urinary system

Urinary system

Filtration of blood leading to secreting urine

Components of urinary system

• kidneys (2)

• Ureters (2)

• Urinary Bladder

• Urethra

Urinary tract

Composed of:

• Ureters (2)

• Urinary bladder

• Urethra

Local (specific) functions of urinary system

• Kidneys: filter the blood by removing waste products and convert filtrate into urine

• Ureters: transport urine from kidneys to urinary bladder

• Bladder: expandable muscular sac that stores as much as 1L of urine

• Urethra: eliminates urine from the body

Kidneys function

• filter blood by removing waste products

• Convert filtrate from blood into urine

Ureters function

Transport urine from kidneys to urinary bladder

Urinary bladder function

Expandable muscular sac that stores as much as 1L of urine

Urethra function

Eliminates urine from the body

Systemic (body) functions of the urinary system

• water volume regulation + solute concentration regulation

• Acid base balance: help ph in blood to be regulated by kidneys

• Excretion of metabolic wastes, toxins, drugs by kidneys

• Activation of vitamin D

Endocrine function:

• Renin: regulation of BP

• Erythropoietin: regulation of RBC production

Renin hormone

Regulates blood pressure

Erythropoietin hormone

Regulates Red Blood Cell production

Urinary system location

Retroperitonral (behind parietal peritoneum): in the back

Kidneys location

Left: between T12 and L3 vertebrae

Right: 2cm inferior to left kidney, between T12 and L3

Internal Anatomy of Kidneys

• renal cortex

• Renal medulla

• Renal pyramid

• Renal column

• Minor calyx

• Major calyx

• Renal pelvis

Renal cortex

Top part of internal kidney (around whole kidney)

Renal medulla

Middle part of renal pyramid

Renal pyramid

Pyramid shaped darker sections inside of kidneys

Renal column

The parts in between each renal pyramid

Minor calyx

Smallest funnel leading to bigger funnel which leads to biggest funnel

Major calyx

Big funnel leaded to biggest funnel

Renal pelvis

Biggest pyramid shaped funnel that leads to ureter

External kidney anatomy

• renal hilum

• Renal/Fibrous capsule

• Renal artery

• Renal vein

• Ureter

Renal hilum

Where all tubes come out of kidney together including the

• ureter

• Renal artery

• Renal vein

Renal/Fibrous Capsule

Protective layer surrounding kidneys

Renal vein

Carries filtered blood away from the kidney back to the heart through the IVC

Renal artery

Supplies kidneys with oxygenated blood from aorta

Ureter

Takes urine to bladder

Horseshoe kidney

Very large horseshoe shaped kidneys that make a person prone to kidney stones and UTI

Kidney transplant

Cut open groin, add 3rd kidney to iliac veins and arteries

Path for renal artery

(Blood to kidneys): Aorta → renal artery → afferent arteriole → glomerulus (capillaries)

Path for renal vein

(Blood leaving kidneys): Glomerulus (capillaries) → efferent arteriole → renal vein → IVC

Nephron

Smallest unit in kidneys that form urine (start in cortex and go down into medulla until entering minor calyx)

Two main parts of nephrons

• renal corpuscle

• Renal tubule

Renal corpuscle

Circle head at top of nephron

Contains:

• glomerulus which connects to efferent and afferent arterioles

• bowman’s capsule

Glomerulus

• Connects to efferent and afferent arterioles

• Filtration of blood occurs here

Bowman’s capsule

Surrounds glomerulus (Aka: glomerular capsule)

Where water, salts, glucose and wastes are pushed into from blood filtering

Renal Tubule

Wiggly part

• Proximal Convoluted tubule (PCT

• Nephron Loop (Henle’s Loop)

• - descending limb

• - ascending limb

• Distal Convoluted tubule (DCT)

Collecting Duct in regards to renal tubule

Follows renal tubule after DCT

Proximal Convoluted Tubule (PCT)

Proximal (close) to glomerulus

Reabsorbs

• 65-70% of water

• Sodium and other ions

• Nearly all glucose

• Amino acids

From the bowman’s capsule

Nephron Loop (Henle’s Loop)

Two parts

• descending limb

• Ascending limb

Descending limb of Henle’s Loop

• Water leaves and returns to blood (permeable to water) (osmosis)

• Salt stays

Happens due to osmosis of water, this limb has more water than surrounding kidney tissue which has more salt. Water goes to where there is less water which is the kidney tissue and leaves the limb. Vasa recta picks up water and takes it back into blood stream

Ascending limb of Henle’s Loop

• Salt leaves

• Water already gone (impermeable to water)

Thin part: salt diffuse out naturally (diffusion)

Thick part: kidney cells actively pump sodium and chloride out into surrounding tissue so water leaves in descending loop and salt can leave in ascending (active transport)

Distal Convoluted Tubule (DCT)

Distal (far) from glomerulus

• adjusts sodium levels

• Adjusts potassium levels

• Helps regulate blood pH

• Responds to hormones such as aldosterone

Collecting Duct

Last stop before urine leaves kidney

If body needs water: ADH (antidiuretic hormone) released causing more water reabsorbed by body instead of leaving with urine: darker and less urine

If body is well hydrated: less water is reabsorbed: lighter and more urine

Two types of nephrons

• cortical nephrons

• Juxtamedullary nephrons

Cortical nephrons

Nephrons in renal cortex only

Juxtamedullary nephrons

Nephrons close to medulla (dives all the way into medulla)

• most important for urine concentration as its saltiest toward the end of the pyramid