What is homeostasis?
Homeostasis is the mechanism in our body that regulates and maintains a stable and constant environment. This enables our body to respond to changes in the environment around us as. The homeostatic mechanisms in our body, observe and monitor conditions and will then make a judgment whether to change the way the body functions is order to adapt to the outside surroundings better. The main organs involved in homeostasis are; the brain, liver, skin and kidney’s. The skin is involved as its acts as a protective layer and also regulates body temperature. The liver breaks down harmful substances and the kidneys regulate water levels and waste products. In the brain the hypothalamus controls everything and changing them to fit into the outside surroundings. Negative feedback is also linked in as it is the process of homeostasis. It is negative because it is in a negative situation and will not kick it unless there’s something wrong.
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When we exercise the body has to work harder, the body temperature would increase this is due to organs having to work harder to get oxygen to muscles. The metabolic rate that produces more energy has to increase in order for more energy to be released. The heart has to pump more blood around the body in order to deliver oxygen to the working muscles so they can carry on working at that capacity. What mechanisms are there to cool the body down?
Sweating-glands are stimulated to release sweat
Liquid turn into gas
Vasodilation-your body carries most of the heat energy around your body There are capillaries underneath your skin that can be filled with blood if you get too hot This brings the blood closer to the surface of the skin so more heat can be lost, this is why we look red when we’re hot. What mechanisms are there to warm the body up?
Vasoconstriction-this is the opposite of vasodilation
The capillaries underneath your skin get constricted (shut off) so less heat is lost Piloerection- this is when the hairs on your skin stand up
The hairs trap a layer of air next to the skin which is then warmed by the body heat.
The heart rate is controlled by the autonomic nervous system. This system however, is split into two, the sympathetic nervous system and the parasympathetic system. The sympathetic system is in charge of speeding up the heart rate when it’s needed and the parasympathetic system is there to slow the heart rate down. There are many reasons why heart rate could increase; the main and obvious reasons are fear, stress and exercise. Exercise is one of the main reasons why heart rate would increase as when we exercise we need more oxygen to travel to our working muscles. Oxygen is only carried in the blood and the main organ for the blood pumping around the body is the heart. This is when the sympathetic nervous system comes in; the receptors tell the brain that we are doing exercise and then the brains sends a message to the heart to pump faster, in order for more oxygen to be transported in the blood to the working muscles. When we are not doing exercise we have a ‘pace maker’ of the heart. This ‘pace maker’ called the Sino atrial node keeps a regular heart beat. We have tested our Sino atrial node by first of all doing exercise to see our risen heart rate, mine was 13. After 5 minutes of rest our Sino atrial node should have kicked in and our regular heart beat will be taking place, mine was now 11. The negative feedback system
Change in the body’s external environment, the brain receives a message – exercise Change in body’s internal system
Receptors detect change and send messages to the brain
The brain organises internal and external body changes to bring the environment back to normal
Breathing rate is determined by the amount of breaths taken during a certain period of time. This can increase during exercise or any physical activity or trauma. The way in which the body recognises this is by the chemo-receptors. They send a message to the brain, which then sends a message to the heart to pump more blood by beating faster, this is because they have detected a change in the amount of carbon dioxide that is circulating the body. When the chemo-receptors detect a high level of carbon dioxide, they send a message to the brain to increase or decrease breathing rate in order to get rid of carbon dioxide or to replenish the amount of oxygen in the body. What happens next is very clever in the fact that the body recognises that during exercise we need more oxygen. Therefore messages in the form of nerve impulses are sent to the diaphragm causing it to contract. When the diaphragm contracts it lowers itself in order for the ribs to expand and move upwards so there is increased space for the lungs to inflate. The muscle that allows the ribs to move up and out is called the inter costal muscle. This process of breathing rate is called inspiration. When we exhale the reverse happens to what has just been explained. The diaphragm relaxes and returns to its original position. The inter costal muscle that allows the ribs to move up and out also relaxes and returns the ribs to their stationary position. This process is known as expiration.
Blood glucose is simply the control of sugar levels in the body, and determines when the body needs more glucose (sugar) or when it needs less. The part of the body that controls the glucose is the pancreas. The pancreas releases insulin which is made to lower blood sugar levels when it gets too high but can also create glucagon that brings the blood sugar levels up when they are too low. Blood sugar levels mainly are affected and altered by the food we eat. Before a meal our blood sugar levels will be running low but after we’re eaten our blood sugar levels will be a lot higher, and in many cases will need the help of insulin to bring them down to the normal level, between 4 and 8ml, if we have consumed too much. The process of how we get the sugar is from the food we eat, mainly by the carbohydrates we consume. Carbohydrates are taken into the body by the food, and are then digested and changed into glucose that the body can use for energy. During exercise blood sugar levels will fall below our normal, so our body receptors say ‘level of
glucose in the body is too low’ and therefore will tell the pancreas to produce glycogen to bring our sugar levels back up.