Hormonal Regulation Flashcards
Hormone regulation
Physiological mechanisms that regulate secretions and actions of hormones in the endocrine system
Endocrine system function
Differentiation of reproductive system and CNS in fetus
Stimulation of growth and development
Coordination of male and female reproductive systems
Maintenance of internal environment
Adaptation to emergency demands of the body
Genella characteristics of hormones
Specific rates and rhythms of secretion
Feedback systems
Only affect target cells with correct receptors
Excreted by kidneys or deactivated by liver or cellular mechanisms
When are hormones released
In response to alteration in cellular environment
Maintain a regulated level of certain substances or other hormones
Hormones are regulated by
Chemical, hormonal or neural factors
How do water soluble hormones circulate
Freely in unbound forms
Short acting
Cannot diffuse across plasma membranes
Bund to surface receptors
How do lipid soluble hormones circulate
Bound to a carrier
Water soluble hormones response time
Short acting
Water soluble hormones can or cannot diffuse across plasma membrane
Can’t
What type of receptors to Water soluble hormones bind to
Surface receptors
Lipid soluble hormones response time
Rapid and long acting
Can Lipid soluble hormones diffuse across plasma membranes
Yes
Diffuse freely
What type of receptors do Lipid soluble hormones bind to
Diffuse across plasma membranes and bind to cytosolic or nuclear receptors
Water soluble hormones
First messenger
Hormone
Signal transduction
Water soluble hormones
Second messenger
Calcium Cyclic adenosine monophosphate (cAMP) Cyclic guanosine monophosphate (cGMP) Tyrosine kinase system Inositol triphosphate
Hypothalamic-pituitary-adrenal-axis
Hypothalamus release corticotropin releasing hormone
Pituitary releases adrenocorticotropic hormone
Adrenals secrete cortisol and catecholamines
Anterior pituitary releases
Adrenocorticotropic hormone Melanocyte-stimulating hormone Somatotropic hormones Glycoprotein hormones Luteinizing hormone Beta-lipotropin Beta-endorphins
Somatotropic hormones
Growth hormone
Prolactin
Gycloprotein hormones
Follicle stimulating hormone
Luteinizing hormone
Thyroid stimulating hormone
Posterior pituitary hormones are synthesized with
Their binding proteins in the supraoptic and paraventricular nuclei of the hypothalamus
Hormones secreted by the posterior pituitary
Antidiuretic hormone
Oxytocin
Antidiuretic hormone controls
Plasma osmolality
Oxytocin controls
Uterine contractions and milk ejection in lactating women
Where is the pineal gland located
Near the centre lf the brain
What does the pineal gland secrete
Melatonin
What does melatonin do
Regulates cardiac rhythms and reproductive systems
Role in inset if puberty
Where is the thyroid gland
Two lobes on either side of the trachea with a small bridge that connect the two (isthmus)
What regulates thyroid hormones secretion
Thyrotropin releasing hormone and thyroid stimulating hormone
Thyroid hormone is secreted in response to what
TSH (thyroid stimulating hormone)
What is thyroid hormone bound to
Thyroxine binding globulin
Thyroxine binding prealbumin
Albumin
Lipoproteins
What does thyroid hormone affect
Growth/maturation of tissues
Cell metabolism
Heat production
Oxygen consumption
Where are parathyroid glands located
Behind the upper and lower poles of the thyroid gland
What does the parathyroid gland produce
Parathyroid hormone
What does parathyroid hormone do
Increases serum calcium and decreases serum phosphate
Antagonist of calcitonin = bone reabsorption and serum calcium)
What is a cofactor for parathyroid hormone
Vitamin D
Needed for function
Where are the adrenal glands located
Upper pole of each kidney
Three parts of the adrenal cortex
Zona glomerulosa (top layer) Zona fasciculata (middle layer) Zona reticularis (bottom layer)
Adrenal medulla nerves supplied by
Sympathetic nervous system
Adrenal cortex stimulated by
Adrenocorticotropic hormone
Glucocorticoid hormones effects
Carbohydrate metabolism
Anti-inflammatory and growth suppressing
