Communication and Homeostasis

Question 1

Why is homeostasis important?

Answer 1

• Maintains a constant internal environment for metabolic reactions
• Allows cells to function normally and avoid damage
• Helps organisms respond and adapt to external changes

Question 2

What is the name of a liver cell and what does it contain?

Answer 2

• Hepatoctye
• Contains a large nuclei, a prominent golgi apparatus, and several mitochondria

Question 3

What is the role of the liver in carbohydrate metabolism?

Answer 3

• Hepatocytes in the liver convert glucose to glycogen when blood glucose levels rise
• And vice versa

Question 4

What is the role of the liver in detoxification (removal of waste products)?

Answer 4

• Detoxifies hydrogen peroxide - hepatocytes contain catalase
• Detoxifies alcohol - hepatocytes contain enzyme alcohol dehydrogenase which breaks down ethanol to ethanal, which is then converted to ethanoate
• Detoxifies ammonia - ornithine cycle converts ammonia into urea

Question 5

What is the ornithine cycle?

Answer 5

Set of enzyme controlled reactions during which ammonia reacts with carbon dioxide and is converted to urea

Question 6

What are the main blood vessels associated the nephron?

Answer 6

• Afferent arteriole - supplies glomerulus with blood
• Glomerulus - mass of capillaries from which fluid is forced out of the blood into the Bowman’s capsule
• Efferent arteriole - carries blood away from the glomerulus
• Capillaries around the PCT, DCT and loop of Henle - absorb salts, glucose and water

Question 7

How is a high hydrostatic pressure formed within the glomerulus?

Answer 7

The diameter of the afferent arteriole is greater than the diameter of the efferent arteriole

Question 8

How do the endothelial cells in the glomerulus help with ultrafiltration?

Answer 8

The endothelial cells have pores between them that allow water, glucose and mineral ions to be squeezed out of the capillary to form glomerular filtrate

Question 9

What is the role of the posterior pituitary gland in osmoregulation?

Answer 9

• The posterior pituitary gland stores ADH that has been produced by osmoreceptors in the hypothalamus
• When stimulated, the posterior pituitary gland secretes ADH into capillaries so it can be transported to kidneys

Question 10

What is GFR, and how can it be measured?

Answer 10

• Measure of how much blood is filtered in the bowman’s capsule’s of the nephrons
• A blood test measured the level of creatinine in the blood, which is used to estimate GFR
• High level of creatinine may indicate kidney disease, and a GFR of below 15 indicates kidney failure

Question 11

What can happen if they kidneys fail?

Answer 11

• Build up of mineral ions in the blood - causes a loss of electrolyte balance and osmotic imbalances
• Build up of toxic urea in cells - can poison cells
• High blood pressure - can cause heart problems and strokes

Question 12

How are drugs like anabolic steroids detected in the urine?

Answer 12

• By vaporising the urine sample with a known solvent
• It is then passed along the tube for gas chromatography and mass spectrometry
• This often follows an immunoassay (monoclonal antibody shit) to confirm the presence of the drug