Endocrine System Flashcards
Glands that secrete substances through openings (ducts) onto your body surfaces
exocrine glands
i.e sweat glands, skin oil glands, earwax glands, breast milk glands
Name at least two examples of endocrine glands that end in “gland”
- pituitary gland
- thyroid gland
- parathyroid glands
Name three endocrine glands that don’t end in “gland”
- Hypothalamus
- adrenal cortex
- medulla
- pancreas
- gonads
Name 2 organs that have both exocrine and endocrine functions
- Pancreas (releases digestive enzymes via ducts & hormones i.e insulin and glucagon)
- Liver (releases bile via ducts & secretes angiotensin hormone)
When a cell secretes a signaling moleculethat acts on a nearby cell
paracrine signaling
heavily invlved in differentiation in embryonic development
para = next to
when a cell releases a molecule that acts on itself
autocrine signaling
auto = Self
Signaling that requires cells to be in close contact with each other
juxtacrine signaling
juxta - think just next to
A cell that releases secretions via exocytosis
merocrine cells
Cells that release secretions via membrane-bound vesicles
apocrine cell
Results from rupture of the plasma membrae, destroying the cell and relesing its product from the cytoplasm into the lumen
i.e sebaceous glands of the skin
holocrine secretion
Hormones can be classified according to their chemical structure as ____ hormones, ____ hormones, or ____ derivatives
Peptide hormones, steroid hormones, or amino acid derivatices
True or False
Peptide hormones can diffuse freely in the blood, but cannot cross the lipid bilayer membrane of their target cells
True
due to their hydrophillic nature
Thus, they have to exert their effects via receptors embedded on the plasma membrane surfce
Peptide or Steroid Hormone?
Which type of hormone is associated with signal cascades, amplificiaction, and rapid, intense, short-term impacts on cellular functions?
Peptide hormones
due to second messenger systems (i.e cAMP) resulting in signal cascades
The image below describes what process?
Second-messenger systems
in peptide hormones
Steroid or Peptide hormones?
Which hormone category requires transport proteins to reach their targets?
Steroid hormones
their hydrophobic nature prevents them from being soluble in bloodstream
Albumin and sex-hormone binding globulin are examples of …
transport proteins
Peptide or Steroid?
____ hormones can diffuse directly through the lipid bilayer membrane and enter their target cells
Steroid hormones
due to their hydrophobicity and small size
Peptide or Steroid hormone?
Works by modulating gene transcription
receptor-hormone complex binds directly to DNA to affect transcription
Steroid hormones
associated with a slower-onset and longer-lasting physiological response
Name at least 4 steroid hormones
- Estradiol
- Testosterone
- Aldosterone
- Cortisol
Note: steroid hormones have 4-ring structure!!!
peptide or steroid
____ are first translated as preprohormones, then (in the rough ER) modified into prohormones. Prohormones are processed in the Golgi apparatus, then are cleaved by endo____ases and may be modified by the addition of carbohydrates to generate the final, active form of the hormone. The hormones are then packaged into vescicels to be releasex via exocytosis
Peptide hormones
Peptide or Steroid?
Synthezides from cholesterol in the smooth ER and *diffuse directly through the cell membrane *
Steroid
Peptide or Steroid (function)
Regulation of other hormones
Peptide
+ short term responses
Peptide or Steroid (function)
Sex, sugar, and salt
The 3 S’s!
Steroid
salt = mineralocorticoids
sugar = glucocorticoids
steroid hormoes affects the 3 S’s
Which amino acid derived hormones are lipid soluble and behave much like steroid hormones?
T3 and T4
Which amino acid derived hormones are water-soluble and act similar to peptide hormones, exerting powerful, short term responses?
