Chapter 1 - Endocrine Flashcards
What is an endocrine gland?
A gland that is will pro-fused w/ blood where chemicals are secreted directly into the blood stream.
What is an exocrine gland?
Glands that produce a secretory product from the epithelial tissue.
Define hormone
Any chemical messenger released directly into the blood that travels through the blood to bind to distant target cells
What are the three capabilities that are unique to the nervous and endocrine systems?
- Detecting change
- Processing change
- Responding to change
Name the 10 organs of the traditional endocrine system
- Hypothalamus
- Pituitary Gland
- Pineal Gland
- Thyroid Gland
- Parathyroid Gland
- Thymus
- Adrenal Gland(s)
- Pancreas
- Ovaries
- Testes
Define Humoral Stimulus
Release caused by altered levels of certain ions or nutrients
Define Neural Stimulus
Released cause by neural input
Define Hormonal Stimulus
Release caused by another hormone (tropic hormone)
Define Tropic Hormone
A hormone that causes the release of another hormone
What is the main difference between a water soluble hormone and lipid soluble hormone?
Water soluble hormones do not have a transport protein.
What does Adenylate Cyclase do?
Converts ATP into cAMP
What does cAMP activate?
Protein Kinase(s)
What does activated protein kinase do?
Phosphorylate cellular proteins
What kind of receptors do water soluble hormones bind to?
G-protein coupled receptor
What kind of response time do water soluble hormones have?
Exert response within seconds - minutes
Walk through steps of a water soluble protein.
- Binding of hormone to G-protein receptor activated G-protein. G protein activates adenylate cyclase.
- Activated adenylate cyclase coverts ATP to cAMP.
- CAMP serves as a second messenger to activate protein kinase.
- Protein Kinase phosphorylate cell proteins
- Millions of phosphorylated proteins cause reactions that produce physiological responses
- Phosphodiesterase inactivated cAMP
What is amplification?
Multiplying/amplifying the amount of something via other proteins/substances.
Why is protein kinase so important?
Protein kinase is important because they TURN ON the proteins that ultimately exert the response by pinning a phosphate group to the functional protein.
What is meant by agonist?
Stimulatory drugs (activates)
What is meant by antagonist?
Inhibitory Drugs
What would happen if you developed a diabetes medication that interfered with action of glycogen phosphorylase? What turns this protein on?
Glycogenesis
Water soluble hormones use proteins that _______ _______.
Already exist
What are examples of a lipid soluble hormone?
Steroid or thyroid hormone
Describe the pathway of a lipid soluble hormone
- Lipid soluble hormone diffuses into cell (via transport protein)
- Activated receptor hormone complex alters gene expression
- Newly formed MRNA directs synthesis of specific proteins to ribosomes
- New proteins alter cell activity
Do lipid soluble hormones work slow or fast?
Slow (hours/days/years) because they are making proteins from scratch unlike water soluble hormones that use pre—made proteins.
What does HP Axis stand for?
Hypothalamic Pituitary Axis
List the 3 endocrine pathologies
Hypersecretion - too much hormone
Hyposecretion - not enough hormone
Insensitivity - producing hormone fine but receptors that bind to it are not responsive
Describe how action potentials affect hormone release in the posterior pituitary gland.
Action potentials travel down axons of the hypothalamic neurons, causing hormone release from their axon terminals in the posterior pituitary.
What is synthesized in the paraventricular nucleus?
Antidiuretic Hormone (ADH)
What is synthesized in the supraoptic nucleus?
Oxytocin
What are oxytocin and ADH transported down to reach the posterior pituitary?
Hypothalamic Hypophyseal Tract
Once down the hypothalamic Hypophyseal tract, where are oxytocin and ADH stored?
Axon terminals of the posterior pituitary.
How are oxytocin and ADH released?
When associated hypothalamic neurons fire, action potentials arriving at the axon terminals cause oxytocin or ADH to be released into the blood.
What kind of regulation is the posterior pituitary under?
Neural regulation
Where are oxytocin and ADH released into?
The blood
What is the stimulus for release of hormones from the posterior pituitary?
Action potentials traveling down the axons of the hypothalamic neurons
How is the anterior pituitary gland regulated?
