Urinary System Flashcards
Describe the structures and location of the kidneys
Kidneys are bean shaped organs that filter blood, located on either side of the spine, below the rib cage, in the back of the abdominal cavity
What are the ureters and their function?
Ureters are narrow, muscular tubes that run from each kidney to the bladder, transporting urine
Describe the urinary bladder
A hollow, muscular organ shaped like a balloon, located in the pelvis behind the pubic bone, temporarily storing urine
Explain the role of the urethra in the urinary system
A muscular tube that extends from the bladder to the external urethral orifice, where urine exits the body
Lis the order of structures urine flows through to leave the body
kidneys–> ureters–> bladder–> urethra–>outside body
Define the major functions of the urinary system
kidneys- filtration, reabsorption and secretion
bladder- storage
ureters and urethra- transportation
How do the kidneys contribute to filtration in the urinary system?
The kidneys filter blood to remove waste products and excess substances forming urine
What is the role of the urinary bladder?
The urinary bladder temporarily stores urine until it is ready to be eliminated
Describe the renal cortex
The renal cortex is the outer region of the kidneys that contains all of the nephrons
What is the renal medulla?
The inner region of the kidneys that contains renal pyramids
Explain the structure and function of renal pyramids
cone shaped tissues in the medulla containing collecting ducts and the loops of henle of juxtamedullary nephrons
What are renal columns?
Extensions of the renal cortex into the renal medulla, containing blood vessels and connective tissues, separating pyramids and papillae
Describe the renal hilum
The entry and exit site for blood vessels, nerves, lymphatics, and the ureters
List the structures a drop of blood flows through starting from the renal artery
renal artery–> segmental artery–> interobar artery–> arcuate artery–> cortical radiate artery–> affe3rent arteriole–> glomerulus–> efferent arteriole–> peritubular capillaries–> cortical radiate vein–> arcuate vein–> interobar vein–> renal vein
What is the difference between blood in the renal artery and renal vein?
Blood in the renal artery contains more waste products and less oxygen compared to blood in the renal vein, which has been filtered and has lower waste levels
Describe the nutrient and wast content in the renal artery and renal vein
The renal artery contains a higher concentration of waste products, while the renal vein has lower waste content since it has been filtered by the kidneys
Explain the electrolyte balance in the renal artery compared to the renal vein
The renal artery may have a different balance of electrolytes that are carried to the kidneys for regulation, whereas the renal vein typically has a well balanced composition of electrolytes
How does the pH differ between the renal artery and renal vein?
The pH in the renal artery can vary more widely depending on the body’s condition, while the renal vein typically has a stable pH since the kidneys regulate acid base balance
Define the structures that create a nephron and their major functions
The nephron consists of the glomerulus and Bowman’s capsule (initial filtration), proximal convoluted tubule (majority of nutrient reabsorption), nephron loop (water and ion reabsorption), distal convoluted tubule (electrolyte adjustment and pH balance), and collecting duct (final urine concentration)
Describe the role of the glomerulus in the nephron
The glomerulus is a network of capillaries where blood pressure forces water and solutes out of the blood into the Bowman’s capsule, initiating urine formation
How does the proximal convoluted tubule (PCT) function in the nephron?
Responsible for the reabsorption of the majority of nutrients
Explain the function of the nephron as a whole
The nephron cleanses the blood and balances the constituents of the circulation
Describe the difference between cortical nephrons and juxtamedullary nephrons
Cortical nephrons have a short loop of Henle that does not dip beyond the cortex, while juxtamedullary nephrons extend deep into the medulla
How do the ureters move urine toward the bladder?
Through waves of peristalsis into the bladder
State the tissue type in the ureter that facilitates the movement of urine
The lumen of the ureters is lined with transitional epithelium, and the outer muscular layer is made of 2 layers of smooth muscles that create peristaltic contraction
What is the range of volume of an adult bladder?
The volume in adults can range from nearly 0 to 500-600mL
Identify the tissue type that allows the bladder to accommodate varying volumes
The bladder is made of transitional epithelium, which allows it to stretch and accommodate varying volumes
Describe the lining of the bladder and how it changes when full
The bladder is lined with transitional epithelium, which appears columnar when empty and transitions to a more squamous appearance when full.
Define the detrusor muscle and its role in the bladder
The detrusor muscle is made of irregular crisscrossing bands of smooth muscle that contract to facilitate the expulsion of urine from the bladder
Explain the function of the urethra
The urethra transports urine from the bladder to the outside of the body for disposal
Describe the internal urinary sphincter and its characteristics
The internal urinary sphincter is located at the opening into the urethra from the urinary bladder and is made of smooth muscle regulated by the involuntary autonomic nervous system
Describe the external urinary sphincter and its characteristics
The external urinary sphincter is located inferior to the internal urinary sphincter and is made of voluntary skeletal muscle
Outline the steps involved in micturition (urination)
- urinary bladder fills and activates stretch receptors
- stretch receptors send signals to the sacral region of the spinal cord
- the spinal cord triggers the micturition reflex, causing contraction of the detrusor muscle and relaxation of the internal urethral sphincter
- the external urethral sphincter relaxes due to inhibition of somatic motor neurons
- urine is expelled from the body
Identify the structure that allows control over micturition timing
The external urethral sphincter allows for the delay of micturition, which is learned during potty training
Define glomerular filtration and its significance in urine production
glomerular filtration is the first step in urine production where water and solutes in the blood plasma move across the walls of the glomerular capillaries into the renal tubules
Explain tubular reabsorption and its importance
Tubular reabsorption occurs throughout the nephron tubules to the collecting ducts, returning water and solutes to the blood to prevent loss of water, nutrients, and essential ions
Describe tubular secretion and its role in the body
Tubular secretion occurs throughout the nephron tubules to the collecting ducts, removing excess substances and wastes from the blood and helping to regulate blood pH and electrolyte balance
What is urinary excretion and its purpose?
