Endocrine System Flashcards
The endocrine system uses ____ to communicate?
Hormones
What is a Hormone?
A hormone is a chemical messenger that travels in the bloodstream to other tissues or organs to stimulate physiological responses in cells of another tissue or organ
What are the 4 principal mechanisms of communication between cells in the body?
GNPH
Gap junctions
Neurotransmitters
Paracrines
Hormones
What are gap junctions and where are the commonly found?
The are pores in cells that allow signaling molecules, nutrients, and electrolytes to move from cell to cell.
Used by smooth and cardiac muscle
What are paracrines?
The are short acting hormones released by cells to affect a local area
The endocrine system is composed of what?
Hormone producing glands, tissues, and cells
What are exocrine glands?
Glands with ducts that secrete substances to an epithelial surface “external secretions”
What are endocrine glands?
Glands with ducts that secrete hormones into the body “internal secretions”
Composed of dense fenestrated capillary networks which allow easy uptake of hormones by the blood
What are three neurotransmitters that also act as hormones?
AND
Antidiuretic hormone (ADH)
Nor-epinephrine
Dopamine
Where is the pituitary gland located?
inferior to the hypothalamus suspended by the infundibulum and housed in the stella turcica of the sphenoid bone
What two structures make up the pituitary gland?
The anterior and posterior pituitary gland
Adenohypophysis and the Neurohypophysis
How is the anterior lobe of the pituitary gland connected to the hypothalamus?
Via the hypophyseal portal system
What is the hypophyseal portal system?
A network of capillaries that begins in the Hypothalamus and travel into the anterior lobe via portal venules
how Is the posterior lobe of the pituitary gland different?
It is actually an extension of the nervous system it communicates via neurons that originate in the hypothalamus
How many hormones are produced in the hypothalamus?
8
How many hypothalamus hormones regulate the anterior pituitary lobe?
6
4 releasing and two inhibiting
What are the four releasing hormones that stimulate the anterior pituitary
TCGG
TRH-Thyroid Releasing Hormone
CRH- Corticotropin Releasing Hormone
GnRH- Gonadotropin Releasing Hormone
GHRH- Growth Hormone Releasing Hormone
What are the two inhibiting hormones that inhibit the anterior pituitary lobe?
PS
PIH - Prolactin Inhibiting Hormone
Somatostatin - Inhibits GH and TSH secretion
What two Hormones are released by the posterior pituitary lobe?
OA
OT- Oxytocin
ADH- Antidiuretic Hormone
What does “Tropic” mean?
It controls other glands
How many hormones does the posterior lobe of the pituitary lobe synthesize?
None but it stores two from the hypothalamus
How many hormones doe the anterior lobe of the pituitary lobe synthesize?
What are they?
FLTAPG
6 FSH- follicle-stimulating hormone LH- luteinizing Hormone TSH- Thyroid Stimulating Hormone ACTH- Adrenocoritcotropic hormone PRL- Prolactin GH- growth hormone
The Paraventricular nuclei of the hypothalamus produce what hormone?
Oxytocin
OT
The Supraoptic nuclei of the hypothalamus produce what hormone?
Antidiuretic hormone
ADH
What two Hormones are released when GNRH is produced?
FL
Follicle-Stimulating hormone (FSH) Luteinizing Hormone (LH)
What hormone is FSH and what is its general function?
Follicle-Stimulating hormone
Stimulates secretion of ovarian sex hormones, development of ovarian follicles, and stimulates sperm production in males
What hormone is LH and what is its general function?
Luteinizing Hormone
Stimulates ovulation, stimulates the corpus luteum to produce progesterone, and stimulates the testies to produce testosterone
What hormone is released in the presence of TRH?
Thyroid-stimulating hormone (TSH)
What hormone is TSH and what is its general function?
Thyroid stimulating hormone
Stimulates secretion of thyroid hormone
What hormone is released in the presence of CRH?
ACTH (Adrenocorticotropic hormone)
What hormone is ACTH and what is its general function?
Adrenocorticotropic hormone
Stimulates the adrenal cortex to secrete glucocorticoids (cortisol)
What hormone stimulates the release of Prolactin?
TRH
What hormone is PRL and what is its general function?
Prolactin
Stimulates mammary glands to produce milk
What hormone is released in the presence of GHRH?
GH
Growth Hormone
What Hormone is GH and what is its general function?
Growth hormone
Stimulates mitosis and cellular differentiation
What hormone is ADH and what is its general function?
Antidiuretic Hormone
Increases water retention, reduces urine volume to prevent dehydration
also know as vasopressin because it is a vasoconstricter
increases BP
What are the functions of OT
Oxytocin
promotes sexual satisfaction
stimulates labor contractions via positive feedback
stimulates the flow of milk
promotes bonding between child and mother
Are the rates of hormone release constant?
no
What are the four main targets of GH?
Cartilage, bone, muscle, fat
When GH reaches the liver what does it induce?
it causes the liver to produce growth stimulants
IGF-1
IGF-2(somatomedins)
What do IFG-1 and IGF-2 do?
Stimulate target cells prolong the action of GH increase protein synthesis increase lipid metabolism (protein sparing effect) Stimulates glucose release from liver Reduce dependence of other cells on glucose (glucose sparing effect) Balance electrolytes
Hormone Half life is defined as-
The amount of time it takes for 50% of the hormone to be cleared from the blood
What is the half life of GH?
6-20 minutes
What is the half life of IGF-1?
20 hours
How does GH affect bone growth?
it cause thicker bones and induces remodeling
What causes the release of ghrein and how does it effect GH?
and empty stomach
activates GH
Where is the pineal glad located?
the roof of the third ventricle of the brain
When does the pineal gland begin to shrink?
around age 7
What is the assumed function of the pineal gland?
Synchronization of circadian rhythms
Synthesizes melatonin from serotonin
influences the time of puberty
What three body systems does the thymus play a role in?
Endocrine
Lymphatic
Immune
Where is the thymus located?
Superior to the heart
What important cell matures in the thymus?
T cells
What is function of the thymus?
secretes hormones that stimulate the development of lymphatic organs and the activity of T lympocytes
Where is the thyroid gland located?
Inferior to the larynx
Most of the thyroid is made up of thyroid ____ which are?
Thyroid follicles
sacs lined with simle cuboidal epi cells that contain colloid
What hormones does the thyroid glad produce and secrete? their funtion?
Thyroxine (T4)
Triidothyronine (T3)
Responsible for metabolism in virtually all cells
Between the follicles of the thyroid are ____ cells also called C cells. What is their function?
Parafollicular cells
the secrete calcitonin
What is the function of calcitonin?
stimulates osteoblast activity and bone formation
Where are the parathyroid glands located?
embedded in the posterior surface of the thyroid gland
What hormone is secreted by the parathyroid glands and what is its function?
PTH (parathyroid hormone)
- Increases blood Ca++ levels
- Promotes synthesis of calcitriolactive Vit D
- increases absorption of Ca++
- Decreases urinary excretion
- increases bone reabsorbtion
The adrenal medulla consists of _ to _ % of the adrenal gland
12-20%
The adrenal medulla is primarily a part of the ___ system?
sympathetic nervous system
The adrenal medulla consists of postganglionic neurons called____cells
chromaffin cells
When the adrenal medulla is stimulated it releases ____ directly into the blood stream
Catecholamines
What are the two Catecholamines released by the adrenal medulla?
Epinephrine and nor-epinephrine
What are the three main effects that catecholamines have on the body?
ABD
- Alerts the body and prepares it for physical activity
- Increases Vitals, Airflow, and metabolic rate
- Decreases Digestion and Urine
How do catecholamines prepare the body for activity?
- Mobilizes high energy fuels, lactate, fatty acids, glucose
- boosts glucose levels but initiating Glycogenolysis and Glucogenesis in the liver
- Epi inhibits insulin to spare glucose for the brain
*basically, it causes your body to produce more glucose and spare it for use by the brain while making high energy fuels available for the rest of the body
the Adrenal cortex is the ___ portion of the adrenal gland and is part of the ___ system
Outer
Endocrine
The main function of the adrenal cortex is to secrete ____ hormones
Corticosteriods
How may layers does the adrenal cortex have? What are they? super to deep
GFR
Zona glomerulosa
Zona fasciculata
Zona reticularis
Describe the zona glomerulosa and list its function
Thin outer layer of the cortex
cells arranged in round clusters
secretes mineralocorticoids that regulate the body’s electrolyte balance
Describe the zona fasciculata and list its function
Thick middle layer
Cells arranged in fascicles separated by capillaries
Secretes glucocorticoids cortisol as well as a small amount of androgens
Describe the zona reticularis and list its function
Narrow inner layer
cells in branching network reticulated
secretes glucocorticoids and sex steroids androgens
Glucocorticoids are secreted by the ____ and ___ of the adrenal ___
Zona Fasciculata and reticulata
cortex
Glucocorticoids function to____
regulate metabolism of glucose and other fuels
Glucocorticoids are released in responce to the hormone _____ which is released by ___ from the ___ gland
ACTH
CRH
anterior pituitary
The Glucocorticoids cortisol and corticosterone stimulate what 3 things?
FGF
Fat/protein catabolism
gluconeogenesis
release of fatty acids and glucose
What effect do Glucocorticoids have on the body that can suppress the immune system with long term exposure?
the anti-inflammatory effects can suppress the immune system
What are the two main sex steroids released by the adrenal cortex?
Androgens and Estradiol
What is the general function of Androgens?
they set libido
play a large role in prenatal male development
are the cortex and medulla of the adrenal gland functionally independent?
no
What happens to the medulla of the adrenal gland in the absence of cortisol?
it atrophies
How do the cortex and the medulla work together?
some of the chromaffin cells of the medulla extend into the cortex and stimulate it to release corticosteroids when stress activates the sympathetic nervous system
What are the three main endocrine cells located within the pancreatic islets?
Alpha
Beta
Delta
What hormone is secreted by the alpha cells of the pancreatic islets?
Glucagon
What is the function of glucagon? when is it released
- It is released between meals when blood glucose is falling and when amino acid levels are rising in the blood
- in the liver it stimulates glycogenolysis, gluconeogenesis, and the release of glucose into the blood stream
- in adipose tissue it stimulates fat catabolism to release fatty acids
- in the blood when amino acid levels rise to promote absorption
What hormone is secreted by the beta cells of the pancreatic islets?
Insulin
What is the function of insulin? when is it released?
- It is released during and after meals when glucose and amino acid levels are rising
- It stimulates cells to absorb, store, and metabolize glucose
- promotes synthesis of fat, protein, and glycogen
What parts of the body do not need insulin to absorb glycogen?
Brain, liver, Kidneys, and RBC’s
The insufficiency of insulin is called?
type one diabetes mellitus
The inaction of insulin is called
type two diabetes mellitus
What hormone is secreted by the delta cells of the pancreatic islets?
Somatostatin
What is the function of somatostatin?
- it partially suppresses secretion of glucagon and insulin
- it inhibits nutrient digestion and absorption effectively prolonging the absorption of nutrients
What are the 5 main hyperglycemic hormones?
GGENC
Glucagon Growth hormone Epi Nor-epi Cortisol
What are the endocrine products of the gonads?
gonadal hormones
What are the exocrine products of the gonads?
eggs and sperm
What are the three main Ovarian hormones?
Estradiol, progesterone, and inhibin
What are the four main testicular hormones?
Testosterone, weaker androgen’s, estrogen, and inhibin
What cells within the ovary will synesize androstenedione (estradiol and progestrone precursor)
The Theca cells
What cells convert androstenedione into estradiol and progestrone?
granulosa cells
What becomes of the ovarian follicle after ovulation?
It becomes the corus luteum
What is the function of the corpus luteum?
it produces progestrone for 12 days to help support possible pregnancy
The follicle and the Corpus luteum also produce what hormone to assist in the entire process?
Inhibin
What are the three main functions of progestrone and estradiol?
- Development of female reproductive system
- regulation of menstrual cycle, and to sustain pregnancy
- prepare mammary glands for lactation
what hormone does inhibit inhibit?
FSH
Which portion of the testes produce sperm?
the semiferous tubules
Where are the nurse cells of the testes located?
the tubule walls
What cells lie in clusters between the tubules of the testes?
interstital cells ( leydig cells)
Where is testosterone produced in the testes?
from the interstital cells
What is the function of testosterone?
stimulates the development of male reproductive system
sustains sperm production
Where is inhibin produced in males?
nurse cells of the testes
What is the endocrine function of the skin?
UV light causes keratinocytes to produce cholecalciferol which is a cholesterol-like steroid precursor to Vit D
What happens to cholecalciferol after it is produced in the skin?
it is converted to calcidiol by the liver
what happens to calcidiol after it is converted from cholcaliferol in the liver?
it is converted to calcitriol by the kidneys
What are the functions of mineralocorticoids from the adrenal cortex?
Regulates electrolyte balance
Aldosterone stimulates Na+ retention and K+ excretion which causes water retention to maintain BP and blood volume
The ___ secretes 15% of erythropoietin
liver
What is the function of erythropoietin?
stimulates bone marrow growth and hemopoiesis
What is the sorce of IGF-I
the liver
What is the function of hepcidin?
promotes intestinal absorption of iron
The kidneys are responsible for the production of what three hormones?
Calcitriol
Renin
85% of erythropoietin
What is the function of Renin?
It converts angiotensinogen to angeotensin I
What happens to Angeotensin I
it is converted into angeotensin II by the ACE enzyme in the lungs
What is the function of Angeotensis II?
it is a vasoconstrictor that raises BP
What endocrine functions does the heart have?
it produces two natriuretic peptides in response to high BP
What is the function of the natriuretic peptides produced by the heart in response to high BP?
They decrease BP and blood volume by increasing Na+ and H2O output by the kidneys
opposing action to angiotensin II
How many hormones are produced by the digestive system?
10
What is the main function of digestive hormones?
To coordinate digestive motillity and glandular secretion
What hormone is secreted by adipose tissue? its function?
Leptin
slows appetite
What hormone is produced and secreted by osseous tissue? its function?
Osteocalcin secreted by osteoblasts
- increases the number of pancriatic beta cells, output of insulin, and insulin sensitivity
- inhibits weightgain
What hormones are produced by the placenta? their general function?
Estrogen, progestrone, and others
Regulate pregnancy, stimulate development of fetus and mammary glands
What are the three chemical classes of hormones?
Steroids
monoamines
peptides/glycoproteins
What are steroids?
Examples?
hormones derived from cholesterol
they can pass through plasma membranes because they are lipid based
*testostrone estrodiol, cortisol
What are monoamines?
examples?
Hormones made from amino acids
Dopamine, epi, nor-epi,melatonin, thyroid hormone*
What are peptides/glycoproteins?
examples?
created from chains of amino acids
hormones from the pituitary and hypothalamus
insulin
How are steroids synthesized?
from cholesterol
How are peptides synthesized?
the same way any protein is
How and where is a peptide hormone modified after it is translated?
in the ER and the Golgi
How are monoamines synthesized?
-Melatonin is made from the amino acid tryptophan
others come from the amino acid tyrosine
Why is thyroid hormone lipid soluble?
because it is composed of two tyrosines
In the thyroid, once follicular cells absorb iodide ions from the blood what do they do?
oxidize them to a more reactive form
In the thyroid, what protein do the follicular cells produce and where do they store it?
thyroglobulin (Tg) to be stored in the follicle lumen
In the thyroid, how are the forerunners of T3 and T4 made?
Iodine atoms are added to tyrosines withinn Tg and link together
In the thyroid, how are T3 and T4 produced?
whe TSH reaches the follicle cell, it absorbes Tg (with attached iodine atoms) and splits them with lysosomal enzymes releasing T3 and T4 from the basal side of the follicle cell
What are the 3 types of stimuli that influence the release of hormones?
Neural
Hormonal
Humoral
What is Humoral stimuli?
blood borne stimuli
rise and fall of different subsences in the blood trigger hormone release
Why cant steroid hormones be produced and stored?
because they are lipid soluble and can diffuse through plasma membranes
Most monoamines and peptides mix with blood plasma easily because they are _____
hydrophilic
How are steroids and thyroid hormone transported in the body?
Via transport proteins
Why do bound hormones have a longer half life?
because they are protected from liver enzymes and kidney filtration
Where are transport proteins synthesized?
the liver
What are some transport proteins?
albuin, thyretin, thyroxine-binding globulin (TGB)
What is the transport protein for cortisol?
transcortin
What are hormone receptors composed of?
Proteins or glycoproteins
Which hormones have receptors inside the cells?
steroids
How does Thyroid hormone enter cells?
ATP-dependent transport proteins
What happens to T4 after entering the cell?
it is converted into T3
What is the function of T3?
it binds to nuclear receptors and activates genes for the sodium potassium pump
How do peptides and catecholamines activate cells?
via second messenger systems
Explain hormone signal amplification
One hormone molecule can activate many enzyme molecules and produce a large effect
How is target-cell hormone sensitivity adjusted?
by changing the number of receptors
If the number of hormone receptors is up-regulated than___
hormone sensitivity is increased
What is a cause of Down-regulation of hormone receptors?
Long term exposure to high hormone concentrations
What is a hormonal synergistic effect?
Example?
When multiple hormones act together for a greater effect.
FSH + Testosterone create large sperm production
What is a permissive hormonal effect?
example?
when one hormone increases a target hormones response to a later hormone
Estrogen prepares the uterus for the action of progesterone
What is a hormonal antagonistic effect?
example?
One hormone opposes the action of another
insulin lowers blood glucose and glycogen raises it
How are hormones cleared from the body?
By the liver and kidneys
What is the MCR of hormones?
the metabolic clearance rate
rate of removal from the blood
What is stress?
a situation that upsets homeostasis and threatens ones physical or emotional well-being
What is GAS in terms of stress
GAS stands for General adaptation syndrome
it is the consistant way that the body reacts to stress that occurs in three stages
What are the three stages of General adaptation syndrome?
Alarm reaction (30 seconds)
Stage of resistance (30 minutes)
Stage of exhaustion(30 days)
What is the Alarm reaction?
your body’s initial response to stress as it prepares for fight or flight
What hormones mediate the alarm reaction and where do they come from?
norepinephrine from the sympathetic NS
Epinephrine from the adrenal medulla
What occurs in the body during the alarm reaction
Stored glycogen is consumed
BP is raised by angiotensin
Aldosterone causes water and Na+ retention also raising BP
Basiclly BP and BG are increased
What stage comes after the alarm reaction?
the stage of resistance
What occurs in the body during the stage of resistance? (General)
- Glycogen stores are depleted so the body provides pathways to create more
- Cortisol is the main player here as it spares glucose for the brain and promotes the catabolism of fat and protein to create more glucose
The stage of exhaustion is reached when stress contines for _____ and ___ reserves are gone
several months
fat reserves
What occurs during the stage of exhaustion?
Death and decline
- Fat stores are depleted
- muscles have been broken down for glucose
- Adrenal cortex stops functioning which causes a loss of glucose homeostasis
- Large amounts of K+ lost leads to hypokalemia from aldosterone productions
What are paracrines?
Chemical messengers that diffuse short distances and stimulate nearby cells
What are the three types of paracrines?
Histamine
Nitric oxide
Catecholamines
what are the main histamine producing bodies?
Mast cells in connective tissue
Where does nitric oxide come from?
the endothelium of blood vessels
What is the action of histamines?
relaxation of blood vessels
What is the action of nitric oxide?
vasodilation
Where do catecholamines come from?
They diffuse from the adrenal medulla to its cortex
What is an autocrine?
a chemical messenger that stimulates the same call that secretes it.
What acid are Eicosanoids paracrine family derived from?
