Chapter 26 - Urinary System Flashcards
Kidney functions (8)
**Regulation of: **
blood ionic composition, pH, volume, pressure, glucose level
**Maintenance of **blood osmolarity
**Production of **hormons (calcitrol & erythropoitin)
**Excretion of **wastes from metabolic reactions & foreign substances
External Anatomy of Kidneys
**Renal Hilum **
**3 layers of tissue **
Renal Hilum
(3) layers of tissue
-
indent where ureter emerges along with blood & lymphatic vessels & nerves
1) renal capsule
2) adipose capsule
3) renal fascia
1) renal capsule
2) adipose capsule
3) renal fascia
1) deep layer - continous with coat of ureter, barrier against trauma & maintains kidney shape
2) mass of fatty tissue, protects kidney from trauma & holds it in place
3) superficial layer - thin layer of CT that anchors kidney to surrounding structures & abdominal wall
Kidney - position, weight & size
retroperitoneal
level of T12 to L3
160g each
size of bar of soap
Kidney shape
**lateral surface - **convex
**medial border- **concave: faces vertebral column
- renal hilum near center
Connective tissue coverings
1) renal capsule (deep)
2) adipose capsule
3) renal fascia (superficial)
1) encloses kidney like cellophane wrap
2) cushions kidney
3) binds to abdominnal wall
(2) distinct regions of kidney
superficial, light red - Renal cortex
deep, darker reddish-brown - **Renal medulla **
**Renal Cortex **
extends from?
consists of
superficial
extends from renal capsule to bases of renal pyramids
divided into (2) zones
**renal columns **
(2) zones of renal cortex
**Outer cortical zone **
Inner juxtamedullary zone
Renal cortex
- renal columns
portions of renal cortex that extend between renal pyramids
**Renal Medulla **- inner region
consists of?
several cone-shaped **renal pyramids **
base (wider end) faces renal cortex,
apex (narrow end) = **renal papilla **- points toward renal hilum
Renal lobe
consists of **renal pyramid, **overlying area of **renal cortex **& 1/2of each adjacent renal column
Parenchyma of kidneys = ?
FUNCTIONAL PORTION OF KIDNEYS
renal cortex + renal pyramids of renal medulla
Nephrons
microscopic functional unit of kidney
filtered fluid formed by **nephrons **drains into?
large **papillary ducts - **extend through renal papillae of renal pyramids
Flow of filtered fluid from nephrons
→ papillary ducts → minor calyces (8-18) → major calyces (2-3) → renal pelvis → ureter → urinary bladder
When does filtrate become urine? why?
once filtrate enters calyces
because no further reabsorption can occur
b/c simple epithelium of nephron & ducts becomes transitional epithelium in calyces
Renal sinus
cavity within kidneys that hilum expands into
contains part of renal pelvis, calyces, branches of renal blood vessels & nerves
Although kidneys constitute less than 0.5% of total body mass, they
receive 20-25 % of resting cardiac output via?
right & left **renal arteries **
Within kidneys, **renal arteries **divide into…
segmental arteries →interlobar → arcuate → interlobular→ afferent arterioles → glomerulus → efferent arteriole→ peritubular capillaries + vasa recta → peritubular venules→ interlobular veins →arcuate → interlobar →renal vein
each ___ recieves one **afferent arteriole, **which divides into tangled ball-shaped capillary network called ___?
**glomerulus **
LOCATION OF:
1) segmental arteries →
2) interlobar →
3) arcuate →
4) interlobular →
5) afferent arterioles →
6) glomerulus
1) within kidney
2) in parenchyma, through renal columns, b/w renal pyramids
3) base of renal pyamid, arch b/w medulla & cortex
4) pass b/w renal lobules
5) renal cortex
6) nephron recieves 1 afferent arteriole which divides into **glomerulus **
**Glomerular **capillaries reunite to form **efferent arterioles **which divide to form → __ __ → __ _→_ _→___→__→__ ___ → __ ___ __
extending from some **efferent arterioles **are ___ ___
efferent arteriole → peritubular capillaries (surround tubular part of nephrons in cortex)→ peritubular venules → interlobar veins → arcuate → interlobar → renal vein → exits through renal hilum → **inferior vena cava **
**vasa recta **- long loop-shaped capillaries that support tubular portions of nephron in medulla
Renal nerves are part of the ___ ___ nervous system
most are __ nerves regulating?
sympathetic autonomic
**vasomotor **- regulate blood flow through kidney by vasodilation/constriction of renal arterioles
Nephron
- (2) parts
1) Renal **corpuscle **
2) Renal **tubule **
Parts of Nephron:
1) Renal corpuscle
2) Renal tubule
1) where blood plasma is filtered
2) into which filtered fluid passes
Nephron
(2) components of renal corpuscle
a) **glomerulus **
b) glomerular (Bowman’s) capsule
Nephron: renal **corpuscle **
**a) glomerulus **
b) glomerular (Bowman’s) capsule
a) capillary network
b) double-walled epithelial cup that surrounds glomerular capillaries
Blood plasma is filtered in **golumerular capsule, **then passed into renal tubule.
