kidney structure and function Flashcards
1
Q
what is the main function of kidneys?
A
regulate blood and fluid
2
Q
what is the waste product excreted by kidneys?
A
urine
3
Q
the ureter, vessels and nerves enter the kidney via what?
A
renal hilum
4
Q
what vessel supplies the kidney with oxygenated blood?
A
renal artery
5
Q
which vessel drains the kidney?
A
renal vein
6
Q
where does the renal artery arise from ?
A
left interior side of abdominal aorta
7
Q
the renal vein connects the kidney to which structure?
A
inferior vena cava
8
Q
which structure transfers urine from the kidney to the bladder?
A
ureter
9
Q
the tube leaving the kidney and entering the bladder is known as what?
A
ureter
10
Q
the kidney id situated behind the peritoneal cavity, what is it described as?
A
retroperitoneal
11
Q
what is the peritoneal cavity?
A
space between the parietal peritoneum and the visceral peritoneum
12
Q
when viewed macroscopically, the kidney consists of 3 distinct parts, what are these?
A
- cortex (outermost part)
- medulla
- pelvis (inner most part)
13
Q
what does the renal cortex contain?
A
85% of all kidney tubules (nephrons)
14
Q
what may a nephron also be referred to as?
A
kidney tubule
15
Q
what is the function of the renal medulla?
A
- site where urine is concentrated
- prevent excess water loss
16
Q
what is the function of the renal pelvis?
A
collection area for which urine is funnelled into the ureter
17
Q
renal arteries deliver blood from which main blood vessel?
A
abdominal aorta
18
Q
name the stages of blood flow from interlobular arteries to interlobular veins
A
- interlobular arteries
- afferent arteriole
- glomerular capillaries’
- efferent arterioles
- peritubular capillaries
- interlobular veins
19
Q
what is unique about the renal vasculature?
A
arterioles > capillaries > arterioles
20
Q
what essentially is the glomerulus?
A
network of cappilaries
21
Q
what is the basic functional unit of the kidney?
A
nephron
22
Q
what is the glomerulus surrounded by?
A
bowman capsule
23
Q
what is the general function of the loop of henle?
A
urine concentration and water resorption
24
Q
which structures of a nephron are found in the renal cortex?
A
- glomerulus
- bowman capsule
- proximal convoluted tubule
- distal convoluted tubule
25
which structures of a nephron are found in the renal medulla?
- loop of henle
| - collecting tubule
26
what is the general function of the distal convoluted tubule?
git rid of excess water
27
name the 2 different types of nephrons?
- cortical nephrons
| - juxtamedullary nephrons
28
which typeof nephron, cortical or juxtamedullary, contains a longer loop of henle?
juxtamedullary
29
the blood filtering component of the kidney is known as what ?
renal corpuscle
30
what structures of a nephron does the renal corpuscle consist of?
- glomerulus
| - bowman capsule
31
which structures of a nephron are involved in reabsorption and secretion?
- proximal convoluted tubule
- loop of henle
- distal convoluted tubule
32
describe the structure of glomerulus?
- single layer endothelial cells surrounded by basement membrane
- fenestrated (pores)
- surrounded by bowman capsule
33
bowman capsule consists of 2 layers, what are these layers?
- parietal (outer layer)
| - visceral (inner layer)
34
the space between the parietal and visceral layers of the bowman capsule is known as what?
bowman space
35
the visceral layer of the bowman capsule is compromised of what specialised epithelium?
podocytes
36
together the glomerulus and bowman capsule are known as what?
renal corpuscle
37
how are the podocytes arranged around the glomerular capillaries?
long branched pedicels of podocytes wrap around the glomerular capillaries
38
what is the renal filtration barrier composed of?
- glomerular endothelium
- basement membrane
- pedicels from filtration barrier
39
the - glomerular endothelium, basement membrane and the pedicels from filtration barrier together form what?
filtration barrier
40
what do the pedicels share a basement membrane with?
fenestrated endothelium
41
what is the renal filtration barrier freely permeable to?
water, glucose, amino acids, sodium, chloride, calcium, phosphate, potassium, bicarbonate, urea, creatine
42
what is the renal filtration barrier not freely permeable to?
large proteins (haemoglobin), cells, negative proteins (albumins)
43
what type of charge does the filtration barrier have?
negative
44
the filtration barrier carries out non-selective filtration based on what ?
charge and size
45
unfiltered blood enters the glomerulus via?
afferent arteriole
46
filtered blood leaves the glomerulus via?
efferent arteriole
47
which glomerular arteriole, afferent or efferent is wider?
afferent
48
how does the afferent arteriole being bigger than the efferent aid filtration from the glomerulus?
increases hydrostatic pressure - force builds up pushing small molecules out
49
the rate at which blood is filtered through the glomerulus into bowman capsule is known as what?
glomerular filtration rate (GFR)
50
what is GFR primarily driven by?
glomerular hydrostatic pressure
51
what is GFR counteracted by?
