5.1.2 excretion as an example of homeostatic control Flashcards
(92 cards)
1
Q
excretion defintion
A
-removal of metabolic waste PRODUCTS
- from the body
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
3
Q
3 main metabolic waste products
A
co2
bile pigments
urea
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
5
Q
role of skin in excretion
A
sweat contains urea, salts, uric acid, water, ammonoia
6
Q
name of 3 blood vessels in liver
A
- hepatic vein
- hepatic portal vein
- hepatic artery
7
Q
hepatic vein
A
- takes the DEOXYGENATED blood from the liver, joins the vena cava and back to lungs to be oxygenated
- in diagram: big on on the other side
8
Q
how to idnetify hepatic vein in histology
A
LARGEST LUMEN
9
Q
hepatic artery
A
- oxygenated blood goes from heart to aorta to liver via here
10
Q
hepatic portal vein
A
- DEOXYGENATED blood from the digestive system carrying digestive (someties toxic) products
11
Q
need for oxygen
A
- aerobic respiratoin
- last electron accepter in ox phos
12
Q
bile duct
A
carries bile from liver to gall bladder
- above HPV on diagram
13
Q
interlobular vessel is …
A
branch of hepatic vein (central vein)
14
Q
sinusoid
A
blood capillary connecting the ha and hpv to hepativ vein
15
Q
features of hepatocytes
A
-MULTIPOTENT, so liver can repair itself
- microvilli
- large nucleis
- lots of golgi
- lots of mitochonrdira
16
Q
KUPFFER CELLS
A
- macrophages that move within sinusoids
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
18
Q
production of bile
A
- bile released into bile CANNALICULUS
- goes to BILE DUCT
- transports bile to gall bladder
19
Q
purpose of bile
A
EMULSIFICATION and NEUTRALISATION of digested material entering small intestine
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
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
urea then excreted in the kidneys
22
Q
role of liver: hydrogen peroxide
A
- catalase enzyme breaks it down into water and oxygen
- as it is toxic
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
24
Q
why is it important to orinithine cycle quickly
A
- ammonia v SOLUBLE nad toxic; bad to let it build up
25
how is high pressure created in the glomerulus?
- diameter of lumen of AFFERENT arteriole wider than that of EFFERENT
- pv constant, therefore vol decreases, pressure increases
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renal artery leads to ...
glomerulus (cortex)
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renal vein leads to ...
loop of henle (medulla)
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3 layers of ultrafiltraion
1. gaps between endothelial cells, fenestrations
2. basement membrane (collagen and glycoproteins)
3. podocytes. major processes, minor processes
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how to recognise BC on a microscope pic
clear ring of c witohut a stain
30
basement membrane prevents what
anything with an MR of greater than 69000 from leaving
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name 5 things filtered out in ultrafiltration
- water
- glucose
- amino acids
- inorganic ions
- urea
32
what is left in the capillary after ultrafiltraion
- blood cells
- proteins
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2 functions of kidney
- filter waste from bloood
- osmoregulation
34
how to recognise PCT cell vs DCT cell
- PCT brushed border; microvilli
- PCT smaller lumen
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what happens in PCT
- selective reabsorption of GLUCOSE and amino acids
36
adaptations of PCT cells
- folded cell membrane to form microvilli ==> more SA for reabsorption
- CSM contains cotransport proteins
- many mitochondria to produce lots of ATP
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mechanism of reabsorption in PCT
1. SODIUM POTASSIUM PUMP: Na+ ACTIVELY pumped OUT of PCT [into blood] 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 FROM THE FILTRATE(with glucose or AA at the same time)
4. Lowering WP, so water moves in by osmosis FROM BLOOD
5. increasing conc of glucose/ aa so it FACILITATED DIFFUSES out through channel protein into the blood
6. and k+ FD out into the filtrate
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need for glucose
- respiratory substrate
- required for glycolysis
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mechanism of loop of henle
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 as IMPERMEABLE
- now the wp of medulla is very low, so water continues to move out of descending limb
40
collecting duct (finishing loop of henle)
- 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
describe conc of glucose as it goes along nephron
- high in the PCT
- sharp decrease back to 0 as glucose is reabsorbed back into the bloodstream
42
describe conc of Na+ as it moves thorugh the nephron
- 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
describe conc of urea as u move throughout the nephron
- rises gradually throughout as water is withdrawn from the tubule
44
what animals have long loops of henle
- 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
