Kidney 2 Flashcards
This artery branches off the abdominal aorta
Renal artery
What does the renal artery do?
Brings unfiltered blood into the kidneys
Interlobar arteries: path
Travel down renal columns and between pyramids
Arcuate arteries: path
Arch over pyramids in cortical medullary junction
Interlobular arteries connect to
Afferent arteriole
Afferent arteriole branches off
Renal artery
Afferent arteriole controls
Blood flow into the glomerulus
Glomerular capillaries
- fist-like structure
- forms filter
Efferent arteriole
Carries blood minus filtrate out of glomerulus
Peritubular capillaries
- surround tubules and loop of Henle
- involved in reabsorption and secretion
Vasa recta
part of peritubular system responsible for concentrating urine and blood supply to kidneys
Renal vein delivers filtered and reabsorbed blood to
Inferior vena cava
Renal blood flow per minute
1000-1200 mL, or 20-25% cardiac output per minute
GFR =
Glomerular filtration rate
Rate of filtration and cleansing of blood
GFR is related to _____ and _____, and is controlled by these types of actions
- blood flow
- blood pressure
- neural/hormonal
Renal blood flow: auto-regulation
Arterial BP
80-100 mmHg
Renal blood flow: auto-regulation
These cells sense Na+ filtration
Macula densa
Renal blood flow: auto-regulation
What about this controls GFR?
Constriction or dilation of afferent arteriole
ANS regulation of RBF (renal blood flow)
Sympathetic
Sympathetic stimulation reflexively causes VASOCONSTRICTION of afferent arteriole
Reflexive vasoconstriction of renal arterioles: how does this affect GFR and RBF?
GFR and RBF are decreased
How does decreased RBF promote an increase in systemic pressure?
Decreased RBF
» decreased Na+ and water secretion
»» increased blood volume
»»» increased systemic pressure
This system is a large regulator of renal blood flow (And therefore, BP)
Renin-angiotensin-aldosterone system (RAAS)
Renin =
Enzyme formed and stored in cells of the juxtaglomerular apparatus
What causes renin to be released with the goal of increasing BP?
- Low BP sensed intrinsically by cells
- Sympathetic NS component (receptors located on cells)
- Macula densa cells sense low pressure in glomerulus (decreased Na+)
The effects of the RAAS combine with those of _____ to regulate blood volume
ADH
When is ADH release signaled?
- decreased BP or BV signals hypothalamus
- hypothalamus signals posterior pituitary to release ADH
What happens to water when ADH is released?
Reabsorbed into blood vessels from
- distal tubules
- collecting ducts
How does the RAAS impact BP?
RAAS RAISES BP!
Describe the RAAS
- Renin causes liver hepatocytes to release angiotensinogen
- ACE converts angiotensinogen to angiotensin I
- Angiotensin I » Angiotensin II
- Angiotensin II » Aldosterone
What else affects renal blood flow?
Effects of
- exercise
- hypoxia
- increased BP
Renal blood flow: effects of exercise
- sodium and water loss
- relative decrease in BV and loss of Na+ (sweating)
- increased BP
Renal blood flow: effects of hypoxia
- sympathetic response
- decrease in RBF
Renal blood flow: effects of increased BP
- renin and ADH decreased
- afferent arteriole dilated to increase filtration
The nephron filters blood/plasma to:
- reabsorb water, electrolytes, glucose, proteins within tubular system and capillaries
- maintain fluid volume, electrolyte balance, pH
GFR in a day
180L per day
GFR: how much urine produced per day?
1-2 L per day
How much water is reabsorbed by glomerular filtration?
99%