Urinary excretion removes waste products and excess substances from the bloodstream, maintaining the body’s chemical balance and fluid levels
Describe a renal corpuscle and its components
A renal corpuscle consists of the glomerulus and Bowman’s capsule, functioning together in the filtration of blood
Describe the function of the glomerular capillaries
The glomerular capillaries filter blood based on particle size
Explain the structures of the juxtaglomerular apparatus
The juxtaglomerular apparatus consists of the macula dense and juxtaglomerular cells, located just outside of Bowman’s capsule
What role does the macula dense play in kidney function?
The macula dense monitors the flow rate and sodium ion concentration of the filtrate in the distal convoluted tubule
Define juxtaglomerular cells
Juxtaglomerular cells are modified smooth muscle cells of the afferent arteriole that secrete renin in response to a drop in blood pressure
Define blood hydrostatic pressure
Blood hydrostatic pressure is the pressure of blood within capillaries that pushes fluid out into surrounding tissue
What is blood colloid osmotic pressure?
Blood colloid osmotic pressure, also known as oncotic pressure, is the force exerted by plasma proteins in the blood that helps maintain fluid balance
Explain capsular hydrostatic pressure
Capsular hydrostatic pressure is the pressure exerted by fluid in Bowman’s capsule against the filtration membrane in the kidneys
Define net filtration pressure
Net filtration pressure is the sum of hydrostatic and osmotic pressures that drive fluid out of capillaries
How is glomerular filtration rate (GFR) defined?
Glomerular filtration rate is the amount of filtrate formed in all renal corpuscles of both kidneys each minute
Describe the process of blood filtration in the kidneys
Blood enters the kidneys, is cleaned in the glomeruli, where waste products and extra fluids are filtered out to form urine, while blood cells and proteins remain in the bloodstream
Explain the myogenic mechanism of auto regulation of GFR
The myogenic mechanism regulates blood flow through the kidney by causing smooth muscle cells of the afferent arteriole to contract when stretched due to increased blood pressure, and relax when blood pressure decreases
How does the myogenic mechanism affect GFR during increased blood pressure?
During increased blood pressure, the smooth muscle cells of the afferent arteriole contract, causing vasoconstriction, which minimizes changes in blood flow and GFR
What happens to GFR when blood pressure decreases?
When blood pressure decreases, the afferent arteriole muscle cells relax, causing vasodilation, which maintains blood flow and minimizes changes in GFR
Explain tubuloglomerular feedback
Tubuloglomerular feedback is a mechanism that regulates kidney function by having the macula dense detect changes in sodium ion concentration and secrete signals that control the contraction and relaxation of juxtaglomerular cells
What occurs when filtrate osmolarity is high?
When filtrate osmolarity is high, juxtaglomerular cells contract, reducing GFR, decreasing urine formation, and retaining fluid to lower blood osmolarity
Describe the response of juxtaglomerular cells when osmolarity is low
When osmolarity is low, juxtaglomerular cells relax, increasing GFR and urine formation, which raises blood osmolarity
What is the countercurrent multiplier?
The countercurrent multiplier is a mechanism in the kidneys that helps concentrate urine and maintain osmotic gradients
Describe the function of the loop of Henle in the kidney
The loop of Henle concentrates urine and balances water and salts through fluid movement in opposite direction
Explain the fluid flow in the loop of Henle
Fluid moves down the descending limb and up the ascending limb
How does water movement occur in the descending limb of the loop of Henle?
Water moves out due to high salt concentration outside, making the fluid inside more concentrated
What happens in the ascending limb of the loop of Henle?
Salt is pumped out without water following, which reduces the fluid’s concentration
Define the role of urea in the kidney
Urea helps concentrate the kidney’s surrounding fluid, enhancing water reabsorption in later parts of the kidney
How does the kidney conserve water?
By concentrating urine effectively through the processes in the loop of Henle and the action of hormones
Describe the function of angiotensin II in the kidney
Angiotensis II is a vasoconstrictor that narrows the afferent and efferent arterioles, reducing blood flow and decreasing GFR
What effect does atrial natriuretic peptide have on GFR?
It causes relaxation of the glomerular cells and increases GFR by increasing the surface area
Explain the role of antidiuretic hormone (ADH) in urine concentration
ADH regulates the amount of water reabsorbed at the collecting ducts, concentrating urine by increasing aquaporin channels
How does aldosterone affect sodium and potassium levels in the kidney?
Aldosterone increases Na+ reabsorption and causes greater loss of K+ in response to angiostensin II stimulation
Describe the relationship between ADH and urine concentration
High ADH levels lead to concentrated urine due to more aquaporins and greater water reabsorption
How does the urinary system control blood pH?
It secretes H+ and reabsorbs bicarbonate, adjusting blood pH
Explain the difference between dilute and concentrated urine production
Dilute urine is produced with los ADH and fewer aquaporin channels, while concentrated urine is produced with high ADH and more aquaporins
What is the effect of low ADH on urine production?
Low ADH results in fewer aquaporin channels and less water reabsorbed, leading to dilute urine
What occurs when ADH levels are high in the body?
High ADH levels increase the number of aquaporin channels, leading to greater water reabsorption and concentrated urine
