HORMONAL CO-ORDINATION
Coordination in mammal s is done by both nervous system and hormonal (endocrine) system.
Endocrine system is made of the endocrine glands that secrete different hormones.
Hormone is a chemical substance produced by endocrine glands, carried in the blood and alters
activity of one or more target organs.
ENDOCRINE AND EXOCRINE GLANDS
Endocrine glands are ductless and their secretion directly gets into the blood whereas exocrine
glands have ducts that carry secretion from the glands to the where they have to work.
Examples of endocrine glands are thyroid gland, islets cells of pancreas, adrenal glands, etc
Examples of exocrine glands are salivary glands, pancreas, sweat glands etc
LOCATION OF ENDOCRINE GLANDS IN THE BODY
1
ENDOCRINE GLANDS, THEIR HORMONES AND FUNCTIONS OF HORMONES
ENDOCRINE HORMONE(S) SECRETED TARGET ORGAN(S) FUNCTION OF THE HORMONE
GLAND
PITUITARY 1. Growth hormone All body parts -Stimulates growth
2. Follicle Stimulating Ovary -Stimulates development of the
hormone follicle in ovary
3. Luteinising Hormone Ovary -Initiates ovulation
4. Anti - diuretic Kidney -Makes kidney to re –absorb
Hormone more water
5.Thyroid Stimulating Thyroid gland -Stimulates thyroid gland to
Hormone secrete thyroxine
THYROID Thyroxine All body parts Regulates metabolic rate
ADRENAL Adrenaline Heart, lungs, muscles, Prepares the body for action
eyes
PANCREAS 1. Insulin Liver -Stimulates liver cells to
convert excess glucose to
2. Glucagon Liver glycogen
-Stimulates liver cells to
convert glycogen to glucose
OVARY 1. Progesterone Uterus -Maintains thickness of the
lining of the uterus
2. Oestrogen Uterus -Initiates thickening of the
lining of uterus lining
TESTICLES testosterone Muscles and testicles Stimulates testicles to produce
hormone and produce
secondary sexual
characteristics
NOTE: Functions of Insulin and Glucagon were covered under digestive system and testosterone,
progesterone and oestrogen were covered under reproduction
FUNCTION OF ADRENALINE
It prepares the body for action. Such action are fighting, fleeing, taking part in competition etc
CONDITIONS UNDER WHICH ADRENALINE IS SECRETED
Below are conditions that lead to secretion of adrenaline:
Fear, just before competition, stress, anxiety, excitement
EFFECTS OF ADRENALINE
Breathing rate increases and becomes deeper. This increases the rate at which oxygen is
supplied into the body
Increases rate of heart beat. This increase delivery of oxygen and nutrients to respiring cells
and rate of removal of waste products from the cells.
2
Stimulates conversion of glycogen into glucose. This provides the respiring cells with
glucose.
Increases the uptake of glucose by cells. This increases the rate of breathing.
COMPARISON OF NERVOUS AND ENDOCRINE SYSTEM
FEATURE NERVOUS SYSTEM ENDOCRINE SYSTEM
Type of message Electrical impulses Chemicals called hormones
Pathway neurones blood
Speed of transmission Very fast slow
Duration of response Short lived Long lived
Type of response Both voluntary and involuntary All involuntary
Target organs specific widespread
NEGATIVE FEEDBACK
This refers to a response that counteract the effect which produced the response that was occurring.
Eg. When it is cold, impulses are sent to skin to cause vasoconstriction, shivering, erection of hair so
that the body temperature is adjusted to normal level. After the body temperature, if it is increased
above normal level, other impulses are sent to the skin to cause vasodilation, more sweating, hair
lying on skin
Eg 2. Pituitary gland secrete ADH so that it stimulate kidney to reabsorb more water, if the blood
become too dilute, secretion of ADH stop so that concentration of blood can be normal
