Module 1: Endocrine Physiology Flashcards
What are the 6 functions of the endocrine system?
- Maintain constant internal environment via regulation of metabolism and water/electrolyte balance
- Adaptive Stress response
- Growth and development
- Reproduction
- Red blood cell production
- Integrating with the ANS in regulating both the circulation and digestive function
In general, what are hormones?
Hormones are chemical substances that are secreted directly into the blood at low quantities.
What do hormones do? What do they inflict on?
They exert a physiological effect at a distant target tissue
What are the two major categories of hormones?
Hydrophilic and lipophilic
Describe the properties of hydrophilic hormones
- Highly water soluble
- Low lipid solubility
- Found unbound to carrier molecules within the plasma
What are the two major kinds of hydrophilic hormones?
Peptide hormones
Amines
Describe peptide hormones
They are made of peptides or proteins
Describe amines
Hormones based on a single amino acid residue
What are the two types of amine hormone?
Catecholamines
Thyroid hormones
Describe catecholamines. Give an example
Can be both free or bound to carrier molecules
Ex., nonepinephrine and epinephrine
T/F
Thyroid hormones are hydrophilic
False! Even though they are an amine hormone, they are not hydrophilic
What is the precursor to peptide hormones
Preprohormones
What are the 4 stages of peptide hormone synthesis?
- Synthesis
- Packaging
- Storage
- Secretion
Describe the synthesis stage of peptide hormone synthesis
Precursor proteins called preprohormones are synthesized by ER ribosomes
Describe the packaging stage of peptide hormone synthesis
The preprohormones are processed into active hormones and packaged into secretory vesicles
Describe the storage of peptide hormones
The vesicles they are contained in are stoped in the cell until the signal for release occurs
Describe the secretion stage of peptide hormones
The appropriate signal initiates exocytosis of the vesicles and the hormones are released into the blood
Describe lipophilic hormones
They are highly soluble in lipids and poorly soluble in water
They require carrier molecules to be transported
What general hormones are lipophilic hormones?
Amine thyroid and steroid hormones
What are all steroid hormones synthesized by?
Cholesterol
What determines the specific steroid hormone that is produced?
Depends on the specific enzymes within that cell of that tissue
How are steroid hormones stored
AHAH Trick question
They aren’t. They are released as they are synthesized
How do bound hormones interact with their target cells?
They are constantly binding and rebinding. The unbound state is when they are active and able to act on target cells
How can one determine if a hormone will act on a specific cell
It depends if the cell expressed a specific receptor for that hormone
What kind of hormone binds to specific receptors on the outside of their target cells
Peptide hormones
What kind of hormone binds to specific receptors inside their target cell. Why?
Lipophilic hormones
Because they can slip through the cell’s plasma membrane
How do peptide hormones produce an effect on a cell once it binds to the receptor?
It activates second messenger systems
Describe Cyclic AMP as a secondary messenger
- Extracellular messenger binds to a receptor, activating a G-protein. This shuttles and activates adenyl cyclase molecules
- The adenyl cyclase molecules convert ATP to cAMP, which activates protein kinase A
Protein kinase A enzymes then phosphorylate and activate target proteins, which bring about the desired response
Put the steps of cAMP messaging in the correct order:
G-protein activated
Protein kinase A phosphorylates target proteins
Proteins bring about response
adenyl cyclase converts ATP to cAMP
cAMP activates protein kinase A
adenyl cyclase molecules are activated
Extracellular messenger binds
Extracellular messenger binds
G-protein activated
Adenyl cyclase activated
Adenyl cyclase converts ATP to cAMP
cAMP activates protein kinase A
Protein kinase A phosphorylates target proteins
Proteins bring about response
In the secondary messenger system involving calcium: What initiates the reaction?
An extracellular messenger binding to a receptor
In the secondary messenger system involving calcium: an extracellular messenger binding to the receptor activates what?
A G-protein
What is the involvement of the activation of a G protein in the In the secondary messenger system involving calcium
Activates several phospholipase C enzymes
In the secondary messenger system involving calcium: what do the phospholipase C enzymes do?
Convert PIP2 into IP3 and DAG
In the secondary messenger system involving calcium: what is the purpose of IP3?
It mobilizes intracellular calcium ions, which activate calmodulin
In the secondary messenger system involving calcium: the calcium-calmodulin complex activate what? What does this do?
It activates calcium-calmodulin-dependent protein kinase, which phosphorylates and activates target proteins
In the secondary messenger system involving calcium: what do the target proteins do?
Bring about the desired response
How do steroid and thyroid hormones bring about a response within the cell?
They produce effects by regulating gene transcription and protein synthesis
Put these steps of lipophilic hormones and protein synthesis in order:
- Free lipophilic hormone diffuse across the plasma membrane and/or the nuclear membrane to interact with intracellular receptors
- DNA binding activates specific genes and produces mRNA
- The hormone receptor complex binds to the hormone response element within the DNA
- The mRNA binds to a ribosome and proteins are synthesized
- The mRNA leaves the nucleus
- The synthesized proteins lead to the cellular response of the hormone
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T/F
Neurotransmitters belong to the nervous system, and hormones belong to the endocrine system
True!
