9 calcium metabolism and HPA Flashcards by Cordelia Kuti

what are two main examples of ca2+ transporters?

ca2+ - mg2+ ATPase: high affinity, low capacity

na+ - ca2+ exchanger: low affinity, high capacity

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What can increase the risk of calcium deficiency ?

lactose free diet
coeliac disease
osteoporosis
breastfeeding
menopausal females

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organs involved in calcium deficiency?

Gut
bone
kidneys

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bone is made of ? bound to a proteoglycan matrix

calcium hydroxyapatite

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Action of PTH on bone?

intermediate action

binds to osteoblasts - inhibits bone formation and release cytokines (chemical messenger)

cytokines stimulate osteoclasts - increase bone resorption/breakdown and release Ca2+ and phosphate.

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action of PTH on kidneys?

stimulates reabsorption of filtered Ca2+

increased loss of phosphate in urine

activates calcitriol (from Vit D) - uptake of Ca2+ from gut

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how does absorption of Ca2+ occur?

dependent on Vit D (converted by liver/kidney to active form calcitriol)

D3 - from sunlight (7, dehydroxycholesterol)
D3 - from diet (25-hydroxyvitamin )

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cells that secrete PTH?

chief cells

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PTH initiates what response to low calcium ions?

Mobilization of calcium from bone.

Enhancing absorption of calcium from the small intestine.

Suppression of calcium loss in urine.

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What is PTHrp?

a hormone - PTH-related peptide; that acts at PTH receptors.

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hypercalcemia causes and symptoms

increase in serum calcium levels

causes- hyperthyroidism, renal failure, drug induced

symptoms - kidney stones, stomach pain, nausea, easy fractures

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hypocalcemia causes and symptoms

decrease in serum calcium levels

causes - hypothyroidism, GI malabsorption, renal loss

symptoms - impaired cognition, twitching, seizures

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Calcitonin opposes the action of which hormones

Parathyroid
Calcitriol

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How does Calcitonin reduce ECF calcium levels

Inhibit osteoclast
Decrease kidney resorption

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How is calcium lost from the body

Urine
Faeces

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How is intracellular calcium controlled

Pumped out of cells
Sequestered into organelles(Sarcoplasmic reticulum and mitochondria)

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How much calcium in extracellular fluid

2.1mmol/l

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What are some roles of calcium (4)

Lower blood pressure
Regulate heart rhythm
Importance in intracellular signal pathway
Assists in Normal blood clotting

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What are the 3 categories of hypercalcaemia causes

Hormonal
Non hormonal
Drugs

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What are the 3 principle cells in the Parathyroid

Chief cells
Oxyphil cells
Adipose cells

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What are the causes of hypocalcaemia

Hypoparathyroidism
Hypovitaminosis D
GI malabsorption

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what are the CNS effects of hypocalcaemia

irritability
seizures
personality changes

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What are the general effects of hypercalcaemia

Stones(kidney stones )
Moans (depression)
Groans(abdominal pain)

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What are the hormonal causes of hypercalcaemia

Primary hyperparathyroidism
Hypervitaminosis

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What are the main hormone regulators of calcium

Parathyroid Vitamin D Calcitonin

what are the neuromuscular effects of hypocalcaemia

tetany parestesia twitching convulsions

What are the non hormonal causes of hypercalcaemia

Renal failure

What calcium is physiologically active

Free ionised calcium

What can be used in managing a deficiency or excess in pituitary hormone secretion

hormonal therapy medical therapy

What can lead to a calcium imbalance

Poor absorption Poor calcium intake Excessive loss-lactation

What does hypervitaminosis D cause

Excessive production of 1,25 dihydroxy vitamin D3 Suppression of PTH

What drugs can cause hypercalcaemia

Thiazides Lithium

What feedback system in parathyroid hormone

negative

What gland is parathyroid hormone released from

parathyroid gland

What inhibits parathyroid release

High extracellular calcium

What is 25 hydroxy vitamin D3 converted to in the liver

1,25-dihydroxy vitamin D3

What is 7-dehydrocholesterol converted to in the skin

Cholecalciferol

What is calcitonin secreted from

Parafollicular cells of the thyroid gland

What is cholecalciferol converted to in liver

25-hydroxy vitamin D3

what is humoral hypercalcaemia of malignancy

tumour secretion of parathyroid hormone-related peptide [PTHrP]

What is hypercalcaemia

Calcium levels rises

What is hypocalcaemia

Calcium levels fall

What is the action of calcitriol on the bone

Stimulate bone re-modelling

What is the action of Parathyroid on the bone

Bind to osteoblasts Inhibit bone formation Release cytokines which stimulate osteoclasts Increased bone breakdown Release of calcium and phosphate

What is the action of parathyroid on the kidneys

Stimulate increased reabsorption of calcium Increased loss of phosphate in urine Activation of calcitriol