describe osmoregulation
- 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
how does ADH work
- WP low, detected by osmoreceptors in hypothalamus
- ADH released by posterior pituitar, travels in blood
- ADH binds to receptrs in the walls of the collecting duct
- activates g proteins, adenyl cyclase, camp
- chain of enzyme controlled reactions
- vesicles containing aquaporins fuse w CSM, so walls more permeable to water
- water moves into bloodstream by osmosis
- small vol of more concentrated urine
47
example measure of how to assess kidney function
GFR
(glomerular filtrate rate)
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GFR values
- normal: 90-120
- disease <60
- failure <15
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heamodialysis
- 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
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kidney translplant
- involves major surgery
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dialysis +-
- allows u to live
BUT
- 2/3 times a week at a clinic for several hours
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transplant + (3)
- no time consuming dialysis
- physically fitter
- better QOL, can travel
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transplant -
- immunosuppressant drugs
- major surgery under GA
- risk of rejection
- drug side effects
54
3 uses of urine analysis
- preganancy test
- anabolic steroids
- glucose for diabetes
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pregnancy testing
- 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
how to identify hepatic portal vein
blood enters liver through branched vessel
57
adaptations of sinudoid cells (2)
1. flat cells -> short diffusion distance
2. fenestrated -> increases permeability
58
why can't podocytes divide by mitosis? (3)
- alraedy differentiated
- it would alter the number of fenestrations
- so negatively affect ultrafiltration
59
2 factors affecting GFR
1. age: it declines with age
2. gender: men and women have different muscle mass
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purpose of microvilli (2)
- increase SA for resabsorption
- cotransport proteins for active transport
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where does ADH act
collecting duct
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descrive effect of a longer loop of henle
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, steeper concentration gradient, more water reabsorbed in the CD to bloodstream
- smaller vol of more conc urine
63
PCT adaptations (4)
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
what type of vessel is the intralobular vessel in liver
vein
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what tissues line the pCT
epithelial
66
what pressure is high in the glomerulus
HYDROSTATIC
67
Explain the need for close matching of the donated kidney to the recipient (3)
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
lots of creatinine =
low GFR = problem
69
where is MOST water reabsorbed into the blood
PCT
70
simple role of loop of henle
decrease water potential going down medulla
71
why is deamination better than straight excretion of the amino acids
- lose our keto acids
- can be used in respiration
72
adaptation of kidney cortex?
- dense capillary network to supply nephrons with lots of blood
73
what happens in the pelvis of kidney?
urine collects before passing into ureters
74
why might glucose levels decrease a bit despite reabsorption?
- needed to respire
- to make ATP
- to release energy fro active processes eg selective reabsorption the sodium potassium pump
75
why does a longer looper henle help those in a drier environment? (3)
- 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
how many sides of a lobulbe
6
77
what type of cell is hepatocyte
epithelial
78
bile duct direction of flow
opposite to the HPV nad hepativ artery in the sinudoid
79
bile goes to where
gall bladder
80
importance of excreting CO2
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
urea compared to ammonia
- less soluble
- less toxic
82
adaptations of PCT cells
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
name of arrangment in loop of henle
- hairpin countercurrent multiplier system
84
blood supply TO kidneys
in the renal artery
85
blood supply away from kidneys
renal vein
86
how to tell diff between renal artery and renal vein
renal vein has 2 branches to kidney
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which parts of nephron are in th emedulla
only
collecting duct
loop of henle
88
how to histology identify bowman's capsule
- region WITHOUT staining
89
what are the capillary cells in the glomerulus
squamous endothelial
90
DCT
- larger lumen + no microvilli
- Selective Reabsorption OF MINERAL IONS
91
if electrolyte level in your blood is high that indicates a problem with
- DCT
- selective reabsorption
- glomerulus
- ultrafiltration
92
adaptations of sinusoid walls
- thin endothelium cells so short diffusion distance
- fenestrated, to increase permeability
