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Biology > Homeostasis > Flashcards

Homeostasis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is homeostasis?

A

Physiological control systems that regulation and maintain internal conditions

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2
Q

Why is it important to maintain temp and pH?

A

So enzymes don’t denature and respiration and metabolic reactions can occur

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3
Q

What is pH?

A

A negative logarithmic scale

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4
Q

How is pH calculated?

A

pH = -log[H+]

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5
Q

When do cells crenate?

A

If blood glucose levels get too high then the water will move out of cells by osmosis causing them to shrivel

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6
Q

How do you calculate hydrogen ion concentration from pH?

A

10^-pH

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7
Q

How does negative feedback occur?

A

Receptor, coordinator and then effector

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8
Q

What detects the rise in temperature?

A

Thermoregulatory centre in the hypothalamus

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9
Q

What happens after the temp rise is detected?

A

Nervous system and hormonal system carry signals to skin, liver and muscles

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10
Q

How do we reduce body heat?

A

Sweat, hairs lie down and vasodilation

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11
Q

How do we generate heat?

A

Vasoconstriction, shivers (rapid muscular contraction) , hairs stand to trap insulating air

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12
Q

Why do some stimuli have multiple negative feedback systems?

A

More control and more rapid response

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13
Q

What are two negative feedback systems that control blood glucose?

A

Secrete more insulin and secrete less glucagon

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14
Q

What are some examples of positive feedback mechanisms?

A

Oxytocin during childbirth and blood clotting

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15
Q

What factors influence blood glucose concentration?

A

Diet and exercise

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16
Q

What are islets of langerhans?

A

Groups of cells containing alpha and beta cell, which detect changes in blood glucose and produce insulin/glucagon

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17
Q

What type of cell produces insulin?

A

Beta

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18
Q

What type of cell produces glucagon?

A

Alpha

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19
Q

What do pancreatic ducts do?

A

Carry hormones and enzymes to where they need to be

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20
Q

What does insulin do when it’s produced?

A

Bind to receptors on liver and muscle cells, glucose transport proteins open and glucose enters the cell, additional transport proteins are added to the membrane from vesicles

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21
Q

What happens once glucose enters the cell?

A

Glycogenesis, rate of respiration increased and glucose in converted to triglycerides

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22
Q

What is glycogenesis?

A

Enzymes are stimulated to convert glucose into glycogen

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23
Q

What does glucagon do once produced by the alpha cells?

A

Binds to receptors on liver cells only

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24
Q

What processes does glucagon cause?

A

Glycolysis and gluconeogenesis

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25
Q

What does glycolysis do?

A

Glycogen is broken down into soluble glucose and it enter the blood

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26
Q

What is gluconeogenesis?

A

Glycerol and amino acids are converted into glucose, which then enter the blood

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27
Q

What are the risk factors of type 1 diabetes?

A

Auto immune response, genetics

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28
Q

What can be a cause of type 2 diabetes?

A

Glycoprotein insulin receptors on cells reducing in number, being less responsive to insulin, or not enough insulin being produced

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29
Q

How is type 2 diabetes controlled?

A

Diet, exercise and the use of drugs

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30
Q

What do drugs for type 2 diabetes do?

A

Stimulate insulin production or slow the rate of glucose absorption

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31
Q

What does Adrenalin do?

A

Increases BGC to make more glucose available for muscles to respire to get the bod y ready for action during stress or exercise

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32
Q

Where are the adrenal gland found?

A

On the kidneys

33
Q

Where does Adrenalin go once it’s been released?

A

Binds to specific Adrenalin receptors on plasma membranes of liver cells

34
Q

What does Adrenalin activate?

A

Glucagon secretion and glycogenolysis

35
Q

What does Adrenalin inhibit?

A

Insulin secretion and glycogenesis

36
Q

What happens after Adrenalin has bound to receptors?

A

Adenylate cyclase is activated which converts ATP to cAMP

37
Q

What does cAMP do?

A

Acts as a secondary messenger, an enzyme is activated which breaks down glycogen to glucose

38
Q

What does cAMP stand for?

A

Cyclic adenosine monophosphate

39
Q

What is hypertonic?

A

When the water potential of the blood is lower than the RBC, so water moves out by osmosis causing them to shrink

40
Q

What vein and artery carry blood between the kidneys and heart?

A

Vena cava and aorta

41
Q

What does the ureter do?

A

Carry fluids from the kidneys to the bladder

42
Q

What do the sphincter muscles do?

A

Hold the bladder closed under voluntary control

43
Q

What happens to the renal artery and vein when they reach the kidneys?

A

Branches into smaller vessels

44
Q

What is a nephron?

A

Functional unit of the kidney, where osmoregulation occurs

45
Q

What structures form a nephron?

A

Bowman’s Capsules, affluent and effluent renal artery, glomerulus, proximal convoluted tubule, distal convoluted tubule and Loop of Henle

46
Q

What is the fibrous capsule?

A

An outer membrane that protects the kidney

47
Q

What is the cortex?

A

A lighter coloured outer region made up of renal capsules (Bowmans), convoluted tubules and blood vessels

48
Q

What is the medulla of the kidney?

A

A darker coloured inner region made up of loops of Henle, collecting ducts and blood vessels

49
Q

What’s the renal pelvis?

A

A funnel shaped cavity that collects urine into the ureter

50
Q

What is the structure of the renal capsule?

