Hormones Flashcards
(216 cards)
1
Q
What is the endocrine system
A
Organs that secrete a hormone into the blood are called endocrine glands. Release ‘chemical messengers’
2
Q
Hormone action on a whole body level
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Regulation and integration of: ionic and fluid balance, energy balance (metabolism), coping with the environment, growth and development, reproduction.
3
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Hormone action on a molecular level
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Regulation of: gene transcription, prote4in synthesis and degradation, enzyme activity, protein conformation, protein to protein interactions
4
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Hormone action on a cellular level
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Regulation: cell division, differentiation, death (apoptosis), motility, secretion, nutrient uptake
5
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Steroid hormone examples
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testosterone, oestrogen and cortisol - cholesterol derived
6
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Peptide hormone examples
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growth hormone, oxytocin and parathyroid hormone
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Amino acid derived hormone examples
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thyroid hormones and catelcholamines
8
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Steroid hormone - location of receptor
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cytosol or nucleus
9
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peptide hormone - location of receptor
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cell surface
10
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Steroid hormone mechanism of action
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Bind DNA/ modify transcription
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Peptide hormone mechanism of action
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secondary messenger - cAMP
12
Q
Which hormone has a faster response
A
peptide hormones
13
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Longevity effects of the hormones
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steroid - more permanent. Peptide - temporary
14
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Hormone negative feedback system
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hypothalamus stimulates pituitary gland which stimulates an endocrine gland. Negative feedback is seen when the output of a pathway inhibits inputs to the pathway
15
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Examples of some positive feedback loops
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oxytocin and parturition
16
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Location of the pituitary galnd
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inferior (below) the hypothalamus with the optic chiasm between
17
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Anterior lobe (pars distalis) of pituitary gland
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portal blood vessels connect pituitary and hypothalamic capillary beds
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Posterior lobe (pars nervosa) - pituitary gland
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nerve fibers originate in the hypothalamus and transport hormones to posterior pituitary
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Sections of the anterior pituitary
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pars tuberalis, pars intermedia, pars distalis
20
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Sections of the posterior pituitary
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infundibular stalk, pars nervosa
21
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Which 2 hormones does the posterior pituitary scerete
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oxytocin and vasopressin (anti-diuretic hormone, ADH)
22
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Oxytocin function
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controls milk release from lactating breast. Controls uterine contraction at onset of labout
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ADH function
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acts on kidneys to reabsorb water
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Cell bodies of the posterior pituitary
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paraventricular nucleus and supraoptic nucleus - both produce hormones
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What does the interaction of oxytocin with its receptors do
raises the levels of intracellular calcium in the myoepithelial cells of the mammary gland causing myoepithelial cells to contract foricng milk into ducts
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Oxytocin timeline of events
Suckling -> hypothalamus -> posterior pituitary -> oxytocin -> milk squeezed out = neuro-endocrine reflex
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Effect of ADH on collecting duct
collecting duct is permeable to water so there is increased plasma osmolarity. Dehydration stimulates osmoreceptors in hypothalamus
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What are tropic hormones
hormones which regulate the secretions of other endocrine organs
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What 6 hormones does the anterior pituitary gland produce
Growth hormones, prolactin, adenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH), folicle stimulating hormone (FSH), luteinising hormone (LH)
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Prolactin target organs
mammary glands
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Which hormone is a corticotroph
ACTH
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Which hormone is from somatotrophs
Growth hormones
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Which hormones are from gonadotrophs
FSH and LH
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Which hormones are from thyrotrophs
Thyroid stimulating hormone
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Stimulatory compounds that the hypothalamus secretes to control anterior pituitary
corticotrophin releasing hormone (CRH), gonadotropin releasing hormone (GRH), thyrotropin releasing hormone (TRH), growth hormone releasing hormone (GHRH)
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Inhibitory compounds the hypothalamus secretes to control the anterior pituitary
dopamine (DA) (inhibits prolactin) and somatostatin (SS) (inhibits growth hormone)
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Growth hormone target
bone and skeletal muscle
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Growth hormone function
Stimulates growth in children and adolescents but continues to exert important effects throughout adult life
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Other hormones that effect growth and their affects
Thyroxine (lack inhibits growth)
