LEARNING OUTCOMES
•Outline the function of the adrenal glands within the endocrine
system.
Adrenal gland
-2 adrenal glands(4g)
-Each adrenal gland has 2
endocrine organs
1.adrenal cortex (80%)
2.adrenal medulla (20%)
•Describe the role of the hormones of the adrenal cortex in the body.
MINERALOCORTICOIDS FUNCTION
(aldosterone)
-aldosterone is release when Aldosterone level
Low blood pressure( less water in 1.Acts at distal & collecting Increases
ECF/blood—due LOW Na+ level) tubes of kidney
HIGH angiotensin 2
–Na+retention(transports Na+ HIGH K+ in
into (the blood/ECF) & blood/ECF/
K+elimination (transports K+ plasma
in the collecting duct or distal LOW Na+ in
convoluted tubule)during blood/ECF
urine formation
Activation renin-
–Promotion of Na+retention angiotensin
secondarily aldosterone system
-induces osmotic retention of RAAS
water &
By ACTH
-hence expands ECF volume
(adrenocorticotrphic
2.Important in long-term hormone)
regulation of blood pressure ACTH makes only a very
by the kidneys minor contribution to the
rate of aldosterone
3.Without aldosterone causes secretion even though it
hypovalaemia(less Na+ in the regulates the synthesis of
blood) intermediate steroids.
-due to loss of H2O in the RAAS activation and [K+]
blood or fall in plasma volume are much more important
-due to secreation of Na+ in Decreases
the tubule HIGH Na+
-leads to circulatory shock in
blood/ECF
GLUCOCORTICOIDS
(CORTISOL)
•Metabolic •Superimposed on this control
–Increase glucose concentration in system
blood at expense of protein & fat in
response to fasting –Diurnal rhythm & stress
•Inhibits glucose uptake by many •Act on hypothalamus to vary
tissues, sparing it for brain secretion rate of CRH
•Increases hepatic gluconeogenesis
–Important for replenishing hepatic –Diurnal rhythm
glycogen stores & maintaining normal •Plasma concentration of cortisol
blood glucose levels between meals displays a characteristic diurnal
•Stimulates protein degradation rhythm
especially in muscles Highest in morning & lowest
–Amino acids available for at night
gluconeogenesis
•Facilitates lipolysis
–Increase in free fatty acids and –Stress
glycerol •Dramatic increases in cortisol
•Permissive actions secretion occur in response to all
–Cortisol enhances the capacity of kinds of stressful situations
glucagon and catecholamines(balance
between adrenaline vs. noradrenaline)
•Stress adaptation-Most tissues
respond to cortisol
•Anti-inflammatory &
immunosuppressive effects
–If stress is accompanied by tissue
injury, inflammation and immune
responses accompany the stress
response
–Cortisol holds these responses in
check as exaggerated response could
cause harm
•Glucocorticoid therapy
–Rheumatoid arthritis & in preventing
organ transplant rejection
–Use only when warranted
•Body’s immune system suppressed
•Troublesome side-effects
(Mineralocorticoid action-blood
pressure)
•Irreversible atrophy of cortisol-
secreting cells
SEX HORMONE
(androgens&oestrogen)
•ACTH controls adrenal
• Under normalcircumstances
sex hormone secretion
adrenal sex hormones notsufficiently
abundant or powerful to induce
effects.
•Adrenal sex hormones
do NOT feedback on the
hypothalamus-pituitary-
•Dehydro-epiandrosterone(DHEA) adrenal axis
•Only adrenal sex hormone with
biological significance
–Males
•Overpowered by testosterone •DHEA inhibits
–Females gonadotropin-releasing
•Governs androgen-dependent hormone
processes
•Understand how the levels of these adrenocorticalhormones
are regulated in the body.
•Describe how alterations in the levels of the adrenocorticalhormones in the body can cause disease.
