Urinary Histo Flashcards
Exocrine function (4)
- Removes metabolic wastes and foreign substances
- Regulates body fluid
- Regulates body salt content
- Controls acid-base balance
Endocrine function (3)
- Renin secretion: regulation of blood pressure
- Erythropoietin secretion: stimulates production of red blood cells
- Controls calcium metabolism by activating 1,25-(OH)2: vitamin D3
Gross anatomy of kidney
- bean shaped
- connected to blood vessels and ureter
2 regions of anatomy of kidney
Cortex: outer, reddish area
which receives ~ 90% - 95% of
the blood passing through the
kidney
Medulla: inner, lighter colored
Regions of kidney labeled
Portions of cortex
- Cortical labyrinth (area with corpuscles)
- Medullary ray (same tissue as medulla)
Portions of cortex labeled
Number of lobes: major and minor calyces
major: 2-3
minor: 5-11
How many lobes do humans have?
8-12 lobes per kidney (3-4 are sufficient for life)
Lobe labeled
What are lobes divided into?
Lobules
What does a lobule consist of?
- medullary ray (center)
- surrounding cortical material
Lobule structure image
What does a renal secretory duct consist of?
- collecting duct
- group of nephrons that drain into that duct
What is the functional unit of the kidney?
Nephron
2 types of nephrons:
- juxtamedullary
- cortical
What gives the layers and striations in a hemi-sected kidney?
Arrangement of the tubules
Filtration units (4)
- Renal corpuscle: glomerulus, Bowman’s cap
- Proximal thick: convoluted and thick
- Distal thick: convoluted and thick
- This segment: descending, ascending
Filtration units in the cortex (2)
- cortical labyrinth
- medullary ray
Filtration units in the medulla
- outer medulla (o)
- outer medulla (i)
- inner medulla
cortical labyrinth segments
- renal corpuscles
- PCT
- DCT
medullary ray segments
- PST
- DST
- CD
outer medulla (o)
- PST
- DST
- CD
outer medulla (i)
- thin seg of Henle’s Loop
- DST
- CD
inner medulla
- thin seg of Henle’s Loop
- CD
Which 2 segments of the nephron have the same composition?
Medullary Ray and Outer Medulla (outer stripe):
- PST
- DST
- CD
Juxtamedullary vs Cortical Image
Renal corpuscle poles
Renal corpuscle image
Bowman’s capsule layers:
– parietal layer, simple squamous
– visceral layer, podocytes w/ foot processes (pedicels)
– bowman’s space (urinary/capsular space)
Renal corpuscle layer formation
Renal corpuscle image
Visceral/podocyte image
Filtration Apparatus Components (3)
- Glomerular capillary endothelium
- Glomerular basement membrane
- Visceral/podocyte layer of Bowman’s capsule
Filtration Apparatus EM
Filtration Apparatus EM
FA: Glomerular Capillary Endothelium
- fenestration diameter
- lacks a diaphragm
- aquaporin-1 water channels
- thick glycocalyx on the luminal side
FA: Glomerular Basement Membrane
- physical & charge barrier
- 3 areas:
1. lamina rara interna
2. lamina densa
3. lamina rara externa
FA: Visceral Layer of Bowman’s Capsule
- contains podocytes
- cells are coated with podocalyxin (negatively charged)
- podocytes extend processes that surround the capillaries
Podocyte slit diaphragms EM
Slit diaphragms EM
What is the purpose of slit diaphragm?
- increase filtering power of the podocyte
What type of junction is the slit diaphragm?
modified adherens junction
Which transmembrane protein is associated with the slit diaphragm?
Nephrin contributes to the structure and function of the diaphragm
Mutations in the nephrin gene?
- congenital nephrotic syndrome
- blood in urine
Filtration Apparatus Summary
- Glomerular capillary endothelium -
water channels, size, and ion barrier - Glomerular basement membrane –
physical barrier and an ion-selective filter - Podocytes – filtration slit membrane =
physical barrier (true size-selective barrier)
Mesangium refers to
mesangial cells and extracellular matrix between the glomerular capillaries
Where are mesangial cells most evident?
vascular pole
What are extraglomerular mesangial / lacis cells?
mesangial cells that are located outside of the renal corpuscle
Lacis and mesangial cells image