A fatty acid called arachidonic acid
Where does arachidonic acid come from?
it is made from the phosolipid by-layer of cells plasma membranes.
What paracrine is produced when lipoxygenase converts arachidonic acid?
Leukotrienes
What is the function of Leukotrienes?
The mediate allergic and inflammatory reactions
What 3 eicosanoid paracrines are produced when Cyclooxygenase (COX) converts arachidonic acid?
PTP
Prostacyclin
Thromboxanes
Prostaglandins
What is the action of Prostacyclin?
Inhibits blood clotting and vasoconstriction
What is the action of Thromboxanes?
- Produce platelets after injury
- overrides prostacyclin***
- stimulates vasoconstriction and clotting
What are the two Prostaglandins? and their actions?
PGE- Relaxes smooth muscle in bladder, intestines, bronchioles, uterus, stimulates contraction of blood vessels
PGF- Opposite effect of PGE
How does cortisol act against inflammation?
It is a (SAID)
It and other corticosterones inhibit inflammation by blocking the release of arachidonic acid and inhibits the synthesis of eicosanoids
What are the disadvantages of using SAIDs
They produce symptoms of cushings disease
Howdo NSAID’s act against inflammation?
- inhibits COX
- does not block leukotriene production
Why are NASID’s good at treating thrombosis?
Because the block COX and as a result inhibit the production of Prostaglandin and Thromboxane blood clotting
What is endocrine Hyposecretion? what are some causes?
inadequate hormone release
- tumor or trauma destroy or injure hormone producing bodies
- Autoimmune disorders
What is endocrine Hypersecretion? what are some causes?
Excessive hormone release
Tumors or autoimmune disorders
What is a toxic goiter (graves disease)?
Autoimmune disorder where antibodies mimic the effect of TSH on the thyroid causing hypersecretion of TH
What is acromegaly?
thickening of bones and soft tissue in adults due to hypersecretion of GH
What is Myxedema?
Adult hypothyroidism
What is a goiter?
enlarged thyroid glad due to the body not producing TH caused by iodine deficiency
What is a fatal symptom of Hypoparathyroidism?
Fatal tetany (Spasms in larynx) due to loss of calcium levels in the blood
What are some symptoms of Hyperparathyoidism
Soft bones due to excess leeching
blood Ca2+ and phosphate levels increase
Excess blood Ca++ promotes renal calculi formation
What is cushing syndrome?
Excess cortisol secretion
- Causes hyperglycemia, weakness, edema
- rapid bone and muscle loss due to cortisol promoting catabolism of bone and proteinglucose sparing effect
- Abnormal fat depositionmoon face buffalo hump
What is Adrenogenital syndome(AGS)?
- accompanies cushings disease*
- Adrenal androgen hypersecretion
- Enlargement of external sex organs in children and causes early onset puberty
- Has masculizing effects of women
What is Diabetes Mellitus? general
DIsruption of metabolism due to hyposecretion or inaction of insulin
What are symptoms of Diabetes Mellitus?
-Polyuria (excessive urination)
Polydipsia (intense thirst)
Polyphagia (Hunger)
All caused by the excess of glucose in the blood
What is the difference between type 1 and type 2 diabetes?
Type one is due to the the bodies immune system attacking beta cells in the pancreatic islets causing the under production of insulin
Type 2 is dues to resistance to insulin that the body produces -caused by many factors including inactivity, poor diet, also could be genetic and it can be sured
What occurs when cells are unable to absorb glucose?
then they must rely on fat and protein for energy resulting in weight loss and weakness
What causes the production of ketones in the blood. how?
The catabolism of fat releases ketones and fatty acids from stored fats
What are the negative effects of the production of excessive ketones?
Ketonuria_loss of Na+ and K+ leads to irregular heartbeat and neurological issues.
Ketoacidosis- ketones are acidic and will decrease the pH of the blood
What is a main observable symptom of ketoacidosis?
Deep gasping breaths as the body tries to increase the pH of the blood
What are the results of chronic hyperglycemia?
Neuropathy
arterial damage to kidneys and retinas
atherosclerosis