Chapter 11 Endocrinology Flashcards
Two types of Adrenal glands
1) Adrenal medulla
2) Adrenal Cortex
Adrenal Medulla secretes what two hormones in the bloodstream? What stimulates the Adrenal Medulla?
Epinephrine & Norepinephrine
Adrenal Medulla is stimulated by the sympathetic nervous system.
-Pre-ganlionic fibers on sympathetic side that reaches out and innervates the adrenal medulla.
Where is the adrenal medulla located in regards to the adrenal cortex?
The adrenal medulla is located anterior to the adrenal cortex.
The Adrenal Medulla releases what kind of hormones?
Catecholamine hormones that include epinephrine and norepinephrine
The two primary catecholamine hormones that the adrenal medulla release are _____________ and ____________. These hormones mediate ____________ effects.
Epinephrine and Norepinephrine. They mediate sympathoadrenal effects.
“fight or flight response”
List the sympathoadrenal effects that epinephrine and norepinephrine mediate
- Inc cardiac output
- Inc heart rate
- Dialated blood vessels to the heart
- Inc alertness
- Inc Respiratory rate
- Inc metabolic rate
C H D A R M
What are the metabolic effects from the catecholamines released from the adrenal medulla?
Metabolic effects of epinephrine and norepinephrine.
Overall increased Metabolic rate due to the mediation of circulating epinephrine acting as a hormone.
- Increase glycogenolysis in the liver
- Increase lipolysis in the adipose tissue
Epinephrine released from the adrenal medulla mediates its effects (inc glycogenolysis and inc lipolysis) at target tissues via activation of _________ that increase ______________.
Activation of G-protein coupled Receptors (GPCRs) that increase intracellular second messengers.
Activation of Beta receptor leads to increased intracellular cyclic AMP (cAMP).
Activation of alpha receptors lead to increased intracellular cytosolic calcium.
Activation of what increases intracellular second messengers when epinephrine is mediating effects at target tissues?
GPCRs
What are the two intracellular second messengers that are increased by epinephrine activating GPCRs at target tissues?
Increases intracellular cAMP
Increased Calcium
When B receptors of GPCRs are activated, what intracellular second messenger is impacted?
Cyclic AMP (cAMP)
When Alpha receptors of GPCRs are activated, what intracellular second messenger is impacted?
cytosolic calcium
Explain the steps involved in how B-adrenergic receptors impact intracellular Cyclic-AMP
- The hormone (epinephrine) binds to the B-receptor on the target cells plasma membrane.
- The B-receptor then activates the associated G-protein (heterotrimeric G-protein) on the cytosolic side.
- Once activated the G-protein has an alpha effect which means that the alpha subunit breaks apart and interacts with the downstream effector.
- The alpha subunit interacts with the downstream effector, Adrenylate cyclase, which is an enzyme found on the plasma membrane.
- Activation of the enzyme Adrenylate cyclase promotes production of cyclic-AMP from ATP. (ATP —> Cyclic-AMP)
- THIS IS HOW THERE IS NOW AN INCREASED INTRACELLULAR LEVELS OF CYCLIC-AMP
- Increased cyclic AMP has several downstream effects such as activation of kinases (PKA = “protein kinase A”) or “Cyclic AMP dependent protein kinases”.
When Cyclic AMP binds to these kinases, there is an increased catalytic functioning of these kinases to allow for the phosphorylation of other proteins. (these influence the activity/effects mediated by epinephrine)
What is the name of the downstream effector enzyme that is activated when epinephrine binds to B-adrenergic receptors on target tissues plasma membrane?
Adenylate cyclase
This enzyme converts ATP into Cyclic AMP.
Role of Adenylate Cyclase
Adenylate cyclase is an enzyme that activates the production of cyclic AMP.
It converts ATP into cAMP.
Adenylate Cyclase is activated by the binding of the alpha subunit of the G-protein that is mediated by epinephrine.
What does Cyclic AMP bind to in the cytosol that leads to the downstream physiological effects of epinephrine.
The increased cyclic AMP levels from the activation of the enzyme adenylate cyclase allows for cyclic AMP to bind to the regulatory subunit of Protein Kinase.