Cortisol (excess inhibits growth)
Insulin (excess stimulates growth
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Do growth hormones have an anabolic or catabolic effect on metabolism
anabolic
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How do growth hormones protect against hypoglycaemia
it is glucose sparing with an anti-insulin action so can conserve growth for CNS
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Growth hormone affect on muscle
decrease glucose uptake, stimulates aa uptake/protein synthesis, inhibits protein breakdown = increased muscle mass
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Growth hormone effect on adipose tissue
decrease glucose uptake, increase lipolysis = decrease in fat tissue
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Growth hormone effect on liver
increase glycogenesis, increase protein synthesis, stimulates IGF production
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Indirect effects of growth hormone - insulin
GH actions via insulin like growth factors: growth hormone -> liver -> IGF ->
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Indirect effect of growth hormone on skeletal growth
cartilage formation, bone deposition – lengthening and thickening
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Indirect effect of growth hormone on soft tissue growth
protein synthesis, cell proliferation
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When does growth-promoting bone response to growth hormones cease
when growth plates fuse
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Somatopause (decrease in GH) effects
Decrease in lean body mass. Decline in bone mineral density. Increase in body fat
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What can cause growth hormone disorders
result of pituitary tumours
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What occurs in people with gigantism (GH excess)
abnormally high linear growth due to excessive action of IGF while the epiphyseal growth plates are open during (children)
Normally body proportions as soft tissues are also affected
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What is acromegaly
Increases growth hormone later in life after fusion of epiphyses (growth plates)
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Symptoms of acromegaly
course facial features, enlarged hands and feet, protruding jaw and separation of teeth, enlarged tongue and thickened lips, deep voice, cardiomegaly, diabetes
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Effects of GH insufficiecny in children (pituitary dwarfism)
Slow growth rate below 3rd centile on age/height or bone chart
Normal body proportions
Poor muscle development, excess subcutaneous fat
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Thyroid gland structure
adhered to the trachea. 2 large (asymmetrical) flat lobes connected by isthmus
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What regulates the thyroid gland
by hypothalamus and pituitary
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Development of the thyroid gland
Fully developed by week 12 of gestation
Responsive to TSH at 22 weeks
Capable of producing T3/T4 at 14 weeks
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What is the function of theyroid hormones
subsequent for fetal growth and development
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Thyroid gland blood supply
left superior and inferior thyroid artery. Left superior, middle and inferior thyroid vein
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Histology if thyroid gland
Functional unit = follicle (200-300um in diameter)
1000’s in each gland
Each follicle consists of a layer of follicular cells (simple cuboidal epithelial) surrounding a colloid-filled cavity
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Components of thyroid follicle
C cells secrete calcitonin, follicular cells secrete thyroid hormone, capillary, colloid is a glycoprotein, capsule of connective tissue
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What are the 2 thyroid hormones
Triiodothyronine (T3) and thyroxine (T4)
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Which thyroid hormone has a greater biological activity
T3 (about 10 x more than T4)
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How many iodine molecules does T4 contain
4
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How many iodine molecules does T3 contain
3
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What does the thyroid secrete per day
about 80-100 ug of T4, but only 5ug of T3 per day
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Why 2 raw materials is required for the synthesis if T4 and T3
tyrosines and iodine
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Sources of tyrosines
Provided by thyroglobulin
Secreted by follicular cells into lumen of follicle as colloid
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Iodine in the synthesis of T4 and T3
Iodine is pumped into follicular cells against concentration gradient (40 x blood concentration)
Dietary iodide is oxidized to iodine.
Iodine binding to tyrosine of the thyroglobulin, cuts bits off
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How much iodine is required per day
minimum of 75ug per day
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T4 and T3 synthesis (steps 1 -4)
1. Thyroglobulin is synthesized and discharged into follicle lumen
2. Iodide is actively transported in
3. Iodide is oxidized to iodine
4. Iodine is attached to tyrosine in colloid, forming DIT and MIT
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T4 and T3 synthesis (steps 5-7)
5. Iodinated tyrosines are linked together to form T3 and T4
6. Thyroglobulin colloid is endocytosed and combined with a lysosome
7. Lysosomal enzymes cleave T4 and T3 from thyroglobulin and hormones diffuse into bloodstream
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Advantages to the thyroid production system
1. Can stores week's worth of thyroid hormones
2. Thyroid secretion can be maintained if no iodine is available
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What are rich sources of iodine
processed food that contains iodized salt, seaweed, eggs, cows milk
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how much of thyroid hormone release is T4
90%
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Where does conversion of T4 into T3 occur
in peripheral tissues (liver, kidneys and skeletal muscle)
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Thyroid hormone mechanism of action
bind to intracellular receptors. Complex with thyroid response elements (TRE) that bind to DNA and influence gene expression (stimulates transcription/translation)
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Transcription of T4 and T3
Triiodothyronine moves into the nucleus where it binds to the THR. The T3-THR complex acts as a transcription factor and is able to bind directly to the DNA at sequences known as TREs. With the help of additional transcription-regulating proteins, transcription of messenger RNA (mRNA) occurs with mRNAs encoding a number of proteins involved in metabolism.