Hormonally
How does the hypothalamus regulate the anterior pituitary gland?
Hypothalamus receives signals from sensors in body that cause the reuse of hormones that stimulate the pituitary glands to secrete hormones to act on other endocrine glands.
What is a tropic hormone?
A tropic hormone is any hormone that causes the release of another hormone.
What will be in the name of all hypothalamic hormones?
“Releasing”
When you’re dehydrated, what happens to the Na+ (sodium) in your blood?
Na+ in blood INCREASES
What are the two primary roles of the hypothalamus?
- Regulates activity of the autonomic nervous system (sympathetic and parasympathetic)
- Regulates activity of the pituitary gland
Why is the hypothalamus capable of regulating these functions?
It can come into contact w/ blood.
When a person becomes dehydrated, the concentration of their blood will -
Increase
When a person becomes dehydrated, stretch gated Na+ channels in the dendrites -
Open. (They absorb water)
When neurons originating in the paraventricular nucleus are firing action potentials, ADH (anti-diuretic hormone) secretion will -
Increase.
What will happen to the cells in the collecting duct of the kidney in the presence of ADH?
They will being to re-absorb more water.
Describe the pathway for the release of ADH (anti-diuretic hormone) -
What kind of feedback pathway is this?
Stimulus - increase in concentration of salt
Receptor - Osmo-receptor
Control center - Hypothalamus
Effector - ADH (Anti-diuretic hormone)
Target - Nephron
Response - Increased blood volume (hydration)
Negative feedback loop
Explain the pathway for the release of oxytocin during childbirth starting w/ stimulus -
What kind of feedback loop?
Stimulus - breast feeding/childbirth Receptor - hypothalamus/stretch receptor Control Center - Hypothalamus Effector - Oxytocin Target - Smooth muscle in uterus Response - Bonding/Cervical Dilation
Positive feedback loop
What are some other functions of oxytocin?
Mood regulation and pair bonding
If you had a RAGE agonist, what would it do to oxytocin levels in the brain?
The levels of oxytocin would decrease as RAGE allows the crossing of oxytocin.
What kind of hormone is HGH (Human growth hormone) and where does it come from?
- Releasing hormone
2. Hypothalamic Hormone
What is the hormone produced by the hypothalamus that triggers the release of growth hormone?
Growth Hormone Releasing Hormone (GHRH)
Explain the release of growth hormone starting with stimulus -
Stimulus - drop in circulating concentration of growth hormone / when in deep sleep
Receptor - Growth Hormone Receptors
Control Center - Hypothalamus
Effect - Growth Hormone Releasing Hormone (GHRH)
Target - Liver, muscle, bone, cartilage, and other tissues.
Response - GH increases/activate growth in bone and muscle
When do you get the biggest spikes of growth hormone throughout the day?
When you’re sleeping
True or false - Prolactin is only produced and used by women
False
Explain the release of prolactin starting with the stimulus -
Stimulus - Breast Feeding Receptor - Suckling receptors Control Center - Hypothalamus (Prolactin Releasing Hormone (PRH)) Effector - Release of Prolactin Target - Mammary glands Response - Production of milk
Prolactin release is inhibited by which neurotransmitter
Dopamine, Bromocriptine, and Cabergoline
What does HPT stand for? (Think thyroid)
Hypothalamic Pituitary Thyroid Axis
What are the 2 hormones we need to know?
T3 and T4
When the hypothalamus identifies low levels of thyroid hormone, it releases -
Thyrotropin Releasing Hormone (TRH)
Low levels of circulating thyroid hormone ________ the pathway.
Activate
Describe the pathway of T3 and T4 release beginning with hypothalamus and ending with target cells
Hypothalamus - releasing TRH w/ the Hypothalamic Hypophyseal Portal System. TRH tells the Anterior Pituitary to release another hormone called thyroid stimulating hormone. (Stimulates Anterior Pituitary)
Anterior Pituitary - Releases TSH (Stimulates Thyroid Gland)
Thyroid Gland - Release thyroid hormones to target cells (stimulates target cells)
What inhibits the hypothalamus and anterior pituitary?
Thyroid Hormones
If TRH (Thyrotropin releasing hormone) isn’t being released, they ___ won’t be released.
TSH