Chapter 5: The Endocrine System Flashcards
Peptide Hormones
Have surface receptors and act through the second messenger system.
The peptide hormone is considered the ____; it binds to the receptor and triggers the transmission of a second signal, known as the ____.
- First Messenger
- Second Messenger
Steroid Hormones
Bind to intracellular receptors and function by binding to DNA to alter gene transcription.
How are amino acid-derivative hormones synthesized?
Are made by modifying amino acids, such as the addition of Iodine to Tyrosine (in thyroid hormone production)
Direct Hormones
Secreted into the bloodstrean and travel to a target tissue, where they have direct effects.
Second Messenger
Substance that is mobilized within a cell after the binding of a hormone to its receptor.
Hormone Amplification
When one hormone molecule may bind multiple receptors before it is degraded also each receptor may activate multiple enzymes, each of which will trigger the production of large quantities of second messengers. Thus, each step can result in an increase in signal intensity
Amino acid derivative hormones mechanism
It is very unpredictable.
Epinephrine and norepinephrine have extremely fast onset but are short-lived like peptide hormones think of an adrenaline rush.
Thyroxine and triiodothyronine on the other hand have slower onset but a longer duration like steroid hormones, they regulate metabolic rate over a long period of time
Tropic hormones
Hormones that require an intermediary to act.
Mnemonic for identifying hormones
Most peptide and amino acid derivative hormones have names the end in -in or -ine
most steroid hormones have names that end in -one, -ol, or -oid
Which two hormones are primarily involved in calcium homeostasis? Where does each one come from and what effect does each have on blood calcium concentrations?
- Calcitonin from the parafollicular (C-) cells of the thyroid decrease blood calcium
- Parathyroid hormone from the parathyroid glands increases blood calcium concentration
Which endocrine tissue synthesized cathecholamines? What are the two main catecholamines it produces?
The adrenal medulla synthesizes cathecholamines.
Epinephrine and Norepinephrine
Which two pancreatic hormones are the major drivers of glucose homeostasis? Where does each come from, and what effect does each have on blood glucose concentrations.
Glucagon from the alpha cells of the pancreas increases blood glucose concentration.
Insulin from the beta cells of the pancreas decreases blood glucoe concentration
Which three hormones are primarily involved in water homestasis? Where does each come from and what affect does each have on blood volume and osmolarity?
Antidiuretic hormone (ADH or vasopressin) from the hypothalamus (released by the posterior pituitary) increases blood volume and decreases blood osmolarity.
Aldosterone from the adrenal cortex increases blood volume with no effect on blood osmolarity.
Atrial Natriuretic Peptide from the heart decreases blood volume with no effect in blood osmolarity.
The release of hormones by the hypothalamus is regulated by ____.
Negative Feedback
____ directly connects the hypothalamus to the anterior pituitary.
Hypophyseal Portal System
The anterior pituitary may seem that it has all the power in the endocrine system, but it is controlled by the ____.
Hypothalamus
How do hormones travel from the Hypothalamus?
Hypothalamus -> Hypophyseal portal system -> anterior pituitary
Whereas most of the hormones in the anterior pituitary requires a factor from the hypothalamus to be released, ____ is the exception.
Prolactin
As long as the hypothalamus releases PIF (which is actually dopamine), no prolactin will be released. It is the absence of PIF that allows prolactin to be released.
Hypothalamic Negative Feedback Mechanism
The release of CRH from the hypothalamus will stimulate the anterior pituitary to secrete ACTH. ACTH will then cause the adrenal cortex to increase the level of cortisol. Too much cortisol in the bloodstream can be detrimental though. Therefore, Cortisol inhibits the hypothalamus and anterior pituitary from secreting CRF and ACTH.
____ stimulates uterine contractins during labor, as well as milk letdown (ejection of milk) during lactation, also involved in bonding behavior.
What is it secreted by?
What kind of hormone is this?
Oxytocin
Hypothalamus (Posterior Pituitary)
Peptide
____ increases reabsorption of water by increasing permeability in the collecting ducts of the kidneys.
What is it secreted by?
What kind of hormone is this?
ADH (Antidiuretic Hormone, also called Vasopressin)
Hypothalamus (Posterior Pituitary)
Peptide
____ stimulates milk production in the mammary glands.
What is it secreted by?
What kind of hormone is this?
Prolactin
Anterior Pitutary
Peptide
