Homeostasis__ is the maintenance of a __constant internal environment.
Our body has automatic control systems in place which enable our body to maintain its temperature and water at optimum levels. Cells require these optimum levels in order for them to function properly.
If someone does strenuous exercise or is placed in an extreme climate, it will affect homeostasis. The body temperature, blood oxygen levels, hydration __and __salt levels will all be affected. This may then lead to the individual not feeling as well as their body is trying to cope with the change.
Thermoregulation__ __is when the body can maintain its core body temperature at a set value.
The body temperature has a massive effect on the enzyme activity__ __as enzymes work best at specific optimum temperatures, depending on the type of enzyme.
- The outer layer of skin is made of dead cells called epidermis, and it contains sensory nerve endings.
- Under the epidermis is the dermis, and it contains living cells, blood vessels, sweat glands, hair follicles and sensory receptors.
- Under the dermis is the __subcutaneous tissue __that stores lipids.
- The skin is highly important throughout thermoregulation as it acts as a receptor __and an __effector.
The hypothalamus is an area of the brain that contains two sets of thermo receptors, and it receives information about temperature of blood that passes through the brain. This tells the brain about the core body temperature, and it is used to regulate the body temperature.
The skin is also the layer between the cells and the external environment. It is where heat is lost and gained.
When the body is too cold:
- Less blood flows through the capillary beds which are near the surface of the skin.
- This allows more blood to remain in the deeper skin structure, as the arterioles that send blood to the capillary beds become more narrow.
- This is achieved by narrowing the arterioles that supply the capillary beds near the surface (arterioles and arteries have plenty of muscle in their walls that can contract to narrow the lumen of the blood vessel)
- Vasoconstriction is when the arterioles contract.
When the body is too hot:
- On the other hand, vasodilation is when the arterioles relax, so that more blood is flown towards the capillary beds near the surface. This allows more heat to be lost to the external environment.
Osmoregulation__ __controls the water levels and mineral ions in the blood. It is vital to control the water level and the mineral ions - it has to be the same concentration inside and around the cell. This will protect the cell from having too much or too little water.
The __hypothalamus __is a part of the brain that is continuously measuring the __water potential __of blood.
- If the concentration of water is a lot higher on the outside than the concentration of the concentration of water on the inside, water that tries to enter the cell may burst.
- However if the water concentration is a low lower outside in comparison to the inside, water may leave the cell, causing the cell to shrivel.
If animals lose or gain too much water, they do not function properly, or as efficiently.
Insulin__ __is a hormone that is released from the pancreas, and it controls the blood glucose concentration.
- When the blood glucose concentration is too high, the pancreas releases insulin into the bloodstream so that it can reach muscles and liver tissues.
- Insulin will signal to the cells so that it can __absorb the sugar __from the bloodstream.
- Insulin allows the sugar to enter the cell so that energy can be created.
- If there is too much glucose, it is then converted into a storage carbohydrate called glycogen.
However, if the blood glucose concentration is too low, the pancreas will release another type of hormone called glucagon.
- Glucagon causes __glycogen __to be converted into __glucose __so that the concentration of glucose can be higher in the bloodstream.
Type 1 Diabetes is when the pancreas cannot produce enough insulin.
As a result, when someone with type 1 diabetes has a meal, their blood sugar level rises. By controlling the individual’s diet, monitoring their blood sugar level and injecting insulin, they are able to use the sugar for energy.
Type 2 diabetes is when the liver cells produce insulin, but_ the body does not respond to it_.
It can be treated through a change in diet, medication, and insulin injections.
BMI and Diabetes
There is a correlation between those who are overweight and those who develop type 2 diabetes. Scientists have also found that those with more weight around their waist are more likely to develop type 2 diabetes.
It is useful to use BMI and waist:hip calculations to monitor an individual’s weight gain so that they can have a smaller chance of developing type 2 diabetes.
Body mass index (BMI) is used to show if a person is a healthy mass for their height.
The equation is: BMI = mass/(height)2
Here are the accepted BMI ranges that are commonly used by professionals:
- Underweight: under 18.5 kg/m2
- Normal weight: 18.5 to 25 kg/m2
- Overweight: 25 to 30 kg/m2
- Obese: over 30 kg/m2
Waist:hip ratio = waist measurement/hip measurement.
A waist:hip ratio of over 0.85 in women and 1 in men is considered an indicator of obesity.
- How can type 2 diabetes be treated?
- Your answer should include: Diet / Medication / Insulin / Injections
- Where is insulin released from, and what is its function?
- Your answer should include: Pancreas / Blood / Glucose / Concentration
Explanation: Insulin is a hormone that is released from the pancreas, and it controls the blood glucose concentration.
- What is the hypothalamus’ role in homeostasis?
- Your answer should include: Brain / Thermoreceptors / Temperature / Blood
Explanation: Hypothalamus is an area of the brain that contains two sets of thermoreceptors, and it receives information about temperature of blood that passes through the brain. This tells the brain about the core body temperature, and it is used to regulate the body temperature.