Most potent natural glucocorticoid
Cortisol
Adrenal medulla cells
Chromaffin cells (pheochromocytes)
Adrenal medulla secrets
Catecholamines -> epinephrine and norepinephrine
When is cortisol secrete
During stress
What type of tissue does cortisol reach
All tissues
What does cortisol stimulate
Gluconeogenesis
What does cortisol do
Elevates blood glucose Affects protein metabolism Anti-inflammatory and immunosuppressive agent Promotes resolution and repair Induce T cell apoptosis
Abnormal levels of cortisol linked to
Obesity Sleep deprivation Lipid abnormalities Hypertension Diabetes Atherosclerosis Loss of bone density
Catecholamines released from
Adrenal medulla
Releases epinephrine
Catecholamines receptors
Alpha adrenergic: alpha 1 and alpha 2
Beta adrenergic: beta 1 and beta 2
Catecholamines increase
Proinflammatory cytokines production
Heart rate
Blood pressure
Peripheral (immune) corticotropic releasing hormone
Proinflammatory
Mast cells targeted
Induced acute inflammation and allergic reaction
Neuropeptide Y
Sympathetic neurotransmitter
Growth factor
Hormone regulation controlled by what organs (9)
Hypothalamus Anterior pituitary Posterior pituitary Thyroid Parathyroid Adrenal cortex Ovary Testes Pancreas
Consequences of impaired hormonal regulation include alteration in
Growth and development Cognition Metabolism Reproduction Adaptive responses
Mechanism of hormonal alterations Failure of: Dysfunction of: Secretory: Endocrine glands: Endocrine glands: Increased: Ectopic:
Feedback systems
Endocrine glands
Cells unable to produce, obtain, or convert hormone precursor
Synthesizes or releases excessive hormone
Fail to produce adequate amounts of hormones
Hormone degradation or inactivation
Hormone release
Target cell failure
Cell surface receptors associated disorders
Decreased number of receptors Impaired receptor function Antibodies against certain receptors Antibodies that mimic hormone action Unusual expression of receptor function
Target cell failure
Intracellular disorders
Defects in postreceptor signalling cascades
Inadequate synthesis of second messenger
Diseases of the posterior pituitary
Syndrome of inappropriate antidiuretic hormone secretion
Diabetes insipidus
Syndrome of inappropriate antidiuretic hormone secretion
Hyper secretion of ADH Clinical manifestations are: Enhanced renal water retention Hyponatremia Serum hypo-osmolality
Diabetes insipidus
Insufficiency of ADH Polyuria and polydipsia (Partial or total inability to concentrate urine) Clinical manifestations: Enhanced water excretion Hypernatremia Serum hyperosmolality
Diabetes insipidus neurogenic vs nephrogenic
Neurogenic:
Insufficient amounts of ADH
Nephrogenic:
Inadequate response to AHD
Diseases of the anterior pituitary (5)
Hyperpituitarism Hypopituitarism Panhypopituitarism Hypersecretion of growth hormone Hyoersecretion of prolactin
Hyperpituitarism
Commonly caused by benign, slow growing pituitary adenoma
Manifestations:
Headache
Fatigue
Visual changes
Hyposecretion of other anterior pituitary hormones
Hypopituitarism
Pituitary infarction: Sheehan’s syndrome Hemorrhage Shock Head trauma Infection Tumour
Panhypopituitarism
ACTH deficiency
TSH deficiency
FSH and LH deficiency
GH deficiency
Hypersecretion of growth hormone
Acromegaly:
Hypersecretion of GH during adulthood
Giantism:
Hypersecretion of GH in children/adolescents
Hypersecretion of prolactin
Caused by prolactinomas Females: Increased levels of prolactin causes amenorrhea, galactorrhea, hirsutism, osteopenia Males: Hypogonadism Erectile dysfunction
Primary hypothyroidism
Autoimmune thryoiditis (Hashimoto’s disease) Subacute thyroiditis Painless thyroiditis Postpartum thyroiditis Myxedema coma
Hyperthyroidism causes
Thyrotoxosis
Graves’ disease (pretibial myxedema)
Nodular thyroid disease = goitre
Thyrotoxic crisis (thyroid storm)
Primary hypothyroidism
Abnormality of the thyroid itself
Secondary hypothyroidism
Pituitary gland dysfunction
Does not secrete thyroid stimulating hormone
Tertiary hypothyroidism
Hypothalamus gland does not secrete thyrotropin releasing hormone-> reduces TSH and thyroid hormone levels
