Anatomy and Physiology Lecture - Final exam 2024
Blood supply of the kidneys
Afferent arteriole --> glomerulus --> efferent arteriole --> peritubular capillaries and vasa
recta (associated with nephron loop)
Where does filtration occur in the nephron loop
afferent arterioles and the glomerulus
Where does reabsorption occur in the nephron loop
Proximal conv. tubule, nephron loop, distal conv. tubule, and collecting duct
Where does secretion occur in the nephron loop?
Proximal conv. tubule, distal conv. tubule, and collecting duct
What are the two types of nephrons?
cortical and juxtamedullary
What are the processes of the urinary system?
Filtration, reabsorption, secretion, and excretion
What is the formula for a secretion of a substance?
Filtered - reabsorbed + secreted = excreted
How much of the filtration is returned back to systemic circulation?
greater than 99%
What does the filtration membrane consist of?
Endothelium, Basement membrane, slits
Podocyte foot processes
Surround each capillary leaving slits through which filtration takes place. Extend around
glomerular capillary
mesangial cells
Help regulate glomerular filtration, phagocytic when needed, in the renal corpuscle
Net filtration pressure
the difference between net hydrostatic pressure and net osmotic pressure, starling
forces.
- Hydrostatic pressure (afferent arteriole) = 60mmHg
- Hydropressure in lumen = 18 mmHg
- Osmotic pressure (colloidal) proteins in plasma = 32 mmHg (resists filtration)
- Net Filtration pressure (60-32-18 = 10 mmHg)
Regulation of GFR
, GFR can be regulated by adjusting blood flow into and out of glomerulus and by altering
the glomerular capillary surface area available for filtration
- Intrinsic, Myogenic, and Autoregulation
- Insufficient urine production = low glomerular rate
- Excessive urine production = high glomerular rate
juxtaglomerular apparatus
in the nephron, the complex of cells from the distal tubule and the afferent arteriole
which helps regulate blood pressure by secreting renin in response to blood pressure
changes in the kidney; located near the glomerulus
tubuloglomerular feedback
mechanism by which glomerulus receives feedback on the status of the downstream
tubular fluid and adjusts filtration to regulate the composition of the fluid, stabilize its
own performance, and compensate for fluctuation in systemic blood pressure
- Intrinsic: Negative Feedback decreases GFR
Sympathetic Innervation on glomerular rate
- Decreases glomerular rate
- Result: Vasoconstriction of afferent arteriole decreases blood flow into glomerulus,
contraction of mesangial cells decreases filtration surface rate
- Net effect: GFR decreased and filtrate decreased; more fluid retained in blood, which
maintains blood volume
Maintaining glomerular filtration rate
- 180 L/day, 90-120 mL/min
- Controls:
-- Intrinsic (smooth muscles)
-- Juxtaglomerular cells
-- (macula densa --> paracrine --> smooth muscle contract0
-- Sympathetic input: NE, E: target are granulosa cells, JG apparatus, release renin
--> Renin, angiotensin, aldosterone RAAS. Pathway, target in this case are mesangial
cells where angiotensin causes contraction
Atrial natriuretic peptide (ANP)
hormone secreted from atrial cells of the heart in response to atrial stretching and an
increase in circulating blood volume. ANP has been identified as a diuretic that causes
sodium loss and inhibits the thirst mechanism.
- Antagonist Pathway
- Extrinsic, increases GFR
- Result: Vasodilation of the afferent arteriole increases blood flow into the glomerulus,
and relaxation of mesengial cells increases filtrate surface are
- Net Effect: GFR increased and filtrate increased; more fluid in the urine, which
decreases blood volume
- Stimuli: increase volume
Blood supply of the kidneys
Afferent arteriole --> glomerulus --> efferent arteriole --> peritubular capillaries and vasa
recta (associated with nephron loop)
Where does filtration occur in the nephron loop
afferent arterioles and the glomerulus
Where does reabsorption occur in the nephron loop
Proximal conv. tubule, nephron loop, distal conv. tubule, and collecting duct
Where does secretion occur in the nephron loop?
Proximal conv. tubule, distal conv. tubule, and collecting duct
What are the two types of nephrons?
cortical and juxtamedullary
What are the processes of the urinary system?
Filtration, reabsorption, secretion, and excretion
What is the formula for a secretion of a substance?
Filtered - reabsorbed + secreted = excreted
How much of the filtration is returned back to systemic circulation?
greater than 99%
What does the filtration membrane consist of?
Endothelium, Basement membrane, slits
Podocyte foot processes
Surround each capillary leaving slits through which filtration takes place. Extend around
glomerular capillary
mesangial cells
Help regulate glomerular filtration, phagocytic when needed, in the renal corpuscle
Net filtration pressure
the difference between net hydrostatic pressure and net osmotic pressure, starling
forces.
- Hydrostatic pressure (afferent arteriole) = 60mmHg
- Hydropressure in lumen = 18 mmHg
- Osmotic pressure (colloidal) proteins in plasma = 32 mmHg (resists filtration)
- Net Filtration pressure (60-32-18 = 10 mmHg)
Regulation of GFR
, GFR can be regulated by adjusting blood flow into and out of glomerulus and by altering
the glomerular capillary surface area available for filtration
- Intrinsic, Myogenic, and Autoregulation
- Insufficient urine production = low glomerular rate
- Excessive urine production = high glomerular rate
juxtaglomerular apparatus
in the nephron, the complex of cells from the distal tubule and the afferent arteriole
which helps regulate blood pressure by secreting renin in response to blood pressure
changes in the kidney; located near the glomerulus
tubuloglomerular feedback
mechanism by which glomerulus receives feedback on the status of the downstream
tubular fluid and adjusts filtration to regulate the composition of the fluid, stabilize its
own performance, and compensate for fluctuation in systemic blood pressure
- Intrinsic: Negative Feedback decreases GFR
Sympathetic Innervation on glomerular rate
- Decreases glomerular rate
- Result: Vasoconstriction of afferent arteriole decreases blood flow into glomerulus,
contraction of mesangial cells decreases filtration surface rate
- Net effect: GFR decreased and filtrate decreased; more fluid retained in blood, which
maintains blood volume
Maintaining glomerular filtration rate
- 180 L/day, 90-120 mL/min
- Controls:
-- Intrinsic (smooth muscles)
-- Juxtaglomerular cells
-- (macula densa --> paracrine --> smooth muscle contract0
-- Sympathetic input: NE, E: target are granulosa cells, JG apparatus, release renin
--> Renin, angiotensin, aldosterone RAAS. Pathway, target in this case are mesangial
cells where angiotensin causes contraction
Atrial natriuretic peptide (ANP)
hormone secreted from atrial cells of the heart in response to atrial stretching and an
increase in circulating blood volume. ANP has been identified as a diuretic that causes
sodium loss and inhibits the thirst mechanism.
- Antagonist Pathway
- Extrinsic, increases GFR
- Result: Vasodilation of the afferent arteriole increases blood flow into the glomerulus,
and relaxation of mesengial cells increases filtrate surface are
- Net Effect: GFR increased and filtrate increased; more fluid in the urine, which
decreases blood volume
- Stimuli: increase volume