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What do the transcribed proteins triggered by thyroid hormones usually do
Increase cellular metabolism, Increase cellular oxygen consumption, Increase cellular glucose, Increase circulation and respiration, Promote nervous system and skeletal development
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What do the thyroid hormones help maintain
Energy levels, Weight, Thermoregulation, Heart rate, GI motility, Mood
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Thyroid hormone cardiovascular effects
increased cardiac output, increased heart rate and contractility
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Thyroid hormones - increased basal metabolic rate
important in temperature regulation and adaptation to cold environments. O2 consumption and heat production, increases mobilization and utilization of glucose, fat, protein.
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Thyroid hormones - growth and maturation
bone growth, synergy with growth hormone, CNS development and function, thyroid hormone deficiencies can result in mental impairment and short stature.
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Thyroid hormones - other effects
respiratory effects, skeletal muscle function, regulation of reproductive function, synergy with catecholamines.
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What does TSH do
1. Promotes release of thyroid hormones
2. Increases activity of iodide pump and iodination of tyrosine to increase production of thyroid hormones
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What is hypothyroidism
underactive thyroid. In general metabolic rate decreases and weight gain
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Hypothyroidism symptoms
dry, cold skin, sensitivity to cold, weight gain despite loss of appetite, impaired memory, mental dullness, lethargy
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hypothyroidism clinical exam
reduced metabolic rate, reduced cardiac output
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Hypothyroidism diagnosis
low plasma levels of ‘free’ T3 and T4
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Hypothyroidism treatment
thyroxine. Dose determined by TSH monitoring
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Hypothyroidism causes
iodine deficiency -> endemic goitre. Autoimmune disease -> Hashimoto’s thyroiditis. Others: congenital, post radiation/surgery, medications, stress
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What is hyperthyroidism
overactive thyroid. In general metabolic rate increases and weight loss
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Iodine deficiency (endemic goitre)
Insufficient dietry iodine. Insufficient amounts of T3 and T4. Abnormally high TSH. Abnormal growth of the thyroid due to trophic effects of TSH
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What is Hashimoto's disease
Most common cause of hypothyroidism
Autoimmune disease
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Hashimoto's disease effects
Antibodies against thyroglobulin or thyroid peroxidase
Interferes with thyroid hormone synthesis
Antibodies also against TSH receptor
Prevents stimulation of T3 and T4 release
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Congenital hypothyroidism cause
Lack of gland or incorrect hormone biosynthesis
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Congenital hypothyroidism effects
Intellectual disability. Short disproportionate body. Thick tongue and neck. Intellectual disability if treatment later than 3 months
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Hyperthyroidism symptoms
loss of weight, excessive sweating/intolerance to heat, Palpitations and an irregular heartbeat, anxiety and nervousness, exophthalmos
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Hyperthyroidism clinical exam
raised metabolic rate and oxygen consumption, increased heart rate, hypertension
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Hyperthyroidism treatment
surgical removal of all/part of thyroid gland, ingestion of radioactive iodine that selectively destroys the most active thyroid cells, drugs that interfere with the gland’s ability to make T3/T4
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Hyperthyroidism cause
Autoimmune disease -> Grave’s disease
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Graves disease symptoms
Muscle weakness, heart palpitations, irritability
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What causes grave's disease
Autoimmune B cell makes antibodies against TSH receptor that stimulate thyroid hormone production and T3/T4 release
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What charcterizes grave's disease
goitre, exophthalmos and lid retraction
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Location of adrenal glands
a pair - lie above each kidney
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Structure of adrenal glands
Each gland enclosed in a fibrous capsule surrounded by fat. Inner: adrenal medulla. Outer: Adrenal cortex – under hormone control
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What do the adrenal glands respond to
atreaa
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Adrenal development
