2728084
Description
Mind Map by Alix Stonehouse, updated more than 1 year ago
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Created by Alix Stonehouse
over 9 years ago
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ENDOCRINOLOGY
(thyroid gland)
- Thyroid hormone
- Released in response to thyroid
stimulating hormone from the
anterior pituitary which in turn is
stimulated by thyroid regulating
hormone from the hypothalamus
- Include T3 (triiodotyrosine)
and T4 (thryoxine)
- Made in follicles of the thyroid gland
made up of follicular cells surrounded by a
central, protein rich colloid
- Between these are C cells that synthesise and secrete
calcitonin. Calcitonin is secreted when calcium levels are
high. Inhibits osteoclast and stimulates calcium excretion by
the kidneys. This is important for growth in children
- Parathyroid glands are made
up of chief calls that secrete
parathyroid hormone when
calcium levels are low
- PTH mobilises calcium from bone by
increasing osteoclast activity and increasing
growth factor RANKL. Enhances calcium
reabsorption at the kidneys.
- Stimulates calcitriol that enhances calcium and phosphate
absorption from the digestive tract. Calcitriol is synthesised from D3
in the kidneys
- Stimulates calcitriol that enhances calcium and phosphate
absorption from the digestive tract. Calcitriol is synthesised from D3
in the kidneys
- High calcium levels stop
PTH by negative
feedback
- Hyperparathyroidism causes hypercalcemia. Symptoms
include fatigue, confusion, calcification of kidneys and
soft tissue. Treatments involves parathyroid removal,
calcitonin administration and hypertonic fluid
- Hypoparathyroidism causes hypocalcaemia. Symptoms include muscle
spasms, weak heart beat and osteoporosis. Treatments involve calcium
supplements and vitamin D
- PTH mobilises calcium from bone by
increasing osteoclast activity and increasing
growth factor RANKL. Enhances calcium
reabsorption at the kidneys.
- Normal calcium levels =
2.3-2.4mmol/l (cells)
1.4mmol/l (plasma)
- Parathyroid glands are made
up of chief calls that secrete
parathyroid hormone when
calcium levels are low
- Thyroglobulin proteins become iodinated to
monoiodotyrosine and diiodotyrosine from iodine in
the diet and these join to form T3 or T4. These are
taken into follicular cells at the apical surface
- T4 is produced in greater concentrations than T3 but
T3 is four times more poten. T4 is therefore converted
to T3 by liver or target tissue
- TSH binds to Gs receptors.
Protein kinase sequences cause
the release of T3 and T4 from
thyroglobulin to the blood at the
basolateral surface
- TSH secretion stops when levels of
T4 become high - negative feedback
- TSH secretion stops when levels of
T4 become high - negative feedback
- Thyroid hormones are lipophilic and so bind to
intracellular receptors on the nucleus of
mitochondria
- This causes increased protein synthesis, cell growth and maturation,
increased metabolic rate, increased oxygen consumption, increased
cardiac output, heart rate and force of contraction, thermogenesis and
increased sensitivity to sympathetic stimulation
- In children this causes a rise in body
temperature - survival technique
- This causes increased protein synthesis, cell growth and maturation,
increased metabolic rate, increased oxygen consumption, increased
cardiac output, heart rate and force of contraction, thermogenesis and
increased sensitivity to sympathetic stimulation
- Hypothyroidism -
underactive thyroid
- Caused by the immune system attacking the thyroid
gland. This causes fatigue, weight gain, feeling cold,
dry skin and hair, heavy periods, constipation and
slowed thinking
- May be central (low TSH) or primary (low T4 levels)
- Treatment includes giving thyroxine and T3
orally. Overdose can lead to angina, cardiac
dysrhythmia or hyperthyroidism
- Caused by the immune system attacking the thyroid
gland. This causes fatigue, weight gain, feeling cold,
dry skin and hair, heavy periods, constipation and
slowed thinking
- Hyperthyroidism -
overactive thyroid
- Can be due to
Grave's disease which
is also associated
with Graves
opthalmopathy
- Symptoms include shaking, nervousness, irritability, rapid
heart beat, feeling hot, weight loss, fatigue, frequent bowel
movements and fatigue
- Treatment involves beta blockers such as propranolol to reduce heart
palpitations, anti thyroid drugs such as carbamizole which affects the
synthesis, propylthiouracil and methimazole
- May also be treated with iodine
- May also be treated with iodine
- Can be due to
Grave's disease which
is also associated
with Graves
opthalmopathy
- T4 is produced in greater concentrations than T3 but
T3 is four times more poten. T4 is therefore converted
to T3 by liver or target tissue
- Between these are C cells that synthesise and secrete
calcitonin. Calcitonin is secreted when calcium levels are
high. Inhibits osteoclast and stimulates calcium excretion by
the kidneys. This is important for growth in children
- Made in follicles of the thyroid gland
made up of follicular cells surrounded by a
central, protein rich colloid
- Released in response to thyroid
stimulating hormone from the
anterior pituitary which in turn is
stimulated by thyroid regulating
hormone from the hypothalamus
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