Renal Anatomy Flashcards
1
Q
What is the FUNCTION of the ureters?
A
Transportation of urine from the kidneys to the bladder
2
Q
What is the length of the ureters?
A
The ureters are muscular tubes that are 25 - 30 cm long
3
Q
What is the FUNCTIONS of the urinary bladder?
A
Functions as a temporary storage of urine
4
Q
What is the urinary bladder composed of?
A
The urinary bladder is composed of:
Smooth Muscle
(DETRUSOR MUSCLE)
5
Q
What is the function of the Detrusor muscle of the bladder?
A
The Detrusor muscle of the bladder functions by CONTRACTION to ultimately empty the bladder
6
Q
Describe the urinary bladder.
A
The urinary bladder is HOLLOW, VISCUS, & VERY DISTENSIBLE
7
Q
What are the THREE parts of the urinary bladder?
A
Two Parts of the Urinary Bladder:
BODY
Bladder TRIGONE - triangular region, DIRECTLY above the neck
NECK - funnel shape connection that connects to the urethra
8
Q
What is the function of the Urethra?
A
The urethra functions to transport urine from the bladder our of the body
9
Q
What is the length of the male urethra? Female?
A
Male
18 - 20 cm long
Female
4 cm long
10
Q
Where is the location of the kidneys?
A
The kidneys lie RETRO-PERITONEALLY (external to the peritoneal cavity) in the SUPERIOR LUMBAR REGION
11
Q
What are the two surfaces of the kidneys?
A
Lateral Surface
Convex
Medial Surface
Concave
12
Q
What is the Renal Hilum? Location? Function?
A
THE RENAL HILUM
Location
On the medial side of the kidney
Function
It is where the Ureters, Blood vessels, Lymphatics, and Nerves EXIT
13
Q
What is the function of the
Fibrous Capsule
Adipose Capsule
Renal Fascia
A
Fibrous Capsule
Surround the kidney and PROTECTS it from renal infection
Adipose Capsule
The fat surrounding the kidney and CUSHIONS the kidney and helps attach it to the body wall
Renal Fascia
Outer layer of DENSE CONNECTIVE TISSUE that helps to ANCHOR the kidney
14
Q
How much does the adult kidney weigh?
A
Adult kidney weighs 150 g
15
Q
What are the THREE major areas of the kidneys?
A
Renal Cortex
Renal Medulla
Renal Pelvis
16
Q
Where is the CORTEX of the kidney located?
A
The Cortex is the light colored, GRANULAR, SUPERFICIAL (outer) region
17
Q
What structures are located in the CORTEX?
A
Renal Corpuscles
Proximal Renal Tubules
Distal Renal Tubules
18
Q
What are the renal columns?
A
The Renal Columns are extensions of the Renal Cortex
They extend douwn between the Renal Mudulla Pyramids
They contain Urinary Tubules and Blood Vessels
19
Q
Where is the MEDULLA of the kindey located? Composition?
A
Medulla (inner layer)
Exhibits 8 - 10 cone-shaped medullary (renal) pyramids separated by Renal Columns
**The medullary pyramid and its surrounding capsule constitutes a LOBE
The renal medulla is further divided into cone shaped Renal Pyramids
20
Q
The Medullary Pyramids are further divided into what structures?
A
The Medullary Pyramids are further divided into RENAL PYRAMIDS
- Base of Pyramid: located at the border, where the Renal Cortex and the Renal Medulla meet
- Apex of Pyramid:“Renal Papilla” projects into the Renal Pelvis
21
Q
What structures are located in the Renal Medulla?
A
ASCENDING & DESCENDING Limbs of the Loop of Henle
Collecting Ducts
22
Q
What is the Renal Sinus?
A
The Renal Sinus is a cavity within the kidney which is occupied by the Renal Pelvis, Major and Minor calyces, blood vessels, nerves and fat.
23
Q
What is the Renal Pelvis? What structures form it?