At 7 weeks of life, the primitive adrenal medullary tissue begins to invade the cortex. At birth, the medullary cell mass is fully surrounded by the cortex. However, cortical differentiation into a zona glomerulosa, zona fasciculata, and zona reticularis is not complete until later in childhood
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How much does each adrenal gland weigh
6-10g
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Adrenal glands blood supply
Rich blood supply – adrenal arteries arise directly from the aorta. Blood flows through the cortex and drains into the medulla
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Zones of the adrenal cortex
capsule, zona glomerulosa, zona fasciculata, zona reticularis
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Which nervous system controls the adrenal medulla
sympathetic nervous system - has an enlarged and specilaized sympathetic ganglion
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What does the adrenal medulla secrete
catecholamine hormones: Adrenaline (epinephrine) and noradrenaline (norepinephrine)
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Why isn't the adrenal medulla a true endocrine gland
its not under hormonal control
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What does the adrenal medulla contain
CHROMAFFIN CELLS
SPECIALISED POSTGANGLIONIC NEURONS
Preganglionic = splanchnic nerve fibers
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What is the neurotransmitter for adrenal medulla
acetylcholine
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What does the adrenal medulla secrete
adrenaline and noradrenaline
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Cardiovascular effects of adrenaline
1. Increases Heart rate and stroke volume
2. Increase in blood pressure (systolic)
3. Vasodilation of coronary and skeletal muscle blood vessels
4. Vasoconstriction of blood vessels to ‘non-essential’ tissues (GIT, skin, kidneys)
5. Bronchodilation
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Metabolic effects of adrenaline
1. Increases the amount of energy for immediate use
2. Liver converts glycogen to glucose
3. Metabolic rate increases
4. Blood flow changes, reducing digestive system activity and urine output
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Adrenaline receptors
alpha 1, alpha2, beta 1,2,3. Adrenaline interacts primarily with beta receptors
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What is released in response to prolonged stress
mineralcorticoids and glucocorticoids
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Long-term stress response effects
Kidneys retain sodium and water. Blood volume and blood pressure rise. Proteins and fats converted to glucose or broken down for energy. Blood glucose increase immune system supressed
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What does the zona glomerulosa secrete
mineralocorticoids (Aldosterone) SALT
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What does the zona fasciculata secrete
glucocorticoids (cortisol) SUGAR
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What does the zona reticularis secrete
gondocorticoids (androgens) SEX
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What do steroid hormones initiatw
transcription of mRNA -> protein synthesis
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How is enzyme expression vairable within the zones of the adrenal cortex
the zona glomerulosa lacks 17-hydroxylase. Zona fasciculata and zona reticularis lack 18-hydroxylases
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What do high levels of circulating testosterone levels lead to
masculinization of fetal external genitalia to variable degrees
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What do adrenal glands produce
Dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione - which are testosterone and estrogen precursors
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Binding of DHEA and DHEA-S
they bind less efficiently to the androgen receptors (weak steroids) compared to testosterone.
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Where are the testosterone precursors converted into testosterone
in peripheral tissues
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Where are testosterone precursors controlled
by ACTH - anterior pituitary
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Role of testosterone in males
male secondary characteristics and aggression in young boys - adrenal glands secret little compared to testes so role not fully understood
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Adrenal androgens over/under secretion effect
no noticeable consequences
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What do females convert testosterone produced by the adrenal glands into
oestrogen
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Function of estrogen
Responsible for growth of pubic and axillary hair and sex drive
Kick start puberty
Maintain muscle and bone mass
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How much testosterone do adrenal glands secrete in females
half of the total androgenic requirement
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What can cause excess production of adrenal androgen
overproduction of ACTH, adrenal tumor, Cushing's syndrome
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symptoms of excessive adrenal androgen production
Acne, hirsutism, irregular periods, breast shrinkage…..
