Adrenal Gland Flashcards
Where are the adrenal glands?
Just above the kidney
What is the size and appearence of the adrenal glands?
4-5cm look like triangles(represented this way in diagrams)
When you draw the adrenal glands what must you consider?
Think about it fro the patient perspective as when they are facing you there right adrenal gland is on your left and there left adrenal gland is on your right-remember this when you draw them
How many arteries and veins does the right adrenal gland have?
57 arteries and 1 vein -right adrenal vein which drains into the Inferior vena cava
How can you measure the hormone concentration in the right adrenal gland ?
By canulating the inferior vena cava amd putting a line in going into the adrenal vein as this is the only vein from which the hormones exit
How many veins in the left adrenal gland and what major vein does it drain into?
1 which drains into the left renal vein
How do you measure hormone levels in the left adrenal gland?
Put central line into the inferior vena cava, hook round two corners, get in there and then take blood from the adrenal vein Harder than with the right
Draw diagram of the left and right adrenal gland and the veins
In notes
What are the zones of the adrenal gland and waht do they make?
Adrenal cortex-made up of 3 zones all which make CORTICOSTEROIDS:
-Zona Glomerulosa(very thin) - Aldesterone
-Zona fasciculata(thick)-cortisol
-Zona reticularis(not very important in humans- can make some oestrogen and androgen-mainly in animals)
In the centre of the zones is ADRENAL MEDULLA-makes CATECHOLAMINES:
-80% Adrenaline(epinephrine) which are responsible for fight or flight and increased heart rate
-20% noradrenaline (norepinephrine)
(small amount of dopamine)
How do hormones from the adrenal gland enter the IVC?
The arteries around the adrenal gland go through it and as they pass through each zone they pick up hormones and then these arteries connect to the vein so the hormones enter the vein
Draw the zones of the adrenal gland?
In notes
What is the precursor of corticosteroids?
Give 3 exmples of corticosteroids?
Cholesterol - has 27 carbons
Mineral corticosteroids(aldosterone)
Glucocorticoids(cortisol)
sex steroids(androgens and eostrogens)
What is a steroid?
Anything that comes from a Cholesterol
Describe the synthesis of aldesterone?
1-start with cholesterol
2-side chain at carbon 22 is cleaved off to make PREGNENOLINE
3-Oxidise OH group at carbon 3 using enzyme 3 BETA HYDROXY STEROID DEHYDROGENASE to form PROGESTERONE
4- Add OH group to position 21 using 21 HYDROYLASE to form 11 DEOXYCORTICOSTERONE
5-Then add OH group to position 11 using 11 HYDROXYLASE to give CORTICOSTERONE
6-Then add OH group at positIon 18 using 18 HYDROXYLASEto give ALDOSTERONE
Describe the synthesis of Cortisol?
1-start with cholesterol
2-side chain at carbon 22 is cleaved off to make PREGNENOLINE
3-Oxidise OH group at carbon 3 using enzyme 3 BETA HYDROXY STEROID DEHYDROGENASE to form PROGESTERONE
4-add OH group at position 17 using 17 HYDROXYLASE to give 17 HYDROXY-PROGESTERONE
5- add OH group at position 21 via 21 HYDROXLASE to give 11 DEOXY-CORTISOL
6-Add OH at position 11 via 11 HYDROXYLASE to give cortisol
What is the function of aldosterone?
Aldosterone-increases SODIUM reabsorpton from urine important for BLOOD PRESSURE CONTROL
1-When there is low Blood pressure and low sodium in the blood more aldesterone is released
2- Aldesterone enters the PERTIBULAR capillaries which surround the distal tubues as well as the loop of henle
3-Aldosterone diffuses into the principle renal epithelium cells
4- In the cytoplasm of the cell it binds with receptors to form a COMPLEX
5-the complex then diffuses into the NUCLEUS of the cell where it upregulates the transcription of proteins for sodium transport and sodium potassium pumps
6-Sodium can move from the urine into the cell via the transporter. Then move from the cell into the capillaries via the sodium potassium transporter using ATP (water follows the salt via osmosis so more water reabsorption occurs)
7- Potassium and H+ then enters urine as waste
8- Blood pressure is raised
Overall stimulates Na+reabsorption in the distal convoluted tubule and cortical collecting duct in kidney(and sweat glands, gastric glands,colon)
Describe briefly the synthesis of sex steroid?
Cholesterol->Progesterone->17 hydroxyprogesterone->sex steroids->testosterone->oestrogen
How is aldesterone regulated?
