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108 Cards in this Set

  • Front
  • Back
What is the functional unit of the kidney
the nephron
The glomerulus has a glomerular capillary network and those capillaries are surrounded by
Bowman's Capsule
Where does filtration occur?
glomerulus
Where is the only capillary bed btw two arteries? control bp
glomerulus
What makes up 85 % of nephrons
cortical nephrons
What is 15% of nephrons?
Juxtamudullary
What are the functions of the kidney
homeostatic environment, endocrine fx, gluconeogenesis
What is homeostatic cellular environment
-balance water & solutes
-excrete metabolic waste
-conserve nutrients
-acid base regulation
Endocrine fx of the kidney
BP control, RBC production,
Ca+ balance VItamin D
What is renal clearance?
The volume of plasma completely cleared of a substance by the kidneys per unit time or the ratio of urinary excretion to plasma concentration
What is the formula for Renal Clearance
C=[U] * V/[P]
What is C
clearance
What is [U]
urine concentration of substance X
What is [P]
plasma concentration of substance X
WHat is V
urine flow rate per minute
Substances will have a high renal clearance when
they are both filtered and secreted
Inulin (a fructose polymer) renal clearance=
glomerular filtration rate....bc it is filtered but neither reabsorbed or secreted.
Inulin is considered
the glomerular marker
Clearance ratio is
the fractional clearance of substance X
Clearance ratio=
C(of x)/C(of inulin)
If clearance ration= 1.0 then
the clearance of x equals the clearance of inulin and also must be a glomerular marker
If clearance ration < 1.0 then
the clearance of x is LOWER than the clearance of inulin and either the substance is filtered and it is filtered and subsequently reabsorbed
If clearance ratio > 1.0 then
the clearance of x is higher than the clearance of inulin and the substance is filtered and secreted
The kidney takes what percentage of oxygenated blood?
25%
Renal flow is
inversely proportional to resistance
what does the SNS use to cause vasoconstriction in both types of arterioles?
catecholamines
What is the most potent vasocontrictor and the efferent arteriole is more sensitive to it?
Angiotension II
What causes the vasodilation of the renal arterioles?
prostaglandins
what in low doses also has a vasodilatory effect?
dopamine
renal blood flow remains constant over values of arerial pressure
80-200 mm Hg
Renal blood flow will decrease when MAP <
80
Myogenic hypothesis
is the stretching of vessels due to increased pressure. Stretching of vessels causes Ca++ influx which causes contraction in the smooth muscle of the blood vessel and therefore increased resistance
Tubuloglomerular feedback states that
when renal arterial pressure inc then both renal blood flow and glomerular filtration rate inc.
When GFR is inc the macula densa within the juxtaglomerular appartus senses this inc and scretes
a substance that causes vasoconstriction of the afferent arterioles and dec the flow
Hormonal regulation -
renin axis, ADH/AVP, ANP
Neurological regulation=
all sympathetic innervation no PNS
Norepinephrine is catecholamine involved via
baroreceptors, chemoreceptors and stretch receptors
Glomerular filtration is where
urine formation begins
Starling forces are responsible for
filtration across the glomerulus
Hydrostatic pressure of the capillary favors
filtration
Hydrostatic pressure in Bowman’s space
opposes filtration
oncotic pressure in glomerular capillaries
also oppose filtration
negative charge on the glomerular barrier which adds
an electrostatic component to filtration. If there is negative charge then obviously positively charged solutes will be attracted to it.
The net ultrafiltrate pressure
pressure is the driving force behind filtration and always favors filtration i.e. movement of fluid out of the capillary. The greater the net pressure, the higher the rate of glomerular filtration.
Creatinine Clearance
the clinical measurement of GFR (though it is slightly higher).
Blood urea nitrogen and serum creatinine concentration are both used to estimate GFR because
both are filtered across the capillaries. If BUN and Creatinine are not adequately filtered than their levels go up.
Tubular transport processes consist
of reabsorption, secretion and filtration. These three together = excretion (Figure 6-12).
Glucose reabsorption is an example
of a tubular transport process.
Glucose is filtered through the capillary and then reabsorbed by the
epithelial cells in the proximal tubule
Two step process:
Na+-glucose cotransport and facilitated glucose transport
Glucose has a transport maximum because
there is a limited number of glucose transporters
Urea reabsorption occurs passively
i.e. diffusion as opposed to glucose which is carrier mediated
PAH is an example of secretion. It is filtered across the capillary and secreted
secreted into the tubular fluid. Here PAH excretion is the sum of filtration + secretion.
