1. Outer cortex 2. Inner Medulla

Chapter 17 Renal Physiology Flashcards by Jaime Bennett

What are some broad functions of the kidneys?

Regulate volume and components of extracellular fluid (plasma and interstitial fluid) by filtering the blood plasma into urine.
Regulate blood pressure through volume of blood plasma
Regulate the concentration of waste products in the blood
Regulate the concentration of electrolytes (Na+, K+, H+, HCO3-)
Regulate pH of body fluids
Secrete erythropoietin

How well did you know this?

Not at all

Perfectly

What stimulates secretion of the hormone erythropoietin from the kidneys and what does it cause?

They kidneys secrete the hormone erythropoietin in response to hypoxia (low oxygen conditions). This hormone stimulates the production of red blood cells in the bone marrow. This increases oxygen-carrying capacity.

How well did you know this?

Not at all

Perfectly

Trace the path of urine formation from the glomerulus to the toilet bowl. This includes the
nephron.

Nephron
Minor calyces -> major calyx
Renal Pelvis
Ureters
Bladder
Urethra

How well did you know this?

Not at all

Perfectly

Two layers of kidney

Outer cortex
Inner Medulla

How well did you know this?

Not at all

Perfectly

The outer cortex of the kidneys contains many _________.

Capillaries

How well did you know this?

Not at all

Perfectly

The Inner Medulla of the kidneys is composed of 7-18 renal _______ which are separated by renal ______.

-7-18 renal pyramids

-separated by renal columns

How well did you know this?

Not at all

Perfectly

The collecting ducts of nephrons empty into ______ which unite to form a ________.

minor calyces unit to form a major calyx

How well did you know this?

Not at all

Perfectly

What structures in the kidneys form the renal pelvis?

Major renal calyces

How well did you know this?

Not at all

Perfectly

The renal pelvis collects _____ and transports it to ______.

urine; ureters

How well did you know this?

Not at all

Perfectly

What are the 3 muscles involved with the bladder and urethra, and what type of muscle is each one?
When is each one constricted vs. relaxed during bladder filling and micturition?

Detrusor (bladder wall)- smooth muscle
-contracts: Micturition
-relaxes: filling of bladder
Internal Urethral Sphincter- smooth muscle
-contracts: filling of bladder
-relaxes: micturition
External Urethral Sphincter- Skeletal Muscle
-contracts: filling of bladder
-relaxes: Micturation

How well did you know this?

Not at all

Perfectly

The three muscles during micturition

Once the bladder is full and it is time to urinate:

-detrusor contracts
-internal + external urethral sphincter relax

How well did you know this?

Not at all

Perfectly

The three muscles during filling of the bladder

While the bladder is filling with urine:

-detrusor is relaxed

-internal urethral sphincter is constricted

-external urethral sphincter is constricted

How well did you know this?

Not at all

Perfectly

What are parts of the
nervous system contribute to
-Bladder filling
-Bladder emptying/ urination

Bladder filling:

-Sympathetic nervous system relaxes detrusor and constricts internal urethral sphincter
-Somatic nervous system stimulates external urethral sphincter to constrict (voluntary)
-Norepinephrine

Bladder emptying:
-Parasympathetic nervous system contracts detrusor and relaxes internal urethral sphincter
-somatic nervous system signals eus to relax

How well did you know this?

Not at all

Perfectly

The volume of plasma (blood) delivered to kidneys over time (mL/min) is called ______________.

What % is this of total cardiac output?

Renal plasma (blood) flow (RPF)

RPF is 22% of cardiac output

How well did you know this?

Not at all

Perfectly

What is the renal plasma/blood flow?

The volume of blood that gets delivered to the kidneys over time?

How well did you know this?

Not at all

Perfectly

What are the units of measurement of renal plasma/blood flow?

mL/min

How well did you know this?

Not at all

Perfectly

How much cardiac output do the kidneys get?

22%

How well did you know this?

Not at all

Perfectly

How much of renal plasma/blood flow do the glomeruli get?

The glomeruli receive approximately 20% of the renal plasma flow, which is about 1/5th of the total renal blood flow and 4-5% of cardiac output.

How well did you know this?

Not at all

Perfectly

Trace the path of renal blood flow starting on the arterial side with the afferent arteriole to
the venous side

Afferent arteriole -> glomerulus (1st capillary) -> efferent arteriole -> peritubular capillaries (2nd capillary)

How well did you know this?

Not at all

Perfectly

How many nephron units are in each kidney?

10^6

How well did you know this?

Not at all

Perfectly

The vascular component of the kidneys is the __________. All of the renal plasma flow passes through this.

glomerulus

How well did you know this?

Not at all

Perfectly

Tubular components of the Nephron

Glomerular (Bowman’s) Capsule -> proximal convoluted tubule (PCT) -> Loop of Henle (LOH– descending limb -> thin ascending limb -> thick ascending limb) -> Distal convoluted tubule (DCT) -> Collecting duct (cortical then medullary) -> empties into calyx

How well did you know this?

Not at all

Perfectly

Loop of Henle is composed of

Descending Limb
Thin Ascending Limb
Thick Ascending Limb

How well did you know this?

Not at all

Perfectly

The Renal Corpuscle includes

(1) Glomerulus
(2) Bowman’s Capsule

How well did you know this?

Not at all

Perfectly

Nephrons are situated in the _______ descending down into the renal ______.

Situated in cortex and descend down into the renal pyramids.

The collecting ducts from nephrons drain into the _______.

Minor calyces

Types of Nephrons

1. Cortical Nephrons 2. Juxtamedullary Nephron

Cortical Nephrons originate in _________. Juxtamedullary Nephrons originate in _______.

Outer 2/3 of cortex Inner 1/3 of cortex

How does the loop of henle differ between cortical and juxtamedullary nephrons

-Cortical nephrons have a short, thick loop of henle that is mainly located in the cortex but a small portion of it dips into the medulla. -Juxtamedullary nephrons have long, narrow loops of henle that extend deep into the medulla.

Cortical nephrons are more involved in ______.

Reabsorption of ALL solutes and waste secretion.

Juxtamedullary nephrons are important for producing _________ via _______.

Producing concentrated urine via salt and water reabsorption.

What type of nephron has a more developed vasa recta?

Juxtamedullary

Glomerulus is the tangle of _________.

Capillaries

Glomerular (Bowman's Capsule) surrounds the Glomerular and is composed of how many layers?

Bowman's Capsule is composed of 2 layers: (1) Inner Layer -- composed of podocytes and lines the blood vessels Glomerular (Bowman's) Space in between these Layers (2) Outer Layer-- rounded and encompasses the entire glomerulus (Bowman's Capsule)

Glomerulus is ____ of blood vessels -_______ arteriole in -_______ arteriole out

-tuft of blood vessels Afferent = in Efferent = out

The fluid that enters the glomerular space (between inner and outer layer of Bowman's Capsule) and travels into the proximal convoluted tubule is called _________.

Ultrafiltrate (filtrate)

Ultrafiltrate (Filtrate) is the fluid that enters glomerulus ______ and travels into the ____________ tubule.

Enters glomerulus spaces and travels into the proximal convoluted tubule

The ultrafiltrate in glomerulus must pass through, in order, what structures?

(1) Fenestrated capillary (large pores in the endothelium) (2) Basement Membrane (not cells) (3) Slits in the processes of podocytes (comprise the inner layer of the glomerular capsule. -Split diaphragms span the slits

The Finestrated capillary is 100-400 times more permeable to plasma _____, and solutes such as _____ and _______. These large pores in the endothelium are small enough to prevent ______, _______, ______ and _________ from passing through the pores.

-100-400 times more permeable to plasma H2O, and solutes (electrolytes and glucose) -small enough to prevent RBCs, platelets, WBCs, and large proteins

Plasma proteins are mostly excluded from the filtrated due to ___________ and _________.

-large size and can't fit through pores in endothelium -Negative charge of proteins is repelled by negative charge of the basement membrane

The Basement Membrane and Slit Diaphragms of Podocytes are lined with __________ charges which repel ______-charged ________.

lined with negative charges and repel negatively-charged proteins

Glomerular filtrate has low ______ concentration.

Protein

Filtered Proteins are reabsorbed by __________. Are proteins in urine then?

renal epithelial cells -No proteins in urine

What are two general causes of proteinuria?

(1) Damage to filtration membrane may allow large proteins to pass through and enter the urine. (diabetes, hypertension, glomerulonephritis) -damage to fenestrated capillary -damage to basement membrane -damage to slits in processes of podocytes (2) Overproduction of proteins- the production of too many proteins that surpasses the capacity for renal epithelial cells to reabsorb

Proteinuria

excess of protein in urine -diabetes

What types of solutes freely enter the filtrate vs. which ones are restricted and remain in the glomerular capillaries? What about proteins and what normally happens to proteins that enter the filtrate? Based on the above, what are 2 general causes for excessive protein in the urine (proteinuria).

Freely enter filtrate: small size, no charge -ions -glucose -amino acids -urea Restricted and Remain in Glomerular capillaries: large size, negative charge: -plasma proteins (Basement membrane and slit diaphragms are lined with negatively charged glycoproteins) Proteins that enter the filtrate are reabsorbed by renal epithelial cells. Caused for Proteinuria: -damage to glomerulus -damage to renal tubules

What are the forces driving and countering glomerular filtration?

Driving: (1) Hydrostatic Pressure of blood traveling through capillaries (2) Colloid Osmotic pressure of Glomerular Filtrate Countered: (1) Hydrostatic pressure of glomerular filtrate (2) Colloid osmotic pressure of plasma

The net outward filtration pressure into glomerular capsule is _______ mm Hg/

10 mm Hg

What is GFR? What are the units?

