Adrenal gland

Structure, hormone and functions of Adrenal gland

1. 4.3
Adrenal gland: structure, hormones and
functions in vertebrates.
Dr. Manoj K. Bangadkar

3. Adrenal gland
•The paired adrenal (suprarenal) glands, one of which lies superior to
each kidney in the peritoneal space.
•It is flattened pyramidal in shape
•In an adult, each adrenal gland is 3–5 cm in height, 2–3 cm in width, and
a little less than 1 cm thick, with a mass of 3.5–5 g.
•During embryonic
development, the
adrenal glands
differentiate into a
large, peripherally
located adrenal cortex,
and a small, centrally
located adrenal
medulla

4. Adrenal cortex:
•The adrenal cortex is divided into a outer zona glomerulosa, a
middle zona fasciculata, and inner zona reticularis
•The adrenal medulla consists of chromaffin cells and large blood
vessels.
•Cortical secretions
include
mineralocorticoids,
glucocorticoid, and
androgens.

5. •Mainly aldosterone
•Increase sodium and water
reabsorption and decrease
potassium reabsorption.
Secretion is controlled by
the renin–angiotensin–
aldosterone (RAA)
pathway and by K level in
the blood.
Mineralocorticoids

7. •Mainly cortisol
•Promote protein
breakdown,
gluconeogenesis, and
lipolysis; help resist stress;
and serve as anti-
inflammatory substances.
•Their secretion is controlled
by ACTH.
Glucocorticoids

8. •Control of glucocorticoid secretion
occurs via a typical negative
feedback system
•Glucocorticoids have the following
effects:
•Protein breakdown.
•Glucose formation
•Lipolysis.
•Resistance to stress.
•Anti-inflammatory effects.
•Depression of immune
responses

9. •The major androgen secreted
by the adrenal gland is
dehydroepiandrosterone
(DHEA)
•Androgens secreted by the
adrenal cortex stimulate
growth of axillary and pubic
hair, aid the prepubertal
growth spurt, and contribute
to libido.
Androgens

10. Adrenal Medulla
•The inner region of the adrenal gland, the adrenal medulla, is a
modified sympathetic ganglion of the autonomic nervous system
(ANS).
•Rather than releasing a neurotransmitter, the cells of the adrenal
medulla secrete hormones i.e. Epinephrin and norepinephrin

11. •In stressful situations and during exercise, impulses from the
hypothalamus stimulate sympathetic preganglionic neurons, which
in turn stimulate the chromaffin cells to secrete epinephrine and
norepinephrine.
•These two hormones greatly augment the fight-or-flight response.
•By increasing heart rate and force of contraction, epinephrine and
norepinephrine increase the output of the heart, which increases
blood pressure.
•They also increase blood flow to the heart, liver, skeletal muscles,
and adipose tissue; dilate airways to the lungs; and increase blood
levels of glucose and fatty acids.