Renal & Urinary System

Eliminate waste and regulate volume and composition

-filter blood plasma

-regulate bv

-osmolarity of body fluids

Kidneys fundamental role

Glucose

In times of starvation, the kidneys will make ________

Waste

any substance that is useless to body or in excess of the bodies needs

Nitrogen

Most toxic of our metabolic wastes

Urea

The liver converts ammonia to ________ because its significantly less toxic

Gout

Too much uric acid leads to

BUN

An expression of the level of nitrogenous waste in the blood

Azotemia

INCREASED BUN - indicates renal insufficiency (not filtering waste); may progress to uremia

Uremia

a syndrome of diarrhea, vomiting, dyspnea, and cardiac arrhythmia all due to the toxic effects as wastes accumulate

Cortex

The _______ is the outer area of the kidney

Medulla

The _______ is the inner area of the kidney that surrounds the renal sinus

Major and minor

There are _______ calyx and _______ calyx in the kidenys

Renal pelvis

enlarged chamber formed by 2-3

major calyces

Ureter

tubular continuation of renal pelvis that drains urine to bladder

Artery → Afferent arteriole → Glomerulus → Efferent arteriole → Capillaries/Vasa recta → Vein

Describe circulation through the kidney

Nephron, cortex

The _______ is the functional unit of the kidney, located in the _______

Renal corpuscle

Renal tubule

__________: where blood plasma is filtered

_________: where plasma filtrates into urine

Bowman's capsule, proximal tubule, loop of henle, distal tubule

What are the 4 parts of the nephron

2, parietal and visceral

The bowman's capsule has ____ layers and they are ______ and _______

podocytes

The visceral layer consists of _______

Capsular

The ______ space is found between the parietal and visceral layers in the bowman's capsule

Glomerular filtrate

What collects in the capsular space?

Network of capillaries

-vascular and urinary pole

What is the glomerulus? What are its "poles"?

PCT

longest, most coiled, simple cuboidal with brush border (microvilli)

Ascending and descending

The loop of henle has a ______ portion and ________ portion

Thick segment

part of descending limb and

most of ascending limb, active transport of salts

Very water permeable

Unique feature of thin segment of loop of henle

Renal corpuscle → PCT→ nephron loop →DCT → collecting duct→ papillary duct →minor calyx → major

calyx → renal pelvis →ureter → urinarybladder → urethra

*****What is the flow of glomerular filtrate from start to finish?******

Cortical (95%)

Juxtamedullary

What are the 2 types of nephrons

juxtamedullary nephrons

This neuron helps maintain salt gradients and conserve water

-glomerular filtration

-tubular reabsorption/secretion

-water conservation

The kidney converts blood plasma to urine. How?

fenestarted capillary, basement membrane, filtration slits

The filtration membrane must pass....

Negative, to repel albumin

the basement membrane has a (positive/negative) charge. Why?

Protein and blood are seen in urine

If the filtration membrane is damaged then...

The high pressure causes the vessel walls to thicken and narrow, reducing blood flow to the nephrons.

How can hypertension affect kidney function?

Glomerulus. It has large afferent arterioles and small efferent arterioles

Blood hydrostatic pressure is much higher in the _______ than anywhere else in the body. Why?

High, kidneys

Because the "blood pressure" within the glomerulus is already________, the ______ are particularly vulnerable to systemic hypertension

GFR

Amount of filtrate formed per minute by both kidneys

combined

Dehydration, electrolyte depletion

Increased GFR indicates

Less filtrate is being formed and less water removal

Decreased GFR indicates

Adjusting glomerular bp

Yes, by causing smooth muscle to contract when stretched and tubuloglomerular feedback

How is GFR controlled?

Do neurons adjust their own blood flow? How?

Myogenic

Stretches, constricts, decreases

________ mechanism: smooth muscle will contract when stretched

Systemic increased BP → _______ afferent arteriole → afferent arteriole

________ → (increases/decreases) blood flow

Juxtaglomerular apparatus

a complex of structures

found at very end of loop of Henle. Contains 3 special cell

types

Macula densa, JG cells, mesangial cells

3 cells that make up juxtagomerular apparatus

JG

These cells of the juxtaglomerular apparatus vasodilate/vasoconstrict arterioles

Mesangial

These cells of the juxtaglomerular apparatus can contract glomerular

capillaries to reduce filtration OR relax to increase blood flow & filtration

Macula densa

These cells of the juxtaglomerular apparatus send signals to constrict AFFERENT arteriole to DECREASE GFR

High BP causes a rapid flow of filtrate into renal tubules.

