The Urinary System15 Flashcards
Kidneys dispose of waste products like
Nitrogenous wastes
Toxins
Drugs
Excess ions
Regulatory functions of kidneys
- Make renin to maintain blood pressure
- Make erythropoietin to stimulate RBC production
- Activate vitamin D
Organs in urinary systems
Kidneys
Ureters
Urinary bladder
Urethra
Which kidney is slightly lower?
Right
It’s because the liver sits in that space
Ureters
Carry urine to bladder for storage
Kidneys are at level of which vertabrae?
T12-L3
_____ are against dorsal body wall in retroperitoneal position (behind parietal peritoneum)
Kidneys
Length and width of adult kidney
12 cm long (5 in)
6 cm wide (2.5 in)
Renal hilum
Indentation where several structures enter and leave kidneys
____ gland sits atop each kidney
Adrenal
Layers of the kidneys
- Fibrous capsule
- Perirenal fat capsule
- Renal Fascia
Fibrous capsule of kidney
Encloses each kidney
Perirenal fat capsule
Surrounds kidney, cushions against blows
Renal Fascia
Most superficial layer
Anchors kidney and adrenal gland to surrounding structures
Renal cortex
Outer region
Between capsule and medulla
Renal medulla
Deeper regions
Renal/medullary pyramids
Triangular regions of tissue in the medulla
Renal columns
Extensions of cortex-like materials that separate the pyramids
Renal pelvis
Flat, funnel-shaped tube
Medial region
Calcyces function
Collect urine
Send to renal pelvis then ureters then bladder
Form cup shaped drains that enclose renal pyramids
Calcyces
Made by calyces joining together
Renal pelvis
One quarter of total blood supply passes through kidneys each ____
Minute
Provides kidney with arterial blood supply
Renal artery
Division of renal artery
1.Renal artery
2. Segmental arteries
3. Interlobar arteries
4.arcuate arteries
5. Cortical radiate arteries
Venous blood flow
1.Cortical radiate veins
2.arcruate veins
3. Interlobar veins
4. Renal vein
There are no _____ veins in the kidneys
Segmental
Renal vein blood returns into
Inferior vena cava
Filtration happens at site of
Glomerulus (capillaries)
Structural and functional units of the kidneys
Nephron
How many nephrons in one kidney
Over 1 million
Nephron made of 2 main structures which are
Renal corpuscle
Renal tubule
Glomerulus housed in
Renal corpuscle
A knot of capillaries made of podocytes
Glomerulus
Podocytes
Make up inner (visceral) layer of glomerular capsule
Foot processes cling to
Glomerulus
____ slits make a porous membrane ideal for filtration
Filtration
Renal corpuscle parts
- Glomerulus
- Glomerular (Bowman’s) capsule
Glomerular Bowman’s capsule
Cup-shaped structure that surrounds glomerulus
First part of renal tube
Glomerular (Bowman’s) capsule
Renal tubule Extends from
glomerular capsule and ends when it empties into collecting duct
Subdivisions of renal tubule
1.Proximal convoluted tubule (PCT)
2.Nephron loop (loop of Henle)
3.distal covered tubule (DCT)
Proximal because it’s closest to the
Glomerulus
Cortical nephrons
Located entirely in cortex
Include most nephrons
Juxtamedullary nephrons found at
Found that the cortex-medulla junction
Juxtamedullary nephrons are called that because
Nephron loops dip deep into medulla
Collecting ducts collect urine from which types of nephrons?
Both cortical and juxtamedullary nephrons
Collecting ducts go through which structures
Renal pyramids
Calyces
Renal pelvis then ureters, then bladder
Two capillary beds associated with each nephron
Glomerulus
Peritubular capillary bed
Glomerulus is fed and drained by
Arterioles
Afferent arteriole
Arises from cortical radiate artery and feeds glomerulus
Efferent arteriole
Receives blood that has passed through glomerulus
How does the glomerulus work?
High pressure forces fluid and solutes out of blood and into glomerular capsule
Peritubular capillary beds arise from
Efferent arteriole of the glomerulus
Low-pressure porous capillaries
Peritubular capillary beds
Which capillary beds are adapted for absorption instead of filtration?
