Module 3 Lecture - Urinary System Flashcards
What is the hilium?
An indent on the concave side of the kidney; the location where the renal vessels and renal pelvis enter and exit the kidneys
Functions of the urinary system
Excretion of waste through urine
Regulation of blood ion composition
Maintenance of blood osmolarity
Regulation of blood pH
Regulation of blood pressure (renin)
Hormone production
Regulation of blood glucose through gluconeogenesis
What hormones are secreted by the kidneys?
Renin - regulates blood pressure
Erythropoietin - red blood cell production
Calcitriol - helps calcium and phosphate absorption (Vitamin D)
Nephron
the functional unit of the urinary system consisting of a glomerulus and its tubules
- osmoregulation
- waste removal
Parts of a nephron
Renal corpuscle - tubular capsule wrapped around a glomerulus
- Glomerulus + glomerular capsule
Renal tubule - connects tubular capsule of rena corpuscle to urine-collecting ducts
- 3 segments - proximal convoluted, loop of Henle, distal convoluted tubule
Two types of nephrons
Cortical - 85% of nephrons; short loops of Henle
Juxtamedullary - 15% of nephrons; long loops of Henle
What do the glomerulus and glomerular capsule facilitate?
Blood filtration to create glomerular filtrate
Glomerular filtration
The process by which kidneys filter waste and excess fluid from the blood into urine-collecting tubules
Glomerular filtrate
The filtered-out fluid that enters the glomerular capsule
Filtration membrane
the barrier that separates the glomerulus and glomerular capsule and prevents large molecules from entering the capsule
3 layers of the filtration membrane
endothelium
basal lamina
visceral layer of podocyte cells
Key determinant of filtration rate through the filtration membrane
PRESSURE!
Glomerular blood hydrostatic pressure (GBHP)
PROMOTES filtration - pressure that forces liquid through the filtration membrane
Blood colloid osmotic pressure (BCOP)
OPPOSES filtration - the presence of large proteins prevents liquid from passing through the filtration membranes
Capsular hydrostatic pressure (CHP)
OPPOSES filtration - the presence of liquid in the capsule and renal tubule prevents liquid from passing through the filtration membrane
Tubular reabsorption
the process by which the kidneys remove water and solutes from filtrate and return them to the blood stream
- occurs in the proximal tubule of nephron
- reabsorbs water, ions, and larger molecules
- active and passive transport
Paracellular reabsorption
Transcellular reabsorption
Tubular secretion
the removal of harmful or unwanted substances (waste) from blood plasma
- ions (K, H, HCO3, NH4)
- creatinine and urea
- some hormones and drugs
What three processes determine urine volume and concentration and maintain homeostasis?
globerular filtration
tubular reabsorption
tubular secretion
