W9 Endocrine System Flashcards
What are the different intracellular messenger systems? (5)
Neurotransmission
Neuroendocrine
Endocrine
Autocrine
Paracrine
What is an example of a…
neurotransmitter?
neuroendocrine transmitter?
Endocrine transmitter?
Autocrine transmitter?
Paracrine transmitter?
Neurotransmission- noradrenaline, acetylcholine
Neuroendocrine- Oxytocin and ADH
Endocrine- Insulin, TSH, thyroxine, cortisol
Autocrine- Prostoglandins
Paracrine- Glucagon, somatostatins
What do hormones do?
Where are they secreted?
“Arouse or Excite”
Glands secrete hormones directly into blood stream (ductless)
Carried to target cells/tissue (away) from the endocrine gland
What is the structure of a peptide hormone?
Where are they secreted
Small chains
Large chains
Mostly secreted from hypothalamus, pituitary, pancreas and GIT
Peptide hormones:
How are they synthesised and stored?
How are they transported?
How are they adapted for transport? (4)
Synthesis: like any protein synthesis
Transcription/Translation
preprohormone-prohormone-hormone-secretory
granules/vesicles
Stored in the cells
Release: Require stimuli
Exocytosis
Transport:
Hydrophilic,
Freely circulate in the blood vessel
No plasma protein binding
Short Half-life: minutes
How are steroidal hormones synthesised?
How are they released/transported?
How are they adapted for transport? (3)
Chemical structure- Cholesterol as the base
Synthesis- Like any steroidal synthesis
Enzymatic conversion of precursor (cholesterol base) molecules into hormone
Not stored in the cells
Release:
Stimulus increase precursor level and enzyme activation
Simple diffusion across membrane
Transport:
-Lipophilic
-Binds with Plasma protein
-Half-life: hours to days
When is a molecule inactive?
How can you activate it?
Any molecule BOUND to a PLASMA PROTEIN it becomes inactive.
In order to activate it, steroidal hormone must be released from carrier protein
What is tyrosine?
How is it transported?
How is it adapted for transport?
Chemical structure: tyrosine as the base
thyroid hormones and catecholamines (adrenal medulla)
Release
Stimulus required
Simple diffusion across membrane
Transport
Lipophilic
Binds with Plasma protein (Weak and reversible bonds)
Half-life: hours to days
What are eicosanoids?
How do they travel across the cell membrane?
How are they adapted for transport?
Chemical structure: Polyunsaturated fatty acid derivatives
Eg; prostaglandins, leukotrienes, prostacyclins and thromboxanes
Synthesis:
Precursor- Arachidonic acid (membrane lipid)
Enzymes- Lipase dictates the production of various eicosanoids
Release:
Stimulus required
Poorly diffuse through cell membrane
Transport:
Eicosanoids require transporter (anionic)
Half-life: in seconds: rapidly inactivated: Limited to autocrine and paracrine effects
Synthesized by stereo- and regio-specific peroxidation of arachidonic acid by three enzyme
families namely lipoxygenases, cyclooxygenases, and cytochrome P450
Hormonal homeostasis
Peptide hormone function
Hormonal Homeostasis
What is negative and positive feedback?
Negative- OUTCOME negatively controls PROCESS (maintain a set-threshold)
Positive feedback- OUTCOME amplifies the PROCESS
Hypothalamus -Pituitary axis
Hypothalamus—CRH released— Anterior Pituitary— ACTH released—Peripheral Endocrine Gland—Cortisol—Target cells (response)
What type of hormone is released by anterior pituitary?
Peptide hormone
Hormonal homeostasis consists of what? (4)
Simple Feedback Axis
Hypothalamus-Pituitary- Axis
Neuroendocrine reflux’s
Circadian Rhythms (diurnal- sleep and wake
cycle)
Metabolism of Hormones
Enzymatic processes:
Largely in blood, liver and kidney and some in target
cells/tissues/organs
Excreted in urine.
Hyposecretion example
Type l diabetes
What is an example of Hypersecretion?
