Principles of Endocrinology Flashcards
(75 cards)
1
Q
Name the hormone-secreting glands of the human body.
A
Thyroid - Schilddrüse
Adrenals - Nebennieren
Ovaries - Eierstöcke
Testes - Hoden
Pancreas - Bauchspeicheldrüse
Pituitary - Hypophyse
2
Q
Name a hormone which is secreted by the thyroid.
A
Thyroxin (T4)
3
Q
Name a hormone which is secreted by the adrenals.
A
Cortisol
4
Q
Name a hormone which is secreted by the ovaries.
A
Estradiol
5
Q
Name a hormone which is secreted by the testes.
A
Testosteron
6
Q
Name a hormone which is secreted by the pancreas.
A
Insulin
7
Q
Name a hormone which is secreted by the pituitary.
A
ACTH
8
Q
Is leptin a hormone or a mediator? Give reasons for your answer.
A
Leptin is a mediator, because it serves as a messenger substance within the body, but it is not produced by an secreting gland.
9
Q
Where is leptin produced?
A
In adipose tissue
10
Q
Which kind of organs are part of the “diffuse” endocrine system?
A
Organs, which are not secreting glands but can produce mediators, which work similar to hormones.
11
Q
Name five organs of the “diffuse” endocrine system and for each one mediator which is produced.
A
Brain - Oxytocin
Stomach - Ghrelin
Heart - ANP(H)
Liver - Erythropoietin
Muscle - Irisin
12
Q
Name four groups of hormone-like mediators that are not hormones.
A
- Neurotransmitters (synaptic transmission)
- Cytokines (immune modulators)
- Prostaglandines and thromboxanes
- Pheromones (into the environment excreted signaling molecules)
13
Q
What is endocrine and exocrine secretion?
A
- Endocrine: Secretion into the blood
- Exocrine: Secretion into environment connected to the outside (gut, skin, oral cavity)
14
Q
What does it mean, if hormones are working paracrine or autocrine?
A
- Paracrine: local action on neighboring cells
- Autocrine: local action on the secreting cell
15
Q
Name four hormonal regulation tasks.
A
Regulation of
- cell membrane permeability
- intracellular enzyme activity
- gene expression
- cell proliferation and cell death
16
Q
Name two ways on which hormones can act on target cells.
A
- They can enter the cell through the membrane (mainly lipophilic hormones)
- They can bind to cell membrane receptors (mainly peptide hormones)
17
Q
Which hormone classes exist?
A
- Protein/Peptide hormones
- Terpenes / Steroids in mammals
- Amino acid derivates
18
Q
Name four regulation tasks of protein/peptide hormones.
A
Regulation of
- reproduction
- glucose metabolism
- blood pressure
- other hormones and growth factors
19
Q
Name five regulation tasks of terpenes/steroids.
A
Regulation of
- reproduction
- stress response
- metabolism
- immunity
- skeletal formation
20
Q
Name four regulation tasks of amino acid derivates.
A
Regulation of
- metabolism
- stress response
- reward system
- sleep
21
Q
How does hormonal cell membrane receptor signalling work (very general) and which hormone classes use it?
A
It is used by peptide homones and amino acid derivates.
- Hormone is binding to a receptor on the cell membrane surface
- A signal is triggered intracellularly, which is passed on to the cell nucleus
22
Q
How does hormonal intracellular receptor signalling work (very general) and which hormone classes use it
A
It is used by terpenes and amino acid derivates.
- Hormones pass through the cell membran and bind intracellular to a receptor
- The bound receptor moves into the nucleus where it triggers a signal
23
Q
How do cell membrane receptor signalling and intracellular receptor signalling differ in terms of speed and the number of hormones required?
A
- cell membrane receptor signalling:
- fast signaling and response
- one hormone is usually enough for a significant effect - intracellular receptor signalling:
- slow signaling and response
-> The effects usually only occur after appropriate
transcription
- many hormones are required for a large effect
24
Q
Name the three parts of a nuclear receptor.
A
- DNA-binding domain
- Hinge (nuclear localisation signal)
- Lingand-binding domains
25
What are nuclear receptors?
Ligand-activated transcription factors
- They bind directly to the DNA
- They modulate the transcription of one or many target
genes
26
Describe the characteristics of type-1 nuclear hormone receptors.
- The inactive form is bound to heat-shock factors (HSPs) in cytoplasm
- Upon hormone binding, the receptor dissociates from HSP and often dimerize with another receptor
- The receptor/dimer translocates into the nucleus
- There the receptor binds to palindromic DNA motifs
27
What are the palindromic DNA motifs to which nuclear hormone receptors bind called?
