Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Endocrinology Final > Principles of Endocrinology > Flashcards

Principles of Endocrinology Flashcards

1
Q

Hormone

A

Chemical secreted in trace amounts by one or more cells (and carried in the bloodstream to another cell) where it modulates a specific biochemical or physiological response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the difference between endocrine and exocrine?

A
  1. Endocrine: through blood
  2. Exocrine: through duct
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Gland

A

Organ which can secrete a particular chemical substance for use within the body or into the surroundings (single gland may secrete multiple hormones but not all glands secrete hormones) (ex: salivary gland)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Endocrine signaling

A

Uses circulating system to transport ligand to target cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Paracrine Signaling

A

Ligand acts on nearby cells (ex: synapse (neurocrine))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Autocrine Signaling

A

Ligand acts on secreting cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Tropic Hormone

A

Hormone that targets another endocrine tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Protein and Peptide Hormones

A
  • Few amino acids or hundreds
  • Linear, ring structure or dimers
  • Transcription and translation
  • One gene can produce different proteins (alternative splicing)
  • Post-translational regulation can also lead to several products
  • Ex: Proopiomelanocortin (POMC): mutation impacts metabolism and stress
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Peptide Hormone Production

A
  1. Transcription (Nucleus)
  2. Translation (ER: ribosomes)
  3. Processing (ER -> vesicles -> Golgi)
  4. Packaging (Golgi -> secretory vesicles -> secretion)
  • Preprohormone (ER) -> Prohormone (vesicle) -> hormone -> degraded or reuptake
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Regulated Secretion

A
  • Peptide hormones
  • cell stores hormone in secretory granules and releases them in bursts when stimulated
  • Most common
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Constitutive Secretion

A
  • Peptide hormones
  • Cell does not store hormone, but secretes it from secretory vesicles as it is synthesized
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Neurotransmitters

A
  • Enzymatically modified amino acids
  • Synthesized by neurons and released into the synaptic cleft
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Neurochemically Active Amino Acids

A
  • Fast excitatory/inhibitory transmission
  • Glutamate (+): exhibitory
  • GABA (-): inhibitory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Monoamines

A
  • One amino acid connected to aromatic ring
  • Modulation of network activity (slower)
  • ex: Catecholamines: Dopamine (DA), Norepinephrine (NE, NA), Epinephrine, Serotonin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Peptides (Neuromodulator Peptides)

A
  • Slower modulation of circuit function
  • ex: Cannabinoid, oxytocin, orexin, CART
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Acetylcholine

A

Synthesized via enzymatic modification of precursors acetyl-CoA and choline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Steroid Hormone Synthesis

A
  • Synthesis stimulated by tropic peptide hormones
  • Mainly produced in adrenal cortex and gonads
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Cholesterol

A

Precursor for all steroid hormones and vitamin D3 and steroid hormone metabolites and bile acids

19
Q

Explain the two types of corticosteroids produced in the adrenal cortex.

A
  1. Glucocorticoids: glucose + cortex + steroid; role in glucose metabolism, immune/stress response
    - Cortisol, corticosterone, cortisone
  2. Mineralocorticoids: regulates electrolytes and fluid balance (aldosterone)
20
Q

What type of corticosteroids are produced in the zona glomerulosa of the adrenal cortex?

A

Mineralocorticoids

21
Q

What type of corticosteroids are produced in the zona fasiculata of the adrenal cortex?

A

Glucocorticoids

22
Q

What type of corticosteroids are produced in the zona reticularis of the adrenal cortex?

A

Sex steroids

23
Q

What is produced in the adrenal medulla?

A

Catecholamines

24
Q

What is the rate limiting step in steroid hormone synthesis?

A
  • Cholesterol -> Pregnenolone
  • Side chain cleavage
25
Q

Adrenal Medulla

A
  • Derives from ectoderm (neural crest)
  • Contain chromaffin cells
  • Sympathetic innervation
26
Q

Adrenal Cortex

A
  • Develops from mesoderm
  • Divided into three zones (zona glomerulosa, zona fasiculata, and zona reticularis)
27
Q

Modified Fatty Acids

A
  • Eicosanoids are derived from 20 carbons PUFA (arachidonic acid)
  • Include the prostaglandins (PG), thromboxanes (TX), leukotrienes (LT), and lipoxins (LX)
  • Autocrine and paracrine action
  • Most prostaglandins have five membered rings with substituent determining the subclass (letter)
  • Number following the third letter designates the number of double bonds in the two-side chain
28
Q

Modified Fatty Acid Hormone Synthesis

A
  1. Arachidonic acid is released from the membrane by phospholipase A2 (Rate-limiting step)
  2. COX produces the cyclic endoperoxide intermediates (PGG2 and PGH2)
  3. Eicosanoids
  • Anti-inflammatory steroids inhibit phospholipase A2
  • COX inhibitor (aspirin)
29
Q

Explain the difference between humoral hormonal, and neural.

