Human Anatomy- Chapter 24- The Urinary System
Micturition
(Voiding or urination) the act of emptying the bladder
1. Nephron
A urine forming nephron consisting of renal corpuscle ( filtration happens) a proximal convoluted tubule, a loop of Henle, and a distal convoluted tubule.
Renal hilus
A vertical cleft located on the medial surface where renal blood vessels, ureters, lymphatic and nerves enter and leave the kidney
Why is the Trigone clinically important
Because infections tend to persist in this region
Contraction squeezes urine from the ___ during __
Bladder, urination
The distal ends of the ureters ___ in response to any ___ of pressure within the ___ to prevent __
Close, increase, bladder, back flow of urine
1. Mucosa
Composed of a transitional epithelium that stretches when the ureters fill with urine and a lamina propria composed of a stretchy, fibroelastic c.t
1. Proximal tubule
Composed of cuboidal cells with numerous Microvilli and mitochondria, reabsorbs water and so lutes from filtrate and secrets substances into the loop of Henle - confined entirely to the renal cortex
2. Muscularis
Consists of 2 layers : an inner longitudinal layer and a circular layer of smooth muscle
2. Adipose capsule
Consists of perirenal fat and just external to that is an envelope of renal fascia
The broad base of each pyramid abuts the
Cortex
3. Distal convoluted tubule
Cuboidal cells without Microvilli that function more in secretion than reabsorption - confined to the renal cortex
Minor calices
Cup shaped tubes that enclose the papillae of the pyramids
The perirenal fat layers function to
Cushion the kidney against blows and help hold the kidney in place
2. Collecting duct
Involved in concentrating urine by removing water from it - dumps at minor calyx
Nephron
Is the basic structural and functional unit of the kidney.
Urethra
Is thin-walled that drains urine from the bladder and conveys it out of the body
Nephron- chief function
Is to regulate the concentration of water and soluble substances like sodium salts by filtering blood, reabsorbing what is needed and excreting the rest as urine
Bowmans capsule- inner layer
Is very porous to extract and absorb plasma for the glomerulus
How is the glomerulus different from all other capillary beds in the body
It is both fed and drained by arterioles
The urinary system specifically the ___ maintain the ___ and ____ and other ___
Kidneys, purity, chemical constancy of blood, extra cellular body fluids
Each ureter begins at a level
L2, as a continuation of the renal pelvis
Branching extensions of the renal pelvis form 2 or three __
Major calices
Males
The urethra is about 8 inches and has 3 named regions
The length and the functions of the uretha differ in two sexes: females
The urethra is just 1.5 inches longmand isbound to the anterior wall of the vagina by c..t
2. Muscular layer
Thick detrusor muscle, consists of smooth muscle fibers arranged in inner and outer longitudinal layers and a middle circular layer
1. Paired ureters
Tube like structure that transports urine from the kidneys to the bladder - first structure transporting urine to bladder
What structure expels urine
Urethra
Ureters actively propel ___ to the ___ via response to ____
Urine, bladder, smooth muscle stretch
The kidneys also regulate the ___ and ___ of the blood
Volume and chemical makeup
2. External urethral sphincter
Voluntary sphincter surrounding the urethra as it passes through the urogenital diaphragm
3. Levator Ani muscle
Voluntary urethral sphincter
The pyramids apex points
Internally
The right kidney- location
Is crowded by he liver and lies slightly inferior to the left kidney
Bowmans capsule- outer layer
Is impermeable to contain the plasma that has been extracted
2. Loop of Henle
Is the portion of the nephron that leads for the proximal convoluted tubule to the distal convoluted tubule - the loop has a hairpin bend in the renal medulla
What is involved in the production of concentration of urine
Juxtmedullary nephrons
Renal sinus
Large filled space within the medial part of the kidney opening to the exterior through the renal hilus - sinus will be filled with urine
The urinary system- ureters
Left and right are muscular ducts that propel urine from the kidneys to the urinary bladder
Kidneys- location
Lie retroperitoneal (behind the parietal peritoneum) in the superior lumbar region of the posterior abdominal wall
Urinary bladder- location
Lies Retroperitoneally on the pelvic floor to the pubic symphysis
3. Pararenal fat
Lies external and mostly posterior to the renal fascia
The kidneys filter many ___ of fluid from the blood
Liters
Cone shaped masses in the medulla
Medullary pyramids or renal pyramids
Who has a longer urethra men or women?
