Blood Flow Through the Kidneys

The kidneys are responsible for filtering waste products and excess water from the blood. Here’s the journey of blood within a kidney:

1. Aorta: The big highway of blood, the aorta, delivers oxygen-rich blood to the kidneys through the renal arteries.
2. Renal Arteries: These branch out into smaller arteries within the kidney, like smaller highways feeding into city streets.
3. Segmental Arteries: These arteries dive deeper into the kidney, reaching specific sections.
4. Interlobar Arteries: Imagine these as major roads within a neighborhood, supplying blood to a particular region of the kidney.
5. Arcuate Arteries: These are like curved bridges, arching over the border between the cortex (outer layer) and medulla (inner layer) of the kidney.
6. Interlobular Arteries: These act like smaller roads branching out within the cortex, delivering blood closer to the filtering units.
7. Afferent Arterioles: These are tiny arterioles, like narrow alleys, that lead blood directly to the glomerulus, the filtration unit of the kidney.
8. Glomerulus: This tiny ball of capillaries acts as a filter. Blood pressure pushes fluid and waste products from the blood into a capsule surrounding the glomerulus, while blood cells and proteins stay behind in the blood circulation.
9. Efferent Arterioles: These are the exit points for filtered fluid, now called filtrate, leaving the glomerulus through narrower arterioles.
10. Peritubular Capillaries: These capillaries surround the tubules, the tiny tubes that reabsorb water and needed substances from the filtrate back into the bloodstream.
11. Vasa Recta: These are special capillaries that dip down into the medulla, allowing exchange of nutrients and waste between blood and the deeper regions of the kidney.
12. Renal Veins: The filtered fluid, now urine, exits the kidney through collecting ducts that merge into the renal pelvis. Cleaned blood from the peritubular capillaries and vasa recta flows back together and exits the kidney through the renal veins, eventually returning to the heart.

Urinary Tract Structures

Urine travels a specific path after leaving the kidneys:

1. Ureters: These are two thin, muscular tubes that carry urine away from the kidneys. They propel urine downward due to muscle contractions (peristalsis).
2. Urinary Bladder: This muscular sac acts as a reservoir for urine. As urine accumulates, the bladder stretches, triggering the urge to urinate. Muscles in the bladder wall contract during urination to expel urine.
3. Urethra: This is a tube that carries urine out of the body. In males, it’s longer and passes through the penis. In females, it’s shorter and located anterior to the vagina.

Causes of Acidosis

Acidosis is a condition where the body becomes too acidic due to an imbalance of acids and bases. There are two main types:

• Respiratory Acidosis: This occurs when the lungs can’t remove enough carbon dioxide (a major acid) from the blood. Examples include:

  • Chronic obstructive pulmonary disease (COPD)
  • Severe asthma
  • Drug overdose that depresses breathing
  • Sleep apnea

• Metabolic Acidosis: This happens when the body produces too much acid or can’t eliminate it effectively. Examples include:

  • Diabetic ketoacidosis (uncontrolled diabetes)
  • Lactic acidosis (intense exercise, lack of oxygen)
  • Kidney failure (kidneys can’t eliminate acid waste products)
  • Ingestion of toxins (like methanol)
  • Severe diarrhea (loss of bicarbonate, a base)