(05) Urinary System II: Urinary Tract

Question 1

(Functional Anatomy of the Kidney)

1. The kidney regulates the volume and composition of body fluids by what four processes?
2. Depending on the physiological need, water, molecules and ions are either conserved or eliminated

Answer 1

1. filtration, secretion, resportion, and excretion

Question 2

(Functional Anatomy of the Kidney)

(filtration)

1. What percentrage of the renal blood volume crosses the glomerular filtration barrier to the urinary (capsular) space?
2. The caliber of the afferent arteriole delivering blood to the glomerular capillaries is greater than or less than than that of the efferent arteriole draining them?
3. The results in what system?
4. Negative charges on the glomerular basal lamina repell what?
5. Molecules filtered out may be phagocytised by what?
6. Mesangial cells regulate flow through the glomerular capillaries by what properties?

Answer 2

1. 20%
2. greater
3. high pressure system to move blood fluids and solutes into the urinary space
4. anions and negatively charged molecules
5. mesangial cells or podocytes
6. their contractile properities

Question 3

(Functional Anatomy of the Kidney)

(Resporption)

1. How much of filtrate is resorbed in the proximal tubule?
2. Transit through the rest of the renal tubule adjusts the final composition of the filtrate according to what?
3. Regulation of kidney function is due to a number of what acting on what?

Answer 3

1. 2/3 to 3/4
2. physiological requirements
3. hormones acting on renal tubule epithelial cells (ADH and aldosterone)

Question 4

(Functional Anatomy of the Kidney)

(Transcellular pathway)

1. movement of substances thorugh the epithelial cells is active (requires energy) or passive?

(Paracellular Pathway)

2. movement of substances between cells depends on what and is active or passive?

Answer 4

1. can be either
2. leakiness of tight junctions; passive

Question 5

(Functional Anatomy of the Kidney)

1. active processes tend to occur where?
2. These cells have abundant what? and expanded what?
3. What type of processes tend to predominate in the less complex epithelia (eg the thin limb and the collecting tubules/ducts)?

Answer 5

1. the more complex epithelia (proximal and distal tubules)
2. mitochondria (energy); surface membrane (locations for transport proteins)
3. Passive processes

Question 6

(Anatomical Basis of the counter current multiplier mechanism)

1. What is the anatomical basis?

Answer 6

1. within the medulla bundles of descending and ascending tubules and collecting ducts are in proximity to bundles of descedning and ascending vasa recta.

This is the anatomical basis for the counter current that efficiently transfers ions and water from tubule to capillary and back

Question 7

1. JG apparatus releases renin from JG cells to initiate events leading to what?
2. Renin release is stimulated by several means - name one

Answer 7

1. vasoconstriction
2. one mechanism involves the macula densa and the extraglomerular mesangial cells which communicate with the JG cells via gap junctions

(Other hormones)

erythropoeitin - cortical intestinal cells

prostaglandins - intersititial cells, mesangial cells, podocytes