Adrenal Gland Flashcards
Where are the adrenal glands, how big are they, and what do they look like on a scan?
What is the orientation of this image? (i.e. which is the left adrenal gland, and which is the right one?
Just above the kidneys - 3-4 cm in size, look like triangles on CT scans
Fill in the labels on this diagram of the blood supply to the adrenal gland:
The inferior vena cava (IVC) comes up from the legs, and travels up to the heart
Right adrenal gland has many arteries (57 according to Grey’s Anatomy), but only one vein, which drains into the IVC - important to note during surgeries, as all the arteries need to be clipped
Left adrenal gland also has many arteries supplying it blood, but one vein that drains into the renal vein, and the renal vein drains into the IVC
All the arteries supplying the adrenal glands enter from the outside, but their veins emerge from the inside (medulla portion)
What is the advantage of the right adrenal gland having only one vein that drains into the IVC directly?
Why is it harder to cannulate the vein of the left adrenal gland?
Allows for clinicians to measure hormone secretions accurately, by cannulating that one vein
It’s vein drains into the renal vein, which drains into the IVC, so the cannula needs to turn 2 corners (shown in the diagram)
Draw a diagram showing the position of the adrenal glands and their blood supply system:
What are the 2 parts of the adrenal gland?
What are the names of the different zones of the adrenal cortex and what hormones do they each produce?
What hormone does the adrenal medulla produce?
What type of hormones does the adrenal medulla produce?
Adrenal cortex and medulla
The adrenal cortex is made up of 3 zones:
Zona glomerulosa (outermost zone) - set of enzymes that make the hormone aldosterone
Zona fasciculata (thick one) - makes the hormone cortisol (and some sex steroids)
Zona reticularis - also makes the hormone cortisol (and some sex steroids)
Adrenal medulla (inner most section) - secretes catecholamines i.e. makes adrenaline (and some noradrenaline)
Adrenal cortex (made up of the first 3 zones only, not the adrenal medulla) makes corticosteroids (so aldosterone, cortisol, testosterone and oestrogen)
What are the adrenal hormones? Fill in the table:
Fill in the labels in the diagram showing which zones of the adrenal cortex release which hormone:
In which organisms is the production of sex steroids more important?
More important in animals rather than humans
Fill in the labels of the adrenal cortex under the microscope:
Describe the rest of the image?
How can the zones be seen more clearly?
Thin outer layer = capsule
ZG = aldosterone production
ZF = cortisol production
Medulla = adrenaline production
Using a stain with an Ab that binds ot the specific hormones
How do all the hormones eventually filter into the renal vein?
Fill in the labels on this diagram:
One of many of the suprarenal arteries enter from the outside and pass through the capsule layer
Travel through the glomerulosa picking up the aldosterone, goes into the deeper zones to pick up the cortisol, eventually all the hormones drain into the central vein
The central vein then drains into the IVC
Draw a diagram detailing the different zones of the adrenal cortex and what hormones they produce:
What is the precursor for the production of corticosteroids from the adrenal cortex? What is the structure of it?
What is the length of the carbon chain / backbone in cholestrol i.e. how many carbons?
What is meant by the term steroids and what are different types of steroids and their effects?
Is adrenaline a steroid?
Cholestrol
27 carbons
Steroid = any of the molecules that come from cholestrol (must have cholestrol backbone, note the number of carbons)
Some steroids help build muscle (sex steroid), other steroids are prescribed for autoimmune conditions (cortisol), etc.
No, does not come from cholestrol
Which zones of the adrenal gland follow which pathways in the diagram?
How are the end-products of each of the pathways produced?
The pathways from left to right: first pathway produces aldosterone from the zona glomerulosa, the second and third pathways are cortisol and sex steroids respectively from the zona fasciculata and zona reticularis
Specific enzymes catalyse the synthesis of speciific alterations to the molecules
Mineralocorticoid = controls mineral levels e.g. Na+, K+
Glocucorticoid = controls glucose, and so consequently BP
Describe the pathway for the synthesis of aldosterone from cholestrol:
How many enzymes required from making the precursor to forming aldosterone? How is aldosterone production controlled to control mineral (Na+ / K+) levels?
- Cholestrol’s side chain (C22) is cleaved to form pregnenolone
- 3 beta hydroxy steroid dehydrogenase oxidises the alcohol group in pregnenolone to form a ketone group, producing progesterone
- Hydroxylate (put an OH group on) position 21 using 21 hydroxylase forms the precursor to aldosterone (called 11 deoxycorticosterone)
- Hydroxylate position 11 using 11 hydroxylase (forms corticosterone)
- Hydroxylate position 17 using 17 hydroxylase to finally form aldosterone
3 enzymes - these enzymes can be controlled to regulate aldosterone production to control mineral levels
What is the pathway for the synthesis of cortisol from cholestrol?
- Cholestrol’s side chain (C22) is cleaved to form pregnenolone
- 3 beta hydroxy steroid dehydrogenase oxidises the alcohol group in pregnenolone to form a ketone group, producing progesterone
- Hydroxylate position 17 using 17 hydroxylase (to form 17 hydroxy-progesterone)
- Hydroxylate position 21 using 21 hydroxylase (to form 11 deoxy-cortisol)
- Hydroxylate position 11 using 11 hydroxylase to finally form cortisol
What is the pathway for the synthesis of testosterone from cholestrol? (covered in the gonad lecture)
What is the difference between testosterone production and oestrogen production?
