Glands Flashcards
(147 cards)
1
Q
Define a gland
A
an epithelial cell or an aggregate of epithelial cells that are specialised for secretion of a substance
2
Q
Define secretion
A
the production and release of materials by a cell or aggregate of cells
3
Q
How are glands classified
A
by their structure
by how their products are released
4
Q
what are the two types of structures of glands
A
- endocrine
- exocrine
5
Q
what are the 3 different ways exocrine glands release their products
A
- merocrine
- apocrine
- holocrine
6
Q
What is the difference between exocrine and endocrine glands
A
- endocrine (ductless)
secreted directly into blood to travel to distant parts of the body
secrete hormones only - exocrine (ducted)
secrete through a duct
secrete only enzymes or proteins
only cells at the apex on duct secrete
7
Q
Give examples of endocrine glands
A
- thyroid
- parathyroid
- pituitary gland
8
Q
give examples of exocrine glands
A
- salivary glands
- mammary
- sweat glands
- lacrimal glands
9
Q
what is adenogenesis
A
in utero development of glands
10
Q
describe the process of adenogenesis before specialisation of glands
A
1) growth signal received (FGF family member)
2) proliferation of cells occurs and extracellular protein degradation enzyme produced (creates space)
3) epithelial cells invade space created
4) specialisation
11
Q
How do exocrine glands specialise
A
EXOCRINE
central cells die off to produce duct (canalicularisation)
still linked to mother cell
lots of branching
12
Q
How do endocrine glands specialise
A
ENDOCRINE
produce angiogenic factors to stimulate blood vessel growth
link to mother cells broken through apoptosis
no branching
13
Q
how do exocrine glands branch
A
- FGF10 released by immature fibroblasts (mesenchymal stem cells )
- epithelial cells move towards signal
- two fates:
tubule elongation
tubule branching
14
Q
Which growth factor is active and which one is inactive in tubule elongation
A
Growth factor 1 active
Growth factor 2 inactive
15
Q
Which growth factor is active and which one is inactive in tubule branching
A
Growth factor 1 inactive
Growth factor 2 active
16
Q
What is elongation and branching stopped by
A
Shh
17
Q
what are the different shapes of exocrine glands
A
- simple tubular
- simple tubular branched
- simple alveolar
- simple branched alveolar
- compound tubular
- compound alveolar
- compound tubuloalveolar
18
Q
what is the difference between a simple duct structure and compound duct structure
A
simple ducts do not branch whil compound ducts branch
19
Q
where are simple tubular ducts found
A
intestinal glands
20
Q
where are simple branched tubular found
A
stomach glands
21
Q
where are simple alveolar found
A
not in humans
22
Q
where are simple branched alveolar found
A
sebaceous oil glands
23
Q
where are compound tubular glands found
A
dudodenal glands of small intestine
24
Q
where are compound alveolar ducts found
A
mammary glands
25
where are compound tubuloalveolar glands found
salivary glands
26
how many salivary glands are there
3
27
what type glands are found in salivary glands
compound tubuloalveolar glands
28
what are the two types of secretions found in salivary glands
mucus
serous
29
what are myoepithelial cells
secretory ends of ducts that have features of smooth muscle and epithelial cells
help eject secretions from duct
30
what is the smallest duct in salivary glands
intraobular duct
31
what is the second smallest duct in salivary gland
intercalated duct
32
what is the third size duct in salivary glands
striated duct
33
what is the largest duct in salivary gland
excretory duct
34
describe merocrine secretion and give an example
fusion of vesicles with membrane so no damage to cell a form of exocytosis
example: acinar and endocrine glands of pancreas
35
describe apocrine secretion and give an example
partial loss of cytoplasm
example: lactating mammary glands
sweat glands in axilla
36
describe holocrine secretion and give an example
complete loss of cytoplasm
example sebaceous glands in skin or tarsal glands in eyelid
37
what is cytocrine secretion
cells released as a secretion
38
what are the two types of secretion pathways of merocrine
- regulated secretion
- constitutive secretion
39
what is the regulated secretion pathway of merocrine secretion
- secretory granules accumulate in large vesicles
- vesicles released out of cell surface when signal arrives (Ca 2+ ions)
