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bio > 5.1.2 excretion as an example of homeostatic control > Flashcards

5.1.2 excretion as an example of homeostatic control Flashcards

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Biology 101 flashcards
1
Q

excretion defintion

A

removal of metabolic waste from the body

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2
Q

importance of removing metabolic wastes?

A
  • eg urea, CO2
  • part of homeostasis and maintaining metabolism
  • toxic if accumulates in the body. alter pH, and can act as enzyme inhibitors
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3
Q

3 main metabolic waste products

A

co2
bile pigments
urea

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4
Q

role of lungs in excretion

A
  • CO2 produced as waste product of respiration
  • diffuses from respiring tissues into bloodstream, trnasported MOSTLY AS HCO3- to the lungs
  • diffuses into alveoli to be exhaled
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5
Q

role of skin in excretion

A

sweat contains urea, salts, uric acid, water, ammonoia

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6
Q

name of 3 blood vessels in liver

A
  • hepatic vein
  • hepatic portal vein
  • hepatic artery
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7
Q

hepatic vein

A
  • takes the DEOXYGENATED blood from the liver, joins the vena cava and back to lungs to be oxygenated
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8
Q

how to idnetify hepatic vein in histology

A

LARGEST LUMEN

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9
Q

hepatic artery

A
  • oxygenated blood goes from heart to aorta to liver via here
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10
Q

hepatic portal vein

A
  • DEOXYGENATED blood from the digestive system carrying digestive (someties toxic) products
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11
Q

need for oxygen

A
  • aerobic respiratoin
  • last electron accepter in ox phos
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12
Q

bile duct

A

carried bile from liver to gall bladder

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13
Q

interlobular vessel is …

A

branch of hepatic vein (central vein)

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14
Q

sinusoid

A

blood capillary connecting the ha and hpv to hepativ vein

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15
Q

features of hepatocytes

A

-MULTIPOTENT, so liver can repair itself
- microvilli
- large nucleis
- lots of golgi
- lots of mitochonrdira

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16
Q

KUPFFER CELLS

A
  • macrophages that move within sinusoids
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17
Q

primary function of kupffer cells

A
  • phagocytose erythrocytes
  • digest Hb, made of the haem and protein
  • protein goes to AA
  • haem goes to IRON (goes to bone marrow and used to produce RBC) and bilirubiin (bile pigments) which are used to produce bile
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18
Q

production of bile

A
  • bile released into bile CANNALICULUS
  • goes to BILE DUCT
  • transports bile to gall bladder
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19
Q

purpose of bile

A

EMULSIFICATION and NEUTRALISATION of digested material entering small intestine

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20
Q

function of liver: storage of glycogen (and discuss benefits of glycogen)

A
  • stores glucose in the form of glycogen
  • glycogen is: compact, insolubel so doenst affect water potential, and many branched ends for enzymes to attach to the break down fast
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21
Q

formation of urea

A
  • excess amino acids
    DEAMINATION:
    amino acid + oxygen = ammonia + keto acid
    ORINITHINE CUCLE: NH3 and co2 to form UREA amd water
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22
Q

role of liver: hydrogen peroxide

A
  • catalase enzyme breaks it down into water and oxygen
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23
Q

role of liver: alcohol

A
  • alcohol dehydrogenase converts ethanOL to ethanAL
  • ethanal dehydrogenase converts ethanAL to ethanoate
  • binds w coenzyme A and enters respitartion
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24
Q

why is it important to orinithine cycle quickly

A
  • ammonia v SOLUBLE nad toxic; bad to let it build up
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25
Q

how is high pressure created in the glomerulus?

A
  • diameter of lumen of AFFERENT arteriole wider than that of EFFERENT
  • pv constant, therefore vol decreases, pressure increases
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26
Q

renal artery leads to …

A

glomerulus (cortex)

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27
Q

renal vein leads to …

A

loop of henle (medulla)

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28
Q

3 layers of ultrafiltraion

A
  1. gaps between endothelial cells, fenestrations
  2. basement membrane (collagen and glycoproteins)
  3. podocytes. major processes, minor processes
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29
Q

how to recognise BC on a microscope pic

A

clear ring of c witohut a stain

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30
Q

basement membrane prevents what

A

anything with an MR of greater than 69000 from leaving

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31
Q

name 5 things filtered out in ultrafiltration

A
  • water
  • glucose
  • amino acids
  • inorganic ions
  • urea
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32
Q

what is left in the capillary after ultrafiltraion

A
  • blood cells
  • proteins
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33
Q

