Renal anatomy and physiology and renal blood flow Flashcards
1
Q
Where are the kidneys located?
A
The kidneys lay in the retro peritoneal space of the abdominal cavity, one on each side of the spine.
2
Q
The kidneys have 7 functions which include:
A
- excretion of metabolic waste products
- maintenance of water balance
- regulation of acid base balance
- blood pressure regulation
- secretion of erythropoietin
- activates vitamin D
- glucose regulation
3
Q
The secretion of erythropoietin by the kidneys has what effect?
A
stimulates the growth of red blood cells
4
Q
Disorders which affect the kidney can cause anemia due to?
A
a decrease in the production of erythropoietin resulting in anemia
5
Q
What is the active form of vitamin D?
A
calcitriol
6
Q
The kidneys activate which vitamin?
A
vitamin d - into calcitriol
7
Q
Calcitriol has what function?
A
assists with the absorption of calcium in the intestines
8
Q
Vitamin D steps to absorption (5)
A
- ingested in the food we eat (veg & meat)
- after absorption it is taken to the skin
- UV light changes it to a precursor of vit D
- transported to the kidneys
- converted into the active form of vit D - calcitriol
9
Q
Calcitriol is reponsible for:
A
- assisting with the absorption of calcium in the intestines
- promoting the release of calcium from the bone (re-absorption)
- decreasing renal calcium excretion
10
Q
The kidneys help maintain glucose balance by:
A
- completing gluconeogenesis from amino acids
- uptake of glucose from the circulation
- reabsorbing glucose from glomerular filtrate
11
Q
The kidneys normally filter how much glucose per day by the glomeruli filter?
A
180 grams
12
Q
After glucose is filtered by the kidneys, where is it absorbed?
A
in the proximal tubule
13
Q
What absorbs the glucose in the proximal tubule?
A
the sodium-glucose co-transporter 2 (SGLT2) protein
14
Q
Why does the sodium-glucose transporter 2 (SGLT2) protein absorb all the glucose in the proximal tubule?
A
this helps to ensure adequate glucose is available during periods of fasting
15
Q
What happens when the serum glucose exceeds a threshold of 180?
A
the SGLT2 transporters become saturated and the excess glucose spills over into the urine
16
Q
What is a diabetes drug class protein inhibitor?
A
SGLT2 inhibitors
17
Q
What do SGLT2 inhibitors medications do?
A
This drug class inhibits this protein and allows for glucose to spill over into the urine thus decreasing serum glucose levels.
18
Q
What is the outer most portion of the kidney and is made of fibrous tissue?
A
renal capsule
19
Q
What is the fatty layer of tissue that adheres each kidney to the posterior wall of the abdomen?
A
renal fascia
20
Q
What is directly below the renal capsule and extends between the medullary pyramids?
A
renal cortex
21
Q
What houses the renal corpuscles and the proximal and distal tubules of the nephron?
A
renal cortex
22
Q
What is pyramid-shaped in the kidney?
A
renal medulla
23
Q
What is the inner darker portion of the kidney tissue consisting of renal pyramids?
A
renal medulla
24
Q
What contains the secreting and collecting tubules?
A
renal pyramids
25
What extend from the medulla?
renal calyces
26
The renal calyces merge together to form?
the renal pelvis
27
What gives rise to the ureter which extends to the bladder?
renal pelvis
28
What is the functional unit of the kidney?
nephron
29
What are the two types of nephrons?
cortical nephron and juxtamedullary nephron
30
Where is the cortical nephron?
renal cortex
31
Where is the juxtamedullary nephron?
lays close to and extends into the medulla
32
What are the three main functional parts of the nephron?
glomerulus, bowman's capsule, tubular system
33
What is a collection of capillaries which receives blood from the renal artery?
glomerulus
34
What is the function of the glomerulus?
It is responsible for filtering the blood
35
What partially encases the glomerulus and extends to form the tubule system?
bowman's capsule
36
Together the glomerulus and bowman's capsule are termed?
renal corpuscle
37
A collection of tubules which originate from the bowman's capsule
the tubule system
38
The proximal tubule comes directly off the?
bowman's capsule
39
What is the recipient of the filtrate?
the proximal tubule
40
The filtrate flows from the glomerulus into the bowman's capsule and then into?
the proximal tubule
41
What reabsorbs all the glucose?
the proximal tubule
42
The proximal tubule reabsorbs glucose and?
amino acids, HCO3, Na, Cl, phosphate, potassium, and water
43
A serum glucose above 180 mg/dL will exceed the renal threshold for glucose and result in?
glucosuria
44
What causes damage associated with diabetes mellitus?
glucosuria
45
What is stimulated by the parathyroid hormone will excrete phosphate?
the proximal tubule
46
What is the site of action for angiotensin II which stimulates Na, water, and bicarbonate reabsorption?
the proximal tubule
47
What extends from the proximal tubule?
the descending loop of Henle
48
What is impermeable to Na, passively reabsorbs water, and concentrates urine?
the descending loop of Henle
49
What extends from the descending loop of Henle?
the ascending loop of Henle
50
What actively reabsorbs sodium, potassium, and chloride?
the ascending loop of Henle
51
What induces the reabsorption of magnesium, calcium, and it is impermeable to water (making the urine more dilute)?
the ascending loop of Henle
52
What extends from the ascending loop of Henle?
the distal convoluted tubule
53
What actively reabsorbs sodium, is impermeable to water, and causes urine to be more dilute?