A
  1. Humoral: response to changes in composition of extracellular fluids (levels of ion/nutrients in the blood)
  2. Hormonal: stimulated by other hormones (presence or absence)
  3. Neural: stimulated by nerves
30
Q

Principle of homeostasis

A
  • Hormone is released based on the requirement for a biological response
  • Once response is met, secretion is inhibited to prevent over response
  • Most endocrine systems have feedback loops to limit or regulate hormone synthesis and/or release
  • Feedback can be direct or indirect via the CNS
31
Q

Receptor Signaling

A
  • Presence of specific protein receptor in cell is the target for hormone
  • Receptors are subject to removal/inactivation
32
Q

Protein based hormone signaling

A
  • Prostaglandins included
  • Short half-life
  • Cell surface receptors
33
Q

Steroid based hormone signaling

A
  • Thyroid hormone included
  • Long half-life
  • Intracellular nuclear proteins
34
Q

Explain the two domains of receptors.

A
  1. Ligand-binding domain (stereospecific)
  2. Effector domain that responds to the presence of the hormone and initiates biological response
35
Q

Cell Surface Receptors

A
  • Three domains:
    1. Extracellular component
    2. Membrane-spanning component (20-25 AA organized into an alpha-helix to cross the membrane)
    3. Intracellular component
  • Can be a single polypeptide (N-terminus outside the cell, C-terminus inside)
  • Can be composed of subunits (ion channels)
  • Classified based on number of membrane spanning regions and cytoplasmic part response to ligand binding
  • Ex: GPCRs
36
Q

G-Protein Coupled Receptors (GPCRs)

A
  • Most common, ligand and response specific
  • Act via G protein complex to activate enzymes
  • 7 transmembrane domains (single polypeptide chain)
  • Engage second messengers (ex: IP3, DAG, Ca2+, cAMP) for signal amplification
  • Ex: GnRH-R, muscarinic AChR
  • Inactive G-proteins: three subunits in a heterotrimer (alpha, beta, gamma)
  • Subunits (alpha and gamma) have lipid moieties binding them to the membrane
  • GDP (guanosine diphosphate) is bound to the alpha subunit
  • Ligand binds to the receptor -> GDP is replaced with GTP
  • Receptor acts as the guanine nucleotide exchange factor (GEF)
  • alpha-subunit dissociates and moves through the membrane to a nearby protein (enzyme, ion channel)
37
Q

Tyrosine Kinase Receptors

A
  • Single membrane spanning receptors
  • Dimerize upon ligand binding
  • Exception: IR and IGF-1R dimers of hemireceptors
  • Kinase activity: main cytoplasmic constituent and initiator of signal transduction
  • Main signaling pathway engaged by receptor tyrosine kinases (ex: MAP kinase cascade, protein kinase C pathway, JAK/STAT pathway)
  • Each phosphorylation steps: amplification of the response (small concentration of hormone)
38
Q

Ligand Gated Ion Channels

A
  • Ion specific channels open when ligand binds to the receptor
  • Rapid movement of ion along concentration gradient (first message)
  • Ex: nicotinic AChR, 5-HT3R (serotonin)
  • 5 Subunits, spanning the membrane 4 times to form a cylinder
39
Q

Cell Surface Receptor Signaling

A
  • Ligand binding to the exterior of the cell and initiate a signaling cascade on the interior of the cell that changes “physiology” in the target cell
  • Can change: protein transport, protein synthesis, secretion, ion channels, gene expression
40
Q

Nuclear Receptors

A
  • Found in the nucleus or cytoplasm (will move to nucleus) of target cells
  • May be bound to corepressor (chaperone) molecules which suppress DNA transcription
  • Structure include a DNA-binding domain (highly conserved domain (C) and variable domain (D)) (regulation of gene expression/transcription)
  • DNA-binding site consists of 2 zinc fingers
  • Binds DNA at the hormone response element (HRE)
  • Ligand binding domain is less conserved but adopts approximately the same three-dimensional structure in all the receptor (12 alpha-helices arranged in three layers)
  • Regulates gene transcription
  • Response can include an early and delayed response in transcription of target genes
41
Q

Explain the receptor/hormone interaction.

A
  • KD (Dissociation constant): ligand concentration at which receptor is half saturated with ligand
  • KD = R/RL
  • Receptors are cellular proteins with: high affinity, specificity, saturability
  • Receptors have agonists and antagonists
42
Q

What can affect the biological response?

A
  1. Concentration ligand [L]: rate of production, rate of degradation/elimination
  2. Number of available receptors on the cell [R]cell: sensitivity, competitive binding, saturation
43
Q

Explain diabetes in regards to a problem with the receptor versus the ligand.

A
  1. Type 1: Insulin dependent (IDDM), normal R, no pancreatic beta-cells (no L)
  2. Type 2: Non-insulin dependent (NIDDM), impaired R function, increased circulating L

Endocrinology Final (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions