AUBF RENAL FUNCTION

PRELIM

shape of kidney

bean shaped

Kidney is located on

the posterior abdominal wall in the area

n the posterior abdominal wall in the area known as

the retroperitoneum

An adult human kidney has a mass of approximately

150 g

kidney measures roughly

12.5 cm in length

What is the width of the kidney?

6cm

Depth of kidney

2.5 cm

Each kidney contains approximately

1-1.5 million nephrons

Each kidney contains approximately 1-1.5 million functional units called

Nephrons

makes up approximately 85% of the total nephron

Cortical nephron

Cortical nephron can found mainly in the?

the cortex of the kidney

Responsible primarily for removal of waste products and reabsorption of nutrients.

Cortical nephron

Primary function is the concentration of urine

juxtamedullary nephrons

Have loops of Henle that extend deep into the medulla of the kidney.

Juxtamedullary nephrons

EXCRETORY FUNCTION

A. Glomerular filtration

B. Tubular Reabsorption

C. Tubular Secretion

EXCRETORY FUNCTION

•Regulation of water balance in the body.

• Regulation of acid-base balance

• Regulation of electrolytes

• Regulation of bloop pressure through secretion of renin

• Stimulates Erythropoiesis through secretion of EPO

SUPPLIES BLOOD TO THE KIDNEY

THE RENAL ARTERY

THE HUMAN KIDNEY RECEIVES APPROXIMATELY \____ OF THE BLOOD PUMP.

25%

TOTAL RENAL BLOOD FLOW:

1200ML/MIN

RENAL PLASMA FLOW:

600-700 ML/MIN

IT SUPPLIES BLOOD INDIVIDUALLY TO THE GLOMERULUS OF EACH NEPHRO

AN AFFERENT ARTERIOLE AT THE VASCULAR POLE

ORDER OF BLOOD FLOW IN THE NEPHRON

RENAL ARTERY→ AFFERENT ARTERIOLE→ GLOMERULUS→ EFFERENT ARTERIOLE→ PERITUBULAR CAPILLARIES→ VASA RECTA→ RENAL VEIN

ORDER OF URINE FORMATION FROM THE NEPHRON

GLOMERULUS→ BOWMAN'S CAPSULE → PCT → DLH →ALH→DCT→ COLLECTING DUCTS

The glomerulus consists

- A coil of approx 8 capillary lobes

referred to collectively as the capillary tuft. It resembles as

sieve

Location of glomerulus

within the Bowman's capsule.

non-selective filter for plasma substances with molecular weights

molecular weights of less than

with molecular weights of less than

A non-selective filter for plasma substances w

Normally, the fluid leaving the glomerulus has a specific gravity of

1.010

as it leaves the glomerulus shows the filtrate to have a specific gravity of 1.010 and confirms that it is chemically an ultrafiltrate of plasma.

Analysis of the fluid

the glomerulus shows the filtrate to have a specific gravity of \_______ and confirms that it is chemically an ultrafiltrate of plasma

1.010

Measurement of renal plasma filtered

Approximately 120 mL/min, or one fifth,

How the renal plasma is filtered?

through the glomeruli forming what is known as the ultrafiltrate,

ultrafiltrate

the fluid resulting from the initial filtration of metabolic by-products from the filtered blood within the tubule of the kidney

Approximately 120 mL/min, or one fifth, of the renal plasma is filtered through the glomeruli forming what is known as\________________________is further processed as it travels through the nephron

ultrafiltrate

has the same composition as blood plasma but it is normally free of protein except for about 10 mg/dL of low molecular weight protein

Ultrafiltrate

The ultrafiltrate has the same composition as blood plasma but it is normally free of protein except for about

10 mg/dL of low molecular weight protein

PLASMA FILTRATE MUST PASS THROUGH THREE CELLULAR LAYERS:

