Histo- urinary system Flashcards
The urinary system consists of:
1) Paired kidneys
2) Paired ureters
3) One urinary bladder
4) One urethra
functions of the urinary system:
1) Regulation of Blood Ionic Composition
2) Regulation of Blood Volume and Blood Pressure
3) Regulation of Blood pH
4) Conservation of Valuable Nutrients
5) Production and Secretion of Hormones (Endocrine Function)
6) Assisting the Liver in Detoxification of Poisons
7) Elimination of Organic Waste Products and Foreign Substances
The hilum of the kidneys
- the deep vertical fissure along the medial concave border of the kidney
- where renal vessels, nerves, and renal pelvis pass into/out of the kidney.
what is found Just past the hilum of the kidney
an internal space called the renal sinus
the renal sinus:
filled with loose connective tissue and adipose tissue, along with part of the renal pelvis, the calyces, and branches of the blood vessels and nerves.
The kidneys surface is covered by a connective tissue capsule called what?
the renal capsule.
what is the parenchyma?
the functional part of the kidney
what are the 2 regions of the parenchyma?
1) the renal cortex
2) the renal medulla
the Renal Medulla is divided into what?
1) renal pyramids
2) renal columns
what is the structure of the renal pyramids?
A) 6-18 distinct conical or triangular structures
B) the base faces the cortex
C) the apex is the renal papilla
where are the renal columns found? what is it made of?
- in between pyramids
- cortical tissue within medulla
what is a renal lobe composed of?
consists of a renal pyramid, its overlying renal cortex, and one-half of each adjacent renal columns
what is a nephron?
the fundamental structural and functional unit of the kidney.
A nephron consists of two parts:
(1) a renal corpuscle
(2) a renal tubule.
where does glomerular filtration occur?
the renal corpuscle
where does tubular reabsorption and tubular secretion occur
renal tubules
nephron + collecting tubule =
uriniferous tubule
Each nephron will drain into what?
a collecting tubule
For urine to be produced, the nephrons perform three processes:
1) Glomerular filtration
2) Tubular reabsorption
3) Tubular secretion
Glomerular filtration
first step; water and most solutes in blood plasma move from the glomerular capillaries into the glomerular (i.e. Bowman’s) capsule.
Tubular reabsorption
- Filtered fluid then moves through the renal tubule
- the tubule cells reabsorb ~99% of filtered water and many solutes
- these items return to the blood at the peritubular capillaries.
Tubular secretion
The tubule cells can remove additional substances (ex. wastes, drugs, and excessive ions) from the blood in the peritubular capillaries.
what is the beginning of the nephron? Where is it located?
- Renal corpuscle
- located in the renal cortex.
The two components of a renal corpuscle
(1) the glomerulus and
2) Bowman’s capsule (a.k.a. glomerular capsule
The glomerulus
- a tuft of capillaries composed of 10 to 20 capillary loops
- supplied by an afferent arteriole and drained by an efferent arteriole
layers of the bowman’s capsule
Visceral layer of Bowman’s capsule – internal layer
Parietal layer of Bowman’s capsule – external layer
the first part of the renal tubule
the proximal convoluted tubule
Visceral layer of the Bowman’s capsule
A) internal layer
B) modified simple squamous epithelial cells called podocytes
C) extensions of these cells (pedicels) will wrap around the single layer of endothelial cells of the glomerular capillaries
filtration slits (bowman’s capsules)
A) is where the ultrafiltrate from the blood enters Bowman’s space
B) covered by the slit diaphragm
Parietal Layer of the Bowman’s capsules
external layer; simple squamous epithelium.
A renal tubule consists of what?
A) a proximal convoluted tubule (PCT)
B) the loop of Henle (nephron loop)
C) the distal convoluted tubule (DCT).
The renal tubule is where what occurs?
tubular reabsorption and tubular secretion occurs.
Proximal Convoluted Tubule –
attaches to the glomerular capsule; highly coiled tube; lies within the renal cortex.
Loop of Henle
extends from the renal cortex into the renal medulla, turns, and returns to cortex.
Distal Convoluted Tubule –
last part of the renal tubule; highly coiled tube; lies within the renal cortex; the distal convoluted tubule empties into a collecting tubule.
histological differences between proximal and distal convoluted tubules:
1) the proximal convoluted tubules have a larger outside diameter
2) their cytoplasm stains a little pinker (due to mitochondria)
3) their cells are larger so there are fewer nuclei around the lumen as compared to the distal convoluted tubules
Nephron Loop (a.k.a. Loop of Henle) is composed of
1) Thick descending limb of the loop of Henle (a.k.a. proximal straight tubule)
2) Thin descending limb of the loop of Henle
3) Thin ascending limb of the loop of Henle
4) Thick ascending limb of the loop of Henle (a.k.a. distal straight tubule)
Thick descending limb of the loop of Henle (a.k.a. proximal straight tubule) is composed of what
composed of simple cuboidal epithelial cells.
Thin descending limb of the loop of Henle is composed of what
composed of simple squamous epithelial cells.
Thin ascending limb of the loop of Henle is composed of what
composed of simple squamous epithelial cells.
Thick ascending limb of the loop of Henle (a.k.a. distal straight tubule) is composed of what
composed of simple cuboidal epithelial cells
Distal Convoluted Tubule (DCT)
- found in the cortex
- lined with simple cuboidal epithelium
- Lots of mitochondria
The final part of the ascending limb of the loop of Henle comes in contact with what?
comes in contact with the afferent arteriole from the same nephron
what is the macula densa?
a region where the cells are crowded together and become columnar with apical nuclei.
what are juxtaglomerular cells
modified smooth muscle cells in the walls of the afferent arteriole
Macula and Juxtaglomerular cells form what?
Juxtaglomerular Apparatus (JGA)
The juxtaglomerular apparatus helps to regulate what?
blood pressure within the kidneys
what is the path of urine starting at the minor calyx?
From minor calyx To major calyx To renal pelvis To ureter To urinary bladder To urethra To toilet
collecting tubules unite into larger collecting ducts which then merge near the apex of the pyramid to form what?
papillary ducts (ducts of Bellini)
what is the muscularis layer of the Calyces, renal pelvis, ureter, and urinary bladder
Muscularis layer: Smooth muscle A) Inner longitudinal layer B) Outer circular layer C) Outermost longitudinal layer (distal end of ureter and present in bladder)
Male urethra- the 3 parts, and what type of epithelium they are made of
A) prostatic urethra- lined with urothelium
B) Membranous urethra- lined by stratified columnar epithelium and pseudostratified columnar epithelium
C) Spongy Urethra – lined stratified columnar epithelium and pseudostratified columnar epithelium
female urethra- what is it lined with?
Lined initially by urothelium then by stratified squamous epithelium, with the occasional pseudostratified columnar epithelium.
