juxtaglomerular apparatus

  histology of urinary system 

                       regulation of GFR 

buffer systems:  
carbonic acid
amino acid
hemoglobin
​phosphate 

Chronic Kidney Disease

buffer systems

                      Some (kinda common sense) key points:
*chemoreceptors monitor the ECF for changes in plasma volume or 
          composition/osmotic concentration of ECF, not the ICF
*water travels via osmosis following the ion gradient (water follows salt)
*excess water/electrolytes must be released and insufficient water/electrolytes
          must be ingested to maintain homeostasis 

  primary metabolic wastes excreted are:
​             urea      uric acid   creatine

circulation

pH (acid/base) balance

Polycystic kidney disease (PKD) is a genetic disease. PKD causes cysts to grow inside the kidneys. These cysts make the kidneys much larger than they should be and damage the tissue that the kidneys are made of. PKD causes chronic kidney disease (CKD) , which can lead to kidney failure and end-stage renal disease (ESRD). PKD causes about 2 percent (2 out of every 100) of the cases of kidney failure in the United States each year.

There are two types of PKD: autosomal dominant PKD and autosomal recessive PKD. Autosomal dominant PKD causes cysts only in the kidneys. It is often called “adult PKD,” because people with this type of PKD might not notice any symptoms until they are between 30 and 50 years old. Autosomal recessive PKD causes cysts to grow in both the kidneys and the liver. Autosomal recessive PKD is often called infantile PKD because babies can show signs of the disease in their first few months of life.

Dialysis

                      aldosterone 

Kidney stones and oxalates:  
Oxalates are found in many foods. They bind to calcium during digestion in the stomach and intestines and leave the body in stool. Oxalate that is not bound to calcium travels as a waste product from the blood to the kidneys where it leaves the body in the urine. There are many different types of kidney stones, but 8 out of 10 stones are calcium oxalate stones. If there is too much oxalate and too little liquid in the urine, calcium oxalate fragments create crystals. As the crystals begin to increase in number, they stick to one another to form a larger crystal known as a kidney stone.

                      2. Hormonal Regulation

Triggered by:
a. low blood pressure/blood volume/decrease in GFR  
c. stimulation of granular cells by sympathetic system
d. imbalance in osmotic concentrations in distal tubule                 next to macula densa

Response:
a. Granular cells release Renin
b. Renin triggers Angiotensin I formation
c. Angiotensin I converted to Angiotensin II by                                 Angiotensin Converting Enzyme (ACE) in lungs
d. Angiotensin II then:
     constricts efferent arterioles
     increases aldosterone production by adrenal glands
         which increases Na+ retention/ blood volume
     stimulates brain's thirst center = increases fluid intake
     increases ADH production = increases blood volume 
     activates sympathetic system :
             constricts systemic veins
             increases cardiac output
​             further stimulates peripheral vasoconstriction

                                                   Electrolytes:
 concentration measured in Equivalents = amount of +/- ions that produces                                                                                         1 mole of electric charge
                                                                             1 Eq = 1000 milli eq (mEq)
 most common problem = imbalance in gain/loss of Na+
 imbalance of K+ less common but more dangerous
​ other electrolytes: Ca2+, Mg2+,PO4 3-, Cl- 

Urinary Tract Infections (UTIs) are pretty common infections that happen when bacteria (likely from the skin or rectum) enter the urethra and infect the urinary tract. The most common type is a bladder infection (cystitis). Kidney infection (pyelonephritis) is another type of UTI. They’re less common, but more serious than bladder infections.

   btw...notice the countercurrent

PKD

                                                   step 1: glomerular filtration
   filtrate is produced by the glomerulus when the hydrostatic pressure pushes                             water and solutes through the filtration membrane.

                                                                         step 4: elimination
     multiple nephrons dump collected wastes and water into the collecting ducts > 
 papillary duct > minor calyx > major calyx > renal pelvis > ureter > bladder for storage>
                                             then micturition (urination) via urethra 

transplanation

   anti-diuretic hormone = ADH

    Potassium

                                                     step 2: tubular reabsorption
the filtrate contains water and wastes like urea, but also glucose, amino acids, salts.   
​                        Selective reabsorption is necessary to reclaim these substances.  

                and when blood pressure is too high...
          enter Atrial Natriuretic Peptide/ ANP

Urinary System

pathologies

circulation

                                                     Homeostasis requires fluid/electrolyte/pH balance

      and the rest...

 steps in urine formation

                          1. Autoregulation
                        low blood pressure
        baroreceptors of granular cells triggered
           ​​macula densa releases adenosine
    vasoconstriction of afferent arteriole occurs
                          GFR decreases
                     water loss decreases
                   blood volume increases
                  blood pressure increases

                                                        Water
 average production via cellular respiration = 300 ml H2O/day
 average loss of water via excretion/perspiration = 2500 ml H2O/day
​    (one degree of fever increases H2O loss by 200 ml/day...
                           drink plenty of water when you are sick)
                                     Dehydration = too little
                               Hyperhydration  = too much
   Fluid shifts occur between ICF and ECF via osmosis to maintain                                                           homeostasis

     Sodium

                                                           step 3: tubular secretion
  substances including wastes are transferred from the peritubular capillaries to the                       tubular lumen. it's the opposite process of reabsorption. 

tubular secretion of K+ determined by:
K+ concentration in ECF
low pH...H+ is secreted instead of K+ in Na+ pump
amount of aldosterone released (affects NA+/K+ pump 

Urinary Tract Infections (UTI)

      Calcium