These kinases are called (PKA = “protein kinase A”) or “cyclic AMP dependent kinases as they are regulated by cAMP.
Activation of these protein kinases leads to the increases Phosphorylation of proteins.
The phosphorylation of proteins leads to the activation and deactivation of specific enzymes that lead to the effects mediated by epinephrine.
What is the catalytic job of Protein Kinases?
Phosphorylation of proteins.
These proteins then influence the activity of various metabolic enzymes that lead to the effects mediated by epinephrine.
alpha-adrenergic receptors influence:
Intracellular levels of Ca2+
What series of steps follows alpha-adrenergic receptor activation from epipinephrine released from the adrenal medulla
- epinephrine from the blood supply binds to alpha-receptor (GPCR) on the target cell’s plasma membrane
- This activates the associated G-protein and for the alpha subunit to interact with the downstream effector enzyme that is also located on the plasma membrane
- The alpha G-protein subunit interacts with the enzyme Phospholipase C
What is the downstream effector of alpha receptor activation?
Phospholipase C
What does the enzyme Phospholipase produce? What is its role?
Once the alpha subunit from the G-protein interacts with Phospholipase, there is a cleavage of the polar head groups of the phospholipid bilayer and their acyl tails attached to the membrane.
The polar head group forms IP3.
The acyl chain produces DAG.
What is IP3? What enzyme forms it? What role does IP3 play in intracellular levels of Ca2+?
Soluble intracellular second messenger in alpha-receptor activation from epinephrine.
IP3 is formed from the polar head groups which are cleaved from their acyl tails via the enzyme phospholipase C.
IP3 then binds to IP3 receptors (calcium channels) on the ER membrane. This opens the calcium channel and allows Ca2+ to move down its electrochemical gradient from areas of high concentration in the lumen of the ER to low concentration in the intracellular cytosol.
THIS IS HOW ACTIVATION OF ALPHA-RECEPTOR RESULTS IN AN INCREASED INTRACELLULAR CA2+.
As intracellular calcium levels increase, what protein does it bind to? What kinase does it bind to?
Calcium binds to a protein called calmodulin.
This calmodulin protein then binds to calcium calmodulin dependent kinases.
These kinases then increase in activity to lead to the typical downstream effects within these target cells.
Where are there high stores of calcium in cells?
Endoplasmic Reticulum of all cells.
SR in muscle cells.
Where is the adrenal cortex located in terms of the adrenal medulla ?
It lies outside of the adrenal medulla
Unlike the adrenal medulla which is controlled by the sympathetic nervous system (“fight or flight”), the adrenal cortex is controlled by what?
The Hypothalamic Pituitary Axis (HPA) controls the adrenal cortex.
When activated, what does the adrenal cortex secrete into the bloodstream?
Corticosteroids (also called steroid hormones)
How is the adrenal cortex arranged?
Its arranged into three layers or zones that release a different subset of steroid hormones into the blood supply.
-Zona glomerulosa
-Zona Fasciculata
-Zona Reticularis
What subset of steroids does the Zona Glomerulosa layer of the adrenal cortex release?
The zona glumerulosa releases mineralocorticoids. This kind of steroid largely affects the electrolyte balance within the blood supply.
Mineralcorticoids are a type of ______ that the ______ _____ layer of the adrenal cortex releases.
Mineralcorticoids largely affects the ______ balance in the blood supply.
A type of steroid that the Zona Glomerulosa layer of the adrenal cortex releases.
This steroid largely affects the electrolyte balance in the blood supply.
What subset of steroids does the Zona Fasciculata layer of the adrenal cortex release?
Glucocorticoids and sex steroids
-Glucocorticoids such as cortisol are important for the regulation of blood glucose
-Note that sex hormones are also released here but their primary source is the ovaries and testes
What subset of steroids does the Zona Reticularis layer of the adrenal cortex release?
Glucocorticoids and sex steroids
-Glucocorticoids such as cortisol are important for the regulation of blood glucose
-Note that sex hormones are also released here but their primary source is the ovaries and testes
Glucocorticoids
A steroid released from the Zona fasciculata and Zona Reticularis.