A
The Renal Pelvis is a flat funnel shaped tube lateral to the hilus within the renal sinus
It is a Continuation (extension) of the proximal ureter
Composed from:
Major and Minor Calyces
They Collect the urine from the tubules of the papilla
24
Q
How much of Cardiac Output is Renal Blood Flow?
A
Renbal Blood Flow is 22% of Cardiac Output
(1,100 ml/min)
25
Describe the steps (Flow) of Renal Blood Flow
Renal Artery
Interlobar Arteries
Arcurate Arteries
Interlobular (Renal) Arteries
Afferent Arterioles
Glomerulus
Efferent Arterioles
**\*Peritubular Capillaries**
Interlobular Veins
Arcurate Veins
Interlobular Veins
Renal Vein
26
What are the TWO capillary beds of the Renal Blood supply?
1. **GLOMERULAR Capillary Bed**
Afferent arteriole - Capillary bed - Efferent arteriole
2. **PERITUBULAR Capillary Bed**
"Come off of" the efferent arterioles and suround the renal tubules
27
What is the function of the GLOMERULAR capillary bed?
**_FILTRATION_**
Filtration of blood entering through the Afferent arteriole
28
What is the HYDROSTATIC PRESSURE within the glomerular capillary bed?
**_60 mmHg_**
## Footnote
The HIGH hydrostatic pressure is what is effectively pushing fluid out/causing filtration of fluid from capillaries in the glomerulus into bowman's capsule tubules to become urine.
29
What is the COLLOID OSMOTIC PRESSURE within the glomerular capillary bed?
**_34 mmHg_**
## Footnote
The Colloid Osmotic pressure is what is the PULLING pressure of protiens within the glomeular capillaries
\*Bowman's capsule has ZERO proteins, thus its Colloid Osmotic pressue is 0 mmHg
30
What is the function of the PERITUBULAR capillary bed?
**REABSORPTION**
HYDROSTATIC PRESSURE in the peritubular capillary bed is significantly lower (**_13 mmHg_**), so favors fluid going from the tubules back into peritubular capillaries
Venous side: peritubular capillaries empty into venous system that runs parallel to arteriole system into interlobar vein etc until it gets to renal vein
31
What is the FUNCTIONAL unit of the kidney?
**The NEPHRON**
32
What does the Nephron consists of?
**Glomerulous**
+
**Renal Tubules**
33
How many Nephrons does one kidney consists of?
**1 Million**
\*You CANNOT make more
34
What percentage of nephrons does one lose after the age of 40?
We lose **_10%/ decade_** after the age of 40
35
Where is the glomerulous located?
The Glomerulous is located within the **BOWMAN'S CAPSULE**
36
Name the different renal tubules locared within the kidney.
**Proximal Convoluted Tubule** (PCT)
**Loop of Henle** (LOH)
**Distal Convoluted Tubule** (DCT)
**Collecting Duct**
37
What is contained within the DCT?
**The JUXTAGLOMERULAR APPARATUS**
which constains the **MACULA DENSA.** It is involved in **autoregulation** & control of RBF
38
What are the two types of Nephrons?
**Cortical Nephrons**
**+**
**Juxtamedullary Nephrons**
\*\*All nephrons have same parts, but differences based on:
Their **LOCATION** within the kidney
+
The **LENGTH of their LOH**
39
Describe the Cortical Nephrons.
Originates in the **OUTER 2/3 OF THE CORTEX**
Significantly **SHORTER** **LOH** and only goes part way into the medulla
\*Contains pertubualr capillaries that run parallel to the tubules
40
Describe the Juxtamedullary Nephrons.
Its renal corpuscle Originates in the **INNER 1/3 OF THE CORTEX** (the deepest part of the cortex), closest to the junction with the medulla
LOH are **LONGER** and go deep into the medulla of kidney
**Comprises 20 - 30% of nephrons**
Because the LOH runs deeper into the medulla, uxtamedullary Nephrons are **responsible for creating an osmotic gradient within the medulla**
41
How is the blood supply of the Juxtamedullary Nephrons different from the Cortical Nephrons?
The Juxtamedullary Nephrons have **VERY LONG EFFERENT ARTERIALS**.
