Explain the Concepts of Homeostasis Is with Reference to the Control of Heart Rate, Breathing Rate, Body Temperature and Blood Glucose Levels.

Explain the concepts of homeostasis is with reference to the control of heart rate, breathing rate, body temperature and blood glucose levels.

Homeostasis is simply the act of the body controlling and maintaining its internal self to ensure a constant steadiness and regulation of crucial internal factors such as heart rate, breathing rate, body temperature and blood glucose levels, despite the external environment. Homeostasis is vital as human cells are extremely demanding. It is important to note that the term ‘constant’ within this context is not referring to an absolute or fixed state of internal factors, however it is rather referring to internal factors being kept within a confined range. This assignment will endeavour to thoroughly explain the concepts of homeostasis including reference to the control of heart rate, breathing rate and various other internal factors.

Negative feedback in the body refers to the deviation of key variable’s accepted range limits, such as the PH of blood. This deviation provokes a response that returns the variable to within its designated range. An example of negative feedback can be seen within the liver. Once blood glucose levels fall, the liver glycogen converts into glucose to enable the vital energy levels to boost back up.

The brain and nervous system are mainly responsible for controlling homeostatic mechanisms and they also play a part in forecasting the possibility of key variables rising or falling beyond the boundaries of their accepted ranges. For example, if it has been a while since a person has ate a meal and they are feeling cold and tired the body will begin to crave a hot meal as a response to these feelings. This act is regarded as ‘feedforward’ as oppose to feedback. Negative feedback systems depend upon; receptors to detect change, a control centre to receive the information and process a response and effectors to reverse the transitions and re-establish a response. The majority of control centres can be found within the brain. [pic 1]

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 Homeostatic mechanisms for controlling heart rate

The autonomic nervous system controls the hearts activity. The autonomic nervous system consists of two branches; the sympathetic and the parasympathetic nervous system. These systems can be seen as acting like an accelerator and brake for the heart. The sympathetic nervous system is alert when the body is experiencing muscular work, fear or stress. This results in the heartbeat increasing in strength as well as rate. The parasympathetic nervous system is put into play when the body is relaxed and content.

Adrenaline boosts the sympathetic nervous system during stages of fight or flight. The sympathetic and the parasympathetic systems provide a cluster of cells to the right atrium. This is known as the sino-atrial node or the pacemaker.  The sympathetic and parasympathetic produce various impulses that have an impact upon the S-A node, this impact results in constant regulation of the heart to suit every condition. The S-A node is responsible for producing a collection of nerve impulses every few seconds, these impulses transmit across the branching network of atrial muscle fibres which in turn cause a contraction. The impulses are also caught by another group of cells in order to form the atrioventricular node and are then passed onto a band of purkinje fibres. The transition of impulses from the AV node are slightly delayed to enable the atria to finish their contractions and the atrio-ventricular valves to start to close. Heart valves are found between the atrial and ventricular muscle masses. The first part of the conducting tissue allows the excitatory impulses to transport to the ventricles, the tissue then splits into the right and left bundle branches which appear down either side of the ventricular septum, before transferring into the ventricular muscle masses. The impulses are now able to pass speedily to enable the two ventricles to contract in union, allowing the blood to be pumped around the body organs.