What is the action of parathyroid on the kidneys

Stimulate increased reabsorption of calcium Increased loss of phosphate in urine Activation of calcitriol

What is the normal response to hypercalcaemia

Decreased Parathyroid Decreased calcitriol -less calcium taken up from gut Less calcium absorption from kidney Decreased breakdown of bone Increase bone formation

What is the normal response to hypocalcaemia

Increased parathyroid production Increased calcitriol Increased calcium absorption from gut and kidney Increased breakdown of bone Decreased bone formation

What is the process for negative feedback control for parathyroid

Decreased calcium stimulate parathyroid Parathyroid acts on bone and released calcium and raises calcium concentration Increased calcium inhibits parathyroid release

What is the role of calcitriol in the gut

Increased expression of proteins that import Ca2+ Promote absorption of calcium from diet

What is the role of PTHrP

Cartilage development Calcium transport in placenta

What is the role of the chief cells

Produce and degrade parathyroid

What occurs as a result of Parathyroid suppression

Decreased bone resorption Increased urinary loss of calcium Decreased 1,25-dihydroxy Vitamin D3 production

what organ systems affected by hypocalcaemia

Neuromuscular CNS Cardiovascular

What organ systems are effected by hypercalcaemia(5)

CNS GI Renal Skeletal Cardiovascular

What stimulate the synthesis and secretion of parathyroid

Low extracellular calcium

By what method is PTHrP released

Paracrine

How are lactotropes controlled

Hypothalamus secrete dopamine dopamine inhibit prolactin secretion lactotropes release increased due to prolactin reduction

How are neurones that secrete hypothalamic releasing hormones affected

nervous inputs - enviroment influences endocrine system chemical signals-feedback

how does hypothalamus control anterior pituitary secretion

release neurohormones from median eminence which travels in hypophyseal portal circulation to anterior pituitary gland

How is Gonadotropin Releasing Hormone (GnRH) released

small pulses

how is the hypothalamus and anterior lobe of pituitary gland connected

vascular connection

how is the hypothalamus and posterior lobe of pituitary gland connected

neurological connection

how is the pituitary gland developed

anterior lobe formed from ectodermal cells from roof of pharynx fusion of anterior lobe with down growth neural tissue from hypothalamus

what are gonadotropes controlled by

Gonadotropin Releasing Hormone (GnRH)

what are somatotropes controlled by

Growth Hormone Releasing Hormone (GHRH)

what are the effects of Adrenocorticotropic hormone deficiency

mild hypotension hyponatraemia (low level of sodium in blood)

What are the effects of gonadal deficiencies

loss of libido loss of secondary sexual hairs erectile dysfunction

What are the effects of Growth hormone deficiency

growth failure in children impaired wellbeing in adults

What are the effects of hyperparathyroidism

Hypercalcuria Increased risk of fracture Increase risk of kidney stones

what are the effects of Thyroid stimulating hormone deficiency

weight gain dry skin cold intolerance

What can cause hypoparathyroidism

Post surgery Autoimmune Pseudohypoparathyroidism( PTH resistance)

what cell produces adrenocorticotropic hormone

corticotropes

what cells are most abundant in the anterior pituitary

somatotropes

what cells produce thyroid stimulating hormone

thyrotropes

what condition associated with excess Adrenocorticotropic hormone

cushing's disease

what conditions are associated with excess growth hormone

Acromegaly gigantism

what controls thyrotropes

Thyrotropin Releasing Hormone (TRH)

what do Follice stimulating hormone and luteinising hormone act on

gonads to control reproduction

what does anterior pituitary arise from

Rathke's pouch

what does anterior pituitary secreate

tropic hormones

What does Gonadotropin Releasing Hormone (GnRH) stimulate

Luteinising and follice stimulating hormone secretion

what does posterior pituitary arise from

neuroectoderm

what does prolactin do

controls milk production and reproductive processes

what is follice stimulating hormone produced by

gonadotropes

what is growth hormone produced by

somatotropes

What is hypopituitarism

decreased secretion of one or more pituitary hormones

what is luteinising hormone produced by

gonadotropes

what is prolactin produced by

lactotropes

What is pseudohypoparathyroidism

Parathyroid resistance

what is pituitary adenomas

growth or tumor on the pituitary excess hormonal secretion

what is the management for pituitary tumours

Surgery radiotherapy medical therapy

what is the most common cause of pituitary disease

pituitary adenomas

what is the role of the infundibulum

connection between the hypothalamus and the posterior pituitary.

What type of gland is anterior pituitary

endocrine

what type of gland is posterior pituitary

neurosecretory gland

Where is the parathyroid gland located

4 glands around the thyroid gland

base of brain in sella turcica

Why does parathyroid increase loss of phosphate in urine

Since calcium is being absorbed phosphate needs to be removed or it will react with calcium and form calcium hydroxyapatite

9 calcium metabolism and HPA Flashcards

(99 cards)