Renal Flashcards
What are the 6 main functions of the kidneys in the entire body?
- regulation of ECF volume and blood pressure
- regulation of osmolarity
- maintenance of ion balance
- homeostatic regulation of pH
- excretion of wastes
- production of hormones
What is the specific function of kidney parts? 4
- Filtration from blood into the lumen of the nephron
- reabsorption from the filtrate in the lumen of the tubule back into the blood
- secretion from blood into lumen of the body
- excretion from lumen to out of the body
What is capillary pressure verse hydrostatic pressure?
- capillary pressure causes filtration
- hydrostatic pressure is blood pressure
What is oncotic pressure?
- colloid osmotic pressure
The pressure from having things dissolved in the blood
How is fluid pressure created in the kidney?
By fluid in the Bowman’s capsule
How much plasma is filtered in the glomerulus?
Only 20%
Where does reabsorption occur in the kidney?
All tubules
Where does secretion occur in the kidney?
Proximal and distal convulated tubules, collecting duct
List the stages of filtration throughout the kidney
- Plasma volume entering afferent arterioles = 100%
- 20% volume filters in glomerulus
- > 19% of fluid is reabsorbed
- > 99% of plasma entering the kidney returns to systemic circulation
- > 1% is excreted
What is the amount excreted equal to?
Amount excreted = amount filtered - amount reabsorbed + amount secreted
What are the filtration barriers in the glomerulus?
Podocytes: foot-like processes which surround the capillary, leaving slits through which filtration takes place
What three structures form the three-layer filtration barrier in the glomerulus?
The glomerular capillary endothelium, basal lamina and Bowman’s capsule epithelium. Filtered substance pass through epithelial pores and filtration slits
How is net filtration calculated?
Hydrostatic pressure (blood pressure) (Ph) - colloid osmotic pressure gradient (pi) - fluid pressure (P fluid)
Describe factors of Glomerular Filtration Rate (GFR)
- rate is relatively constant (despite BP changes)
What are the two factors influenciing GFR?
- net filtration pressure: hydrostatic pressure - colloid osmotic pressure - fluid pressure
2. Filtration coefficient: SA of glomerular capillaries available for filtration; permeability of interface between the capillary ad Bowman’s capsule
How are the two ways GFR autoregulation?
- Myogenic response
2. Tubuloglomerular control
What is Myogenic response?
GFR regulation
- intrinsic ability of vascular smooth muscle to respond to pressure changes