Exam 2 Flashcards
Renal and GI
Excretion rate of a substance
Excretion rate of substance:
Ux x UF
- concentration of substance in urine (Ux)
- Urinary flow rate
FIltration rate of a substance
Filtration Rate of a substance:
GFR x Px
-Px = plasma concentration of substance (x)
-GFR = rate of plasma filtered into Bowman’s space/time
Clearance is defined as the volume of plasma from which a substance has been completely removed and excreted into the urine per unit time (ml/min). What is the equation for clearance of a substance?
UF x Ux/Px
Urine flow = Urine Volume
The Clearance of Inulin is equal to the
GFR
GFR = UF x Uin/Pin
Clearance of PAH is equal to
RPF
RPF = UF x U(PAH)/P(PAH)
FIltration Fraction:
Fraction of plasma that goes to the kidney to get filtered
GFR/RPF
Components of Graph – PAH at top, Glucose at bottom
PAH:
- -100% cleared/excreted (filtered and secreted; not reabsorbed
- –highest clerance of all substances
- -filtered and secreted
- Inulin:
- freely filtered
- not reabsorbed; not secreted
- equal to GFR
- glomerular marker
- Chloride
- HCO3-
- Amino acids
Glucose:
–100% re-absorbed; no excretion (except in the case of diabetes)
= 0
–completely reabsorbed into the bloodstreatm
ADH/Vasopressin is secreted in response to
- high plasma osmolarity (high solutes in plasma) and decreased blood volume
- released from posterior pituitary
- Stimulates Na+ reabsorption in the TAL, DT and CCD & water reabsorption in the DT and CCD
When ADH is secreted: Water is _____ and urine is ______
When ADH is low, water is _____ and urine is _____
When ADH is released: Water is reabsorbed; urine is concentrated (less water)
When ADH is low: Water is cleared/excreted so urine is diluted with water
Aldosterone is secreted in response to
- secreted in response to low blood volume (via angiotensin II) OR increased plasma K+
- causes increased Na+ reabsorption
- Increases K+ secretion
Free water clearance:
UF x 1 - (Uosm/Posm)
Urine osm < Posm = positive clearance
Urine osm > Posm = negative clearance
- *High water in body = increase clearance = positive
- *Low water in body = decreased clearance = negative
Diabetes insipidus: Two types
Due to lack of ADH meaning you can’t concentrate urine
A. Central: doesn’t produce ADH or can’t release
–synthetic ADH increase plasma
B. Nephrogenic: ADH doesn’t bind B2 receptor
Polydipsia:
- -ingest too much water
- –lack of water will induce ADH and cause conc. urine
What is the normal physiological range for plasma osmolarity?
A. 50 – 100 mOsm/L B. 280 – 290 mOsm/L C. 0 – 50 mOsm/L D. 600 – 1200 mOsm/L E. 1200 – 5000 mOsm/L
Answer: 280-290
What is the normal physiological range for GFR?
A. 90 – 120 ml/min B. 0 – 50 ml/min C. 150 – 200 ml/min D. 200 – 250 ml/min E. 250 – 300 ml/min
90-120 ml/min
What is the normal fractional reabsorption of fluid in the proximal tubule?
A. Zero or 0% B. 0.5 or 50% C. 0.8 or 80% D. 0.67 or 67% E. 1.0 or 100%
67%
What is a normal physiological fractional excretion for sodium? A. Zero or 0% B. 0.5 or 50% C. 0.01 or 1% D. 0.8 or 80% E. 100%
0.01 or 1%
The clearance of which substance below best estimates GFR?
Sodium Potassium PAH Creatinine Urea
Creatinine
What are the two major stimuli for ADH secretion from the pituitary?
A. High plasma osmolarity and high plasma [Ca2+]
B. Low plasma [Na+] and high ECV volume
C. High plasma osmolarity and low ECV volume
D. High ECV volume and low plasma [K+]
High plasma osmolarity and low ECV volume
Fractional Excretion
amount excreted/amount filtered
fraction of filtered amount that gets excreted
Excretion/Filtration
Ux x UFR
GFR x Px
FE < 1
FE > 1 = net secretion
Know how afferent and efferent arteriolar resistance affects GFR and RBF
Changes in relative arterial resistance affect PGC, GFR and RBF
- -Constrict Afferent blood flow (slow the blood coming in) – no effect on efferent flow
- Decrease PGC, Decrease GFR, Decrease RBF
- -Decrease Efferent blood flow (slowed blood going out)–afferent blood flow gets backed up
- Increase GC, Increase GFR, Dec. RBF
Body Fluid Composition
TBW: 60%
ICF: 40% (2/3)
ECF: 20% (1/3)
ISF: 15%
PV (5%)Steps in Digestion
6 step process:
Ingestion
Propulsion
Peristalsis – alternate waves of muscular contraction and relaxation in the primary digestive organs. The end result is to squeeze food from one part of the system to the next
Mechanical Digestion
- physical preparation of food for digestion.
- Segmentation – mixing of food in the intestines with digestive juices.
Chemical Digestion
- Carbohydrates, Fat, and Proteins are broken down by enzymes.
Absorption
- transfer of the digested portion of food into the blood from the digestive canal.
Defecation
- removal/elimination of the waste products from the body.
Innervation to the gut
Regulated by autonomic nervous system
A) Parasympathetic nerves (Vagus and Pelvic nerves) and
B) Sympathetic NS (celiac, superior mesenteric, inferior mesenteric and hypogastric nerves)
C) Enteric division (Enteric NS) – Intrinsic
Myenteric plexus / plexus of Auerbach
Submucosal plexus / plexus of Meissner
1) Able to function independently from rest of nervous system
2) Linked to CNS by extrinsic sympathetic and parasympathetic nerves
Sympathetic nerves decrease GI secretions & motility
Parasympathetic nerves (Vagus and Pelvic nerves) increase GI
Lingual lipase
- mouth
- digestion of fat/lipids (triglycerides)
