BSCI202- Exam #3

Kidneys, ureters, urinary bladder, and urethra

What are the urinary system organs?

A smooth, collapsible, muscular sac

What is the urinary bladder?

Temporarily stores urine

What is the main function of the urinary bladder?

About 5 inches

How long is the bladder when full?

About 500ml

How much urine can a full bladder normally hold?

Two times

How much more can the bladder hold beyond its normal capacity?

Trigone

A triangular area of the urinary bladder with three openings.

Three openings

How many openings are in the trigone?

Two openings from the ureters and one opening to the urethra

What are the three openings of the trigone?

Detrusor muscle

Three layers of smooth muscle in the bladder wall.

Smooth muscle

What type of muscle makes up the detrusor?

Transitional epithelium

What is the mucosa in the urinary bladder wall made of?

Thick and folded

What do the bladder walls look like when the bladder is empty?

To allow the bladder to expand as it fills with urine

Why are the bladder walls folded when empty?

It expands and its folds stretch out

What happens to the bladder as it fills with urine?

Its walls stretch and unfold as it fills

How can the bladder hold more liquid without increasing internal pressure?

Internal and external

What are the two urethral sphincters?

Involuntary

Is the internal urethral sphincter voluntary or involuntary?

At the bladder-urethra junction

Where is the internal urethral sphincter located?

Voluntary

Is the external urethral sphincter voluntary or involuntary?

The urethra

What does the external urethral sphincter surround?

Internal urethral sphincter

Which sphincter controls urination involuntarily?

External urethral sphincter

Which sphincter allows voluntary control of urination?

Female is 3cm and male is 20cm

How big the urethra for a female vs a male?

The male urethra carries urine and semen and the female urethra carries just urine

What are the two functions of the male urethra and the one function of the female urethra?

Clean blood and get rid of waste products

What is the function of the kidneys?

The right kidney is slightly lower than the left

Which kidney is slightly lower than the other?

Because the large liver sits above it and pushes it downward

Why is the right kidney slightly lower than the left?

Renal hilum

A medial indentation (opening) in the kidney.

The ureter, renal blood vessels, and nerves

What passes through the renal hilum?

Adrenal gland

What gland is located on top of each kidney?

About 1/4 cardiac output

How much of the cardiac output passes through the kidneys each minute?

1200ml

How much blood flows through the kidneys each minute?

Renal artery

What carries blood TO the kidneys?

Renal vein

What carries blood AWAY from the kidneys?

Renal cortex and renal medulla

What are the two main regions of the kidney?

Renal cortex

The outer region of the kidney.

Renal medulla

The inner region of the kidney.

Renal columns

Extensions of the renal cortex that extend between the renal pyramids.

Renal pyramids

Cone-shaped structures located in the renal medulla.

Renal papilla

The tip of a renal pyramid.

Releases urine into the minor calyx

What does the renal papilla do?

Into the minor calyx

Where does urine go after leaving the renal papilla?

Renal pelvis

A funnel-shaped structure that collects urine.

The ureter

What is the renal pelvis continuous with?

Collects urine and funnels it into the ureter

What is the function of the renal pelvis?

Nephrons

Structural and functional units of kidney.

> 1 million per kidney

How many nephrons per kidney?

Renal corpuscle and renal tubule

What are the two parts of a nephron?

Glomerulus and glomerular capsule

What are the two parts of the renal corpuscle?

Glomerulus

Knot of capillaries within a glomerular (Bowman’s) capsule.

Collects the fluid filtered from the glomerulus

What is the function of the glomerular capsule?

Proximal convoluted tubule, nephron loop, and distal convoluted tubule

What are the three parts of the renal tubule?

Cortical and juxtamedullary nephrons

What are the two types of nephrons?

Cortical nephrons

Located in the cortex; most nephrons.

Juxtamedullary nephrons

Boundary of the cortex; dip deep into the medulla.

Various capillary beds

What are nephrons associated with?

Glomerulus, peritubular capillary bed, and vasa recta

What are the three capillary beds associated with nephrons?

Peritubular capillary bed

A network of capillaries surrounding the renal tubules.

Vasa recta

Straight capillaries associated with the nephron loops of juxtamedullary nephrons.

Juxtamedullary nephrons only

Which type of nephron has the vasa recta?

The nephron loop

Which nephron structure is associated with the vasa recta?

Podocytes

Specialized cells that wrap around glomerular capillaries and help form the filtration barrier.

Afferent arteriole

What blood vessel brings blood INTO the glomerulus?

Efferent arteriole

What blood vessel carries blood AWAY from the glomerulus?

A cortical radiate artery

Where does the afferent arteriole come from?

High pressure pushes fluid and small solutes into the glomerular capsule

Why is pressure important in the glomerulus?

Filtrate

What is the filtered fluid called?

Glomerular filtration rate

The amount of fluid filtered by the kidneys per minute.

Approximately 125 mL/min

What is the normal GFR?

Approximately 180 liters per day

How much filtrate is produced per day?

High blood pressure within the glomerular capillaries

What causes filtration in the glomerulus?

Tubular reabsorption

The movement of substances from the renal tubules back into the blood.

Into the peritubular capillaries

Where do reabsorbed substances go?

The efferent arteriole of the glomerulus

Where do peritubular capillaries come from?

They cling closely to and surround the renal tubules

Where are peritubular capillaries located?

Reabsorb substances from the renal tubules back into the bloodstream

What is the function of peritubular capillaries?

From the tubules → into the peritubular capillaries → back into the blood

What is the direction of tubular reabsorption?

Useful

The peritubular capillaries reabsorb _____ substances.

Water, glucose, amino acids, and ions

What useful substances do the peritubular capillaries reabsorb?

Proximal convoluted tubule

Where does most tubular reabsorption occur?

Some is passive, but most is active

Is tubular reabsorption passive or active?

Passive reabsorption

Movement of substances without using cellular energy (ATP).

Active reabsorption

Movement of substances that requires cellular energy (ATP).

Because they are useful substances the body needs

Why does the body reabsorb glucose and amino acids?

To return useful substances from the filtrate back into the bloodstream

What is the main purpose of tubular reabsorption?

Tubular secretion

Movement of materials from the peritubular capillaries into the renal tubules.

Potassium, hydrogen ions, choline, creatinine, and penicillin

What are some of the substances secreted during tubular secretion?

They move toward the ureter

Where do materials left in the renal tubule go?

Collecting duct

What receives urine from many nephrons?

The medullary pyramids

Where do collecting ducts run through?

Into the calyces and renal pelvis

Where do collecting ducts deliver urine?

Glomerular filtration, reabsorption, secretion, and excretion

What are the four basic renal processes?

Glomerular filtration

Movement of fluid and small solutes from the glomerulus into the glomerular capsule.

Tubular reabsorption

Movement of useful substances from the tubules into the peritubular capillaries.

Tubular secretion

Movement of substances from the peritubular capillaries into the renal tubules.

Excretion

The removal of urine and waste from the body.

Amount of substance excreted = amount filtered + amount secreted – amount reabsorbed

What is the formula for excretion rate?

1 to 1.8 liters

How many liters of urine are produced in 24 hours?

95% water and 5% solutes

What percent of water and solutes is urine?