Block 7 Exam Flashcards
Negative Feedback
Goes back to earlier steps in the cascade to turn off hormone release
Positive feedback
Promoting a step later in the cascade pathway
Ligand
Any molecule that binds to a hormone receptor
Agonist
A hormone or synthetic ligand that activates hormone receptor function and signal transduction
Antagonist
A naturally occurring or synthetic ligand that prevents hormone receptor activation and signal transduction
EC50
Concentration of a hormone that attains half-maximal response
IC50
Concentration of an inhibitor at which the biological response is reduced by half
Kd
Concentration at which 50% of the binding sites are occupied by a hormone
Dissociation constant
High Kd
Low affinity
Low Kd
High affinity
Potency
Sensitivity
Efficacy
Responsiveness
Amino Acid-derived hormones
Dopamine (DA) Epinephrine Norepinephrine Serotonin (5-HT) Thyroid hormone (T3/T4)
Steroid hormone
Aldosterone Cortisol Estradiol (E2) Progesterone Testosterone Vitamin D
Steroid hormone storage pools
none
Steroid hormone interaction w/ cell membrane
Diffusion through the membrane
Steroid hormone receptor location
cytoplasm or nucleus
Steroid hormone action
Regulation of gene transcription
Steroid hormone response time
Hours to days
Peptide and amine hormones storage pools
Secretory vesicles
Peptide and amine hormones interaction w/ cell membrane
binding to receptor on cell membrane
Peptide and amine hormones receptor location
Cell membrane
Peptide and amine hormones Action
Signal transduction cascades affecting a variety of cell processes
Peptide and amine hormones Response time
Seconds to minutes
PTH Receptor
G-alpha s
ANGII receptor
G-alpha i
Gi/Go
AVP, ANGII, TRH receptor
G-alpha i
ANP receptor
Guanylyl cyclase
Insulin, IGF-1, IGF-2, EGF, PDGF receptor
Tyrosine kinase
GH, erythropoietin, LF
Tyrosine kinase associated receptor (Jak/Stat)
Possible responses
Transcription independent (immediate) Transcription dependent (delayed)
Hormones that use GPCR
Hypothalamus-derived “releasing” peptides
Anterior pituitary-derived hormones
Posterior pituitary-derived vasopressin and oxytocin
Glucagon
PTH, Calcitonin, and Ca2+
Epinephrine from adrenal medulla
Second messenger molecules
Cyclic nucleotides
Lipids and lipid-derived breakdown products
Ca2+ ions
Glucocorticoid receptor
GR/GR
Mineralocorticoid receptor
MR/MR
Thyroid hormone receptor
TR/RXR
Retinoic acid receptor
RAR/RXR
Hormones that use binding proteins
Thyroid hormone Glucocorticoids Estrogens Androgens Vitamin D Growth Hormones IGF1 and IGF2
No binding proteins
Catecholamines PTH Calcitonin Glucagon Insulin ADH Renin
GHRH Target cell in anterior pituitary
Somatotroph
TRH Target cell in anterior pituitary
Thyrotroph
CRH Target cell in anterior pituitary
Corticotroph
GnRH Target cell in anterior pituitary
Gonadotroph and lactotroph
GHRH hormone released by anterior pituitary
GH
TRH hormone released by anterior pituitary
TSH
CRH hormone released by anterior pituitary
ACTH
GnRH hormone released by anterior pituitary
FSH
LH
PRL
Target of GH
Stimulates IGF-1 production
Target of TSH
Thyroid follicular cells, stimulated to make T3/T4
Target of ACTH
Fasiculata and reticularis cells of adrenal cortex, make corticosteroids
Target of FSH
Ovarian follicular cells, make estrogens and progestins
Sertoli cells, initiate spermatogenesis
Target of LH
Leydig cells, make testosterone
Target of PRL
Mammary glands, initiate and maintain milk production
AVP target
Collecting duct, increases water permeability
OT target
Uterus and breast
Autocrine
Cell stimulates self
Paracrine
Stimulates cell in close proximity
Juxtacrine
Stimulated cells immediately adjacent to the hormone-secreting cell
Endocine
Secretes hormone into the blood stream
Hierarchical control
Multiple control points
Brain involved
Simple feedback loop
No intervention from the brain
What are anterior pituitary hormones responsible for?
Reproduction
Growth
Energy metabolism
Stress
What are the posterior pituitary hormones responsible for?