Peritubular capillary beds
Function of peritubular capillary beds
Cling close to renal tubule to receive solutes and water from tubule cells
Peritubular capillary beds drain into
Interlobar veins
Urine formation is a result of which 3 processes
Glomerular filtration
Tubular reabsorption
Tubular secretion
Glomerular filtration
Water and solutes forced through capillary walls and pores of glomerular capsule into renal tubule
Tubular reabsorption
Water, glucose, aminoacids and needed ions are transported into tubule cells and capillary blood
Tubular secretion
H,K, creatinine and drugs removed from peritubular blood and secreted by tubule cells into the filtrate
Is a filter
Glomerulus
Proteins and blood are too ____ to pass through the _____ membrane
Too large to pass through the filtration membrane
Once in glomerular capsule, fluid is called
Filtrate
Filtrate leaves via
Renal tubule
Filtrate will be formed as long as systemic blood pressure is
Normal
If arterial blood pressure is too low filtrate formation stops because
Glomerular pressure will be too low to form filtrate
Peritubular capillaries reabsorb useful substances from the renal tubule cells such as
Water
Glucose
Amino acids
Ions
Tubular reabsorption passive or active
Some is reabsorption is passive, most is active
Most reabsorption occurs in
Proximal convoluted tubule
Reabsorption in reverse
Tubular secretion
Some Materials move from the blood in peritubular capillaries into the renal tubules to be eliminated in filtrate
Tubular secretion
Which materials move back into the renal tubules during tubular secretion
Hydrogen and potassium ions
Creatinine
How many liters of urine are produced in 24 hours?
1.0 to 1.8
Differences between urine and filtrate
- Filtrate has everything blood plasma has except proteins
- Urine has nitrogenous wastes and not needed substances
What remains after the filtrate has lost most of its water, nutrients , and necessary ions through reabsorption
Urine
Urochrome
Makes urine yellow
Due to destruction of hemoglobin
Sterile at time of formation
Urine
Urine smell
Slightly aromatic, smells of ammonia with time
pH of urine
6
Specific gravity of urine
1.001 to 1.035
Solutes normally found in urine
1.Na & K ions
2.Urea, Uric acid and creatinine
3. Ammonia
4. Bicarbonate ions
Abnormal solutes in urine
1.Glucose
2.Blood proteins
3. RBCs
4.Hemoglobin
5.WBCs (pus)
6. Bile
Glucose in urine
Nonpathological : excessive intake of sugary foods
Pathological: diabetes mellitus
Proteinuria
Nonpathological: Physical exertion, pregnancy
Pathological: Glomerulonephritis, hypertension
Pyuria
Urinary tract infection
Hematuria
Bleeding in urinary tract due to trauma, kidney stones, infection
Hemoglobinuria
Transfusion reaction
Hemolytic anemia
Bilirubinuria
Liver disease (hepatitis)
Ureters size
Slender tubules
25-30 cm (10-12 inches)
What attaches kidneys to urinary bladder
Ureters
What is continuous with the renal pelvis?
Ureters
What enters the posterior aspect of the urinary bladder?
Ureters
What runs behind the peritoneum?
Ureters
Peristalsis aids gravity in ____ transport
Urine
Smooth, collapsible muscular sac situated posterior to pubic symphysis.
Urinary bladder
Stores urine temporarily
Trigone
Triangular region of urinary bladder base, based on 3 openings
Openings of trigone
Two openings from the ureters (ureteral orifices)
One opening to the urethra (internal urethral orifice)
____ surrounds the neck of urinary bladder
Prostate
Detrustor muscle
3 layers of smooth muscle in wall of urinary bladder
Mucosa of urinary bladder is made of
Transitional epithelium
Transitional epithelium lets urinary bladder do what?
Can expand significantly without raising internal pressure
What are the walls like in an empty urinary bladder?
Thick and folded
Size and capacity of moderately full bladder
5 inches
Holds around 500 ml
How much water can a full bladder hold?
1 L approximately
Thin walled tube that carries urine from bladder to the outside
Urethra
Function of urethra in men and women
In men, carries sperm and urine
In women, carries urine
Internal urethral sphincter
Involuntary and made of smooth muscle
External urethral sphincter
Voluntary and made of skeletal muscle
Sphincters that control urine release
Internal and external urethral sphincters
Length of female urethra
3-4 cm (1.5 inches)
Length of male urethra
20 cm (8 inches)
Location of urethra in women
Anterior to the vaginal opening
Location of urethra in males
Travels through prostate and penis
Parts of male urethra
Prostatic urethra
Membranous urethra
Spongy urethra
Micturition
Voiding or emptying of urinary bladder
Bladder collects urine to ____ Mls it then gets told to stretch
200
Stretch receptors transmit impulses to the ____ receptors of the spinal cord
sacral region of the spinal cord
Impulses travel to bladder via which nerves? To cause bladder contractions
Pelvic splanchnic nerves
What causes you to want to pee?
