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BIOLOGY A2 > HOMEOSTASIS > Flashcards

HOMEOSTASIS Flashcards

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1
Q

What does homeostasis do?

A

Ensures the bodies internal environment is continuously in a steady state.

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2
Q

What does homeostasis regulate?

A

body temperature (preventing denaturation), blood pH, water content of blood, blood glucose levels.

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3
Q

What is osmoregulation?

A

regulates the water potential of the blood. Uses negative feedback, Any changes in condition cause a corrective mechanism to start.

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4
Q

What does osmoregulation prevent?

A

It prevents lysis or crenation of cells.

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5
Q

What is the corrective mechanism that starts when a change occurs in the body?

A

Conditions in the body change from set point - change detected - corrective mechanisms activated - conditions returned to set point - corrective mechanisms switched off.

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6
Q

What is the kidney involved in?

A

Excretion and osmoregulation (water potential of the body).

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7
Q

What do the kidneys remove from the body?

A

Urea and creatinine.

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8
Q

What are the structures of the nephron?

A

Bowmans capsule, proximal convoluted tubule, loop of henle, distil convoluted tubule.

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9
Q

What are the 2 stages of urine production?

A

Ultrafiltration, reabsorption.

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10
Q

Briefly explain ultrafiltration?

A

Glomerular plasma filtered at high pressure, filtrate contains useful and toxic substances.

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11
Q

Briefly explain reabsorption?

A

The useful substances are reabsorbed into the blood after ultrafiltration.

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12
Q

What does the Bowmans capsule consist of?

A

2 layers (epithelium (outer) and squamus endothelium (inner))

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13
Q

What are podocytes?

A

They are footed cells that make up the epithelial lining in the bowmans capsule, the third layer of filtration.

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14
Q

What is podocytes role in the bowmans capsule?

A

Preventing plasma proteins entering the ultrafiltrate due to filtration slits.

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15
Q

What is the basement membrane?

A

It is the effective filter and determine what components of the blood enter the bowmans capsule. It acts as a plasma barrier.

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16
Q

What is negative feedback?

A

It is when a factor is returned to its normal resting state the corrective measures are turned off.

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17
Q

How is the bowmas capsule supplied with blood?

A

It is supplied with blood from an afferent arteriole.

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18
Q

How does the blood leave the bowmans capsule?

A

Efferent arteriole.

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19
Q

What is the glomerulus?

A

It is a tightly coiled knot of cappilaries.

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20
Q

What does the bowmans capsule extend into?

A

Extends into the proximal convolulated tubule.

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21
Q

What does the proximal convulated tubule extend into?

A

The loop of henle.

22
Q

Where does the loop of henle extend down into?

A

The medulla of the kidne.

23
Q

Where does the loop of henle extend down into?

A

The medulla of the kidney.

24
Q

What does the loop of henle become?

A

It joins into the distal convuluted tubule.

25
Q

What does the dital convuluted tubule join to?

A

It joins to the collecting duct?

26
Q

What isthe collecting ducts job?

A

It empties its contents into the ureter which takes the urine to the bladder.

27
Q

What is the proximal convulated tubule does?

A

It is used for reabsorption.

28
Q

How is the proximal convulated tubule adapted for reabsorption?

A

It is lined with epithelial cells containing microvilli which increases the surface area allowing for better reabsorption and numerous mitochondria with iprovides ATP necessary ofr active transport.

29
Q

What is another way that substances can be reabsorbed before active transport takes place?

A

They can also be absorbed by facilitated diffusion as long as the concentration gradient permits.

30
Q

What is one way that small proteions can be reabsorbed?

A

By pinocytosis, they are digested and diffused.

31
Q

What is the loop of henle used for?

A

The loop of henle is used for the formation of as salt bath.

32
Q

Explain what a salt bath is?

A

It is when the tissue fluid in the medulla hypertonic, compared to the nephron filtrate.

33
Q

Why is the formation of a salt bath useful?

A

It allows water ti be reabsorbed back into the blood stream.

34
Q

How is a salt bath formed?

A

Done by pumping sodium and chloride out of the filtrate into the surounding tissue.

35
Q

Explain the descending limb?

A

It is impereable to ions but some water leaves by osmosis. (The filtrate is more concentrated in the descending limb)

36
Q

Explain the ascending limb?

A

pumps sodium and chloride into the filtrate surrounding the tissue. (permeable to water)

37
Q

Explain what the distil convulated tubule does?

A

It is used for homeostasis.

38
Q

Explain homestasis?

A

It is the maintenence of conmstant or steady state conditions of the internal environment in the body.

39
Q

What are the three basic features of homesostasis?

A

Control system with sensors, corrective mechanism and negitive feedback system.

40
Q

Explain what a control system is in relation to homeostasis?

A

Sensor (receptor) that moniters the factor being controlled, the receptor can be nervous or hormonal.

41
Q

Explain the corrective mechanism in relation to homeostasis?

A

brings about changes resulting in a regulation of this factor.

42
Q

Explain the negative feedback system in relation to homeostasis?

A

It stops corrective mechanisms and prevents over-correction.

43
Q

How is the distal convulated tubule adapted for active transport?

A

It has microvilli brushed border with membrane pumps to allow active trasnsport.

44
Q

What hormone is homesostaisis regulated by?

A

ADH hormone.

45
Q

In the descending limb of the loop of henle what is the filtrate?

A

The filtrate becomes progressively more concentrated as you go down the limb and when you reach the bottom it is hypertonic to the blood.

46
Q

What is the filtrate in the ascending limb of the loop of henle?

A

Because of the ions leaving the ascending limb the filtrate becomes more and more dilute, it is hypotonic by the time it reaches the top of the ascending limb.

47
Q

What happens if the blood becomes too concentrated?

A

blood solute potential becomes more negative, body releases more ADH into blood, causes collecting ducts to become more permeable, therefore more water is absorbed, smaller volume of more concentrated (hypertonic)urine, negative feedback.

48
Q

What is osmoregulation?

A

It is the control of water potential of bodily fluids.

49
Q

Explain osmoregulation?

A

Controlled my hypothalamus, osmoreceptor cells detect changes in blood passing through brain, ADH released from puititary gland, ADH targets endothelial cells on collecting ducts on nephrons, water molecules cross aquaporins, ADH increases permeability of convoluted tubule.

50
Q

What happens when the solute potential falls?

A

increased ADH, kidney reabsorbs water, concentrated urine.

51
Q

What happens when solute potential falls?

A

decreased ADH secretion, kidney reabsorbs less water, dilute urine.

BIOLOGY A2 (3 decks)

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