Hormone response elements (HREs)
28
Describe the characteristics of type-2 nuclear hormone receptors.
- The inactive form is bound to DNA via Zinc-finger motif
- Upon hormone binding, corepressors are replaced by the
coactivator complex
- The transcription is initiated
- DNA-binding motif: AGGTCA
29
Name the main difference between type-1 and type-2 nuclear receptors.
- Type-1 NRs bind the hormone in the cytoplasm
- Type-2 NRs bind the hormone in the nucleus
30
Name one similarity and one difference between type-1 and type-3 nuclear receptors.
- Both types bind to DNA as homodimers
- Type-1 NRs bind to inverted repeat HREs
- Type-3 NRs bind to direct repeat HREs
31
Name two similarities and one difference between type-2 and type-4 nuclear receptors.
- Both types are found in the nucleus all the time
- Both bind either as monomers or dimers
- Thereby, only a single DNA-binding domain of the
receptor binds to a single half-site HRE
- The two types can differ in binding motifs or dimerization
partners
32
Name one example for each type of nuclear hormone receptors.
1. Type-1: Glucocorticoid receptor (Monodimer)
2. Type-2: Thyroid homone receptor
3. Type-3: Retinoid-X receptor
4. Type-4: NGFI-B receptor
33
There are two different structures of hormone response elements (HREs). What structures are these and what type of NR are they bound by?
1. Inverted repeats (AGAACA-TGTTCT)
- They are bound by type-1 NRs
2. Direct repeats (AGGTCA-AGGTCA)
- They are bound by type-2 and -3 NRs
34
Name six examples for NR ligands.
Retinoids
Fatty acids
Sterans
Heme
Vitamine D3
Thyroid hormones
35
Explane shortly how the principle of first and second messenger signaling with membrane-bound receptors is working.
- Hormones (first messenger) are binding to the membrane-
bound receptor
- Binding leads to structural changes in the cytoplasm
-> Activation of second messenger ()
- Second messenger activate a cascade of cellular responses
36
The nomenclature of cell membrane receptors is based on the first effector enymatic activity. Name five receptors that follow this nomenclature.
1. G-protein-coupled receptor (GPCR) - GTPase activity
2. Receptor tyrosine kinase (RTK) - Tyrosine kinase activity
3. Tyrosine kinase associated receptor (TKAR) - Tyrosine kinase activity
4. Receptor serine/threonine kinases (RS/TK) - Serine/threonine kinase activity
5. Guanylate cyclase-coupled receptor (GCCR) - Guanylate cyclase activity
37
Name three types of common second messenger molecules.
1. Lipophilic molecules
- They stay at the plasma membrane and act really fast
2. Hydrophilic molecules
- They are produced at the membrane and diffuse
afterwards
- They act more slowly than lipophilic molecules
3. Gaseous molecules
- They can cross cells and effect also neighboring cells
- They act the most slowly of these three types
38
Name two lipophilic molecules which are commonly acting as second messenger.
Diacyglycerol
Phosphatidylinositols
39
Name four hydrophilic molecules which are commonly acting as second messenger.
Ca 2+
IP3
cAMP
cGMP
40
Name three gaseous molecules which are commonly acting as second messenger.
NO
H2S
CO
41
Name four memo-phrases of intracellular signaling cascades.
1. cAMP activates protein kinase A (PKA) signaling.
2. Membrane-bound PIP3 activates PKB signaling.
3. Ca 2+ activates PKC signaling.
4. cGMP activates PKG signaling.
42
Name the six classes of G-protein coupled receptors (GPCRs).
1. Class: Rhodopsin-like receptors
2. Class: Secretin receptor family
3. Class: Metabotropic glutamate/pheromone receptors
4. Class: Fungal mating pheromone receptors
5. Class: Slime mould cyclic AMP receptors
6. Class: Frizzled/smoothened - Wnt signaling receptors
43
Name the three types of G-proteins.
1. G alpha-s/i
s-stimulate / i-inhibit
2. G alpha-q
3. G alpha-12/13
44
Describe the function of the glucagon receptor in connection with adenylate cyclase.
1. Glucagon binds to the glucagon
receptor (GCGR)
2. This activates G-s (stimulating G
protein)
3. G-s activates the adenyl cyclase
(AC)
4. AC converts ATP into cAMP
5. cAMP activates the protein
kinase A (PKA)
6. PKA phosphorylates target
proteins, leading to:
-> Glycogenolysis
-> Gluconeogenese
-> Increased blood glucose level
45
Describe the function of the glucagon receptor in connection with phospholipase C.
