Stress hormones Flashcards
Which part of the pituitary gland is neuronal
posterior
Which part of the pituitary gland is endocrine
anterior
What is the function of Releasing Hormone, and what part of the pituitary does it regulate?
it stimulates hormone release in anterior pituitary
What is the five hypothalamus-pituitary hormonal axes?
These are 5 Releasing hormones (TRH, CRH, GnRH, GRGH, PRLH) which stimulate the release of other hormones in the anterior pituitary thats targets certain endocrine tissue to release hormones
To what axis does the thyrotrophin releasing hormone (TRH) refer to?
thyroid (HPT-axis)
To what axis does the gonadotrophin releasing hormone (GnRH) refer to?
gonads (HPG-axis)
Why is the growth hormone releasing hormone different from the other RH’s?
This hormone releases the growth hormone which can immediately be consumed by the body, in stead of needing to stimulate more tissue for hormonal release that can be consumed. So GHRH has 2 steps in stead of 3 steps
What are the functions of growth hormone in most tissues?
- Inhibition of glucose uptake and utilization
- Increased amino acid uptake and protein synthesis
What are the functions of growth hormone in fat cells?
Fatty acid mobilization for primary energy source
Which organs mobilize fatty acids?
Liver: ketone body synthesis –> also energy for brain
Muscle: energt substrate
What 2 things mediate the GRH negative feedback, so inhibit GH release?
- somatomedins (GH-IH): secondary hormones
- glucose: blood metabolites
what does increased protein synthesis rates stimulate?
cell growth and cell division
What causes gigantism?
Excessive GH release due to anterior pituitary tumor
What causes pituitary dwarfism?
GH deficiency –> body ratio is still normal
Why is injecting GH (or testosteron too) at an older age dangerous?
At an older age you are more likely to get mutations, so you don’t want to stimulate cell growth, this will induce tumors. This is also why you synthesise less GH and testosterone at an older age!
What is the cascade of corticotrophin releasing hormone
ACTH –> endocrine organ: adrenal cortex –> secretion glucocorticoids (cortisol)
What is the primary function of cortisol?
Convert long-term energy substrates into readily available substrates like glucose
–> breaks down amino acids, fatty acids for more glucose
At what part of the day is CRH release the highest?
Morning, because this is when your body is craving for extra glucose
At what part of the day is GRH release the highest?
Night, because GH helps your body restore while you sleep
What mediates the CRH negative feedback and which 3 organs does it affect?
Cortisol in adrenal cortex
1. anterior pituitary gland
2. hypothalamus
3. hippocampus
Which 2 steroids does the adrenal release
- glucocorticoids –> cortisol
- mineralocortiocoid –> aldosterone
What is stress, what what is the result?
any condition that threatens homeostasis
- specific, generalized or psychological stress response
What is the alarm phase
fight or flight –> immediate short-term response
1. activation sympathetic nervous system
2. activation adrenal medulla –> adrenaline
What 3 phases are there in the generalized stress response
- alarm phase 2. resistance phase 3. exhaustion phase
What is the resistance phase
a long-term metabolic adjustem
1. ACTH –> cortisol
2. Glucagon release pancreas
3. Growth hormone
4. AHD (vasopressin)
What is the exhaustion phase
A collapse of vital systems, you can die from this response
What is Addisons disease (AD) and what is the result of AD
insufficiency in cortisol (primary) or ACTH (secondary) which causes inability to tolerate stress or mobilize energy reserves–> fatique and weakness
What is Cushings disease (CD)
Overproduction of cortisol that results in excessive breakdown of lipids and proteins –> obesity
What is Cushings disease (CD)
Overproduction of cortisol that results in excessive breakdown of lipids and proteins –> obesity
What is the axis of thyrothropin releasing hormone (THR)?
Thyroid (HPT-axis)
What is the primary function of thyroid hormone?
increasing oxygen consumption and metabolic heat production
At what part of the day is TRH the highest?
Night
which organs does the thyroid hormone target?
muscle, heart, liver and kidney
How is thyroid hormone structured?
tyrosin + iodine
T4 = iodine on 4 locations
T3= iodine on 3 locations (most active)
With what does the thyroid receptor form a dimer and when does transcription get activated?
Retinoic acid receptors (RXR), upond binding of T3. The receptor is already bound even when T3 is absent (this is also why it can act faster than other steroids due to this “pre-assembly”), but it only gets activated when T3 is present
What is myxedema, can it be treated?
Hypothyroidism, autoimmune disease –> destruction of own thyroid glands
- low metabolic rate and body temperature
- muscle weakness and fatigue
- depression
Yes, with levothyroxine
What is Graves disease
Hyperthyroidism, autoimmune disease –> overactivity thyroid glands
- high metabolic rate and body temperature
- weightloss and restlessness
- protruding eyes and enlarged thyroid (goiter)
How does radioactive iodine help graves disease
all iodine immediately goes to the thyroid glands, so when you make this radioactive, you actually get specific chemotherapy
Why is maternal iodine supplementation important?
to prevent neurological cretinism:
- reduced synapse formation, myelination, axonal transport and mental retardation of the infant