This is covered in the gonads lecture
V. small change between testosterone and oestrogren - therefore small errors in the pathways can have huge implications
Fill in the missing labels in this diagram, summarising the 3 pathways to produce aldosterone, cortisol and testosterone from cholestrol:
What is aldosterone important in controlling?
Where does aldosterone act?
Blood pressure is driven by which ion?
What is aldosterone’s mechanism of action?
What’s lost in the presence of aldosterone?
Blood pressure control
Aldosterone promotes Na+ and H2O reabsorption in the DCT to increase BP (also acts on sweat glands, and colon)
BP is dependent on Na+, and Na+ concentration in the blood (as it affects osmosis of water in / out of cells)
When BP falls, aldosterone production increases, and it travels via the bloodstream to the DCT cells. It is lipid soluble, it enters the cell and turns on genes that synthesise Na+ channels. Na+ channels attach on the lumen side of the DCT cell, and Na+/K+ pumps attach on the blood side of the DCT cell, which uses ATP to pump Na+ into the bloodstream from the urine - increases amount of Na+ being taken back into the blood, so water reabsorption also consequently increases (due to osmotic forces)
K+ and H+ lost
Where are the 2 sets of negative feedback loops produced by cortisol?
When cortisol levels go up, it suppresses ACTH (adrenocorticotrohpin hormone) production, and the precursor of ACTH, CRH (corticotrophin hormone)
Draw a simplistic diagram detailing the HPA axis?
HPA = Hypothalamo Pituitary Adrenal
Fill in the missing labels of the HPA axis drawing:
CRH - stands for corticotrophin
ACTH - is also called corticotrophin
CRH comes down to the pituitary gland and causes the pituitary galnd to form ACTH
ACTH acts on the adrenal gland, so the adrenal cortex produces cortisol
There are 2 negative feedback loops of cortisol - one to the pituitary (ACTH production) and one to the hypothalamus (CRH production)
What is the circadian pattern of cortisol production in the average human?
Why is it important to note the pattern of cortisol production?
Diurnal: Low during midnight, starts rising at about 5am, peaks when person wakes (8:30am ish), then gradually lowers throughout the day
Medications can be set to match the circadian rhythm, e.g. if a person needs to take cortisol supplements, it would be best to take them in the morning
What is Addison’s disease and what is it caused by?
What did patterns in patients did Thomas Addison notice in the 18th century?
How do the symptoms present clinically?
Primary renal failure (adreno-cortical failure) - caused by either an autoimmune condition which destroys the adrenal cortex or tuberculosis (TB), which kills the cells of the adrenal gland
When the adrenal gland failed to produce cortisol and aldosterone, BGL (blood glucose levels) fell, hyperpigmentation (even in places where the sun does not hit, e.g. gums), hypoglycaemic, vomiting, dehydration, eventually death, vitiligo, and in the post mortums: atrophy or TB in the adrenal gland
Lack of aldosterone = responsible for weight loss, low BP, low salt levels; Lack of cortisol = hypoglycaemia (as cortisol liberates glucose for energy, esp. in stressful situations); Increased POMC / MSH produciton = hyperpigmentation; vitiligo (if you have one autoimmune condition, you’re likely to have another)
What major precursor molecule does the adrenal gland make, so when it breaks down, it releases a molecule that causes the tanning?
What is the action of this precursor?
So why or how does this precursor resulting in hyperpigmentation in patients?
POMC (proopiomelanocortin)
This large precursor that is broken down to produce ACTH and MSH (melanocyte stimulating hormone)
When a patient has adrenal failure, the negative feedback loop causes the production of more ACTH. Therefore, more POMC molecules need to be broken down for ACTH production, so more MSH is also made as the side product
What is Cushing syndrome?
What are some causes of Cushing syndrome?
What are the symptoms of Cushing syndrome?
Too much production of cortisol
- Steroids by mouth; 2. pituitary adenoma = tumour - causes excess ACTH production 3. Ectopic (in the wrong place) ACTH - e.g. lung cancer tumours producing ACTH though its not suppose to 4. Adrenal adenoma / carcinoma - excess cortisol production
Symptoms = weight gain (change in metabolism), depression, retain fat and lose protein, thin skin, muscle weaknesses, poor protein synthesis (poor wound healing, stretchmarks etc), depression (cortisol affects the brain), diabetic, high BP, moon face, difficulty climbing stairs (very thin legs but put on weight), steroid suppress immune system
What type of hormones does the adrenal medulla produce?
What is the precursor for these hormones?
What is the pathway for the production of these hormones from its precurson?
Catechloamines e.g. adrenaline, noradrenal etc.
An amino acid called tyrosine
Tyrosine is hydroxylated to dopamine in the medulla, then the dopamine is activated by further oxidation to produce noradrenaline (NA) or with an extra added methyl group, adrenaline (A)