The macular densa senses this and secretes paracrine.

Constriction of afferent arterioles occurs to reduce GFR

How does control of GFR act as a negative feedback system?

JG

______ cells release renin

Stimulates widespread vasoconstriction

Reduces GFR/water loss

Secretes aldosterone and ADH

What are the effects of angiotensin II on the kidney

Reabsorbs 65% of the glomerular filtrate.

Sodium is reabsorbed

Role of PCT

Sodium

Most important ion reabsorbed by PCT

Secondary active transport

Na/K pumps

Paracellualr and transcellular routes

How is chloride reabsorbed by the PCT?

Co-transport with NA using symports called SGLTs then enters capillaries via facilitated diffusion

How is glucose reabsorbed by the PCT?

Paracellular route w water

How are electrolytes (K, MG, P) reabsorbed by the PCT?

Urea diffuses through tubule epithelium with water

How is nitrogenous waste reabsorbed by the PCT?

Increases

As volume of filtrate decreases, concentration of urea (increases/decreases)

Yes

No, too large

Yes

Does the PCT reabsorb uric acid? Creatinine? Water?

peritubular capillaries

Reabsorption of water and solutes occurs at the

High, low

A (low/high) colloid osmotic pressure and (low/high) blood hydorsotatic pressure favors water reabsorption

remaining solute molecules will escape being reabsorbed and spill into urine

If all transporters are occupied, then....

waste removal and acid-base balance

What is tubular secretion of the PCT

Generates solute gradient

Ascending (thick)

Loop of henle primary function?Which segment is impermeable to water?

Ascending (thick)

Descending (thin)

The _______ segment is not permeable to water, the ______ segment is highly permeable to water

Aldosterone, ANP, ADH, PTH

Which hormones regulate DCT and the collecting ducts?

Aldosterone

A drop in BP triggers

The posterior pituitary to secrete ADH to INCREASE waster reabsorption

Dehydration stimulates....

ANH, increases

_______ is released in response to HIGH BP, (increases/decreases GFR)

PTH

________ is released due to LOW blood calcium levels

Loop of henle

Reabsorbs another 25% of filtrate

• Primary role is to aid the function of collecting duct

PCT

Reabsorbs ~ 65% of glomerular filtrate and returns it to the

blood of peritubular capillaries

• reabsorption occurs via osmotic and cotransport linked to active

transport of sodium ions

DCT

Reabsorbs more sodium, chloride, and water

• Rates are subject to control by hormones

• Extract drugs, waste

Collecting duct, cortex

The _______ conserves body water and begins in the ________

High

In order to concentrate urine (and

prevent a large volume of water from being lost), the kidney must maintain a (low/high) concentration of solutes in the medulla

Proximal tubules

Na+ and other substances

removed are removed in _________

• Water follows passively

• Filtrate volume reduced

Descending loop of henle

In the ________ water exits passively, solute enters

Ascending limb

In the ________ Na+, Cl-, K+ transported out of filtrate

• Water remain

Clear to light yellow

Bacterial growth

Urine is normally which color? What does cloudy urine suggest?

Hydration

50 mOsm/L indicates (hydration/dehydration)

Dehydration

1200 mOsm/L indicates (hydration/dehydration)

Oliguria

<500mL/day is

Anuria

>100 mL/day is

Polyuria

>2L/day is

2 L

Normal amount of urine we should expel a day

diabtes

Any metabolic disorder resulting in chronic polyuria

DM

For (DM/DI), the polyuria results

from high concentrations of glucose in renal tubule

DI

For (DM/DI), the polyuria results from insufficient ADH secretion. This means the collecting duct doesn't reabsorb much water

Increase urine volume and lower bp

How do diuretics work?

Internal

External

The (internal/external) urinary sphincter contains smooth muscle

the (internal/external) urinary sphincter contains skeletal muscle

Sacral spinal cord

When voiding urine, stretch receptors send signals to