Endocrine System Flashcards
What are the differences between endocrine and exocrine glands?
Exocrine - Body surface (gets put out into body surface)
Endocrine - Secrete’s hormones directly into blood vessel, into blood stream (hormones travel the blood to get to target)
What are the body’s endocrine glands?
PRIMARY:
Thyroid
Parathyroid
Anterior & Posterior pituitary gland (Master endocrine gland)
Adrenal Glands
Pancreas (dual)
SECONDARY:
Ovaries & Testies
Hypothalamus
Heart
Liver
Kidneys
Blood Vessels
Adipose Tissue
Pineal
Stomach and Small Intestine
Major classes of hormones
Amine Hormones: come from amino acids (small)
Thyroid hormones: Thyroxine, Triiodothyronine
Catecholamines: Norepinephrine, Epinephrine
Peptide Hormones: amino acid chains
ACTH (adrenocorticotropic hormone)
HGH (Human growth hormone)
Steroid Hormones: Made from cholesterol
Cortisol (stress)
How are peptide and protein hormones synthesized?
Preprohormone -> Prohormone -> Hormone
How are steroid hormones synthesized
Receive signal to make hormone -> Activates Proteins -> Takes cholesterol -> converts to Final Steroid hormone -> directly diffuses into blood stream (slips through membrane)
CAN NOT BE STORED
Examples of steroid hormones
(not as important, know how it all can be connected)
Cholesterol ->
Androgens (Masculine associated effects):
With Aromatase -> estrogens
Corticosterone & Cortisol: stress hormones
Aldosterone: Sodium regulation
Progesterone
Why and how are hormones removed from circulation?
To prevent oversignaling (like removing neurotransmitters)
Excretion by urine
Inactivated by metabolism
Activated by metabolism, binds to target cells -> More metabolism inactivates, excretion
How do different types of hormones have their effect on a target cell?
Nonsteroid hormone: second messenger
Steroid hormone: Changes gene transcription
Target specificity
Target cell: has the receptor for the hormone
Non-target cell: do not have the receptor
Target Sensitivity
Upregulation: Increase target sensitivity by putting more receptors
Downregulation: Decrease target sensitivity by decreasing # of receptors
Permissive Action
The impact one hormone has on another
Example: Thyroid hormone has permissive effect on epinephrine, allowing a large amount of fatty acids to be released in adipose cell.
How? Increase B adrenergic receptors.
Effect: Thyroid hormone -> Increase B adrenergic receptors -> Makes cell more sensitive to epinephrine
How do ions control hormone release?
Example: Increase in glucose causes increase in insulin.
so decrease in glucose decreases insulin
How do neurons control hormone secretion?
Central Nervous System:
Directly stimulates endocrine gland
Neuron releases hormone (tropic hormone) causes stimulation of gland
Neurohormone released directly by neuron (Neuron releases the hormone)
How do tropic hormones control hormone secretion?
Tropic hormone - Influences release of another hormone
Endocrine Disorders
2 basic categories of symptoms, caused by 3 different causes each
Too Much Hormone vs Too Little Hormone
Primary Hypersecretion, Primary Hyposecretion, Secondary Hypersecretion, Secondary Hyposecretion, Hyper Responsiveness, Hypo Responsiveness
LEARN HORMONE, TROPIC HORMONE, AND RECEPTORS INCREASING OR DECREASING
Hypothalamus & Posterior Pituitary relation
Hypothalamus (neural circuit) - involved in homeostasis.
Infundibulum (connecting spot) takes neurons and blood vessels from the brain to the pituitary
POSTERIOR PITUITARY : Neural tissue & blood vessels
Everything that happens from posterior pituitary is originating in the hypothalamus
Functions of Posterior Pituitary Hormones
Oxytocin: Uterine muscles, mammary glands -> Reproductive Chapter
ADH (Antidiaretic hormone/Vasopressin) -> Blood pressure regulation -> Renal Chapter
Hypothalamus & Anterior Pituitary
Infundibulum -> Median Eminence -> Dumps neurohormones (tropic hormones) into Hypothalamo-hypophyseal portal vessels -> Tropic hormones cause change in hormone secretion -> Release hormones into blood stream
Anterior Pituitary Gland Hormones
Endorphins - Decrease pain perception
Prolactin - Prepare for lactation
Growth Hormone - Growth and Development
FSH and LH (Gonadotropins) - Produce sperm & ova
ACTH (adrenocorticotropic hormone) - Stress response
TSH (Thyroid stimulating hormone) - Increase thyroid hormone
Hormones and what they cause
CRH -> ACTH
TRH -> TSH
GHRH -> GH
GnRH -> LH and FSH
SST -> Inhibits GH
Dopamine -> Inhibits Prolactin
Prolactin -> Inhibits FSH and LH, and GnRH
How is Hormone release by hypothalamus and anterior pituitary gland controlled?
