Growth in Humans and Animals

15.7

Growth in Humans and Animals

Growth in multicellular organism such as humans and animals is an irreversible process which involve the increase in quantitive parameters such as size (height or length),body mass,volume and number of cells.
Parameters for the growth of humans: body size,height and length
Parameters for the growth of animals: body mass,fresh mass and dry mass

Growth in insects:

Organism with exoskeleton such as insects,crabs and prawns undergo growth by either complete metamorphosis or incomplete metamorphosis
In development of exoskeletal organisms, metamorphosis is a developement process from larval stage to adult stage
During development stage, organism undergoes a moulting process known as ecdysis
In complete metamorphosis, the growth of organisms involves four stages starts from egg to larva,larva to pupa and pupa to adult.
In incomplete metamorphosis, the growth of organisms only involves three stages starts from egg to larva and from larva to adult

Sigmoid growth curve of an organism:

Phase	Explanation
A (lag phase)	Slow growth rate Little or no cell division
B (exponential phase)	Growth rate at the fastest Cell division and cell elongation are active The size of organisms increase rapidly
C (slow growth phase)	Steady growth rate Limited by growth factor such as food shortage
D (stationary phase)	Form a plateau The growth rate is zero The organism reached maturity Cell division occurs to replace the dead cells
E (death phase)	The organism undergoes ageing and death

Growth curve of insects:

Source:[duncanrig.s-lanark.sch.uk]

Insects have a hard exoskeleton made of chitin
In order to growth in size, insects must undergo a moulting process known as ecdysis
The horizontal lines show zero growth periods known as instars
During ecdysis:

I: An insect breathes in a lot of air to expand the body
II: The old exoskeleton breaks
III: The insect expands by breathing in more air, before the new exoskeleton hardens
IV: Ecdysis is repeated several times until the adult phase

15.7

Growth in Humans and Animals

Growth in multicellular organism such as humans and animals is an irreversible process which involve the increase in quantitive parameters such as size (height or length),body mass,volume and number of cells.
Parameters for the growth of humans: body size,height and length
Parameters for the growth of animals: body mass,fresh mass and dry mass

Growth in insects:

Organism with exoskeleton such as insects,crabs and prawns undergo growth by either complete metamorphosis or incomplete metamorphosis
In development of exoskeletal organisms, metamorphosis is a developement process from larval stage to adult stage
During development stage, organism undergoes a moulting process known as ecdysis
In complete metamorphosis, the growth of organisms involves four stages starts from egg to larva,larva to pupa and pupa to adult.
In incomplete metamorphosis, the growth of organisms only involves three stages starts from egg to larva and from larva to adult

Sigmoid growth curve of an organism:

Phase	Explanation
A (lag phase)	Slow growth rate Little or no cell division
B (exponential phase)	Growth rate at the fastest Cell division and cell elongation are active The size of organisms increase rapidly
C (slow growth phase)	Steady growth rate Limited by growth factor such as food shortage
D (stationary phase)	Form a plateau The growth rate is zero The organism reached maturity Cell division occurs to replace the dead cells
E (death phase)	The organism undergoes ageing and death

Growth curve of insects:

Source:[duncanrig.s-lanark.sch.uk]

Insects have a hard exoskeleton made of chitin
In order to growth in size, insects must undergo a moulting process known as ecdysis
The horizontal lines show zero growth periods known as instars
During ecdysis:

I: An insect breathes in a lot of air to expand the body
II: The old exoskeleton breaks
III: The insect expands by breathing in more air, before the new exoskeleton hardens
IV: Ecdysis is repeated several times until the adult phase