12 topics with brief reviews: definitions, key facts, and seminar questions.
In this section, we analyze the physiology of excretion, a crucial mechanism for maintaining homeostasis. The main "protagonist" here is the kidney, or more specifically, its structural and functional unit — the nephron.
You will study all stages of urine formation processes: from glomerular filtration to tubular reabsorption. We will analyze in detail the function of the loop of Henle, distal convoluted tubules, and collecting ducts, the neurohumoral regulation of these processes, as well as renal functions, micturition, and urine composition. In addition, we will briefly touch upon extrarenal excretion mechanisms (skin, lungs, GI tract).
In seminars and exams, professors most frequently ask about the countercurrent multiplier mechanism of the loop of Henle, the mechanisms of action of ADH and aldosterone, and the factors determining the glomerular filtration rate. Pay special attention to these topics — they are classic "stumbling blocks" in normal physiology tests.
It includes protein metabolism products: urea (about 70%), creatinine, creatine, uric acid, amino acids, ammonia, and indican. Normally, its level is 200–400 mg/L.
Is sodium absorbed in the descending limb of the loop of Henle?
No, sodium reabsorption does not occur in this segment. The walls of the descending limb are formed by squamous epithelium, which lacks mitochondria and specialized enzyme systems for active ion transport.
Why does urine formation occur in multiple stages?
Metabolic waste products are present in the blood in very low concentrations. They cannot be filtered and eliminated all at once, so a sequential "conveyor" process is required.
What is effective filtration pressure?
This is the resultant force ensuring plasma filtration. It is calculated as the difference between the hydrostatic pressure of blood (pushing fluid out) and the sum of the plasma oncotic pressure and primary urine pressure (retaining fluid).
In which part of the nephron is glucose reabsorbed?
Normally, glucose is completely reabsorbed in the proximal convoluted tubules.
Master the entire topic in the "Physiology" course
This is a summary. The course covers everything tested in classes and exams.
4,128 pages of study guides covering all topics
Assignments and quizzes after every topic — just like in a colloquium