(3) main sections of RENAL TUBULE
- *in order that fluid passes through them *
1) proximal convulated tubule (PCT)
2) **loop of Henle (nephron loop) **
3) distal convulated tubule
**renal corpuscle **& both convulated tubules lie within ____ ___
**Loop of Henle **extends into __ __ but returns to renal cortex
renal cortex
renal medulla
**Distal convoluted tubule **of several nephrons empty into?
a single **collecting duct **
Urine flow:
Distal convoluted tubules → ? → ? ….
**collecting duct **→ converge into 100s of **papillary ducts → minor calyces **
**collecting ducts & papillary ducts **extend from? through? to?
renal cortex through medulla to renal pelvis
**Loop of Henle **in nephron connects?
(2) parts of **Loop of Henle **
proximal & distal convoluted tubules.
into renal medulla as 1) descending limb
makes hairpin turn and returns to renal cortex as
2) **ascending **limb
(2) types of Nephrons
1) Cortical
2) Juxtamedullary
1) Cortical Nephron
location of renal corpuscles
**Loop of Henle **structure
80-85% of nephrons
**renal corpuscles **lie in outer portion of renal cortex (cortical zone)
short loops of Henle - mainly in cortex, penetrate only into outer region of renal medulla
the short **Loops of Henle **in **Cortical Nephrons **recieve blood supply from..?
**peritubular capillaries **that arise from **efferent arterioles **
**Juxtamedullary **nephrons
location of **Renal corpuscle **
**Loop of Henle **structure
- ascending limb
15-20% of nephrons
renal corpuscles lie deep in cortex (juxtamedullary zone)
long **Loop of Henle - **extends into deepest region of medulla
(2) portions off **ascending limb **- thin & thick
Long **loops of Henle **in **Juxtamedullary Nephrons **recieve blood supply from?
**peritubular capillaries & **vasa recta **that arrise from efferent arterioles
Histology of Glomerular capsule
(2) layers
1) parietal layer
2) visceral layer
Glomerular Capsule
1) parietal layer
2) visceral layer
1) simple squamous epithelium - **outer wall **
2) modified simple squamous epithelium = **podocytes **that wrap projections around single layer of endothelial cells of **glomerular capillaries **
- inner wall
Fluid filtered from glomerular capillaries enters…
**Glomerular (Bowman’s) space - **space between 2 layers of glomerular capsule (lumen of urinary tube)
Histology of Renal Tubule & Collecting duct
- PROXIMAL CONVOLUTED TUBULE
simple cuboidal epithelial cells
prominent brush borderof microvilli on surface facing lumen
Histology of** Renal Tubule & Collecting duct**
**DESCENDING & **1ST PART OF ASCENDING LIMB OF LOOP OF HENLE (THIN)
**descending & thin ascending - **simple squamous epithelium
**thick - **simple cuboidal to low columnar epithelium
Macula densa
area of closely packed specialized cells lining the wall of the distal convoluted tubule/final part of ascending loop of henle
Juxtamedullary cells
modified smooth muscle fibers in walls of afferent (& sometimes efferent) arterioles alongside macula densa
Juxtamedullary Apparatus
macula densa + juxtamedullary cells
- help regulate blood pressure in kidney
In the last part of the Distal Convoluted Tubule & continuing into **collecting ducts, **
(2) different types of cells are present
1) **principal cells - **receptors for antidiuretic hormone (ADH) & aldosterone (2 hormones that regulate their functions)
2) **intercalated cells - **play a role in homeostasis of blood pH
(3) basic processes performed by **nephrons & collecting ducts **to produce urine
1) GLOMERULAR FILTRATION
**2) TUBULAR REABSORPTION **
3) TUBULAR SECRETION
**1) GLOMERULAR FILTRATION **
2) TUBULAR REABSORPTION
3) TUBULAR SECRETION
1) water & solutes in blood plasma move across wall of glomerular capillaries, filtered → move into glomerular capsule → renal tubule
2) as filtered fluid flows through **renal tubules → collecting ducts **- tubule cells reabsorb 99% of filtered water & other solutes which return to blood as it flows through **peritubular capillaries & vasa recta **
3) as filtered fluid from **renal tubules + collecting ducts, **renal tubule & duct cells secrete other materials (waste, drugs, xs ions) into fluid
solutes in fluid that drain into renal pelvis remain in fluid and are ___ as ___
excreted as urine
Excretion of any solute = ?
glomerular filtration - reabsoprtion + secretion
Urinary bladder
hollow ditensible muscular organ
capacity: 700-800 mL
Micturition
discharge of urine from urinary bladder
aka urination
**Urination/Micturition **involves combination of?
voluntary & involuntary muscle contractions
When volume of urine in urinary bladder exceeds 200-400 mL, pressure increases &…
stretch receptors in wall transmit nerve impulses into spinal cord → micturition **center **in S2 & S3 → trigger (spinal reflex) micturition reflex → parasympathetic impulses to **urinary bladder & internal urethral sphincter → **contraction of detrusor, relaxation of **internal urethral sphincter + **inhibition of somatic motor neurons in external urethral sphincter
External urethral orifice
between clitoris & vaginal orifice
Internal urethral sphincter
detrusor muscle thickened, smooth muscle, involuntary control