Stronger contractions, urine forced past involuntary internal sphincter.
What lets you resist the urge to pee?
The external sphincter because it’s voluntarily controlled
Blood composition depends on 3 factors
1.Diet
2. Cellular metabolism
3. Urine output
Kidneys have 4 roles maintaining blood composition
- Excreting nitrogen containing waste
- Maintaining water balance of blood
- Maintaining electrolyte balance of blood
- Ensuring proper blood pH
Normal amount of water in young adult females
50%
Normal amount of water in young adult males
60%
Normal amount of water in babies
75%
Normal amount of water in the elderly
45%
Water occupies 3 main fluid compartments
Intracellular fluid
Extracellular fluid
Plasma
ICF intracellular fluid
1.Fluid inside cells
2.Accounts for 2/3 of body fluid
ECF
Fluids outside cells
Blood plasma, interstitial fluid, lymph, transcellular fluid.
Plasma accounts for ___ L of total body water
3
Plasma
Links external and internal environments
Electrolyte examples
Na, K, Ca ions
Charged particles that conduct electrical current in aqueous solution
Electrolytes
Driving force for water intake
Thirst mechanism
Sources for water intake
Ingested foods and fluids
Water made from metabolic processes
To remain properly hydrated, water I and O must be
Equal
Amount of water produced by metabolic processes
10%
Osmoreceptors found in
Hypothalamus
Osmoreceptors
Become more active in reaction to small changes in plasma solute concentration
When the thirst mechanism is activated, the thirst center in the ____ is activated
Hypothalamus
A dry mouth can also promote the _____ mechanism
Thirst
Two things that activate thirst mechanism
Osmoreceptors in hypothalamus
Dry mouth
Sources of water output
Lungs (insensible since we can’t see water leaving)
Perspiration
Feces
Urine
ADH
Antidiuretic hormone
Prevents excessive water loss in the urine and increases water reabsorption
ADH targets which part of the kidneys?
Collecting ducts
What causes water to move from one fluid compartment to another?
Small changes in electrolyte concentration
Function of aldosterone
Regulate blood composition and blood volume by acting on kidney
For each sodium ion reabsorbed a chloride ion
Follows, and potassium is secreted into the filtrate
What happens when sodium is reabsorbed?
Water follows it passively into the blood
Water follows salt
Explain the renin-angiotensin mechanism
When cells from juxtaglomerular (JG) apparatus are stimulated by low blood pressure, enzyme renin is released into blood
What mediates the renin-angiotensin mechanism?
JG apparatus
What is the most important trigger for aldosterone release?
Renin-angiotensin mechanism
Renin
Catalyzes reactions that produce angiotensin II
Angiotensin II causes what?
Vasoconstriction and aldosterone release
What does the renin-angiotensin mechanism result in?
Increased blood volume and blood pressure
To maintain homeostasis, blood pH must stay between
7.35 and 7.45
Alkalosis pH
Above 7.45
Acidosis pH
Below 7.35
Physiological acidosis
pH between 7.0 and 7.35
What plays greatest role in maintaining acid-base balance of blood?
Kidneys
Other acid-base controlling systems
Blood buffers
Respiration
Carbonic acid is a ___ acid
Weak
Weak base examples
Bicarbonate ions and ammonia
What do molecules do when pH drops?
Bind to H+ ions
What do molecules do when pH rises?
Release H+
Three major chemical buffer systems
- Bicarbonate buffer system
- Phosphate buffer system
- Protein buffer system
Bicarbonate buffer system made of
Carbonic acid H2CO3
Bicarbonate NaHCO3
Explain the bicarbonate buffer system
1.Carbonic acid is weak,
Bicarbonate ions react with strong acids to make them weak acids
- Carbonic acid reacts with strong bases(NaOH) to form weak base and water
How does the respiratory mechanism regulate blood pH
Resp. Rate can rise or fall to increase or decrease amount of CO2 .
High breathing rate increases pH and decreases CO2
Renal mechanisms: what happens when blood pH rises ?
More basic
Bicarbonate ions excreted. H retained by kidney tubules
Renal mechanisms: when blood pH falls?
More acidic
Bicarbonate is reabsorbed. H is secreted
Urine pH range
4.5-8