Urinary System of Mammals and Avians

Urinary system

is responsible for filtering wastes from the blood and both forming and secreting urine.

Urinary System

These functions help to maintain the composition and volume of body fluids.

Kidneys

are round or bean shaped organs.

Kidneys

They are located outside of the peritoneum the membrane that encloses the organs of the abdominal cavity.

retroperitoneal

Because of this position of the kidneys, they are referred to as

Perirenal fat

Kidneys are surrounded by fat tissue known as

Perirenal fat

A fibrous capsule covers the kidney

Hilum

The indentation of the bean shape of the kidney is called the

hilum

is the site where the renal artery enters the kidney and both the renal vein and ureter exit.

• Outer cortex

• Inner medulla

Two Distinct Regions of Kidney

glomeruli

The cortex is where blood is actually filtered through small structures called

medulla

is where the urine is concentrated through a complex system of tubules.

Cortex and Medulla

They accomplish this by absorbing the water and electrolytes while preventing waste products from being reabsorbed.

nephron

One glomerulus and its corresponding set of tubules are called a

nephron

the microscopic functional unit of the kidney

nephrons

are the actual filtration elements of the kidneys.

Blood

enters the kidneys through the renal artery and travels through branching arteries.

afferent arterioles

These arteries coming into the nephron become smaller and smaller, and are finally called '_

high pressure

These arteries coming into the nephron become smaller and smaller, and are finally called 'afferent arterioles.' The blood in these vessels is under _

Bowman's capsule

The afferent arteriole branches into the glomerulus a cluster of capillaries within a shell called '_

pressure

The _ of the blood causes water, glucose, amino acids, and salts to leave the blood vessels and enter the Bowman's capsule.

glomerulus

The blood cells and most proteins are too big to be filtered out, and remain inside the blood vessel to be carried out of the _ via the efferent arteriole

tubules

Bowman's capsule leads to the network of _ that concentrate the filtrate into urine.

capillary

The tubules are surrounded by small blood vessel called a _

Capillary

is where materials are reabsorbed back into the blood.

proximal convoluted tubule

The first part of the tubule is aptly named the _ for its twisted shape.

proximal convoluted tubule

Here 99% of the water is reabsorbed along with all of the glucose and amino acids.

• glucose

• amino acids

The presence of _ or _ in the urine is a sign of disease

loop of Henle

The proximal convoluted tubule leads to the '_,' a long looping structure that extends down into the medulla of the kidney.

loop of Henle

More water and electrolytes (salts) are absorbed here.

distal convoluted tubule

Next, the filtrate is passed through the '_,' where excess potassium ions, hydrogen ions, and some drugs or toxins are passed from the blood into the filtrate.

collecting duct

This _ leads to the papillae of the pyramids, through the calyxes, and into the renal pelvis to be excreted through the ureter.

Ureters

are muscular tubes that transport urine from the kidneys to the urinary bladder.

Peristalsis

is a waving contraction of the muscles to propel the contents of a tube in one direction.

propelled to an opening

In this case, the urine is _ at the base of the bladder.

Urinary bladder

is a sac for the temporary storage of urine.

pelvic cavity

The urinary bladder is located in?

fibrous connective tissue

The outer surface of the urinary bladder is covered with

detrusor muscle

Inside the connective tissue of the urinary bladder is a muscular layer called the '_.'

detrusor muscle

This smooth muscle contracts to expel urine from the bladder.

submucosa

an elastic fibrous membrane that supports the mucosa, which lines the inside of the bladder.

transitional epithelium

The mucosa is composed of specialized cells called '_'

rugae

When the bladder is empty, the mucosa has many folds termed _.'

• rugae

• transitional epithelium

allow the bladder to stretch when filled with urine

urethra

The final passageway for urine out of the bladder is through the thin-walled

urethra

This tube runs from the base of the urinary bladder to the outside of the body.

females

In the _, the urethra is relatively short

males

In _, however, the urethra is longer.

• prostate gland

• external sphincter

The urethra in males passes through the _ (in those animals that have one) and travels the length of the penis before reaching the _.

• bladder

• urethral sphincter

The urethra in females connects the _ to external _.

domestic fowl

Like almost all birds, the _ does not have a bladder as is found in most mammals and amphibians.

No

Do domestic fowls have a bladder?

• ureters

• cloaca

• reverse peristalsis

• large intestine

The urine leaves the _ and enters the _ where it is moved by _ into the _, which permits excess water to be re-absorbed before elimination

kidneys of birds

are situated in the pelvic region of the body cavity; their posterior ends are usually joined.

kidneys of birds

They are lobulated structures with short ureters that open independently into the cloaca.

Yes

Do ostrich have urinary bladders?

semisolid uric acid

Urinary wastes, chiefly in the form of _, are eliminated through the cloaca along with feces