Ex: this includes cortisol
Glucocorticoids are involved in the regulation of blood glucose.
The biosynthesis of the steroid hormones (corticosteroids) from the adrenal cortex (Zona glomerulosa, Zona Fasciculata, and Zona Reticularis) are based on ________________.
Cholesterol
What mineralocorticoids does the Zona Glomerulosa release?
Aldosterone
Mineralocorticoids regulate _________
Electrolytes: Na+ and K+
Aldosterone
Increases sodium and water retention
Promotes potassium excretion in the kidneys
This is the hormone that serves to increase blood volume and pressure; and balances electrolyte concentrations
What is the major steroid hormone of the Zona Fasciculata and Zona Reticularis?
Cortisol
Cortisol
One type of glucocorticoid.
Cortisol will increase blood glucose levels
Glucocorticoids regulate ________
glucose and other metabolites.
They typically mediate catabolic effects.
Glucocorticoids also play a role in immune supression and inhibition of inflammation.
How does cortisol increase blood glucose levels?
Stimulates activation of glucogenesis
Inhibits glucose utilization in tissues
Can also provide energy by releasing and Increases fatty acid levels in the blood by stimulating lipolysis and fat cells.
What corticosteroid subset plays a role in immune supression and inhibition of inflammation?
Glucocorticoids
Steroid hormones are synthesized from __________.
Cholesterol
Where are steroid hormones produced in and secreted by?
Produced in and secreted by the adrenal cortex and gonads
Structure of cholesterol
Hydrophobic Four-ring fused structure
Hydrophobic molecule (small exception of hydroxyl group on left hand side)
Is cholesterol hydrophobic or hydrophilic molecule?
Hydrophobic molecule (small exception of hydroxyl group on left hand side)
Are the steroids derived from cholesterol going to relatively hydrophobic or hydrophillic?
Hydrophobic
How do steroid hormones travel through the blood stream? Why
They travel through the bloodstream by binding to “carrier proteins”.
They need carrier proteins in order to travel through the bloodstream because steroid hormones are hydrophobic and they want to stay away from the aqueous environment.
Two features of steroid hormones
1) Hydrophobic
2) Lipophilic
What do steroid hormones recognize and bind to?
Intracellular nuclear hormone receptors
“nuclear receptors”
“intracellular receptors”
Intracellular nuclear hormone receptors are ___________ factors
Transcription
Steroid Hormones Mechanism of Action
- Steroid hormones bind to carrier protein in the blood stream so it can carry it through the blood supply.
- Enters target cell via simple diffusion
- Hormone binds to receptor protein (transcription facter) in the cytosol.
- Hormone bound to the receptor protein allows translocation into the nucleus.
- The DNA binding domain of the receptor protein sits on the DNA strand
- Upregulates mRNA
- Protein synthesis
- Steroid hormone physiological response
Via what kind of transport does steroid hormones exit blood stream and enter target cell?
Simple diffusion
What are the two domains of the receptor protein for a steroid hormone?
- Ligand-binding domain- where the hormone binds
- DNA-binding domain– recognizes and sits down on certain sequences in the DNA.
-This is the transcription factor end of the molecule
What needs to happen for the hormone-bound receptor to act as a transcription factor?
Two monomers come together to form an activated homodimer.
Explain the hypothalamic-pituitary-adrenal axis in the negative feedback control of cortisol.
Stress info –> higher brain centers –> stimulates hypothalamus to release CRH –> CRH binds to the Anterior Pituitary –> Anterior pituitary releases ACTH
What does the hypothalamus release in response to stress? (HPA: neg feedback)
CRH
What detects CRH in the HPA Axis Negative Feedback Control?
Anterior Pituitary
What does the Anterior
Pituitary release in the HPA Axis Negative feedback control that ultimately leads to release of cortisol?
ACTH
What detects ACTH in the HPA Axis Negative Feedback Control?
Adrenal Cortex
What does the Adrenal Cortex release in the HPA Axis Negative feedback control?
Cortisol
What are the three extracellular signaling mechanisms?
- Neurotransmission
- Local Signaling
-Autocrine
-Paracrine - Endocrine Signaling
Autocrine Signaling
Local signaling regulators that are produced and act within the same tissue.
