BTEC Applied Science Unit 9B: Homeostatic control of body systems. Homeostasis calls for a high degree of monitoring and control; to detect internal and external changes and respond
stimuli, hormones and nervous system communicate to bring about changes that brings symptoms back to the correct
le...
BTEC Applied Science Unit
9B: Homeostatic control of
body systems
, Homeostatic control of body system
Homeostasis- The constant maintenance of a constant internal environment within an organism.
One’s body needs to sustain its internal condition at certain levels to function. Homeostasis is called the preservation
of internal conditions such as pH, temperature, and salt concentration in a stable equilibrium.
Homeostasis is also known as a process of self-regulation by which an organism seeks to preserve equilibrium when
adapting to the optimal environment for its survival.
For example: homeostatic helps maintain optimal conditions for enzyme action and all cell functions, which then
helps metabolic reactions to occur at appropriate rates. What will happen if homeostatic dysfunctions for the
enzymes? As metabolic reactions involve enzymes, change in temperature such as increased body temperature will
denature enzymes preventing the enzymes from conducting metabolic reactions effectively. What will happen if fault
occurs in metabolic reaction? This will cause the organism to either have adequate or inadequate number of vital
substances required to remain healthy.
This helps us understand the significance of homeostasis’s role in an organism.
Feedback and control
Homeostasis calls for a high degree of monitoring and control; to detect internal and external changes and respond
stimuli, hormones and nervous system communicate to bring about changes that brings symptoms back to the correct
level.
How is does hormones and nervous system helps homeostatic? The endocrine and nervous system are crucial for
homeostasis.
Endocrine transmits information through hormones which travels through the blood.
Endocrine glands pass secretion directly into the blood stream rather than flowing a long
duct. Slower messages are sent through hormones which allows more than one tissue,
organ, or organ system to be targeted as it is carried around the body. Whereas Exocrine
glands contain ducts that transport secretion from the glands to its surface.
(Figure 1: the endocrine system)
The nervous system uses nerve cells which transfers information as electrical impulses.
Rapid messages are sent by the nervous system unlike endocrine.
(Figure 2: the nervous system)
These feedback mechanisms are used to track and control conditions within the organisms.
There are two main feedbacks called negative feedback and positive feedback:
Negative feedback
, The mechanism that reverses the change in internal conditions is called negative
feedback; reverses change inside the organism through the effectors restoring the
change back to the optimum.
(Figure 2.1)
Mechanism of negative feedback
The optimal point for the organism is tracked by the receptors.
They send signals to a co-ordinator (hormones or nervous system) when the receptors sense some changes
away from the optimum.
The co-ordinator (hormones or nervous system) then determines which response is sufficient and sends
signals to the effectors to carry it out.
Effectors bring about a transition that allows the internal regulatory changes to their optimal conditions.
How does co-ordinated response work?
Signals are obtained from several diverse sources by co-ordinators, these need to be evaluated before producing a
response to function effectively. For example, signals can come from several various receptors that covers diverse
types of stimuli and all this must be evaluated before sending the affecting signals.
For example, there are temperature receptors in both the skin (e.g., Arms) and in the hypothalamus (found deep
within the brain). As we exercise, we sweat, which lowers the skin temperature if the co-ordinator just. used skin
information, it will. work to boost the body temperature when we exercise, but instead the co-ordinator uses
hypothalamic as well as skin information to make an effective appropriate response.
(Figure 3: negative feedback in a central heating system)
An example of negative feedback
The hypothalamus in the brain regulates body temperature. The reaction is that the body starts to sweat to try to reduce
the temperature down to the correct amount if the hypothalamus senses that the body is too hot. Sweating will stop
until the body temperature is back to the correct amount. Conversely, if the hypothalamus senses that the body is too
cold, the reaction is that the body starts shivering to attempt to lift the temperature up to the correct amount. The
shivering will stop until the body temperature is up to the correct amount.
Positive feedback
Contrary to the negative feedback, positive feedback is the opposite: every change away from the sixed point is
increased. A significant, unstable changes within the organism is caused by this mechanism. It is typically harmful,
but there are instances when for example, its useful for action potential in neurons: nerve cells need to be able to
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