Congenital hypothyroidism
Hyposecretion of thyroid hormone during youth Low metabolic rate Short stature Severely delayed sexual development Possible intellectual disabilities
Myxedema
Hyposecretion of thyroid hormone during adulthood Decreased metabolic rate Loss of mental and physical stamina Weight gain Loss of hair Firm edema Yellow dullness of the skin
How do drugs for hypothyroidism work
Replace what the thyroid gland cannot produce
Work the same as endogenous (natural in the body) thyroid hormone
Euthyroid
Normal thyroid levels
Synthetic thyroid hormone T4 drugs
Levothyroxine
Synthroid, eltroxin, euthyrox
Synthetic thyroid hormone T3 drugs
Liothyronine
Cytomel
Natural thyroid hormone T3 and T4 drugs
Desiccated thyroid
Thyroid
Causes of hyperthyroidism
Graves’ disease
Mutinodular disease
Plummer’s disease (toxic nodular disease)
Thyroid storm
Hyperthyroidism affects — body systems
Results in — in metabolism
Multiple
Increased
Hyperthyroidism symptoms
Diarrhea Flushing Increased appetite Muscle weakness Sleep disorders Altered menstrual flow Fatigue Palpitations Nervousness Heat intolerance Irritability
What is a goitre
Enlargement of thyroid gland
Goitre results from
Overstimulation by elevated levels of thyroid stimulating hormone
TSH becomes elevated because there is little or no thyroid hormone in circulation
Symptoms of goitre
Cold intolerance Unintentional weight gain Depression Dry, brittle hair and nails Fatigue
Pharmacotherapy for hyperthyroidism
Radioactive iodine
Surgery
Anti thyroid drugs
Potassium iodine
Radioactive iodine
I131
Destroys the thyroid gland “ablation”
Surgery
Removes all parts of the thyroid gland
Will need lifelong thyroid hormone replacement
Antithyroid drugs
Thioamide derivatives
Ex. Thiamazole (Tapazole), propylthiouracil
Potassium iodine
Prevents the surge in thyroid hormones that occurs after surgical treatment or during radioactive iodine treatment
May cause liver and bone marrow toxicity
Alterations of the parathyroid
Hyperparathyroidism
Hypoparathyroidism
Two types of Hyperparathyroidism and manifestations
Primary and secondary Manifestations Hypercalcemia Hypophosphatemia Hypercalciuria: kidney stones Pathological fractures
Primary hyperparathathyroidism
Excess secretion of PTH from one or more parathyroid glands
Secondary hyperparathyroidism
Increase in PTH secondary to chronic hypocalcemia
Hypoparathyroidism
Abnormally low PTH levels
Hypoparathyroidism is usually caused by
Parathyroid damage in thyroid surgery
Hypoparathyroidism manifestations
Hypocalcemia
- Chvostek’s and Trousseau’s signs
Hyperphosphatemia
Thyroid carcinoma is the most common
Endocrine malignancy
Thyroid carcinoma most common cause
Ionizing radiation
How to treat thyroid carcinoma
Thyroidectomy
Suppression therapy
Radiation
Chemotherapy
Alterations of adrenal function
Cushing’s disease Cushing’s syndrome Congenital adrenal hyperplasia Hyperaldosteronism Hypersecretion of adrenal androgens and estrogens Adrenocortical hypofunction Adrenal medulla hyperfunction
Cushing’s disease
Excessive anterior pituitary secretion if ACTH
Cushing’s syndrome
Manifestations resulting from chronic excess cortisol
Hyperaldosteronism
Primary (Conn’s syndrome) and secondary
Hypersecretion of adrenal androgens and estrogens
Feminization
Virilization
Adrenocortical hypofunction
Addison’s disease (primary adrenal insufficiency)
- addisonian crisis
Secondary hypocortisolism
Adrenal medulla hyperfunction caused by
Tumours derived from the chromaffin cells of the adrenal medulla
Diagnostic test for alterations of adrenal function
Lab tests: Hormone level Stimulation of suppression testing Imaging Biopsy
Antithyroid medications considerations
Better tolerated with food
Give at the same time everyday to maintain consistent blood levels
Do not stop abruptly
Avoid consumption of foods high in iodine
How to monitor therapeutic response of antithyroid medications
Thyroid drugs:
Decreased symptoms for hypothyroidism, improved energy levels, improved mental and physical stamina
Antithyroid drugs:
No evidence of hyperthyroidism