-Local regulator meaning it does not travel in the blood stream
Paracrine signaling
Local signaler that is produced within one tissue type but regulates activity of a different type of tissue of the SAME organ
Endocrine signaling
- Cells produce hormone
- Endocrine gland secretes hormone into the blood stream
- Hormone travels through bloodstream
- Hormone binds to receptors on target cell
Endocrinology is the study of endocrine _______/_______, the ______ they release, and their effects on ____________.
glands/tissue
Hormones
Target tissues
Hormones are carried via _______.
The blood stream
Hormones regulate body ________, _________, and ________.
Metabolism, growth, and development.
What are the two hormone precursor molecules?
- Prohormones
- Prehormones
Prehormones (aka Preprohormones)
inactive hormone precursor molecule that is secreted from the endocrine gland (as inactive form) and travels to the target cell.
Becomes activated hormone within the target cell.
Prehormones become activated hormone __________ they reach target cell.
Once
Prohormones
-size/activity compared to hormone?
-Where are they produced?
-When are they converted to active form?
Inactive hormone precursor molecule that is much larger and less active than the hormone.
Prohormones are produced in endocrine gland.
They are converted into the shorter, active hormone PRIOR TO SECRETION.
Prehormones are released from endocrine gland in their __________ state, whereas Prohormones are released from endocrine gland in their _________ state.
Pre– inactive
Pro– active
The nervous system and endocrine system overlap in terms of __________ __________ and _________ _________.
Ex?
Chemical transmitters; Receptor Proteins
Dopamine and Epinephrine act as both NT and hormone
Most target tissues are regulated by ________ hormones; downstream effects may be ____________ or _________.
Multiple;
Complementary or Antagonistic
Target Tissue response is dependent on _______________.
Plasma concentrations of hormones
What are the two ranges of hormone concentration in the bloodstream?
Do these ranges lead to “Sensitization/Desensitization” and/or “Upregulation/Downregulation”?
- Physiological Range – aka normal range of hormone concentration. This leads to sensitization of the target cell hormone receptors– meaning only a small amount of hormone is needed for receptors to become activated. This sensitivity is due to upregulation of receptors.
- Pharmacological Range— abnormally high concentration of hormone in blood stream
-Desensitization of receptors on target cell (bc prolonged exposure dec response)
-Downregulation of receptors (less receptors on membrane)
-Smaller/Less response from target tissue
Physiological range is the ________ range for plasma concentration of hormones. The hormone receptors on target cells are _______ sensitive. This is due to _________ of receptors. Meaning there are ________ receptors located on plasma membrane. This causes a ________ hormone response from target cell.
Normal
Less Sensitive/ Sensitized
Upregulation; more receptors
Greater response
Pharmacological range is the ________ range for plasma concentration of hormones. The hormone receptors on target cells are _______ sensitive. This is due to _________ of receptors. Meaning there are ________ receptors located on plasma membrane. This causes a ________ hormone response from target cell.
Abnormally high; less sensitive (desensitized); downregulation; less receptors; smaller
What are the three chemical structures in classifying hormones?
1) Amino Acid derivatives
2) Peptides & Proteins
3) Steroids
What hormones are amino acid derivatives?
Adrenal Medulla – epinephrine and norepinephrine
Thyroid Hormones
Pineal Gland– Melatonin
What endocrine gland secretes melatonin?
Pineal Gland
What hormones are classified as Peptides and Proteins?
- Hypothalamic and Pituitary hormones
- Insulin and glucagon (pancreas)
- Parathyroid Hormone
What hormones are classified as Steroids?
Where are steroids derived from?
Steroids are derived from Cholesterol.
1. Corticosteroids– from adrenal cortex
2. Sex steroids – from gonads
What endocrine gland secretes sex hormones?
Gonads
Hydrophilic hormones interact with __________________ receptors at target tissues.
-All ______ & _______ hormones.
Examples?
Cell-surface
All peptide and protein hormones.
Examples: epinephrine and Norepinephrine
Hydrophobic (or lipophilic) interact with __________ receptors at target tissues.
