Renal 2 Flashcards
skipped Renal Functions (8)
Regulation of water and electrolyte balance
Regulation of arterial pressure
Regulation of solute concentrations
(osmolarity).
Excretion of metabolic waste products and
foreign chemicals.
Erythropoiesis via Erythropoietin
Regulation of acid-base balance.
Regulation of active vitamin D (calcitriol)
production:
Gluconeogenesis.
Regulation of water and electrolyte balance
- Output = Input
Regulation of arterial pressure (2)
- Vascular resistance, Circulating volume
- Renin-angiotensin-aldosterone, AVP/ADH
Excretion of metabolic waste products and
foreign chemicals. (2)
- Urea, uric acid, creatinine, bilirubin…
- Drugs, pesticides, food additives…
Regulation of active vitamin D (calcitriol)
production: (2)
- Calcium homeostasis
- Dynamic bone structure
Kidney will increase or decrease
— rate of a substance to match
input
excretion
Ex. 10x increase Na+ intake leads to
compensatory increase Na+ excretion
Small period of time between (2)
disturbance and balance
Two kidneys –
Retroperitoneal
size of kidneys
fist
Two Major Regions of kidney
– Cortex
– Medulla
Medulla Composed of (2)
- Renal pyramids
- Renal Columns
Renal Pyramids (3)
- Contain Nephrons (Functional
Unit) – produce urine - Border of Cortex/Medulla
- Papilla
Urine dumped into (6)
Minor
Calyx Major Calyx Renal
Pelvis Ureter Urinary
Bladder Micturition Reflex
Ureter walls contain
smooth muscle
Ureters exhibit
peristalsis
Exhibit peristalsis (2)
- Calyces stretched by urine
- Initiates peristaltic wave that
flows through pelvis, along
ureter to bladder
Autonomic Nerves can alter
peristalsis (2)
- Parasympathetic enhances
peristalsis - Sympathetic decreases
peristalsis.
ureters enter Bladder through
Detruser Muscle (smooth muscle)
Enter Bladder through Detruser Muscle (smooth
muscle) (2)
- Muscle tone compresses ureter and prevents
black flow of urine during micturition - Peristaltic wave increase pressure within ureter,
opening ureter lumen, allowing urine to flow into
bladder.
Vesicoureteral Reflux (3)
- Backflow of urine into ureter
- Enlargement of ureters
- Increase pressure and damage to renal
pelvis
ureters and pain innervation
rich pain innervation
Ureterorenal reflex (3)
- Ureters blocked (ex. Ureteral stone)
- Reflex to reduce RBF and urine formation
- Protective
Visceral sensory neurons detect
degree of bladder stretch
Parasympathetic neurons stimulate (2)
contraction of detrusor
muscle and relaxation of Internal Sphincter
Pudendal nerve =
somatic motor neurons controlling External
Sphincter
Sympathetic neurons control
bladder blood vessels
Micturition Reflex – Spinal Reflex --- Reflex Stimulus = Reflex Receptor = Afferent = IC = Efferent = Effector = Effector Response: - Local = - Systemic = Feedback =
Stretch Reflex Stimulus = bladder stretch Reflex Receptor = Stretch receptors in bladder wall Afferent = Visceral Sensory IC = Spinal Cord (Spinal Reflex) Efferent = Parasympathetic Effector = Detrusor Smooth Muscle Effector Response: - Local = Contraction - Systemic = Stretch Feedback = Positive
Smooth muscle relaxes to keep
— pressure relatively constant
tonic
Micturition Reflex (cont.)
After time (sec. to min.) reflex (2), and
bladder –
fatigues and ceases
relaxes
If bladder not emptied, reflex
remains
inhibited (min to hours)
and then occurs again
Frequency and power of
contractions — as
bladder fills
increases
Once powerful enough, inhibits — to override
voluntary control; allows urine
to —
Pudenden nerve
flow
Voluntary urination – (3)
contract abdominal muscles, increases bladder pressure, activates micturition reflex with voluntary relaxation of external urethral sphincter.
Blood Flow to Kidney
Very high blood flow (20% of
cardiac output).
Blood Flow to Kidney
Renal Artery branches off
—
Aorta
Blood Flow to Kidney
Enters kidney at —
hilum
Blood Flow to Kidney
Branches into
smaller and
smaller vessels
Blood Flow to Kidney
Unique —
microcirculation
Blood Flow to Kidney
sequence (3)
Venules Renal Vein Vena
Cava
Glomerular: (2)
High pressure for Filtration Afferent and Efferent arteriolar resistance can be altered to alter PC in Glomerular Capillaries
Peritubular: (2)
Low pressure
Secretion and reabsorption
Renal Microcirculation:
Two Arterioles, Two Capillary Beds
sequence (5)
Afferent Arteriole Glomerular Capillaries Efferent Arteriole
Peritubular Capillaries Venules
Functional Unit of Kidney =
The Nephron:
Different Segments, Different Functions
Each Collecting duct Collects fluid from about — nephrons
4000
— Collecting Ducts/Kidney
250
≈ — Nephrons/Kidney
1,000,000
Two Classes of Nephrons
cortical
juxtamedullary
- Cortical (4)
70-80% of nephrons Glomerulus in outer cortex Short loops of Henle Peritubular Capillaries
- Juxtamedullary (5)
20-30% of nephrons Glomerulus near cortex/medulla border Long Loop of Henle (extends deep into medulla) Vasa Recta Play role in concentrating urine
- Filtration (F) (4)
Function of Glomerular Capillaries Occurs via bulk flow Glomerular Filtrate is identical to plasma except protein free Glomerular Filtration Rate (GFR) =
Glomerular Filtration Rate (GFR) =
Rate of filtrate production (vol./time)
- Reabsorption (R) (2)
Removes wanted substances from glomerular filtrate and puts it back into blood in peritubular capillaries Passive and Active transport processes across nephron epithelium
- Secretion (S) (2)
Removal of unwanted substances still in plasma and secrete it into glomerular filtrate in nephron Passive and Active transport processes across nephron epithelium
- Excretion (E) (2)
Removal of metabolic waste
Urine exits collecting duct into
minor calyx
Ex =
Fx – Rx + Sx
water (L/day)
filtration:
reabsorption:
excretion:
180
179
1-1.5
sodium (mmol/day)
filtration:
reabsorption:
excretion:
25,560
25,410
150 (<1%)
glucose (gm/day)
filtration:
reabsorption:
excretion:
180
180
0
creatine (gm/day)
filtration:
reabsorption:
excretion:
1.8
0
1.8
Why do we filter so much and then expend so much
energy to return greater than 99% back into the ECF?
