B3.3 Homeostasis Flashcards
(35 cards)
Define homeostasis.
The maintenance of a constant internal environment
What are the three main roles of the kidney?
- Removal of urea
- Adjustment of ion content
- Adjustment of water content
How does carbon dioxide leave the body?
Through the lungs when you exhale
How is carbon dioxide produced in the body?
As a product of respiration
Where is urea produced?
The liver
How is urea produced?
- Excess amino acids are broken down into fats and carbohydrates (the body can’t store proteins)
- Urea is a waste poisonous product of this reaction
How does urea leave the body?
- Stored temporarily in the bladder as urine
- Is excreted from the body
What are six things the body has to regulate?
- Body temperature
- Glucose levels
- Ion content
- Water content
- Carbon dioxide removal
- Urea removal
Where do ions (e.g sodium) enter the body?
In the food we eat
What happens if ion/water content is wrong?
The balance between ions and water will be upset, causing too much or too little water to be draw into body cells by osmosis.
Name 3 ways water is lost.
- Urine - Sweat - Air we breathe out
When we sweat little, what is the urine produced by our bodies like?
- Dilute and pale
- Lots of it
When we sweat a lot, what is the urine produced by our bodies like?
- Minimal
- Dark coloured and concentrated
Describe the process in the kidneys.
1) Ultrafiltration. High pressure squeezes glucose, ions, water and urea out of the blood (that entered through the renal artery) and into the Bowman’s capsule.
2) Reabsorption. These molecules travel along the nephron which reabsorbs all glucose and some ions and water into the blood
3) Waste molecules are carried out of the nephron to the bladder where they are temporarily stored before excretion.
What are nephrons?
Filtration units in the kidneys
Why does the body need to control temperature?
Enzymes work best at 37 degrees C.
If temperature is too hot/cold it will cause enzymes to stop working and important reactions will be disrupted,
What part of the brain detects temperature change?
The thermoregulatory centre
How does the thermoregulatory centre detect temperature change?
- Receptors in the brain sense the temperature of the blood flowing through it.
- Receptors in the skin send impulses to the brain when the skin temperature changes.
What happens when temperature increases too much?
- Sweat increases (evaporation cools skin)
- Hair lies flat
- Vasodilation (vessels wider and closer to the skin surface)
What happens when temperature decreases too much?
- Hairs stand up (insulating layer)
- Vasoconstriction (vessels thinner and move deeper)
- Minimal sweating
- Shivering - contracting muscles respire - releasing energy
What organ controls and monitors blood glucose?
The pancreas
Describe the process when there is too much glucose in the blood.
- Insulin secreting cells in the pancreas are stimulated
- Insulin is secreted
- Insulin stimulates glucose uptake from the blood
- Glucose is stored as glycogen in the liver
Describe the process when there is too little glucose in the blood.
- Glucagon secreting cells in the liver are stimulated
- Glucagon is secreted
- Glucagon stimulates the liver breakdown of glycogen into glucose
What is type 1 diabetes?
A disease in which a person’s blood concentration level may rise to a high level because the pancreas doesn’t produce enough insulin.