- hydrostatic pressure in bowman capsule
| - glomerular osmotic pressure
52
what is GFR influenced by?
- hydrostatic pressure
- osmotic pressure
- systemic BP
- renin-angiotensin system
- disease
53
what is the GFR of the average person?
125ml/min or 180l/day
54
what effect does kidney damage have on GFR?
reduces GFR
55
what effect does a reduced GFR have?
- ineffective blood clearance
- ineffective waste removal
- waste products accumulate in blood
56
what substance can be measured in order to asses GFR?
serum creatine levels
57
what do high serum creatine levels indicate about the kidney?
not functioning properly
58
what does the high fenestrations on the glomerular endothelium?
allow rapid transfer of blood plasma
59
molecules are filtered from the blood in the glomerular capillaries to where?
bowman capsule
60
the parietal layer of the bowman capsule contains which type of epithelium?
simple squamous
61
how does the structure of the filtration barrier prevent large molecules passing through?
very small gaps between pedicels
62
what structural component of the filtration barrier prevents the small slits between the pedicels from stretching under pressure and negative molecules passing?
pedicels coated with protein network, protein network is negative which prevents negative molecules passing
63
what do blood proteins in urine indicate?
kidney damage in glomerulus
64
what is the bowman capsule osmotic pressure usually equal to?
0
65
how is glomerular filtration pressure calculated?
glomerular hydrostatic -glomerular osmotic -capsular hydrostatic
66
increased BP has what effect on GFR?
increases GFR
67
where in the nephron is the major site of reabsorption?
proximal convoluted tubule
68
where in the nephron is fine-tuning carried out?
distal convoluted tubule
69
during reabsorption, where does the filtrate pass through?
filtrate in tubule lumen > through epithelial tubule wall > interstitial space > into blooding peritubular capillaries
70
180 litres of filtrate is produced each day however, only 1-2 litres of urine is produced, why is this?
99% of filtrate is reabsorbed
71
what structures make up the renal tubule?
PCV, loop of henle, DCT
72
what is the main function of the renal tubule?
reabsorption (main) and secretion
73
what mechanism does the loop of henle employ?
counter current multiplier
74
the counter current multiplier mechanism reabsorbs what to substances?
sodium and water
75
renal reabsorption refers to the movement of molecules from where to where?
filtrate within renal tubule moving through the tubule wall and interstitial space into the blood in the peritubular capillary
76
renal secretion refers to the movement of molecules from where to where?
molecules in the blood moving through the interstitial space through the tubule wall into the filtrate in the renal tubule
77
is renal secretion active or passive?
active
78
the renal tubule uses sodium handling in a number of ways, what are the functions of this?
- Na transport facilitates reabsorption of nutrients, water and ions
- facilitates secretion of hydrogen ions and water
79
how much of the sodium filtered across the glomerular filtration barrier is reabsorbed in the proximal convoluted tubule?
65%
80
how much of the sodium filtered across the glomerular filtration barrier is reabsorbed in the loop of henle?
25%
81
how much of the sodium filtered across the glomerular filtration barrier is reabsorbed in the distal convoluted tubule?
8%
82
what does the majority of the kidneys energy go towards ?
sodium reabsorption (80%)
83
how much filtrate is reabsorbed in the proximal convoluted tubule?
2/3 of the filtrate
84
how does the long convoluted structure of the PCT aid its function?
increases SA for more reabsorption
85
how does the structure of the convoluted tubule maximise its function?
- long and convoluted to maximise SA
| - microvilli on epithelium to maximise SA
86
the proximal convoluted tubule is closely associated with what capillary ?
peritubular capillary (for absorption into it)
87
filtrate entering the proximal convoluted tubule has a high concentration of what, how does this compare to that of the blood in the peritubular capillaries ?
- ions
- waste products
- nutrients
- blood
blood in peritubular capillaries has low conc of all these
88
is reabsorption of molecules from the tubule lumen into proximal convoluted tubule to blood in the peritubular capillaries active or passive?
passive
89
although reabsorption of molecules from the PCT to blood is passive, it still requires either of 2 things, what are these?
pores or carrier proteins
90
how does water move through the phospholipids bilayer of the PCT?
aquaporin channels
91
what are aquaporin channels ?
free pores that allow the movement of water down its concentration gradient
92
how do glucose and amino acids move through the phospholipids bilayer of the PCT?
they are transported via sodium co transporters on the apical membrane between the tubule lumen and tubule wall
93
where is the apical membrane?
between the tubule lumen and tubule wall
94
glucose and amino acids move from the filtrate into the blood via sodium co transporters, where are these transporters found?
apical membrane
95
what are the 2 types sodium transporters found on the apical membrane the PCT?