Stimulus (stress) -> CRH -> hypothalamo-hypophyseal portal vessels -> ACTH -> throughout the body (general circulation) -> Cortisol (prevents hypersecretion) -> Targets cells for stress response
What are the pathways controlling release of growth hormones
Stimulus -> Hypothalamus (GHRH secretion, and decrease in somatostatin) -> Hypothalamo-hypophyseal portal vessels -> Anterior pituitary (increase GH secretion) -> General circulation -> Liver and other cells (increase in insulin like growth factor) -> Increase growth -> Increase bone length and increase protein synthesis
Feedback loop for growth hormone
Insulin like growth factor - 1: stimulates GHRH, stimulates SST
GHRH stimulates GH
SST inhibits GH
GH simulates Insulin like growth factor - 1
Abnormal growth hormone secretion
DURING CHILDHOOD ADOLESCENCE
Too little GH - Pituitary Dwarfism
Too much GH - Pituitary Gigantism
DURING ADULTHOOD
Acromegaly - Too much GH causes face to thicken, bones in face and hands and feet grow.
Other hormones affecting growth
Postnatal: Growth Hormone - Stimulates liver to secrete IGF - 1, stimulates protein synthesis
Prenatal: Insulin - Fetal growth, little bit of postnatal growth
Thyroid hormone - Increase GH receptors (permissive action)
Testosterone, Estrogen - Puberty growth, stimulates secretion of GH, causes a burst of growth, then a cessation of growth
Cortisol - Inhibits growth, stimulates protein catabolism (breaking down) allows us to regulate growth speed
Location and structure of the thyroid gland
Follicular cells - thyroid hormone
Follicle Lumen - colloid, protein rich tyrosine
Thyroid follicle - made up of follicular cells and follicle lumen
Parafollicular cells - c cells - make calcitonin
How are thyroid hormones synthesized?
- Iodide is cotransported with Na+
- Diffusion through the follicle cell into the lumen (colloid)
- Iodide attaches to the ring in tyrosine (Thyroglobulin)
- The iodinated ring is added to another ring. (T3, or T4)
- Endocytosis of thyroglobulin containing T3 and T4 molecules
- Lysosome added, releasing T3 and T4
- T3 and T4 secretion (diffuses lipophylic)
T3 form is more active
T4 form is less active
Thyroid hormone cant be stored
Thyroid Process how is it controlled
Hypothalamus -> Hypothalamo - hypophyseal portal vessels -> Anterior Pituitary (TSH secretion)-> general circulation -> Increase thyroid hormone secretion -> General circulation -> Target cells cell response
What are the effects of Thyroid hormone
Increased metabolism
Increase IGF - 1 & protein synthesis
Increase dendrite and axon growth & synapse formation
Increased catecholamine effect
Increase in B adrenergic receptors (epinephrine)
What are the symptoms of Hypothyroidism
Decreased Metabolic rate
Decreased catacholamine effects
Myxedema - build up of glycosaminoglycons in the interstitual fluid
Goiter - enlarged thyroid gland - Primary hyposecretion
Hyperthyroidism
Increased metabolic rate
Increased appetite
Increased catecholamine effect
Decrease in free testosterone
Myxedema - prolonged hyperthyroidism
Goiter - overstimulating and overproducing
What hormones do the medulla and cortex of the adrenal glands secrete?
Medulla -> Epinephrine and Norepinephrine
Cortex -> 3 layers, each produce different hormones
Aldosterone (blood Na control)
Cortisol & small amount of androgens
Androgens & small amount of cortisol
What is the HPA axis and how does it help the body deal with stress?
HPA axis - Hypothalamic Pituitary Adrenal axis
Permissive effect on catecholamines
Inhibits inflammation and specific immunity
Permissive effect on growth hormone
Inhibits non essential functions
How does negative feedback control activity of the HPA axis?
Hypothalamus (increase CRH secretion) -> Hypothalamo - hypophyseal portal vessels -> Anterior pituitary (increase ACTH secretion) -> general circulation -> Adrenal cortex (increase cortisol secretion) -> General circulation -> Response to increase cortisol.
Increase cortisol causes negative feedback for ACTH and CRH secretion.
What are the symptoms of insufficient cortisol production
Less sensitive to epinephrine
Decrease Liver function
Weakness
Weight loss
Addisons disease (bronze pigmentation and changes in body hair)
What are the symptoms of excess cortisol production
Decreases immune system
Decreased catecholamine permissive effect
Inhibition of nonessential functions
Increase energy mobilization and disregulation in fat storage
Increase androgens
Cushings disease (tumor)
