2.6 Hormonal Coordination in the Body

2.6 Hormonal Coordination in the Body

1. Hormones are the chemical substances produced by the ductless glands called endocrine glands.
2. Hormones are produced in a small quantity and are carried by the blood circulation system to all parts of the body.

2.6.1 Human Endocrine System
1. The endocrine system is made up of endocrine glands, which are ductless glands that secrete hormone directly into the bloodstream.

Human endocrine system and the location of endocrine glands

Endocrine glands
Function of hormone
Pituitary gland
•  names of hormones not required
•  Master gland that controls and regulates the secretion of hormones by other endocrine glands.
•   Controls the growth of body.
•   Controls the reabsorption of water.
•   Controls other endocrine glands like ovary and testes.
Thyroid gland
•  Thyroxine
(contains iodine)
•  Main source of iodine is seafood.
•   Controls metabolic rate.
•   Controls the physical and mental growth
•   Glucagon
Controls sugar level in the blood by:
•  Insulin converts excess glucose into glycogen.
•   Glucagon changes glycogen into glucose.
Adrenal glands
•   Adrenaline
(secreted during situations of emergencies, under stress, fear or anxiety)
Increase heartbeat.
Increase metabolic rate.
Increase breathing rate.
Converts glycogen into glucose.
the male sex hormones)
•   Testosterone
•  Controls the development of male secondary characteristics such as deepening of voice armpit hair and moustache.
•  Production of sperms.
the female sex hormones)
•   Oestrogen
•  Controls the development of female secondary characteristics such as development of breast and enlargement of pelvis.
•  Controls the menstrual cycle and ovulation.
•   Stimulates development of milk glands during pregnancy.

Effects of Hormonal Imbalance on Health
Effect of excessive hormone
Effect of deficiency of hormone
Growth hormone
•   gigantism
•  dwarfism
•  Increase metabolic rate
•  Increase heartbeat
•  Increase sweating
•  Protruding eyes
•  Metabolic rate decreases
•  Retarded growth in Children
Causes goitre
•  Shortage of glucose in the blood.
•  May lead to coma and fatal.
•  Diabetes Mellitus
High blood pressure.
•  High salt concentration in blood.
•  Blood sugar level increases.
•  Muscles weaken.
•  Ability to overcome stress reducing.
•  Excessive salt and water in the body (Addison disease).
•  Extremely masculine
•  Incomplete development of secondary sexual characteristics.
•  Immature sperms produced.
Extremely feminine.
Baby born before the complete gestation period.
•  Incomplete development of secondary sexual characteristics.
•  Irregular menstrual cycle
•  Infertility
•  Miscarriage

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