Psychology Study Material: Adrenal Gland and Division of Adrenal Gland

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Adrenal Gland

Synthesis and Location

  • Developed from different embryonic tissues, it secretes various hormones.
  • The adrenal/suprarenal is a paired gland and located near the upper portion of each kidney.

Division of Adrenal Gland

Each gland is divided into two parts:

  • An outer cortex and
  • An inner medulla

The cortex and medulla of the adrenal gland are just like the anterior and posterior lobes of the pituitary gland.

  • The adrenal cortex is essential to life because it has very important functions to perform, but the medulla may be removed with no life-threatening effects.
  • Hypothalamus effects and influences both portions of the adrenal gland but it involves different mechanisms i.e.. adrenal cortex is regulated by negative feedback which involves hypothalamus and adrenocorticotropic hormone.
  • Medulla is regulated by nerve impulses of hypothalamus.

Hormones of the Adrenal Cortex

  • The adrenal cortex consists of three different portions/regions, each region produces different type of hormones.
  • Chemically, all these cortical hormones are steroid.
Hormones of the Adrenal Cortex

Mineral Corticoids

  • Secreted by the outermost region of the adrenal cortex.
  • The main/principal hormone of mineralocorticoid is aldosterone, which acts to store/conserve sodium ions and water in the body.

Glucocorticoids

  • Secreted by the middle region of the adrenal cortex.
  • The main/principal hormone of glucocorticoid is cortisol, which increases blood glucose/sugar level in the body.

Gonad Corticoids

  • Also known as the sex hormones.
  • These are secreted by the innermost region of the adrenal cortex.
  • Adrenal cortex hormones, androgens (male hormones) and estrogens (female hormones) , are secreted in minimal amounts in both sexes, but their effect is usually influenced by the hormones from the testes and ovaries.
  • In females, the masculinization effect may become more evident after menopause. This occurs because the estrogen levels from the ovaries decrease.

Hormones of Adrenal Medulla

Develops from neural tissues.

Secretes two types of hormones:

  • Epinephrine and
  • Nor epinephrine

These are secreted in response to stimulation by sympathetic nerve, especially during stressful situations.

  • Lack of hormones from the adrenal medulla produces no significant effects,
  • Hyper secretion, e. g. , in case of a tumour, results in prolonged or continual sympathetic responses.

Gonads

  • Primary reproductive organs are testes in the male and the ovaries in the female.
  • These organs are responsible for producing the sperm and ova, but they also secrete other hormones, and that is why they are considered to be endocrine glands.

Testes

  • Male sex hormones (as groups) are called androgens of which the most important and influential is ‘testosterone’ ; secreted by the testes.
  • Small amount is also produced by the adrenal cortex.
  • Production of testosterone begins before birth. i.e.. during fatal development that continues for a short time after birth, nearly ceases during childhood, and then resumes at puberty.

This steroid hormone is responsible for:

  • The growth and development of the male reproductive organs.
  • Increase in the size of skeleton and muscular growth.
  • Larynx enlargement, accompanied by voice changes.
  • Growth and distribution of body hair.
  • Increased male sexual drive.
  • it՚s secretion is controlled and regulated by a negative feedback system and involves release of hormones from the hypothalamus and gonadotropins from the anterior pituitary.

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