Heart rate
The heart is controlled by the autonomic nervous system which is made up of two branches:
Sympathetic nervous system
Parasympathetic nervous system
Both nervous systems contain a bunch of active cells in the top part of the right atrium.
The parasympathetic nervous system is active when a person is feeling relaxed.
The sympathetic nervous system however, becomes active when a person is exercising, feeling stress or fear. It causes the heart to beat stronger and increases the heart rate. Its nerves are the cardiac nerves and are powered by adrenaline when a person is in a fight, flight or fright situation. This is to overtake the homeostatic control of glucose, in order for the breakdown of glycogen into glucose to take place so that it can be used for energy to either fight, or flee from the situation. The secretion of adrenalin causes increased heart rate as it stimulates the S-A node to work faster. When the panic is over and the level of adrenaline in the body drops, the parasympathetic nervous system becomes active and the homeostatic controls go back to normal.
Also, when the body’s temperature increases, thermo receptors cause the hypothalamus to activate the sympathetic nervous system, which causes the heart to beat faster. The heart rate increases under pressure e.g. when a person is feeling stressed or has done exercise. This causes adrenaline to be released to provide the body with surge of energy which causes the blood pressure to increase. As this happens, glucose and oxygen are transported to our muscles which cause aerobic respiration.
Breathing rate
When a person breathes it is an involuntary process as homeostasis regulates this, unless a person is holding their breath or gasping. When the body produces more carbon dioxide than necessary, the persons breathing rate will increase until the excess carbon dioxide is removed from the body. A persons breathing slows down or stop temporarily until the carbon dioxide levels return to normal range During exercise, the body needs a large amount of oxygen as cells are respiring rapidly to produce ATP. To make up for this shortage of oxygen, the person breathes faster and their heart pumps faster to deliver the oxygen to the cells. After exercise, the person’s body will eventually reach homeostasis.
Also, when the cells produce ATP, it causes heat to be produced. In order to maintain homeostasis, the body has mechanisms to expel the heat, as well as sweating, vasodilation, etc.
M2. During exercise the muscles are being used more strenuously, therefore they need more oxygen, nutrients and energy. Because of this, the blood pumps faster and harder to transport oxygen around the body via the arteries and veins, in order to circulate blood faster to the muscles and respiring tissues to provide enough oxygen for the cells in order to respire and make energy for muscle contraction, therefore giving the body the ability to carry out movement.
Also, to increase the rate of the removal of waste gases such as CO2 and H2O which are left over from respiration.
Our heart rate increases as the hypothalamus detects a change, which causes the medulla within the brain to instruct the adrenal glands to release the hormone adrenaline during exercise, to give the body a surge of power, as well as glucose being released into the bloodstream for additional energy for the fight or flight response. This release of adrenaline causes the S-A node to work faster, causing the sympathetic nerves to accelerate the heart. Also, because the body’s temperature increases during exercise, the thermo receptors within the skin detect a rise in body temperature and cause the hypothalamus to get the sympathetic nervous system working.
As the heart rate increases, so does the breathing rate, in order to compensate for the production of carbon dioxide. The breathing rate increases as when a person exercises, the body makes extra carbon dioxide due to metabolism. The hypothalamus detects this increase of carbon dioxide in the body and the medulla within the brain instructs the lungs to breathe faster until the body has removed the excess carbon dioxide through expiration. Within the medulla there are groups of neurons which regulate the rate of respiration. The respiration rate can be affected by the amount of carbon dioxide in the blood, which stimulates chemoreceptors which causes impulses to be sent by the medulla to the intercostal nerves in order to increase the breathing rate.
Also, the body’s temperature increases as this is happening due to the amount of energy being burnt. Homeostatic mechanisms maintain the body temperature at a stable level to prevent the person from overheating. This is known as thermoregulation, which is controlled by the hypothalamus within the brain.
As the persons pores are closed, heat build ups in the person’s body, causing their temperature to rise. The hypothalamus will detect an alteration in the blood temperature, and respond to this by bringing down the heat, acting as a thermostat, by instructing the pores to open, so that the person will sweat in order to cool themselves down to prevent themselves from becoming overheated. Their blood vessels and capillaries will expand and come closer to the skin in order to allow heat to escape so the body does not overheat, known as vasodilation. As well as this, the person’s body hair will lie flat against the body to allow heat to escape as hair acts as an insulator when a person is cold by standing up on end to trap a layer of heat.
During exercise, the blood sugar levels decrease as the muscles use it up for energy. When this occurs, the pancreas detects a change in the blood t-cells and releases the hormone glucagon. The liver then breaks the glycogen down, turning it into glucose releasing glucose in order to restore blood glucose levels.
D2.
Homeostasis is vital for the maintenance of healthy functioning of the body. It is important the body keeps to a narrow range of variables, and without it , chemical reactions and metabolic processes within the body cannot be carried out properly, which can cause disease and complications.
If the body cannot maintain its temperature, this can cause the person to overheat, resulting in hyperthermia. This would be fatal as the body cells would become destroyed as well as the body’s enzymes, which would mean that the organs would not be able to function and metabolic reactions would not be able to take place which would result in death.
Also, if the persons temperature was to fall too low and not be brought back to normal by homeostasis, the person would result in hypothermia, also causing the body’s cells to be destroyed as they cannot survive under body temperature lower than 37 degrees, as well as the body’s enzymes to be destroyed as they also require normal body temperature to function, again resulting in death.
If the body could not maintain the blood glucose level, this could be dangerous as the blood sugar levels could fall and the body won’t be able to bring them back to normal range, resulting in hypoglycaemia as a result of the pancreas producing excess insulin and also type 1 diabetes.
Extremely low blood sugar levels can cause severe symptoms such as fits, trembling, blurred vision etc. and if not treated in time, can even be fatal.
Whereas having high blood sugar levels can cause Hyperglycaemia, which can damage blood vessels which supply blood to vital organs, an increased risk of heart disease and strokes, kidney disease, problems with, and also nerve problems in people who have diabetes, which can also be fatal if not treated in time, causing other life threatening complications such as Ketoacidosis, which occurs as a result of lack of insulin in the blood.
If the body could not maintain the heart rate this could be dangerous because if it is too high and cannot be brought back down to normal, it could cause unnecessary strain on the body, using up more energy than required which the body could not keep up with and would result in death. Also, the heart beating too fast could cause decreased perfusion of oxygen to the vital organs which would be fatal if not treated but also possibly a heart attack if it continued to increase. If the heart rate was too low, this could cause the bodys oxygen levels used by your muscles to lower, resulting in the person becoming weak and even suffocate in severe cases .
If the body’s breathing rate could not be maintained and the breathing rate was too high, this could result in hyperventilation which could cause a condition called alkalosis, resulting in less oxygen being released to tissue cell, causing the body to not have enough energy to function as efficiently as it normally would.
If the persons breathing rate was too low this could result in hypoventilation which could be life threatening as the person could stop breathing which would result in death.
,
