Molecular Mechanisms of Signal Transduction Flashcards
What does Radioimmunoassay (RIA) allow detection of?
Tiny quantities of hormones in the blood stream
It is landmark technique for endocrinology
7 Major Endocrine Glands
Hypothalmus Pituitary Thyroid Kidneys Ovaries/Testes Adrenals Pancreas
What does the Anterior Piuitary secrete?
Tropic Hormones including ACTH Thyrotropin FSH LH
What does the hypothalamus secrete?
Releasing factors that target the pituitary gland
What does the posterior pituitary secrete?
Oxytocin and Vasopressin (ADH)
What else can the CNS stimulate other than the Hypothalmus?
The adrenal medulla which secretes epinephrine
What does changes in blood glucose do to the body?
It’s stimulates the pancreas which will either secrete Insulin or Glucagon
What are the 4 main types of Ligands?
Eicosanoids
Steroids
Amines
Peptides
What are some examples of protein hormones?
Hypothalmic hormones Pituitary hormones Pancreatic Hormones Leptin Renin ANF
What are oxytocin and vasopressin?
Nona peptides which differ at only 2 amino acid residues
How do oxytocin and vasopressin reach their target tissues?
Each is secreted into general circulation and transported directly
What does ADH deficiency result in?
Diabetes insipidus
What 3 protein hormones are secreted by the pancreas and what cells are the produced from?
They are produced in the islets of langerhans:
alpha cells: glucagon
beta cells: insulin
gamma cells: somatostatin
What signals hormone release in the pancreas?
[Blood Glucose]
Where are Epinephrine and Norepinephrine derived from and produced?
They are amine hormones derived from tyrosine and produced in the adrenal medulla
What are the thyroid amine hormones and how do they behave?
T3 and T4 are hormones that behave like steroids to regulate BMR
What do the gonads release?
They release androgens and estrogens which are sex steroids
What do sex steroids target and what is their action?
They target reproductive organs controlling gene expression to regulate sexual development and behavior
What kind of hormones are adrenocortical hormones?
Steroid hormones
What does the adrenal cortex release?
Corticosteroids:
Glucocorticoids - carb metabolism
Mineralocorticoids - blood electrolytes
What are the three types of Eicosanoids/Paracrine Hormones?
Prostaglandins
Leukotrienes
Thromboxanes
What happens when the ligand binds to its receptor?
It initiates a series of events that amplifies the signal
What are the two possible ultimate goals of the ligand binding to the receptor?
1) activate kinases to alter activity of existing proteins
or
2) activate transcription factors to alter gene expression
Is activating kinases a rapid or slow and transient or prolonged response?
A very rapid & transient response
Is activating transcription factors a rapid or slow and transient or prolonged response?
A slower & prolonged response
Signals are…
Specific Amplified Desensitized Integrated Transient
What does specificity mean?
A signal molecule only binds to one site that no other signals fit into
What does amplification mean?
When the enzymes activate, the number of affected molecules increases geometrically in an enzyme cascade
What does desensitization mean?
Receptor activation triggers a feedback circuit that shuts off the receptor or removes it from the cells surface
What does repeated signaling lead too?
Desensitization
What does integration mean?
Two signals of opposite effects gives a summed response from both receptors
What does transient mean?
Signals are self-limiting
Many transient systems are disrupted in disease.
What are the 6 major classes of hormone receptors?
Gated ion channels Receptor enzymes Serpentines Adhesion Steroid Orphan
What are the major classes of G proteins?
Gs: stimulates adenylate cyclase
Gi: inhibits adenylate cyclase
Gq: stimulates phosphlipase c
What does cell response depend on when it comes to G proteins?
The type of G protein coupled to the hormone receptor and available intracellular target for phosphorylation by activated protein kinase
What toxins interfere with G proteins?
Cholera Toxin
Pertussis Toxin
What are transcription factors?
Proteins that bind to specific DNA sequences within gene promoter regions and enhance or repress transcription of that gene.
What are some examples of Transcription factors
NFB Myc STAT p53 Steroid hormone receptors
What are steroid hormones carried by to reach their target tissues?
They are carrie by specific globulins in the blood
Do steroid hormones pass readily through the plasma membrane?
Yes
What do steroid hormones bind to?
Cytosolic and nuclear receptors
What are HREs?
Hormone response elements
What does the steroid/receptor complex interact with?
Specific DNA elements in genome
