Practical #4 Flashcards
Urinary System Functions
forms urin and stores it until it is eliminated from the body (micturition)
Components of the Urinary System
- kidneys
- ureters
- urinary bladder
- urethra
Where are the kidneys located?
- waist level between 12th thoracic vertebra and 3rd lumbar vertebra
- retroperitoneal
Functions of the kidneys
- reg of blood ionic composition
- reg of blood pH
- reg of blood volume
- reg of blood pressure
- maintenance of blood osmolarity
- production of hormones
- regulation of blood glucose levels
- excretion of wastes and foreign substances
Layers of kidney external anatomy (deep to superficial)
- renal capsule
- adipose capsule
- renal fascia
Renal capsule
- thin, fibrous membrane
- covers outer surface of the kidneys
Adipose capsule
- adipose tissue
- between renal capsule and renal fascia
- provides protection and padding (cushion)
Renal fascia
- dense irregular connective tissue
- outermost layer that attaches kidney to abdominal wall
Renal hilum
- indentation at the concave border
- ureter, renal artery, renal vein, nerves, and lymphatic vessels pass through
Layers of kidney internal anatomy (superficial to deep_
- renal cortex
- renal medulla
- renal sinus
Parts of renal medulla
- renal pyramids
- renal columns
- portion of nephrons
- papillary ducts
- renal papilla
Parts of renal sinus
- minor calyx
- major calyx
- renal pelvis
Renal cortex
- contain portion of the nephrons
- contain a portion of the renal columns
Renal pyramids
cone shaped
Renal columns
extend from renal cortex and separate renal pyramids
Papillary ducts
openings in renal papilla that drain urine
Renal papilla
apex of renal pyramid that is pointed towards renal sinus
Minor calyx
adjacent to renal papilla; receive urine from papillary ducts
Major calyx
many minor calyces drain urine into a major calyx
Renal pelvis
large cavity that major calyces drain into; continuous with ureter
Blood flow through kidneys
- renal artery
- segmental arteries
- interlobar arteries
- arcuate arteries
- interlobular arteries
- afferent arterioles
- glomerular capillaries
- efferent arterioles
- peritubular capillaries
- interlobular veins
- arcuate veins
- interlobar veins
- renal vein
Ureters
- 2 long, narrow muscular tubes
- extend from each kidney to the urinary bladder
- transport urine from kidneys to urinary bladder
- enter the inferior posterior wall of the bladder at an oblique angle
- urine propelled through ureters by peristalsis, hydrostatic pressure, and gravity
Urinary Bladder
- hollow muscular organ
- distends to store urine and expels it into urethra
- detrusor muscle
- rugae
- tirgone
- internal urethral orifice
Detrusor muscle
smooth muscle within wall of bladder; contracts to force urine out of bladder
Rugae
folds in epithelial lining of bladder
Trigone
- funnel shaped
- 2 urethral openings and internal urethral orifice
Internal Urethral Orifice
anterior opening into urethra
Urethra
- tube carrying urine from internal urethral orifice to the exterior of the body
- discharges urine from the body
- external urethral orifice
- internal urethral sphincter
- external urethral sphincter
External Urethral Orifice
opening through which urine exits the body
Internal Urethral Sphincter
involuntary smooth muscle that controls passage of urine from urinary bladder to urethra
External Urethral Sphincter
voluntary skeletal muscle that permits passage of urine to external urethral orifice
Male Urethra Length and Regions
- long (15-20 cm)
- has 3 regions: prostatic urethra, membranous urethra, spongy (penile) urethra
Prostatic urethra
prostate gland
Membranous urethra
urogenital diaphragm
Spongy (penile) urethra
penis
Female Urethra Length
short (4 cm)
Nephron
- functional unit of the kidney
- contains renal corpuscle, renal tubule, and collecting ducts
Renal corpuscle
- filters blood
- located in renal cortex
- contains glomerulus, glomerular capsule, capsular space
Glomerulus
capillary network
Glomerular (Bowman’s) capsule
cup-shaped epithelial membrane surrounding glomerulus
Capsular space
- glomerular cavity between glomerulus and Bowman’s capsule
- where filtrate enters
Renal tubule
- modifies filtrate to form urine
- contains proximal convoluted tubule, loop of henle, distal convoluted tubule
Proximal convoluted tubule
located in renal cortex
Loop of Henle (nephron loop)
- extends into renal medulla
- has ascending and descending limb of loop of henle
Distal convoluted tubule
located in renal cortex
Collecting ducts
- many distal convoluted tubules converge here
- many collecting ducts unite into papillary ducts
Where does filtration occur?
