Week 2 - Endocrine system Flashcards
how do hormones travel?
1 Can be dissolved in the blood plasma (water soluble)
2 can travel in the blood bound to plasma proteins
3 Then they diffuse across capillary walls to reach target cells
What is a hormone?
A molecule produced by an endocrine gland that act on target organs.
They regulate physiology and behaviour
What can hormones be classified into?
Proteins
Polypeptides
Lipids
How do hormones work?
The hormone binds to the target cells which has receptors
Where are the hormone binding events?
Ion channels
Receptor binding - GPCR/second messengers
Activation/inhibition of gene expression
What are the different types of cell communication?
Neural - neurotransmitters etc
Endocrine - hormones release into the bloodstream, travel to target tissues and regulate distant organs
Paracrine - the secretions act on and regulate nearby cells
Exocrine - secretions released into body cavity via a duct e.g. saliva into the mouth
Autocrine - the secretions/chemical messenger act on the same cell that produced the secretions
how do hormones travel?
1 Can be dissolved in the blood plasma (water soluble)
2 can travel in the blood bound to plasma proteins
3 Then they diffuse across capillary walls to reach target cells
what is the concentration of a hormone in blood plasma dependent on?
the rate of secretion and the rate of removal
how are hormones removed?
excreted from kidneys
metabolised in blood or target cells
what is antagonism?
where the hormone reduces the number of receptors available for a second hormone
what is permissiveness?
where the hormone increases the number of receptors available for the second hormone
what is the anterior pituitary?
the master gland
controls the functions of other endocrine glands
what are the different cells in the pancreas?
Alpha cells: produce glucagon
Beta cells: produce insulin
Delta cells: somatostatin
Describe the exocrine function of the pancreas?
Secretes digestive enzymes such as lipases, proteases and amylase into the small intestine via the pancreatic duct
Describe the endocrine function of the pancreas?
The pancreas releases hormones via specialised cells to control blood glucose levels
what is glucagon?
produced via alpha cells
Increases blood glucose levels
converts glycogen to glucose
what is insulin?
produced via beta cells
decreases blood glucose levels
coverts glucose to glycogen
describe diabetes mellitus
when you have high blood sugar level (hyperglycaemia)
what are the types of diabetes?
Type 1- where the pancreas fails to produce insulin via beta cells
Type 2- where organs stop responding to insulin
Gestational- comes on during pregnancy
Treatment for type 1 diabetes?
you need to keep blood glucose levels down so you can give insulin injections
‘Artificial Pancreas’- automated insulin delivery
Beta cell transplant
Treatment for type 2 diabetes?
you need to get the cells to respond to insulin again
Lifestyle changes
Metformin medication
Insulin/non insulin therapy
where are the sites in the body where the drugs for type 2 diabetes act?
skeletal muscle
liver
brain
pancreas
small intestine
adipose tissue
what is the HbA1c test?
used to monitor blood glucose levels
symptoms of hyperglycaemia (high blood sugar)
frequent hunger/thirst, fatigue, dry mouth, increased volume of urination
what are microvascular and macrovascular complications of diabetes?
Microvascular:
retinopathy
Nephropathy
neuropathy
Macrovascular:
heart disease
cerebrovascular disease
peripheral artery disease
what is diabetic retinopathy?
a complication that you get from diabetes
it’s where the blood vessels in the retina increase in size, bulge and eventually burst causing a haemorrhage
what is diabetic nephropathy?
a complication that you get from diabetes that causes damage to the kidney where the blood vessel bursts so proteins enter into the urine
why is hypertension (high blood pressure) dangerous when you have diabetes
because it worsens complications and increases risk of heart attack and stroke
how to control blood pressure when you have diabetes?
lifestyle changes
treatment with ACE inhibitor and Angiotensin 2 receptor blocker
what is considered as high blood pressure?
systollic over 130 mmHg
diastolic over 80 mmHg
on 2 different days
what is dyslipidaemia?
imbalance of lipids
how do you manage lipids in diabetes
via an annual screening for diabetic patients via blood tests
what are statins? (DRUGS)
they lower lipids by inhibiting hmg-coa to reduce cholesterol in the liver
what is the hypothalamic pituitary adrenal axis?
the interaction between the hypothalamus, the adrenal glands and the pituitary gland
It responds to stress and results in the production of cortisol, nor/adrenaline
what is the adrenocorticotrophic hormone (ACTH)
the hormone that responds to stress
secreted from anterior pituitary
acts on adrenal glands causing them to release cortisol
Produced from the POMC gene
what are POMC products?
the products that are produced from the POMC gene
Enzymes cleave the POMC gene into smaller products/peptides
some examples of POMC products/peptides
Alpha-MSH - it effects and alters skin pigmentation via GPCRs
Beta-endorphin - has pain relief effects via opioid receptors
what are the diseases related to adrenocorticotrophic hormone (ACTH)
Cushing’s syndrome
Addison’s Syndrome
Secondary Adrenal Insufficiency
what is Cushing’s syndrome?
excess cortisol production by excess ACTH release
REMEMBER THAT ATCH RESULTS IN THE PRODUCTION OF CORTISOL FROM THE ADRENAL GLANDS
what is Addison’s syndrome?
also known as PRIMARY adrenal insufficiency
it’s the lack of ATCH secretion
REMEMBER THAT ATCH RESULTS IN THE PRODUCTION OF CORTISOL FROM THE ADRENAL GLANDS
What is secondary adrenal insufficiency
when the pituitary gland doesn’t produce enough ATCH
what are the different tests to diagnose ATCH diseases
measure your cortisol levels from 9am to midnight
Synacthen tests - to diagnose Addisons disease - this is where you are injected with a synthetic ACTH to measure the amount of cortisol produced
Dexamethasone Suppression test (DMT) - to diagnose Cushing’s syndrome - this is a steroid that carries out negative feedback to the pituitary gland to suppress the secretion of ATCH
What is the difference between Cushings syndrome and Cushings disease?
