Human Endocrine System

 
7.1  Human Endocrine System
 

1. Endocrine system is one of the system in the body that coordinates body functions that involve chemical substances

2. The endocrine system secretes hormones and causes an increase in 

  • Heartbeat
  • Rate of breathing
  • Blood pressure
  • Blood glucose level
  • Rate of metabolism

3. Endocrine gland: special glands that secrete hormone 

  • Ductless glands
  • Coordinates the activity of the body by responding to the stimulus from the environment
  • Hormone secrete directly into the blood circulatory system to be distributed to the whole body

4. Hormones

  • A type of protein
  • Slow response but prolonged effect
  • Stimulates the functions of specific tissues or organs
  • Secreted in small quantities

5. Target organ: has a suitable receptor that is able to recognise and respond to the specific hormone

6. Main endocrine glands

 
Endocrine gland Hormone and Function
Pituitary gland

Antidiuretic hormone (ADH)

  • Control the quantity of water reabsorbed by the kidneys

Growth hormone (GH)

  • Stimulates growth in children
  • Maintains healthy body composition in adults
  • Maintains the muscle and bone mass of adults
Thyroid gland

Thyroxine

  • Controls the rate of metabolism
  • Controls the physical and mental development in children
Adrenal gland

Adrenaline

  • Prepares your body to act in an emergency situation
Pancreas

Insulin

  • Controls the glucose level in the blood by converting excess glucose into glycogen to be stored in the liver
Ovary

Oestrogen

  • Controls the female secondary sexual characteristics
  • Stimulates the production of ova

Progesterone

  • Maintains the thickness of the wall of the uterus for the implantation of embryo
Testis

Testosterone

  • Controls the development of male secondary sexual characteristics 
  • Stimulates sperm production
 
7. Causes and effects of hormonal imbalance
 
Hormone Deficiency and Excessive
Tyroxine

Deficiency

  • Low rate of metabolism
  • Inability to tolerate cold
  • Cretinism
  • Myxedema
  • Goitre

Excessive

 

  • High rate of metabolism
  • Sweating 
  • Seeping difficulties
  • Thyroid gland enlargement
  • Protruding eyeballs
  • Swollen neck
Testosterone

Deficiency

  • Delay in reaching puberty
  • Low sperm count 

Excessive

  • Male characteristic in women
Oestrogen

Deficiency

  • Development of female secondary sexual characteristics to be disrupted

Excessive

  • Female characteristic in men
Growth hormone

Deficiency

  • Dwarfism

Excessive

 

  • Uncontrolled growth
  • Gigantism
Antidiuretic hormone (ADH)

Deficiency

  • Poor reabsorption of water at the collecting duct in the kidney
  • Excessive production of urine
  • Excessive thirst
  • Diabetes insipidus

Excessive

 

  • Headache
  • Dizziness
Insulin hormone

Deficiency

  • Failure of excessive glucose to be converted to glycogen
  • Increase in blood glucose level
  • Diabetes mellitus

Excessive

 

  • Low glucose levels
  • Hypoglycaemia
  • Excessive thirst