renal corpuscle
Where does reabsorption occur?
renal tubule and collecting duct
Where does secretion occur?
renal corpuscle and collecting duct
What affects the amount of filtrate?
diameter of afferent arteriole and pressure within glomerular capillaries
Types of nephrons
Cortical nephrons and Juxtamedullary nephrons
Cortical nephrons
- majority of nephrons
- short loops of henle: descend slightly into medulla
- receive blood supply from peritubular capillary network
Juxtamedullary nephrons
- PCT, Corpuscle, DCT: closer to medulla
- long loops of henle: descend deep into medulla
- 2 portions of ascending limb: thin and think ascending limb
- receive blood supply from peritubular capillary network AND vasa recta
Flow of Filtrate/Urine through Urinary System
I don’t know
Kidney Histology
- glomerular (bowman’s) capsule
- proximal convoluted tubule
- loop of henle
- distal convoluted tubule
- collecting ducts
Glomerular (Bowman’s) Capsule
- visceral epithelial layer
- parietal epithelial layer
- podocytes
Visceral epithelial layer
filtration membrane adjacent to glomerulus (simple squamous epithelium)
Parietal epithelial layer
forms funnel-like structure that collects filtrate in capsular space (simple squamous epithelium)
Podocytes
foot-like projections on visceral layer that wrap around glomerular capillaries
Proximal convoluted tubule
simple cuboidal epithelium
Loop of Henle
- descending limb
- ascending limb (thin and thick sections)
Descending Limb (loop of henle)
simple squamous epithelium
Ascending limb thin section (loop of henle)
simple squamous epithelium
Ascending limb thick section (loop of henle)
simple cuboidal epithelium to low columnar cells
Distal convoluted tubule
simple cuboidal epithelium
Collecting ducts
simple cuboidal epithelium
Ureters, Urinary Bladder, Urethra Histology
- mucosa (epithelium and lamina propria)
- muscularis (inner longitudinal and outer circular)
- adventitia
Ureter and Urinary Bladder histology
mucosa contains transitional epithelium (distends to accomodate urine)
Urethra histology
- transitional epithelium to stratified columnar epithelium
- pseudostratified columnar epithelium to stratified squamous epithelium
Urinalysis
analysis of the physical, chemical, and microscopic characteristics of urine and measures urine volume
Specific gravity
- the weight of a volume of substance divided by the weight of the same volume of distilled water
- indicates the amount of “stuff” in substance
- urine’s SG ~1.001-1.035
Osmolarity
a measure of the total number of dissolved particles per liter of solution
Normal volume of urine
one to two liters per 24 hours; considerable variation in normal volume
Normal color of urine
yellow or amber color; urine color is darker in concentrated urine
Normal turbidity of urine
transparent in freshly voided urine; will turn cloudy after standing; microbes, pus, epithelial cells, or crystals may cause cloudiness in fresh urine
Normal oder of urine
aromatic when fresh; ammonia-like after standing because of breakdown of urea to ammonia by bacteria
Normal pH of urine
normal range is 4.6-8.0, with an average of 6.0; high-protein diets produce an acidic urine; vegetarian diets produce alkaline urine
Normal specific gravity of urine
normal range is 1.001-1.035; low specific gravity represents dilute urine; higher values represent a concentrated urine
Urea levels in urine
byproduct of protein catabolism normally found in the urine; excessive excretion of urea may be indicative of an abnormal increase in protein degradation that could lead to muscle wasting and negative nitrogen balance
Creatinine levels in urine
a metabolite of creatine phosphate catabolism in muscle; creatinine is a normal constituent of the blood and urine
Uric acid levels in urine
formed in the catabolism of nucleic acids (DNA and RNA); uric acid is very insoluble and tends to crystallize, contributing to the production of kidney stones
Ammonia levels in urine
a product of protein catabolism that is either excreted in the urine or is used as a substrate to form urea; like urea, excessive ammonia excretion may reflect abnormal levels of protein degradation