- amino acid co transporters
| - glucose co transporters
96
do glucose and amino acids pass through the apical membrane of the PCT actively or passively?
passively
97
how much of the filtrate is reabsorbed passively ?
50%
98
50% of filtrate is reabsorbed by the kidneys passively, what happens to the remaining 50% of the filtrate ?
active sodium reabsorption in PCT
99
where in the kidneys does active sodium reabsorbtion take place?
proximal ct
100
sodium is actively transported across the basolateral membrane of the PCT by which mechanism?
sodium potassium pump
101
where is the basolateral membrane?
between tubule wall and interstitial space
102
sodium portassium pumps use 1 ATP to move how many sodium ions out and how many potassium ions in?
3 sodium out
| 2 potassium in
103
how does the movement of sodium across the basolateral membrane by sodium potassium pumps move other substances?
other things follow sodium:
- water moves by osmosis
- glucose and amino acids are co transported across the apical membrane as Na moves across the basolateral membrane
- negative ions such as Cl follow
104
describe the movement of sodium from the filtrate in the tubule lumen to the epithelium the tubule wall?
sodium ions move from an area of high concentration in the tubule lumen to an area of low concentration in the tubule wall
105
describe the movement of sodium from the tubule wall to the interstitial fluid?
sodium moves across the basolateral membrane actively, from an area of low concentration in the tubular wall to an area of high concentration in the interstitial fluid via sodium potassium pumps
106
describe the movement of sodium from the interstitial space to the blood?
sodium moves passively from a high conc in insterstitial fluid to a low conc in blood
107
where in the sodium reabsorption pathway is sodium found in high concentrations?
- filtrate (tubule lumen)
| - interstitial fluid (interstitial space)
108
the inclusion of the sodium potassium pumps increase sodium reabsorption in the PCT from 50% to what?
65%
109
where does the loop of henle in cortical nephrons extend to?
medulla
110
where does the loop of henle in juxtamedullary nephrons extend to?
deep into the medulla
111
juxtamedullary nephrons are specialised at concentrating urine using what mechanism?
counter current multiplier
112
which type of neuron, cortical or juctamedullar, are most numerous?
cortical
113
the tubule walls of the loop henle can be subdivided into 3 sections, what's are these?
- thin descending limb
- thin ascending limb
- thick ascending limb
114
what happens in the thin descending limb of the loop of henle?
- permeable to water
| - no sodium reabsorption occurs
115
what happens in the thin ascending limb of the loop of henle?
- permeable to water
| - no sodium reabsorption occurs
116
what happens in the thick ascending limb of the loop of henle?
- impermeable to water (no aquaporin channels)
- reabsorbs sodium (25% total filtrate)
- generates osmotic gradient
- facilitate water reabsorption from thin ascending
117
why can water not be reabsorbed in the thick ascending limb of the loop henle?
no aquaporin channels
118
when sodium is actively pumped across the thick ascending limb of the loop of henle, it creates which type of gradient?
osmotic
119
describe the fluid in the interstitial of the loop henle and how creates an osmotic gradient?
- fluid in the interstitium is salty as when sodium moves out of the thick ascending limb water cannot follow
- this salty interstitium draws water out of the thin descending limb osmotically
120
how is sodium drawn into the thick ascending limb in the loop of henle?
- sodium potassium pumps in basolateral membrane
| - NKCC2 transporters on apical membrane
121
how does sodium transportation differ in the PCT and Loop of henle?
- both have sodium potassium pump on basolateral membrane
- PCT uses sodium co transporters on apical membrane
- loop of henle uses NKCC2 transporters on apical membrane
122
which molecules does a NKCC2 pump ?
1 sodium ion, 1 potassium ion, 2 chloride atoms
123
is the NKCC2 (sodium potassium chloride) pump passive or active?
passive
124
what is the target site for diuretic drugs and how do the work?
NKCC2 - prevent sodium and water resorption
125
the ionic concentration of the renal medulla never reaches equilibrium, why is this?
constant pumping action of sodium in ascending limb
126
which structure maintains the concentration gradient in the loop of helm ensuring blood doesn't wash it away?
vasa recta
127
what is the function of the vasa recta?
maintains the concentration gradient in the loop of helm ensuring blood doesn't wash it away
128
describe the rate of blood flow through the vasa recta?
slow and sluggish
129
what is the function of the distal convoluted tubule?
fine-tuning of filtrate by reabsorption of water and salts
130
what effect does dehydration have on water absorption in distal convoluted tubule?
more water resorbed
131
the distal convoluted tubule is the target site for which hormones?