Tumors
What is located on the peripheral gland?
Primary defect
High ACTH secreted means..
Increases cortisol production
Negative feedback at hypothalamus (CRH is low)
Secondary defect
What causes an Endocrine disorder?
Give an example
Tumour in peripheral gland (primary) or pituitary (secondary) or ectopic
Immunological (& genetic): Autoimmune disease (eg: T1DM, Hashimoto’s, Graves’, Addison’s)
Treatment strategies:
Hyposecretion
Hypersecretion
Impaired target-cell responsiveness
Tumour
- Hyposecretion/hormone deficiency – Replace the hormone (supplements)
- Hypersecretion/hormone excess – Block the synthesis and release (drugs)
- Impaired target-cell responsiveness – drugs to enhance cellular response to hormone
- Tumour – radiotherapy or surgery
Primary defect
Low ACTH and CRH
High Cortisol
What is a Secondary defect?
Low CRH
High ACTH and Cortisol
Four types of Hormones
Peptide
Steroidal
Tyrosine containing
Eicosanoids
Hypothalamus -Pituitary
Cell bodies and the neurons responsible for the secretion of hypothalamic releasing factors (hormones)
Hypothalamus-Anterior Pituitary
Where do releasing factors pass to?
Releasing factors pass along the portal vessels to reach capillary bed of the anterior pituitary, to control secretion of anterior pituitary hormones
Hypothalamus Posterior-Pituitary
Paraventricular (PVN) and
supraoptic (SON) nuclei,
and the neurons carrying
oxytocin and ADH
(vasopressin) to the
posterior pituitary, where
they are stored/ released
Pituitary gland clinical relevance
Pituitary tumours are mostly benign and slow-growing
Over/under production of hormones (Hyper/Hypo)
Local effects: pressure on surrounding structures
– headaches, visual disturbances
Somatotropin, HGH
What is it secreted by?
How is it stored?
What is its role?
What is its stimulus for growth?
Secreted by acidophilic cells of anterior pituitary glands
It is stored in the cells as granules. Growth hormone production is pulsatile
Peptide hormone: 21.5 K Da single-chain polypeptide (190 AA) with 2 disulphide bridges)
Major role in growth (linear) & metabolism
Drop in blood glucose is the stimulus for the growth of HGH (human growth hormone)
What is gluconeogenesis?
What type of process is it?
endogenous process in the liver
production of glucose from amino acids and glycerol
How does HGH work?
Direct-on metabolism:
Inc Gluconeogenesis in liver
Inc protein synthesis
Indirect-growth
(Insulin-like growth factors (somatomedins) from liver)
Increases Hypertrophy (cell size)
protein synthesis, Hyperplasia(cell number), Cell division, Skeletal growth
What is Dwarfism?
What are the psychological changes?
Stunted growth
Psychological changes
* Malaise, excessive tiredness, anxiety and
depression
* Osteoporosis
* Poor muscular tone, decrease in lean body
mass
* Impaired hair growth
* Increase in adipose tissue (especially around
the waist)
What are the symptoms of Gigantism (in children) or Acromegaly (in adults)?
- coarsening of facial features
- enlarged hands and feet
- headaches, vision disturbance
- sleep apnoea, general tiredness
- hypertension, cardiomegaly
- glucose intolerance (diabetes)
- irregular or loss of periods (females);
impotence (males)
Thyroid hormones” – thyroxine (T4) and tri-iodothyronine (T3)
- calcitonin & parathyroid hormone (PTH)
Thyroid hormones” – thyroxine (T4) and tri-iodothyronine (T3)
- calcitonin & parathyroid hormone (PTH)
The production of T3 and T4 from tyrosine
T4- more dependant (needs to be de-iodonated to become T3)
T3- most active thread hormone
T3 is a Thyroid hormone.
What does T3 stand for?
What are its functions? (3)
Tri-iodothyronine
- Growth & Development: CNS
- Basal Metabolic Rate (BMR): Sugar, Fat, Protein
- Synergistic effect with sympathetic/catecholamine (T3 increase the expression adrenergic receptors)
Goitre definition
2 types of goitre?
