The document discusses the adrenal glands and their hormones. It describes that the adrenal glands are divided into the outer cortex and inner medulla. The cortex secretes steroid hormones like cortisol and aldosterone. Cortisol regulates carbohydrate, protein, and fat metabolism. Aldosterone regulates sodium and potassium levels. The medulla secretes catecholamines like epinephrine and norepinephrine which increase heart rate and mobilize energy stores. The hormones act through complex feedback mechanisms and play important roles in the stress response.
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6.Adrenal galnds.ppt
1. Hormones of the Adrenal Glands
31-May-23 Adrenal Medulla Hormones 1
2. Adrenal Glands
⢠Suprarenal glands
⢠Divided into
â outer Cortex and inner Medulla
31-May-23 Adrenal Medulla Hormones 2
3. Adrenal Glands
⢠Suprarenal glands weigh 5 gm
⢠Divided into outer Cortex (80% of gland)
and inner Medulla (20% of gland)
⢠Despite their organization
â into a single gland, the medulla and cortex
are functionally different endocrine organs,
and have different embryological origins.
⢠The medulla
â is derived from ectoderm (neural crest),
â while the cortex develops from mesoderm.
31-May-23 Adrenal Medulla Hormones 3
5. Adrenal Medulla
⢠Cells in the adrenal medulla
â synthesize and secrete catecholamine
⢠norepinephrine, epinephrine & dopamine
â also small amount of opioid peptides
⢠met-enkephalin, leu-enkephalin
⢠Roughly 80% of the catecholamine output
is epinephrine
31-May-23 Adrenal Medulla Hormones 5
6. Adrenal Medulla
ďˇ In adrenal medulla
ďˇ The chromaffin cell is the principle
cell type.
ďˇ There are epinephrine releasing
chromaffin cells and norepinephrine
releasing cells
31-May-23 Adrenal Medulla Hormones 6
7. Adrenal Medulla
⢠80% of chromaffin cells
â secrete adrenalin
â 20% secrete nor adrenalin
ďˇ The medulla is richly
innervated
ďˇ by preganglionic sympathetic
fibers
ďˇ and is, in essence, an extension
of the sympathetic nervous
system.
31-May-23 Adrenal Medulla Hormones 7
8. Adrenal Medulla
⢠The chromaffin cells
â are like the post
ganglionic cells
â in the sympathetic
nervous system
⢠The pre-ganglionic
fibres
â Originate from T5 â T9
31-May-23 Adrenal Medulla Hormones 8
T5 â T9
Symp pre-
ganglionic
nerve
Chromaffin
cells
Adrenalin
Noradrenalin
9. Adrenal Medulla
⢠These preganglionic
fibres
â release acetylcholine
as the
neurotransmitter
⢠Ach cause the
chromaffin cells to
release
â Adrenalin
â Nor-adrenalin
31-May-23 Adrenal Medulla Hormones 9
T5 â T9
Symp pre-
ganglionic
nerve
Chromaffin
cells
Adrenalin
Noradrenalin
Ach
10. Adrenal Medulla
⢠Adrenalin
â Mainly produced in adrenal medulla
â Small amount is secreted in brain
⢠Nor adrenalin
â Widely distributed in neural tissues
including
⢠Adrenal medulla
⢠Sympathetic postganglionic fibers
⢠CNS
31-May-23 Adrenal Medulla Hormones 10
12. Control of Secretion
⢠Secretion of catecholamine
â by chromaffin cells is stimulated by
⢠Acetylcholine
⢠Angiotensin II
⢠Histamine
⢠Bradykinin
31-May-23 Adrenal Medulla Hormones 12
13. Control of Secretion
⢠Stress
â Flight or fight reaction
â Activation of sympathetic system
⢠Fear, anxiety, pain, trauma,
hemorrhage
⢠Any stressful situation
â Lead to release of catecholamines
31-May-23 Adrenal Medulla Hormones 13
14. Physiological Actions
⢠In general,
â circulating
epinephrine&norepinephrine
â released from the adrenal medulla
â have the same effects on target
organs as direct stimulation by
sympathetic nerves.
