Difference Between Adrenal Medulla and Adrenal Cortex (With Table)

A human body has two adrenal glands that are attached to the top of each kidney. These glands are responsible for secreting hormones into the bloodstream. The process is very crucial for a healthy life. The adrenal medulla and adrenal cortex are two distinct zones of the adrenal gland that produce different hormones.

Adrenal Medulla vs Adrenal Cortex

The difference between adrenal medulla and adrenal cortex is that the adrenal medulla is the central part of the adrenal gland whereas the adrenal cortex is the outer layer that covers the entire medulla. The adrenal medulla makes up about 25% of the adrenal gland whereas the adrenal cortex makes up 75% of it.  

The adrenal medulla is the soft innermost part that makes up 25% of the adrenal gland. It is responsible for the secretion of hormones including adrenaline, noradrenaline, and a small amount of dopamine. These chemicals are involved in sending nerve signals to different parts of the body. The adrenal medulla is made up of chromaffin cells that are grouped around blood vessels.

The adrenal cortex is the firm outermost part that makes up 75% of the adrenal gland. The region is divided into three zones namely zona glomerulosa, zona reticularis and zona fasciculata. Each of these produces different kinds of hormones that further carry out different processes in the body. Moreover, androgen synthesis takes place in this region as well.

Comparison Table Between Adrenal Medulla and Adrenal Cortex

Parameters of ComparisonAdrenal MedullaAdrenal Cortex
RegionThe adrenal medulla is the central or innermost part of the adrenal gland.The adrenal cortex is the outermost layer of the adrenal gland.
ConstitutionIt constitutes 25 per cent of the adrenal gland.It constitutes 75 per cent of the adrenal gland.
QualityIt is soft.It is firm.
DevelopmentIt develops or originates from the ectoderm.It develops from the mesoderm.
EnclosureIt is not enclosed by any kind of fibrous capsule.It is enclosed by a fibrous capsule.
DivisionIt is not divided into zones.It is divided into 3 zones.
Major HormonesThe major hormones released by the adrenal medulla include adrenaline and noradrenaline.The major hormones released by the adrenal cortex include aldosterone, cortisol, and androgens.
ImportanceThe adrenal medulla is not essential for life and its destruction does not cause death.The adrenal cortex is essential for life and its destruction may prove to be fatal.

What is Adrenal Medulla?

The adrenal medulla is the soft region situated at the centre of the adrenal gland. It comprises chromaffin cells that are responsible for the secretion of hormones. These include adrenaline, noradrenaline, and a small amount of dopamine. The cells are also connected with the sympathetic division of the nervous system. They release chemicals when the sympathetic preganglionic neurons stimulate them.

The adrenal medulla causes changes in a person’s energy availability, heart rate and even basal metabolic rate. It even increases blood glucose levels by supplying glucose along with oxygen to the brain and muscles. Noradrenaline, which is produced in this region, constricts blood vessels which leads to an increase in a person’s blood pressure. However, the adrenal medulla is not essential for life and its destruction is not fatal.

Adrenaline is an important chemical that the adrenal medulla produces. Ever had the feeling of panic and anxiety on being scared? The sudden tingle and rush are all part of ‘fight-or-flight’ symptoms. These occur when the adrenal medulla releases adrenaline suddenly in scary situations. However, other chemicals produced in the adrenal medulla help the body cope with this physical and emotional stress. Moreover, the adrenal medulla also produces dopamine which is a ‘feel good’ chemical. It interacts with the reward centre of the brain and affects a person’s mood, movement, memory and even focus.

What is Adrenal Cortex?

The adrenal cortex is the firm region of the adrenal gland that covers the entire adrenal medulla. It is the outermost layer that makes up 75% part of the gland. It is created in the mesoderm and is enclosed by a fibrous capsule. The region is responsible for the secretion of major hormones including aldosterone, cortisol, and androgens.

Aldosterone is the hormone that is responsible for controlling sodium and potassium levels in the blood. While sodium is an electrolyte that controls the bloodstream, potassium is responsible for regulating blood pressure. It performs this function by sending signals to the kidney to absorb sodium from the blood and release potassium into the urine.

Another important hormone produced in the adrenal cortex is cortisol. This chemical regulates blood pressure, decreases bone formation, increases blood sugar, and reduces inflammation. It is the hormone that makes use of fats, carbohydrates, and proteins in the body. It also controls the rhythm of a persons circadian. When a person undergoes stressful situations, this is the hormone that helps to increase the energy level and cope with stress.

The adrenal cortex is an essential region that carries out several body processes. If any kind of harm or destruction is caused, it may even lead to the death of the person.

Main Differences Between Adrenal Medulla and Adrenal Cortex

  1. The adrenal medulla is the innermost part of the adrenal gland whereas adrenal cortex is the outermost layer that covers the adrenal medulla.
  2. The adrenal medulla constitutes 25 per cent of the adrenal gland whereas the adrenal cortex constitutes 75 per cent of it.
  3. The adrenal medulla is soft whereas the adrenal cortex is firm.
  4. The adrenal medulla originates from the ectoderm whereas the adrenal cortex originates from the mesoderm.
  5. The adrenal medulla is not enclosed by a fibrous capsule whereas the adrenal cortex is enclosed by a fibrous capsule.
  6. The adrenal medulla is not divided into any zones whereas the adrenal cortex is divided into three zones.
  7. The major hormones released by the adrenal medulla are adrenaline and noradrenaline whereas those released by the adrenal cortex are aldosterone, cortisol, and androgens.
  8. The adrenal medulla is not essential for life whereas the adrenal cortex is essential, and its destruction may lead to death.

Conclusion

The adrenal medulla and adrenal cortex are two regions of the adrenal gland that secrete various hormones. The adrenal medulla is the central innermost layer whereas the adrenal cortex is the outermost layer that covers the entire medulla. While the medulla constitutes 25 per cent of the adrenal gland, the cortex constitutes 75 per cent of it.

A major difference between the two regions is that they produce different hormones that perform different functions in the body. The adrenal medulla releases adrenaline and noradrenaline whereas the adrenal cortex releases aldosterone, cortisol, and androgens. Moreover, while the medulla is not essential for life, the cortex is essential.

References

  1. https://journals.sagepub.com/doi/abs/10.1080/019262301301418847
  2. https://europepmc.org/article/med/976492

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