Enlarged thyroid gland
Diffuse and nodular
What does aldosterone regulate?
Sodium and water homeostasis
It increases sodium and water absorption in the kidney.
Hormones of adrenal gland:
1.What is in the Zona glomerulosa: (top)
2. Zona fasciculata:
3. Zona reticularis:
4. Chromatin cells: (bottom)
- Mineralocorticoids (Mineral Balance)
Aldosterone - Glucocorticoids (Glucose Metabolism)
Cortisol - Androgens (Masculinisation)
Dehydroepiandrosterone - Catecholamines (Sympathetic activation)
Adrenaline/Noradrenaline
What type of hormone is cortisol and what does it regulate?
Steroid hormone
Glucose metabolism
What does excess glucocorticoids cause?
Which hormone is involved?
What are the symptoms?
Cushing’s syndrome (Excess cortisol)
- ACTH-secreting pituitary hormone
(based on Minnie G)
Purple striae, Upper body obesity with thin arms and legs, Buffalo Hump,
What does adrenal insufficiency cause?
(Autoimmune disease or by HIV or TB) –not producing
sufficient, cortisol, aldosterone and androgens
Addison’s disease
Lowers:
Hair Loss
Blurred vision
Abdominal pain
Decreased appetite
Darkening of the skin
Weight Loss
Hypoglycaemia
Postural Hypotension
- ACTH production increased, as is MSH
(share same POMC-precursor as ACTH)
→ increase melanin content in skin
Anterior pituitary hormones examples
Thyroxin (thyroid gland)
Growth hormone
Melanocyte-stimulating hormone
Posterior pituitary hormones are…
Examples?
Neural hormones. They are not secreted from the PPT but are released from here.
ADH (vasopressin) and Oxytocin
What is ADH stimulated by?
Function?
Stimulated by Hypovolemia, Hyperosmolality and Hypotension
Increase permeability and hence re-absorption of water.
Stimulate ACTH release
Blood vessels – vasoconstriction (at higher [ADH])
Low ADH
diabetes insipidus (DI): polyuria and
polydipsia (Excessive urination and Excess thirst)
* Pituitary DI:
Inadequate release of ADH
* Nephrogenic DI:
Dysfunction of receptors in collecting ducts
What are the problems associated with High ADH?
Syndrome of inappropriate ADH secretion (SIADH)
CNS pathologies, malignancy, CNS drugs
Retention of water in the body,
Highly concentrated urine
Hyponaterimia (dilution effect not
sodium loss)
Which one of the following in a peptide hormone?
Cortisol, insulin, thyroxine, prolactin, adrenaline
Insulin
What type of hormone is
thyroxine
Prostoglandin
Aldosterone
Prolactin
Insulin
Thyroxine- tyrosine containing
Prostoglandin- eicosanoid
Aldosterone- steroidal
Prolactin- peptide
Insulin- peptide
Where is prolactin secreted from?
What type of hormone is it?
Anterior pituitary gland
Peptide
What is somatotropin?
HGH- human growth hormone
What is Cushing’s syndrome?
Excess glucocorticoids secretions
What is Dwarfism?
What is Acromegaly or Gigantism?
Hyposecretion of growth hormone.
Excess secretion of somatotropin/HGH
What is Addison’s disease?
(Darkening of skin)
Adrenal insufficiency-not producing sufficient, cortisol, aldosterone and androgens
- ACTH production increased, as is MSH
(share same POMC-precursor as ACTH)
→ increase melanin content in skin
What is prolactin and its function?
What is prolactinoma?
Symptoms?
-A pituitary hormone which stimulates the mammary glands to produce milk and growth of the breast tissue.