The Efferent arterial runs deep into the medulla and they become **A VERY SPECIALIZED peritubular capilary network:**
the **VASA-RECTA**
The capillaries in the Vasa-Recta in the lie side by side with the LOH
Its specifically this anatomic relationship of the Vasa-Recta lying side by side w/ the long LOH that creates **CONCENTRATED URINE**
42
What are the three layers of the glomerulous capillaries?
**_Endothemium_**
Usually just a single cell layer
\*Perforated with **fenestrations** (holes) - like swiss cheese
These fenestrations make it freely permeable to everything **_except for RBC/ WBC/ Platelets and plasma proteins_**
Plasma proteins don't pass b/c too large, and also b/c there is a negative charge on the cells and negative charge on the plasma proteins - prevents it from passing
**_Basement Membrane_**
**Gel-like mesh with large spaces**, through which large amount of water and small solutes can pass. Like a kitchen sponge.
No **_RBC/ WBC/ Platelets and plasma proteins_** can pass, partly b/c of size and partly b/c of negative charge
**_Epithelium (PODOCYTES)_**
Rests on the basement membrane and surrounds the outer surface of glomerular capillaries
**They are not continuous**
Foot-like projections = **podocytes**
43
What is the functional significance of 3 layers to the glomerulous capilaries?
Functional significance of the arrangement is that it **permits large volumes of fluid from capillaries into bowman’s capsule, but still restricts RBC/ WBC/ Platelets/ Albumin and plasma proteins**
Most capillaries only have 2 layers including endothelium and basement membrane
44
What are Mesangial Cells? Function? Location?
**_Located_** between the basement membrane + endothelium
**_Functions_** as **PHAGOCYTES**- can remove trapped material
_Also contain myofilaments so can contract_ in response to stimuli just like vascular smooth muscle cells
\*Between and within the loops of glomerular capillaries, but not a layer in and of themselves
45
What is an important feature of Mesangial Cells?
They contain **MYOFILAMENTS,** **so they can contract in response to stimuli** just like vascular smooth muscle cells
When they contract, will **DECREASE FILTRATION** b/c **DECREASE SURFACE AREA** available for filtration
Mesangial cells contract = area for filtration will decrease
46
What substances causes contraction Mesangial Cells? Which substances causes relaxation?
**_Causes Contraction:_**
Angiotensin II
Vasopressin
NE
Histamine
**_Causes Relaxation:_**
Dopamine
47
What are the function(s) of the kidneys?
1. **Excretion of metabolic waste products**
2. **Regulation of:**
Water & Electrolytes
Osmolarity
Acid-base balance
Blood Pressure - RAAS
3. **Secretion, metabolism, & excretion of hormones erythropoietin to stimulate RBC production**
4. **Gluconeogenesis**
5. **Activation of Vitamin D**
48
What are the THREE broad processes that take place in the kidney?
1. **Glomerular Filtration**
2. **Tubular Reabsorption**
3. **Tubular Secretion**
49
Describe the process of Glomerular Filtration.
**_Glomerular Filtration_**
Moving from the curculation (Blood) → Tubular Fluid (Urine)
Filters the blood as goes through glomerular capillaries, so that b/c of those three layers - fluid & solutes (but not cells or plasma proteins) go from blood into effectively urine (but not final product yet)
b/c just about everything except proteins and cells will go into glomerular filtrate, the concentration of those
substances (electrolytes, etc) will be the same as it is in the plasma as glomerular filtrate
but most patients aren't spilling protein in urine, so minimal amount of protein in urine is often from shed epithelial cells, not from albumin or protein in plasma
shouldn't have protein or cells in urine
50
Describe the process of Tubular Reabsorption.
**_Tubular Reabsorption_**
Tubular Fluid (Urine) → Peritubular Capillaries (Blood)
Composition changes based on what the body needs
More important quantitatively
Whatever substance is goes from tubular fluid/urine back into the blood
51
Describe the process of Tubular Secretion.
