Outcome 7 - Endocrine System Flashcards
Which system also works together with the endocrine system?
nervous
What is the difference between what the kind of mediator molecules the nervous system releases and which the endocrine system releases?
NS - neurotransmitters
ES - hormones
What are the target cells for NTs? Hormones?
NTs - muscle cells, gland cells and other neurons
ES - cells throughout body
______ responses are slower but usually have longer effects.
Endocrine
What is a key difference between NS and ES in terms of what/where their mediators are regulating?
NS - specific muscles/glands
ES - aids in regulation of all types of body cells
Neurotransmitters released ______ as a response to _______ ________.
whereas, hormones are delivered to ____ throughout the body by _____.
NT - locally as a response to nerve impulses
hormones - tissues throughout body by blood
Where is the site of mediator action in the NS? ES?
NS - close to the site where it was released (synapses)
ES - usually farther from site of release
Where do endocrine glands secrete their products?
into the interstitial space that surround the secretory cells
What are some examples of endocrine glands?
pituitary, thyroid, parathyroid, adrenal and pineal glands
Are endocrine glands vascular or non-vascular?
they’re highly vascular!
Are endocrine glands the only ones that secrete hormones?
No.
What are the four characteristics of receptors?
1) made of protein and when hormones bind to it, they result regulation
2) they’re constantly broken down and resynthesized
3) down regulation – excess hormones = # of receptors to decrease
4) up regulation – deficient of hormones = # of receptors to increase
What is up regulation?
when there is deficient hormone present and the number of receptors increase
What is down regulation?
when there is excess hormone present which leads to the number of receptors to decrease
What type of hormones are there?
- circulating
- local
What are the two types of local hormones?
1) paracrine
2) autocrine
What are paracrine hormones?
they effect neighbouring cells
What are autocrine hormones?
they effect cells that secrete them
What are circulating hormones?
- they are secreted into the interstitial space
- they diffuse into blood to allow for circulation through the body
What are the two classes of hormones?
1) Lipid-soluble
2) water-soluble
What are the three subdivision of the two classes of hormones?
Lipid-soluble:
1) steroid
2) thyroid
3) gas
water-soluble:
1) amines
2) peptides
3) proteins
What are some examples of steroid hormones?
- aldosterone, cortisol, androgens, calcitriol, testosterone, estrogens, and progesterone
What are some examples of thyroid hormones?
T3 and T4
What are some example of gas hormones?
Nitric oxide, prostaglandins and leukotrienes
What are some examples of amine hormones?
E/NE, melatonin, histamine, and serotonin
What are examples of peptides and proteins?
all hypothalamic releasing and inhibiting hormones
How do water-soluble hormones travel? Lipid-soluble?
water - hydrophilic therefore, circulate freely in watery blood plasma
lipophilic - bound to transport proteins
What do transport proteins do?
- they make hormones temporarily water-soluble
- they slow the rate of loss in the urine
- provide a ready reserve of hormone
What is free fraction?
0.1-10% of lipid-soluble hormones that aren’t bound to a transport protein and will diffuse out of the blood stream and bind to receptors to trigger responses
How do you begin the mechanism of action?
lipid-soluble hormones bind to receptors INSIDE the target cells
water-soluble hormones bind to part of target cell plasma membranes (OUTSIDE)
What are the three steps for the lipid-soluble MOA?
1) lipid-soluble hormone diffuses into cell
2) activated receptor-hormone complex alters gene expression
3) newly formed mRNA directs synthesis of specific proteins on ribosomes
What are the 5 steps for the water-soluble MOA?
1) binding of hormone (first messenger) to its receptor activates G protein – activates adenylate cyclase
2) adenylate cyclase converts ATP to cAMP
3) cAMP (2nd messenger) activates the protein kinase
4) protein kinase phosphorylate cellular proteins
5) phosphorylated proteins cause rxns that produce physiological responses
What are the 3 things that hormone interactions depend on?
1) hormones in blood
2) # of hormone receptors on the target cell
3) influence of other hormones on the target cells
What do permissive effect hormones do?
- increase the number of receptors on the cells
- create an enzyme to catalyze the reaction of the 1st hormone
What is synergistic effect?
when the effects of two hormones acting together is greater than the sum of the effects of each individual hormone
What is an example of two hormones who show synergistic effect?
epinephrine and glucagon
What is an example of hormones that show permissive effects?
epinephrine and T3+T4
What is antagonistic effect?
when one hormone opposes the action of another
What is an example of antagonistic hormones?
insulin and glucagon
What are the 3 ways in which hormone secretion is regulated?
- signals from the nervous sytem
- chemical changes in blood
- other hormones
______ controls the secretions of the _____________.
hypothalamus controls … pituitary gland
What is another word for the pituitary gland?
hypophysis
What does the hypothalamus and pituitary do?
regulate growth and development, metabolism and homeostasis
Where do you find the pituitary gland?
in the hypophyseal fossa of the sella turcica
How does the pituitary attach to the hypothalamus?
infundibulum
What are the two lobes of the pituitary?
