Lesson 26: Urinary Anatomy

How is the Urinary system formed?

It is formed by

2 kidney

2 ureter

1 urinary bladder

1 urethra

How is urin formed and excreted?

After the kidneys filter the blood plasma, they return most of the water and solutes to the bloodstream.

The water and remaining solutes make up urine, which passes through the ureters and is stored in the urinary bladder until it is excreted through the urethra.

What are the functions of the urinary system?

• Regulation of water balance and acid-base balance.

• Excretion of metabolic residues and toxic substances.

• Regulation of blood pressure.

• Endocrine synthesis and secretion:

➢ Erythropoietin (endotelial cells of peritubular capillaries)

➢ Renin (pericytes of juxtaglomerular cells)

➢ Hydroxilation of Vit D3

External anatomy of kidneys

-Paired organs, reddish in color, shaped like abean

-right kidney is slightly lower than the left due to the space occupied by the liver

-concave medial edge faces vertebral column And contains renal hilum: contains ureter, blood vessels, lymphatic vessels, nerves

Where are the kidneys located?

Posterior to the peritoneum of the abdominal cavity = retroperitoneal

Located between T12 and L3 and partially protected by 11th and 12th ribs

What are the 3 layers of tissue (fascia and fat) that suround each kidney?

-Outer renal fascia

-adipose capsule

-innermost renal capsule

What are the 2 regions of the kidneys?

1. Renal cortex: Superficial area, light red

2. Renal medulla: a deep, reddish-brown area

How are the kidneys composed?

Composed of 8-10 conical renal pyramids

Bases are directed to renal cortex and its apex, the renal papilla, towards the hilum

What is the functional portion of the kidney and how are they composed?

Parenchyma = renal cortex and renal pyramids of medulla

What are the functional units of the kidney within in the parenchyma?

The nephrons

What is the path of urin drainage?

Collecting duct → Papillary duct → Minor calyx → Major calyx → Renal pelvis → Ureter → Urinary bladder

Filtration pathways anatomy and pathway

1. Collecting ducts collect filtrate formed in the nephrons

2. Empties filtrate into the minor and major calyces

Each kidney has 8-10 minor ans 2-3 major calyces

3. From major calyces, the urine drains into larger cavity calels renal pelvis

4. Then though ureter into bladder

5. Leaving body though urethra

What are the ureters and what is their function?

The ureters are 25-30 cm long and have diameter of 1-10mm

The ureter carries urine from Renal pelvis to the bladder.

Empty into the posterior wall of the bladder in an oblique direction

Where are ureters located?

Retroperitoneal

How is the urine propelled into the bladder?

By peristaltic contractions of muscular walls of ureters and by hydrostatic pressure and gravity

How is the reflux of urine controlled?

There is no valve that controls the reflux.

As the bladder fills with urine, the pressure inside compresses the oblique openings of the ureters and prevent reflux

What is the Urinary bladder and where is it located?

Hollow and dsitensible muscular organ

Located in the pelvic cavity, behind pubic symphsis

In men in front of rectum and in woman anterior to vagina and inferior to the uterus

How big is the capacity of the bladder

Between 700-800 mL

Smaller in woman because uterus occupies space above the bladder

What is inside of the bladder?

Triangular shaped area in the floor = Trigone

Two posterior angles of Trigone contain the two uteral orifices

Openings into urethra = internal urethral orifice located in the anterior angle

What is the Urethra?

Small tube which extends from internal urethral opening in the floor to the outside.

It is 4 cm long in woman and 20cm in men

The opening to outside is called external urethral orifice

What is the difference of secretion through urethra in Men and Woman?

In both men and woman it is the terminal portion of the urinary system.

In men it also releases semen

Where is the urethra and external urethral orifice located in women?

Women

Urethra = behind pubic symphysis

External urethral orifice = posterior to the clitoris and anterior to the external orifice of the vagina.

What does the male urethra pass through?

It first passes though the prostate, the deep muscles of the perineum and finally the penis

What are the 4 anatomical regions of the male urethra?

1. the pre-prostatic urethra, surrounded by the internal urethral sphincter. It prevents retrograde movementof semen into the bladder during ejaculation.

2) the prostatic urethra, which passes through the prostate,

3) the membranous (intermediate) urethra: it is the shortest portion and passes through the deep muscles of the perineum

4) the spongy urethra, the longest portion, which runs along the penis.

Which glands and other structures discharge their secretions into the male urethra?

1. the tubes that carry secretions from the prostate

2. the seminal vesicles and the vas deferens, which carry sperm to the urethra

3. the bulbourethral (Cowper's) glands that secrete an alkaline substance before ejaculation that neutralizes the acidity of the urethra

4. the urethral (Littré) glands that secrete mucus during sexual intercourse