Water balance
Uterine contraction
Zona glomerulosa
Aldosterone synthesis
Zona Fasciculata
Glucocorticoid production
Zona Reticularis
Androgen production
Glucocorticoid function
Metabolism of carbohydrates and proteins
Mineralocorticoid function
Water balance and ECF volume
What is the rate limiting enzyme of adrenal steroid biosynthesis
SCC
Side chain cleaving enzyme
Cortisol hormone type
Steroid
Cortisol hormone class
glucocorticoid
Cortisol precursor
Cholesterol
Where is cortisol secreted
Fasciculata
Reticularis (minor)
Physiological effects of cortisol
Gluconeogenesis Proteolysis Lipolysis Immunosuppression Anti-inflammatory activity CNS differentiation/mood Differentiation of tissues Diuretic
Cortisol inhibitors
RU-486
Aldosterone hormone type
Steroid
Aldosterone hormone class
Mineralocorticoid
Aldosterone precursor
Cholesterol
Where is Aldosterone secreted
Glomerulusa
Aldosterone physiological effects
NaCl reabsorption via ENaCs
K+ excretion
Aldosterone inhibitors
Spironolactone
DHEA/Androgens hormone type
Steroid
DHEA/Androgens Hormone class
Sex/Androgen
DHEA/Androgens precursor
Cholesterol
Where are DHEA/Androgens secreted
Reticularis
DHEA/Androgens physiological effects
Masculinization
Protein anabolism
Growth
11 Beta-HSD1 location
Liver
Adipocytes
Placenta
11 Beta-HSD1 forward reaction
Cortisone => Cortisol
11 Beta-HSD1 reverse reaction
Cortisol => Cortisone
11 Beta-HSD2 location
Kidney
11 Beta-HSD2 reaction
Cortisol => Cortisone ONLY!
When is cortisol secretion highest?
8 AM
CRH GPCR
G-alpha s => Ca2+ influx
ACTH GPCR
G-alpha s => Increased activity of P-450 and synthesis of several enzymes
Major stimulation of aldosterone regulation
High serum K+
ANGII
Minor stimulation of aldosterone regulation
ACTH
Cushing’s Disease
Pituitary adenoma
Too much ACTH production => Excess cortisol production => Decreased CRH production
Cushing’s syndrome
Excess cortisol
Addison’s disease
Primary adrenal insufficiency
Too little cortisol => Increased levels of ACTH and cortisol
Adrenal adenoma or carcinoma (Cushing’s syndrome)
Too much cortisol => Decreased CRH and ACTH
Ectopic CRH (Cushing’s syndrome)
Tumor producing CRH => High ACTH => High cortisol
Low endogenous CRH
Primary disease
Last gland in HPA axis
Secondary disease
Pituitary gland
Tertiary disease
Hypothalamus
Cortisol effect on blood sugar
Raises
Promotes expression of gluconeogenic enzymes
Primary Hyper aldosteronism
Conn’s syndrome
Adrenal carcinoma/hyperplasia
Lead to hypertension
Secondary hyperaldosteronism
Hypersecretion of aldosterone due to issue somewhere higher up in axis
What does hypersecretion of cortisol lead to
Hyperglycemia
Decreased inflammatory response
Muscle wasting
Increased abdominal adipose tissue
Pseudo-Cushing’s syndromes
Idiopathic
Obesity, depression, PCOS, diabetes, ALD
Hypersecretion of androgens can lead to:
Secondary male characteristics
Addison’s disease
Primary hypoaldosteronism
Insufficient adrenal cortex function
What can Addison’s disease lead to
Hypotension Weight loss Muscle weakness Fatigue Hyperpigmentation (increased POMC/ACTH)
Secondary hypoaldosteronism
Hyporeninemic hypoaldosteronism
Pseudo hypoaldosteronism
Why is norepinephrine not essential for life?
Released elsewhere
What enzyme is needed to convert Epi to NE
PNMT
A1-AR sensitivity efficacy
Epinephrine = Norepinephrine = ISO
A1-AR sensitivity potency
Epinephrine = Norepinephrine > ISO
Beta1-AR sensitivity efficacy
ISO = Epinephrine = Norepinephrine
Beta1-AR sensitivity potency
ISO > Epinephrine = Norepinephrine
Beta2-AR sensitivity efficacy
ISO = Epinephrine = Norepinephrine
Beta2-AR sensitivity potency
ISO > Epinephrine > Norepinephrine
Catecholamine function
Increased myocardial excitability
Increased force and rate of contraction in the heart (beta-1)
Vasoconstriction (alpha-1)
What intermediate is epinephrine converted to
Metanephrine
What intermediate is norepinephrine converted to
Normetanephrine
What are metanephrine and normetanephrine converted to
VMA by MAO
Pheochromocytoma
Life-threatening
Tumor of the adrenal medulla
Symptoms associated with sympathetic hypersensitivity
Tachycardia Headache Hypertension Hyperglycemia Gland enlargement
Environmental factors for obesity
Diet type (low fat vs high fat) Basal metabolism (UCP and neuropeptides) Level of hormones, cytokines, adipokines Quantity of sleep Microbiota Infectobesity
What do decreased leptin and adiponectin lead to
Increased food intake
Insulin resistance
UCP-1
Disrupts proton gradient
Regulation of Lipid Breakdown
Lipolysis is regulated by hormone sensitive lipase
Increase in cAMP activates lipase
Where is leptin produced
Adipocytes
Where is adiponectin produced
Adipocytes
Where is Ghrelin produced
Stomach
Where is CCK produced
