Endocrine Lecture Flashcards

1
Q

Endocrine Gland

A

Ductless gland that secretes its product (hormone) into circulation, influences activity of distant tissues

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2
Q

Hormone

A

Chemical substance synthesized and secreted by an endocrine gland into blood to all parts of the body

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3
Q

Target

A

Tissue with specific receptors that respond to hormonal stimulus

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4
Q

Paracrine

A

Hormone secreted by cell, diffuses into extracellular fluid, affects neighboring cell function

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5
Q

Autocrine

A

Hormone secreted by cell, affect its own function by binding to its cell surface receptors

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6
Q

Neuroendocrine

A

Hormone secreted by neuron, reaches the circulation, influences the function of other cells at another location in the body

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7
Q

Neurotransmitter

A

Chemical substance released by axon terminal into synapse, acts locally to control nerve cell function

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8
Q

NE and Epi

A

Secreted by adrenal medulla = hormone

Secreted by SNS = neurotransmitter

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9
Q

Anterior pituitary

A
Growth Hormone
Adrenocorticotropin hormone
Thyroid stimulating hormone
Follicle-stimulating hormone
Luteinizing hormone
Prolactin
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10
Q

Posterior pituitary

A

Vasopressin (antidiuretic hormone)

Oxytocin

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11
Q

Adrenal cortex

A

Cortisol
Aldosterone
Androgens

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12
Q

Adrenal medulla

A

NE

Epi

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13
Q

Thyroid gland

A

Thyroxine
Triodothyronine
Calcitonin

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14
Q

Pacreas

A

Insulin

Glucagon

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15
Q

Ovaries

A

Estrogen
Progesterone
Testosterone

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16
Q

Testes

A

Testosterone

Estrogen

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17
Q

Placenta

A

Chorionic gonadotropin
Estrogens
Progesterone
Somatomammotropin

18
Q

Chemical Classes of Hormones

A

Proteins & Polypeptides (3-200 aa) – (pp: >100)
Steroids (cholesterol= precursor)
Amines ( derived from tyrosine)

19
Q

Protein hormones

A

Pituitary
Pancreas
Parathyroid Hormones

  • Usually hydrophilic (hard to diffuse by themselves)
20
Q

Protein and Polypeptide Hormone synthesis

A

Stored in secretory vesicles until needed
- Synthesized in rough ER as PREPROhormone
- Cleaved to PROhormone in ER and transferred to golgi
Packaged into secretory vesicles and cleaved to active form and inactive fragments
Secreted via exocytosis

21
Q

Peptide hormones?

A

Water soluble
Easily enter circulatory system
Diffuse to target cells

22
Q

Steroid Hormone Synthesis

A
Synthesized from cholesterol
Not stored within cells
Lipid soluble
Diffuse across membrane
Enter interstitial fluid and then blood where they bind to plasma proteins (not water soluble)
23
Q

Thyroid Hormone Synthesis (amine)

A

Bind to a protein called thyroglobulin stored in follicles
Secretion: spllit from this protein
Combine with plasma protein thyroxine-binding globulin
– Thyroxine and triiodothyronine

24
Q

Adrenal Medullary Hormones (amine)

A

Taken up into preformed vesicles and stored until secreted
Released by exocytosis
Exist in bound and free forms in plasma
– Epi and NE

25
Regulation of hormone secretion
Feedback control Neural control: pathways controlling release Chronotropic (time) Control: cycles of the body (period, sleep-wake, etc)
26
Feedback Control Positive vs Negative?
Negative: Limits the hormone effect Positive: Acts to amplify the hormonal effect
27
Water soluble hormones
Peptide hormones & catecholamines - Dissolved in plasma, transported to target tissues - Diffuse to target cells
28
Steroid and Thyroid hormones
Circulate in blood bound to plasma proteins Protein bound hormones are inactive until dissociated bc its too large to get out of the capillary and cause an effect -- Act as a reservoir when bound -- Are in the blood longer
29
Clearance from Blood
Metabolic destruction by tissues Binding with tissues Excretion into bile or urine Increase half-life with increase plasma protein binding
30
Receptor Locations
Target cell membrane: Protein, peptide and catecholamine hormones Cytoplasm: Steroid hormones Nucleus: thyroid hormones
31
Target cell membrane
Protein, peptide, and catecolamine - Fast response Alter permeability, activate second messengers or activate intracellular enzymes
32
Cytoplasm
Steroid hormones - Longer response times (minutes to hours) Activate gene transcription and protein synthesis
33
Nucleus
Thyroid hormones Longest response times (hours to days) Activate gene transcriptions and protein synthesis
34
Cell surface receptors
Ion channel-linked receptors: open or close ion channels Enzyme-linked hormone receptors: activated receptors function directly as enzymes or activate closely related enzymes G Protein-linked: heterotrimeric GTP binding proteins, activates second messenger systems
35
Regulation and sensitivity?
Number of receptors in a tissue changes with time - Down regulation of receptors occurs due to increase hormone concentration - Decrease responsiveness to hormone
36
Decrease responsiveness to hormone
Inactivation of some receptors or intracellular protein signaling molecules Temporary sequestration of receptors inside the cell Destruction of receptors by lysosomes Decreased production of the receptors
37
Upregulation of receptors and intracellular signaling proteins?
Hormones induces greater than normal formation of receptors or intracellular signaling molecules Greater availability of the receptor for interaction with the hormone Target tissue becomes more sensitive to the stimulating effects of the hormone
38
Adenylyl Cyclase- cAMP Second Messenger system
Catecholamines, peptide and protein hormones - Rapid effects Gs proteins and Gi proteins ANTERIOR pituitary hormones
39
Membrane Phospholipid Second Messenger system
G protein --> PL-C --> PIP2 --> DAG + IP2 --> Active PKC --> Protein - PO4 or Protein + Ca2+ --> cell response POSTERIOR pituitary hormones
40
Calcium-Calmodulin Second Messenger system
Calcium enters via open channels bc of hormone receptor interaction or membrane potential change - Ca binds calmodulin which activated calmodulin-dependent PK to produce response via phosphorylation of different proteins
41
Transcriptional Mechanism
Thyroid and gonadal hormones bind with intracellular protein receptors Primary: alters gene transcription and protein synthesis Activated hormone receptor binds to a promoter region of DNA Activates or repress specific gene transcriptions
42
Measurement in Blood
Very minute quantities | Sensitive methods for hormone estimations: Radioimmunoassay or ELISA