Cushings syndrome refers to general excessive levels of cortisol
Cushings Disease refers to excessive levels of cortisol caused by a pituitary tumour secreting ACTH
Symptoms of Cushing’s syndrome?
hypertension
purple striae
excessive bruising
hirsutism
truncal obesity
back pain
what are the causes of Cushing’s syndrome?
Normal: excess cortisol made by excess ACTH production (NEGATIVE FEEDBACK LOOP)
Cushing’s Disease:
Adrenal Tumours:
Ectopic ACTH secretion:
Describe the negative feedback loop for ACTH and cortisol?
When there is an excess amount of ACTH, there is an excess production of cortisol, so the negative feedback loop tries to counteract this by getting the levels back to normal
How do you diagnose Cushing’s disease?
MRI
Cortisol saliva test
Checking blood ACTH levels
How to treat Cushing’s disease?
Surgery to remove pituitary tumour
Medication to inhibit the adrenal glands from producing cortisol
Radiation therapy to control pituitary tumour growth
What are the regions of the adrenal glands?
Adrenal cortex
Adrenal medulla
What are the zones of the adrenal glands?
Zona glomerulosa
Zona reticularis
Zona Fasciculata
What are the adrenal sex steroids?
Testosterone (androgen)
Oestrogen
What are glucocorticoids?
A type of steroid hormone.
They contribute to the breaking of glycogen and the forming of glucose.
They stop the secretion of ACTH (negative feedback loop)
an example is cortisol
What are mineralocorticoids?
They are a steroid hormone.
They promote reabsorption of Sodium in the kidneys and promote excretion of potassium.
Promotes electrolyte balance of sodium and potassium across cell membranes throughout the body
an example is aldosterone, which is secreted from the adrenal glands
What is Addison’s disease?
Adrenal hyPOfunction (the adrenal glands can’t function properly)
The adrenal glands produce low levels of cortisol
Common causes of Addison’s disease?
Autoimmune adrenalitis
Tuberculosis
Adrenalectomy
Common features of Addison’s disease?
Weight loss
nausea
lethargy
pigmentation
How do you diagnose Addison’s disease?
Check for hyperpigmentation
Blood tests to check ATCH and cortisol levels
synacthen test
How can you treat Addison’s disease?
Corticosteroid supplement
Mineralocorticoid replacement
What is Conn’s syndrome?
Where the adrenal glands produce excess aldosterone
Where is the thyroid gland?
located below the larynx
above the thyroid cartilage
What does the thyroid gland do?
Produces thyroxine -T4
Produces tri-iodothyronine - T3, which are crucial for metabolic control
Produces calcitonin - decreases calcium levels in the blood by inhibiting breakdown of bone
What is TSH (thyroid stimulating hormone)
a hormone produced via the pituitary gland which stimulates the thyroid gland to produce T3 and T4.
It’s a negative feedback loop
What is hyPOthyroidism?
It is when your thyroid gland is underactive, leads to slowing of metabolic processes
What are the types of hyPOthyroidism?
Hashimoto’s thyroiditis - autoimmune which usualy cause primary hypothyroidism
Primary hypothyroidism - caused by the gland itself
Secondary hypothyroidism - pituitary disease
Tertiary hypothyroidism - hypothalamic disease
Explain what Hashimoto’s thyroiditis is and what it is caused by?
It’s where the thyroid gland gradually gets destroyed, it causes hyPOthyroidism.
It can be caused by an autoimmune reaction to:
thyroglobulin
thyroid peroxidase
TSH receptor
To test for hASHIMOTO’S thyroiditis test for autoantibodies against the above
How do you diagnose Hashimoto’s thyroiditis?
Carry out a blood test and check for TSH, T4 levels and anti thyroid antibodies
Symptoms of hyPOthyroidism?
fatigue
dry skin
muscle cramps
dyspnea
etc
How do you diagnose hyPOthyroidism?
Do a screening of serum TSH
If your TSH (thyroid stimulating hormone from the pituitary gland) is high, you may have primary hyPOthyroidism
If your TSH, T4, T3 levels are all low you may have a pituitary tumour so you may have secondary or tertiary hyPOthyroidism
To test for Hashimoto’s thyroiditis, test for autoantibodies against thyroglobulin, thyroid peroxidase, TSH receptor
What is the treatment for hyPOthyroidism?
Hormone replacement of the hormones T3 and T4
Keep checking TSH levels 4-8 weeks after hormone replacement
Who are the special circumstances for with hyPOthyroidism?
Pregnant women
People with Downs Syndrome
People with type 1 diabetes
This is because there is a higher incidence in these groups
What is hyPERthyroidism?
When you have an overactive thyroid gland.
It can cause Graves disease
What are some symptoms of hyPERthyroidism?
Weight loss
excessive sweating
hyperactivity
LESS common:
nausea
exacerbation of angina
what is a goiter\?
A swollen thyroid gland caused by hyPERtyroidism
How do you diagnose hyPERthyroidism?
Diffuse the goiter and if the patient HAS hyPERtyroidism, the TSH levels are suppressed and the T4 levels are elevated
Treatment for hyPERthyroidism?
Radioactive synthesis - however this can cause hyPOtyroidism in the future
Carry out surgery on large goiters
Propylthiouracil - to block the synthesis of thyroid hormones (T3, T4) to stop the thyroid gland from being too overactive
Propanolol - used to treat and reduce symptoms such as anxiety, trembling etc
What is thyroiditis?
It’s caused by a viral infection
Presents as a tender thyroid