31-May-23 Adrenal Medulla Hormones 14
15. Physiological Actions
⢠Complex physiologic responses
â result from adrenal medullary
stimulation
â because there are multiple
receptor types
â which are differentially expressed
â in different tissues and cells
31-May-23 Adrenal Medulla Hormones 15
16. Physiological Actions
⢠Effects depend on the type of
receptors on target organ
âďĄ receptors or ď˘ receptors
⢠Adrenaline act on both ďĄ and ď˘
receptors
⢠Nor adrenaline act mainly on ďĄ
receptors
31-May-23 Adrenal Medulla Hormones 16
17. Physiological Actions
â˘ ďĄ Adrenergic receptors
â Associated with excitatory function of
the body
â Associated with inhibitory functions of
intestinal motility
â˘ ď˘ Adrenergic receptors
â Associated with most of inhibitory
functions of the body
⢠Except on the myocardium
âExcitation
⢠31-May-23 Adrenal Medulla Hormones 17
18. Physiological Actions
⢠Effects on the heart
âNor-adrenalin & adrenalin both
increase the
⢠Heart rate, force of
contraction (ď˘1 receptors)
âIncrease effectiveness of the
heart
⢠Myocardial excitability
31-May-23 Adrenal Medulla Hormones 18
22. Hormones of the Adrenal cortex
31-May-23 Adrenocortical Hormones 22
23. Adrenal Cortex
⢠Synthesize and secrete
â steroid hormones (corticosteroids)
⢠Synthesize from steroid
cholesterol
⢠Have nearly similar chemical formula
⢠Slight differences in molecular
structure give them different
functions
31-May-23 Adrenocortical Hormones 23
24. Corticosteroids
⢠Three groups of corticosteroids
⢠Mineralocorticoids
â Effect on electrolytes
⢠Glucocorticoids
â Exhibit important effect in
increasing blood glucose
concentration
â Also affect fat, protein metabolism
⢠Androgens
â Sex hormones
31-May-23 Adrenocortical Hormones 24
25. Adrenal Cortex
⢠Histologic
examination
â of the cortex
reveals
â three concentric
zones of cells
â that differ in the
major steroid
hormones
â they secrete
31-May-23 Adrenocortical Hormones 25
Glomerulosa
Fasciculata
Reticularis
Medulla
27. Adrenal Cortex
⢠Zona fasciculata
â middle layer of
cortex
⢠Zona reticularis
â Innermost layer of
cortex
⢠Zona fasciculata &
reticularis
â Secrete cortisol &
androgens
31-May-23 Adrenocortical Hormones 27
Glomerulosa
Fasciculata
Reticularis
Medulla
28. Structure of steroid hormones
⢠All steroids
â have the same
basic
cyclopentanoperh
ydrophenanthrene
ring structure
⢠Have
â 3 cyclohexyl rings
⢠( A, B, C)
â One cyclopentyl
ring (D)
31-May-23 Adrenocortical Hormones 28
19
3
2
1
8
7
6
5
4
10
9
15
14
13
12
11
18
17
16
A B
C D
Cyclopentanoperhydrophenanthrene
30. Transport & Fate of Adrenal
Hormones
⢠Cortisol
â Combine with Cortisol binding
globulin (CBG)
⢠Transcortin
⢠Also can combine with
albumin
⢠About 94% transported in
bound form; 6% in free form
31-May-23 Adrenocortical Hormones 30
31. Transport & Fate of Adrenal
Hormones
⢠Aldosterone
âCombine loosely with plasma
protein
âAbout 50% is in free form
⢠Both combined and free forms
âare transported through out ECF
31-May-23 Adrenocortical Hormones 31
32. Transport & Fate of Adrenal
Hormones
⢠Adrenal steroids degraded in liver
⢠Conjugated to glucoronides or
sulfated to sulfate
â Then 25% excreted though bile
â 75% excreted through urine
⢠Hence diseases of liver
â Greatly affect hormone degradation
31-May-23 Adrenocortical Hormones 32
34. Functions of Glucocorticoids
⢠Affect metabolic systems for
utilizing
â Carbohydrates
â Proteins
â Fats
⢠95% of glucocorticoid activity
â of adrenal cortex
â result from Cortisol
31-May-23 Adrenocortical Hormones 34
35. Mechanism of Action
⢠Multiple effects
â of glucocorticoids
â triggered by
â binding to
intracellular
receptors
â which interact with
specific regulatory
DNA sequences
⢠Glucocorticoids
Response Element
31-May-23 Adrenocortical Hormones 35
36. Mechanism of Action
⢠Induce or repress
â gene transcription
⢠Leads to increased
or decreased
â formation of mRNA
⢠Alters synthesis of
enzymes
⢠Alter cell
functions
31-May-23 Adrenocortical Hormones 36
37. Effects of Cortisol on carbohydrate
metabolism
⢠Stimulate gluconeogenesis
âď liver enzymes for converting
AA into glucose
â˘ ďŻ glucose utilization by cells
â Exert anti insulin effect
⢠Block glucose transport in muscle
& adipose tissue
⢠Cortisol indirectly inhibit activity of
glycolytic enzymes
⢠Glucokinase, phosphofructokinase,
pyruvate kinase
31-May-23 Adrenocortical Hormones 37
38. Effects of Cortisol on Protein
Metabolism
⢠Glucocorticoids enhance protein
catabolism in skeletal muscle, and
other extra hepatic tissues
⢠Released AA are transported to
liver where are converted to glucose
