Endocrine Test 1 Flashcards
What are the major targets of growth hormone in the body?
Adipose, liver, pancreas
What endocrine gland secretes prolactin?
Pituitary gland
Name the regulators of prolactin
- Where are these regulators secreted from?
- What is their effect ton prolactin?
Dopamine(hypothalamus) - restrains prolactin production - so the more dopamine the less prolactin
estrogen/oestrogen - increases the production and secretion of prolactin - *higher levels of this seen in women’s blood during menstruation
Where is ADH made?
Hypothalamus
The nerve cells transport ADH from the hypothalamus to where? Then where is it released?
Posterior pituitary then released into the blood stream
Important role of ADH
- helps control blood pressure by acting on the kidneys and the blood vessels
- conserve the fluid volume in the body
Higher concentrations of ADH cause blood vessels to _________ and this ________ blood pressure
cause blood vessels to constrict (get narrower) and this causes the blood pressure to increase
How is oxytocin secretion activated?
Stimulation of sensory neurons in the mammary glands and uterine cervix - triggers spinal sensory pathways which activate specific hypothalamic neurons via action potentials - released from the posterior pituitary
Oxytocin can be inhibited by what two factors?
Stress and alcohol
What are the two actions of oxytocin?
Stimulates contractions of smooth muscle with in the reproductive tracts as well as the mammary glands.
What is the effect of plasma proteins bound to hormones?
hormones are related to the tissue cells slowly
What hormones does the Anterior Pituitary secrete?
ACTH TSH FSH LH PRL GH
What hormones does the posterior pituitary secrete?
ADH and oxytocin
What hormones does the hypothalamus secrete?
thyrotropin releasing hormone, corticotropin releasing hormone, growth hormone releasing hormone, growth hormone inhibitory hormone, GnRH, PIH
What hormone does the pineal gland secrete?
Melatonin
What hormones act directly on peripheral target cells?
Prolactin, growth hormone, melanocyte stimulating hormone
What hormones act directly on other endocrine organs?
thyroid stimulating hormone, adrenocorticotrophic hormone, follicle stimulating hormone, luteinizing hormone, prolactin, growth hormone
What are the two factors that control growth hormone secretion?
Growth releasing hormone and growth hormone inhibitory hormone (somatostatin)
AKA for somatostatin
Growth hormone inhibitory hormone
What is the job of a somatomedin?
Protein that is a growth stimulating substance - Growth home cause the liver to form several small proteins that have the potent effect of increasing all aspects of bone growth
AKA for somatomedin
Insulin-like Growth Factors (IGFs)
Production of somatomedin will inhibit or stimulate GH secretion?
inhibit - because you won’t need as much of it
Somatomedian (IGF-I) are highly bound to plasma proteins
TRUE
How does growth hormone work in the body?
It does not function through a target gland but exerts its effects directly on all or almost all tissues of the body
Function of growth hormone?
promotes increased sizes of the cells and increased mitosis, and specific differentiation of certain types of cells such as bone growth cells and early muscle cells - growth of most cells and structures
Excessive GH excretion is due to what?
If it occurs in children what is it called?
If it occurs in adults what is it called?
Due to pituitary adenoma (benign tumor)
Causes giantism in children
Acromegaly in adult
Hormonal abnormalities that are controlled by GH include
- Pituitary dwarf
- Pan hypopituitary dwarf (will not pass puberty, do not develop adult sexual function, diminished mental function
- Hypothyroid (short stocky limbs, diminished mental function
- Hypo Cortisol: extremely low cortisol levels
Why is posterior pituitary not a true endocrine gland?
It is unable to synthesize hormones. It does store hormones that are produced by the hypothalamus - if there was no posterior pituitary the hypothalamus would produce a smaller amount of hormones to be released so it did not run out of it
What is the function of releasing inhibitory hormones?
Control secretion of the anterior pituitary hormones.
What are the major hypothalamic relating and inhibitory hormones?