the distal convoluted tubule
54
Where does the parathyroid hormone increase calcium reabsorption?
the distal convoluted tubule
55
What extends from the distal convoluted tubule?
the collecting tubule
56
What connects with the renal pyramids?
the collecting tubule
57
What reabsorbs sodium in exchange for potassium and hydrogen?
the collecting tubule
58
What hormone regulates the process in the collecting tubule of sodium reabsorption in exchange for potassium and hydrogen?
aldosterone
59
Where is the site of action for anti-diuretic hormone?
the collecting tubule
60
What are epithelial cells in the bowman's capsule which wrap around the capillaries of the glomeruli?
podocytes
61
Podocytes form long processes (foot projections) called?
pedicels
62
What wraps around the glomerular capillaries and leave slits between them?
pedicels formed by podocytes
63
What is filtered between the slits (pedicels)?
blood
64
What is located in the area just proximal to the renal corpuscle, between the afferent and efferent arterioles, and where the distal tubule loops up and makes contact with the afferent arteriole?
the juxtaglomerular apparatus (JGA)
65
The JGA is a collection of cells consisting of?
juxtaglomerular cells, the macula densa, and the mesangial cells
66
Where are the juxtaglomerular cells located?
in the wall of the afferent arterioles
67
What is the function of the juxtaglomerular cells?
they monitor renal pressure and help to maintain normal GFR through the release of renin
68
What happens when renal perfusion is decreased?
the juxtaglomerular cells are responsible for releasing renin to help increase GFR
69
The end result of renin?
the release of angiotensin II which constricts the efferent arteriole thereby increasing pressure to the glomerulus
70
A group of epithelial cells located in the distal convoluted tubule that are in close contact with afferent and efferent arterioles. They help regulate GFR.
macula densa
71
Located in the section between the afferent and efferent arterioles and among the glomerular capillaries.
mesangial cells
72
Function as macrophages and are able to contract to regulate blood flow of the glomerular capillaries
mesangial cells
73
The kidneys receive approximately how much blood per minute which is a sizable portion of the cardiac output?
1000-1200mL
74
As the blood enters the ____, ____% of this plasma is filtered out of the capillaries and enters the ____?
glomerulus
20%
bowman's capsule
75
the filtrate then enters the _____ at a rate of approximately ____mL per minute. This is known as the _____.
proximal tubule
125mL
glomerular filtration rate (GFR)
76
The remaining ____% of plasma is not filtered into the bowman's capsule but instead flows out of the glomerular space and into the ______.
80%
| efferent arterioles
77
the efferent arterioles then divide into millions of capillaries that surround the tubules and are called
peritubular capillaries
78
the network of capillaries in conjunction with epithelial cells of the tubules is responsible for
solute exchange and water regulation
79
___ branch off the abdominal aorta, go into the kidneys and become the _____ of the glomerulus and form the ______
renal arteries
afferent arteriole
glomerular arterioles
80
Renal blood flow....
```
abdominal aorta
renal arteries
into the kidneys
afferent arterioles of
glomerulus
glomerular arterioles
efferent arteriole
peritubular capillaries
connect with the venous
system
inferior vena cava
```
81
In normal physiology what assist with the dilation of the afferent arterioles
prostaglandins
82
The dilation of the afferent arterioles results in increased blood flow to the glomeruli and ___
increase GFR
83
Some prostaglandins produced by the arachidonic pathway are
renal protective
84
NSAIDS block the production of renal protective prostaglandins and can cause __
AKI
sodium retention
and edema
85
Angiotensin II constricts mainly?
the efferent arterioles in the glomeruli
86
Angiotensin II causes?
increase in GFR and glomerular pressure
87
ACE inhibitors block the action of
angiotensin II
88
ACE inhibitors block the action of angiotensin II on the ___
efferent arterioles
89
ACE inhibitors block the action of angiotensin II on the efferent arterioles and therefore
have a renal protective quality in diabetics because it decreases the pressure within the glomeruli - but this could also result in AKI particularly in someone with renal artery stenosis
90
Renal blood flow is regulated by
a variety of auto regulatory processes
91
The regulatory systems affect
the amount of blood which flows to the kidneys and also the rate of filtration
92
What is EABV?
effective arterial blood volume
93
A decrease in the arterial blood pressure or a decrease in the EABV causes?
a decrease in renal perfusion
94
A decrease in renal perfusion causes
the filling pressure of the glomerular arterioles to decrease which in turn decreases the GFR
95
A decrease in GFR leads to
a decrease in the fluid and sodium in the distal tubule
96
A decrease in the fluid and sodium in the distal tubule is sensed by the JGA which then does 2 things?
1 - it sends signals to the afferent arterioles to relax which increases the flow of blood to the glomeruli
2 - the JGA releases more renin
97
What does renin do related to the kidneys?
1 - converts the plasma protein angiotensinogen to angiotensin I
2 - angiotensin I passes through the lungs and stimulates the release of (ACE) angiotensin converting enzyme
3 - ACE then converts angiotensin I to angiotensin II
4 - which stimulates vasoconstriction of efferent arterioles
5 - this helps increase glomerular back pressure
6 - this increases GFR
98
What does angiotensin II responsible for besides vasoconstriction?
it is also responsible for stimulating the release of aldosterone.
99
What does aldosterone do related to the kidneys?
is the hormone of sodium regulation and signals to the collecting ducts in the nephron to reabsorb Na. The increase in sodium load leads to an increase in water retention and ultimately an increase in blood volume, blood pressure, and GFR.