Men
Each calices dived to form several ___
Minor calices
Nephron to
Minor calyx ( end of every pyramid) Major calyx Renal pelvis Ureter Bladder Urethra To Outside of body
2. Reabsorption
Most of the nutrients, water, and essential ions are recovered from the filtrate and returned to the blood of the capillaries in e surrounding connective tissue
Does blood ever leave the capillaries
No
Collecting duct system- at the apex of the pyramid adjacent collecting tubules join to form larger ___ which empty into the ___
Papillary ducts, minor calices
Urinary bladder- males
Prostate gland surrounds the neck inferiorly
Urinary bladder
Provides a temporary storage reservoir for urine - stores urine until full - second structure
What is confined entirely to the renal cortex
Proximal tubule
Peritubular capillaries- function
Reabsorbs some if the nutrients and plasma that were extracted in the Bowmans capsule
Loop of Henle- main function
Reabsorbs water and ions from the urine
4. Collecting duct system
Receive urine from several nephrons and runs straight through the cortex into the deep medulla
The afferent arterioles branch from the __ and feed the ___
Renal artery, glomerular capillaries
What separates the renal pyramids
Renal column
Ureters descends _____ through the ___ and enters the ___ through the ____
Retroperitoneally, abdomen, bladder, posterior wall
The uriniferous tubule is lined with
Simple epithelium
Urinary bladder
Smooth, collapsible, muscular sac that temporarily stores urine (up to 1 liter)
The glomerulus is contained within
The Bowmans capsule (glomerular capsule)
Efferent arterioles
The arteriole that carries the concentrated blood ( more cells, less plasma) away from the glomerulus and to the peritubular capillaries - smaller in diameter compared to the afferent arterioles
Renal corpuscle
The first part of the nephron, occurs strictly in the cortex
Capsular space
The glomerular endothelium is fenestrated allowing large quantities of fluid and small molecules to pass from the capillary blood into the hollow interior of the glomerular capsule- capsular space
The kidneys extend from
The level of the 11th/ 12th thoracic vertebrae to he 3rd lumbar vertebrae
Glomerulus
The minute convoluted capillary network in between the afferent arteriole and the efferent arteriole
Peritubular capillaries
The network of low pressure and porous capillaries that surround lie in the interstitial c.t. Of the renal cortex, clinging closely to the convoluted tubules and empty into nearby venules
What helps hold the kidney in place
The perirenal fat layers
3. Secretion
The remaining wastes contribute to the urine that leaves the body
The renal sinus contains
The renal vessels and nerves, some fat and the urine carrying tubes called renal calices and renal pelvis
1. Cortex
The superficial cortex region is light in color and had a granular appearance
The purpose of the renal corpuscle
To extract the renal filtrate (it is not yet to be called urine) from blood
The kidneys send _______ in urine while returning the needed substances back to the ___
Toxins, metabolic wastes, excess water, and excess ions, Back to the blood
1. Mucosa
Transitional epithelium and a lamina propria
Trigone
Triangular region on the posterior wall outlined by the openings of the ureters and the urethra
Urethra
Tube like structure that transports urine from the bladder out of the body - last structure
Renal columns
(Between renal pyramids) - inward extensions of the renal cortex, separate adjacent pyramids
1. Internal urethral sphincter
Involuntary sphincter at the bladder urethral junction
Internal gross anatomy- frontal section shows 2 distinct regions of kidney tissue
1. Cortex 2. Medulla
Three types of Sphincters in the urethra
1. Internal urethral sphincter 2. External urethral sphincter 3. Levant Ani muscle
3 regions of male urethra
1. Prostatic urethra - 2.5 cm long and runs in the prostate gland 2. Membranous urethra - 2.5 cm long and run through the urogenital diaphragm 3. Spongy (penile) urethra - 15 cm long, passes through the entire penis and opens at the tip of the penis via external urethral orifice
Collecting duct system- concentrates urine
Adh hormone increases permeability of the collecting tubules and distal tubules to water
What capsule consists of perirenal fat and external to it consists of renal fascia
Adipose capsule
What is larger in diameter? Afferent or efferent arterioles
Afferent arterioles
Bowmans capsule (aka glomerular capsule)
An expanded end of the renal tubule - it's contains glomerulus (capillary network)
Urinary bladder- female
Anterior to the vagina and uterus
Afferent arterioles
Are a group of blood vessels that supply the nephrons in many excretory systems
Microscopic anatomy of the kidneys- uriniferous tubules
Are the main structural and functional unit of the kidney.