Example: ______ hormones & _______ hormones
Intracellular
Steroid Hormones & Thyroid Hormones
Enzyme-linked receptors are activated via binding of substrate (insulin) to it’s enzyme in its _________ state. This causes activation of ____________ ______ _________. (ex)
Examples of hormones that bind to enzyme-linked receptors?
Bind to unactivated enzyme.
Activated intracellular 2nd messengers: cAMP, Ca2+, kinases
-Insulin, growth factors
G-protein coupled receptors act through _____________ such as ________.
Examples of hormones that bind to G-protein coupled receptors?
Act through intracellular 2nd messengers (cAMP, Ca2+, kinases)
-Epinephrine and Norepinephrine
Intracellular receptors act as __________ in the ________.
Example of hormones that bind to intracellular receptors?
transcription factors in the nucleus
Steroid & thyroid hormones.
The ___________ comprise the endocrine portion of the pancreas.
Islets of langerhans — clusters of alpha and beta cells
Alpha-cells of Pancreatic Islets of Langerhans secrete ___________. This _______ blood glucose.
Glucagon- raises blood sugar
Beta-cells of Pancreatic Islets of Langerhans secrete ___________. This _______ blood glucose.
Insulin— lowers blood sugar
Changes in _______ levels influence secretion of pancreatic hormones (glucagon & insulin)
blood glucose levels
Pancreatic hormones regulate ____________ levels and influence ________ ________.
Insulin promotes _________.
Glucagon promotes _______.
Target tissues of Pancreatic Hormones:
1.
2.
3.
Pancreatic hormones regulate blood glucose levels and influence cellular metabolism.
Insulin promotes anabolism.
Glucagon promotes catabolism.
Target tissues of pancreatic hormones:
1. Liver
2. Skeletal Muscles
3. Adipocytes
Target tissues of Pancreatic Hormones:
1.
2.
3.
- Liver
- Skeletal Muscles
- Adipocytes
When blood glucose levels rise, this stimulates ______ cells to release ________.
Beta cells; insulin
Insulin _______ blood glucose levels and promotes the ______ of energy in the form of ________ and ______.
Lowers;
Storage of energy in form of glycogen and fat.
If blood glucose levels are______ from fasting, the ______ cells are stimulate and secrete ________.
Low; Alpha Cells; Glucagon
Glucagon secretion from alpha cells stimulates the liver to hydrolyze ________ into _______. This process is called _________. As a result, the liver secretes _______ into the blood.
Glycogen (storage form of glucose in liver) —-> Glucose (raise blood glucose levels)
Glycogenolysis
Glycogenolysis
Glycogen —> Glucose
To raise blood sugar.
When blood glucose levels are low, Glucagon is secreted from alpha cells of the pancreatic islets. Glucagon travels to target tissue, the liver, to stimulate hydrolysis of glycogen into glucose. Blood glucose levels become increased.
Glycogen
The storage form of glucose in the liver.
Anabolism:
Precursor molecules —> Cell Macromolecules
Which pancreatic hormone promotes anabolic processes?
Anabolism: chemical reactions within cells that convert smaller molecules into bigger ones.
–Uses energy (ATP, NADH, NADPH, FADH2)
Precurser –> Cell Macromolecules
Amino acids –> Proteins
Sugars –> Polysaccharides
Fatty Acids –> Lipids
Nitrogenous bases –> Nucleic acids
Insulin promotes anabolism. (lowers blood sugar by converting blood glucose into storage forms such as glycogen in liver and fat) This requires energy.
______ promotes Anabolism
Insulin
_______ promotes Catabolism
Glucagon
Catabolism breaks _________________ such as _____,_____,&_____ into ___________ such as _____,_____, & _____. These processes are energy ________.
What pancreatic hormone promotes Catabolism.
Energy Containing Nutrients such as Carbohydrates, Fats, and Proteins into Energy Depleted End Products such as CO2, H2O, and NH3.
Energy generation:
ADP –> ATP
NAD –> NADH
NADP –> NADPH
FAD –> FADH
Glucagon promotes catabolism (inc blood glucose levels by breaking down glycogen, the storage form of glucose, into glucose. This process of breaking down glycogen into glucose releases energy.