1\. CAPILLARY WALL MEMBRANE

2\. BASEMENT MEMBRANE

3\. VISCERAL EPITHELIUM OF BOWMAN'S CAPSULE

\

BARRIER'S THAT PROHIBITS THE FILTRATION OF LARGE MOLECULES

• THE CAPILLARY WALL OF GLOMERULUS IS FENESTRATED

• INTERTWINING FOOT PROCESSES - PODOCYTES \n • SHIELD OF NEGATIVITY - REPELS MOLECULES WITH A NEGATIVE CHARGE EVEN MOLECULES ARE SMALL ENOUGH TO PASS (EXAMPLE: ALBUMIN)

THE CAPILLARY WALL OF GLOMERULUS IS

FENESTATED

INTERTWINING FOOT PROCESSES

podocytes

Shield of negativity

- REPELS MOLECULES WITH A NEGATIVE CHARGE EVEN MOLECULES ARE SMALL ENOUGH TO PASS (EXAMPLE: ALBUMIN)

GLOMERULAR PRESSURE

JUXTAGLOMERULAR APPARATUS- MAINTAINS THE GLOMERULAR BLOOD PRESSURE

• A. JUXTAGLOMERULAR CELL -FOUND IN THE AFFERENT ARTERIOLE, SECRETES THE RENIN ENZYME \n • B. MACULA DENSA -FOUND IN THE DCT, SENSOR OF CHANGE IN BLOOD PRESSURE

MAINTAINS THE GLOMERULAR BLOOD PRESSURE

JUXTAGLOMERULAR APPARATUS

FOUND IN THE AFFERENT ARTERIOLE, SECRETES THE RENIN ENZYME

JUXTAGLOMERULAR CELL

FOUND IN THE DCT, SENSOR OF CHANGE IN BLOOD PRESSURE

MACULA DENSA

IF IT WERE NOT FOR\____________, ALL ROUTINE URINES WOULD HAVE POSITIVE REAGENT STRIP READINGS FOR PROTEIN/ALBUMIN.

THE SHIELD OF NEGATIVITY

DILATION OF AFFERENT ARTERIOLE, CONSTRICTION OF EFFERENT ARTERIOLE

DECREASE BLOOD PRESSURE

CONSTRICTION OF AFFERENT ARTERIOLE, DILATION OF EFFERENT ARTERIOLE

INCREASE BLOOD PRESSURE

RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM (RAAS)

a hormone cascade pathway that helps regulate blood pressure and blood volume

A system regulates the flow of blood to and within the glomerulus

RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM (RAAS)

RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM (RAAS) system responds to the?

blood pressure and plasma sodium content that are monitored by the juxtaglomerular apparatus

blood pressure and plasma sodium content that are monitored by?

juxtaglomerular apparatus

consists of the juxtaglomerular cells in the afferent arteriole and the macula densa of the distal convoluted tubule

juxtaglomerular apparatus

Controls the regulation of the flow of blood to and within the glomerulus.

RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM (RAAS)

Primary electrolyte affected when RAAS is activated:

sodium

RAAS (renin-angiotensin-aldosterone system) functions

• 1. Dilation of the afferent arteriole and constriction of the efferent arteriole

• 2. Stimulation of sodium reabsorption in the proximal convoluted tubule

• 3. Triggers the adrenal cortex to release the sodium-retaining hormone, aldosterone, to cause reabsorption of sodium and excretion of potassium in the distal convoluted tubule and collecting duct \n • 4. Trigger release of antidiuretic hormone by the hypothalamus to stimulate water reabsorption in the collecting duct

\

It dilates the afferent arteriole and constriction of the efferent arteriole

Functions of RAAS

RAAS stimulates the \______________________ in the proximal convoluted tubule

sodium reabsorption

Stimulation of sodium reabsorption happens in the

proximal convoluted tubule

Triggers the adrenal cortex to release the sodium-retaining hormone, aldosterone, to cause reabsorption of sodium and excretion of potassium in the distal convoluted tubule and collecting duct

