BIOC0006: ENDOCRINOLOGY REVISION NOTES FOR EXAM PREPARATION
What is the endocrine system?
Collection of glands that secrete chemical message, which is a hormone. Hormone is
released into blood circulation to be transported to the target cell
What is the function of hormones?
1. Maintains homeostasis and long-term control using chemical signals
2. Works in parallel with the nervous system to control homeostasis
How can hormones be grouped into?
peptides - short chains of amino acids; most hormones are peptides, secreted by the
pituitary,
parathyroid, heart, stomach, liver, and kidneys.
amines - derived from the amino acid tyrosine and are secreted from the thyroid and
the adrenal
medulla.
steroids - lipids derived from cholesterol. Testosterone is the male sex hormone.
Oestradiol, similar
in structure to testosterone, is responsible for many female sex characteristics. Steroid
hormones are secreted by the gonads, adrenal cortex, and placenta.
What is the mechainism of hormone action?
1. The endocrine system acts by releasing hormones that in turn trigger actions in
specific target cells.
2. Hormone binds to the receptor of the target cells.
3. The binding hormone changes the shape of the receptor causing the response to the
hormone.
What is the difference between paracrine and autocrine hormone?
Paracrine hormone released to trigger response of nearby target cell
Autocrine hormone released to rigger self-reposnes
What is non-steroid signnaling?
- Non-steroid hormones are hydrophilic molecules
- The receptors of non-steroid hormones are plasma
membrane receptors, activation of plasma membrane receptors generating a chemical
signal (2nd messengers) in the targets cell.
- Five different second messenger chemicals, including cyclic AMP and IP3 have been
identified. Second messengers activate other intracellular chemicals to produce the
target cell response.
What is steroid signalling?
- steroid hormones are hydrophobic molecules, which are able to pass through the
plasma membranes.
- The hormone binds to the nuclear membrane receptors, producing an activated
hormone-receptor complex.
- The activated hormone-receptor complex binds to DNA and activates specific
genes, increasing production of proteins
What are the two types of endrocrine related problems?
, - Overproduction/underproduction of a hormone (hormonal problem)
- Non-functional receptors that cause target cells to become insensitive to hormones
(receptor problem)
What is the structure of posterior pituitary gland?
directly connected to the hypothalamus via Hypothalamo-hypopheseal (Supra-optic
hypothalamic tract)
How is the hormone synthesised and released from pituitary gland?
- The posterior pituitary itself does not synthesis hormone, but acting as
the storage site of hormone vasopressin and oxytocin.
- Hormones are actually synthesised in the hypothalamus, specifically the cell bodies of
magnocellular neurones. This include paraventricular nuclei (PVN) and supraoptic
nucleus (SON).
- Then the hormones are packed into granules and transported to posterior pituirary
gland along with the carrier protein knwon as neurophysin.
- The transportation occrs by axonal transport along the axons of the magnocellular
nuerons to their nerve termnal in the posterior lobe
What is the secretion of vasopressin and oxytocin depend on?
calcium
What are the difference, in terms of structure, of oxytocin and vasopressin?
The phenylalanine and arginine residue in AVP is changed to isoleucine and leucine in
oxytocin.
What are the receptor type for vasopressin
V1 (mainly V1A type mediating the effect of vasopressin on vascular smooth muscle ->
blood pressure)
V2 (regulate ACTH secretion -> water reabsorption)
Overall effect is to aid water reabsorption by the kidney
What are the other name of vasopressin?
Anti-diuretic hormone
arginine vasopressin - to distinguish it from ADH produced by other species
What is the function of oxytocin?
1. Stimulates milk ejection (milk let-down)
2. Uterosu smooth muscle contraction at birth
3. establish of maternal behaviour
What is the 1. full name; 2. cell population that secrete it; and 3. its function of
TSH?
1. Thyroid-stimulating hormone
2. Thyrotrophs
3. Stimulates the syntehsis and secretion of thryoid hormones
What is the 1. full name; 2. cell population that secrete it; and 3. its function of LH
and FSH?
1. Luteinizing hormones, and follicle-stimualting hormone
2. Gonadotrophs
3. Stimualte steroid biosynthesis and germ cell maturation in the gonads
What is the endocrine system?