**_Tubular Secretion_**
Peritubular Capillaries (Blood) → Tubular Fluid (Urine Secretion)
Composition changes based on what the body needs
Something going from blood lower down in tubule from peritubular capillaries into the urine
**Two substances that get secreted from blood into renal tubules to get excreted**
1. Hydrogen ions
2. Potassium ions
52
Between Reabsorption vs Secretion, which is more important?
Quantitatively **REABSORPTION** is more important!
53
What is the major goal of glomerular filtration?
Goal of glomerular filtration is to eliminate the waste products but by reabsorption to retain water and electrolytes!
54
Urine formation is determined by by what processes?
1. **Glomerular Filtration**
2. **Tubular Reabsorption**
3. **Tubular Secretion**
55
What is filtered INTO the tubular fluid?
**Waste products of metabolism:**
_Urea_ – from the breakdown of amino acids
_Creatinine_ – from the breakdown muscle creatine
_Uric acid_ – from the breakdown nucleic acids
_Bilirubin_ – from the breakdown of hemoglobin
**Hormone Metabolites**
**Electrolytes** (mostly reabsorbed)
**Amino Acids** (mostly reabsorbed)
**Glucose** – (mostly reabsorbed) - glucose is reabsorbed only when Blood Glucose levels are **_BELOW_** the **“renal threshold” (160 - 190 ml/ dL)**, above this, glucose spills into the urine
**\*\*The concentration of these products are the same as in plasma**
56
How much is filtered? (What is Glomerular Filtration Rate?)
_Glomerular Filtration Rate (GFR):_
**125 ml/ min**
**180 ml/ day**
Correlates w/ the surface area for filtration (# of nephrons)
**GFR ~10% less in women**
57
What determines GFR?
GFR is determined by:
1. **_Starling Forces:_**
Hydrostatic Pressure
+ Colloid PRessure
2. **Capillary Filtration Coefficient (Kf)**
3. **Filtration Fraction**
58
What are Starling Forces?
1. **_Hydrostatic Pressure_** - Pushing Pressure
**60 mmHg in glomerular capillaries** pushing fluid from glomerulus into bowman's capsule
**18 mmHg in bowman's capsule** opposing filtration - pushing fluid from bowman's capsule into glomerulus
**60 mmHg - 18 mmHg** **= 42 mmHg**
2. **_Colloid Osmotic Pressure_** - Pulling Pressure
**32 mmHg - plasma proteins in glomerular capillaries** pulling in pressure opposing filtration
**0 mmHg - colloid osmotic pressure in bowman's capsule**
\* Net pressure favors filtration by about 10 mmHg!\*
Net Pressure = 42 mmHg - 32 mmHg
**_Net Pressure = 10 mmHg_**
59
What is Capillary Filtration Coefficient (Kf)?
**_Kf = Capillary Filtration Coefficient_**
A product of **permeability** and the **available filtering surface area** of capillaries. A measure of the product of the hydraulic conductivity and surface area of the glomerular capillaries.
\*\* Kf is usually HIGH to accomodate a HIGH hydrostatic pressure of the glomerular capillaries, THUS resulting in a HIGH GFR
**GFR** = Kf x Net Filtration Pressure
**GFR** = Kf x 10 mmHg
60
What is Capillary Filtration Fraction?
**Filtration Fraction** is the fraction of plasma filtered per minute
**Filtration Fraction** = GFR / Renal Plasma Flow
61
How do we figure out Renal Plasma Flow?
**_Renal Blood Flow_**
CO = 5000 ml/min, 20% is RBF
5000 x 0.2 = 1000 mL/min
**_Renal Plasma Flow_**
Average Hct = 45, and 55% is Plasma
1000 mL/min x 0.55 = 550 mL/min of Plasma
**_Filtration Fraction_** = GFR / Renal Plasma Flow
= 125 mL/min / 550 mL/min = **22%**
\*This is the percent of plasma filtered = Filtration Fraction
62
Why does the body need a HIGH GFR?
A HIGH GFR allows us to rapidly remove the waste & have precise control of volume and composition of ECF
\* This occurs 60x / Day
63
What are the different pressures in the Renal Corpuscle?
