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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.