Functions of RAAS

RAAS trigger the adrenal cortex to release

the sodium-retaining hormone, aldosterone, to cause reabsorption of sodium and excretion of potassium in the distal convoluted tubule and collecting duct

Triggers the adrenal cortex to release the sodium-retaining hormone, aldosterone, to cause reabsorption of sodium and excretion of potassium in

n the distal convoluted tubule and collecting duct

RAAS triggers and release \______________ hormone by the hypothalamus to stimulate water reabsorption in the collecting duct

Antidiuretic hormone

The body must not lose \_________of water-containing essential substances every minute

120ml

The loss of tubular function is capability is often the first function affected

renal disease

Urine composition

95% water and 5% solutes

Urine composition: 5 % solutes

Total solute in 24'hours \= 60 grams

(35 grams organic substances, 25 grams inorganic substances)

UC : Total solute in 24 hours

60 grams

UC: Total solute in 24 hours contains

- 35 grams of organic substance

- 25 grams inorganic substances

TWO MECHANISM OF TUBULAR REABSORPTION:

Active and Passive transport

the substance to be reabsorbed must combine with a carrier protein contained in the membranes of the renal tubular cells. This transport requires energy

Active transport

the movement of molecules across a membrane as a result of differences in their concentration or electrical potential on opposite sides of the membrane. It is Characterized by movement of a substance from an area of higher concentration to one of lower concentration

Passive transport

Active Transport substance

* Glucose, Amino acid, Salts
* Chloride
* Sodium

\

Active Transport location

\-Proximal convoluted tubule

\-Ascending loop of Henle \n -PCT and DCT

\

Passive Transport substance

* Water
* Urea 40% are (reabsorbed)
* Sodium

Passive Transport location

* PCT, DCT, DLH -Proximal convoluted tubule
* ascending loop of Henle

Takes place in all parts of the nephron except the ALH.

Passive reabsorption of water

Sodium is actively transport in all part of the nephron except in

the Ascending loop of henle

Denoted Tm, the maximal rate of reabsorption of a solute by the tubular epithelium per minute (milligrams per minute). Reabsorptive capacity varies with each solute and depends on the glomerular filtration rate

Maximal Tubular reabsorptive capacity

varies with each solute and depends on the glomerular filtration rate

Reabsorptive capacity

transport maximum (Tm)

the maximal rate of secretion or reabsorption of a substance by the renal tubules.

Maximal Tubular reabsorptive capacity - Denoted Tm, the maximal rate of reabsorption of a solute by the tubular epithelium per

minute (milligrams per minute)

Where does active transport stops is termed the renal threshold

The plasma concentration

Sodium renal threshold is

110-130 mmol/L

Where does renal concentration begins?

In the descending and ascending loop of henle and the final concentration of urine continues to the Collecting Duct.

Where does the final concentration of urine continues?

To the Collecting Duct

In renal concentration water is remove by?

by osmosis in the descending loop of Henle

Renal absorption it is reabsorbed in the ascending loop

Sodium and chloride

In renal concentration it is removed by osmosis in the descending loop

Water

The movement of water across a semipermeable membrane in an attempt to achieve an osmotic equilibrium between two compartments or solutions of differing osmolality (i.e., an osmotic gradient). This mechanism is passive, that is, it requires no energy

Osmolality

Excessive reabsorption of water as the filtrate passes through the highly concentrated \_____________ is prevented by the water impermeable walls of the ascending loop

medulla

what does the water impermeable walls of the ascending loop prevented?

Excessive reabsorption of water as the filtrate passes through the highly concentrated medulla

countercurrent mechanism

Part of the process by which the kidneys concentrate urine

countercurrent mechanism

Excessive reabsorption of water as the filtrate passes through the highly concentrated medulla is prevented by the water impermeable walls of the ascending loop

serves to maintain the osmotic gradient of the medulla

the countercurrent mechanism