Endocrine Flashcards
Hormone
Chemical messengers produced in one location and transported via the blood stream where they cause a response in the target cells
Name examples of Water-soluble hormones(not exact)
peptides, catecholamines
Name examples of lipid soluble hormones
steroids, thyroid hormones
how are water hormones stored and how are they transported?
they are made and stored as required (released by exocytosis).
they travel dissolved in the blood.
how are lipid hormones stored and how are they transported?
steroid hormones are made from cholestrol as required.
EXCEPTION: Thyroid hormones are made in thyroid cells and stored.
they travel bound to carriers in the blood.
where are water soluble hormone receptors located
Located on cell membrane
where are lipid soluble hormone receptors located
located inside the cell
describe water soluble receptor process
Hormone binding allows activation of associated G protein which activates/inhibits second messenger pathway, causing a cellular response.
describe lipid soluble receptor process
lipid soluble hormone binding to intracellular receptors acts as a specific transcription factor, activating the target gene, which generates new mRNA, which synthesises a protein which causes cellular response.
how long do water soluble hormones take
milliseconds to minutes
how long do lipid soluble hormones take
hours to days
amount of hormone in blood depends on
rate of hormone secretion and rate of removal from blood
what kind of hormone is insulin
peptide (water soluble)
How is the hypothalamus connected to the posterior pituitary gland?
With neurons
Where are posterior pituitary hormones made and where are they stored?
They are made in the hypothalamus and stored in the axon endings in the posterior pituitary.
How are posterior lobe hormones released
Neural communication with the hypothalamus stimulates the release of hormones
Examples of posterior pituitary hormones
Antidieuretic and oxytocin
where are anterior pituitary hormones produced
in the anterior pituitary gland
how is the hypothalamus connected to the anterior pituitary gland
blood vessels
When are growth hormones highest
puberty
Growth hormone pathway
GH-RH –> GH –> incr in metabolism, release of Somatosedin C incr growth –> inhibition of GH-RH
what hormones are made and secreted from the thyroid gland
Thyroid hormone and Calcitonin
where are thyroid hormones synthesised
thyroid follicular cells
what do clear cells produce
calcitonin
How are thyroid hormones produced
- Thyroglobulin (TGB) is produced in the follicles and contains Tyrosine
- Iodine enters follicular cells from the blood and reacts with Tyrosine
- Thyroid hormone can detach from iodised TGB as required, T3 is active, T4 is inactive
- T3 and T4 hormones travel in the blood bound to carriers (TBG Thyroid binding globulin)
describe thyroid hormone pathway
stimulus: external or internal
Hypothalamus (T-RH) –> Anterior Pituitary (T-SH) –> Thyroid (T3 and T4) –> increase basal metabolic rate, stimulate growth, normal alertness and reflexes
What are the effects of thyroid hormone
- increased body heat production
- stimulates fatty acid oxidation (usage)
- increases proteolysis
- stimulates carbohydrate metabolism
Describe the pathway of Blood calcium homeostasis
decr in blood calcium –> parathyroid glands: PTH –>
effects:
Kidney
1. incr calcium reabsorption into blood which decreases calcium excreted in urine.
2. vitamin D and calcitriol increase calcium reabsorption from food in intestines
Bone:
1. Increase bone breakdown, which increases release of Ca into the blood
This then increases blood calcium levels which inhibits decrease in blood calcium.
where is adrenaline secreted from
adrenal medulla
where is cortisol secreted from
adrenal cortex
where is the adrenal glands found
superior to the kidney
what kind of hormone is adrenaline
water soluble catecholamines
adrenaline pathway
stress –> hypothalamus –> sympathetic preganglionic fibres –> adrenal medulla: adrenaline –> metabolic effects
Skeletal muscle/liver:
incr glycogenolysis
Fat:
incr fat breakdown
where are the parathyroid glands located
on the posterior of the thyroid glands
what kind of hormone is cortisol
lipid soluble steroid
when are cortisol levels highest
during waking
cortisol pathway
non-stress neural inputs e.g day-night rhythms –> hypothalamus: CRH –> anterior pituitary: ACTH –> adrenal cortex: cortisol –> metabolic effects
Muscle:
incr protein breakdown
decr glucose uptake
Fat:
incr fat breakdown
decr glucose uptake
Liver:
incr glucose synthesis
ADH pathway
stress –> hypothalamus neural stimulation –> posterior pituitary: ADH –> metabolic effects
Decr urination
Incr blood volume and blood pressure
What is Addison’s Disease caused by
Autoimmunity: Hyposecretion of cortisol and aldosterone
Effects of Addisons Disease
- Low blood pressure
- Weakness due to lack of fuel
Decr in cortisol leads to incr of ATCH, this excess ACTH stimulates melanin synthesis which causes darker skin.
Causes of Cushing’s Disease
Hypersecretion of cortisol caused by Tumors
Symptoms of Cushing’s disease
- Buffalo Hump
- Moonface
- High blood pressure
- Weakness (muscle wasting)
Cause of Gigantism
Hypersecretion of growth hormone.
Symptoms of gigantism
Much taller and some extra bony formations in the face.
Cause of primordial dwarfism
Hyposecretion of GH.
Cause of Infantile Hypothyroidism
Not enough iodine in mother’s diet. Hyposecretion of Thyroid hormone
Symptoms of Infantile Hypothyroidism
- cold intolerance
- low metabolic rate
- growth is retarded
- brain development is inhibited
Cause of Iodine Deficiency Disorder (Simple Goitre)
Not enough iodine in diet. Hyposecretion of thyroid hormone.
Effects of Iodine Deficiency disorder (simple goitre)
Decr in TH, means TRH and TSH secretion increases. Excess TSH stimulates growth of thyroid gland (goitre).
Loss of negative feedback control
Causes of Grave’s Disease
Autoimmune: hyper secretion of thyroid hormone
Symptoms of Grave’s disease
- high metabolic rate
- weight loss
Causes of Hyperparathyroidism
Tumors: hypersecretion of parathyroid hormone
Symptoms of hyperparathyroidism
- excess PTH secretion
- bones become soft, deformed and fragile
- raises blood levels of calcium and phosphate ions
- promotes formation of kidney stones composed of calcium phosphate
Hypercalcaemia cause
Tumors: blood calcium levels are too high
Effects of Hypercalcaemia
- Nerve and muscle cells less responsive and excitable
- can lead to enotional disturbances
- muscle weakness
- sluggish reflexes
- cardiac arrest
Hypocalcemia causes
Vitamin D deficiency
Diarrhoea
Thyroid tumors
Underactive paraythyroid glands
Pregancy
Effects of Hypocalcemia
Increased excitability of the nervous system
Leads to muscle tremors, spasms or cramps
Suffication
Diabetes mellitus
Type 1 and Type 2
Type 1 Diabetes Mellitus
Hyposecretion of insulin (too little or no insulin secreted)
Causes by destruction of pancretic beta cells by immune system
Symptoms:
- Glucosuria, polyuria
Treated with insulin injections
Type 2 diabetes mellitus
Hyposensitivity: too little or no response to insulin
Cause: desensitisation of insulin receptor. obesity
Symptoms:
- glucosuria, polyuria
Treatment:
changes in diet and excersise.
various medications