DISORDERS OF ADRENAL CORTEX
1. HYPERSECREATION
CAUSES SYMPTOMS
1.aldosterone hypersecreation
–Increased whole body
sodium, fluid volume and
Primary circulating blood volume
hyperaldosteronism/
Conn’s syndrome –Excessive K+depletion –
(HYPERSECREATING hypokalaemia
ADRENAL TUMOUR OF •Muscle weakness & fatigue
ALDOSTERONE SECRETING –High blood pressure -
CELL) hypertension
Secondary
hyperaldosteronism
(INAPPRORIATELY
ACTIVITY RASS)
2.cortisol hypersecreation
(glucocorticoids high •Adenomas of the anterior •Largely related to exaggerated
secreation) pituitary that secrete large effects of glucocorticoid
quantities of ACTH. –Excessive gluconeogenesis
–cause adrenal hyperplasia & resulting in Adrenal diabetes
excess cortisol secretion •High blood glucose –
•Referred to as Cushing’s hyperglycaemia
disease
•Glucose in urine –glucosuria
•Most common cause of
Cushing’s syndrome •Plasma protein deficiency
•Abnormal function of the –Extra glucose deposited as
hypothalamus. body fat in characteristic
–causes high levels of CRH locations.
•Abdomen, above shoulder
–then stimulates excess ACTH blades & face
release
•“Ectopic secretion” of ACTH •Appendages remain thin
by tumour elsewhere in body. because of muscle protein
–abdominal carcinoma breakdown
•Adenoma of the adrenal
cortex results in cortisol over
production.
3.Adrenal oestrogen
hypersecretion •New born females
–Infants manifest male-type
external genitalia
–Major cause of female
pseudohermaphroditism
•Adult females
–Hirsuitism
–Other male secondary sexual
characteristics
•Prepubertalmales
–Precocious pseudopuberty
•Adult males
–Overpowered by testosterone
2.INSUFFIENCY 1.Adrenocortical insuffiency
1.Primary adrenocortical Aldosterone deficiency
insuffiency/ADDISON •Addison’s Disease –Most life-threatening
DISEASE –All layers of adrenal cortex •Typically loss of adrenal
under-secreting hormones function develops slowly
–K+ retention (hyperkalaemia)
–Aldosterone & cortisol are •Reduced loss of K+in urine
deficient
•Cause •Disturbs cardiac rhythm
–Autoimmune destruction of –Na+depletion (hyponatremia)
adrenal cortex
•Excessive urinary loss of Na+
–Reduces ECF volume &
circulating blood volume &
hence lowers blood pressure
(hypotension)
Cortisol deficiency
•Poor response to stress
•Hypoglycaemia due to
reduced gluconeogenicactivity
•Hyperpigmentation –
darkening of skin
–Excessive secretion of ACTH
(Uninhibited due to low
cortisol).
–High levels of ACTH can bind
to closely related a-MSH
(melanocyte stimulating
hormone)receptors in skin &
cause darkening.
•Combined lack of
glucocorticoid &
mineralocorticoid can lead to
vascular collapse, shock &
death
2. SECONDARY
ADRENOCORTICAL •Pituitary or hypothalamus
INSUFFICIENCY abnormality
–Insufficient ACTH secretion
–Only cortisol deficient
•Appreciate the role of the hormones of the adrenal medulla in the body.
ADRENAL MEDULLA
1.consist postganglionic sympathetic neuron
2.do not haveaxonal fibres
3.releases catecholamines NORAADRENALINE
ADRENALINE----MORE ABUNDANT
•Describe how the levels of the hormones of the adrenal medulla are regulated in the body.
HORMONE FUNCTION REGULATION
1.ADRENALINE
–Together increase the rate •Controlled by sympathetic
& strength of cardiac input to adrenal gland
contraction & increases
cardiac output (SGT case,
TH increases beta
adrenergic receptor
expression-heart becomes –Injury, anger, anxiety, pain,
more adrenaline sensitive) cold, strenuous exercise &
•Raise arterial blood hypoglycaemia generate
pressure impulses in the
–Adrenaline shifts blood to preganglionic fibres.
heart & skeletal muscles
•Vasodilation of coronary &
skeletal muscle blood
vessels
–Adrenaline dilates –Upon stimulation by
respiratory airways to preganglionic fibre
reduce resistance in moving chromaffin cells release their
air in & out of lungs hormones into bloodstream
•Fusion of secretory
–Adrenaline and granules with cell membrane
noradrenaline also reduce
digestive activity and inhibit •Contents of granules are
bladder emptying extruded into interstitial fluid,
diffuse into capillaries and
into bloodstream
2,NORAADRENALINE