Collection of glands that secrete chemical message, which is a hormone. Hormone is
released into blood circulation to be transported to the target cell
What is the function of hormones?
1. Maintains homeostasis and long-term control using chemical signals
2. Works in parallel with the nervous system to control homeostasis
How can hormones be grouped into?
peptides - short chains of amino acids; most hormones are peptides, secreted by the
pituitary,
parathyroid, heart, stomach, liver, and kidneys.
amines - derived from the amino acid tyrosine and are secreted from the thyroid and
the adrenal
medulla.
steroids - lipids derived from cholesterol. Testosterone is the male sex hormone.
Oestradiol, similar
in structure to testosterone, is responsible for many female sex characteristics. Steroid
hormones are secreted by the gonads, adrenal cortex, and placenta.
What is the mechainism of hormone action?
1. The endocrine system acts by releasing hormones that in turn trigger actions in
specific target cells.
2. Hormone binds to the receptor of the target cells.
3. The binding hormone changes the shape of the receptor causing the response to the
hormone.
What is the difference between paracrine and autocrine hormone?
Paracrine hormone released to trigger response of nearby target cell
Autocrine hormone released to rigger self-reposnes
What is non-steroid signnaling?
- Non-steroid hormones are hydrophilic molecules
- The receptors of non-steroid hormones are plasma
membrane receptors, activation of plasma membrane receptors generating a chemical
signal (2nd messengers) in the targets cell.
- Five different second messenger chemicals, including cyclic AMP and IP3 have been
identified. Second messengers activate other intracellular chemicals to produce the
target cell response.
What is steroid signalling?
- steroid hormones are hydrophobic molecules, which are able to pass through the
plasma membranes.
- The hormone binds to the nuclear membrane receptors, producing an activated
hormone-receptor complex.
- The activated hormone-receptor complex binds to DNA and activates specific
genes, increasing production of proteins
What are the two types of endrocrine related problems?
, - Overproduction/underproduction of a hormone (hormonal problem)
- Non-functional receptors that cause target cells to become insensitive to hormones
(receptor problem)
What is the structure of posterior pituitary gland?
directly connected to the hypothalamus via Hypothalamo-hypopheseal (Supra-optic
hypothalamic tract)
How is the hormone synthesised and released from pituitary gland?
- The posterior pituitary itself does not synthesis hormone, but acting as
the storage site of hormone vasopressin and oxytocin.
- Hormones are actually synthesised in the hypothalamus, specifically the cell bodies of
magnocellular neurones. This include paraventricular nuclei (PVN) and supraoptic
nucleus (SON).
- Then the hormones are packed into granules and transported to posterior pituirary
gland along with the carrier protein knwon as neurophysin.
- The transportation occrs by axonal transport along the axons of the magnocellular
nuerons to their nerve termnal in the posterior lobe
What is the secretion of vasopressin and oxytocin depend on?
calcium
What are the difference, in terms of structure, of oxytocin and vasopressin?
The phenylalanine and arginine residue in AVP is changed to isoleucine and leucine in
oxytocin.
What are the receptor type for vasopressin
V1 (mainly V1A type mediating the effect of vasopressin on vascular smooth muscle ->
blood pressure)
V2 (regulate ACTH secretion -> water reabsorption)
Overall effect is to aid water reabsorption by the kidney
What are the other name of vasopressin?
Anti-diuretic hormone
arginine vasopressin - to distinguish it from ADH produced by other species
What is the function of oxytocin?
1. Stimulates milk ejection (milk let-down)
2. Uterosu smooth muscle contraction at birth
3. establish of maternal behaviour
What is the 1. full name; 2. cell population that secrete it; and 3. its function of
TSH?
1. Thyroid-stimulating hormone
2. Thyrotrophs
3. Stimulates the syntehsis and secretion of thryoid hormones
What is the 1. full name; 2. cell population that secrete it; and 3. its function of LH
and FSH?
1. Luteinizing hormones, and follicle-stimualting hormone
2. Gonadotrophs
3. Stimualte steroid biosynthesis and germ cell maturation in the gonads