Glomerular Filtration Rate (mL/min) Volume of filtrate produced by both kidneys each minute GFR correlates to renal function

Where does fluid go that is not filtered by the glomerulus into the filtrate?

Returned to circulation via the efferent arteriole -> peritubular capillaries -> vasa recta -> venous blood

If the glomerular filtration rate is 7.5 L/hour or 18- L/day, without reabsorption of salt and water, this would lead to ________ and _______.

dehydration and electrolyte imbalance

Volume of urine is ~____ L/day

1-2

What % of filtrate is reabsorbed?

99% is reabsorbed and the other 1% is urine

Obligatory Water Loss is the ______ urine volume required to _________.

minimal urine volume required to excrete metabolic waste (400-600 mL)

Filtration

from the glomerulus to form the filtrate

Reabsorption

Brings water and solutes back out of the filtrate into the plasma along the rest of the nephron

Secretion

Secretion of solutes into the filtrate for excretion or elimination

Quantity of a solute secreted

(quantity filtered + quantity secreted) - Quantity reabsorbed

What is renal excretion/elimination rate of a solute and what are its units of measurement? Be able to calculate the amount of a solute excreted based on the quantities filtered, secreted, and reabsorbed

Renal Excretion Rate is the quantity of a solute excreted per minute (mg/min) =V (rate of urine formation, mL/min) x U (concentration of solute x in urine, mg/mL)

Renal Plasma Clearance Rate

-Ability of the kidneys to remove a specific solute (x) from plasma and excrete those molecules into the urine

Transcellular Movement of Solutes during Renal Reabsorption

Travels through the tubular cells: (1) Filtrate in the lumen of tubule (2) Transports across the apical membrane into the tubule cell (3) Diffuses through the cytosol of the tubule cell (4) Transports out of the Basolateral membrane into the interstitial fluid (5) Moves through the interstitial fluid and into the capillary

Paracellular Route of Renal Solute Reabsorption

Travels between tubular cells through leaky, tight junctions (in PCT) (1) Filtrate in lumen (2) moves through tight junction between tubule cells (3) travels through interstitial fluid and into the capillary

Which fluid compartment does transcelluar route involve that paracellular does not?

The intracellular fluid (ICF)

Approximately ____% of filtered salt and water is reabsorbed across PCT, ____% is reabsorbed across LOH

65%; 20%

Salt transport in what two regions are NOT under hormonal control?

Proximal Convoluted Tubule and Loop of Henle

Only ___% of initial filtrate remains to enter Distal convoluted tubule (DCT) and collecting duct (CD) This remaining % is reabsorbed variably, depending on the level of ______ and the concentration of ______ in the body.

15%; hydration and electrolyte

Salt and Water transport in the _____ nephron are hormonally regulated by what two hormones?

Distal; Vasopressin (ADH) and Aldosterone

Reabsorption of Na+ in Proximal Convoluted Tubule: Na+ is transported across the apical membrane via _____________ (also referred to as ___). What kind of transporter? Is energy spent?

Facillitated Diffusion/ Secondary active transport Na+ / Glucose Cotransporter No energy is spent

Reabsorption of Na+ in Proximal Convoluted Tubule: Na+ is transported across the basolateral membrane via _______ transport using what kind of transporter? Does this require energy?

primary active transport Na+ K+ Pump Requires use of Energy

Reabsorption of Na+ in Proximal Convoluted Tubule: Na+ ________ across interstitial space into systematic capillaries.

Diffuses

Reabsorption of Na+ in Proximal Convoluted Tubule: Na+ Reabsorption in PCT is considered _______ dependent.

energy

Reabsorption of Na+ in Proximal Convoluted Tubule: Reabsorption of Na+ in PCT uses ___% of total energy expenditure of the body to reabsorb ___% of the filtrate.

6% of energy to reabsorb 65% of the filtrate

Reabsorption in Proximal Convoluted Tubule: ___ follows Na+ due to the electrical attraction. This follows the _____-cellular route.

Cl- Paracellular route

Reabsorption in Proximal Convoluted Tubule: ______ (~150 L/day) follows the osmotic pressure of salt out of the Proximal Convoluted Tubule into interstitium then to blood (peritubular capillaries) What happens to osmolarity?

Water follows salt Osmolarity does NOT change

The PCT is highly permeable to ____ due to having ____ channels

WATER; aquaporin

What is the total [solute] in the PCT?

300 mOsm (isotonic- the concentration of solutes inside and outside of the cell is the same, resulting in no net movement of water.)

Glucose and Amino Acids are easily filtered by glomeruli. Normally all of the filtered glucose and amino acids are reabsorbed by_________ (also known as _____ transport) in the PCT.

facilitated diffusion (secondary active transport)

Primarily _____ nephrons are responsible for water and salt reabsorption due to having a concentration gradient in renal _____.

juxtamedullary; conc gradient in renal medulla

In order for H2O to be reabsorbed , medullary interstitial fluid must be ________ relative to tubular fluid.

hypertonic