M2 - Discuss the probable homeostatic responses to changes in the internal environment during exercise.
What is homeostasis?
Homeostasis is defined as “maintaining a constant internal environment.”  The term internal environment refers to the area and components inside an individual’s body e.g. this consists of the blood, tissue fluid, body cell contents and all of the metabolic processes that occur. Constant means an ongoing process and too regulate and control. Homeostasis controls a range of conditions and physiological processes in the body such as body temperature, water content and blood glucose concentration. For example the homeostasis concept means that if it detects that the ...view middle of the document...
Lastly the required response is then carried out so that the internal environment can return to its optimum condition. For example the response could be activating sweat glands so that they can secrete perspiration which will evaporate and allow the body to cool down. There are two types of effectors, muscles and glands.
What happens in your body when you exercise?
When you exercise there are a number of changes that start to occur in the body. Firstly muscles become more active so they require more glucose for contraction and movement. For more glucose to be made the demand for oxygen also increases. If there is not a sufficient amount of oxygen then lactic acid will form (as a product of anaerobic respiration). But before this your body will try to access more oxygen by increasing the breathing rate. The human body makes three main changes when exercising to meet these demands, which I measured in the practical; an increase in heart rate, breathing rate and also body temperature. Below I have explained in-depth the details behind how each change happens.
Increase in heart rate
Conduction of the heart:
The heart is considered a very unique organ because it is able to contract (beat) on its own, making the cardiac muscle cells myogenic. The sinoatrial node (SAN) is located on the right atrium and initiates the heart beat so therefore acts as a natural pacemaker. It is a bundle of cells that control the rate of contraction by sending an electrical impulse across the atria creating the action atrial systole. There is also a second node called the atrioventricular node (AVN) that picks up on the electrical signal in the atria and transmits the signal down to the apex (at the bottom of ventricles). This electrical signal is passed via the bundle of His, which is a bundle of specialised cardiac muscle fibres. From the apex, the electrical activity is then spread through the ventricles by the purkinje fibres. The ventricles contract from the bottom upwards when they are filled with blood. (Biology guide, 2012)
The role of the ANS in increasing heart rate
The ANS stands for the autonomic nervous system, the ANS is a component of the nervous system and supplies internal organs e.g. blood vessels, kidneys & heart. The ANS plays a role in controlling the heart rate and is made up of two types of nerves, sympathetic and parasympathetic nerves. The sympathetic nerve’s function is to increase the rate & strength of the heart beat and works with a hormone called adrenaline. The parasympathetic nerve performs the opposite and its function is to decrease the heart rate when necessary.
Blood flows through a section of the brain called the medulla oblongata. The medulla oblongata contains chemoreceptors that can pick up on the CO2 concentration in the blood. When exercising the levels of CO2 in the blood increase and there is a low blood pH which the chemoreceptors are able to detect. The chemoreceptors send this information to the ANS which...