a. Around 7.4
a. enzymes stop working and normal physiological process breakdown
a. The body has buffering system
that requires both the kidney and the lungs working properly
a. Kidneys are paired structures that are located At the back of the peritoneal cavity
a. Kidneys are being supplied by the renal arteries which receive blood from the aorta
b. It takes about 25% of the cardiac output
a. Kidneys would have reduced blood flow and that leads to kidneys not working quite as well
a. 1500 L per/day
a. by reducing blood flow to other areas.
a. they will get pail clammy extremities because their peripheral resistance is increasing to keep as much blood pressure as possible in your central vessels in your aorta and renal arteries
b. therefore, the kidneys carry on being perfused with blood that contains oxygen, nutrients (skin, peripheral muscles can go for few hours without having too much blood)
a. Filter 1500 L of blood per/day
b. Fluid balance
c. Acid-base balance
d. Na balance
e. Excretion including active excretion of toxins and some drugs
f. involved in endocrine control of:
i. Ca and bones metabolism
ii. Hb (haemoglobin)
a. In glomerulus
a. Nephron
a. Blood from aorta comes to the renal artery in the kidney.
b. Renal artery divides into smaller arterioles until it gets to the smallest arterioles that feed the blood vessels in the glomerulus.
c. Glomerulus filters small molecules and water where the blood keeps bigger molecules (e.g. proteins)
d. Large molecules remain in blood, pass into vasa recta.
e. Whereas, high volume of fluid leaving the glomerulus, going to the proximal convoluted tubule.
f. Then the liquid passes through the proximal convoluted tubule into the descending limb of Henle. Then back up to the ascending limb of Henle
g. From the ascending loop of Henle, the urine then goes to the distal convoluted tubule and then to the collecting duct
- Limb of Henle: perform as a countercurrent multiplier and that is where the osmatic gradient is generated that allows the volume of water and the concentration of salt in the urine to be decided and adjusted.
a. Descending loop is permeable to water and as we’ve got very dilute liquid in this tube therefore, water diffuses passively out of that
b. Fluid in LoH becomes more hypertonic.
c. Ascending LoH, wall permeable to Na and Cl but not water and as we’ve got concentrated fluid coming up the loop, sodium, and chloride can diffuse passively out down the concentration gradient into the blood.
d. Fluid becomes more concentrated.
e. Water and salt reabsorbed into the blood
a. Generate the osmatic gradient that allow the other processes go on
a. Passive reabsorption
b. Passive secretion
c. Active secretion
d. Active reabsorption
a. The cells of the lining of the LoH are metabolically active and they will produce metabolites including ammonium
b. Ammonium is secreted from the cells passively down the concentration gradient
a. energy dependent process that actively pushes molecules either through the cell or out of the cell
Active secretion
* Drugs (penicillin)
* H+ and hydrogen ions
Active reabsorption
* Glucose
* Lactate
a. It occurs in the collecting duct
b. This process is controlled by Antidiuretic Hormone (ADH) which is secreted by the pituitary gland. In the pituitary gland the cells can sense blood pressure and blood osmolarity. The pituitary gland produces ADH when the blood pressure is Low and the osmolarity is high therefore, the ADH-dependent reabsorption in the collecting duct will stimulate reabsorption of water and that will lead to:
i. Increased water reabsorption
ii. Decreased urine output
iii. Increased blood volume which maintain the circulating blood volume
a. This is group of cells that is called Juxta-glomerular apparatus (JGA).
b. It is a point of contact of glomerulus and distal tubule/collecting duct.
c. The cells there can senses reduction in blood pressure, urine concentration.
d. If they sense drop in the Bp or increase in the urine concentration, then they will release Renin hormone
e. Renin catalyses conversion of angiotensinogen (from liver) to angiotensin 1
f. ACE catalyses conversion of angiotensin 1 to angiotensin 2. Leads to vasoconstriction increased BP
g. angiotensin 2 act on the adrenal gland and stimulates the secretion of the aldosterone increased water and Na retention.
h. Therefore, produce concentrated urine maintain BP