- cargo released into extracellular space
- active process
40
what are the contents of vesicles called
cargo
41
what is the constitutive secretion pathway of merocrine secretion
- secretory product not concentrated into small granules but packaged into small vesicles
- small vesicles continuously released to cell surface
42
give an example of regulated merocrine secretion
insulin release in pancreas
43
give an example of apocrine secretion
the breast
44
give an example of holocrine secretion
sebaceous gland
45
describe the merocrine secretion of insulin
- glucose metabolised in cell mitochondria making ATP
- ATP stimulates ATP sensitive K+ channel which moves K+ out of cell making inside more negative
- causes calcium channel to move Ca2+ ions to move in
- Ca2+ signal vesicles to fuse with mem
46
describe apocrine secretion of milk breasts
- neonatal period : only fats secreted by apocrine
- milk proteins made in RER and packaged into vesicles by golgi released by merocrine secretion
- during lactation:
both fats and proteins are released by apocrine secretion
47
what is exocytosis
secretion of molecules outside the cell via a vesicle fusing to mem
48
what is an example of exocytosis
formation of ion channels in kidney
49
what is endocytosis
engulfing of molecules inside the cell via vesicle formation
50
what is an example of endocytosis
endothelium
smooth muscle cells
adipose tissues
51
what is phagocytosis and what cells use it
process by which cells envelop or engulf other cells or particles
used by phagocytes or immune system cells
52
what is pinocytosis
the process by which liquic droplets are ingested by cells especially smooth muscle
53
what is the role of the Golgi apparatus
- proteins containing vesicles from RER transfer substance to cis face of golgi
- golgi chemically modified protein in its lumen
- targets them to correct address leaving trans face
54
what is glycosylation
the covalent attachment of sugars by enzymes to proteins and lipids to form glycoproteins ad glycolipids
55
what are the roles of glycosylation
- aid protein folding
- prevents protein and lipids digestion by intracellular proteases and lipases
- cell recognition
- role on cell to extracellular matrix attachment
56
what are the four types of transepithelial transport
- paracellular
- transcellular
- carrier proteins
- endocytosis and exocytosis
57
what is paracellular transport
molecules move by passive diffusion through aqueous channels in the intercellular junction
58
what is transcellular transport
molecules move through lipid cell membranes
59
what is carrier protein transport
molecules are transported by carrier proteins into or out of the cells or by a counter transport process
60
what are the three types of regulation of secretion
- hormonal
- neural
- humoral
61
how does hormonal regulation regulate secretion
peripheral endocrine glands products inhibit hypothalamus and anterior pituitary gland
62
how does neural regulation regulate secretion
the action produced inhibit nervous system
63
how does humoral regulation regulate secretion
the action inhibits changing substance of in plasma levels
64
what is a hormone
a chemical messenger produced by endocrine glands
released into bloodstream where they travel to target organs to regulate various processes
65
where are endocrine tissues mainly found and what is the exception
mainly found in head and core due to 37 body temp other than testes which are external are prefer lower temp
66
what are the two areas of the pituitary gland
anterior
posterior
67
what hormones do the anterior pituitary gland secrete
TSH
ACTH
FSH
LH
GH
PRL
MSH
68
what hormones do the posterior pituitary gland release
vasopressin (ADH)
oxytocin
69
where is the pituitary gland located
base of brain below hypothalamus
70
where is the thyroid gland located
anterior to trachea
71
what hormones do thyroid glands release
thyroxine T4
triiodothyronine T3
72
where is the parathyroid gland located
dorsal surface of the thyroid gland (4 in 2 pairs)
73
what hormone does the parathyroid gland release
parathyroid hormone PTH
74
where are the adrenal glands located
top of the superior poles of kidneys
75
what hormones do the adrenal glands release
medulla- catecholamines (adrenaline, noradrenaline, dopamine)
cortex- corticosteriods,
glucocorticoids (cortisol, cortisone)
mineralocorticoids (aldosterone)