Play a role in polycystic ovary syndrome (PCOS)
Patients with PCOS have adrenal androgen excess
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Examples of anti androgens and what do they do
they block androgen receptors e.g., cyproterone acetate and ethinylestradiol
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Is there more or less SHEA/DHEA-S with age
less as u get older
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How is aldosterone secretion regulated
by plasma levels of sodium and potassium via the renin - angiotensin aldosterone system (RAAS)
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What does it mean when there is renin secretion
Low sodium in the distal tube
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Principle actions of aldosterone - control ECF volume
Conserve body sodium
Stimulates reabsorption of sodium in renal distal convoluted tubules in exchange for potassium
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Principle actions of aldosterone - control of release
Response to renin-angiotensin system (RAAS)
Decreased ECF volume (hypovolaemia or hypotension) and decreased renal blood flow
Response to high plasma potassium
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What can stimulate cortisol production
stress
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What is stress
physical trauma, intense heat or cold, infection, mental or emotional trauma
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What does cortisol do to mediate the body's response to stress to endocrine signals
Metabolic effects. Cortisol increases plasma glucose and FFA concentration. Provide energy substrates to body tissues for their response to the stressful event that stimulated cortisol production
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Cortisol function - increased catabolism
Cortisol increases skeletal muscle protein catabolism. Amino acids are then converted to glucose (gluconeogenesis)
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Cortisol function - increased lipolysis
Liberate free fatty acids & triglycerides from adipose tissue. Used as an energy source
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Cortisol function - increased intake
Stimulates appetite. If the stressful event doesn’t involve physical activity – weight gain. Decreased cortisol leads to weight loss and increased cortisol leads to increased apetite and weight gain
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Other actions of cortisol
1. May contribute to emotional instability
2. Anti-inflammatory – blocks the processes which lead to inflammation (in high doses)
3. Immunosuppressive – fall in antibody production and number of circulating lymphocytes
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What does ACTH do to affect production of cortisol
stimulates enzymes involved in cortisol and andorgen synthesis
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What is cushing's disease
overproduction of cortisol
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What can cause cushing's disease
adrenal or pituitary tumour
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Symptoms of cushing's disease
1. Redistribution of body fat
2. Muscle wastage
3. Thin skin, bruising abnormal pigmentation
4. Changes in CHO and protein metabolism
5. Hyperglyceamia
6. Hypertension - Cortisol has weak mineralocorticoid activity
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Cushing's syndrome treatment
surgery, radiation and medication
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What is Conn's disease
adrenal cortex hyperfunction - mineralcorticoid excess
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Effect of Conns disease
Overproduction of Aldosterone. Retention of sodium, loss of potassium and alkalosis. Hypertension through expansion of plasma volume
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What is addison's disase
adrenal cortex hypofunction
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What can cause addison's disease
Damage to adrenal glands, autoimmune disease or pituitary damage
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What does addison's disease cause
Deficits in glucocorticoids and mineralocorticoids (i.e., low cortisol, hypoaldosteronism, low sex hormone)
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Symptoms of addison's disease
Progressive weakness, lassitude and weight loss. Pigmentation of the skin and mucosal membranes
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What is calcium involved in
1. Structural component of bones and teeth (99% total calcium)
2. Maintains normal excitability of nerve and muscle cells
3. Involved in neurotransmitter and hormone release
4. Muscle contraction (skeletal and cardiac)
5. Activation of many enzymes
6. Coagulation of blood
7. Milk production
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Calcium's occurrence in nature
Does not exist freely, occurs mostly in soil systems as limestone (CaCO3), gypsum (CaSO42H2O) and fluorite (CaF2)
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Calcium's occurrence in the body
The most abundant mineral. The average adult body contains app 1kg. 0.1% in the extra cellular fluid (ECF). 1% in the cells. The rest (app. 99%) in the skeleton – hydroxyapatite. (Bones can serve as large reservoirs, releasing calcium when extracellular fluid contraction decreases and storing excess calcium).
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What us plasma calcium concentration
2.2-2.6 mM
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What are the 3 forms calcium is found in the plasma
1. protein bound calcium
2. ionized or free calcium
3. complex or chelated calcium
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Protein-bound calcium
calcium cannot diffuse through membranes and thus is not usable by tissues (41%)
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Ionized or free calcium
the physiologically active form (50%)
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Complex of chelated calcium
bound to phosphate, bicarbonate, sulfate, citrate and lactate (9%)
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What does too low calcium levels cause
involuntary muscle contraction. Neuronal hyper - excitability (tetany)
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How does low calcium levels cause involuntary muscle contraction
Low ionized calcium levels in the extracellular fluid increase the permeability of neuronal membranes to sodium ion, causing a progressive depolarization, which increases the possibility of action potentials.
