Biology Fashcards 2

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What is homeostasis?
The maintenance of a constant internal temperature.
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What are the 6 main things that need to be controlled in homeostasis?
Body temperature, water content, ion content, bloody sugar levels and urea.
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What part of the human body acts as a 'personal thermostat'?
The thermoregulatory centre in the brain. IT contains receptors that are sensitive to blood temperature flowing through the brain and it also receives impulses from the skin.
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What happens when your body is too HOT?
Hairs lie flat, sweat is produced by sweat glands and evapourates from the skin (removing heat), the blood vessels supplying the skin dilate so more blood flows close to the surface of the skin, therefore it is easier for heat to be transferred.
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What happens when your body is too COLD?
Hairs stand up to trap an insulating layer of air, no sweat is produced, blood vessels constrict to close off skins blood supply, you shiver (contract muscles) which needs respiration which releases energy to warm the body.
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What do kidneys act as?
Act as filters to clean the blood.
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What are the three main roles of the kidneys?
Removal of urea from the blood, adjustment of ions in the blood, adjustment of water content of the blood.
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How is urea produced?
When any excess amino acids are converted into fats and carbohydrates which can be stored. This process occurs in the liver and urea is a waste product from the reaction.
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Where does the liver release the urea?
The bloodstream, for the kidneys to filter.
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How are excess ions removed?
By the kidneys and in sweat (such as sodium ions)
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What are the three main ways water is lost from the body?
Urine, sweat and through the air we exhale.
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Why do sports drinks contain water, sugar and ions?
The water and ions (i.e sodium) replace those lost in sweat, and the sugar replaces the sugar used up by muscles during exercise.
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What are nephrons?
Filtration units in the kidneys.
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Describe the process of ultrafiltration.
A high pressure is built up wich squeezes water, urea, ions and sugar out go the blood and into the Bowmans capsule. Then the membranes between the blood vessels and BC act like filters so large molecules stay in the blood.
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Where does reabsorption occur?
In the nephron.
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Describe reabsorption.
All sugar ( and useful substances) is reabsorbed via active transport against the concentration gradient as liquid flows along the nephron. Sufficient ions and water are reabsorbed, excess ions arent.
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Where does urea go after it exits the nephron?
To the ureter and to the bladder as urine.
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Other cards in this set

Card 2

Front

What are the 6 main things that need to be controlled in homeostasis?

Back

Body temperature, water content, ion content, bloody sugar levels and urea.

Card 3

Front

What part of the human body acts as a 'personal thermostat'?

Back

Preview of the front of card 3

Card 4

Front

What happens when your body is too HOT?

Back

Preview of the front of card 4

Card 5

Front

What happens when your body is too COLD?

Back

Preview of the front of card 5
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