1- Low blood pressure (renal perfussion pressure) detected by the JUXTAGLOMERULAR APPARATUS (JGA)cells of the kidney causes MORE RENIN to be made because more adrenaline is made to increase renal sympathetic activity = more renin
3- The MASCULA DENSA cells in the distal convoluted tubule detects sodium concentration so also signals the JGA cells to make more or less renin
4-Renin is an enzyme that converts the another enzyme called ANGIOTENSIN to ANGIOTENSIN 1
5-This is then converted in to ANGIOTENSIN II by ACE(angiotensin converting enzyme)
6- THis stimulates the adrenal gland to make aldesterone and also has other effects such as vasoconstriciton
What are the effects of cortisol?
Released when you are stressed - gets you ready for flight or fight so increased glucose availibility
Metabolic effects:
- Peripheral protein catabolism
- hepatic gluconeogenesis
- increased blood glucose conc
- fat metabolism
- enhanced effects of glucagon and catecholamines
Renal and Cardivascular effects:
- excretion of water load
- Increased vascular permeability
How is cortisol secretion regulated?
1-CRH is secreted from the hyperthalamus when your stressed
2-This results in ACTH being released from the pituitary gland which increases cortisol levels
3-When cortisol levels raise it has a negative feedback response as it tells the pituitary glands to stop making ACTH and tells the Hyperthalamus to stop secreting CRH
(HPA Axis)
Draw the hypothalamus Pituitary Axis (HPA axis)?
In notes
What would you expect to see when measuring cortisol levels in healthy volunteers?
Cortisol levels increase at about 5 am and peaks at about 8:30 am.
Then the levels decrease in a pulsating manner due to stress during the day making it rise
At midnight the levels are at its lowest
The change in cortisol depending on the time of day is called the CIRCADIAN rhythm
What is the commonest cause of primary adrenal failure in the Uk also known as Addisons disease?
Autoimmune disease where the body does not recognise the adrenal tissues as self so destroys the adrenal cortex therefore glands cant produce enough steroid hormones
What is the commonest cause of adrenal failure worldwide?
TB of the adrenal glands as TB eats up the cells in the gland
What are the symptoms of Addisons disease?
-Low blood pressure (as adrenal glands don’t produce sufficent steroid hormones like aldesterone)
- Weakness
- weight loss
- Hyperpigmentation of the skin(darker -Vitiligo(autoimmune)
Gastrointestinal: -Nausea -Diarrhea -Vomiting -Constipation -Abdominal pain
Adrenal Crisis: -Fever -Syncope -Convulsions -Hypoglycemia -Hyponatremia -Severe vomiting and diarrhea
if not treated results in death
-Atrophy of the adrenal gland(autoimmune)
Why do patients with Addisons have a good tan
The pituitary gland makes a large precursor molecule called Pro-opio-melanocortin(POMC)
This is cleaved to forms small peptides including ACTH, MSH and endorphins
When you have adrenal failure you make more ACTH (to increase cortisol release from adrenal glands) and therefore more MSH (melanosite stimulating hormone) as they both come form the breakdown of the same precursor
More MSH results in more melanin =tan
Give a summary of Addisons disease?
- Cortisol defficinecy
- Aldesterone defficinecy
- Salt loss
- Low Blood pressure
- Eventual death without treatment
What is the urgent treatment of someone with Addison’s crisis(adrenal crisis)?
Patient taken to intensive care
- given SALINE to replace salt
- Given DEXTROSE to prevent hypoglycaemia which could be due to glucocoticoid(cortisol) defiency -Give hydrocorisone or another glucocorticoid
What is cushings syndrome?
-too much cortisol either due to a tumour in the adrenal or pituitary
What are the symptoms of cushing’s syndorme?
- Metabolism changes and you start putting on weight
- Moon face
- Thin skin because you lose protein which results in easy bruising
- putting on weight =bigger abdomen and because you cant make proteins the skin tears as it stretches resulting in red stretch marks
- Red cheeks
- Mental changes(depression)
- Fat pads on shoulders
- Impaired glucose tolerence(diabetes )
-High blood pressure
- Poor wound healing
- Proximal myopathy(muscle weakness )
- Thin arms and legs
What are the 4 causes of cushing’s disease?
- Taking steroids by mouth(too much)
- Pituitary dependent cushings disease(pituitary adenoma)
- Ectopic ACTH (lung cancer)- where ACTH is being made where it shouldn’t
- Adrenal adenoma or carcinoma(cancer) that makes cortisol
What is the precursor for catecholamines?
Amino acid called tyrosine
How is Adrenaline and noradrenaline made
Tyrosine hydroxylated to DOPA and this is decarboxylated to Dopamine
- Dopamine is hydroxylated to Noradrenaline
- Noradrenaline had a methyl group added to it to produce Adrenaline
Where are catecholamines stored and when are they released?
-stored in the CYTOPLASMIC GRANULES in the adrenal gland -released in response to ACh from the preganglionic sympathetic neurones
How is adrenaline removed from the blood ?
Degraded by 2 hepatic enzymes:
Monoamine oxidase and catechol-o-methyl transferase
