1
Q
Structures of the Urinary System
A
- 2 Kidneys
- 2 Ureters
- 1 Urinary bladder
- 1 Urethra
2
Q
Functions of Urinary System (Regulates)
A
- Blood volume
- Blood pressure
- pH (concentrations of H+ and HCO3-)
- Concentrations of each ion in the blood (Na+, Ca++, K+, Cl-)
- Secretion of renal hormones
3
Q
Functions of Urinary System (Eliminates)
A
- Wastes e.g. urea, uric acid
- Hormones
- Drugs (e.g. antibiotics)
- Toxins
4
Q
Structures of the Urinary System
A
- Kidneys
- Nephrons
- Juxtaglomerular Complex (Apparatus)
- Ureters
- Urinary Bladder
- Urethra
5
Q
Kidneys
A
- External Anatomy of Kidneys
- Internal Anatomy of Kidneys
6
Q
External Anatomy of Kidneys
A
- Retroperitoneal
- Right lower than left
- Supported and protected by 3 layers of connective tissue
- Renal Hilus (Hilum)
7
Q
3 Layers of Connective Tissue (External Anatomy - Kidney)
A
- Fibrous Capsule
- Outer layer
- Perirenal Fat Capsule
- Middle layer
- Renal Fascia
- Inner layer
8
Q
Renal Hilus (Hilum)
A
- Medial indentation
- Entry point of:
- Renal artery (superior)
- Renal Vein (Inferior)
- Ureter
- Nerves
9
Q
Internal Anatomy of Kidneys
A
- Renal Cortex (superficial layer)
- Renal Medulla
- Renal Pelvis
10
Q
Renal Cortex (superficial layer)
A
- Contains parts of nephrons
- Contains afferent and efferent arterioles as well as capillary beds called glomeruli
11
Q
Renal Medulla
A
- Renal pyramids
- Renal Columns
12
Q
Renal pyramids
A
- Apex of pyramid is called the renal papilla
- Contain parts of nephrons
13
Q
Renal Columns
A
- Projections of cortex into the medulla
- Separate pyramids
- Contains arteries, veins and nerves that supply the cortex
14
Q
Renal Pelvis
A
- Central collecting chamber for filtrate/urine
- Receives filtrate/urine from major calyces
- Major calyces receive filtrate/urine from minor calyces which are small cup shaped structures that surround the renal papilla
15
Q
Nephron
A
- Functional unit of kidney (microscopic)
- Composed of:
- Renal Corpuscle
- Renal Tubules
16
Q
Renal Corpuscle
A
- In cortex
- Site of blood filtration (first step in urine formation)
- Parts:
- Glomerulus
- Afferent Arteriole - enters glomerulus
- Efferent Arteriole - exits glomerulus
- Glomerular (Bowman’s) Capsule
17
Q
Glomerulus
A
- = Capillary bed (endothelium formed of simple squamous epithelium)
- Has many fenestrations (pores) between cells
18
Q
Afferent Arteriole - enters glomerulus
A
Carries blood delivered to kidney from the renal artery
19
Q
Efferent Arteriole - exits glomerulus
A
Drains into peritubular (of cortical nephrons) and vasa recta (of juxtaglomerular nephrons)
20
Q
Glomerular (Bowman’s) Capsule
A
- Surrounds and collects filtrate (filtered blood plasma) from glomerulus
- 2 layers:
- Outer layer is a simple squamous epithelium
- Inner layer is made of cells called podocytes that wrap around glomerular capillaries
21
Q
What does the Filtration Membrane consists of?
