First proposed by Canadian-born American ecologist Robert MacArthur in 1955, homeostasis in ecosystems is a product of the combination of biodiversity and large numbers of ecological interactions that occur between species.

1. AIHTESHAM JADOON
Presentation: Introduction to Homeostasis

2. What Is Homeostasis
 The ability of an organism to maintain its internal body
stability is called homeostasis .

3. Maintaining homeostasis/Homeostasis Mechanisms
 Homeostasis is maintained by a complex system that consists of individual units
working in a particular sequence to balance a given variable. All homeostasis
mechanisms consist of four separate units, which are:
1. Stimulus
2. Sensor/ Receptor
3. Control unit
4. Effector

4. 1. Stimulus
 The stimulus is something that results in changes within the
system involving the variable.
 The stimulus represents that the variable has moved away
from its normal range, initiating the process of homeostasis.
 One example of this is the increased temperature of the body
above 37°C due to various causes.The increased temperature
indicates that the temperature of the body has gone higher
than its higher range.

5. 2. Sensor/ Receptor
 The sensor or receptor is the sensing unit of homeostasis,
where it monitors and responds to the changes in the body.
 The changes in the system are realized by the sensor, which
then sends the information to the control unit.
 The nerve cells and receptors like thermoreceptors and
mechanoreceptors are examples of sensor/ receptors.

6. 3. Control unit
 Once the information is sent to the control unit, it tallies the
changed value to its normal value.
 If the value is different from the normal value, the control
center activates the effectors against the stimulus.
 The thermoregulatory unit in the hypothalamus of the brain
that controls the temperature of the body is an example of the
control unit.

7. 4. Effectors
 Effectors can be muscles, organs, glands, or other similar
structures that are activated as a result of the signal from the
control unit.
 An effector is a target which is acted upon by the control unit to
bring the value of variable back to normal.
 The effector essentially counteracts the stimulus to nullify its
effect.
 In the case of thermoregulation, the sweat glands are effectors
that are acted upon by the thermoregulatory unit to produce
sweat so as to bring the value of body temperature back to its
normal value.

8.  homeostasis is the state of steady internal, physical and chemical
conditions maintained by living systems
 Generally, there are three types of homeostatic regulation in
the body
 All homeostasis mechanisms consist of four separate units, which
are:
1. Stimulus
2. Sensor/ Receptor
3. Control unit
4. Effector

9. Types of Homeostatic Regulation in the
body
 A number of homeostatic regulation processes, balancing the
chemical or physical parameters, take place in the human
body. Generally, there are three types of homeostatic
regulation in the body, which are:

10. 1 Thermoregulation
 Thermoregulation is the process occurring inside the body
that is responsible for maintaining the core temperature of
the body.
 Thermoregulation works by the negative feedback loop where
once the body temperature is either increased or decreased
beyond its normal temperature, it is brought back to normal.

11. Amphibian & Reptile Thermoregulation
 All amphibians and reptiles are ectotherms •Their body
temperature is governed by the environment
 Two primary methods of thermoregulation
 • heliotherms (gain heat by absorbing solar radiation, basking)
 • thigmotherms (gain heat by absorbing conducted heat from
substrate, under cover objects)

12.  •Salamanders - Movement between underground (cold
nights) and cover objects at the surface (warm days)
 Frogs - Movement between middle of the pond (cold nights)
and the shore (warm days)
 Many turtles burrow into muds at the bottom of ponds

15. 2. Osmoregulation
 Osmoregulation is the process of maintaining a constant osmotic
pressure inside the body by balancing the concentration of fluids
and salts.
 During this process, excess water or ions or other molecules like
urea are removed from the body to maintain the osmotic balance.
 One classic example of this process is the removal of excess water
and ions out of the blood in the form of urine to maintain the
osmotic pressure of the blood.

17. 3 Excretion
 Removal of waste from body is know as excretion .
 Through :
 Kidney
 Liver
 Skin
 Lungs
 Etc .

19. 3.1 Chemical regulation
 Chemical regulation is the process of balancing the concentration
of chemicals like glucose and carbon dioxide in the body by
producing hormones.
 During this process, the concentration of hormones like insulin
increases when the blood sugar level increases in order to bring
the level back to normal.
 A similar process is observed in the respiratory system, where the
rate of breathing increases as the concentration of carbon dioxide
increases.