A

The closed end at the start of the nephron, it is cup shaped and surrounds a mass of blood capillaries known as the glomerulus, the inner layer of the renal capsule is made up of specialised cells called podocytes

51
Q

What is the structure of the proximal convoluted tubule?

A

A series of loops surrounded by blood capillaries, it’s walls are made of epithelial cells which have microvilli

52
Q

What is the structure of the Loop of Henle?

A

A long, hairpin loop that extends from the cortex into the medulla of the kidney and back again, it is surrounded by blood capillaries

53
Q

What is the distal convoluted tubule?

A

A series of loops surrounded by blood capillaries, it’s walls are made of epithelial cells, but it is surrounded by fewer capillaries than the proximal tubule

54
Q

What is the structure of collecting ducts?

A

A tube into which a number of distal convoluted tubules from a number of nephrons empty, it is lined by epithelial cells and becomes increasingly wide as it empties into the pelvis of the kidney

55
Q

What does the afferent arteriole do?

A

A tiny vessel that ultimately arises from the renal artery and supplies the nephron with blood, the afferent arteriolar enter the renal capsule of the nephron where it forms the glomerulus

56
Q

What does the glomerulus do?

A

A many-branched knot of capillaries from which fluid is forced out of the blood, the glomerular capillaries recombine to form the efferent arteriole

57
Q

What does the efferent arteriole do?

A

A tiny vessel that leaves the renal capsule , it has a smaller diameter than the afferent arteriole and so causes an increase in blood pressure within the glomerulus, the effects arteriole carries blood away from the renal capsule and later branches to form the blood capillaries

58
Q

What do the blood capillaries do at the kidney?

A

Reabsorb mineral salts, glucose and water, these capillaries combine to form venules that in turn from together to form the renal vein

59
Q

What are the four stages that the nephrons go through?

A

The formation of glomerular filtrate by ultrafiltration
Reabsorption of glucose and water by proximal convoluted tubule
Maintenance of a gradient of sodium ions in the medulla by the loop of Henle
Reabsorption of water by the distal convoluted tubule and collecting ducts

60
Q

What happens in ultrafiltration?

A

Blood enters glomerulus at high pressure, the efferent arteriole is narrower than the afferent arteriole and this helps to maintain high pressure
Water and smaller components of blood are forced out into the lumen of the nephron forming the glomerular filtrate

61
Q

What are the 3 layers to the filtration barrier?

A

Fenestrated endothelium, basement membrane and podocyte cells

62
Q

What does the fenestrated endothelium do?

A

A capillary wall with large pores to allow plasma through

63
Q

What is the basement membrane and what does it do?

A

Extracellular protein mesh only allows proteins 68,000 daltons or smaller through

64
Q

What do podocyte cells do?

A

Wrapped around the glomerulus they help with filtration and support the glomerulus

65
Q

What is reabsorbed in the proximal convoluted tube?

A

All the glucose and amino acids, some mineral ions, water and urea

66
Q

What are the first steps to reabsorption?

A

Sodium is actively transported out of the cell by the sodium-potassium pump, it’s carried away by the blood, glucose and amino acids are passively taken up by co-transport with sodium into the epithelium cells, this lowers the water potential inside the epithelium cells and so water moves in by osmosis

67
Q

What are the last steps in reabsorption?

A

Urea is reabsorbed by diffusion to dynamic equilibrium, glucose and amino acids leave the cell by facilitated diffusion ad are reabsorbed into the blood, water leaves the cell and moves back to the bloodstream by osmosis, other minerals travel through the epithelial cell and into the blood by facilitated diffusion

68
Q

What’s the structure of the Loop of Henle?

A

Filtrate from PCT comes down the descending limb (permeable to water) it then moves up the thick ascending limb (impermeable to water but highly permeable to solutes), this then leads into the distal convoluted tube, the Loop of Henle is surrounded by Vasa recta

69
Q

What does the vasa recta do?

A

Carries blood from the glomerulus which will reabsorb water and mineral ions

70
Q

What happens in the descending limb of the Loop of Henle?

A

As the filtrate passes down it loses water by osmosis and becomes more concentrated, water is absorbed by the vasa recta and at the bottom of the loop, the filtrate and tissue fluid are in equilibrium

71
Q

How is osmotic gradient maintained in the descending limb?

A

The mineral ion concentration in the tissue fluid increases as you move down the medulla

72
Q

What happens in the thin ascending limb?

A

Na+ and Cl- move out by facilitated diffusion, helping to maintain the concentration gradient

73
Q

What happens in the thick ascending limb?

A

Na+ and Cl- are now being actively transported out, this increases the ion concentration in the medulla and the water potential in the filtrate, some will be reabsorbed by the blood

74
Q

What happens to the filtrate after it moves out of the loop of Henle?

A

It moves through the distal convoluted tube and then into the collecting duct, where any final water is reabsorbed, the amount depends on ADH

75
Q

Where is ADH produced?

A

Int he posterior pituitary gland within the hypothalamus

76
Q

What does the hypothalamus do?

A

Contains osmoreceptors that detect the osmotic pressure of the blood, then it stimulates or prohibits the production of ADH

77
Q

What does ADH do?

A

Increases permeability of the collecting duct to water so increased water reabsorption into vasa recta

78
Q

How does ADH make the distal convoluted tubule and the collecting duct more permeable?

A

Releases aqua porins which are stored in the vesicles of the cells lining the collection duct

Biology (22 decks)

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