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Unit 5 Anatomy and physiology
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Kofoworola Abdullahi 40135191P5 Explain the concept of homeostasis with reference to the control of rate heart rate,
breathing rate, body temperature and blood glucose levels.
Homeostasis is the process of maintaining a constant internal environment despite external
changes, the internal environment that consists of blood, tissue fluid, body cell contents and
all the metabolic processes taking place.
Homeostasis is the maintenance of a stable internal environment within an organism and
maintaining a stable internal environment in a human means having to carefully regulate
many parameters, including glucose levels in the blood. There are two major ways that
signals are sent throughout the body. The first is through nerves of the nervous system.
Signals are sent as nerve impulses that travel through nerve cells, called neurons. These
impulses are sent to other neurons or specific target cells at a specific location of the body
that the neuron extends to. Most of the signals that the human body uses to regulate body
temperature are sent through the nervous system.
The second way that signals can be sent throughout the body is through the circulatory
system. These signals are transmitted by specific molecules called hormones, which are
signalling molecules that travel through the circulatory system. In this lesson, we'll take a
look at how the human body maintains blood glucose levels through the use of hormone
signalling.
NEGATIVE FEEDBACK AS A REGULATORY MECHANISM.
Negative feedback is a key regulatory mechanism for psychological functions in living things.
Your body has its own internal controller for maintaining its temperature, pH, hormone levels,
blood sugar and other internal variable levels at homeostasis, which is the optimal internal
state at which your body operates best. The controller of homeostasis in most animals is the
hypothalamus. Without this structure in the brain, organisms would have great difficulty
functioning normally.
There are many negative feedback pathways in biological systems, including:
Temperature regulation
Blood pressure regulation
Blood sugar regulation
Thyroid regulation
Photosynthesis in response to increased carbon dioxide
Predator/prey population dynamic
Examples of Negative Feedback Loops:
This diagram shows the steps of the negative feedback loop, as well as how it works in
temperature regulation.
, Kofoworola Abdullahi 40135191
As you can see, the body exceeds a certain temperature. This is detected by nerve cells that
report back to the part of the brain that regulates temperature, and the brain sends out a
signal for the body to cool itself down by sweating. Pretty efficient!
What is homeostasis responsible for?
The homeostatic mechanism for regulation of heart rate
The autonomic nervous system controls the heart and it consists of two branches, the
sympathetic nervous system (SNS)and parasympathetic nervous system (PMS). The two
systems perform the function of an accelerator or brake on the heart. The SNS is always
active during stress and fear because it causes the heart rate to increase, the PNS is always
active during resting and contentment so it causes the heart rate to decrease.
The two most important centres for controlling the heart, the heart rate is located in the
brainstem or medulla. Baroreceptors are responsible for detecting the change in blood
pressure, they are located in the walls of the aorta and the carotid arteries .receptors that are
sensitive to temperature are called thermoreceptors, they can be found in the skin and deep
inside the body .they rely on impulses to relay information to the hypothalamus that activates
suitable feedback system, Furthermore when adrenaline is released from the adrenal gland
during fear, stress or exertion it causes the S-A node to work faster .this increases the effect
of the SNS. Thermoreceptors cause the hypothalamus to activate the SNS which causes the
heart rate to increase.
Homeostasis for the regulation of body temperature
Homeostasis of body temperature is really important and vital because it keeps the inner
part of the body at normal temperature and allows the periphery to adapt to external
environment .the skin plays a major role in homeostatic as the regulation of the body
temperature has many functions, the functions of the skin are there to protect tissues against
friction damage, to waterproof the body, to protect deeper structures from invasion by
microorganisms, to protect against ultraviolet radiation, for thermoregulation, to relay nerve
impulses for heat, cold, touch, pain and pressure and to synthesise vitamin D .heat is
produced in the body by the metabolic processes which occur in the body, Many chemical
reactions take place in the liver which is a massive generator of heat in the body .the liver
does not feel hot because most of the heat is distributed around the body, heat can also be
gained from hot food, hot drinks, or the sun. Furthermore, there are four ways in which the
body loses heat in order to cool off, conduction, convection, radiation and evaporation of
sweat.
The hypothalamus in the brain can be known as the temperature control centre, it sends
nerve impulses to muscles, sweat glands and skin blood vessels .the PNS also has a huge
role in thermoregulation, shivering, stamping our feet, swinging our arms, rubbing our face
hands and feet are ways to warm the body up.
The homeostatic mechanism for regulation of breathing rate.
If breathing is on autopilot we do not notice small changes to our temperature which are
caused by homeostatic regulation, we can only control our breathing voluntarily by speaking,
taking deep breaths or holding our breaths.
Internal receptors can be stretched receptors found in muscles and tissues, they relay
impulses to the brain about the status of ventilation from the degree of stretch of muscles
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