Renal Anatomy and physiology Ppt 2 and 3

What is the anatomy of the kidney?

Shape: Bean-shaped organ

Color: Reddish-brown

Size: About 10-12 cm long (4-5 inches), size of a fist

Location: In the back of the abdominal cavity

Placement: One on each side of the spine, right kidney sits slightly lower than the left (because of the liver)

Protected by: Lower ribs, muscles, and a layer of fat

What is the renal cortex?

Outer layer of the kidney

Contains glomeruli and parts of the nephron

Filters Blood to form urine

What is the Renal medulla?

Inner region beneath the cortex

Contains renal pyramids

Helps concentrate urine

What are the renal pyramids?

Cone-shaped structures in the medulla

Carry urine form nephrons to the papilla

What is the papilla?

Tip of each pyramid

Drains urine into the minor calyces

What are the Minor and Major Calyces?

Funnel-shaped spaces

Collects urine from the papillae and pass it tot he renal pelvis

What is the renal pelvis?

Central collecting area

Transfers urine from the calyces to the ureter

What is the Nephron?

It is the functional unit of the kidney

Produces urine in the process of removing waste and excess substances from the blood

What is the Bowman’s capsule?

Surrounds the glomerulus

Collects fluid filtered from the blood

What is the Proximal Convoluted Tubule (PCT)

Returns needed substances to the blood

Reabsorbs water, glucose, amino acids, and electrolytes

What is the ascending loop of Henle?

Reabsorbs sodium and chloride

What is the descending loop of Henle?

Reabsorbs water

What is the Distal Convoluted Tubule? (DCT)

Fine-tunes salt and water balance

Contains macula densa (senses sodium and regulates filtration rate)

What is the collecting duct?

Final water reabsorption

Carries urine to renal papilla → calyces → pelvis → ureter

What is the order of Renal Blood Flow?

1. Renal Artery

2. Afferent arteriole

3. Glomerulus

4. Efferent Arteriole

5. Pertibular Capillaries and Vasa Recta

6. Renal Vein

What makes up the Renal System?

The ureters, bladder and urethra

What is the process of Glomerular Filtration?

1. Blood enters the glomerulus through the afferent arteriole

2. Hydrostatic pressure pushes water and small solutes (like glucose, sodium, urea) out of the blood

3. These substances pass through the glomerular filtration barrier into the Bowman’s capsule

4. Large proteins and blood cells stay in the bloodstream

What is the Normal Glomerular Filtration Rate?

120 mL/min

What is the glomerular filtration barrier made up of?

1. Endothelial cells

2. Basement membrane

3. Podocytes

What allows water and small solutes to pass and blocks proteins and cells?

Glomerular Filtration Barrier

What is the first step of urine formation?

Glomerular Filtration: Water and small solutes are filtered from blood into Bowman’s capsule

What is the second step in urine formation

Tubular Reabsorption: Substances the body needs (ex: glucose, amino acids, sodium, water) are reabsorbed from the nephron tubules back into the blood

Occurs mostly in the proximal convoluted tubule

What is the third step in urine formation?

Tubular Secretion: Waste products and excess ions (ex: H+, K+, drugs) are secreted from the blood into the tubule

Helps maintain pH balance and remove toxins

Requires energy (ATP) and moves substances against a concentration gradient (low → high)

Active transport

Does not require energy, moves substances with the concentration gradient (high → low)

Passive transport

how do the kidneys regulate pH?

1. Reabsorbs Bicarbonate

2. Secretes Hydrogen Ions

   1. Excretes Acid Forms

A hormone system that helps regulate blood pressure, blood volume, and sodium balance

Renin-Angiotensisn-Aldosterone System (RAAS)

Released by the kidneys when blood pressure or sodium is low, starts the RAAS cascade

Renin

Formed after a series of steps, causes blood vessels to constrict (raises blood pressure), stimulates aldosterone lease

Angiotensin II

A hormone from the adrenal glands (on top of each kidney), increases sodium and water reabsorption in the kidneys, helps raise blood volume and pressure

Aldosterone

What is the normal urine volume?

About 1-2 liters per day

Varies with fluid intake, hydration, hormones, and health

What is the Normal Solute Composition?

95 percent water

5% solutes: urea (from protein breakdown), creatinine, electrolytes (Na, K, Cl), uric acid, small amounts of other waste products

Urine output greater than 2,500 mL per day

Polyuria

Urine output less than 100 mL per day

Anuria

urine output less than 400 mL per day (“Low output”)

Oliguria

Where is the Antidiuretic Hormone come from? (ADH)

Produce in the hypothalamus (brain)

What triggers ADH release?

High blood osmolality (too concentrated)

Low blood volume or low blood pressure

Dehydration

Increases water reabsorption into the bloodstream and acts on the collecting ducts in the kidneys

ADH