Thyrotropin-releasing hormone (TRH) Corticotropin-releasing hormone (CRH) Growth hormone Gonadotropin-releasing hormone (GnRH) Prolactin inhibitory hormone (PIH)
Function of Thyrotropin-releasing hormone (TRH)
causes release of thyroid-stimulating hormone
Function of Corticotropin-releasing hormone (CRH)
causes release of adrenocorticotropin
Function of Growth hormone–releasing hormone (GHRH
- which causes release of growth hormone, and growth hormone inhibitory hormone (GHIH) called somatostatin, which inhibits release of growth hormone
Function of Gonadotropin-releasing hormone (GnRH)-
which causes release of the two gonadotropic hormones, luteinizing hormone and follicle-stimulating hormone
Function of Prolactin inhibitory hormone (PIH)-
which causes inhibition of prolactin secretion
What are hypothalamic hormones?
Small peptides that are rapidly destroyed
Anterior pituitary hormones are secreted into where?
General circulation
How is melatonin secretion regulated from the pineal gland?
Norepinephrine secreted by postganlionic sympathetic nerves
What does melatonin do in the body?
Suppresses metabolic rate and induces sleep
plays role in animal hibernation
regulates other hormones and maintains the body’s cicardian rhythm (24 hour clock)
suppresses the activity of the reproductive system
Steroid and thyroid hormones circulate in the blood mainly bound to…
Plasma proteins
Steroid and thyroid hormones must do what to enter a cell
They must dissociate from the plasma proteins
What is tyrosine kinase?
enzyme, that can transfer a phosphate group from ATP to a protein in a cell - it is an important mechanism in communicating signals within a cell and regulating cellular activity
What is the enzyme produces inositol triphosphate production and DAG? How does it do this?
Phospholipase C - catalyzes the breakdown of phosphatidylinositol diphosphate (PIP2) into two second messenger products (IP3 and DAG)
How is IP3 broken down?
dephosphorylated by a family of phosphatase enzymes called inositol polyphosphate phosphates
What are tropic hormones?
hormones on the anterior lobe of the pituitary that affect the growth, nutrition or function of other endocrine glands.
Hormones that have other endocrine glands as their target
What are the four tropic hormones of the anterior pituitary gland?
FLAT
four tropic hormones of the anterior pituitary gland are (F.L.A.T):
Follicle-stimulating hormone (FSH)- stimulates the growth of follicles in the ovaries and sperm development in the testes. In females, as the follicle grows and matures, the egg is readied for ovulation.
Luteinizing hormone (LH)- Work synergistically with FSH in reproduction because LH triggers ovulation in female and stimulate testosterone in production in males
Adrenocorticotropic hormone (ACTH)- Cause the adrenal glands to make a hormone called cortisol, which helps your body manage stress.
Thyroid-stimulating hormone (TSH)- It controls production of the thyroid hormones, thyroxine and triiodothyronine, by the thyroid gland by binding to receptors located on cells in the thyroid gland.
Which G protein converts GTP to GDP
G alpha
What are the three different chains of G proteins?
alpha, beta and gamma
When is G protein in active?
When GDP is bound (Alpha is bound to beta and gamma)
When is G protein active?
When the GDP is replaced with GTP (alpha alone)
What produces cAMP?
adenylyl cyclase - it converts ATP into cAMP
What is the function of cAMP
binding of the hormones with the receptor allows coupling of the receptor to a G protein, that phosphorylate specific proteins, creating a cascade effect
What breaks down cAMP?
cAMP - dependent protein kinase (phosphodiesterase)
what produces cGMP?
Gunnel cyclase - converts GTP into cyclic GMP
Function of cGMP?
Activates cGMP dependent protein kinases - that phosphorylate specific proteins, alternating their shapes and activities
What breaks down cGMP?
cGMP - dependent protein kinase
Hormones that are antagonists
block each others actions
Hormones that are agonists
mimic each other actions
synergists
multiplicative effect, each hormone acts separately but when combined the effect is greater
Additive
effect where in two or more substances or actions used in combination produce a total effect, the same as the arithemic sum of the individual effects
What ion is used as a second messenger in amino acid based hormones?
