Endocrine Physiology 4 Flashcards
Adrenal glands are situated where
Superior pole of kidney in retroperitoneal space
Adrenal Medulla makes up what percentage of adrenal gland
25%
Adrenal medulla is what type of gland
neuroendocrine
Adrenal Medulla secretes what from postganglionic cell
Catecholamines (Epinephrine (adrenaline), norepinephrine and dopamine
Adrenal cortex secretes
Mineralcorticoids eg Aldosterone
Glucortocioids
Sex Steroids
aldosterone is involved in regulation of
na+ AND K
which hormones are essential for survival
aldosterone and cortisol
zona glomerulosa produces
aldosterone
zona fasiculata produces
glucorticoids
zona reticularis produces
sex hormones
Defects in 21 Hydroxylase common cause of
congenital adrenal hyperplasia = deficiency in aldosterone and cortisol
Lack of 21 Hydroxylase inhibits
synthesis of cortisol
95% of plasma cortisol is bound to
carrier protein
All nucleated cells have
cytoplasmic glucorticoid receptors
Peak of cortisol release
6-9am
Cortisol has a what type of action on glucagon
permissive
Cortisol does what to Gluconeogenesis
Stimulates
Cortisol does what in Proteolysis
stimulates breakdown of muscle protein
Cortisol does what in lipolysis
stimulates lipolysis in adipose tissue increasing FFA plasma
cortisol does what to insulin sensitivity
decrease
excess cortisol is said to be
diabetogenic
Cortisol does what to Ca2+ Balance (3)
Decrease Absorption from Gut
Increase Excretion at Kidney
Increase Bone Resorption = Osteoporosis
Cortisol does what to Norepinephrine
Permissive
Low levels of cortisol associated with
hypotension
Cortisol does what to immune system
Suppresses
Cortisol does what in muscle
Protein Catabolism
What is the risk of withdrawing chronic glucocorticoid treatment
Risk of adrenal insufficiency
What does aldosterone do to Na+ and K+ (3)
Increases reabsorption of Na+
Promotes excretion of K+
Increases Blood Vol and BP
1 Degrees Hypercortisolim is related to which condition
Cushings Syndrome
2 Degrees hypercortisolism is related to which condition
Cushings Disease
Cortisol is said to be what in Cushings eg Anabolic or catabolic
Catabolic
CRH and ACTH release promoted by
Stress
which three factors disinhibit HPA
Alcohol
Caffeine
Lack of Sleep
Phaeochromocytoma found in
Adrenal Medulla results in excess Catecholamines
Phaeocromocytoma said to be
Diabetogenic due to adrenergic effect on glucose metabolism
5 Roles of Calcium in Body
Signalling Clotting Apoptosis skeletal Strength Membrane Excitability
Ca2+ does what to Na+ permeability
Decreases
What factor of calcium is most critical in short term homeostasis
Ca2+ decreases Na+ permeability
Hypocalcaemia does what to neuronal na+ permeability
increases leading to hyper excitation of neurons
hypercalcaemia does what to neuronal na+ permeability
decreases neuronal na+ permeability reducing excitability
Calcium distribution in Bones
99%
Calcium distribution intracellular
0.9% in Mitochondria and SR
Calcium distribution Extracellular
0.1% (Cytosol)
How much calcium in body free in solution and physiologically active
0.05%
Calcium stored in bone in form of
Hydroxyapatite (Ca10, Po4)
How much calcium in plasma
2.2-2.6mm (0.1%)
Calcium affinity for proteins
Very high
40% bound to plasma proteins
Calcium in plasma is
2.4mm
Free Ionised
Physiologically Active
Actually 1.2mm
10% of Plasma Calcium Ions bind to
plasma anions
Calcium distribution in blood protein bound
albumin 80%
globulin 20%
calcium distribution free ionised in blood
50% and physiologically active
calcium distribution complexed in blood
10%
Binding capacity for plasma proteins and ca2+ increases under
alkalotic conditions eg hyperventilate than plasma ph rises
what happens in acidosis with binding capacity for ca2+
reduces and free ca2+ plasma rises
Total body calcium is determined by
total body calcium = calcium in-calcium out
Osteoblasts are
bone building
Osteoclasts
mobilise bone
Secrete H+
Which two key hormones act to increase Ca2+ plasma
Parathyroid Hormone: polypeptide hormone
Calcitiriol produced from vit d by liver and kidneys
which hormone acts to decrease ca2+ plasma
Calcitonin
- Peptide hormone
- released from parafollicular clear cells of thyroid gland
PTH is released in response to
decrease in free ca2+ plasma
PTH acts to increase free Ca2+ plasma by (5)
- Stim osteoclasts to increase resorption of Ca2+ and phosphate in bone
- Inhibit osteoblasts = reduce Ca2+ deposition in bone
- Increase reabsorption of Ca2+ from kidney tubules = decrease excretion in urine
- Increase renal excretion of phosphate = increase Ca2+
- Stimulate kidney to synthesise calcitriol from Vit d which promotes calcium absorption at gut and kidney
What is the active form of Vit D3 or 1.25 Dihydroxycholecalciferol
Calcitriol
Calcitirol is a
Steroid Hormone derived from cholesterol
Calcitriol is produced by
Inactive Vit D (Cholecalciferol) found in diet or skin
Enhanced by Prolactin
Calcitriol binds to nuclear receptors in intestine, bone and kidney to (3)
increase absorption of Ca2+ from gut
facilitate renal absorption of Ca2+
mobilise calcium stores in bone by stem osteoclast activity
Prolactin does what to Calcitriol synthesis
Stimulates
How much dietary Ca2+ is absorbed in healthy individual
30%
In Vit D Deficiency what happens to levels
Fall to less than 20
What conditions can happen with Vit D deficiency
Rickets
osteomalacia
Which hormone acts to decrease Ca2+ plasma
Calcitonin
- Peptide
- Produced by Thyroid Gland
- Secretion stim by increase Ca2+
- Binds to osteoclasts and inhibits bone resorption and increases Renal excretion
What does cortisol do to osteoblasts
inhibits
What to cortisol do to Calcium
Increases renal excretion
Reduces intestinal absorption of Ca2+
= Increases Bone resorption
Osteogren does what to bone formation
Promotes
Prolactin does what to calcium absorption
Promotes
