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Biology > Homeostasis > Flashcards

Homeostasis Flashcards

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1
Q

What is homeostasis?

A

The maintenance of a constant internal environment

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2
Q

What is the optimum point?

A

The level at which the system works best.

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3
Q

What is a receptor?

A

Detects deviations from the optimum point and informs the coordinator.

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4
Q

What is the coordinator?

A

Co-ordinates information from receptors and sends instructions to the effector.

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5
Q

What is the effector?

A

Brings about changes needed to return to the optimum point.

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6
Q

What is a feedback mechanism?

A

Informs the receptor of changes brought about by the effectors.

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7
Q

What is negative feedback?

A

The corrective measures are turned off as the body has reached the optimum point again.

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8
Q

What is positive feedback?

A

Thee feedback causes the corrective measures to remain turned on, causing the system to deviate further from the optimum.

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9
Q

How does the second messenger model work?

A
  • Adrenaline binds to a receptor in the membrane of a liver cell.
  • Activates the enzyme adenyl cyclase by changing the shape of the receptor inside the cell.
  • Adenyl cyclase converts ATP to cyclic AMP (cAMP)
  • Binds to protein kinase and activates it.
  • Protein kinase converts glycogen into glucose which leaves the liver cell by facilitated diffusion.
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10
Q

What does the pancreas produce?

A

Digestive enzymes and the hormones involved in glucose regulation insulin and glucagon.

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11
Q

What are the islets of Langerhans?

A

Groups of cells in the pancreas which produce hormones, surrounded by cells which produce digestive enzymes.

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12
Q

What are the cells which make up the liver called?

A

Hepatocytes

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13
Q

What is glycogenolysis?

A

The conversion of glycogen to gucose

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14
Q

What is the name for the conversion of glycogen to glucose?

A

Glycogenolysis

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15
Q

What is gluconeagenesis?

A

The production of glucose.

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16
Q

What is the name for the process for the production of glucose?

A

Gluconeagenesis

17
Q

What is glycogenesis?

A

Conversion of glucose to glycogen.

18
Q

What is the name for the conversion of glucose to glycogen?

A

Glycogenesis

19
Q

What 4 things affect the level of glucose in the blood?

A
  • Diet,
  • Glycogenolysis,
  • Gluconeogenesis,
  • Level of physical or mental demand.
20
Q

What cells detect a rise in blood sugar using receptors and how do they respond?

A

B cells, respond by secreting insulin.

21
Q

What happens when body cells bind with insulin?

A
  • Change in the tertiary structure of glucose transport channels, allowing more glucose in,
  • Increases the number of carrier proteins,
  • activation of enzymes that convert glucose into glycogen and fat.
22
Q

How is does insulin binding to a receptor on a membrane increase the number of glucose carrier proteins?

A

Vesicles (made up of the protein in the glucose channels) fuse to the membrane.

23
Q

What do a-cells do?

A

Secrete glucagon into the blood.

24
Q

What causes type one diabetes?

A

The immune system attacks the Bcells in the islets of Langerhans so they cannot produce insulin. Causing hyperglycemia.

25
Q

What causes type two diabetes?

A

Often linked with obesity. B cells don’t produce enough insulin to body cells don’t respond to the insulin properly.

26
Q

Describe ultafiltration in the kidneys.

A

Blood from renal artery enters arteries which go into the Bowman’s capsule. The efferent arteriole carries blood our of the bowman’s capsule and is smaller i diameter than the afferent arteriole. So blood in glomerulus in under high pressure. Liquid is forced through capillary wall, basement membrane and epithelium of Bowman’s capsule. Proteins stay in blood.

27
Q

Which three places does selective re-absorption occur?

A

Proximal convoluted tubule, loop of henle, distal convoluted tubule.

28
Q

Where is the loop of henle located in the kidneys?

A

In the medulla.

29
Q

How does the loop of Henle maintain a sodium ion gradient?

A

Na+ is pumped out of the top of the ascending limp by active transport. Creating a low WP in medulla. As this is lower than the WP in the descending limb water moves out by osmosis. Making the filtrate more concentrated. More Na+ diffuses out due to low WP in bottom of ascending limb

30
Q

How and where is water potential in the blood monitored?

A

By osmoreceptors in the hypothalamus. If the WP in the blood is ow then water moves out the osmoreceptors

31
Q

What detects the signal from the osmoreceptors and how does it respond?

A

The posterior pituitary, secretes ADH (antidiuretic hormone)

32
Q

What does ADH do to the walls of the distal convoluted tubule and colecting duct?

A

Makes the walls more permeable to water by triggering phosphorylase which makes vesicles containing aquaporins to fuse to the cell surface membranes.

Biology (23 decks)

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