When blood glucose levels are high, ____ cells in pancreatic islets secrete _______, this _____ the cellular uptake of glucose to lower blood glucose levels. The cellular uptake of glucose into glycogen occurs in ____ and ________; where as glucose into triglycerides occurs in _________.
Beta cells; secrete insulin; increased cellular uptake.
Glucose –> Glycogen in liver and skeletal muscle
Glucose –> Triglycerides in adipose tissue
The insulin receptor is an ______, the most prevalent type of enzyme-linked cell surface receptor.
RTK : Receptor tyrosine Kinases
Insulin receptors is a ______.
Kinases are enzymes that __________.
Tyrosine kinases attach _____ groups to tyrosine residues within proteins.
Activated insulin receptor phosphorylates ______.
- RTK — receptor tyrosine kinase
- Phosphorylate proteins
- Phosphate
- Itself
Insulin Receptor Activation:
1. ____ half receptors form _____ prior to insulin binding.
2. Insulin binding causes ___________ of receptor.
3. Active _________ _____ of receptor phosphorylates signaling molecule.
4. Active signaling molecule causes cascade of events that lead to _______ uptake and ________ reactions.
- Two half receptors form dimer prior to insulin binding.
- Insulin binding causes autophosphorylation of receptor.
- Active tyrosine kinases of receptor phosphorylates signaling molecule.
- Active signaling molecule causes cascade of events that lead to glucose uptake and anabolic reactions.
Insulin receptor activation at target tissues:
1. Increases uptake of blood glucose ( _______ recruitment) in _____ & _____.
- Increases ______ synthesis (glucose –> glycogen) in _____ and _______.
- Increased fat stores in _________. (glucose —> ______)
- GLUT4 moves glucose from blood into muscle and fat.
- Inc glycogen synthesis in liver and muscle.
- Glucose –> triglycerides in adipocytes (inc fat stores)
Hepatocytes (liver cells) express _______ transporters.
GLUT2
GLUT2 transporters on liver cells move glucose into liver cells when blood glucose concentration is _______?
GLUT2 transporters on liver cells move glucose out of liver cells when blood glucose concentration is _______?
high
low
Insulin-responsive GLUT4 recruitment occurs only in ______ & ______ muscle and _________ tissue.
skeletal and cardiac muscle
Adipose tissue
When conc of insulin in blood increases, >___% of blood glucose is taken up by ______ and ______ tissues.
> 95%
muscle and fat
~90 muscle
~10 fat
Major effect of insulin at the liver?
Decrease gluconeogenisis (noncarbohydrate –> glucose)
Increase glycogen synthesis (Glycogenesis)
Major effect of glucagon at liver?
Increase gluconeogensis (noncarb –> glucose)
Dec Glycogenesis (glucose -> glycogen)
Increase glycogenolysis (glycogen –> glucose)
Glycogenolysis
Gluconeogenesis
Glycogenesis
Glycogenolysis= Glycogen –> glucose
Gluconeogenesis = Noncarb –> glucose
Glycogenesis = glucose –> glycogen
Exercise lowers blood sugar so what concentrations of pancreatic hormones would you expect to see in the blood?
Higher glucagon conc in blood. (this gets secreted when blood sugar is low)
Decreased insulin conc in blood
What is the master control of the endocrine systems?
This is where there is an integration of _______ and endocrine systems.
HPA: hypothalamus Pituitary Axis
Neuro
The Pituitary gland is called ______.
Hypophysis
The pituitary gland (hypophysis) is comprised of the __________ lobe and the _______ lobe.
Anterior lobe and posterior lobe
The Anterior Pituitary lobe is called ____________.
Hormonal regulation of the anterior lobe is regulated by ________.
Adenohypophysis;
Hormonal regulation by the hypothalamus.
Posterior lobe of Pituitary gland is called ________.
Posterior lobe is a _________ extension of the ________.
Neurohypophysis
Neuro extension of the hypothalamus
Which lobe of the pituitary gland produces and secrets its own hormones?
How is this lobe regulated?
Anterior Pituitary
The hypothalamus sends regulating hormones via blood vessels to the anterior pituitary via a “hypothalamo-hypophyseal portal system”
The ________________ is the vascular link between the hypothalamus and the anterior pituitary.