⢠Glucocorticoids inhibit protein
synthesis
31-May-23 Adrenocortical Hormones 38
39. Effects of Cortisol on Fat
Metabolism
⢠Glucocorticoids are lipolytic
â Potentiate lipolytic actions of
other hormones
⢠GH, catecholamines, glucagon,
T3,T4
â Favour FA mobilization
⢠from adipose tissue to liver
31-May-23 Adrenocortical Hormones 39
40. Fat Metabolism
⢠FFA metabolized by liver
â ď˘-Oxidation
⢠formation of ketone bodies
â Inhibit glycolysis
⢠Fructose 1,6 diphosphatase
â Activated by FA
⢠Pyruvate kinase ,
phosphofructokinase
â Inhibited by FA
⢠Glycolysis is inhibited,
gluconeogenesis proceeds
31-May-23 Adrenocortical Hormones 40
41. Fat Metabolism
⢠Glucocorticoids indirectly
stimulate lipolysis by
â Blocking peripheral glucose
uptake, utilization
â Inhibit re-esterification of FA in
adipose tissue
⢠Inhibit the use of glucose
31-May-23 Adrenocortical Hormones 41
42. Effects of Cortisol on Fat
Metabolism
⢠Cortisol inhibit FA synthesis in the
liver
â This effect is not observed in adipose
tissue
⢠Overall effect
â Redistribution of body fat
â ď In total body fat
⢠Truncal obesity
31-May-23 Adrenocortical Hormones 42
43. Effects of Cortisol on Fat
Metabolism
⢠Characteristic centripetal
distribution of fat
â Accumulation of fat on central
axis of body
â Deposition of fat on the face
⢠Moon face
31-May-23 Adrenocortical Hormones 43
44. Effects of Cortisol on Fat Metabolism
⢠Deposition of fat in supra
scapular region
⢠Buffalo hump
â Excessive fat distribution
⢠Pendulous abdomen
31-May-23 Adrenocortical Hormones 44
45. Anti-inflammatory and
immunosuppressive effects
⢠The anti-inflammatory and
immunosuppressive effects
â of glucocorticoids are largely secondary
to their inhibition of the immune responses
⢠of lymphocytes, macrophages, and
fibroblasts.
⢠Also by stabilizing the lysosomes
â of damaged cells
â preventing the release of the mediators of
inflammation
31-May-23 Adrenocortical Hormones 45
46. anti-inflammatory and
immunosuppressive effects
⢠Whereas NSAIDs principally
â inhibit prostaglandin synthesis,
â corticosteroids interfere earlier
â in the inflammatory cascade
â by inhibiting PLA2 actions
â and thereby curtailing
⢠both the leukotriene and
prostaglandin mediated inflammatory
response
31-May-23 Adrenocortical Hormones 46
47. anti-inflammatory and
immunosuppressive effects
⢠increased levels of
glucocorticoids
â serve to suppress the immune
system.
⢠This is achieved by decreasing
â the production of lymphocytes
(especially T cells) and antibodies
â Also reduce number of eosinophils
31-May-23 Adrenocortical Hormones 47
48. Control of Secretion
⢠Hypothalamus
â under the influence of
higher centers
â Releases Corticotrophin
releasing hormone
(CRH)
31-May-23 Adrenocortical Hormones 48
Limbic system
CRH
Hypotha
lamus
ACTH
Adeno-
hypophysis
Plasma
cortisol
conc
Adrenal
cortex
Negative
feed back
49. Control of Secretion
⢠CRH acts on
anterior pituitary
â Releases ACTH
⢠ACTH acts on
adrenal cortex (zona
fasciculata)
â Releases cortisol
â Released into plasma
31-May-23 Adrenocortical Hormones 49
Limbic system
CRH
Hypotha
lamus
ACTH
Adeno-
hypophysis
Plasma
cortisol
conc
Adrenal
corte
Negative
feed back
50. Control of Secretion
⢠Conc of plasma
cortisol
â Negative feedback
inhibition
⢠Hypothalamus
⢠Anterior pituitary
31-May-23 Adrenocortical Hormones 50
Limbic system
CRH
Hypotha
lamus
ACTH
Adeno-
hypophysis
Plasma
cortisol
conc
Adrenal
corte
Negative
feed back
54. Aldosterone
⢠Secreted by the cells
â of the zona glomerulosa
⢠Functions
âIncrease Na+ re-absorption by
⢠the kidneys, sweat glands,
salivary glands, GIT
âIncrease excretion of K+, H+
31-May-23 Adrenocortical Hormones 54
55. Mechanism of Action
⢠Site of action
âAct on the
Principal cells
âof the late
distal
tubules&Cortic
al collecting
duct
31-May-23 Adrenocortical Hormones 55
Na+
Na+
K+
Lumen
ISF
Na+
56. Mechanism of Action
⢠Thus Aldosterone
â Increase the
number of Na-K
ATPase molecules
in the basal lateral
membrane
⢠Aldosterone increase
the exchange of
sodium and
potassium
â Na+ conservation in
ECF
â K+ is excreted
31-May-23 Adrenocortical Hormones 56
Na+
Na+
K+
Lumen
ISF
Na+
57. Control of Aldosterone Secretion
⢠ECF volume/Blood volume
⢠Arterial BP
⢠ď K+ conc in ECF leads to an ď
in aldosterone secretion
⢠ď Na+ conc in ECF inhibits
aldosterone secretion
31-May-23 Adrenocortical Hormones 57
58. Atrial Natriuretic Peptide (ANP)
⢠ANP inhibit production of
âRenin
âAldosterone
⢠Leads to a reduction of Na+ by
the nephrons and hence
âIncreased Na+ excretion in urine
31-May-23 Adrenocortical Hormones 58