Human Bio Exam 5 - Ch 16

Functions of the kidneys

• Filter blood and excrete waste

• Regulate blood volume and blood pressure

• Regulate electrolyte and acid-base balance

• Secrete erythropoietin

Erythropoietin

Hormone excreted by kidneys to stimulate the production of RBCs

Anatomy of kidney

• Renal capsule - surrounds entire kidney to hold its shape the

• Hilum - Where renal artery and renal vein connect. Also where ureter exit.

• Renal cortex - Around outside of middle. Form outer 1 cm and renal columns.

• Renal medulla - Middle. Divided into pyramids.

Urine is produced more in the cortex but is drained into the pyramids to their point, and then out the ureter.

Renal capsule

surrounds entire kidney to hold shape

Hilum

Where renal artery and renal vein connect. Also where ureter exit.

Renal cortex

Around outside of middle. Form outer 1 cm and renal columns.

Renal medulla

Middle. Divided into pyramids.

Nephron

Microscopic unit of kidney; unit of urine production. Each kidney has about 1.2 million. 2 parts - Renal corpuscle and renal tubules

Renal corpuscle

The body of blood vessels. 2 parts - Glomerulus and glomerular capsule

Glomerulus

Cluster of bv in nephron. Surrounded by capsule. Filters out substances from blood.

Glomerular capsule

Catches filtrate (preurine)

Renal tubules

Tubes of a nephron. Contains - proximal convoluted tubule, nephron loop, distal convoluted tubule, and collecting duct.

Nephron Loop

Big U shaped loop in the middles of tubules

Proximal convoluted tubule (PCT)

The tubes with a lot of twists and turns close to the bundle of bv

Distal convoluted tubules (DCT)

The tubes with a lot of twists and turns farther away from the bundle of bv

Collecting duct

Collects all stuff from about 12 different nephrons and continues urine formation.

Steps of urine formation

1. Filtration (Corpuscle) takes substances from blood → filtrate

2. Reabsorption (PCT, Loop, DCT) filtrate → blood

3. Secretion (PCT, Loop, DCT) blood → filtrate

4. Water conservation (Collecting duct) filtrate → blood

Last filtrate is what urine is. Once it reaches the collecting duct, urine is not changed. Only transported!

Ureters

Transports urine. 2 Muscular tubes that run from the kidneys to the bladder. Empty about every 30 seconds.

Bladder

Stores urine. Muscular sac that lies behind the pubic symphysis. Smooth muscle that we do not control.

Urethra

Transports urine out of the body. Different lengths between males and females because males have a prostate and penis that it goes through.

Why are UTIs more common in females?

Female urethra is so short so it’s easier for bacteria to travel. Female urethra is also close to the anus.

Urine should not contain…?

Blood, WBCs, glucose, and proteins

Characteristsic of urine

pH can range from 4.5-8.2 but average is 6.0. Output is around 1-2 liters per day.

Hematuria

Abnormal presence of blood in urine

Polyuria

Excess output of urine

Oliguria

Low output of urine

Fluid gains

Driven by thirst.

But also metabolic water, food, and drink

Fluid losses

Primary through urine.

But also feces, expires air, subcutaneous transpiration, and urine.

How many ureters does a person have?

2

What is the area of a kidney where the blood vessels enter/exit and the ureter exits?

hilum

Which part of urine formation happens in the glomerulus?

filtration

Which tube carries urine from the bladder out of the body?

urethra