androgenic steroid hormone precursors
76
what are the four types of hormones
- glycoproteins/ peptide hormones
- steroid hormones
- amino acid derived hormones
- lipid hormones
77
what are the two types of amino acid derivative hormones
catechloamines
thyroid hormones
78
how are glycoprotein/peptide hormones synthesised and stored
made in advance
stored in secretory vesicles
79
how are amino acid derivative hormones synthesised and stored
made in advance
stored in secretory vesicles
80
how are steroid hormones synthesised and stored
synthesised on demand from precursors
81
how are lipid hormones synthesised and stored
synthesised on demand from precursors
82
how are glycoprotein/peptide hormones transported in blood
dissolved in plasma
83
how are steroid hormones transported in blood
bound to carrier proteins
84
how are catecholamine hormones transported in blood
dissolved in plasma
85
how are thyroid hormones transported in blood
bound to carrier proteins
86
how are lipid hormones transported in blood
dissolved in plasma and bound to carrier proteins
87
where is the location of the receptors for glycoprotein and peptide hormones
cell membrane
88
where is the location of the receptors for steroid hormones
cytoplasm or nucleus
89
where is the location of the receptors for catechloamine hormones
cell membrane
90
where is the location of the receptors for thyroid hormones
nucleus
91
where is the location of the receptors for lipid hormones
cell membranes
92
what is the response to glycoprotein/peptide hormones binding to receptors
activation of second messenger pathway and may activate gene expression
93
what is the response to steroid hormones binding to receptors
activation of genes for transcription
94
what is the response to catehloamines hormones binding to receptors
activation of second messenger systems
95
what is the response to thyroid hormones binding to receptors
activation of genes for transcription
96
what is the response to lipid hormones binding to receptors
cell membrane
97
give examples of glycoproteins/peptide hormones
insulin, glucagon, prolactin, ACTH, PTH
98
give examples of steroid hormones
oestrogen, androgens, progesterone
cortisol
99
give examples of catechloamines hormones
adrenaline, noradrenaline, dopamine
100
give examples of thyroid hormones
thyroxine T4
triiodothyronine T3
101
give examples of lipid hormones
thromboxanes
prostaglandins
endocannabinoids
102
what is the embryological origin of endocrine glands
during development epithelial tissues fold inwards or pinch off from epithelial layers to form glandular structures
103
where does the thyroid gland develop from
develops from epithelial outgrowth of pharynx
104
where do adrenal glands develop from
originate from the mesodermal epithelium and neural crest
105
where does the pituitary gland develop from
develops from two epithelial derived structures
- oral ectoderm
- neural ectoderm
106
how do endocrine glands transform from exocrine glands
endocrine glands loose their ducts during development
- as epithelial cells loose their ducts by the duct cells regressing which leaves a cluster of hormone secreting cells surrounded by a rich network of blood vessels
107
how do exocrine glands structurally change to form endocrine glands
loose ducts
cells arrange themselves into cords or clusters surrounded by capilaires to facilitate rapid hormone secretion into blood
108
what are the hypothalamus and pituitary gland know as
master gland
109
what does the hypothalamus deal with
- thermoregulation
- plasma osmolality
- heart rate and bp
- reg of GI
- circadian rhythms
- ANS
- emotion
- lactation
110
what does the hypothalamus produce
- vasopressin ADH
- oxytocin
111
how are the hypothalamus and pituitary gland connected
hypothalamo-hypophyseal portal system
- six hormones travel through this portal system to anterior pituitary where they are then released
112
why is there always a small concentration of pituitary hormones in the blood
all pituitary hormones are all subject to constitutive and regulated merocrine secretion
113
what is the difference between anterior and posterior pituitary lobes
neurones that produce hormones released from posterior pituitary lobe extend whole pituitary stalk while anterior neurones do not extend into the lobe
114
what cells is the thyroid gland made up of