1. Glucagon binds to the glucagon
receptor (GCGR)
2. Under certain conditions this activates G-q
3. G-q activates the phospholipase C (PLC)
4. PLC cleaves PIP2 into IP3 and DAG
5. IP3 releases Ca 2+ from the ER
6. DAG activates PKC
The glucagon-PLC pathway supports the functions of the glucagon-AC pathway and also promotes an increase in blood glucose levels.
46
Which disease are GCGR mutations associated with?
Type-2 diabetes
47
In which three steps are receptor tyrosine kinases (RTKs) activated?
1. Extracellular ligand binding
2. RTK dimerization
3. Intracellular autophosphorylation
48
Name two main functions of the insulin receptor.
1. Regulation of growth via RAS and JNK
2. Regulation of metabolism via Akt/PKB
49
Name three common examples of receptor tyrosine kinases.
1. Insulin receptor
2. VEGFR
3. NGFR
50
What does the abbreviation JAK stand for?
Janus kinase
51
What does the abbreviation IRAK stand for?
Interleukin-1 receptor-associated kinase
52
Which hormone class do releasing and tropic hormones belong to?
Peptide hormones
53
Name five aspects which are regulated by peptide hormones.
1. Reproduction
2. Energy metabolism
3. Blood pressure
4. Growth
5. Appetite regulation
54
How are hormonal axis regulated in general?
Regulation via negative feedback
-> High hormone levels in the adrenals decrease the corresponding activity in the pituitary and the hypothalamus
55
What steps of post-translational modifications do peptides go through?
- Peptide cleavage
- Amidation
- Amino acid cyclization
- acylation
56
How are peptide hormones stored and released?
1. They are stored in vesicles
2. They are released via regulated exocytosis
-> Either to exit the cell
-> Or to enter into the Golgi network
57
Where in the human body are most peptide hormones found?
Circulating freely in the blood
58
How long is the half-life of peptide hormones and how are they degraded?
-> Their half-life is in the minutes range
-> They are inactivated and degraded by peptidases
59
From which precursor molecule are steroids produced as derivatives?
Cholesterol
60
From which molecule are terpenes produced as derivatives?
Mevalonate
61
Name the main function of terpenes in insects.
Regulation of development and behavior
62
What are the steroid-producing tissues in human?
1. Adrenals
2. Gonads (ovaries, testes)
3. Brain
4. Gut
63
By which enzyme is the steroids biosynthesis catalyzed?
Cytochrome P450 oxidoreductases
64
What is the medical function of aromatase?
Convertion of testosterone to estrone
65
How long is the half-life of steroid hormones and how are they degraded?
-> Their half-life is in the hours range
-> They are degraded by redox conversion, esterfication and
excretion
66
Name four aspects which are regulated by amino acid derivate hormones.
1. Stress response
2. Energy metabolism
3. Circadian rhythm
4. Lactation
67
What are the two precursors of amino acid derivate hormones?
Tyrosine
Tryptophan
68
What are the two reaction mechanisms needed for the AA-derived hormone biosynthesis?
1. Hydroxylation
-> rate-limiting step
2. Decarboxylation
-> activating step
69
Under which conditions is melatonin secreted and suppressed?
-> Secretion in the absence of light (night)
-> Suppression by blue light
70
What are the AA-derived hormone-producing tissues in human?
1. Adrenals
2. Brain
3. Pineal (Zirbeldrüse)
71
How long is the half-life of AA-derived hormones and how are they inactivated?
-> Their half-life is in the minutes range
-> They are inactivated by COMTs or by deamination by
monoamine oxidases (MAOs)
72
What are Catocholamines?
AA-derived hormones (derived from tyrosin)
73
What are the three main catecholamines?
1. Dopamine
2. Noradrenaline
3. Adrenaline
74
Name five hypothalamic trophic hormones.
1. TRH: Thyrotropin-releasing hormone
2.CRH: Corticotropin-releasing hormone
3. GHRH: Growth homone-releasing hormone
4. GHIH: Growth hormone-inhibiting hormone
5. GnRH: Gonadotropin-releasing hormone
75
Name the six pituitary trophic hormones and their site of action.
1. Prolactin - Lactocytes
2. TSH - Thyrocytes
3. ACTH - Adrenocortical cells
4. GH - Hepatocytes
5. LH - Theca and granulosa cells
6. FSH - Germ, Sertoli and granulosa cells