T/F
Hormones are transported across a synaptic cleft
False!
Neurotransmitters are transported across a synaptic cleft; hormones are transported by the blood
___ are produced by endocrine glands, ___ are produced by neurons
hormones; neurotransmitters
T/F
Hormones must only travel a short distance, while neurotransmitters can travel a long distance
False!
Hormones can travel a long distance, whereas neurotransmitters can only travel short
T/F
endocrine responses are fast
False!
They are quite slow
Mins to hours
T/F
Nervous control is rapid in response
True
T/F
Nervous control is long, effects can last after stimuli stops
False
That is endocrine control.
Nervous control is brief and ends when stimulus stops
T/F
Nervous control is hardwired to one specific target
True!
T/F
Endocrine control can apply to many different targets
True
Describe the structural elements and location of the pituitary gland
- Small gland
- Divided into two lobes; posterior and anterior
- Located in a bony cavity at base of skull
T/F
The two pituitary lobes have no communication with each other
True
What is the posterior pituitary gland comprised of? What is its other name
Comprised of neural-like tissues called the neurohypophysis
What is the anterior pituitary gland comprised of? What is its other name?
Comprised of glandular epithelial tissues, also called the adenohypophysis
What is a common function of the two anterior pituitary lobes?
Both release hormones that regulate the functions of other endocrine glands or organs
How is the posterior pituitary lobe connected to the hypothalamus?
Through neural pathways
How is the anterior pituitary lobe connected to the hypothalamus?
By a vascular link called the hypothalamic-hypophyseal portal system
Hormones of the posterior pituitary gland and produced where?
In the neuron cell bodies in the hypothalamus
How do posterior pituitary gland hormones get to the posterior pituitary?
They are packaged in vesicles and transported down the axons to the nerve endings in the posterior pituitary
What are the two hormones released from the posterior pituitary?
Vasopressin
Oxytocin
What is the other name for vasopressin?
Antidiuretic hormone (ADH)
What are the functions of vasopressin
Enhances the retention of water by the kidneys
Causes contraction of arteriolar smooth muscle
What are the functions of oxytocin?
Stimulating contraction of uterine smooth muscle cells during childbirth
Promoting milk ejection during breastfeeding
T/F
All hormones synthesized by the posterior pituitary are peptide hormones
False!
All hormones synthesized by the anterior pituitary are peptide hormones
Describe tropic hormones
Hormones that once released, stimulate other endocrine glands to release their hormones
T/F
The anterior pituitary gland both synthesizes and releases peptide hormones
True
What are the 6 hormones of the anterior pituitary?
Growth Hormone
Adrenocorticotropic Hormone
Luteinizing Hormone
Thyroid-Stimulating Hormone
Follicle Stimulating Hormone
Prolactin
What is the growth hormone also known as (abbreviation/other name)
GH
Somatotropin
What are the functions of growth hormone?
Responsible for regulating overall body growth
Involved in metabolism
What is adrenocorticotropic hormone also known as (abbreviation/other name)
ACTH
Adrenocorticotropin
What are the function(s) of ACTH?
Stimulates secretion of cortisol by the adrenal cortex
LH stands for what hormone?
Luteinizing hormone
What does LH do in females?
Stimulates the secretion of estrogen and progesterone from the ovaries
Is responsible for ovulation and formation of the corpus luteum
What does LH do in males?
Stimulates the release of testosterone from the interstitial cells of Leydig
What is thyroid-stimulating hormone also known as? (abbreviation/other name)
TSH
Thyrotopin
What are the function(s) of TSH?
Stimulates the release of thyroid hormones from the thyroid gland
What is the abbreviation of Follicle-stimulating hormone?
FSH
What is the function of FSH in females?
Stimulates the grown and development of ovarian follicles and promotes secretion of estrogen by the ovaries
What is the function of FSH in males?
Is required for sperm production
What is the abbreviation for prolactin?
PRL
What is a unique characteristic of Prolactin compared to the other 5 hormones of the anterior pituitary
It is the only anterior pituitary hormone that is not tropic
What is the function of prolactin in females?
Enhances breast development and milk production
What are the 7 Hypothalamic Hormones?
Thyrotropin-Releasing Hormone
Gonadtropic-Releasing Hormone
Growth Hormone Inhibiting hormone
Corticotropin - releasing hormone
Growth hormone releasing hormone
Prolactin releasing hormone
Prolactin inhibiting hormone
What is the abbreviation and function of Thyrotropin releasing hormone?
TRH
Stimulates the release of TSH and prolactin
What is the abbreviation and function of Gonadotropin releasing hormone?
GnRH
Stimulates the release of FSH and LH
What is the abbreviation and function of Growth hormone inhibiting hormone?
GHIH
Inhibits the release of growth hormone and TSH
What is the abbreviation and function of corticotropin releasing hormone
CRH
Stimulates the release of ACTH
What is the abbreviation and function of growth hormone releasing hormone?
GHRH
Stimulates the release of growth hormone