3.3 Homeostasis Flashcards Preview

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Flashcards in 3.3 Homeostasis Deck (47)
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What is homeostasis?

Maintenance of a constant internal environment


Why is homeostasis important? Which components?

Body temperature: enzymes
Blood sugar levels: respiration and blood pressure
Water: cell size
pH: enzymes


What waste products are removed from our body?

Carbon dioxide


How and why are the two waste products removed?

Carbon dioxide: breathed out via the lungs because it makes carbonic acid lowing the pH of our blood affecting enzymes

Urea: made in the liver from the breakdown of excess amino acids, removed by the kidneys in urine, temporarily stored in the bladder
Because it is toxic


What is negative feedback?

A deviation from the norm initiates corrective mechanisms to restore the norms


How is water obtained in the body?

When eating and drinking


How do we lose water?

Breathing out


What can too much or too little water do to out cells?

Damage them causing them to burst or shrivel


What do kidneys do?

Filter the blood excreting substances you don't want and keep substances the body needs


How is blood brought to the kidney?

Via the renal artery


What is a nephron?

Microscopic filtering units


What is the first stage of the kidney producing urine?

Filtering the blood:
The Glomerulus separates the larger molecules - red blood cells, white blood cells and carbon dioxide
From the smaller molecules - water, ions, urea, glucose and amino acids
The bowman's capsule collects the filtrate of smaller molecules and they can pass through the renal tubial


What is the second stage of the kidney producing urine?

Reabsorbing all the sugar:
In the proximal convoluted tubal glucose and amino acids are reabsorbed by active transport as they ate against a concentration gradient

Lots of mitochondria and ribosomes- for energy and proteins (they carry certain molecules across a membrane)


What is the third stage of the kidney producing urine?

Reabsorbing dissolved ions needed:
In the loop of Henle some ions are reabsorbed by active transport
But other salts are left behind to balance what the body needs


What is the fourth stage of the kidney producing urine?

Reabsorbing as much water as the body needs:
In the distal convoluted tubal a diuretic hormone is released by the pituitary gland leading to increased reabsorption of water via osmosis


What is the fifth stage of the kidney producing urine?

Releasing urea, excess ions and water:
In the collecting duct the molecules left are water, salt and urea forming urine to be temporarily stored in the bladder leaving via the ureter


What can Kidney failure be treated with?

Kidney dialysis
Kidney transplant


What does dialysis do?

Remove the blood from you body then clean out the urea before sending it back


What is an anticoagulant used for in dialysis? Example of drug?

Prevents blood clotting



What is an air trap used for in dialysis?

Gets rid of air bubbles preventing air embolisms (blood vessels blockages due to air bubbles)


What is done to maximise amount of urea moved in the dialysis fluid?

The dialysis fluid flows in the opposite direction to the blood


How is urea removed in dialysis?

Urea moves out of the blood via diffusion as there is no urea in the dialysis fluid creating a concentration gradient


How do you not lose useful molecules in dialysis?

The fluid contains the same concentration of glucose and mineral ions as the blood so there is no no net movement of the substances needed by the body


How often is dialysis done?

Carried out regularly
Changes from person to person


What are some similarities between dialysis and a nephron?

Both remove urea
Red blood cell and white blood cells don't leave the blood


What are some differences between dialysis and a nephron?

Glucose is removed and then reabsorbed by active transport from the blood in the nephron


What are the advantages of dialysis?

Prevents you feeling ill
Available to all kidney patients
No immunosuppressant drugs


What are the disadvantages of dialysis?

Time consuming
Affects your daily life
Go to hospital al lot
Can't eat salt and protein in between


What does a kidney transplant do?

Enables a diseases kidney to be replaced with a healthy one from a donor (dead or living)


What are antigens?

Proteins on the surface of cells