2 functions of kidney

A
  • filter waste from bloood
  • osmoregulation
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34
Q

how to recognise PCT cell vs DCT cell

A
  • PCT brushed border; microvilli
  • PCT smaller lumen
35
Q

what happens in PCT

A
  • selective reabsorption of GLUCOSE and amino acids
36
Q

adaptations of PCT cells

A
  • folded cell membrane to form microvilli ==> more SA for reabsorption
  • CSM contains cotransport proteins
  • many mitochondria to produce lots of ATP
37
Q

mechanism of reabsorption in PCT

A
  1. SODIUM POTASSIUM PUMP: Na+ ACTIVELY pumped OUT of PCT wall, K+ pumped IN.
  2. concentration of Na+ lower inside cells than outside filtrate, creating a CG
  3. Na+ moves down concentration gradient by facilitated diffusion using a COTRANSPORT PROTEIN (with glucose or AA at the same time)
  4. Lowering WP, so water moves in by osmosis
  5. increasing conc of glucose/ aa so it FACILITATED DIFFUSES out through channel protein into the blood
38
Q

need for glucose

A
  • respiratory substrate
  • required for glycolysis
39
Q

mechanism of loop of henle

A

DESCENDING LIMB:
- water permeable
- down the limb, water moves out into capillaries by osmosis thanks to aquaporins (phospholipids are hydrophobic)
- at the same time, na+ and cl- diffuse into LoH
ASCENDING LIMB
- AT THE BASE: mineral ions diffuse out
- as u go up, they move out to medulla by active transport
- no movement of water
- now the wp of medulla is very low, so water continues to move out of descending limb

40
Q

collecting duct (finishing loop of henle)

A
  • fluid passes through tissues with an ever decreasing WP as na+ actively trnasprted out
  • so water moves out by osmosis into capillaries
  • increasing conc of urine
41
Q

describe conc of glucose as it goes along nephron

A
  • high in the PCT
  • sharp decrease back to 0 as glucose is reabsorbed back into the bloodstream
42
Q

describe conc of Na+ as it moves thorugh the nephron

A
  • constant in PCT
  • increase in the loop of henle at first (diffusion into the ascending limb)
  • then decrease (active transport out of ascending limb)
43
Q

describe conc of urea as u move throughout the nephron

A
  • rises gradually throughout as water is withdrawn from the tubule
44
Q

what animals have long loops of henle

A
  • eg camels
  • those living in water deprived aras
  • long loops of henle so max vol water can move out by osmosis into bloodstram
  • smaller volume of more conc. urine
45
Q

describe osmoregulation

A
  • hypothalamus in the brain contains osmoreceptors
  • when WP is low (very negative) osmoreceptor cells lose water by osmosis, become crenated, stimualtes:
  • ADH produced in hyp, then stored in and released from posterior pituitary gland
46
Q

how does ADH work

A
  • WP low, detected by osmoreceptors
  • ADH released by posterior pituitart
  • ADH binds to receptrs in the walls of the collecting duct
  • chain of enzyme controlled reactions
  • vesicles containing aquaporins fuse w CSM, so walls more permeable to water
  • water moves into bloodstream by osmosis
47
Q

example measure of how to assess kidney function

A

GFR
(glomerular filtrate rate)

48
Q

GFR values

A
  • normal: 90-120
  • disease <60
  • failure <15
49
Q

heamodialysis

A
  • filters the blood
  • blood leaves from artery into dialysis machine, flowing through a partilaly permeable dialysis membrane
  • add HEPARIN TO AVOID CLOTTING during dialysis
  • artificial capillaries surrounded by dialysis fluid flowing in the opposite direction (countercurrent mechnaism for a steep cg)
  • blood reenters in a vein
50
Q

kidney translplant

A
  • involves major surgery
51
Q

dialysis +-

A
  • allows u to live
    BUT
  • 2/3 times a week at a clinic for several hours
52
Q

transplant + (3)

A
  • no time consuming dialysis
  • physically fitter
  • better QOL, can travel
53
Q

transplant -

A
  • immunosuppressant drugs
  • major surgery under GA
  • risk of rejection
  • drug side effects
54
Q