Why is this important?
hypothalamo-hypophyseal portal system;
Important in regulation of the types of hormones the anterior pituitary produces and secretes. Essentially, hypothalamus sends regulatory hormones via this vascular link to signal for activity and hormone secretion of the anterior pituitary.
What are the 6 hormones of the Anterior Pituitary?
(hint: good tits???)
- Growth Hormone (GH)
- Thyroid Stimulating Hormone (TSH)
- Adrenocorticotropic Hormone (ACTH)
- Follicle-stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
- Prolactin (PRL)
Anterior Pituitary Hormones are _________ hormones.
Suffix: “-_____”
Trophic hormones; suffix “-tropin”
Target gland mediated regulation of anterior pituitary and/or hypothalamus is what kind of feedback loop?
Negative Feedback Inhibition
Higher brain centers can influence activity of _____________ nuclei, thus influencing downstream ________ systems.
Hypothalamic
Endocrine
Growth Hormone (GH) a.k.a _________. Promotes _______.
Somatotropin
Promotes tissue growth.
Thyroid-stimulating Hormone (TSH) from the Anterior Pituitary promotes production and secretion of ____ and ____ in the thyriod.
T3 and T4
Adrenocorticotropic hormone (ACTH) promotes secretion of ________ in the ________.
glucocorticoids in the adrenal cortex
Follicle-stimulating hormone (FSH) and Luteinizing Hormone (LH) are ____________ hormones.
FSH and LH promote _________ production and ____________ secretion in the glands.
Gonadotropic hormones;
Gamete production; sex steroid secretion
Prolactin (PRL) stimulates _______ production in the ______ glands.
milk production in mammary glands.
Adrenal medulla secretes ________ & _______ into the blood.
Stimulated by ____________ nervous system.
epinephrine & norepinephrine
Stimulated by sympathetic nervous system
Adrenal cortex secretes _______________ into the blood.
Arranged into ______ layers/zones.
Zona Glomerulosa —> ___________
Zona Fasciculata & Zona Reticularis –> ___________
Adrenal cortex secretes corticosteroids (steroid hormones) into the blood.
Arranged into 3 layers/zones.
Zona Glomerulosa —> mineralocorticoids
Zona Fasciculata & Zona Reticularis –> glucocorticoids & sex hormones
Catecholamine hormones reduced by the adrenal medulla: __________ & __________
These hormones mediate ___________ effects
1. ______ cardiac output
2. ______ heart rate
3. ______ blood vessels to heart
4. ______ alertness
5. ______ respiratory rate
6. ______ metabolic rate
epinephrine and norepinephrine
All increase and dilate
Metabolic effects of epinephrine and norepinephrine (catecholamines of adrenal medulla) include increase ______________ in liver and increase _________ in the adipose tissue.
Increase glycogenolysis in liver (breakdown of storage glycogen to produce free glucose) – this breakdown releases energy that can be exerted in stressful situations (fight or flight)
Increase lipolysis in adipose tissue (breakdown of storage fat into fatty acids) — this releases energy
Epinephrine released from the adrenal medulla mediates its effects at target tissues via activation of ________ that increase intracellular second messengers:
________ and ______.
GPCRs
Increase intracellular second messengers: cAMP and Calcium
Epinephrine circulating in the blood stream binds to ___-adrenergic receptor to increase intracellular second messenger cAMP.
The G-protein interacts with downstream effector enzyme _______; its located on the plasma membrane. This effector converts ATP into cAMP.
Increased intracellular cAMP levels activates ______ kinase __.
Active Protein kinase _________ ________.
Phosphorylation of proteins leads to ________/_______ of specific enzymes that lead to downstream effects mediated by epinephrine.
B-adrenergic receptor
Adenylate cyclase
Protein-Kinase-A
Phosphorylates Proteins
Activation/Inactivation
Binding of epinephrine to ___-adrenergic receptors results in increased intracellular calcium levels.
The associated G-protein interacts with downstream effector enzyme _______ located on plasma membrane of target cell.
Activation of this enzyme cleaves polar head groups and acyl chain of phospholipid bilayer to form ____.