Calcium
What is the mechanisms of protein kinase?
They transfer phosphates from ATP to protein - this process is called phosphorylation
De-phosphorylation
Removes phosphorous
Phosphorylation
added a phosphorus to activate
What are second messengers?
- characteristics
- solubility
- how do they spread
nonprotein, water-soluble molecules or ions that spread throughout a cell by diffusion.
Three types of secondary messengers?
cAMP, calcium ions and associated calmodulin, products of membrane phospholipid breakdown
Hormones use cAMP to
stimulate their target tissues
cAMP is commonly coupled with what receptor?
G - protein - this is called a stimulatory g proteins
Stimulation of cAMP by the g protein catalyzes the conversion of small amount of _____ into cAMP inside the cell - this activates what?
Small amount of ATP
This activates cAMP-dependent protein kinase which phosphorylates specific proteins in the cell - triggering biochemical reactions that ultimately lead to the cell’s response to the hormone
How does CA+ enter the cell?
initiated by changes in membrane poteitonal that open ion channels or a homorone interaction with membrane reports that open calcium channels
Once entered, CA+ binds with who? and what does this do?
Ca+ binds to calmodulin - changes the cells shape - actives and inhibits protein kinases
How many calcium sites does calmodulin have?
4
Specific function of calmodulin?
Activate myosin kinase - which acts directly on the myosin of smooth mm. to cause smooth mm. contraction
Function of IP3
mobilizes Ca+ ions from mitochondria and the endoplasmic reticulum -
effects of ca+
smooth mm. contraction and changes in cell secretion
Function of DAG
activates the enzyme protein kinase C (PKC) which then phosphorylates a large number or proteins, leading to the cell’s response -
- lipid portion of DAG is arachidonic acid - this is a precursor for prostaglaninds and other local hormones that cause multiple effects in tissues through the body
Physiological functions of steroid hormones?
anti-inflammatory agents, gene regulation, rate of protein synthesis to regulating events during pregnancy
Where are steroid hormones synthesized and who secretes them?
synthesized and secreted into the blood stream via the adrenal cortex and the gonads (ovary and testies)
Explain the actions of steroid hormones?
crosses cell membrane
enters cell nucleus
hormone binds to specific receptor protein
steroid- receptor complex
complex binds to recognition sites on DNA
Transcription occurs
Two factors that can increase or decrease the concentration of a hormone in the blood?
1) rate of hormone secretion into the blood
2) rate of removal of hormone from the blood (metabolic clearance rate)
- kidney secretion
- liver into bile
- metabolic destruction
What hormones need to bind in or on the surface of the cell membrane
membrane receptors are specific mostly for protein, peptide and catecholamine hormones
What hormones need to bind in the cell cytoplasm?
primary receptors for different steroid hormones
What hormones need to bind to receptors in the cell’s nucleus?
receptors for the thyroid hormones
Hormones are what type of messengers? they coordinate what processes?
chemical messengers
coordinate complex processes like growth, metabolism and fertility
Neural intercellular commincation
point-to-point through nerves - electrical and fast in nature
neuronal cells rebase their products directly into the synaptic space; they act on another cell type
Endocrine
hormones are chemical messengers of endocrine communication they are transported through blood stream and cells which have a receptor - Cell - Blood - Target Cell
Neuroendocrine
interaction between nervous and endocrine system
two major mechanisms:
neurosecretion: neurons that secrete hormones into the circulation
direct autonomic innervation of endocrine tissues - couples CNS signals to hormone release
Neuron - blood - target cell
Paracrine
Binds and affects neighboring cells
Directly related into the intercellular space and may involve many nearby cells that have receptors for the agent - ECF
Autocrine
is an activity of a hormone or growth factors (GFs) that binds to and affects the same cell that secrets it. These substances directly stimulate (or inhibit) the cell via their surface receptors. Autocrine secretion is an important phenomenon in the regulation of the behavior of many normal cells such as macrophages, lymphocytes, fibroblasts and vascular smooth muscle cells.
