Adrenal ( suprarenal ) glands , Pancreas , Sex glands (Gonads) & Gastrointestinal hormones

Adrenal ( suprarenal ) glands

They are two glands , where each one of them is located above one of the two kidneys , Each gland consists anatomically and physiologically of two regions which are : outer part that is called cortex , inner part that is called medulla , The hormones that secreted from the cortex differ from those secreted from the medulla .

Hormones of the cortex

The cortex of adrenal gland secretes a group of hormones that known as steroids which can be divided into three groups as the following :

Glucocorticoids : They include cortisone hormone and corticosterone hormone , They regulate the carbohydrate ( sugar – starch ) metabolism in the body .

Mineralocorticoids : They include aldosterone hormone that plays an important role in maintaining the mineral balance in the body , as it increases the reabsorption of sodium and excretion of the excess potassium through the two kidneys .

Sex hormones : Although the main sources of sex hormones are the testes in male and ovaries in female , there are similar hormones that secreted from the adrenal gland cortex such as the male sex hormone testosterone and female sex hormones oestrogen and progesterone .

If there is an unbalance in the secretion of adrenal cortex sex hormones and the sex hormones that are secreted from the special glands , it leads to the muscularixation in females , Feminization in males , Atrophy of gonads in both sexes ( if there is a tumour in the cortex of adrenal glands ) .

Adrenal glands

Adrenal glands

Hormones of the medulla

The medulla of adrenal gland secretes two hormones which are adrenaline and noradrenaline that are known as emergency hormones , They are responsible for the vital activities occurring in the body , when an individual is subjected to emergency situations such as fear , fight , excitation and during muscular exercises , as they :

  • Increase the sugar ( glucose ) level in the blood that results from the breakdown of glycogen which is stored in the river into glucose .
  • Increase the rate and force of heart contraction .
  • Increase the blood pressure .
  • Enable the muscles to take their demands of energy that is needed for their contraction ( as a result of the previous changes ) and increase the rate of oxygen consumption .

Pancreas

It is a mixed gland that gathers between the exocrine and endocrine glands where it pours its pancrestic juice ( digestive enzymes ) that are secreted from the pancreatic acini ( glandular cells ) through the pancreatic duct into the duodenum ( acts as an exocrine gland ) , It secretes hormones directly into the blood from groups of specialized small glandular cells that are called islets of Langerhans ( acts as endocrine gland ) .

The types of cells in islets of Langerhans

Alpha cells 

They are small in number and secrete glucagon hormone , It increases the sugar ( glucose ) level in the blood by increasing the breakdown of glycogen that is stored in the liver into glucose .

GlycogenGlucose           ,  ( Glucagon hormone )

Beta cells

They represent the majority of islets of Langerhans cells and secrete insulin hormone , It decreases the glucose level in the blood by :

  • Stimulating the oxidation and utilization of glucose in the different body tissues and cells to produce energy , where it stimulates the transport of all monosaccharides ( except fructose ) through the cell membrane to inside the cell to be used ( oxidized ) .
  • Controlling the relation between glycogen that is stored in the liver and glucose that is free in the blood , where it stimulates the conversion of glucose into glycogen or lipids to be stored in the liver and muscles or in the other body tissues .

GlucoseGlycogen or lipids                     , ( Insulin hormone )

Decrease in insulin hormone secretion leads to a disease called Diabetes Mellitus that is characterized by a disturbance in the metabolism of carbohydrates ( glucose ) and lipids .

Symptoms of Diabetes Mellitus disease :

  • The increase of glucose level in the blood above the normal level ( appears in analysis of blood and urine ) .
  • Continuous thirst sensation and excessive micturition , as a result of the increase of glucose amount in urine that is associated with the excretion of large amounts of water .

Glucagon hormone antagonizes the action of insulin hormone , Glucagon hormone and insulin hormone are directly related to the level of glucose in body as they preserve the glucose level constant in the blood which ranges between ( 80 – 120 milligram / 100 cm³ ) .

Sex glands ( Gonads )

The sex glands ( gonads ) are :

  • Testes produce male gametes ( spermatozoa ) .
  • Ovaries produce female gametes ( ova ) .

Gonads secrete a group of sex hormones that are responsible for the growth of genital organs and the appearance of secondary sex characters , They are two types which are male sex hormones and female sex hormones .

Male sex hormones

Male sex hormones are called androgens and include two hormones which are Testosterone hormone and Androsterone hormone , They are secreted from the interstitial cells in testis .

Functions :

  • The growth of prostate gland and seminal vesicles .
  • The appearance of male secondary sex characters .

Female sex hormones

Female sex hormones are called oestrogens and include three hormones which are :

  1. Oestrogen ( Oestradiol ) is secreted from the Graafian follicle of ovary , It helps in the appearance of female secondary sex characters such as the increase in the size of breasts and regulation of menstrual cycle .
  2. Progesterone is secreted from the corpus luteum of the ovary and placenta of the uterus , It is important during pregnancy as it regulates the vascularity of the uterine wall and prepares it to receive the embryo , It is responsible for the changes taking place in the mammary glands during pregnancy .
  3. Relaxin is secreted from the placenta and uterus , It causes the relaxation of the pubic symphysis at the end of pregnancy to facilitate the process of delivery .

Gastrointestinal hormones

The mucous membrane lining the alimentary canal contains a group of glands that secrete the digestive enzymes , It secretes a group of hormones that stimulates the different parts of alimentary canal ( glands ) to secrete the digesive juices such as :

  1. Gastrin that is secreted from the stomach wall and transferred through the blood to stomach again to stimulate it to secrete its gastric juice .
  2. Secretin and cholecystokinin that are secreted from the small intestinal wall and transferred through the blood to pancreas to stimulate it to secrete its pancreatic juice .

Endocrine system , Endocrine glands , Pituitary gland & Hormonal coordination in living organisms

Thyroid gland , Diseases of thyroid gland & Function of Parathyroid glands

Methods of reproduction in living organisms ( Asexual reproduction & Sexual reproduction )

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