H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 9: Human Regulation and Reproduction
Assignment 9B: Understand the homeostatic
mechanisms used by the human body
Homeostasis
Homeostasis is the regulation and maintenance of a stable internal environment
which involves mechanisms that maintain your internal environment by keeping
it relatively constant. It is important for your internal environment to remain
stable so that cells are able to function normally and to prevent them being
damaged. The internal environment can be affected by changes in your external
environment. To maintain a stable internal environment, the core body
temperature must be controlled, as well as the blood pH. This is because both
these can have an effect on enzyme activity and enzymes control the metabolic
rate of reactions in our body.
For example, if the body temperature is detected as too high (e.g. 40˚C), this
could cause enzymes to become denatured, meaning metabolic reactions may
become less efficient. On the other hand, if the body temperature is detected as
too low, enzyme activity may be reduced, therefore the rate of metabolic
reactions would become too slow. For enzymes to be working efficiently, the
optimum body temperature is around 37˚C in humans.
In terms of blood pH, if it is detected as too high/low (very alkaline/acidic),
enzymes can also become denatured in this way, therefore leading to the
inefficiency of metabolic reactions. This is because enzymes have a highly
specific tertiary structure which is held by hydrogen bonds that can break when
the pH gets too low or high, altering the shape of its active site as a result. For
enzymes to be functioning efficiently, the optimum blood pH is around 7
(neutral), although other enzymes may work efficiently at other pHs, e.g.
enzymes in the stomach work best at a low pH.
Along with maintaining the body temperature and blood pH, it is also equally as
important to maintain the concentration of glucose in our blood as glucose is
needed for energy. Blood glucose concentration can also have an effect on water
potential of blood. For example, if blood glucose concentration is found to be too
high, this could lead to the water potential of blood being reduced where water
molecules diffuse out of the cells via osmosis. This can cause the cells to become
shrivelled up and die. Alternatively, if blood glucose concentration is found to be
too low, cells may not be able to carry out energy-requiring activities as they
don’t have enough glucose for respiration to supply energy.
Overall, it is essential for the body to maintain a stable internal environment so
that cells can continue to function as normal and so that the body can carry out
activities as normal without becoming damaged.
Positive feedback
Positive feedback is a mechanism that happens in nature when the product of a
reaction causes an increase in that reaction. In relation to homeostasis, a
positive feedback mechanism moves a system (e.g. body temperature) further
away from the normal level (e.g. optimum body temperature of 37˚C) and
continues to move it unless action is taken.
1
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 9: Human Regulation and Reproduction
Positive feedback mechanisms can occur when a homeostatic system breaks
down, e.g. if your body temperature drops over long periods of time.
Hypothermia is an example of
a positive feedback mechanism Figure 1.1 – Graph of positive feedback mechanism of
as it is where the body is at a hypothermia
low temperature (e.g. below
35˚C) due to heat escaping
quicker than it can be
produced. This mechanism
works by taking the low body
temperature further away
from the normal level until
the brain doesn’t function
properly and shivering stops-
where the body temperature
falls even more (refer to
Figure 1.1).
Positive feedback mechanisms aren’t associated with homeostasis as they don’t
help maintain your internal environment. These mechanisms are mainly useful
for quickly activating something, e.g. a blood clot after an injury.
Negative feedback
Negative feedback is a mechanism that happens in biology when the product of
a reaction causes a decrease in that reaction. In relation to homeostasis, a
negative feedback mechanism brings a system closer to the normal level (e.g.
body temperature) and there are multiple negative feedback mechanisms for
homeostasis, such as thermoregulation, blood glucose regulation and
osmoregulation (discussed in more detail on pages 7-17).
For example, when the Figure 1.2 – Graph of how negative feedback controls the
body temperature is body temperature
detected as too high,
negative feedback
mechanisms return it to
the normal level by
decreasing the body
temperature towards the
normal level. As shown in
Figure 1.2 below, this
mechanism works by the
effectors responding to
the hot temperature by
decreasing the
temperature.
Alternatively, if the body
temperature is detected as too low, the effectors will respond by increasing the
temperature.
