 Explain what is meant by endocrine glands
 Compare enzymes and hormones
 Differentiate between endocrine system and nervous system
 Discuss general properties of hormones
CIRCULATORY SYSTEM
EXCRETORY SYSTEM
DIGESTIVE SYSTEM
RESPIRATORY SYSTEM
The Nervous System and the Endocrine System
are the two main controlling and coordinating systems of the body
Introduction
• Endocrine glands:
ductless glands that
secrete hormones directly
into blood
• Hormones: Chemical
messengers carried by
blood that regulate effects
on specific cells or organs
• Nervous System and
Endocrine glands together
control and co-ordinate
the body
• Hormones are similar to
enzymes
Introduction
Nervous System
Endocrine System
Immediate/spontaneous activity
Slow
Transmitted electrochemically
through nerve fibres &
chemically across synapses
Transmitted as chemical
through blood
Affects particular gland/muscle
Affects any organ
Only short-term effect
Long-lasting or short-term effect
Cannot affect growth
Affects growth
Does not influence chemical
changes
Brings about specific chemical
changes
Does not regulate chemical
metabolism
Regulates chemical metabolism
General Properties of Hormones
• Secreted directly into blood
• Regulate processes by chemical means
• Act on target organs/cells away from their
source
• Produced in very small quantities and are
biologically very active
• Some are peptides, amines and steroids
• Excess and deficiency has serious results
• Not stored in system; excreted
Enzymes
Hormones
Act close to or within same cell
Act at sites away from source
Not transported by blood;
sometimes ducts present
Transported by blood
Specific; acts as catalyst in one
type of reaction
Show varied action on different
tissues in same/different
organism