveolar

Question 37

What are the 3 types of secretion?

Answer 37

Merocrine Apocrine Holocrine

Question 38

What is merocrine secretion?

Answer 38

Fusion of vesicles with the apical membrane (A form of exocytosis)

Question 39

What is Apocrine secretion?

Answer 39

Partial loss of the cytoplasm (A portion of the cell is pinched off and lost) APical surface is lost

Question 40

What is Holocrine secretion?

Answer 40

Complete loss of the cytoplasm so cell dies

Question 41

What are the 2 types of merocrine secretion?

Answer 41

Regulated Constitutive

Question 42

How does regulated merocrine secretion work?

Answer 42

Cargo accumulates in large vesicles Vesicles released by exocytosis upon stimulation from Ca2+ ions

Question 43

How does constitutive merocrine secretion work?

Answer 43

Secretory product packaged into small vesicles which are continuously released to the cells surface Repopulates plasma membrane with plasma proteins

Question 44

What is a drug which can help treat diabetes by acting on beta cells?

Answer 44

Sulphonyl urea

Question 45

How does the drug sulponyl urea act to help treat diabetes?

Answer 45

It binds to sulphoyl urea receptor on ATP sensitive K+ ion channel on Beta cell causing it to close without the need for increased glucose Cell depolarises Ca2+ voltage gated ion channel opens Calcium influx Insulin released via regulated merocrine secretion

Question 46

During lactation, what are secreted by apocrine secretion?

Answer 46

Fats Proteins

Question 47

Where does Holocrine secretion take place?

Answer 47

Sebaceous gland

Question 48

Briefly describe how Holocrine secretion works:

Answer 48

Cell fills up with secretory granules Organelles and cell dies Plasma membrane breaks and cell contents released Dead cells replaced by basal cells

Question 49

What is the role of the Golgi apparatus in secretion?

Answer 49

It packages and processes proteins in regulated or constitutive pathway of merocrine secretion

Question 50

Which face does a protein enter the Golgi and then leave the Golgi?

Answer 50

Enters = Cis face Leaves = Trans face

Question 51

What often happens to a protein as it travels from the cis face (convex) through to the trans face (concave) of the Golgi?

Answer 51

Glycosylation

Question 51

What often happens to a protein as it travels from the cis face (convex) through to the trans face (concave) of the Golgi?

Answer 51

Glycosylation

Question 52

What is the definition of glycosylation?

Answer 52

The covalent attachment of sugars by ENZYMES to proteins and lipids to form glycoproteins and glycolipids

Question 53

What is the definition of Glycation?

Answer 53

Covalent attachment of sugars to proteins and lipids WITHOUT ENZYMES

Question 54

What is the purpose of glycosylation of lipids and proteins in the Golgi?

Answer 54

Prevent destruction by enzymes (Intracellular proteases and lipases) Aids protein folding Cell recognition Cell to extracellular matrix attachment (proteoglycans)

Question 55

What is exocytosis?

Answer 55

Secretion/release of molecules outside the cell via a vesicle fusing to a membrane

Question 56

What is endocytosis?

Answer 56

Engulfing of molecules inside the cell via vesicle formation

Question 57

What are the 2 types of endocytosis?

Answer 57

Phagocytosis Pinocytosis

Question 58

What is phagocytosis?

Answer 58

The process by which cells (phagocytes) engulf other cells or particles

Question 59

What is pinocytosis?

Answer 59

The process by which liquid droplets are ingested by cells Used in all cells especially smooth muscle cells

Question 60

What is transepithelial transport?

Answer 60

The directed movement of a substance from one side of epithelium to another

Question 61

How does transepithelial transport use paracellular transport?

Answer 61

Molecules can diffuse through channels between cells called gap junctions (they clap open and closed)

Question 62

How does transepithelial transport use trancellular transport?

Answer 62

Molecules diffuse through lipid cell membranes

Question 63

How does transepithelial transport use carrier proteins?

Answer 63

Molecules can bind to carrier proteins which can by transported into then out of the epithelial cell

Question 64

How does transepithelial transport allow impermeable molecules to be transported through the epithelial cells?

Answer 64

BInd to cell surface receptor Receptor mediated endocytosis Then expelled in vesicle via exocytosis

Question 65

Which molecules are transported via paracellular transport?

Answer 65

Amino acids (hormone production)

Question 66

Which molecules travel via trans cellular transport?

Answer 66

Steroid hormones

Question 67

Which molecules travel via carrier proteins across epithelial cells?

Answer 67

Thyroxine transport across thyroid follicular cell

Question 68

Which molecule uses receptor mediated endocytosis then exocytosis to travel?

Answer 68

Cholesterol

Question 69

What are the 3 negative feedback systems which regulate hormone release?

Answer 69

Hormonal Neuronal Humoral

Question 70

What is humoral regulation for hormone release?

Answer 70

Changes of the levels of something in the blood that is not a hormone stimulates/regulates the release of secretions from glands

Question 71

Give an example of a gland under humoral control and state its humoral stimulus:

Answer 71

Parathyroid gland Blood Ca2+ levels Releases PTH to increase blood Ca2+ levels

Question 72

What is neurocrine communication?

Answer 72

When a hormone originates in a neurone and is then secreted by the neurone

Question 73

Where doe neurocrine secretion/communication take place?

Answer 73

Neurones originating in hypothalamus synthesise ADH and oxytocin which travels to the posterior pituitary for storage

Question 74

What is the name of the portal system which hormones produced by the hypothalamus are released into to affect the anterior pituitary gland?

Answer 74

Hypothalamo-hypophyseal portal system