Endocrine System Flashcards
Difference between the endocrine and nervous system
N: fast acting, short term
E: slow acting, fast term
A primary connection between the nervous and endocrine systems:
Hypothalamic-Pituitary Axis
Endocrine systems releases __ to affect ____ via the ____
Hormones to affect distant target cells with the appropriate receptor via the bloodstream
Endocrine gland
Ductless gland whose products are picked up by capillaries supplying blood to the region
Exocrine glands
Secrete products into the external environment by way of ducts which empty into the world or GI lumen
Hormone receptor
Polypeptide that possesses ligand-specific binding site
Binding of ligand ( ____ ) to the site causes the receptor to modify target cell activity
Tissue-specificity of hormone action is determined by
Hormone
Wether cells of a tissue have the appropriate receptors
Two classes of hormones:
Hydrophilic:
Hydrophobic:
Hydrophillic (peptides, AA derivatives) must bind to receptors on cell surface
Hydrophobic: (steroids) bind to cell interior
Peptide hormones are synthesized in the ___ and modified in the ____
They are stored in the ___ until they are needed
Rough ER
Golgi
Vesicles
When peptide hormones are ready to be used they are released by
Exocytosis
In the bloodstream, peptides dissolve in the ___ because they are:
Plasma
hydrophilic
Peptides hydrophilicity prevents them from crossing the cell membranes so they must communicate with the interior via a
Second messenger cascade which changes the function of proteins in the cytoplasm
A key feature of second messenger cascade is
signal amplification, which allows few activated receptors to change many enzyme’s activity in the cell
Because peptide hormones modify the activity of existing enzymes in the cytoplasm, their effects are exerted ____ and last ____
Rapidly
Short term
Two subcategories of the peptide hormone
Polypeptides and AA derivates (derived from single AA and have no peptide bonds)
Steroids are synthesized from ___ in ____
Cholesterol in smooth ER
Due to their ____, steroids can _____
Hydrophobicity
freely diffuse through the cell membrane
Since steroids diffuse through the cell membrane, they are not ___ but rather ____ as soon as they are made, so if a steroid hormone is not needed, ____
Stored
Diffuse into the blood stream
It won’t be made
Since steroids cannot be dissolved in the plasma, they journey through the bloodstream stuck to __ by ___
proteins by hydrophobic interactions
The small, hydrophobic steroid hormone exerts its effects upon target cells by
Diffusing through the plasma membrane to bind with a receptor in the cytoplasm
Once the steroid hormone diffuses in the cell and binds to its ligand, the hormone receptor complex
Is transported to the nucleus where it acts on transcription regulators to change the amount and type of protein in the cell
Since steroids change proteins transcription, their onset and extent of effects last
Onset: Slow (days)
Extent: Longer term effects (days to weeks)
Steroids regulating sexuality, reproduction and development are secreted by the:
Testes, ovaries and placenta
Steroids regulating water balance and other processes are secreted by
Adrenal cortex
All other endocrine glands (aside from the testes, ovaries, placenta and adrenal cortex) secrete
Peptide hormones
Thyroid hormone is derived from an amino acid, but its mechanism of action more closely resembles
Steroids
Specificity of peptides limits their action to target cells which have surface receptors on the cell membrane the exception is:
Thyroxine which is cytoplasmic
The flexible, automatic orderliness is attributable to
Feedback regulation
Physiological endpoint
Must be maintained at constant levels
Homeostasis
Physiological consistency (more long term than allosteric homeostasis)
Tropic hormones
Hormones that regulate hormones
Portion of the adrenal gland called the cortex
responsible for secreting cortisol and other steroids
Negative feedback or feedback inhibition
Result of hormone secretion inhibits further secretion
Most feedback in the endocrine system (and biochemical feedback) is
Negative
Hypothalamus
Instruct endocrine system by releasing tropic hormones that regulate other tropic hormones, called releasing and inhibiting factors/hormones
Releasing and inhibiting factors/hormones
Tropic hormones that regulate tropic hormones
Hypothalamic-pituitary portal system
Special circulatory system for efficient transport of hypothalamic releasing and inhibiting factors to the anterior pituitary
Hypophysis
Another name for pituitary gland
Pituitary gland has two halves
Front (anterior) and back (posterior)
