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excretion ! Flashcards

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Biology 101 flashcards
1
Q

catabolic reactions !

A

chemical reactions whereby complex substances are broken down into simpler ones

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2
Q

anabolic reactions !

A

chemical reactions which simpler substances are built up into more complex substances

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3
Q

excretion !

A

process by which metabolic waste products & toxic substances are removed from the body

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4
Q

need for excretion !

A

metabolism : produces waste products (CO2, H20, urea) that can harm the body when accumulated

therefore -> need to be removed by excretion

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5
Q

excreted by…

A

skin : sweat
- excess mineral salts + nitrogenous waste products (urea) + excess water

lungs : expired air
- CO2 + water vapour

liver : faeces from intestines
- bile pigments

kidney : urine
- urea + excess H20 + excess salts

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6
Q

urinary system !

A 
kidneys 
ureters
urinary bladder 
urethra
sphincter muscle
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7
Q

kidneys function !

A

remove waste products (excess H20, urea, mineral salts) from blood by urine

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8
Q

ureters function !

A

connects kidneys to bladder

carries urine to bladder

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9
Q

urinary bladder function !

A

stores urine temporarily

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10
Q

urethra function !

A

passage to discharge urine from urinary bladder

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11
Q

sphincter muscle function !

A

controls exit of urine from the urinary bladder

when urinary bladder is full : sensory neurones send nerve impulses to brain

brain : send nerve impulses to sphincter muscle to relax
- urine : flow into urethra & out of the body

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12
Q

kidney tubules !

A

narrow
richly supplied with blood vessles : absorb water, nutrients & mineral salts needed
urine formed

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13
Q

nephron !

A

basic functional unit of kidneys

richly supplied with blood capillaries

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14
Q

nephron flow of blood !

A

renal artery -> afferent arteriole -> efferent arteriole -> glomerulus -> blood capillaries -> renal vein

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15
Q

nephron structure !

A

Bowman’s capusule

glomerulus : dense network of capillaries contained in Bowman’s capsule

proximal convoluted tubule

loop of henlé

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16
Q

urine formation !

A

ultra-filtration

selective reabosrption

17
Q

ultrafiltration !

A

blood passes from branches of renal artery -> glomerulus

caused by high blood pressure generated
- afferent ateriole’s lumen is larger than efferent ateriole -> more blood enters glomerulus than blood leaving -> high pressure -> substances to be forced out of blood

basement membrane around the glomerulus : fine filter
- partially permeable membrane : allowing only small molecules (glucose, amino acids, mineral salts & nitrogenous wastes) can pass through to form filtrate

blood cells, platelets & large molecules (proteins & fats) : remain in the glomerular capillaries

18
Q

ultrafiltration filtrate flow !

A

PCT -> loop of henlé -> DCT -> collecting duct

19
Q

ultrafiltration non-filtrate flow !

A

efferent atery -> blood capillaries -> renal vein

20
Q

selective reabsorption !

A

allows useful susbtances to be reabsorbed back into blood capillaries

  • glucose, amino acids, salts : diffusion & active transport
  • water : osmosis

loop of Henlé : some water reabsorbed into bloodstream from filtrate in tubule
DCT : some salts reabsorbed
collecting duct : water reabsorbed

21
Q

osmoregulation !

A

process whereby amount of water & solute concentrations in blood are controlled to maintain constant water potential in the body

22
Q

ADH

A

controls water potential of blood plasma

  • produced by hypothalamus
  • released by pituitary gland
  • increases permeability of water of the collecting duct
23
Q

importance of constant water potential of blood plasma

A

if too concentrated : RBC -> dehydrate -> crenated

if too dilute : RBC -> absorb water -> expand -> burst

24
Q

excess water in blood

A

large intake of water : water potential in blood plasma increases

stimulates hypothalamus in brain -> pituitary gland secretes less ADH into blood stream

cells in walls of collecting ducts become less permeable to water -> kidney tubules reabsorb lesser water

larger volume of urine produced (more diluted) -> water potential of blood plasma returns to normal level

25
Q

dehydration

A

loss of water : water potential in blood plasma decreases

stimulates hypothalamus in brain -> pituitary gland secretes more ADH into blood stream

cells in walls of collecting ducts become more permeable to water -> kidney tubules reabsorb more water

smaller volume of urine production (more concentrated) -> water potential of blood plasma returns to normal level

26
Q

kidney failure !

A 
high blood pressure
diabetes
alcohol abuse
severe accidents that physically damage kidney
complications from major surgery
27
Q

dialysis machine !

A

mimics function of kidney

  1. blood is drawn from vein in patient’s arm
  2. blood is pumped into dialysis machine through a tubing
  3. tubing : bathed in dialysis fluid & its walls are partially permeable
  4. small molecules (urea & metabolic waste products) : diffuse out of tubing
  5. larger molecules (platelets & blood cells) : remain in tubing
  6. filtered blood is released to a vein in patient’s arm
28
Q

dialysis tubing !

A

walls are partially permeable

  • allows only small molecules (urea) to diffuse out of tubing from bloodstrream
  • big molecules (proteins, blood cells) : remain in tubing

narrow, long, coiled

  • increases surface area to volume ratio -> speeds up rate of exchange of substances between blood & dialysis fluid
  • provides sufficient time for exchange of substances

direction of blood flow : opposite to flow of dialysis fluid
- maintains diffusion gradient for removal of waste products

29
Q

dialysis fluid !

A

contains essential salts for body

  • ensures that these salts do need diffuse of out blood through tubing to dialysis fluid
  • if blood lacks these salts : salts in dialysis fluid can diffuse into blood

concentration of glucose & amino acids are the same as bloodstream

  • prevents glucose & amino acids in blood to diffuse out of blood into dialysis fluid
  • if blood lacks glucose & amino acids, they can enter bloodstream from dialysis fluid

does not contain nitrogenous waste products (urea)
- creates diffusion gradient between dialysis fluid & blood -> allows for nitrogenous waste products (urea) to diffuse out of blood into dialysis fluid

bio ! (13 decks)

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