1) adenohypophysis (anterior)
2) neurohypophysis (posterior)
What are the 4 regions of the hypothalamus?
- mammillary region
- tuberal region
- supraoptic region
- preoptic region
What is the difference in the hormones the posterior and anterior pit. releases?
anterior - a variety of hormones to control wide variety of functions
posterior - stores and releases 2 hormones
What is the hypothalamic-hypophyseal tract?
since the neurohypophysis is made up of nervous tissue, it contains axons and axon terminals. these neurons run from the post. pit. and have their cell bodies in the nuclei of the hypothalamus
What is the difference in the composition of the anterior and posterior pit gland?
anterior - epithelial tissue
posterior - nervous tissue
What is the hypophyseal portal system?
blood flow from the hypothalamus to the anterior pituitary
- blood contains hormones from hypothalamus
What is the blood flow in the hypophyseal portal system?
superior hypophyseal arteries –> primary plexus of the hypophyseal portal system –> hypophyseal portal veins –> secondary plexus of the hypophyseal portal system –> hypophyseal veins
What are neurosecretory cells?
specialized neurons that synthesize hypothalamic releasing and inhibiting hormones
What are the anterior pit. hormones that act on other endocrine glands?
tropic hormones/tropins
What are the 2 ways to control secretion of anterior pit hormones?
- neurosecretory cells
- negative feedback loops
What kind of hormones do neurosecretory cells in the hypothalamus secrete?
5 releasing and 2 inhibiting
What is the flow of the posterior pituitary blood supply?
internal carotid –> inferior hypophyseal arteries –> capillary plexus of the infundibular process –> posterior hypophyseal veins
Where is the secreted hormones from the hypothalamohypophyseal tract received?
capillary plexus of the infundibular process
What is the role of the posterior hypophyseal veins?
to receive blood from the plexus and to distribute it to target cells in other tissues
What are the functions of hGH?
- stimulate production of IGFs from various body cells (muscles, liver, bone) – cell growth and abundance + increase protein synthesis
- metabolic effects like increase lipolysis (use of fat > glucose for energy)
- breakdown of glycogen into glucose in liver
- decreases glucose uptake into cells (glucose sparing effect)
What is the negative feedback loop of TSH?
low blood levels of T3 + T4/low metabolic rate –> release of TRH (hypothalamus) –> release of TSH (anterior pit.) –> TSH stimulate thyroid follicular cells –> T3 + T4 released into blood –> elevated T3 inhibits release of TRH/TSH
What is the feedback of the anti-diuretic hormone (ADH)?
high blood osmotic pressure –> osmoreceptors (hypothalamus) –> activates neurosecretory cells that synthesize and release ADH –> nerve impulses free ADH from axon terminals in post. pit. to bloodstream –> kidneys will retain water, decrease sweating and arterioles constrict to increase BP
Which gland is the one that is shaped like a butterfly?
thyroid
the thyroid is _____ to the larynx and _____ to the trachea
inferior the larynx, anterior to trachea
how are the right and left lateral lobes of the thyroid gland connected? where are these lobes located?
isthmus
on either side of the trachea
All thyroids have a 3rd lobe. T/F
False. only 50% of them do.
What is the 3rd lobe only found in some thyroids called?
pyramidal lobe
Since the thyroid is very vascular, approximately how much blood does it receive?
80-120 ml/min
What are the 4 arteries that supply the thyroid with blood?
2 SUPERIOR thyroid arteries branching from the EXTERNAL CAROTID
2 INFERIOR thyroid arteries branching from the SUBCLAVIAN ARTERY
What are the 6 veins that blood leaves the thyroid by?
2 SUPERIOR and 2 MIDDLE thyroid veins – INTERNAL JUGULAR
2 INFERIOR thyroid veins – brachiocephalic vein
What are follicles?
Sacs that make up most of the thyroid
What are the walls of the sacs made of?
follicular cells and basement membrane
& parafollicular cells
what is the lumen in the sacs?
the “void”
the cells found in the sacs change shape based on the presence and absence of TSH. T/F
true.
squamous when inactive, columnar when active
What are the two hormones that the follicular cells produce?
T3 - triiodothyronine
T4 - tetraodothyronine (thyroxine)
What are the parafollicular cells secrete?
calcitonin
the thyroid gland stores _________ worth of hormone.
approx. 100 days
What is the key chemical element for thyroid hormone formation and where do we get it?
iodide/iodine
(google says… seaweed, fish, some dairy products)…
what is the most common mechanism of transportation for thyroid hormones?
thyroxine-binding globulin (TBG)
what are other mechanisms of transportation for thyroid hormones?
T3 0.3%
T4 0.03%
Hypothyroidism = ?
Hyperthyroidism = ?
