Urinary system

Main functions of urinary system:

• Eliminate nitrogenous waste (proteins + nucleic acids)

• regulate blood volume + pressure

• regulate pH

• Regulate osmolarity

• electrolytes

• Produce RBCs

What stimulates urination

stretch of urinary bladder — medulla oblongata — micturition

Maintaining homeostasis in the urinary system

medulla oblongata + hypothalamus

Renal corpuscle

initial filtering process of the nephron

Glomerulus

in the renal corpuscle, filters blood

chronic hypertension can cause blood to not be filtered

Bowman’s capsule

forms renal corpuscle, surrounds glomerulus

• filtrates

Proximal convoluted tubules (PCT)

tubular fluid, reabsorbs H2O, amino acids, glucose, vitamin B + C

Nephron loop

• tubular fluid

• reabsorb H2O

Distal convoluted tubule (DCT)

hormone regulated

ADH

• produced to regulate water balance

• aquaporins: reabsorb H2O

Angiotensin II

reabsorb sodium, H2O follows (osmosis)

Glomerular filtration:

Passive- H2O + small solutes

Tubular reabsorption

glucose, amino acids, H2O, Na+/K+ balance

Tubular secretion (selective)

waste to urine

Angiotensin:

• reabsorbs Na+ and H2O (osmosis)

• hormone

Atrial natriuretic peptide

• secreted by heart

• secretes H2O

Antidiuretic hormone

reabsorbs H2O (aquaporins)

Role of sodium ions in reabsorbing water + other solutes

water always follows Na+ (osmosis)

Urinalysis

substances found in urine, abnormal substances + diseases or infection

Renal clearance

rate substances are removed

older = less sufficient kidneys

Creatinine

used to determine renal clearance

Normal components of urine

nitrates, creatine, pH = 4.5-8 (diet)

Abnormal things to find in urine

cells (RBCs, WBCs), proteins, glucose

How can renal clearance be used to estimate glomerular filtration rate

H2O soluble vitamins B and C

High protein diet, keto diet (what happens to pH?)

lower pH (amino acids)

High veggie diet, alkaloids, basics

high pH

Ureter

transfers urine from kidneys to bladder

Urinary bladder

holds urine until we are ready to micturate

Detrusor muscle

smooth muscle, compress urinary bladder

Urethra

transfers urine from to toilet

Micturition

active urination

micturition reflex

medulla oblongata

Male urinary tract

18 - 22 cm, remove urine, s*men, copulatory organ

Female urinary tract

3-4 cm, removes urine

Why are UTIs more common in women

They have a shorter urethra and perineum

Nephrosis

• excessive protein leakage to urine, swelling around ankles and eyes, low blood protein

• can kink ureter/blood vessels

• caused by too fast of weight loss

Diabetes insipidus

lack of ADH, pee a lot

Diabetes mellitus

lack of production of insulin, glucose in urine, pee a lot

Diuretics

make you pee

• ex. caffeine, alcohol, prescription diuretics

• lower blood pressure by lowering volume

Alcohol blocks ADH

makes you pee a lot

Renal calculus (kidney stones)

pain and chronic dehydration

• treatment = lithotripsy sound waves to make stones kick loose

Dialysis

clean blood of waste

Polycystic kidney disease

• cysts on kidneys

• nephrons bloom in liquid filled cyst

• autosomal dominant

• may need kidney transplant

Hematuria

blood in urine

Ureteroscope

tube down urethra to break down kidney stones