A
- Glomerular endothelium (capillaries)
- Fenestrations in the simple squamous epithelium allow plasma through, but not formed elements and most large proteins
- Shared basement membranes of i) and iii)
- Podocytes (of glomerular capsule)
- Have many finger-like projections that form a network of filtration slits
22
Q
Renal Tubules
A
- 4 parts with specific cell types and functions:
- Proximal Convoluted Tubule (PCT)
- Nephron Loop
- Distal Convoluted Tubule (DCT)
- Collecting Ducts
23
Q
Proximal Convoluted Tubule (PCT)
A
- In cortex
- Receives filtrate from glomerular capsule
- Cells are cuboidal epithelium with dense microvilli
- Reabsorbs most useful substances (e.g. glucose, amino acids) from the filtrate
- Secretes waste products into filtrate
24
Q
Nephron Loop
A
- In the medulla
- Descending limb (thin)
- Simple squamous epithelium, highly water permeable
- Ascending limb (thick)
- Simple cuboidal epithelium, water-impermeable
25
Distal Convoluted Tubule (DCT)
- In cortex
- Cuboidal epithelium
26
Collecting Ducts
- In cortex & medulla
- Drain filtrate from numerous nephrons into minor calyces
- Contain cells that regulate water and Na+ reabsorption and acid/base balance of the blood
27
2 Types of Nephrons
1. Cortical
2. Juxtamedullary
28
Cortical
- Make up majority of nephrons
- Renal corpuscles near kidney surface in cortex
- Short nephron loop that dips into the outer medulla
- Has peritubular capillaries that branch from efferent arteriole and surround DCT and PCT
29
Juxtamedullary
- Renal corpuscles in cortex near medulla
- Long nephron loops that penetrate deep into medulla
- Allow for production of dilute or concentrated urine depending on need
- Has capillaries that branch from efferent arterioles called vasa recta that run parallel to the nephron loop
30
Juxtaglomerular Complex (apparatus)
- Regulates the rate of filtrate formation
- Point of contact between end of ascending limb, afferent and efferent arterioles at renal corpuscle of same nephron
- Parts
1. Tubular Portion - macula densa
2. Vascular (Arteriolar) Portion
31
Tubular Portion - macula densa
- Modified (tall and narrow) distal convoluted tubule cells
- Monitor filtrate composition
32
Vascular (Arteriolar) Portion
- Afferent and efferent arteriolar portion = granular (juxtaglomerular cells)
- Modified smooth muscle cells that monitor blood pressure
- Secrete an enzyme/hormone that helps to regulate blood pressure and ion balance
33
Ureters
- Transports urine from renal pelvis to bladder
- Retroperitoneal
34
Histology (Ureters)
- Mucosa
- Transitional epithelium (stretches)
- Muscularis Externa
- Smooth muscle
- Adventitia
- Connects ureter to body wall
35
Urinary Bladder
- Short term storage of urine
- Retroperitoneal
36
Histology (Urinary Bladder)
- Mucosa
- Transitional epithelium with rugae
- Muscularis externa
- = Detrusor muscle - smooth muscle
- Contraction of detrusor muscle causes urination
- Adventitia/Serosa
- Mostly adventitia
- Serosa covers the superior surface
37
Urethra
- Drains urine from bladder
- Transports urine and when testes are present, also transports semen
38
Histology (Urethra)
- Mucosa
- Transitions from transitional epithelium to stratified squamous epithelium
- Muscularies externa
- Is smooth muscle
- Adventitia only
39
2 Sphincters (Urethra)
1. Internal urethral sphincter (smooth muscle)
- Thickening of detrusor muscle at base of bladder
2. External urethral sphincter (skeletal muscle)
- In urogenital diaphragm
40
Filtrate Movement of the Urinary System
Several DCTs
↓
Collecting ducts (exit at renal papilla)
↓
Minor Calyx
↓
Major Calyx
↓
Renal Pelvis
↓
Ureter
↓
Urinary Bladder
↓
urethra
41
Related Medical Conditions
1. Urinary Tract Infection (UTI)
2. Glomerulonephritis
42
Urinary Tract Infection (UTI)
Bacterial infection of the mucosa of the bladder and/or urethra (most common). Can also involve ureters and kidneys (less common).
43
Glomerulonephritis
Inflammation of the glomeruli ans structures of the filtration membrane that impairs their ability to filter blood plasma
FINAL EXAM - BIOL 1410
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