DSA - Intro to Endo/Repro Flashcards
What is autocrine signaling?
When a cell secretes a chemical signal that activates a receptor on its own cell membrane
What is Paracrine signaling?
When a cell secretes a chemical signal that activates a receptor on a neighboring cell without travelling through circulatory system
What is Endocrine signaling?
When a cell secretes a chemical signal that activates a receptor on a cell that is far away, utilizing the circulatory system to reach it
What is Neuroendocrine signaling?
When a neuron secretes a chemical signal into the blood stream to activate a far away cell receptor
What are the classical endocrine organs?
Adrenal Cortex Adrenal Medulla Pancreas Thyroid Gland Parathyroid Glands Ovaries Testicles Hypothalamus Anterior Pituitary Gland Posterior Pituitary Gland Placenta
What hormones are secreted from the hypothalamus?
Thyroid Releasing Hormone (TRH) Corticotropic Releasing Hormone (CRH) Growth Hormone Releasing Hormone (GHRH) Gonadotropin Releasing Hormone (GnRH) Somatostatin Dopamine
What hormones are secreted from the Anterior Pituitary Gland?
Thyroid Stimulating Hormone (TSH) Follicle Stimulating Hormone (FSH) Luteinizing Hormone (LH) Adrenocorticotropic Hormone (ACTH) Melanocyte Stimulating Hormone (MSH) Growth Hormone (GH) Prolactin
What hormones are secreted from the Posterior Pituitary Gland?
Antidiuretic Hormone
Oxytocin
What hormones are secreted from the Thyroid Gland?
T3 - Triiodothyronine
T4 - Thyroxine
Calcitonin
What hormones are secreted from the Parathyroid Gland?
Parathyroid Hormone (PTH)
What hormones are secreted from the pancreas?
Insulin
Glucagon
What hormones are secreted from the Adrenal Medulla?
Epinephrine
Norepinephrine
What hormones are secreted from the Kidney?
Renin
1,25 - Dihydroxycholecalciferol
What hormones are secreted from the Adrenal Cortex?
Cortisol
Aldosterone
Adrenal Androgens
What hormones are secreted from the testes?
Testosterone
What hormones are secreted from the ovaries?
Estradiol
Progesterone
What hormones are secreted from the Corpus Luteum?
Estradiol
Progesterone
What hormones are secreted from the placenta?
hCG - Human Chorionic Gonadotropin
Estriol
Progesterone
hPL - Human Placental Lactogen
What type of hormone is stored in vesicles?
Peptide Hormones
What are amine hormones derived from?
Tyrosine
What are steroid hormones derived from?
Cholesterol
Describe the general synthesis pathway for peptide hormones?
DNA Transcribed into mRNA
mRNA Translated into Preprohormone
Preprohormone has signal peptide removed in ER, becoming a Prohormone
Prohormone sent to Golgi where it is packaged into a secretory vesicle, where proteolytic enzymes cleave it, forming into an active Hormone
What stimuli induce secretion of peptide hormones from vesicles?
Increase of intracellular Ca2+ via membran depolarization
OR
Activation of GPCR followed by increase in cAMP and activation of PKA
What is the Suprachiasmatic Nucleus?
SCN is a control center that regulates a circadian rhythm of secretion of Hypothalamic Releasing Hormones and Endocrine axes
What is the Pineal Gland?
Small endocrine gland in the brain that secretes melatonin and regulates Day-night cycle signals to the Suprachiasmatic Nucleus (which helps regulate hormone secretion from the hypothalamus)
How can target tissue responsiveness to a particular hormone be changed?
Increasing the number of receptors
OR
Changing the affinity of the receptors for the hormone
What is EC50?
Away of measuring hormone sensitivity
It determines the concentration of hormone required to achieve 50% of maximal tissue response
What is upregulation?
Increasing the number of receptors at a target tissue or increasing sensitivity of target tissue when hormone levels are low
Increase synthesis of new receptors
Decrease degradation of existing receptors
Activating receptors
What is downregulation?
Decreasing the number of receptors at a target tissue or decreasing the sensitivity of the target tissue when hormone levels are high
Decrease in synthesis of new receptors
Increase in degradation of existing receptors
Inactivating/desensitizing receptors
Explain the signaling cascade involved in G-alpha S recpetors
Hormone binds to GPCR
Binding causes conformational change that results in the alpha subunit being displaced from the other G protein subunits after its bound GDP molecule being replaced by a GTP molecule (as a result of the hormone binding)
Alpha subunit then activates Adeylyl Cyclase
Adenylyl Cyclase then converts ATP into cAMP
Increased intracellular cAMP causes activation of Protein Kinase A (PKA)
PKA phosphorylates downstream proteins resulting in various physiologic actions, depending on the hormone and the target tissue
Explain the signaling cascade involved in G-alpha Q receptors
Hormone binds to GPCR
Binding causes conformational change that results in the alpha subunit being displaced from the other G protein subunits after its bound GDP molecule being replaced by a GTP molecule (as a result of the hormone binding)
Alpha subunit then activates Phospholipase C
Phospholipase C then activates PIP2 into DAG (Diacylglycerol) and IP3
IP3 induces release of Ca2+ from Endoplasmic Reticulum or from the Sarcoplasmic Reticulum
DAG, with the help of increased intracellular Ca2+, induces the activation of Protein Kinase C (PKC)
What are important aspects of intracellular hormone receptors?
Intracellular receptors can either be cytosolic or nuclear
Receptor is composed of 6 domains
The hormone-receptor complex acts as a transcription factor
The E domain is the steroid hormone binding domain
The C domain is the DNA Binding domain and has 2 zinc fingers (this domain is highly conserved
How does the Guanylyl Cyclase receptor mechanism work, what hormones interact with them, how does receptor activation differ between the hormones?
Guanylyl cyclase receptors have intracellular gunaylyl cyclase domains that activate secondary messengers
Atrial Natriuretic Peptide (ANP) and Nitric Oxide (NO) are the only two hormones that interact with these kinds of receptors.
ANP binds to the extracellular domain of the receptor, causing a conformational change, and activating the guanylyl cyclase domains
NO diffuses through the membrane and activates the guanylyl cyclase domains directly
Once the Guanylyl cyclase domains are activated, they promote an increase in intracellular cGMP
cGMP activates Protein Kinase G, which acitvates downstream proteins
How do Receptor Tyrosine Kinases work, and what hormones interact with them?
Receptor Tyrosine Kinases have intrinsic tyorsine kinase somains within the receptor that are activated once hormone binds and dimerizes the receptor
When activated, the intrinsic tyrosine kinase phosphorylates itself and other proteins
Insulin and IGF both interact with these receptors
How do Tyrosine Kinase-Associated Receptors work, and what hormones interact with them?
Receptors do not have intrinsic tyrosine kinase domains, but instead non-covalently interact with with proteins that have tyrosine kinase activty (specifically JAK tyrosine kinase)
Growth Hormone interacts with these receptors
What is hypofunction?
Reduced production of a specific hormone
What is hyperfunction?
Increased production of a specific hormone
What are mass lesions?
Enlargement of an endocrine organ due to an underlying neoplasia or hyperplasia