Sodium Balance
is the most important function of the kidney
Positive Na+ balance =
ECF volume increase = edema.
Na+ is freely filtered
across the glomerular capillary
Potassium balance is essential for the normal fx of
excitable tissue
Water balance or body fluid osmolarity is maintained at
290 mOsm/Lby osmoregulation
Isosmotic urine=
blood osmolarity,
hyperosmotic urine=
higher than blood osmolarity
concentration of urine occurs via
ADH
ADH has three actions on the renal tubules
1. inc water permeability of the principal cells of the late distal tubule and collecting ducts
2. increases activity of K/Na/Cl transport system enhancing countercurrent multiplication and the corticopapillary osmotic gradient
3. ) increases urea permeability which enhances urea recycling and the size of the corticopapillary osmotic gradient.
Hyperosmotic Urine happens when circulating levels of ADH
are high (this is concentrated urine because the body is holding onto water so therefore urine will be concentrated as in SIADH or water deprivation).
Hyposmotic Urine happens when circulating levels of ADH
are low or when ADH is ineffective (this is dilute urine because the body is diuresising all of its fluid). Understand central DI v. nephrogenic DI.
conducting zone
brings air in and out of the lungs
respiratory zone
where gas exchange occurs
What i the main conducting airway?
trachea
Airways are lined with
smooth muscle that are innervated by both PNS and SNS
PNS=
constriction of airways via muscarinic receptors
SNS-
dilation of airways via B2 receptors on the bronchioles....
Why dont we give Beta blockers to asthmatics?
restrict airway dilation
Gas exchange occurs in
respiratory bronchioles, alveolar ducts and the alveolar sacs
HOw many alveoli in each lung
300
Alveolar walls are thin and have large surface area which allows for
quick and easy diffusion of oxygen and CO2.
Surfactant is produced by which type of alveolar cells?
2
Pulmonary blood flow =
cardiac output of the right heart
Bronchila circulation is the
blood supply to the conducting airways and does not participate in gas exchange
Tidal volume (TV)
the volume of air that fills the alveoli plus the volume of air that fills the airways (500 mL)
Inspiratory reserve volume (IRV)
additional volume that can be inspired about tidal volume (3000 mL)
expiratory reserve volume (ERV)
additional volume that can be expired below tidal volume (1200)
Residual volume (RV)
volume of gas remaining in the lungs after a maximal forced expiration...approx 1200
Inspiratoyr capacity (IC)
TV+IRV=3500mL
functional residual capacity
ERV+ RV=2400mL; volume of air in the ungs left over after a normal tidal volume is expired
vital capacity(VC_=
IC+ERV=4700mL; volume to be expired after maximal inspiration; this increases with body size, male gender, conditioning and decreases with age
Total lung capacity(TLC)
VC+RV=5900mL
Anatomic dead space
volume of the conducting airways=150 mL
Physiologic dead space
anatomic+functional amount of dead space of each alveoli
Minute ventilation=
VT*Breaths/min
Alveolar ventilation=
(VT-VD)*Breaths/min; VA alveolar ventilation, VT tidal volume, VD physiologic dead space
the alveolar ventilation equation is the
fundamental relationship of respiratory physiology
Alveolar ventilation=
alveolar PCO2
b. If CO2 production is constant than PACO2 is determined by
alveolar ventialtion
If alveolar ventialation increase then PaCO2
decreases
alveolar gas equation predicts
alveolar PO2 based on the alveolar PCO2
compliance=
distensibility
compliance of the lungs and chest wall is inversely correlated to
elastance
so the thicker the lung tissure the greater
the elastance and snap back and the less compliance
More negative pressure=
more inflation with air
The difference in the shape of the curves for compliance of inspiration and expiration is
due to the difference in surface tension of the lung during those times
Resting volume of the chest wall and lung system is the
functional residual capacity
Law of LaPlace
Large alveolus require little pressure to keep it open but small alveolus require a larger amount of pressure to keep it open.
a. Surfactant is a phospholipid that helps keep the alveolus
from collapsing on themselves.
Poiseuille’s Law
resistance increases then flow decreases. They are directly proportional to one and another.
a. Changes in diameter of the airways alters
resistance and airflow
a. Diffusion limited amount of gas transported is limited by the diffusion process
here the partial pressure gradient is maintained.
b. Perfusion limited amount of gas transported is limited by the blood flow or perfusion through the pulmonary capillaries.
Here the partial pressure gradient is not maintained.
c. The partial pressure gradient is the pressure across
the alveolus and capillary blood along the length of the capillary.
Brain stem control of breathing
medullary, apneustic, pneumotaxic