Euthyroid = ?
hypo - below normal function
hyper - above normal function
euthyroid - normal thyroid gland function
What is goiter?
the enlargement of the thyroid gland
Cause of goiter is only hyperthyroidism. T/F
false.
it could be hyper, hypo or euthyroid
What are two things that are associated with hyperthyroidism?
- Grave’s disease
- toxic nodule
What is grave’s disease?
it is an autoimmune disorder where the body produces antibodies that mimic tsh. which results in the thyroid making more hormone and follicular cells to grow
what are some symptoms of grave’s disease?
- enlarged thyroid
- edema behind eyes
- increase heart rate, body temp, bp
- hyperactivity
- thin
what is a singular nodule called? what about multiple nodules?
singular = toxic adenoma
multiple = multi nodular toxic goiter or Plummer’s disease
What are some examples of hypothyroidism?
- myxedema
- congenital hypothyroidism
What is myxedema?
adult onset of hypothyroidism
- swelling due to excessive interstitial fluid
- low hr, body temp
- dry hair, skin
- weakness and lethargy/less alert
- easily gain weight
What is congenital hypothyroidism?
when you’re born with the a low fxning thyroid
- results in severe intellectual disabilities and stunted bone growth
what does calcitonin do?
it inhibits osteoclasts therefore decreases blood Ca2+ level
where are the parathyroid glands found?
embedded on the posterior surface of each thyroid lobe; one superior and one inferior
it is made up of two kinds of epithelial tissues. what are they?
- chief cells (more numerous)
- oxyphil cells
what is the function of the chief cells? oxyphil cells?
chief - produce PTH
oxyphil - unknown func
PTH secretion is directly controlled by the ________ by ______ feedback loop.
blood calcium level, negative feedback loop
How does PTH regulate Ca2+?
- increases number and activity of osteoclasts (increase resorption)
- decreases Ca2+ in urine (increase kidney resorption)
- promotes kidneys to produce more calcitriol to increase mineral absorption in GI
where do you find the adrenal glands?
- superior to the kidneys
- in the retroperitoneal space
what is the outer region of the adrenal gland called? inner region?
outer = adrenal CORTEX
inner = adrenal MEDULLA
What are the three zones that make up the adrenal cortex?
- zona glomerulosa
- zona fasciculata
- zona reticularis
what does the zona glomerulosa secrete? what does that hormone do?
it secretes aldosterone
it regulates minerals (Na+ and K+); mineral homeostasis
what does the zona fasciculata secrete? what does that hormone do?
secretes glucocorticoids – cortisol
it regulates glucose homeostasis
what does the zona reticularis secrete? what does that hormone do?
secretes androgens
– masculinizing effect
what does aldosterone do?
it controls Na+ and K+ minerals, which helps adjust blood pressure and blood volume
- excretion of H+ in urine to maintain internal pH (~7.35)
what is the pathway that control aldosterone secretion?
renin-angiotensin-aldosterone pathway
what is the primary glucocorticoid in the body?
cortisol
what does cortisol do?
- increase protein breakdown to free AA for protein synthesis/atp production
- liver cells convert aa or lactic acid to glucose –> atp production (gluconeogenesis)
- stimulate lipolysis
- stress resistance (raising BP and increasing levels of ATP)
- anti-inflammatory effect (inhibits WBC in inflammation response)
- depress immune response
what is unique about the adrenal medulla?
it is composed of modified sympathetic ganglions of the ANS
*key is that these cells lack axons, form clusters around large blood vessels and doesn’t secrete neurotransmitters but hormones
what do chromatin cells produce? and where?
catecholamines within the adrenal medulla
what hormones does the chromatin cells in the adrenal medulla secrete?
epinephrine (80%) and norepinephrine (20%)
what are epinephrine and norepinephrine also known as?
E = adrenaline
NE = noradenaline
what do the catecholamines do?
- increase HR and force contraction
- increase cardiac output–BP
- increase blood flow to the heart, skeletal muscle, liver, and adipose
- dilate airways
- increase serum [FA] and serum [glucose]
the pancreas has both endocrine and exocrine functions. T/F (what is the difference?)
true.
endocrine - release into bloodstream
exocrine - into ducts
the pancreas is a flatten organ with just a head and tail. t/f
false.
flattened organ with a head (in the curve of the intestine), body and tail
where do you find the pancreas?
in the curve of the duodenum
what is the pancreas responsible for?
the regulation of glucagon and insulin
what are the clusters of exocrine cells called?
acini
what are the clusters of endocrine tissues called? and where are they found?
pancreatic islets (islets of langerhans)
found scattered among acini
what do alpha cells secrete?
glucagon
what do beta cells secrete?
insulin
what do delta cells secrete?
somatostatin
what do f cells secrete?
pancreatic polypeptides
Eustress vs. distress?
eustress - normal stimulation
distress - harmful stimulation
what are the three-phase stress response?
- initial fight or flight
- resistance reaction
- exhaustion