Epinephrine and norephinephrine
True or False
Water-soluble amino acid derived hormones are either water soluble or lipid-soluble
False
Some are both! i.e Melatonin
Name the hormone category
any of a class of hormones from the anterior pituitary gland that affect the secretion of other endocrine glands
Tropic hormones
tropic hormones –> target cells –> other hormones
hormones that directly stimulate target cells to induce effects
nontropic hormones
nontropc hormones –> target cells –> physiological effects
the hypothalamus-anterior pituitary-adrenal cortex (HPA) axis is an example of a ____ loop
Negative feedback loop
What is the tropic hormone that the hypothalamus releases in the HPA axis?
Corticotropin-releasing hormone (CRH)
Which hormone acts on the anterior pituitary gland and stimulates the release of adrenocorticotropic hormone (ACTH)
Corticotropin-releasing hormone (CRH)
This hormone is tropic and acts on the adrenal cortex, causing the release of cortisol
adrenocorticotropic hormone (ACTH)
What is the physiological function of the negative feedback loop of the HPA axis?
The negative feedback exerted by cortisol on CRH and ACTH inhibits further cortisol production, which prevents levels of cortisol from getting out of control and inducing an overly intense long-term stress response
Name one hormone involved in the positive feedback loop of labor?
oxytocin
uterine contactions stimulate the release of more oxytocin, which stimulates stronger contractions, and the process continues to amplify itself until childbirth
Which type of feedback loops have a distinct physiological endpoint?
Positive feedbak loops
without an endpoint, these loops would spiral out of control
the branch of biology (specifically of physiology) which studies the interaction between the nervous system and the endocrine system; i.e. how the brain regulates the hormonal activity in the body.
Neuroendocrinology
In general, when thinking about endocrine regulation or the regulation of any biochemical pathway, you should (probably) be thinking about ____ feedback
Negative
You should hesitate choosing positive feedback on the MCAT! Positive feedback loops are rare.
The two main hormones associated with glucose regulation are
Insulin and glucagon
growth hormone (GH), epinephrine, and cortisol also affect glucose levels
____ is a peptide hormone released by the pancreas in response to high glucose levels
Insulin
function: reduce blood glucose levels by promoting the transport
function: reduce blood glucose levels by promoting the transport of glucose into the cells via insulin receptors
promotes the transport glucose into the cells
insulin receptors
these receptors then activate glucose transporters and increases the transport of glucose into the cell
What can 3 options do cells have with increased glucose uptake?
- use glucose immediately via glycolysis
- storage as glycogen in muscle and liver
- adiptocytes can store downstream byproducts of glucose metabolism as triglycerides
insulin upregualtes all of these proceses, as well as protein synthesis
the technical term for a fat cell
adiptocytes
what hormone reduces the rate of glyconeogenesis, lipolysis, and fatty acid oxidation, and protein breakdown
Insulin
What hormone is released by the pancreas when there are suboptimal levels of glucose?
glucagon
glucose is gone
Which hormone promotes glycogenolysis and gluconeogenesis in liver cells?
glucagon
the biochemical pathway in which glycogen breaks down into glucose-1-phosphate and glucose when blood glucose levels drop
glycogenolysis
the synthesis of glucose from non-carbohydrate sources like lactic acid, glycerol, amino acids and occurs in liver and kidneys.
gluconeogenesis
graphically describe the relationships between blood glucose levels, insulin, and glycogen
which hormone released by the adrenal cortex increases blood glucose levels in response to stress?
Cortisol
which hormone released by the adrenal medulla plays a major role in the fight-or-flight response and increases blood glucose levels
epinephrine
state where adrenal hormones are secreted from
what hormone is released in response to physical stress and growth, but also increases blood glucose levels?
