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Functional Physiology of Adrenal Medullary
Hormones
Presented by Abdul Qahar
Subject: Endocrinology
Adrenal Glands
adrenal cortex
adrenal medulla
Adrenal Glands
• located above each kidney
• inner adrenal medulla
• outer adrenal cortex
Types of hormones-1
Amine hormones:
Hormones derived from the amino acid tyrosine.
These include epinephrine, norepinephrine and thyroid hormone.
Epinephrine and norepinephrine are produced by the adrenal medulla –water soluble
Thyroid hormone is produced by the thyroid gland –lipid soluble
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Adrenal medulla
• Part of autonomic nervous system
• Spherical chromaffin cells are modified postganglionic sympathetic neurons• Secrete epinephrine
and norepinephrine
• Amine hormones
• Fight, flight, fright
• Vesicles store the hormones
Hormones of adrenal medulla
noradrenaline 20% 1.2 - 3.4 nmol/l
• 5 - 6 fold increase exerts biological action
adrenaline 80% 0.1 - 0.8 nmol/l
• 2 fold increase can elicit physiological response
• These hormones prepare the body to deal with short- term stress.
Amine hormones: derived from tyrosine• Epinephrine, norepinephrine and dopamine
are water soluble and are synthesized and secreted like peptide hormones
• Thyroid hormones are produced by modification of a tyrosine residue contained in thyroglobulin, post-translationally modified to bind iodine, then proteolytically cleaved and released as T4 and T3. T3 and T4 then bind to thyroxin binding globulin for transport in the blood
Synthesis of catecholamines
Why are these hormones important to the maintenance of
homeostasis?
Keeps a good balance between sodium and water levels in the body. Helps with the breakdown of amino acids which maintains normal blood pressure. Acids in puberty, keeps the body alert and stimulated when necessary.
Hormones of medullary catacholamines
Epinephrine,norepinephrine and DOPA Nature – derivatives of tyrosine
Excretion is regulated by sympathetic nervous system and brain cortex
Functions:Stress hormones. Contraction of vessels, increase
the blood pressure, accelerate pulse. Contraction of uterus muscles. Epinephrine
relaxes the muscles of bronchi and intestine.On carbohydrate metabolism:
-activates the decomposition of glycogen in liver and muscles
-activates glycolysis, PPC, TAC and tissue respiration
On protein metabolism-accelerate the decomposition of proteins
On lipid metabolism-activates lipase, mobilization of lipids and their
oxidation
Figure 9.12
Hypothalamus and Adrenal Glands in Stress Response
Adrenal (Suprarenal) Glands
Lie superior to each kidney
Comprised of two parts – outer adrenal
cortex & inner adrenal medulla
Adrenal Medulla hormones
• epinephrine (adrenaline) and norepinephrine (noradrenaline) produced during times of stress
• released into blood, causes glycogen to be converted to glucose, sugar levels
• speeds up heart & breathing rates, cell metabolism, and causes pupil to dilate (more light into retina)
Figure 9.12
Hypothalamus and Adrenal Glands in Stress Response
Mechanism of
Adrenal Medulary Hormones.
Adrenal Gland
Anatomy was first described in 1563.
Is located above (or attached to) the upper pole of the kidney.
Is pyramidal in structure and weighs ~ 4 g.
Consists of the adrenal cortex and adrenal medulla
Activities are regulation of fluid volume and stress response
The General Adaptation Syndrome
Activity of Epinephrine
Mechanism: Norepinephrine Release and Recycling
Review of Efferent Pathways: Motor and Autonomic
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Adrenal medulla
• Part of autonomic nervous system
• Spherical chromaffin cells are modified postganglionic sympathetic neurons• Secrete epinephrine
and norepinephrine
• Amine hormones
• Fight, flight, fright
• Vesicles store the hormones
Catechalomines: Activity
• Stimulates the “fight or fight” reaction
• Increased plasma glucose levels
• Increased cardiovascular function
• Increased metabolic function
• Decreased gastrointestinal and genitourinary function
Identify Feedback Mechanisms and Antagonistic Hormones.
When your body is in need of epinephrine or adrenaline, hormones are secreted that release epinephrine, when there is too much epinephrine in the body then a hormones is released that stops the secretion of epinephrine.
Feedback Mechanism: A process in which the level of one substance influences the level of another substance.
Antagonistic Hormones: Hormones that act to return body conditions to within acceptable limits from opposite extremes are called.