-Excess secretion of prolactin from pituitary gland
-Infertility/libido/galactorrhoea
What is Cushing’s syndrome? (simple)
excess glucocorticoids secretions
What is Conn’s syndrome? (simple)
excess aldosterone
What is Dwarfism? (simple)
hyposecretion of growth hormone
What is Prolactinoma? (simple)
excess secretion of prolactin from anterior pituitary gland
What is Diabetes inspidus? (simple)
Hyposecretion of antidiuretic hormone (ADH) or arginine vasopressin (AVP)
What is Diabetes mellitus?
Hyposecretion insulin from beta cells or insulin resistance
What is Cretinism? (simple)
Poor development of CNS in perinatal due to hyposecretion of T3
What is Hashimoto’s thyroiditis? (simple)
Primary failure of thyroid gland, hyposecretion of thyroid hormones from thyroid glands
What is Acromegaly? (simple)
Excess secretion of somatotropin (HGH)
What is Addison’s disease (simple)
Adrenal insufficiency, not producing sufficient adrenal hormone
What is Graves disease? (simple)
Hyper secretion of thyroid hormones due to an autoimmune condition of Thyroid Stimulating Immunoglobulins (TSI)
Which ONE of the following hormones is primary responsible for glucose utilisation?
Cortisol
Aldosterone
Testosterone
Glucagon
Insulin
Insulin
Ms. Honey, a 52-year-old lady has been diagnosed for exophthalmos (protruding of eyes) and her case file revealed that she had the other conditions including nervousness, palpitations, weight loss, tremor, sweating and heat intolerance.
She also had the enlarged thyroid gland (goitre). Her blood report revealed that the thyroid hormones (T3 and T4) levels were higher than the normal/reference level. However, the thyroid stimulation hormone (TSH) level was lower than the reference range.
What is a likelihood diagnosis for Ms. Honey’s health condition?
Grave’s disease
The deficiency of a neural hormone secreted from posterior pituitary, antidiuretic hormone (ADH) leads to polyuria and polydipsia and this condition is referred as__________
Central diabetes insipidus
What is the specific endocrine function of these hormones?
Growth hormone
T3, triiodothyronine
Aldosterone
- Regulate linear skeletal growth
- Regulate basal metabolic rates (BMR)
- Regulate salt, water balance and blood pressure
What is the specific endocrine function of these hormones?
Adrenaline
Cortisol
Parathyroid hormone
-Regulates heart rate and blood pressure
-Regulates body’s stress response
-Regulate calcium homeostasis
What is the specific endocrine function of these hormones?
Insulin
Oxytocin
Antidiuretic hormone (ADH)
Lowers blood glucose
Regulate milk secretion and contraction of uterus
Regulates water retention and blood pressure
What is the specific endocrine function of these hormones?
Prolactin
Erythropoietin
-Regulates milk production
-Regulate red blood cells production
Which hormones increases the expression of β-adrenergic receptors and synergistically increase catecholamine effects on the heart rate and blood pressure?
- T3, triiodothyronine
- TSH
- T4, thyroxine
T3, triiodothyronine
A primary aldosteronism is also called _______________, is a rare condition caused by overproduction of the hormone aldosterone that controls sodium and potassium in the blood.
- Conn’s syndrome
- Crohn’s diease
- Addison’s disease
- Cushing’s disease
Conn’s syndrome
What is the hormonal basis for acromegaly? (2 marks)
excessive growth hormone (GH) production, usually caused by a benign pituitary adenoma
What are the key signs and symptoms of acromegaly (3 marks)
- A gradual change in facial features (prominent brow, large nose, lips, tongue and protruding jaw)
- Overgrowth of the hands and feet, developing over a period of years
- symptoms of glucose intolerance (diabetes)
- arthritic pain in the extremities.
Identify the similarities and differences between Peptide, Steroidal and Thyroid containing hormones:
Peptide:
Cont 3 or more amino acids
Circulate as free hormone
Bind to plasma proteins on target cells
Act on surface receptors
Steroidal and Thyroid:
Lipophilic and diffuse through plasma membrane
Circulate bound to plasma hormone-binding proteins
Act on intracellular receptors/transcriptiojn factors
What 5 hormones does the anterior pituitary secrete?
GH, TSH, ACTH and LH/FSH
