P5 – Explain the concept of homeostasis with reference to the control of heart rate,
breathing rate, body temperature and blood glucose level
In this assignment, I will be explaining the concept of homeostasis. I will also include reference to the control of
heart rate, breathing rate, body temperature rate and blood glucose level.
What is homeostasis?...
Homeostasis is the process of the body maintaining a constant internal environment despite the external
environment changing.
Homeostatic mechanisms for regulation of heart rate;
The autonomic nervous system controls the heart and it has two branches, the sympathetc nervous system (SNS)
and parasympathetc nervous system (PNS). The two systems can be seen as an accelerator and brake on the heart.
The SNS is actve during fear and stress so it causes heart rate to increase, however, the PNS is actve during restng
and contentment so it causes heart rate to decrease. The two important centres for control of heart rate are located
in the brain stem or the medulla. Baroceptors are responsible for detectng change in blood pressure, they are
located in the walls of the aorta and carotd arteries. Receptors sensitve to temperature are called thermoreceptors
and they can be found in the skin and deep inside the body. They use relay impulses to relay informaton to the
hypothalamus which actvates suitable feedback systems. Furthermore, when adrenaline is released from the
adrenal gland during fear, stress or exerton it causes the S-A node to work faster. This increases the efect of the
SNS. Thermoreceptors cause the hypothalamus to actvate the SNS which causes heart rate to increase.
Homeostatic mechanisms for regulation of breathing rate;
Or breathing is on auto-pilot so we do not notce small changes to our temperature which are caused by homeostatc
regulatons. We only control our breathing voluntarily when we speak, take deep breaths or hold our breath.
Internal receptors can be stretch receptors found in muscles and tssues. These relay nervous impulses to the brain
about the status of ventlaton from the degree of stretch of muscles and other tssues. Furthermore, The SNS causes
bronchial muscles to relax and the PNS causes them to contract which results in narrowing of the bronchi. The
cerebral cortex in the brain is responsible for voluntary control of breathing. The involuntary centre which is called
the respiratory centre, is located in the medulla and area just above. Each centre receives informaton from internal
receptors regarding the state of ventlaton.
Homeostatic mechanisms for regulation of body temperature;
Homeostatc regulaton of body temperature is vital because it keeps the inner core of the body at normal
temperature and allows the periphery to adapt to external temperature. The skin plays a major role in homeostatc
regulaton of body temperature and has many functons. The functons of skin are to protect tssues against fricton
damage, to waterproof the body, to protect deeper structures from invasion by micro-organisms, to protect against
ultra-violet radiaton, for thermo-regulaton, 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 reactons take place in the liver, which is a massive generator of heat for 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 of conducton, convecton,
radiaton and evaporaton of sweat. The hypothalamus in the brain can also 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
thermo-regulaton. Shivering, stamping our feet, swinging our arms, rubbing our face, hands and feet are ways to
warm the body up.