Adenohypophysis
anterior pituitary
Neurohypophysis
posterior pituitary
Anterior vs posterior pituitary gland
anterior: normal endocrine gland controlled by hypothalamic releasing and inhibiting factors (esp. tropics)
post: composed of axons which descend from the hypothalamus (neuroendocrine cells)
Neuroendocrine cells
neurons which secrete hormones into the blood stream such as in the posterior pit. gland
The hormones of the posterior pit are
ADH which causes kidney eater retention during thirst and oxycontin (allowing milk for nursing and uterine contractions for labor)
Thyroid hormone and cortisol
Broad effects on metabolism and energy usage
Thyroid hormone is prod from the ____ and comes in two forms with 3 or 4
AA tyrosine
Iodine atoms per molecule
The prod of thyroid hormone is increased by:
Thyroid stimulating hormone from the anterior pituitary regulated from the hypothalamus and CNS
Mechanism of action for thyroid:
Bind to a receptor in the cytoplasm of cells that regulates transcription in the nucleus
Regulation effect INC overall metabolic rate, body temp and growth stimulation
Exposure to ___ can increase thyroid prod
Cold
Cortisol is secreted by the adrenal Cortex in response to ___ from the pituitary gland
ACTH
In general, cortisol helps the body
Deal with stress: provide energy during stress by mobilizing glycogen and fat stores and INC protein consumption
Removal of adrenal cortex and stress exposure
Death results
Long term levels of cortisol give negative effects such as
Suppression of the immune system
Adrenal gland is located
Near the pancreas
Hypothalamus
Hormone (class)
Target/effect
H: releasing and inhibiting factors (peptides)
T: Ant. pit / modify activity
Ant Pit
Hormone class: growth hormone
Effect
H: growth hormone (peptide)
More bone and muscle growth, more call turnover
Ant. Pit
Hormone class: prolactin
Target/effect
Prolactin (peptide)
Mammary gland/milk production
Ant. Pit (Tropic)
Hormone class: Thyroid stimulating hormone
Target/effect
TSH (Peptide)
Thyroid/ increases synthesis and release of TH
Ant. Pit (Tropic)
Hormone class: Adrenocorticotropic hormone (ACTH)
Effect
ACTH (peptide)
growth and secretory activity of adrenal cortex
Ant Pit (Gonadotropic)
Hormone class: luteinizing hormone (LH)
Target/effect
LH (peptide)
Ovary/ovulation, testes/testosterone synthesis
Ant Pit (Gonadotropic)
Hormone class: follicle stimulating hormone (FSH)
Target/effect
FSH (peptide)
Ovary/follicle development, testes/spermatogenesis
Posterior pituitary
Hormone class: Antidiuretic hormone (ADH, vasopressin)
Target/effect
ADH Peptide
Kidney/water retention
Post Pit
Hormone class: oxytocin
Target/effect
Oxytocin Peptide
Breast/milk letdown, uterus/contraction
Thyroid
Hormone class: Thyroid hormone (TH, thyroxine)
group/effect
Modified AA
Child: necessary for physical and mental development
Adult: higher metabolic rate and temp
Thyroid C Cells
Hormone class: calcitonin
Target/effect
calcitonin (peptide)
bone, kidney/ lowers serum (Ca2+)
Parathyroids
Hormone class: parathyroid hormone (PTH)
Target/effect
PTH (peptide)
Bone, kidney, small intestines/raises serum (Ca2+)
Thymus
Hormone class: thymosin
Group/effect
Thymosin (peptide)
Kids only
T cell development during childhood
Adrenal Medulla
Hormone class: Epinephrine
Effect
Epi (modified AA)
Rapid sympathetic stress response
Adrenal Cortex
Hormone class: cortisol
Effect
Steroid
longer term stress response, more blood (glucose), more protein catabolism, less inflammation and immunity
Adrenal Cortex
Hormone class: Aldosterone
Target/effect
Aldosterone (steroid)
Kidney/ more Na+ reabsorption to BP
Adrenal Cortex
Hormone class: Sex steroids
Effect
not normally important, but an adrenal tumor can overproduce these, causing masculinization or feminization
Endocrine pancreas
Hormone class: Insulin
Target/effect
Peptide by beta cells
less blood (glucose)/more glycogen and fat storage
Endocrine pancreas
Hormone class: Glucagon
Target/effect
Peptide
more blood glucose/less glycogen and fat storage
Endocrine pancreas
Hormone class: Somatosatin
Target/effect
peptide
inhibits many digestive processes
Testes
Hormone class: testosterone
Target/effect
Steroid
male characteristics, spermatogenesis
Ovaries/Placenta
Hormone class: estrogen
Target and effect:
steroid
female characteristics and endometrial growth
Ovaries/Placenta
Hormone class: pro-estrogen
Target and effect:
Steroid
endometrial secretion and pregnancy
Heart
Hormone class: ANF (atrial natriuretic factor)
Target and effect:
Peptide
Kidney/ inc urination to decrease BP
Kidney
Hormone class: erythrioietin
Target and effect:
Peptide
Bone marrow/RBC synthesis inc
