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Biology > C15 - Homeostasis > Flashcards

C15 - Homeostasis Flashcards

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1
Q

What is homeostasis

A

Maintaining a constant internal environment despite internal/external changes

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2
Q

Name 4 things we have to control in homeostasis

A

Body temp
ion levels
water levels
glucose levels

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3
Q

What is negative feedback

A

When a response to a change returns the system to the ideal levels

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4
Q

what is positive feedback

A

response to a change that increases the degree of change

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5
Q

What are endotherms

A

Generate heat yourself eg. mammals

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6
Q

What are ectotherms

A

dependant on external heat sources eg. lizards

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7
Q

Describe how an ectotherm maintains its body temperature

A

Behaviours

  • exposing themselves to sun
  • taking shelter
  • gaining warmth from ground
  • colour variations
  • shaking and moving
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8
Q

Describe how an endotherm maintains its body temperature

A

Detection in thermoregulation centre in the hypothalamus and skin temp receptors

Heat gain centre- activated by a fall in blood temp
- causes heat gain
Heat loss centre - activated by a rise in temp
- causes heat loss

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9
Q

What is the role of the liver?

A 
converts lactic acid to glucose
produces bile
metabolism of alcohol and toxins
deamination
disposal of RBCs
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10
Q

What are essential amino acids

A

amino acids we can not synthesise, they are essential to get from our diet

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11
Q

How can non-essential amino acids be synthesised

A

essential amino acids –> (transamination)–> converted to non-essential amino acids

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12
Q

What is the name of the series of reactions that form urea in the liver

A

Ornithine cycle

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13
Q

Name the 3 main blood vessles in the liver

A

Hepatic artery
Hepatic vein
Hepatic portal vein

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14
Q

What is the role of the hepatic artery

A

carries oxygenated blood to the liver

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15
Q

What is the role of the hepatic vein

A

carries deoxygenated blood away from the liver

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16
Q

What is the role of the hepatic portal vein

A

carries blood from the digestive system to liver

blood is deoxygenated and nutrient-rich

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17
Q

Describe the structure of a sinusoid

A

hepatic portal vein and hepatic artery at top of sinusoid
a single layer of cells forming the wall of sinusoid surrounded by hepatocytes
Blood drains through the lumen to hepatic vein

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18
Q

What are Kupffer cells

A

Adapted macrophages

Ingest foreign particles and protect against disease

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19
Q

What are the 3 main vessels in the kidney

A

renal artery
renal vein
ureter

20
Q

Where does urine from the ureter go?

A

ureter –> bladder –> urethra

21
Q

Describe the basic structure of the kidney

A

pelvis in centre
cortex (bark) on outside
medulla on inside
made of nephrons

22
Q

What are the medulla and cortex made of

A

Cortex - Bowmans capsule, convoluted tubules etc.

Medulla - loop of henle, collecting duct

23
Q

What is a group of nephrons called

A

Pyramind

24
Q

Describe the structure of a nephron

A 
(glomerulus feeding into) Bowmans capsule
proximal convoluted tubule
descending limb of loop of henle
ascending limb of loop of henle
distal convoluted tubult
collecting duct
25
Q

Describe the movement of blood through the Bowmans capsule into proximal convoluted tubule

A

Enters glomerulus through the afferent artery and glows through the glomerulus
leaves through the efferent artery

afferent artery wide, efferent artery narrow causes high pressure forces plasma out of glomerulus through basement membrane and podocytes into bowmans capsule and to proximal convoluted tubule

26
Q

What is the role of the basement membrane and podocytes

A

prevents blood cells from leaving

double filter system

27
Q

What happens to filtrate in the proximal convoluted tubule

A

reabsorption of amino acids , glucose, vitamins, hormones

reabsorption of most NaCl and H2O

28
Q

What is osmolarity

A

a measure how how much (moles) of a xolute is dissolved (0 is pure water, higher is more concentrated)

29
Q

Describe how the loop of henle filters water out of the filtrate

A

initially filtrate is isotonic with surroundings
Na and Cl ions actively transported out of ascending limb, osmolarity of interstitial fluid increases
Water moves out descending limb due to osmotic gradient, creating more concentrated filtrate
This replaces the more diluted filtrate in ascending limb
cycle repeats
Filtrate in interstitial space can diffuse into blood vessles

30
Q

How are the nephrons of desert animals adapted?

A

Longer loop of henle - allows more water absorption

31
Q

What happens to filtrate in distal convoluted tubule?

A

Fine tuning of water balance

32
Q

What happens in the collecting duct

A

Takes urine to pelvis and then ureter

33
Q

What sections of nephrons are affected by ADH

A

distal convoluted tubule and collecting duct

34
Q

What is osmoregulation?

A

Maintaining the water balance in your blood within the narrow boundary

35
Q

What is water balance affected by (why many we need osmoregulation)?

A

Water uptake

Solute conc

36
Q

what would happen if the water balance was too high

A

cells would lyse (burst)

37
Q

what would happen if the water balance was too low

A

no transport medium

water is essential for chemical reactions

38
Q

what is ADH

A

Anti Diuretic Hormone

39
Q

When is ADH produced?

A

When you’re All Dried up - when water balance is too low in the blood

40
Q

Where is ADH detected and produced?

A

detected in hypotalamus

produced in pituitary gland

41
Q

What does ADH do

A

Increase the absorption of water into the blood, negative feedback

42
Q

How does ADH effect its target cells?

A

ADH binds to ADH receptor
Secondary messenger cAMP produced
Causes vesicles to fuse to cell surface membrane
Vesicles contain aquaporin
creates pores for water to diffuse through (from urine to interstitial fluid)

43
Q

Names the components of urine

A 
water 
urea
NaCl
Hormones
Metabolites of drugs
44
Q

What are the medical uses of urine

A

Pregnancy testing
DIabetes testing
Detection of drugs/drug metabolites

45
Q

How does haemodialysis work?

A

Blood from veins run through dialysis fluid (that is kept at constant temp)
Dialysis fluid isotonic for hormones, amino acids etc. but contains no urea
Urea diffuses out

Biology (17 decks)

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