What is homeostasis?
The maintenance of a constant internal environment
The maintenance of a person's body (internal and external)
What are the things that need to be controlled in our body?
Blood sugar levels
What is the temperature at which enzymes work best?
Why is it important to control our body's water content?
Too much water could move into or out of our cells which will damage the cells.
Too much water could move into the cells making us over-hydrated and the cells won't work as well.
Not enough water could move into the cells meaning that they will get dehydrated and won't work as well.
If the ion (or water) content of the body is wrong, it could upset the balance between ion and water. Why is this?
Too much/too little water is drawn in by osmosis > damages the cells
Too much/too little water is drawn in by diffusion > damages the cells
Too much/too little water is drawn in by active transport > damages the cells
What are the two waste products of our body that need to be controlled?
How is CO2 removed from the body?
By the lungs
By the liver
By the windpipe
Where does urea come from?
The reactions from the conversion of excess amino acids to fats and carbohydrates
The excess products from our food that we consume
Urea is made from excess amino acids and is made in the liver
Urea is not poisonous and is released into the bloodstream by the kidney
What organ filters the blood?
How is urea removed from the body?
Filtered from the blood by the kidneys > temporarily stored in the bladder > excreted from the body in urine
Filtered from the blood by the liver > temporarily stored in the small intestine then to the large intestine > excreted through faeces
How do ions enter the blood?
Taken in by what we drink and then absorbed into the blood
Taken in by the food we eat and then absorbed into the blood
Taken in by what we eat and drink and then absorbed into the blood
Excess ions are removed by the liver
How are some ions also lost?
The kidneys also adjust the water content of the blood to keep it controlled
Water is taken into our body as food and drink. How is it lost?
We can control how much water is lost through breathing
We can control our water content through how much is consumed, sweated out and the amount that is excreted by kidneys in urine
When our body gets too hot...
Hairs lie flat
Hairs stand up (to trap insulating layer of air)
Sweat is produced, evaporating heat from the body
No sweat is produced
Blood vessels supplying the skin dilate
Blood vessels supplying the skin constrict
Our muscles constrict (shivering)
When our body gets too cold...
On a cold day...
We sweat and have more urine (pale coloured and dilute)
We sweat and have less urine (dark coloured and concentrated)
We don't sweat and have more urine (pale coloured and dilute)
We don't sweat and have less urine (dark coloured and concentrated)
On a hot day...
Sports drinks are good to consume because they replace water, sugar and ions that are used up during exercise