This soluble second messenger binds to ____ receptor on the ____ membrane. This opens _____ channel to increase intracellular _____ levels
Calcium binds to a protein called _________.
____________ respond to inc in intracellular calcium levels and lead to ________ effects.
Alpha
Phospholipase C
IP3
IP3 receptor (Ca+ channel) on Endoplasmic Reticulum; opens calcium channel; inc calcium levels
Calmodulin
Kinases; Downstream effects
When both Beta-adrenergic and alpha-adrenergic receptors get activated by epinephrine at the same time, there is a ________ that promotes ________ AKA the breakdown of ________ into _______.
Why is this important?
Convergence that promotes glycogenolysis aka the breakdown of glycogen into free glucose.
This free glucose enters bloodstream and travels to other tissues to provide them with energy needed for “fight or flight”.
Mineralocorticoids regulate ____ and ____.
Example of mineralocorticoid is _________.
Na+ and K+
Aldosterone
Aldosterone is a mineralocorticoid that is released from the Zona _______ of the adrenal cortex.
Aldosterone increases ___ and ____ retention as well as ___ excretion in the kidneys.
This results in increases in ________ & _______; balances ________.
Glomerulosa
Aldosterone increases Na+ and H2O retention as well as K+ excretion in kidneys.
Increases in blood volume and pressure; & balances electrolytes
Glucocorticoids regulate ______ and other metabolites. Have _________ effects.
______ is an example of common glucocorticoid.
Glucocorticoids play a role in _________ supression and inhibition of __________.
Glucose
Catabolic
Cortisol
Immune supression and inhibition of inflammation
Cortisol is a glucocorticoid released from the zona ________ & zona ________ layers of the adrenal cortex.
Cortisol _________ blood glucose levels by stimulating _________ which breaks down ________ into _______.
Cortisol _______ glucose utilization in the tissues.
Cortisol _____ fatty acid levels in the blood by stimulating ________.
Fasciculata and Reticularis
Increases blood glucose levels by stimulating gluconeogenesis which breaks non-carbohydrates into free glucose.
Cortisol inhibits glucose utilization in the tissues.
Cortisol increases fatty acid levels in the blood by stimulating lipolysis.
Sex steroids are a type of corticosteroids released from zona _______ and zona _____ of the adrenal cortex. These include weak ______ that supplement _______ hormones.
Zona fasciculata and Zona reticularis
Weak androgens that supplement gonadal hormones.
What are the two thyroid hormones?
Hypothalamus secretes ______, Anterior Pituitary secretes ________, and the thyroid gland secretes ________.
Thyroid ______ cells transport _____ from the blood into the colloid. (the space inside each follicle composed of non-cellular material)
Iodine is attached to ________ residues on ___________. (MIT & DIT)
T3= Triiodothyronine
T4 = Thyroxine (more abundant circulating hormone)
Hypothalamus –> Thyrotropin-Releasing Hormone (TRH)
Anterior Pituitary –> Thyroid Stimulating Hormone (TSH)
Thyroid Gland –> T3 & T4
Thyroid follicular cells transport iodine from blood –> colloid.
Iodine is attached to tyrosine residues on thyroglobulin (MIT & DIT) to form T3 and T4.
Thyroid hormones are synthesized from the precursor amino acid ________.
Tyrosine
Two Main Functions of Follicular Cell:
1) Grab circulating ______ in blood and bring it to colloid.
2) Conjugate iodine into ring structure
3) Create ____ & ____.
4) T3 and T4 bind to ________.
5) Presence of _____ outside the cell leads to ________.
6) Release of T3 and T4 into ______ of follicular cells.
7) T3 and T4 undergo simple diffusion to enter bloodstream (bc they are ________)
1) Grab circulating iodine in blood and bring it to colloid.
2) Conjugate iodine into ring structure
3) Create T3 & T4.
4) T3 and T4 bind to thyroglobulin.
5) Presence of TSH outside the cell leads to endocytosis.
6) Release of T3 and T4 into cytosol of follicular cells.
7) T3 and T4 undergo simple diffusion to enter bloodstream (bc they are hydrophobic)
______ is the binding hormone for thyroid hormones
TBG