3 uses of urine analysis

A
  • preganancy test
  • anabolic steroids
  • glucose for diabetes
55
Q

pregnancy testing

A
  • when ur pregnant, you produce hCG
  • protein smaller than 69000 so can pass from blood into filtrate at BC
    1. urinate on test stick
    2. hCG binds to MOBILE antibodies with a dye, as hormone is COMPLEMENTARY to antibody
    3. they move down test stick
    4. if hCG present: it binds to fixed antibodies holding dye in place, forming a line
    4. mobile antibodies with NO HCG bind to another site to prove test is working
56
Q

how to identify hepatic portal vein

A

blood enters liver through branched vessel

57
Q

adaptations of sinudoid cells (2)

A
  1. flat cells -> short diffusion distance
  2. fenestrated -> increases permeability
58
Q

why can’t podocytes divide by mitosis? (3)

A
  • alraedy differentiated
  • it would alter the number of fenestrations
  • so negatively affect ultrafiltration
59
Q

2 factors affecting GFR

A
  1. age: it declines with age
  2. gender: men and women have different muscle mass
60
Q

purpose of microvilli (2)

A
  • increase SA for resabsorption
  • cotransport proteins for active transport
61
Q

where does ADH act

A

collecting duct

62
Q

descrive effect of a longer loop of henle

A

LONGER DESCENDING:
- more water moves OUT by osmosis, more na+ and cl- move IN by diffusion
LONGER ASCENDING:
- lower volume of water stays constant
- more active transport of na+ and cl- OUT into the medulla
- wp outside nephron decreases, more water reabsorbed in the CD to bloodstream
- smaller vol of more conc urine

63
Q

PCT adaptations (4)

A
  1. microvilli = increased SA for reabsorption
  2. many mitochondria = more ATP , more energy, active transport with sodium potassium pump
  3. lots of ribososmes to produce proteins
  4. carrier/cotransport proteins in the cell membrane
64
Q

what type of vessel is the intralobular vessel in liver

A

vein

65
Q

what tissues line the pCT

A

epithelial

66
Q

what pressure is high in the glomerulus

A

HYDROSTATIC

67
Q

Explain the need for close matching of the donated kidney to the recipient (3)

A
  1. DONATED KIDNEY recognised as foreign
  2. different antigens on the surface of csm
  3. causing rejection and immune response
  4. need to take immunosuppressants
68
Q

lots of creatinine =

A

low GFR = problem

69
Q

where is MOST water reabsorbed into the blood

A

PCT

70
Q

simple role of loop of henle

A

decrease water potential going down medulla

71
Q

why is deamination better than straight excretion of the amino acids

A
  • lose our keto acids
  • can be used in respiration
72
Q

adaptation of kidney cortex?

A
  • dense capillary network to supply nephrons with lots of blood
73
Q

what happens in the pelvis of kidney?

A

urine collects before passing into ureters

74
Q

why might glucose levels decrease a bit despite reabsorption?

A
  • needed to respire
  • to make ATP
  • to release energy fro active processes eg selective reabsorption the sodium potassium pump
75
Q

why does a longer looper henle help those in a drier environment? (3)

A
  • more na+ cl- ions actively transported out of ascending limb into medulla
  • greater WPG in the medulla
  • more water reabsorbed from the CD into the blood
76
Q

how many sides of a lobulbe

A

6

77
Q

what type of cell is hepatocyte

A

epithelial

78
Q

bile duct direction of flow

A

opposite to the HPV nad hepativ artery in the sinudoid

79
Q

bile goes to where

A

gall bladder

80
Q

importance of excreting CO2

A
  1. Co2 + h2o in presence of carbonic anhydrase = carbonic acid. H2CO3 = H+ + HCO3-
  2. H + alter pH, and interact with tertiary structure HB, lowering affinity for oxygen. also form haemoglobinic acid
  3. co2+ Hb = carbaminohaemoglobin, also has a lwoer affinity for oxygen
81
Q

urea compared to ammonia

A
  • less soluble
  • less toxic
82
Q

adaptations of PCT cells

A
  1. highly folded CSM to form microvilli. increases SA for reabsorption
  2. cotransport proteins in CSM
  3. many mitochondria, lots of ATP for active transport
83
Q

name of arrangment in loop of henle

A
  • hairpin countercurrent multiplier system

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