Growth hormone (GH)
List 3+ things
the physiological functions of calcium include:
- Bone density
- NT release
- muscle contractions
- second messenger within the cell
What are the three primary hormones that perform Calcium level maintencance
- parathyroid hormone (PTH)
- calcitonin
- calcitriol
Name the hormone
secreted in response to low blood calcium levels; elevates Ca levels by stimulating increased activity of osteoclasts. Increases calcium absorption from the intestine indirectly by promoting the activation of vitamin D, decreases calcium storage in the bones, and in the kidneys promotes calcium retention
parathyroid hormone (PTH)
cells that break down bone, releasing calcium into the bloodstream
osteoclasts
Name the hormone
released by C cells of thyroid gland and inhibits osteoclast activity; decreases plasma calcium levels by increasing calcium storage in the bones and increasing calcium excretion from the body
calcitonin
cells that help build bone and therefore reduce blood Ca levelsby storing Ca in bone tissue
osteoblasts
plays a crucial role in regulation of serum calcium and phosphate levels
vitamin D
inactive form of vitamin D3, which is processed to form calcitriol and is the biologically active form that affects calcium and phosphate levels
cholecalciferol
form of vitamin D that increases serum calcium levels through the absorption of Ca2+ from the GI tract
calcitriol
How does a lack of fluid manifest physiologically?
think of fluid as blood volume and blood osmolarity
- reduced blood volume (relatively little water is present in the blood plasma)
- reduced BP (consequence of reduced blood volume; less liquid to exert pressure againt walls of blood vessels)
How does a surplus of fluid manifest physiologically?
think of fluid as blood volume and blood osmolarity
- increased blood volume
- increased blood pressure
What two hormones primarily respond to low fluid levels by increasing fluid retention?
- aldosterone
- antidiuretic hormone (ADH)
ADH is also known as….
vasopressin
Vasopressin is also known as….
antidiuretic hormone (ADH)
How does aldosterone increase fluid retention?
- *increasing Na+ *absorption in the distal convoluted tubule and collecting duct of the nephron
- increasing excretion of potassium and hydrogen ions in urine
does not affect osmolarity bc Na+ reabsorption drives H2O absorption
How does ADH increase fluid retention?
increases the permeabilitiy of the collecting duct to water, thereby increasing water absorption
ADH ↓ the osmolarity of blood by ↑ amount of H2O present
ADH is released by the ____ in response to low blood pressure and high plasma osmolarity
posterior pituitary gland
ADH is released by the posterior pituitary gland in response to ____ and ____
- low blood pressure
- high plasma osmolarity
aldosterone is released by the ____ in response to low blood pressure, but is regulated by the renin-angiotensin-aldosterone system
adrenal cortex
aldosterone is regulated by the ____
aldosterone is released in response to …
low blood pressure
in response to low BP, the ____ cells of the kidney release the enzyme renin
juxtaglomerular
aka granular cells; synthesize, store, and secrete the enzyme renin
Renin converts angiotensinogen into ____
angiotensin 1
in the lungs and in blood vessels in the body, angiotensin-converting enzyme converts angiotensin 1 to ____
angiotensin 2
____ is the immediate stimulus of aldosterone release
angiotensin 2
____ restores BP, which in turn inhibits the release of renin (another example of of a negative feedback loop)
aldosterone
hormone used to combat excess blood volume; it’s realeased in response to high blood volume and decreased Na+ reabsorption in the kidney as well as increasing glomerular filration rate (GFR) and inhibiting aldosterone release
atrial natriuretic peptide ANP
____ is the hormone associated with long-term responses to stress
cortisol
cortisol is in what class of hormones?
glucocorticoids
cortisol is released from the ….
adrenal cortex
cortisol’s two main effects are:
- increasing blood glucose levels by stimulating gluconeogenesis and acting as an insulin antagonist, facilitating insulin resistance
- reduces inflammation by inhibiting certain inflammatory immune responses
short term resposes to stress (fight flight or freeze) are assoicated with what two hormones?
Epinephrine and norephinephrine
these two hormones are derived from tyrosine
norephinephrine, epinephrine, and dopamine are neurohormones that fall under which category?
catecholoamines
A type of neurohormone important in stress responses. High levels cause high blood pressure which can lead to headaches, sweating, pounding of the heart, pain in the chest, and anxiety
catecholoamines
a chemical that is made by nerve cells and used to send signals to other cells
neurohormone
epiephrine and norephinephrine are released from the
adrenal medulla
Epinephrine and norephinephrine increase blood glucose levels via what three mechanisms?
