Renal System Lecture Review

These flashcards cover the gross anatomy, functions, nephron structure, filtration dynamics, pressure regulation, and cellular transport mechanisms discussed in the renal system lecture.

Which organs make up the gross anatomy of the renal (urinary) system?

Two kidneys, two ureters, one urinary bladder, and one urethra

Where are the kidneys located in the body?

In the retroperitoneal space

What are the two simplified overall functions of the renal system?

Filtering blood plasma and regulating blood osmolarity

During filtration, what components of blood are NOT filtered into the nephron?

Blood cells and most plasma proteins

How is blood osmolarity related to blood pressure and blood volume?

Solute concentration (osmolarity) helps draw water into blood; more water increases volume and therefore pressure

What is the functional unit of the kidney?

The nephron

Approximately how many nephrons are in each kidney?

About one million

Name the two major regions of the kidney visible in frontal section.

Renal cortex (outer) and renal medulla (inner)

Where are most nephron structures located?

Primarily in the renal cortex, with some parts (loop of Henle, collecting ducts) dipping into the medulla

List the main segments of a nephron in order of filtrate flow.

Bowman's capsule → Proximal convoluted tubule → Loop of Henle → Distal convoluted tubule → Collecting duct

What two structures together are called the renal corpuscle?

Bowman's capsule and the glomerulus

What is the glomerulus?

A tuft (bed) of capillaries inside Bowman's capsule where filtration occurs

Which arteriole brings blood INTO the glomerulus?

The afferent arteriole

Which arteriole carries blood AWAY from the glomerulus?

The efferent arteriole

What unusual vascular arrangement exists in the kidney and what is it called?

An arteriole–capillary–arteriole sequence forming a portal system

What capillary network arises from the efferent arteriole and surrounds nephron tubules?

The peritubular capillary

Define glomerular filtration rate (GFR).

The rate at which plasma is filtered into all nephrons, normally ~125 mL/min

Roughly how much filtrate is produced per day at a normal GFR?

About 180 liters per day

How many times per day is the entire 3 L of blood plasma filtered?

Approximately 60 times

Average daily urine output is about ____.

1 to 1.5 liters

What is the typical osmolarity range of concentrated urine?

Up to ~1200 mOsm/L

What is the typical osmolarity range of very dilute urine?

As low as ~50 mOsm/L

What is the approximate osmolarity of normal blood plasma?

~280–300 mOsm/L

Where does the majority (~75 %) of reabsorption occur?

In the proximal convoluted tubule (PCT)

Which nephron segment is the primary site for secretion (fine-tuning) of filtrate?

The distal convoluted tubule (DCT)

Write the equation that relates excretion to filtration, reabsorption, and secretion.

Excretion (E) = Filtration (F) – Reabsorption (R) + Secretion (S)

Filtration and secretion move substances in which direction?

From blood into the nephron tubule

Reabsorption moves substances in which direction?

From the nephron tubule back into the blood

How can the body raise a GFR that is too low?

Dilate the afferent arteriole and/or constrict the efferent arteriole to increase glomerular pressure

Name the three pressures affecting filtration in the renal corpuscle.

Glomerular hydrostatic pressure, capsular hydrostatic pressure, and colloid osmotic pressure

For net filtration to occur, which pressure must be greatest?

Glomerular hydrostatic pressure must exceed capsular and colloid osmotic pressures

What type of epithelium lines most of the nephron, including the PCT?

Simple cuboidal epithelium

Which membrane of a tubular epithelial cell faces the nephron lumen?

The apical surface

Which transporter on the apical membrane brings glucose into PCT cells?

The sodium-glucose cotransporter (SGLT) using Na⁺ gradient

How is sodium extruded across the basal membrane of PCT cells?

By the Na⁺/K⁺ ATPase (sodium-potassium pump)

Why does water follow solutes from the filtrate into blood?

Osmosis—water moves toward higher solute concentration

How does removal of water from filtrate favor potassium reabsorption?

Water loss concentrates K⁺ in the lumen, allowing it to diffuse into cells via channels or paracellular pathways

Concentrated urine usually indicates what physiological state?

Dehydration or low blood pressure

Dilute urine is typically produced in what situation?

High blood pressure or use of diuretic pharmaceuticals