Overview of Urine Formation- Exam 2 Flashcards
What are some of the function of the kidney? (major functions)
Control volume and concentration of body fluids
Maintains environment cells need for proper function
Rid body of waste materials produced by body or ingested
filters the plasma
resorb much of the filtrate (return to blood)
secrete some substances (remove from blood)
substances that are secreted or not reabsorbed are excreted in the urine
What are some of the more specific functions of the kidney?
Excretion of metabolic waste products and foreign chemicals
Regulation of water and electrolyte balances
Regulation of body fluid osmolality and electrolyte concentrations
regulation of blood pressure
regulation of acid-base balance
secretion, metabolism, and excretion of hormones
gluconeogenesis
What does urea reflect??
Amino acid metabolism
What does creatinine reflect?
from muscle creatine
What is creatine used for?
create phosphocreatine which serves as energy source for production of ATP in muscle.
What day, what percent of creatine is converted to creatinine?
1 to 2 %
What is uric acid from?
nucleic acids
What is the end product of hgb breakdown?
Bilirubin
What does fluid/salt intake usually depend on?
Individual eating/drinking habits
What responds to changes in intake?
Kidneys
How does acid-base regulation occur in the body?
Kidneys work with lungs and body-buffer systems
What do lungs do to contribute to acid base regulation?
Remove carbon dioxide
What doe kidneys do to contribute to acid base regulation?
Control hydrogen ion and bicarb concentration
kidneys only way to remove sulfuric and phosphoric acid; byproducts of protein metabolism
How doe kidneys regulate erythrocyte production?
Secrete erythropoetin (almost all) which stimulates RBC production
What is the major stimulus for RBC production?
Hypoxia
What will have to patients will severe renal disease?
Develop anemia due to lack of erythropoetin production
What happens with glucose during prolonged fasting?
New glucose is produced from amino acids and other items
significant quantities can be produced
What percent of CO is renal blood flow?
22%
How many mls/min is renal blood flow?
1100 mls/min
What is the pressure in glomerular capillaries?
60mmHg; produces high rate of filtration
What is the pressure in peritubular capillaries?
13 mmHg; low pressure produces high rate of fluid reabsorption
What percent of nephrons are juxtamedullary nephrons?
20-30%
What kind of reflex is micturition reflex emptying the bladder?
Nervous reflex
What controls filling/emptying of the urinary bladder?
Autonomic spinal cord reflex
Input from cerebral cortex or brain stem
What is the smooth muscle of the bladder?
Detrusor muscle
What is the tone that holds urine in the bladder?
Internal sphincter; smooth muscle
What is the voluntary control by the nervous system; conscious prevention of urination?
Externer sphincter; skeletal muscle
What nerves are the primary supply to the bladder?
Pelvic nerves
What is responsible for initiation micturition reflex?
Sensory fibers from posterior urethra
What nerve controls the skeletal muscle fibers that provide voluntary control of external sphincter?
Pudendal nerve
How is sympathetic control accomplished in the bladder?
Hypogastric nerves; controls blood vessels
When are pain nerves in the ureters stimulated?
Blocked ureters response with intense reflex constriction which sends sympathetic stimulation back to kidneys to constrict renal arterioles (ureterorenal reflex)
What does the composition of urine not change?
once it leaves the collecting ducts
What acts as pacemaker for peristaltic contraction of smooth muscle?
Renal calyces
What do renal calyces do?
Force urin down into renal pelvis down the ureters into the bladder
What does increased stretch of calyces do?
Increases peristaltic rate
What are renal calyces innervated by?
Parasympathetic (enhances peristalsis) and sympathetic (inhibits peristalsis) nerves
What muscle prevents backflow from bladder to ureters?
Detrusor muscle; especially during bladder contraction
What increases pressure with ureter to open passage to bladder?
Peristaltic waves down ureter
What will occur if ureter is not long enough to pass through wall of the bladder?
Reflux will occur