consists of follicles made up of principal cells that secrete thryoglobulin which is precursor to thyroid hormones
114
what is a portal system
blood passes through two sets of smaller vessels before returning to the heart
115
what do principal cells do
- principal cells secrete thyroglobulin into colloids
- transport iodide for iodination
- produce T3 and T4 hormones through series of enzymatic reactions
116
what are colloids
storage of large amounts of inactive hormone within extracellular components
117
how is calcium regulated by C cells
C cells are parafolicular cells that regulate serum calcium levels by secreting calcitonin which inhibits osteoclast activity (cells that help bones develop)
- calcitonin release stimulated by high calcium levels and inhibited by low calcium
118
what is the difference between T4 and T3 hormones
T4 is tetriodothryonine 90% of output
T3 is triiodothyronine
T3 is more biologically active
T4 converted to T3 in peripheral tissues by the enzyme deiodinase
119
how does T3 regulate metabolism
promotes thermogenesis by increasing uncoupling proteins in mitochondria which generates heat instead of ATP
120
how do T4 and T3 hormones provide feedback
provide negative feedback on hypothalamus and pituitary gland to regulate their own production
- they inhibit TRH synthesis in hypothalamus and reduce TRH receptors in pituitary lowering TSH release
121
what type of cells are found in parathyroid glands
chief cells
122
what do chief cells produce
chief cells produce parathyroid hormone PTH
123
124
what does parathyroid hormone do
regulates calcium metabolism in the body
- when serum calcium levels drop PTH released stimulating osteoblasts to produce proteins like RANKL
-that promote the formation of osteclasts leading to bone degradation so calcium release
125
how does the parathyroid gland sense calcium
chief cells have a calcium sensing receptor (G coupled protein receptor) that regulates PTH secretion based on serum calcium levels
126
what are oxyphilic cells
large mitochondria rich cells are present in parathyroid
function unknown
127
why are the adrenal glands known as mixed glands
have both endocrine and neuroendocrine glands
128
what is the plexus
large capillary network which does down from cortex down to medulla where substances are released from
129
what are the behavioural changes in response to adrenaline
increased awareness
improved cognition
euphoria
enhanced analgesia
130
what are the physiological adaptations in response to adrenaline
increased cardiovascular tone
increased respiratory rate
increased intermediate metabolism
decreased vegetative functions
131
what is the adrenal medulla comprised of
composed of parenchyma (functional part) of large pale staining epitheloid cells called chromaffin cells
132
what are chromaffin cells
modified neurones
release catechloamines adrenaline and noradrenaline stimulated by nerve impluses
- chromaffin cells considered post synaptic neurones
133
what are the three layers of the adrenal cortex
- zona glomerulosa (outer)
- zona fasciculta (middle)
- zona reticularis (end)
134
what does the zona glomerulosa secrete
aldosterone which regulates blood pressure
135
what does the zona fasciculata secrete
glucocorticoids (cortisol)
which metabolises fats, proteins and carbs
136
what does the zona reticularis secrete
androgen precursors like DHEA, androstenedione
137
how does the hypothalamus communicate with the adrenal glands
through sympathetic preganglionic neurones
hypothalamus releases cortioctrophin releasing hormone which stimulates pituitary gland to release ACTH which binds to adrenal receptors
138
why does the hypothalamus need to communicate with adrenal glands
faster for flight or fight response
139
describe the structure of the pancreatic glands
- acinar gland (sac like)
- grouped into lobules
- contain numerous zymogen granules
- connect through numerous intercalated ducts (lined with cuboidal epithelial cells) to pancreatic ducts which joins with bile duct
140
why is the pancreas unique in terms of glands
have both exocrine and endocrine glands
141
what are the endocrine glands in the pancreas
islet of Langerhans
142
what are the exocrine glands in the pancreas
acini
143
what do alpha cells in the islets of langerhans release
glucagon
144
what do beta cells in the islets of langerhans release
insulin
145
what do delta cells in the islets of langerhans release
somatostatin
146