Glomerular Hydrostatic Pressure?
Bowman's Capsule Hydrostatic Pressure?
Glomerular Hydrostatic Pressure?
**_Net Filtration Pressure_** =
Glomerular Hydrostatic Pressure (60 mmHg)
-
Bowman's Capsule Hydrostatic Pressure (18 mmHg)
-
Glomerular Hydrostatic Pressure (32 mmHg)
= **10 mmHg**
64
How is the permeability of glomerular capillaries different from regular capillaries?
The permeability of glomerular capillaries is **50x** that of other capillaries
The glomerular capillary membrane is **THICKER** than most other capillaries, but it is also much **MORE POROUS** and therefore filters fluid at a high rate.
65
How does size relate to "filterability" when discussing permeability of glomerular capillaries?
**Molecular diameters \< 4 nm are freely filtered**
EX. Sodium and small organ compounds like glucose
**Molecular diameters \> 8 nm not filtered**
EX. Albumin not filtered at all
66
What is "Minimal Change Nephropathy"?
In certain kidney diseases, the negative charges on the basement membrane are lost even before there are noticeable changes in kidney histology.
As a result of this loss of negative charges on the basement membranes, some of the lower molecular weight proteins, especially albumin, are filtered and appear in the urine, a condition known as proteinuria or albuminuria.
EX. Nephritis (Kidney Disease)
67
Why is Albumin not filtered within the glomerulus?
The basement membrane of glomerular capillary has **NEGATIVE CHARGE**
Albumin has **NEGATIVE CHARGE** & this more than molecular size prevents albumin from being filtered.
Proteinuria results if charge on basement membrane is lost in disease (EX. Nephritis (Kidney Disease))
(small amount of protein that may show up in urine is epithelial cells shedding)
68
If a patient is having protein in their urine, what is the first cause that comes to mind?
If protein ends up in the urine, it usually means that there is **a problem with the basement membrane, and the negative charge on the basement membrane has been lost!**
69
Why isn't Albumin filtered within the glomerulous?
Most important reason albumin isn't filtered is **SIZE** but also **THE NEGATIVE CHARGE** that it carries!
**CHARGE IS MORE IMPORTANT THAN SIZE FOR FILTRATION**
70
What factors effect GFR?
Renal Blood Flow
Glomerular capillary hydrostatic pressure
Bowman’s capsule hydrostatic pressure
Glomerular capillary osmotic pressure
Changes in filtration coefficient
71
What is the autoregulation range of RBF and GFR?
**80 - 170 mmHg**
72
What percentage of body weight are the kindeys?
**1%**
73
What are the main RESISTANCE vessels of the Kidney?
**AFFERENT** & **EFFERENT** Arterioles
**\* If EITHER the Afferent or Efferent arteriles is contracted, it will REDUCE RBF**
74
Why does the kidney have such a HIGH RBF rate?
**RBF is 20% of CO**
**RBF is 10x more than required for metabolic rate**
It is this HIGH because we need to produce enough renal filtrate in order to eliminate waste products
75
What part of the kidney is perfused the MOST?
**_The CORTEX_**
This is where all of the Renal Corpuscles (glomeruli) are located
**HOWEVER, the blood flow to the medulla is EQUIVALENT to the blood flow to the brain!**
76
What happens to RBF during SNS stimulation?
**STRONG** SNS Activation causes **VASOCONSTRICTION** **of both afferent & efferent arterioles**
**=** ↓ Renal Blood Flow
= ↓ GFR
**MILD/MODERATE** SNS acitivation has **LITTLE EFFECT** on RBF or GFR
77
The SNS effect in DECREASING GFR is most significant when?
The SNS effect in DECREASING GFR is most significant with **SEVERE HEMORRHAGE**
Normal SNS stimulation in a healthy adult, rarely changes GFR
78
Can Acute Renal Failure due to iscemia be reversed?
**YES! As long as renal blood flow does not fall below 20% of normal**, acute renal failure can usually be reversed as long as the cause for ischemia is corrected before there is cellular damage
79