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What is hypercalcemia
calcium levels are too high so neurons are less excitable (Na channels are less likely to open so harder to depolarise) and therefore slower muscle contraction
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Symptoms of hypercalcemia
slower/absent reflexes, muscle weakness, confusion, hallucination
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What are the 3 control points for calcium
1. Absorption – via intestines
2. Excretion – via kidney/urine
3. Temporary storage – via bones
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Osteoblast cell role
synthesize and secrete collagen and promote deposition of calcium phosphate (hydroxyapatite - (Ca10(PO4)6(OH)2)) crystals. Secrete factors that activate osteoclasts
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Osteoclast role
promote resorption of bone
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Osteocytes role
essential role in exchange of calcium between ECF and bone
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Acute control of calcium
Must maintain constant free Ca2+ concentration in the plasma
Mostly by rapid exchange between bone and ECF
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Chronic control of calcium
Maintain total level in the body long term
Adjust GIT absorption and urinary excretion
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What determines plasma Ca2+ concentration
1. Net absorption of Ca2+ from the GIT
2. Net excretion of Ca2+ in urine
3. Exchange of Ca2+ with bone
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What 3 hormones control plasma Ca2+ concentration
1. Parathyroid hormone
2. 1,25 – dihydroxycholecalciferol – calcitriol (activated vitamin D)
3. Calcitonin
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What secretes parathyroid hormone
the parathyroid gland (beneath the thyroid gland)
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What type of hormone is the parathyroid hormone
peptide hormone
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where is parathyroid hormone stored
within chief cells
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parathyroid hormone half life
5 minutes
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When is parathyroid hormone secreted
continuously at a kw rate but in response to loe blood calcium
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Parathyroid hormone target
bone, gut, kidney
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Parathyroid hormone function
1. Increases reabsorption of calcium from the urine. Fast acting. Decreases urinary calcium in minutes
2. Increases the expression of the enzyme 1 alpha – hydroxylase (activates vitamin D)
3. Bone: increases osteoclast activity (indirectly) causing increase in bone resorption
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Vitamin D2 (Ergocalciferol) source
plant sources
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Vitamin D3 (cholcalciferol) sources
Obtained from the diet (animal sources), food supplements and synthesized in the skin in the presence of sunlight
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What is D2 and D3 converted into
1,25 dihydroxycholecalciferol or 1,25 - (OH)2D3
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What type of hormone is vitamin D
steroid
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What regulates production of vitamin D
Liver – dietry intake
Kidney – 1 alpha hydroxylase
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1,25 – hydroxyvitamin D3 function
maintains calcium balance in the body
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How does calcitriol (1,25 dihydroxycholecalciferol) increase calcium stores
Acts on cells on the GIT to increased production of calcium transport proteins. Leads to an increase in Calcium uptake from GIT
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calcitriol (1,25 dihydroxycholecalciferol) effect on bone
Increasing rate of bone resorption – increases the secretion of osteoclast activating factors (Indirect effect)
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calcitriol (1,25 dihydroxycholecalciferol) effect on kidney
Minor effect in decreasing urinary loss of calcium
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Which enzyme converts vitamin D3/D2 into (1,25 dihydroxycholecalciferol)
1 alpha - hydroxylase
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How does calcitriol work on kidney failure patients
by increasing how much caclium we can absorb from food
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What secretes calcitonin
Secreted by the C-cells (parafollicular cells) of the thyroid gland.
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Calcitonin function
1. Lowers the level of free plasma calcium
2. Inhibition of osteoclast activity: bone resorption reduced (direct effect)
3. Increased excretion of calcium and phosphate by the kidneys
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What can calcitonin be used to treat
osteoporosis in postmenopausal women
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What increases plasma calcium
PTH and vitamin D
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Hormones involved in regulation of plasma calcium
Major hormonal regulators: PTH, 1,25 - (OH)2D3 and possibly calcitonin
Others: Growth hormone, adrenal glucocorticoids and thyroid hormones. Oestrogen and androgens
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What is hyperparathyroidism
hypercalcemia - too much vitamin D
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What is hypocalcaemia
vitamin D defficiency
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Primary hy[erparathyroidism effects
Inappropriate (autonomous) secretion of PTH, resulting in hypercalcaemia
Elevated PTH and raised serum calcium (and low serum phosphate)
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What can cause primary hyperparathyroidism
by a single parathyroid adenoma
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Presentation of primary hyperparathyroidism
bones, stones, abdominal groans and psychic moans
Increases bone resorption, increased GIT absorption, decreased renal excretion
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Presentation of primary hyperparathyroidism
painful bones, renal stones, abdominal groans and psychic moans
Increases bone resorption, increased GIT absorption, decreased renal excretion
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Vitamin D deficiency: rickets
Bone remodeling impaired
Failure of calcification
skeletal deformities of weight bearing bones in children
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Causes of a vitamin D deficiency
poor diet, malabsorption, decreased sunlight, liver or kidney disease
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What does hypocalcaemia lead to
increased excitability of nervous tissue. Pins and needles, tetany, muscle cramps, convulsions
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What does a vitamin D deficiency lead to
reduction in intestinal calcium absorption
