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