2
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 9: Human Regulation and Reproduction
Assignment 9B: Understand the homeostatic
mechanisms used by the human body
Homeostasis
Homeostasis is the regulation and maintenance of a stable internal environment
which involves mechanisms that maintain your internal environment by keeping
it relatively constant. It is important for your internal environment to remain
stable so that cells are able to function normally and to prevent them being
damaged. The internal environment can be affected by changes in your external
environment. To maintain a stable internal environment, the core body
temperature must be controlled, as well as the blood pH. This is because both
these can have an effect on enzyme activity and enzymes control the metabolic
rate of reactions in our body.
For example, if the body temperature is detected as too high (e.g. 40˚C), this
could cause enzymes to become denatured, meaning metabolic reactions may
become less efficient. On the other hand, if the body temperature is detected as
too low, enzyme activity may be reduced, therefore the rate of metabolic
reactions would become too slow. For enzymes to be working efficiently, the
optimum body temperature is around 37˚C in humans.
In terms of blood pH, if it is detected as too high/low (very alkaline/acidic),
enzymes can also become denatured in this way, therefore leading to the
inefficiency of metabolic reactions. This is because enzymes have a highly
specific tertiary structure which is held by hydrogen bonds that can break when
the pH gets too low or high, altering the shape of its active site as a result. For
enzymes to be functioning efficiently, the optimum blood pH is around 7
(neutral), although other enzymes may work efficiently at other pHs, e.g.
enzymes in the stomach work best at a low pH.
Along with maintaining the body temperature and blood pH, it is also equally as
important to maintain the concentration of glucose in our blood as glucose is
needed for energy. Blood glucose concentration can also have an effect on water
potential of blood. For example, if blood glucose concentration is found to be too
high, this could lead to the water potential of blood being reduced where water
molecules diffuse out of the cells via osmosis. This can cause the cells to become
shrivelled up and die. Alternatively, if blood glucose concentration is found to be
too low, cells may not be able to carry out energy-requiring activities as they
don’t have enough glucose for respiration to supply energy.
Overall, it is essential for the body to maintain a stable internal environment so
that cells can continue to function as normal and so that the body can carry out
activities as normal without becoming damaged.
Positive feedback
Positive feedback is a mechanism that happens in nature when the product of a
reaction causes an increase in that reaction. In relation to homeostasis, a
positive feedback mechanism moves a system (e.g. body temperature) further
away from the normal level (e.g. optimum body temperature of 37˚C) and
continues to move it unless action is taken.
1
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 9: Human Regulation and Reproduction
Positive feedback mechanisms can occur when a homeostatic system breaks
down, e.g. if your body temperature drops over long periods of time.
Hypothermia is an example of
a positive feedback mechanism Figure 1.1 – Graph of positive feedback mechanism of
as it is where the body is at a hypothermia
low temperature (e.g. below
35˚C) due to heat escaping
quicker than it can be
produced. This mechanism
works by taking the low body
temperature further away
from the normal level until
the brain doesn’t function
properly and shivering stops-
where the body temperature
falls even more (refer to
Figure 1.1).
Positive feedback mechanisms aren’t associated with homeostasis as they don’t
help maintain your internal environment. These mechanisms are mainly useful
for quickly activating something, e.g. a blood clot after an injury.
Negative feedback
Negative feedback is a mechanism that happens in biology when the product of
a reaction causes a decrease in that reaction. In relation to homeostasis, a
negative feedback mechanism brings a system closer to the normal level (e.g.
body temperature) and there are multiple negative feedback mechanisms for
homeostasis, such as thermoregulation, blood glucose regulation and
osmoregulation (discussed in more detail on pages 7-17).
For example, when the Figure 1.2 – Graph of how negative feedback controls the
body temperature is body temperature
detected as too high,
negative feedback
mechanisms return it to
the normal level by
decreasing the body
temperature towards the
normal level. As shown in
Figure 1.2 below, this
mechanism works by the
effectors responding to
the hot temperature by
decreasing the
temperature.
Alternatively, if the body
temperature is detected as too low, the effectors will respond by increasing the
temperature.
2
