UMich NURS 210/211: Chapter 25

Urinary system consists of

kidneys, ureters, urinary bladder, urethra

The urinary

Maintains homeostasis by managing the volume and composition of fluid reservoirs, primarily blood

What are the kidney's function?

- Regulation of blood ionic composition (Na+, K+, Cl-)

- Regulation of blood pH (H+, HCO3-)

- Regulation of blood volume (H2O)

- Regulation of blood pressure

- Maintenance of blood osmolarity

- Production oh hormones

- Excretion of metabolic wastes and foreign substances

- Regulation of blood glucose level

Kidneys are ____________, partially protected by the lower ribs

Retroperitoneal

The indented area of the kidney is the

Renal hilum

The renal hilum is the entrance for:

renal artery, renal vein, ureter, nerves, lymphatics

External layers of the kidney is made of

Connective tissue

The external layers of the kidney are

Renal fascia, adipose capsule, and renal capsule

The renal fascia does what

anchors the kidney to surrounding structures

The adipose capsule does what?

Protects and anchors

The renal capsule does what?

Continuous with ureter

The internal renal anatomy of the kidneys are:

Renal cortex, renal medulla, renal pyramids, renal columns

What is the renal cortex?

outer layer of the kidney

What is the renal medulla?

inner portion of the kidney

What is the renal pyramids?

secreting apparatus and tubules

What is the renal columns?

Anchor the cortex

What is the blood supply of the kidneys like?

Although kidneys constitute less than 0.5% of total body mass, they receive 20-25% of resting cardiac output

What is the nerve supply like for the kidneys?

The renal nerved primarily carry sympathetic outflow. They regulate blood flow through the kidneys.

What is the functional unit of the kidney?

nephron (a tiny funnel with a long winding stem)

How many nephrons are in each kidney?

Over a million

How much blood is filtered through the nephron?

45 gallons of blood each day.

The renal corpuscle consists of two parts:

1. Glomerular (Bowman's) Capsule

2. Glomerulus

The glomerulus is a

Mass of capillaries that is fed by the afferent arteriole and drains into the efferent arteriole

The glomerulus (Bowman's) capsule has

A visceral layer of podocytes, which wrap around the capillaries

In the glomerular capsule filtrate is

Collected between the visceral and parietal layers

The glomerular endothelial cells have

Large pores and are leaky

Basal laminate lies between

endothelium and podocytes

Podocytes form pedicels

between which are filtration slits

What percent of nephrons are cortical nephrons?

80-85%

Where are cortical nephrons located?

Outer cortex and loop of henle

Cortical nephrons do what?

Create urine with osmolarity similar to blood.

What percent of nephrons are juxtamedullary nephrons?

15%

What do juxtamedullary nephrons do?

Enable kidney to secrete very concentrated urine

The release of renin activates

The angiotensin mechanism which increases BP body-wide

The nephron increases the surface area for

Urine processing and allows time for the different stages of urine production

What are the three stages of urine production?

filtration, reabsorption, secretion

The excretion of urine is

Glomerular filtration + secretion - reabsorption

Glomerular filtration is driven by

Blood pressure

Glomerular filtration is opposed by

capsular hydrostatic pressure and blood colloid osmotic pressure

What moves out of the glomerulus?

water and small molecules

How many liters of water pass out into the glomerular capsule?

150-180 liters

What is the glomerular filtration rate (GFR)?

the amount of filtrate the kidneys produce each minute

Homeostasis requires kidneys to

maintain a relatively constant GFR

What happens if the GFR is too high?

substances pass too quickly and are not reabsorbed

What happens if the GFR is too low?

nearly all reabsorbed and some waste products not adequately excreted

GFR is controlled by

renal autoregulation, neural regulation, hormonal regulation

In tubular reabsorption much of the filtrate

Is reabsorbed, especially water, glucose, amino acids, and ions

In tubular secretion helps to manage

pH and rid the body of toxic and foreign substances

Primary Active Transport uses

ATP, like Na+/K+ pumps

At rest, Primary active Transport accounts for

6% total body ATP use

Secondary active transport is driven by

an ion's electrochemical gradient

In secondary active transport, what moves substances what ways?

Symporters move substances in same direction

Anti porters move substances in opposite directions

What percent is obligatory water reabsorption?

90%

In obligatory water reabsorption, water follows

The solutes that are reabsorbed

What percent is facultative water reabsorption?

10%

Facultative water reabsorption is regulated by

ADH

In the loop of Henle, the descending limb

Continues water reabsorption

In the loop of Henle, the ascending limb

Solute reabsorption only

Symporters in the PCT Transport Mechanisms are

Na+ —glucose

Antiporters in the PCT Transport Mechanisms are

Na+ —H+

The loop of henle is relatively

Impermeable to water, especially the ascending limb

The loop of henle has little

Obligatory water reabsorption

The transfer of ions in the loop of henle is

Na+ —K+—2CL- symporters

_____ symporters reabsorb ions.

Na+—Cl-

____ stimulates reabsorption of Ca2-.

PTH

PTH also inhibits phosphate reabsorption in the

PCT, enhancing its excretion

____ pumps reabsorb Na+

Na+—K+

Water reabsorption is stimulated by

ADH

In urine production, fluid intake

Is highly variable

In urine production, homeostasis requires maintenance of

Fluid volumes within specific limits

Urine concentration varies with

ADH

High intake of fluid results in

dilute urine of high volume

Low intake of sluid results in

Concentrated urine of low volume

What is the osmolarity of Glomerular filtrate and blood?

300mOsm/Liter

Tubular osmolarity changes due to

a concentration gradient in the medulla

When dilute urine is formed, osmolarity in the tubule

1. Increases in the descending limb

2. Decreases in the ascending limb

3. Decreases more in the collecting duct

In thick ascending limb, symporters actively absorb

Na+, K+, Cl-

In thick ascending limb, the water permeability is ____

Low

In the thick ascending lib, solutes ____ and water _____

solutes leave and water stays in tubule

In the collecting duct, there is a

Low water permeability in absence of ADH

What is the path for renal function?

1. Glomerulus

2. Proximal Convoluted Tubule (PCT)

3. PCT and descending limb

4. Thick ascending limb

5. DCT and collecting ducts

6. Urine Production

Anti-diuretic hormone is released by the

posterior pituitary

normal urine composition

95% water, nitrogenous waste, electrolytes, toxins, pigments, hormones

Nitrogen wastes include

Urea (most abundant), Uris acid, creatinine

Electrolytes include

H+ ions, sodium, potassium, calcium

Pigments include

Urochromes from RBC breakdown

Routine urinalysis primarily evaluates for the presence of ___ in the urine; which include?

abnormalities; albumin, glucose, RBC, ketone bodies, microbes

Each ureter transports urine from a renal pelvis by

peristaltic waves, hydrostatic pressure, and gravity

There is no anatomical valve at

The opening of the ureter into bladder

The bladder is a

Hollow, distensible, muscular organ with a capacity averaging 700-800 mL