- glucogenolysis
- gluconeogenesis
- glucagon release
name 5 physiological stress responses that epinephrine and norepinephrine are responsible for
- increased HR
- respiratory rate
- lipolysis
- vasodilation of blood vessels supplying skeletal muscles
- vasoconstriction of most other blood vessels
norephinephrine is a ____ when it is used to relay signals between neurons in the sympathetic NS, but is a ____ when it is released into the blood to induce systemic affects in other organ systems
neurotransmitter; hormone
what thyroid hormones regulate the metabolic rate?
T3 and T4
what thyroid hormones regulate the metabolic rate?
T3 and T4
T3 and T4 are released in response to which hormone?
thyroid stimulating hormone (TSH)
insufficient levels of thyroid hormones (often caused by iodine sufficiencies) leads to ….
hypothyroidism
steroid hormone released from the testes involved in reprouduction and secondary sex characteristics
testosterone
steroid hormone released from the ovaries involved in reprouduction and secondary sex characteristics
estrogen
stimulated by FSH
steroid hormone that prepares the uterus for implantation and maintaines it througout pregnancy
progesterone
the release of estrogen and testosterone is stimulated by
lutenizing hormone (LH)
____ is a peptide hormne secreted in response to low levels of testosterone and estrogen
LH
lutenizing hormone
LH is released in response to which hormone?
gonadotropin releasing hormone (GnRH)
a surge in which hormone leads to ovulation?
LH
a peptide hormone released in response to GnRH that promotes the growth of ovarian follicles in females, and spermatogenesis in males. Stimulates the ovaries to release estrogen
follicile-stimulating hormone (FSH)
GnRH triggers the anterior pituitary to release what two peptide hormones?
LH and FSH
what hormone maintains te corpus luteum and induces it to secrete progesterone during the first trimester?
human chronic gonadotropin (hCG)
Name. the hormone
Released in response to reduced levels of dopamine tha occur after the placenta is expelled during childbirth. Acts on the mammary glands to enable milk production
prolactin
True or False
TSH is a tropic hormone
True. It stimulates the release of other hormones (T3 and T4) therefore it is a tropic hormone
adrenocorticotropic hormone (ACTH) stimulates the release of which hormones?
cortisol and androgens
note: ACTH is released by the anterior pituitary
True or False
LH is a tropic hormone
True. It stimulates the release of other hormones - estrogen and testosterone
True or False
FSH is not a tropic hormone
False. A tropic hormone is any hormone that that work on other endocrine glands. FSH acts on the ovaries in women, stimulating the maturation of ovarian follicle for the release of an egg during ovulation. In men, it stimulates the testes to produce sperm. It also causes the ovaries to release the hormone, estrogen
GnRH is secreted from the ….
hypothalamus
what hormone is secreted from the hypothalamus and stimulates the release of TSH?
thyrotropin releasing hormone (TRH)
True or False
CRF and CRH are different hormones
False. Corticotropin releasing factor (CRF) is also called corticotropin releasing hormone (CRH)
oxytocin’s two main functions are:
- promotion of uterine contractions leading up to childbirth
- milk ejection resulting from the contraction of smooth muscle tissues in the milk ducts
also promotes social bonding
corticosteroids can be broken down into which three categories?
glucocorticoids (i.e cortisol)
mineralcorticoids (i.e aldosterone)
and cortical sex hormones (i.e testosterone and estrogen)
Name the hormone
slows down the rate of digestie hormone secretion in response to high levels of glucose and amino acids. Also inhibits secretion of insulin and glucagon
somatostatin
hormone important for the development and maturation of T cells
thymosin
Caused by increasingly severe insulin resistance
Type 2 diabetes
Caused by an autoimmune reaction that destroys the beta cells of the pancreas (which secrete insulin)
Type 1 diabetes