- ADH
- Aldosterone
- ANH
132
what effect does ADH have on the distal convoluted tubule?
increase water reabsorption
133
what effect does Aldosterone have on the distal convoluted tubule?
increase sodium reabsorption
134
what effect does ANH have on the distal convoluted tubule?
promote sodium secretion
135
tubule fluid entering the distal convoluted tubule can be described as what, hypotonic or hypertonic, in relation to the interstitium of the cortex?
hypotonic
136
where is ADH released?
pituitary
137
where is aldosterone released?
adrenal gland
138
where is ANH produced?
smooth muscle in heart atria
139
how does ADH aid water reabsorption?
inserts aquaporin channels into distal convoluted tubule and collecting duct
140
what effect does dehydration have on BP?
decreases
141
how does ANH work?
inhibits ADH and aldosterone therefore inhibiting water and sodium reabsorption
142
which tubule, the PCT or DCT, is longer?
proximal
143
what effect does elevated BP have on volume and concentration of urine produced?
large vol dilute urine produced
144
what effect does reduced BP have on volume and concentration of urine produced?
small vol concentrated urine
145
which structure connects the glomerulus with the distal convoluted tubule?
junta-glomerular apparatus
146
which types of cells does the juxta-glomerular apparatus contain?
- macula densa cells
| - juxtaglomerular cells
147
what is the function of the juxta-glomerular apparatus?
- measure sodium concentration of filtrate (macula densa)
| - adjust diameter of afferent arteriole (juxtaglomerular cell)
148
increased GFR increases sodium filtrate concentration, this is recognised by cells in the macula densa, what effect will this cause juxtaglomerular cells to have?
constrict diameter of afferent arteriole
149
reduced GFR reduces sodium filtrate concentration, this is recognised by cells in the macula densa, what effect will this cause juxtaglomerular cells to have?
increase diameter of afferent arteriole
150
what do juxtaglomerular cells secrete when BP falls?
renin
151
renin is secreted by juxtaglomerular cells when BP fall, how does this help to increase BP?
- renin activates the renin-angiotensin system which produces angiotensin ii
- angiotensin ii is a potent vasoconstrictor
152
describe the steps in the renin-angiotensin system?
- angiotensin released into circulation
- renin converts angiotensin into angiotensin i
- angiotensin converting enzyme converts angiotensin i into angiotensin ii
153
which 2 structures detect angiotensin ii, and what do they release in response to it?
- adrenal medulla (aldosterone)
| - hypothalamus (ADH)
154
which hormone counteracts the renin-angiotensin system?
ANH
155
which change in BP results in the release of ANH?
increased BP
156
which type of feedback maintains GFR?
tubuglomerular feedback
157
which two chemicals do macula densa cells produce in order to signal to juxtaglomerular cells?
- adenosine
| - prostaglandins
158
adenosine is released by macula densa cells in response to what?
high sodium/high GFR
159
prostaglandins is released by macula densa cells in response to what?
low sodium/low GFR
160
juxtaglomerular cells vasoconstrictor in response to what chemical?
adenosine
161
juxtaglomerular cells vasodilator in response to what chemical?
prostaglandins
162
prostaglandin stimulates juxtaglomerular cells to release what?
renin
163
what effect does the renin-angiotensin system have on blood pressure?
raises BP
164
renin-angiotensin system raises BP via which molecule?
angiotensin ii
165
renin-angiotensin system raises blood volume via which 2 hormones?
- aldosterone
| - ADH
166
list some storms of chronic kidney disease
- oedema (ankles, hands, feet, lungs)
- nausea
- anaemia
- weak/painful bones
167
list some causes of chronic kidney disease
- hypertension
- diabetes
- kidney infection
- high cholesterol
- glomerulonephritis
- polycystic kidney disease
- kidney stones
168
chronic kidney disease is closely associated with which other disease?
CVD
169
which types of drugs may be used to regulate hypertension?
- diuretics
- ACE inhibitors (captopril)
- Beta blockers
- furosemide
170
how do diuretics work to lower BP and regulate hypertension?
break the cycle of high bp caused by increases renin
171
how do ACE inhibitors work to lower BP and regulate hypertension?
inhibit angiotensin ii
172
how do beta blockers work to lower BP and regulate hypertension?
block sympathetic nerve stimulation by stress hormones
173
how does furosemide work to lower BP and regulate hypertension?
block NKCC2
174
what effect does reduced kidney function have on drug metabolism and what alteration must you make when prescribing a drug to someone suffering from reduced kidney function?
patients can't remove the drug effectively so smaller dose is prescribed
175
which stage of kidneys disease is the end stage of renal disease, resulting in less than 15% of kidney function?
stage 5
176
what is dialysis?
artificial removal of waste, solutes, water and toxins from blood
177
what are the two types of kidney dialysis?
- haemodialysis
| - peritoneal dialysis
178
which type of kidney dialysis can be carries out at home?
peritonial dialysis
179
what are the 2 treatment options for stage 5 kidney disease?
- dialysis
| - kidney transplant
