Endocrine - Intro Flashcards
Define
Hormones
Chemical signals (ligands) used for cell-to-cell communication by binding to receptors on/in target cells
Secretion of hormones is regulated
Classic Endocrine Glands
List the 7 main glands
- Hypothalamus
- Pituitary Gland (Anterior/Posterior)
- Thyriod Gland
- Parathyroid Gland
- Adrenal Glands
- Pancreas
- Gonads (Ovaries and Testes)
What effect does dysregulation of hormones have on the body? What causes it?
Disease can occur
caused by hypo/hypersecretion and/or nonfunctional receptors
What are some examples of diseases caused by dysregulation of hormones?
Know Some
Type I/II Diabetes
Hypo/Hypersecretion
PCOS
Addison’s Disease
Osteoporosis
Infertitility
Growth Defects
Which of the following is NOT an endocrine gland?
A. Ovary
B. Pancreas
C. Lung
D. Thyroid
E. Hypothalamus
C. Lung
How do cells communicate with each other?
General pathway of cell communication
Signal - Receptor - Response
What are the types of cellular communication?
Autocrine/Paracrine
Endocrine (Hormonal)
Neural
Neuroendocrine
What are typical responses seen in cell to cell communication?
Opening and closing of ion channels
Phosphorylation of intracellular proteins
Changing cytoskeletal structure
Making new proteins
Define
Autocrine Signaling
Signal is released by one cell and that signal binds to a receptor on the SAME cell to elicit a response
Define
Paracrine Signaling
Signal is released by one cell and that signal bnds to a receptor on a different cell in the local area to elicit a response
Define
Endocrine/Hormonal Signaling
Signal is released by one cell and the signal travels through the blood to reach its target cell
Define
Neural Signaling
Communication between nerve cells where messages between cells are sent using action potentials and neurotransmitters
Define
Neuroendocrine Signaling
A nervous cell releases a hormone into the bloodstream where it travels to reach the target cell
A cell produces and releases a molecule into the extracellular matrix. This molecule then binds to receptors on the same cell. This most accurately represents which type of cellular signaling?
Autocrine signaling
What is the pathway of thyroid hormone?
- Hypothalamus secretes TRH into bloodstream
- TRH travels to anterior pituitary gland to stimulate release of TSH into bloodstream
- TSH travels through the blood to reach the thyroid gland
- TSH stimulates synthesis and release of T3 and T4 in/from thyroid gland
What are the major classes of hormones?
Peptide/protein
Catecholamines
Steroid
Iodothyronies or thyroid hormones
Hormone behavior depends on…
Chemical composition
Form fits function
Structure of:
Peptide/protein hormones
Unique amino acid sequences
Insulin, GH, ADH
Structure of:
Catecholamines
Hormones modified from Tyrosine
Amino Acid Derived
Epi, NE, DA
Structure of:
Steroid
Hormones modified from Cholesterol
Estrogen, Testosterone, Cortisol, Vitamin D
Structure of:
Iodothyronies or thyroid hormones
Hormones derived from tyrosine and iodine
amino acid derived
T3 and T4
Epinephrine is classified as which type of hormone?
Catecholamine Hormone
Define:
Hydrophilic
Soluble in water but not oil
Water loving
Polar
Define:
Hydrophobic
Soluble in oil but not water
Water Hating
Nonpolar
Define
Lipophilic
Nonpolar
Water hating
Hydrophobic
Define
Lipophobic
Polar
Water Loving
Hydrophilic
Chemical Characteristic
A steroid hormone is…
Hydrophilic, Hydrophobic, Polar, Nonpolar, Lipophilic, Lipophobic
Hydrophobic
Non Polar
Lipophilic
Blood is an aqueous solution. How can hydrophobic (nonpolar) steroid hormones travel through the blood?
Aqueous = plasma and cells in blood
Bound to binding proteins
Binding proteins that have high affinity and low capacity for hormones…
What does it mean for the transport of hormones?
Have strong binding but cannot move many hormone molecules
Binding proteins that have low affinity but high capacity for a hormone…
What does it mean for the transport of hormones?
Can carry alot of hormone molecules but have weak binding
How do SHBG, TBG, and CBG bind steroids?
Sex-hormone binding globulin, Thyroid BG, Cortisol BG
With high specificty but low capacity
How does albumin bind steroids?
It has high affinity to bind to any steroid nonspecifically but with low affinity
What is the purpose of binding proteins?
They increase the half - life of hormones so they are not metabolized by liver and kidney
What is required before a hydrophobic hormone can be eliminated?
Metabolism by the liver and kidney
Free hormones are…
Not bound
Active
Bound hormones are…
Inactive
Can’t enter cells
Circulating hormone concentrations depend on….
What is the equation?
Binding proteins
Total [hormone] = [free hormone] + [bound hormone]
Bound hormones represent…
What is their purpose?
A back-up supply of hormones that can be used when hormone secretion is low
If binding protein concentration in the blood increases, what happens to total hormone concentration?
and [free hormone]?
[Total hormone] increases
[Free Hormone] doesn’t change
What is the relationship between [total hormone] and binding proteins?
decrease [total hormone] increase release of hormones from binding proteins
How are Peptide/Protein Hormones (Polar) produced, processed, and released?
- DNA
- Transcription of DNA to mRNA in nucleus
- mRNA moves to ER by ribosomes for translation into Preprohormone (NH2-signal hormone-copeptides)
- Unnecessary signals are cleaved in ER to become prohormones
- Prohormones move to golgi for processing and packaging into hormones
- hormones and copeptids are released in granules
Where are peptide/protein hormones stored?
In granules/vesicles until they are signaled to be released
How are catecholamines synthesized?
- Tryosine converted to DOPA by enzyme 1
- DOPA converted to Dopamine by enzyme 2
- Dopamine converted to NE by enzyme 3
- NE converted to Epi by PNMT
Start with amino acid - then use enzymes to convert to different catecholamines
Where are catecholamines made and stored?
When are they released?
Made and stored in cytosol
Released when signaled
How do polar hormones cross the hydrophobic cell membrane?
They NEED to bind to a receptor embedded in the cell membrane
Define
Ionotropic
Hormone binding directly opens ion channels
Define
Metabotropic
Hormone binding stimulates secondary messenger cascades