Duodenum
What does leptin act on
Hypothalamus
Skeletal muscle
What does adiponectin act on
Systemic
What does Ghrelin act on
Hypothalamus
What does CCK act on
Stomach
Effect of leptin
Decrease food intake = feel full
Effect of adiponectin
Lowers blood glucose levels
Effect of Ghrelin
Promotes food intake
Effect of CCK
Decreases food intake
Effect of PYY
Decrease food intake
Results in weight loss
Effect of NPT neurons
Promotes food intake
Decrease in energy expenditure
Effect of POMC
Decreases food intake
Increases energy expenditure
What does PYY act on
Hypothalamus
What does NPY neurons act on
Hypothalamus
What does POMC act on
Hypothalamus
Brainstem
Where is PYY produced
Intestines
Where is NPY neurons produced
Hypothalamus
Where is POMC produced
Hypothalamus
Leptin and resistin
Induced by Feeding
Reduced by Fasting
Adiponectin
Positively correlated with insulin sensitivity
Plasma glucose fasting
60-80mg/dL
3.3-4.4 mM
Plasma glucose Fed
100-140 mg/dL
5.6-7.8 mM
What happens in the liver in a fasted state
Increase glycogenolysis
Increase Gluconeogenesis
Decrease Glycogen synthesis
What happens in the liver in a fed state
Decrease glycogenolysis
Decrease gluconeogenesis
Increase glycogen synthesis
What is released from pancreatic alpha cells
Glucagon
What is released from pancreatic beta cells
Insulin
Proinsulin
C-peptide
Amylin
What is released from pancreatic delta cells
Somatostatin
What is released from pancreatic F cells
Pancreatic polypeptide
How much insulin is taken up by the liver
50%
Positive modulators of insulin secretion
ATP Beta agonists (G-alpha-s) Glucagon (G-alpha-s) CCK (G-alpha-q) ACh (G-alpha-q)
Negative modulators of insulin secretion
Somatostatin (G-alpha-i)
Galanin (G-alpha-i)
Alpha adrenergic agonists (G-alpha-i)
Exercise
Oral Glucose Tolerance Test
Incretins, stimulated by oral glucose, enhance insulin release
Liver GLUT transporter
GLUT2
Muscle and adipose tissue GLUT transporter
GLUT4
What is the major stimulator of glucagon secretion
Amino acids
Glucagon GPCR
G-alpha-s
Somatostatin
Suppresses insulin, glucagon, and other hormones
Type I diabetes
Decrease insulin, preserved glucagon
Ketoacids produced lead to metabolic acidosis
Immune-mediated selective destruction of beta cells
Type II Diabetes
Resistant to action of insulin
Beta cells don’t respond to increase in glucose
Thyroxine (T4)
Less active More abundant (90%) Half life = 8 days
Triiodothyronine (T3)
More active Less abundant (10%) Half life = 24 hours
Thyroid gland follicle
Follicular epithelial cell + Follicular lumen (colloid)
Thyroglobulin
Glycoprotein sequestered by follicular cells
TRH GPCR
G-alpha-q
TSH GPCR
G-alpha s
TSH stimulates
Iodide trapping Iodide oxidation Iodination Conjugation Endocytosis Proteolysis Secretion
Type 1 5’/3’ deiodinases
Kidney
Liver
Thyroid
Skeletal muscle
Type 2 5’/3’ deiodinases
Pituitary
CNS
Placenta
Intracellular actions TH
Increase Na/K ATPase activity
Stimulates mitochondria and respiratory enzymes
Increase O2 consumption
Increase metabolic rate
Increase B-adrenergic receptor responsiveness
Extracellular and whole body response of TH (mainly catabolic)
Increase BMR Increase cardiac output Increase ventilation Increase food intake Increase gluconeogenesis/glycogenolysis Proteolysis > Proteogenesis Lipolysis > Lipogenesis
Hashimoto’s thyroiditis
Antibodies against follicular cells and TSH receptors
Cretinism
Hypothyroidism during infancy
Cretinism symptoms
Mental retardation Short stature Delay in motor development Coarse hair Protuberant abdomen
Dwarfism
Develop hypothyroidism before fusion of growth plates
Grave’s Disease
Autoimmune disorder
Cold nodules
Non-functioning
More likely to be malignant
Hot nodules
Functional adenomas or carcinoma
Pendrin defect
Iodide can’t enter colloid, backflows into bloodstream
Propylthiouracil
Block deiodinases to assess T3 levels/sources
GHRH GPCR
G-alpha s
GH inhibitors
GH
IGF-1 (directly: inhibits somatotrophs)
IGF-1 (indirectly: inhibits GHRH release, stimulates somatostatin)
Somatostatin
Growth hormone and prolactin
Same affinity for PRL receptor
PRL has no affinity for GH receptor
GH acute effects
Increased lipolysis
Decreased glucose uptake
Increases gluconeogenesis
High doses => Insulin resistance
GH long term effects
Stimulate chondrocytes proliferation
Promotes longitudinal bone growth
Stimulates EC matrix formation
Promotes growth in almost every cell of the body
Stimulators of GH release
Exercise Stress High protein meals Fasting Ghrelin
Ghrelin receptor
GH secretagogue receptor 1a (GHSR1a)
Inhibitors of GH release
Somatostatin
Obesity
Pregnancy
Hyperglycemia
Somatostatin receptor
SSTR
IGF-1
Mediates somatic long-term effects of GH
When is IGF-1 highest
~12 years of age