2. Medulla
Deep to the cortex is the darker renal medulla, which consists of cone-shaped masses called medullary pyramids or renal pyramids
What is confined to the renal cortex
Distal convoluted tubule
The bladder is ___ and ___ when empty
Distensible, collapses
Urethra has a ____ function
Excretory. In both sexes to pass urine outside, and also reproductive function in the male as a passage for semen
As urine accumulates the bladder ____ without significant rise to ___
Expands, internal pressure
Female/male: the urethra opens to the outside at the
External urethral orifice
3. Adventitia
External wall made up of a typical c.t.
3. Adventitia
Fibrous c..t
Renal corpuscle consists of capillaries called
Glomerulus plus a glomerular capsule (Bowmans capsule)
Vasa recta
Hairpin looping vessels that descend into the medulla, running alongside the loops of Henle
How is the urethra a reproductive function
In males, it is a passageway for semen (not women)
What is deep to the cortex
Medulla
___ keep the urethra closed when urine is not being passed
Sphincters
Miturition is controlled by
The Brain. Distant ion of the bladder walls stimulate stretch receptors that initiate spinal reflexes at the sacral region that stimulate contraction of the external urethral sphincter and inhibit the detrusor muscle and internal sphincter (temporarily)
Micturition is caused by
The contraction of the bladders detrusor muscle, assisted by the muscles of the abdominal wall
Nephrons are divided into 2 categories according to it's location
1. Cortical nephrons 2. Juxtamedullary nephrons
Uriniferous tubules produce urine through 3 interacting mechanisms
1. Filtration 2. Reabsorption 3. Secretion
Three basic layers of the ureters
1. Mucosa 2. Muscularis 3. Adventitia
Uriniferous tubules are composed of
1. Nephron 2. Collecting duct
3 other parts of the urinary system
1. Paired ureters 2. Urinary bladder 3. Urethra
Renal tubule- comprised of
1. Proximal convoluted tubule 2. Loop of Henle 3. Distal convoluted tubule 4. Collecting tubule
External gross anatomy- What are the several layers of supportive tissue that surround each kidney
1. Renal capsule 2. Adipose capsule 3. Pararenal fat - layers protecting kidneys, keeping kidneys safe
3 main waste products
1. Urea 2. Uric acid 3. Creatine (Trying to get rid of mainly)
The wall of the bladder has 3 layers
1.mucosa 2. Muscular layer 3. Adventitia
2. Juxtmedullary nephrons
15% are located at the cortex- medulla junction, have loops of Henle that deeply invade the medulla, have extensive thin segments, are involved in the production of concentration of urine
The kidney has ___ lobes
5-11 lobes Each of which is a single renal pyramid plus the cortical tissue that surrounds that pyramid
1. Cortical nephrons
85% of nephrons, located in the cortex (except for a small part of the loop of Henle that dip into the medulla)
1. Filtration
A filtrate of the blood leaves the kidney capillaries and enters the nephron
Renal pelvis
A flat funnel shaped expansion of the ureter
1. Renal capsule
A thin layer of dense c.t. Adheres directly to the kidneys surface.. Maintaining it's shape and forming a barrier that can inhibit the spread of infection from the surrounding regions
